Children With Cerebral Palsy and Genetic Disorder Assignment

Children With Cerebral Palsy and Genetic Disorder - Assignment Example The present research has identified that the work â€Å"Quality of life of parents of children with cerebral palsy† is a cross-sectional design with a control group. It is not experimental in the sense that cerebral palsy is inflicted on the subjects. Instead, a post-test study is apparent, where the post-results of the effects of having cerebral palsy are examined. The authors wanted to know the differences and similarities in the quality of life conditions between parents with children who have cerebral palsy and parents who have healthy children. The authors chose the right research design because they aimed to know how cerebral palsy affects the parents, instead of children with cerebral palsy per se. The author has rightly presented that through the comparative approach, they can determine these differences and similarities and make deductions from the data. Sample Size: 40 parents of children with cerebral palsy aged 6-17 years.   The control group was composed of 40 p arents of healthy children (27 mothers and 13 fathers). Sample characteristics:   They are parents of children with cerebral palsy aged 6-17 years. These children were treated at the Department of Pediatric Rehabilitation of the Medical University of Bialystok.   Their cerebral palsy conditions are as follows: spastic tetraplegia - 18 (45%), spastic hemiplegia (hemiplegia spastica) -15 (37.5%), spastic diplegia (diplegia spastica) -7 (17.5%).

The Gulf Cooperation Council and the Impact of the Arab Spring Essay Example for Free

The Gulf Cooperation Council and the Impact of the Arab Spring Essay The Gulf Cooperation Council (GCC) is one type of trade bloc which called multilateral trade agreement where there is an agreement of multiple nations for coordination in specific fields. Also, GCC is known as the Cooperation Council for the Arab States of the Gulf (CCASG), and it was found in Abu Dhabi, United Arab Emirates on 25th of May, 1981 by joining 6 states allowing coordination and integration between the member states in all fields. The countries who served as member states are United Arab Emirates (UAE), The Kingdom of Bahrain, The Kingdom of Saudi Arabia, The Sultanate of Oman, Qatar and Kuwait. GCC mainly acts as a regional cooperation system among the Gulf Arab States in order to response to challenges derived from the surrounding circumstances. For the background, the GCC was established mainly in order to act as a defensive measure because they perceived the threat of Iran-Iraq war (1980-1988). In additional, the variables those helped in facilitating the establishment of GCC were firstly the geographical proximity among the GCC member states. Secondly, the GCC states have very similarity in term of their social conditions, regulations and economic structures. Moreover, in economic, they mostly depend on the oil exporting, and they are known as the organization that controls almost half of the worlds oil reserves. The GCC has the total amount of oil reserves about 480 billion barrels and Natural gas of 1,030 tcf (trillion cubic feet). Therefore, they are the worlds most important energy source. The Headquarter of GCC located in Riyadh, Saudi Arabia, and its official language is Arabic. The leader state of Supreme Council Presidency is United Arab Emirates and the Secretary General is Bahraini, Dr. Abdullatif Bin Rashid Al-Zayani. The total populations of member states are about 43. 5 million peoples. In additional, the total GDP of GCC was about US$ 940 billion in 2009, and the GDP per capita was about US$ 21,612. There are several basic objectives of the Gulf Cooperation Council. First of all, they aim to achieve unity among the member states by effecting in coordination, integration and inter-connection between them in all fields. Second, the GCC aims in both deepening and strengthening relationship between people of the GCC in order to create the links and areas of cooperation. The third objective is to formulate more similar regulations. The last objective is stimulating scientific and technological development in the fields of industry, mining, agriculture, water and animal resources. Moreover, they aim to conduct scientific research, also establishing joint ventures and encouraging the cooperation by the private sector. Moreover, they aimed to achieve cooperation with several countries and even other economic integrations such as EU and EFTA. Next is the discussion about the overall picture of the GCC’s strengths, weaknesses, opportunities and threats. For their strengths, they are the worlds largest oil exporter and having ample oil reserves, so they achieve high international bargaining powers, also they are in a strong position within the cartel because they are the main OPEC producer. Their second important strength is the boosted growth and improvement of the non-oil sector and infrastructure resulted from recent oil price boom. Moreover, their increasing number of population made a solid domestic demand for goods/services and infrastructure. And geographically, the member states are the well places for FDI in the region. For the weaknesses, the GCC is home to several violent Islamist groups and as they mostly depend on oil, so it means that their growth, exports and government revenue remain highly risk to the shifts in world oil prices. Moreover, their education system is not met the needs of the private sector and there are likely ongoing political obstacles. For the opportunities, the first one is there are more opening up to a wider range of political views of media. Second, there is slower growth and lower liquidity will bring inflation down domestically, cushioning the impact of the consumer slowdown. Third, the joining the WTO and pursuing a free trade agreement (FTA) with the US, China-GCC FTA, GCC Singapore FTA and GCC EFTA FTA mean liberalization will continue. For the threats, the GCC will be risk if there are any attacks on oil facilities which could lead to a disruption of output, which would be extremely harm to the overall economy because they given the reliance on this sector a lot. The second threat is some investors could be interrupted by perceptions about high security risk and high political risk which could result in increasing costs of insurance. There were several successes and failures of GCC. For their successes, it has been credited with successes that surprised even its members in a variety of issue-areas. Economically, the GCC is known as one of the most powerful organization among trade groups. For example politically, with the performance of the politically homogeneous GCC, is regularly mentioned as the most accomplished among the sub-regional institutions attempted in the Middle East. For example, the boundary demarcation crisis between Bahrain vs. Qatar (1982-1995), the GCC intervention at that time act as a primary cause of success in stop the crisis. For the failure, the GCC still failed to meet the pre-requirements to establish a monetary union in 2010 due to the GCC economies are oil dependent, have little intra-trade between members, lack convergence in macroeconomic fundamentals, and lack synchronization in business cycles. Arab Spring is a sequence of anti-government uprisings in various countries in North Africa and the Middle East, beginning in Tunisia in Dec. 2010. The main reason is to put an end to government oppression, corruption and incompetence. For the impact of the Arab Spring, there are the political changes, and then everywhere facing Arab Spring is in uncertain condition. The second impact is the need of finance support for reconstruction oil-importing countries, however the economies of the MENA oil-exporting countries, (including some GCC members-Bahrain, Kuwait, Oman, Qatar, Saudi Arabia,), are forecast to expand by 4. 9% in 2011, but those of the region’s oil importers are expected to grow by less than 2%. For the international response, the killing of civilians by Arab Spring governments drew strong protests by the United Nations and adverse reports by its agencies for example, Libyan civil war between the forces loyal to Muammar Gaddafis government and the anti-Gaddafi forces. Therefore, the biggest threat to business conditions in the GCC is the Political unrest in MENA, but the impact of â€Å"Arab Spring† is seen more positively than last May, both in the short term and the long term. In conclusion, the Gulf Cooperation Council even is in the competitive position in controlling the most important energy source in the world and has several international agreements which could create huge opportunities, but they are still facing several problems such as political problem, protesting, and impact from global economic crisis. Therefore, the carefully effective strategic plans and movements are still highly required.

Barbies Negative Impact on Society

Barbies Negative Impact on Society Cindy Jackson currently holds first place in the Guinness Book of World Records for undergoing the most consecutive cosmetic surgeries. While growing up, Cindy considered herself plain and unattractive next to her beautiful sister, so she decided that she had to do something. At age six Cindy was obsessed with looking like Barbie. Cindy stated, I looked at a Barbie doll and said, this is what I want to look like, I want to be her, (Leung 1). At age twenty-one Cindy packed up and moved to London, England, where she wanted to start a new, prettier life. It took over thirty-one surgeries, fourteen years, and five hundred thousand dollars to become the human Barbie. Now she has her own website, book, and multi-million dollar friends, at the expense of her body. Cindy Jackson is an example of how far people are willing to go to look perfect in this society. Beauty is distorted by the media and by the toy industry. In todays society skinnier is better, and people are willing to go through anything to achieve this. Children should not be exposed to these ideas. Instead, children should just be kids. Putting the Barbie doll into the hands of children teaches them that they need to look like her: perfect. Although, Barbie is not the only sole cause of low self satisfaction but is a contributing factor. Barbie has been proven to give children who play with her lower self-esteem and induce increased desires to look skinnier. Barbie has negative influences on body image and causes lower body satisfaction levels among young girls, by giving children false pretenses and pressures about being skinny and perfect. Barbie is the most successful toy of the twentieth century and the alleged icon of female beauty (Kuther 39). Most girls from the ages three to ten have at least had one doll growing up. Although, shes popular now she is actually based off of another popular doll from Germany. The dolls name was Bild Lilli she was an original cartoon character of an explicit comic strip designed for adult men. On August 12, 1955 Lilli was first sold in Germany, usually found in smoke shops and a few toy stores, (Bild 1). Barbie was based off of the Lilli doll by Ruth Handler; she journeyed to Europe on vacation and bought a few Lilli dolls. When she returned back to New York Handler re-designed the doll to make Barbie, which was named after her granddaughter Barbara. Now Barbie is the most sold doll in the world, Barbie is a 1.5 million dollar per-year industry (Dittmar 283). Barbie gives children a sense of low self-esteem. Three developmental psychologists exposed one hundred twenty-six English children from ages five to eight to a study of how Barbie influences body image. They were exposed to either Barbie dolls, Emme dolls (a more normal proportioned doll), or no dolls and then completed assignments based on what they saw. Helga Dittmar concludes, Girls exposed to Barbie reported lower body esteem and greater desire for a thinner body shape than girls in the other exposure conditions (284). Dittmar continues, even if dolls cease to function as aspiring role models for older girls, early exposure to dolls epitomizing an unrealistically thin body ideal may damage girls body image, which would contribute to an increased risk of disordered eating and weight cycling (290). This study proves the fact that Barbie has some kind of hold over kids. Since girls play with these dolls they are the most influenced by her since they are so young. If we show our chi ldren these images and tell them to play with them, they will show some sort of idolizing to the dolls. Handlers granddaughter Stacey has written a book about her complications with living in the shadows of the Barbie doll. She has had many challenges maintaining her weight to blend into the family. Stacey Handler has experienced the life after Barbie as it has been in her life personally. Her book The Body Burden, Living In the Shadow of Barbie reveals her personal story of a lifetime battle with body image. She openly discloses her own feelings about the Barbie doll, her grandmothers seemingly innocent perfect creation. She shares her moments of low self-esteem, including fears, insecurities, and distorted body image that have been bestowed on her (213). She discusses societys unrealistic body images and how hard it is for girls to adjust and love themselves for who they are (215). For the first few chapters she expresses her feelings through poems and rhyming songs (1). Handler writes, They never see behind the curtains that hide all my imperfections I was removed from the shelves where the perfect me remained without a single tear I worked all day and night to get rid of my excess cellulite until I looked perfect in the eyes of society (12-13). Stacey felt overwhelmed by what her grandmother had invented. She was constantly dieting and practicing unhealthy habits of losing the excess weight. Secondly, includes the controversial information of the Barbie. This includes the real life Barbie and her measurements. Barbie was designed to look flawless because why would a child play with a doll with blemishes or cracked dry skin. These dolls are made to look perfect and almost robotic (one looking exactly like the other). Even though Barbie has recently turned fifty years old she still looks like she is twenty. She stays so young only because children would not play with a grandmother looking doll, it would be out of their likely hood to play with her. The children would not look up to her. Her body figure is very controversial because it demonstrates a tiny waist, long legs, ample bosom, and flowing blond locks (Winterman 1). Some argue her body shape would be unobtainable and unsustainable if scaled up to life-size. Denise Winterman states, They claim she would not be able to stand up because her body frame would be so unbalanced. A real life Barbie would simply fall over .A study at Southern Australia University suggest the likelihood of a woman having Barbies body shape is one in one hundred thousand so not impossible, but extremely rare ( Winterman 1). Winterman claims, Researchers at Finlands University Central Hospital in Helsinki say if Barbie were life size she would lack the seventeen to twenty-two percent body fat required for a woman to menstruate. So again, not an unachievable figure, but certainly not a healthy one . If Barbie were a real person, she would stand five foot two inches and weigh approximately one hundred ten pounds. Her waist would measure a remarkable 20 inches, her chest thirty-eight inches, and her hips thirty-four inches (Kuther 322). Third toys give children an influence especially at younger ages. Barbie is indeed advertised to children who are young, mainly three to ten year olds. Children who play with toys at aged three to eight are said to be influenced more from the toys they play with than the ten year olds advertised too also (Duffy 1). Judith Duffy suggests that girls as young as five worry about their weight after playing with unrealistically slim figures such as the Barbie . Duffys article is a summarization of facts based on girls ideal of beauty within the past five years. For example, a recent study performed on one hundred thirty fifteen-year-old Scottish girls has revealed that around fifty two percent considered themselves to be too fat, and twenty-nine percent were actively trying to lose weight . This is outrageous considering that fifteen year olds are just beginning their high school career. These teenagers should be more concentrated on their studies than on their need to be perfect and size two. Some writers, feminists and psychologists think Barbie is a positive role model and a healthy image for young girls to have. For example, Deb Mehecke writer of the article Rethinking Barbie, explains that Barbie gives children a chance to use their imaginations and the opportunity to mother something . She also claims, Barbie allows young women to dream about all of the possibilities, Barbie can be a doctor, an astronaut, a banker, a lawyer, a nurse, a gymnast etc . Children do like to mother their toys and pretend they are real, but do we have to give our children such an inappropriate doll. We could give our children a water baby or a cabbage patch doll, why do we insist they take care of such a glamorous doll? Developmental psychologist Julia Griffin stated her idea of Barbie in her article Academics Like to Play with Barbie too. Griffin explains Barbie is essential to a girls development in a social interaction along with social values . Instead of Barbie being the essential part of a childs life, parents should help their children develop social interaction and social value skills. Many people think Barbie has nothing to do with eating disorders and the negative body image in young girls. Mattel, the company that produces the doll denies any and all negative accusations with Barbie and the negative affects it rings to the children who play with her. Solutions are a must with this issue such solutions are: alternate dolls for children and young teenagers, parent responsibility and positive reinforcement of body image, and companies need to make dolls more realistic. Some alternate dolls for young girls would be the Groovy Girl dolls, and the Cabbage Patch Kid dolls, and for the older age groups the American Girl Doll and Emme. The Groovy Girl dolls are sold at Target stores nationwide, and sell for about sixteen to nineteen dollars. These dolls can be considered expensive but they resemble children, in appropriate clothing and offer great values to children. The editor for the savvymom website and co-founder of the Groovy Girls is Victoria Pericon who appears on the official website she states, With three children of my own, I am constantly trying to filter the messages y kids are getting from television, their peers, the Internet, magazines, and movies. My daughter, especially, is surrounded by confusing messages that make it difficult for her to develop a strong sense and a healthy body image. The Groovy Girl dolls helped my daughter find her inner beauty in a respectful way, (Groovygirls.com). This website has a parents option which has ways to help your daughter learn to make good decisions along with characteristics parents should enforce. The Cabbage Patch Kid dolls are harder to find but they are so ld at Wal-Mart and Target stores along with other with other toy stores nationwide. They sell for about ten to fifteen dollars depending on the doll and accessories included. These dolls are positive for little children because they are realistic in their appearance according to the childs age group, and they can care for them properly. The American Girl dolls are by far the most educational and most expensive. These dolls are designed to teach children about a defined time period. For example, The Great Depression and the 70s dolls Kit and Julie. Although, these dolls are highly expensive and are more classy and high end of the doll market they include a lot of valuable information and insight into the girls influence. The final alternate doll would be the Emme doll. This doll is sold online and in select stores and is priced between twenty and thirty-five dollars. The optional extra outfits can cost anywhere from fifty to ninety dollars. These dolls are the most proportionate to an average healthy woman which makes this doll the best dolls for growing and changing children to teenagers. In conclusion, Barbie indeed became a staple of todays society based on her popularity but she is becoming a factor of low self-esteem in young girls. If we act now we can stop the increase in this matter before it gets even worse. References Anonymous. Bild Lilli History. 10, Apr. 2001.10, Nov 2009 . Dittmar, Helga, Emma Halliwell, and Susanne Ive. Does Barbie Make Girls Want to be thin? American Psychological Associationl.42.2 (2006):283-292. Academic Search Premier. EBSCO. Academic Search Premier. Web. 3 Oct 2009. Duffy, Judith. Barbies Figure gives Young Girls a Desire to have a Thinner Body. BNet.com.CBS. 12 Jun.2005.CBS, Web. 23 Sept. 2009. http://findarticles.com/p/articles/mi_qn4156/is_20050612/ai_n14680012/ Esteban, Michelle. Full-Figured Doll Transforms Beauty ImageABCNews.com. 25 Oct. 2002.Web. 2, Sept.2009.http://abcnews.go.com/US/Story?id=91099page=1 Groovygirls.com. 2008. 10, Nov. 2009 http://www.groovygirls.com/parents/raising.cfm. Handler, Stacey. The Body Burden, Living In the Shadow of Barbie. Cape Canaveral: Blue Note Publications, 2000. Print Kuther, Kara L. and Erin McDonald. Early Adolescents Experiences with and views of Barbie. Adolescence. 39.153. (Spring 2004): 39-51 Findarticles.com. Academic Search Premier.EBSCO. Web. 25 Sept. 2009. Leung, Rebecca. Becoming Barbie: Living Dolls. CBSNews.com. 6 Aug. 2004.Web. 24 Sept. 2009. http://www.cbsnews.com/stories/2004/07/29/48hours/main632909.shtml Winterman, Denise. What would a real life Barbie look like? BBCNews.com 06, March, 2009: 1-2. Web. 1 Oct 2009. http://news.bbc.co.uk/2/hi/uk_news/magazine/7920962.stm

Diabetes :: essays research papers

Diabetes is a life-long disease marked by elevated levels of sugar (glucose) in the blood. It can be caused by too little insulin (a chemical produced by the pancreas to regulate blood sugar), resistance to insulin, or both. Approximately 2.7 million or 11.4% of all African Americans aged 20 years or older have diabetes. However, one-third of them do not know it. The most life-threatening consequences of diabetes are heart disease and stroke, which strike people with diabetes more than twice as often as they do others. Adults with diabetes have heart disease death rates 2 to 4 times higher than those without diabetes. African Americans with diabetes are at increased risk for heart disease, stroke and other macro vascular complications. Other complications of diabetes include blindness, kidney disease, and amputations. Most African Americans (about 90 to 95 percent) with diabetes have type 2 diabetes. This type of diabetes usually develops in adults and is caused by the body's resistance to insulin and to impaired insulin secretion. Although it is a very serious disease, diabetes can be treated with diet, exercise, diabetes pills, and injected insulin. A small number of African Americans (about 5 percent to 10 percent) have type 1 diabetes, which usually develops before age 20 and is always treated with insulin. Insulin is a hormone that is needed to convert sugar, starches and other food into energy needed for daily life. The cause of diabetes continues to be a mystery, although both genetic and environmental factors such as obesity and lack of exercise appear to play roles. Major Types of Diabetes Type 1 diabetes results from the body’s failure to produce insulin, the hormone that â€Å"unlocks† the cells of the body, allowing glucose to enter and fuel them. This type of diabetes is usually diagnosed in children and young adults, and was previously known as juvenile diabetes. Type 2 diabetes is the most common form of diabetes. In type 2 diabetes, either the body does not produce enough insulin or the cells ignore the insulin. Sugar is the basic fuel for the cells in the body, and insulin takes the sugar from the blood into the cells. When glucose builds up in the blood instead of going into cells, it can cause two problems: †¢Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Right away, your cells may be starved for energy. †¢Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Over time, high blood glucose levels may hurt your eyes, kidneys, nerves or heart.

School Adjustment of Children from Divorced Families

The family is the basic unit of society where human beings are brought to life. It is considered a small society where children learn basic virtues. Therefore, the relationship between parents and children is very important for their growth and development. Through this relationship, children gain the virtues of trust, autonomy and initiative. Children also learn about socio-emotional relationships, self-respect and self-control. Thus, family environment and parent behaviour are crucial for children to grow as healthy, happy, and responsible people.Yet, despite the importance of parent support, there are still many children devoid of proper care from their parents resulting from the increasing number of divorces, or separations. In spite of the negative effects caused by divorce on children, the society seems to think divorce is something that can be easily done. Since the early 1990’s, divorce rate in Korea has risen rapidly not withstanding the fact that Korean society has a negative view on the divorce as compared to those in western countries. The influence of Confucianism is still deeply imbedded in Korean culture where family and marriage are supreme for most Koreans.Hence, many children from divorced families encounter deep-seated prejudice as if they have psychological defects. Although this may not be true for every child with divorced parents, some studies have shown that because they are exposed to a series of changes and are more disadvantaged than those who grow up in intact families, their school performance may be poor and they may exhibit antisocial behaviour. For example, children living in single parent families are less likely to have as many economic resources as children living in intact families.Other problems relating to aspects like parenting, education, housework, psychological issues will, as well, rise. Further, children of divorced families have to deal with sorrows from the absence of either their father or mother and that th ey will have to adapt to the change in family system. A study shows that children from divorced parents often become a laughingstock, and develop wrath towards their mother or father. Moreover, some children may find it difficult to focus during class, hence, receive poor academic grades. Childhood experience can have large impact in determining how they might turn out in the future.Parent-child relationship can largely influence children’s personality formation or intellectual development due to the account that children learn by imitating adults. Divorced parents may find more financial responsibility when it comes to parenting thus they may suffer from depression. Kurdek and Hetherrington also mention that single parent tend to raise their children with more rules and restrictions and less attention. Unfortunately, these single parents’ mental, emotional and family disorder difficulties will influence growing children and society at large. Parents’ divorce is a crisis which stirs up the ordinary life of children.For this reason, studies on divorce and its effects on children should be taken seriously. Divorce does not appear to have consistent effects across all children and ages as observed in two children, ages 10 and 11, from divorced families. Thus, this study is limited to elementary school age. It hopes to aid in understanding the behaviour of children from divorced families in school environment by illustrating researcher’s own experience with such children in class. It is related to theories which support their behaviour and possibly suggest ways for parents and educators to contribute to children’s well-being.The structure of this essay is as follows: ? the effects of divorce on children ? the differences between the children of intact and divorced families ? gender differences in the effects of divorce ? school adjustment of children from divorced families ? personal experience with children from divorced familie s The Effects of Divorce on Children Children’s reactions towards divorce can vary. Not only can the fact that the absence of one of the parents influences children but the change of environment after divorce settlement also affects children.They can suffer from psychological, behavioural and social problems. Psychological problems Study shows that children from divorced families have difficulties in adapting to new family environment. They are also likely to develop wrath towards one parent and some of them may even blame themselves for the divorce and show constant nervousness and incompetence. These effects may only be negative for a period of time or for children who have been exposed to parental conflict for a long time and recover rapidly in consequence of the stress released by their family environment.The most influenced psychological part of children of divorced families is that of depression and nervousness. Twenty-five percent of these children suffer from depressi on and fifty percent of them experience emotional turmoil or often appeared to be in despair. Social and behavioural problems Other influences on children from divorced families are external evidence like performance disorder, lack of sense of responsibility and understanding. They develop antisocial behaviour problems, aggressiveness, antagonizing manner and attention deficit in school settings.According to Lee’s research, during two years of their parents’ divorce children show antisocial behaviour and their social ability tend to decline. Children living with mothers exhibit impulsive behaviour, more oppositional and aggressiveness after two months of parents divorce. They also have difficulties in peer relationship and become troublesome at school, and perform lower academic achievement. Some children may seem to have overcome their parents divorce however even these children may have possibility of becoming troublesome when they are confronted with a new challenge and advancement task in school.As different studies have shown, divorce can have negative influence on children’s psychological, social and behavioural problems. Comparison between Children of Divorced and Intact Families Several researchers mention in their findings that children from divorced families differ significantly from children from intact families. Amato and Keith studied 13,000 children from preschool to young adulthood to find out if there are any significant behaviour differences between children of divorce and intact families.Their research indicates that children from divorced families have more problems in school, delinquency in the community, mental health problems and negative self-concepts. Besides differences in their behaviour problems, there is also a difference in economical stature. Children from divorced families are more likely to suffer from economic difficulty. Weitzman reported that woman’s standard of living after divorce falls by 29% th an previous household. And this can lead children to be more distressed in school from constant comparison with other children and receive lower academic achievement.This is because single parents may not have enough time to spend with their children because of their work and a decrease in income can increase frequent residential mobility. Hammaond compared the behaviour of children of divorced families and intact families and he found that boys of divorced families exhibit more behavioural problems than boys from intact families whereas girls show no significant differences. Boys from divorced families seem more distracted in class and exhibit acting out behaviour than boys from intact families do.This implies that in school setting, boys respond more negatively to their parent divorce than girls. The reason could be that in many countries including Korea, children live with their mothers after their parent divorce hence boys react more to absence of their father than girls do. Thi s means losing father’s monitoring homework or playing sports with them and sometimes there are issues they would want to share with their fathers only. From observing a student in class, I notice that sudden loss of affection from a father after divorce can influence school achievement.This is because children suffer from constant distress and tension and they become emotionally unstable. Therefore in comparison with children from intact families, their school grade naturally drops. However, recent studies show that nowadays there is less difference in the behaviour of children from divorced and intact families. This is probably due to the fact that divorce rate is increasing rapidly. Even though the difference is statistically significant, differences are becoming small.In Hetherington’s findings, she found differences between children of divorce and intact families, but she also found that children from intact families exhibit behavioural problems because of constan t parent conflict. She reports that over 90% of children including both genders from intact families are supposedly experiencing average range of problems. Remaining 10% suffer from severe family problem which would require professional help. In terms of children from divorced families, there are 74% of the boys and 66% of the girls in the normal range and remaining boys and girls are considered to have severe behavioural problems.Forty percent of adolescent boys and girls from divorced families have less behavioural problems than those from intact families. More recent studies show that the behaviour of children from divorced families are not much different from children of intact families. Based on experience, children still seem to experience considerable distress about the breakup of their parents and these feelings remain and affect them in some ways. Most of illustrated studies are carried in the West but Korea’s situation is also taken at hand to see if there are any b ehavioural differences in this area. Although H.Kim suggests that divorce is still viewed negatively in Korea, nevertheless her findings in the behaviour of children of divorce in school ages 8 to 13 shows similar effects of divorce on children’s school behaviour, which appear to be similar to that experienced by Western children studied in Amato & Keith’s research in 1991. Korean children from divorced families also exhibit aggressiveness, seek more attention and disobey in school. Gender Differences in the Effects of Divorce Besides behaviour differences among children of divorced and intact families, there are also gender differences to consider.Hyatt suggests that boys and girls react differently to parental divorce. Boys tend to create more behavioural problems in school than girls do. Boys’ self-esteem tends to decline as a result of divorce and they seek constant attention from the teacher and disturb class with irrelevant talks. Their effort in school wo rk also decline. Hyatt mentions that boys are more prone to difficulty of losing contact to their father hence regular communication with the father can help these adjustment problems.Girls’ behaviour in school after parental divorce is not as noticeable as boys because they do not manifest their difficulties by acting out in class. Rather, they tend to become more anxious or unhappy or showing over controlled good behaviour. Another findings concerning gender difference in the effects of divorce is that girls do accept help from their teachers unlike boys. This is because girls see their school as a place where they can be supported during divorce while boys conduct socially unacceptable behaviour.School Behaviour of Children of Divorced Families Human beings grow by constantly adapting to new environment therefore adapting to an environment is part of life cycle. Children’s educational place can be divided into home, school and the society. The child and environment continuously interact and the school takes over large part of a child’s life. Therefore as well as having a settled family life, school period is also important in determining how children might turn out in the future.School is a place where children enjoy, and gain sense of satisfaction by experiencing various activities and maintain harmonized relationships with the teachers and other students. Similarly, school adjustment is defines as taking interest in school environment and feel comfortable being in school with other children. This adjustment reflects on their school achievement and development. For instance, children who enjoy being in school and participate in school activities are likely to gain more educational experiences than those who have adjustment disorder.Liebman defines school adjustment disorder as excessive reaction where individuals are unable to harmonize with the school environment and other students which will prohibit individual development. Children of divorced families are likely to have more difficulties in school adjustment than those of children from intact families. Berbe suggests that children with adjustment disorder tend to attract teacher’s attention by inappropriate questions in class, distract other children and find it hard to pay attention in class. They also refuse teacher’s request and are often disobedient.And if they continue to show irresponsible academic behaviour, it leads to serious adjustment disorder. Heck’s idea is also similar to Berbe’s suggestion that children with adjustment disorder problems are frequently absent and tend to be oppositional in class. However, it is difficult to judge the cause of maladjustment solely on divorce. How children respond to above stress can vary from a child to child. It can differ according to their age, gender or disposition and the environment includes economic stature of parents, social approval rating of parents and family conflict.Variab les are categorized as they may affect children’s school adjustment into demographic differences and family variables. Demographic differences include race, gender, and parental socioeconomic status and family variables include relationships, organisation, control, social support, mother rejection and father rejection. Behaviour of children of divorced in school As mentioned earlier, children from divorced families appear to have difficulty in academic achievement and relationship with other children at school than children from intact families.The cause of this should not be looked at solely on the primary factor which is divorce. Secondary factors are to be considered as well, such as the change in socioeconomic structure and resources after divorce. For example, as mentioned earlier, economic loss, poor parental adjustment, lack of parental competence and parental loss can cause behavioural problems. As mentioned in the section of ‘Comparison between children of divo rce and intact families’, women’s standard of living is reduced by 29 % after divorce and absence of father can have negative influence on children more on boys than girls.Regarding studies on children’s maladjustment behaviour, Liner categorizes disorder behaviour as: ? action-out behaviour like hitting someone and being aggressive ? withdrawing behaviour: very quiet, sucking fingers, restricted behaviour ? defensive behaviour: lying, ignoring ? disorganised behaviour: escaping from reality Similarly, Wickman describes behaviour of children with adjustment disorder as: ? immoral, dishonest, in resistance to authority, stealer, cheater, disobedient, rude and rebellious ? often violates regulation of class, careless, loses interest in study, negligent and trustless? exaggerated and offensive personality ? unsociable, overly sensitive, and liar Based on experience, as a teacher of young children, those from divorced families have lower academic achievement, are so cially isolated, overly sensitive, either humiliate themselves or boast and show negative behaviour in class. Specifically, their academic grade is poorer than it used to be and they do not try to socialize with others in class. Further, they often seem absent-minded and tend to change their mood easily.If they are scolded for not doing their homework or asked to answer something they do not know, they use violent language in response. They also suffer from headache and easily get tired. This behaviour of children can also be explained by Rotter’s theory of locus of control. Locus of control refers to how individuals attribute the cause of their behaviour to internal or external forces. In applying to children of divorced families, children who have internal locus of control believe that if their parents are divorced, it is their fate.Therefore these children are able to handle any difficulties and feel less psychological distress. In contrast, children who have external locu s of control believe that if they do not perform well in school, they tend to blame external factors such as parental divorce rather than blame themselves. Hence, these children are likely to suffer from severe distress than those who have internal locus of control. When elementary school children experience parents’ divorce, they can become aggressive and develop sense fear and sorrow.Some children also imagine reunion of their parents. And they also explain that children’s school behaviour depend on how they are treated at home. As per experience, the relationship between custodial parent and the child seem to have a large impact. Prior research says that the relationship between the behaviour of custodial parents and children’s school adjustment illustrate that the attitude of custodial parents has large influence on children’s school achievement. Mothers’ affection can influence enormously on developing children’s social skills.From moth er-child relationship, children learn responsibility, self-control and social skills, hence, hostile attitude towards children can act as hindrance in developing social skills. Therefore one can learn that the attitude of custodial parent becomes important factor which influence children’s school adjustment. Personal Experience with Children from Divorced Families Case study 1 Two years ago, I was teaching young Korean children ages 8 to 11. Before I started teaching, I was briefly explained about the behaviour of several children by their tutors.A couple of them were from divorced families. I had a difficulty in handling one particular child called J, who was 11 years old at that time. According to his tutor, his parents were divorced recently and as a result, he enrolled in this school. I did not know the reason of his parents’ divorce but his mother was diagnosed with cancer. The tutor was the custodial parent of J. My first impression on J in class was that he was very loud and also it became a routine for him not to do his homework and turn up late in class.He became aggressive and tried to embarrass me by making ridiculous comments when scolded about his behaviour. On one occasion, J had a fight with another boy in class. J actually stabbed this boy with a pencil during break time. Although it was a minor injury, parents of both boys had to be called in and J’s tutor tried to make both boys talk about why it happened. But they did not say a word. Since J’s mother was sick, his grandmother came instead, apologizing for her grandson’s action. Nonetheless, explanation of J’s grandmother helped me to understand his behaviour.J became difficult to control since his parents’ divorce. He was furious with the fact that his father left his sick mother for another woman. His grade from previous school was average but with the change of family environment, he was achieving lower grade. However, considering he was fai rly new to the school, he seemed to socialize with other boys easily and seemed to lead them as well. I have also noticed that when he was not being loud or seeking attention in my class, he would sit absent-minded and continuously shake his leg. Besides being aggressive he was probably feeling insecure as well.In the period immediately following the divorce, J’s mother’s ability to be a good parent probably declined and became more inconsistent in disciplining her son due to her illness. J’s reaction towards his parent’s divorce is all mentioned in past studies by Anthony (1974), Hoyt et al. (1990), Kurdekrikberg (1987), Liner (1976), Wickman (1987) where action-out behaviour was most apparent in his behaviour when he had stabbed a boy with a pencil and his reaction also showed that he was very aggressive, as Lee (1993) suggested that children of divorce can become aggressive.J’s behaviour of making comments in class also shares Hyatt (1999)â€⠄¢s findings of making irrelevant comments in class. J had also developed anger towards his father because he had left his mother when she was sick and Kurdekriberg (1987) mentioned that some children may develop wrath towards one parent after divorce. As illustrated in Lee (1993), Kurdekriberg (1987) and Weitzman (1985)’s study, J’s academic grade declined and exhibited withdrawing behaviour (1976) such as shaking his leg in class.He was also spotted lost in thoughts in class sitting completely absent-minded and this can refer to what Liner (1976) called disorganized behaviour that J probably wanted to escape from this painful reality of his. Case study 2 Another child called B, age 10, in my class, also experienced parents divorce. I got to know B’s background through a homework I assigned in class. Unlike J, her parents were divorced when B had just turned 5 and at that time, none of her parents were willing to look after her. Therefore she was left under the care of her grandparents in her mother’s side for a few years.And then, she joined her mother at the age of 9 who was by then re-married and had children of their own. Being with her mother’s also meant moving to another school, hence everything was new to her. Despite the change of the environment, she seemed to have adjusted herself well in school life. She had her own circle of friends and she was also active and lively during class and there was not much change in her school grade. I also noticed her suck fingers during class. One day, I assigned the whole class to write about their parents because it was soon to be Parents’ Day in Korea.Surprisingly, B did not do her home. To be exact, she actually refused to do it because she said there was nothing to talk about and as she was saying this, she was almost in tears. Then she explained her family background and she was ashamed of it. She mentioned that her mother and stepfather hardly gave her any affection and treated her as a burden, hence in order to avoid them, B spent most of her time in her room when she was home. For B, the school was some kind of a safe zone and because of her positive attitude in class, I never thought that she was unhappy at home.In my opinion, B was putting all her energy into school life to forget about troubles at home. It was obvious that B had the most difficulty in adapting to step-parenting and remarriage and what made it worse was that she hardly knew her mother either. So confronting her mother and step father was a great distress for B. Unlike J, B’s behaviour was not very noticeable in school. It seems that in B’s case, her difficult situation acted as a driving force to concentrate in her school life.This is because she had hardly any affection from her mother that she probably had with her teachers and friends, whom she can trust and rely on as it is mentioned in Goldman, Rosenzweig & Lutter (1980) that girls from divorced families tend to see school as a supporting place. Both J and B suffered from painful memories and feelings of helplessness but how they reacted to the situation differed extremely although they both showed what Liner (1976) called sign of withdrawing behaviour: shaking leg and sucking fingers.There could be many factors which caused these differences. For example, J and B’s age difference, their gender and economic stature of their parents. Since J’s mother had an illness, they probably suffered severely from economic loss in comparison with B’s situation. And the fact that B’s parents were divorced years before J’s parents, could be another reason which caused adjustment difference in school. Last but not the least, attitude of custodial parent could be another reason.Although J’s behaviour problem seemed more serious than B’s, J probably had more attention from his mother where as in B’s case, she was not suffering from the fact that her parents were divorced but suffered from trying to adapt herself to step-parenting and remarriage. From J’s and B’s cases, it is evident that their behaviours were strongly influenced by family variables. Although J received much affection from his mother, he probably felt rejected from his father and B felt rejected from his mother. Although they were both influenced by family variables, J’s reaction was much more noticeable than B.Boys create more behavioural problems than girls, hence the influence of gender differences is also apparent in this study which is known as a demographic difference. It is clear that both J and B need support from educators. Although B is able to cope with this new challenge of living with a mother who she does not know well and adapting to step-parenting by herself, without professional help, it may trigger problems in her adolescence. It is the same for J’s case. If he does not receive appropriate help form educators, h e is likely to continue with delinquent behaviour or associate with antisocial friends in the future.Therefore it is vital that they are supported with affection so that they grow into a reasonably competent person. Conclusions This paper studies the behaviour of children from divorced families by studying the prospective relationship demonstrated and certain family experiences and school adjustment of two children I taught in Korea. Although past studies show that children from divorced families are in danger for developing negative behaviour and experience academic decline, due to increasing rate of divorce, the differences in the behaviour of children of divorced and children from intact families are getting smaller.It may be that children from divorced families are having difficulties, these are not as important as the factors that cause these differences. What I learn from these two children is that being a party to their parents’ divorce is a very difficult transition f or their age. There are many factors which may cause children’s school adjustment disorder and student J and B responded differently, owing to gender differences and new family situations. Therefore, children from divorced families, including J & B, should receive appropriate support both from parents and educators until they adjust to their new living arrangements.This will help them develop intellectually and socially in the same way as their peers from intact families do. Not only the support of parents is needed but teachers need to become more aware of children’s feelings in class. I, for one, am being considerate to children from divorced families in assigning homework such as writing letter to parents. Discussing different family situations, including single parenting and remarriage, will help children of intact families develop more awareness and respect towards children of divorced.Teachers can also spend more time with children from divorced families to under stand their feelings and perhaps suggest advice if necessary. This personal attention can help children to reduce any negative behaviour which children may exhibit as a result of parent divorce. In summary, on the basis of the findings of this study, it is suggested that educators should consider any factor that may influence children’s behaviour and conduct appropriate program in order to help them.

How did Great Britain, France, and the United States respond to the Great Depression? Essay

In Great Britain, there were economic difficulties. For example, the decline of several industries led to high unemployment. In 1929, the Labour Party, which was the largest party in Great Britain, couldn’t solve the problems and fell from power two years later. A new government brought Britain out of the worst stages of the depression by using budgets and tariffs. Britain wouldn’t go as far as deficit spending, though. France had become the most powerful power in Europe at the end of the war, and wanted to rebuild the parts of France that had been destroyed by the war. However, no French government was able to solve the financial problems at that time. Because France’s economy was more balanced, it felt the effects after the other countries did. However, when it did, there was political chaos. Eventually, Communists, Socialists, and Radicals formed a Popular Front government. The Popular Front made the French New Deal, based on FDR’s New Deal. It gave the right to do collective bargaining, 40 hour work weeks, two-week paid vacations, and minimum wages. However, France didn’t have much confidence in this system. In the United States, the industrial production fell to 50 percent of what it was in 1929. Franklin Delano Roosevelt, also known as FDR, pursued a policy called the New Deal. It created the National Recovery Administration, which required government, labor, and industrial leaders to work out regulations for each industry. However, it was declared unconstitutional by the Supreme Court, which said that the government shouldn’t intervene in the economy. The NRA was replaced with the Second New Deal and the Works Progress Administration. The WPA employed many people to build bridges, roads, post offices, and other buildings, so people could be paid and get the economy going again. The New Deal did not solve the unemployment problems of the Great Depression, though. Only World War II brought the United States workers back to full employment.

Educational Technology Essays

Educational Technology Essays Educational Technology Essay Educational Technology Essay Executive Summary Educational technology, also known variously as e-learning, instructional technology and learning technology is the use of technology to support the learning process. Though technology is used widely in the administration and management of education (i.e. student records, marketing, procurement, finance etc, for research purposes, educational technology is only concerned with technology as it impacts upon the learning process, such as delivering learning materials, facilitating communication and providing course assessment and feedback. Over the years, societyâ„ ¢s use of technology has become more frequent and complex. The demand for knowledge increases exponentially, with e-learning emerging as a major channel for meeting this demand. The key to a successful future educational technology is software and how it will be utilized. The future will be enhanced by software with PACE (presentability, accountability, customizability, and extensibility) characteristics. Introduction Research has shown that the era of pervasive technology has very significant implications for higher education. Nearly two-thirds (63%) of survey respondents from the public and private sectors say that technological innovation will have a major impact on teaching methodologies over the next five years (Consortium Glenn, 2008). Technology allows students to become much more engaged in constructing their own knowledge, and cognitive studies show that ability is key to learning success, says New York City-based Queens College vice-president of institutional advancement, Susan Henderson. Presentability is how the software appeals to the user. For e-learning students having three-dimensional graphics, enhanced stereo sound, and interactive devices that students can control and manipulate are all necessary elements of successful software. To enhance the appeal of the learning process, Software should also have varied presentation modes so it can be used the three ways people teach and learn: as a whole-class discussion to introduce ideas and concepts; with several users to support cooperative learning groups; and as individualized instruction, adapting to the needs and level of each user (this has been accomplished by online classrooms like WebTycho and Blackboard). Accountability is the second essential component of PACE. Evaluations of student work and course progress is what allows teachers to provide individual assistance and encouragement. This type of accountability was showcased with AMBA 640 for the three LREâ„ ¢s. Without some type of evaluation and objective accountability, educational software is useless. Customizability is the third essential element of sound educational software. Educational Technology should be malleable in the hands of the teacher so that it can be individualized to suite the needs for the different students. Extensibility is the final component of the PACE essentials for educational software. Software that is extensible is easy to augment, easy to take beyond its own environment, and supportive of the creation of new things. Recent surveys with business conclude that the most desirable traits in new employees are effective communication, ability to work with others, leadership, flexibility and maturity, resourcefulness, inquisitiveness, and the ability to learn. Software with the PACE characteristics supports the development of these very traits. Future of Educational Technology The future of educational technology is consists of, but not limited to: 2 Way Communication (We the Media via blog and podcast), Social Learning (Facebook + Ning + Wiki), Hands On Learning + Virtual Project Management, Mobile and iPhone (Handheld), Fundamental cultural and generational shift (Digital Natives), Real time distance learning (Skype + Oovoo and Wimba), Findability for academic content, and Entirely new communication + interaction + business models (Top Future Trends in Educational Technology and E-learning, 2009). Because online learning is gaining a firm foothold in universities around the world. More than two-thirds of respondents from academia say that their institutions offer online courses. Many of them, especially those with a public-service mandate, consider online learning key to advancing their mission, placing advanced education within reach of people who might otherwise not be able to access it (Consortium Glenn, 2008). There are three major reasons why e-learning will continue to grow in the future: (1) the economy has tanked. Most companies are trying to achieve cost savings using e-learning technologies (i.e. online training courses, Intranet modules). (2) Students make more of a conscious effort make better use of their money and time; they will find ways to take advantage of e-learning opportunities. (3) Green initiatives for corporations will also create a need for e-learning. Educational researchers have found that Technology has had†and will continue to have†a significant impact on higher education (Consortium Glenn, 2008). Nearly two-thirds (63%) of survey respondents from both the public and private sectors say that technological innovation will have a major influence on teaching methodologies over the next five years. In fact, technology will become a core differentiator in attracting students and corporate partners (Consortium Glenn, 2008). (2009, June 5). Retrieved September 10, 2010, from Top Future Trends in Educational Technology and E-learning: http://compassioninpolitics.wordpress.com/2009/06/05/top-future-trends-in-e-learning-and-educational-technology/ Consortium, T. N., Glenn, M. (2008). The future of higher education. Retrieved September 10, 2010, from nmc.org/pdf/Future-of-Higher-Ed-%28NMC%29.pdf

buy custom Macroeconomics essay

buy custom Macroeconomics essay Macroeconomics deals with the economy as a whole. The millions of individual microeconomic decisions of the people, businesses, and government in their totality represent a nations economy. Macroeconomics economic goals involve three conditions associated with mixed economy such as the full employment, the levels of stability as well as economic growth which have the society desires (Schumpeter, 2004). The government therefore has a duty of pursuing them through implementing economic policies. Other goals include balanced trade, economic freedom, equitable income distribution and stability of price level. There is no universal acceptance of the existing economic goals and they are also not complementary at all times (Lazear, 2000). Macroeconomics business cycle implies periods that usually keep on recurring and they are associated with recession at times and prosperity at other times and they may be widespread in the entire nation. There is a need of identifying them through the variations in seasons such as the absence of sales of heavy clothing in summer (Blaug, 2007). They also have secular trends on the long run especially in relation to the population such is the case with the baby boom. The phases evident in the business cycle include peak, contraction, the times of recession, the trough, recovery, as well as expansion. Retrenchment in the workplace is the best indicator of changes in the business cycle which mostly occurs at the time of recession (Harcourt, 2007). The economic variables in macroeconomics include the quantity, the quality as well as distribution. The implication of quality is the qualitative changes that take place in the processes of production (James, 2007). The occurrence of qualitative changes is at the time of the alteration of different price input as well as output (Baumol, 2007). The implication of distribution on the other hand is the series of the events whereby the unit prices related to the constant-quality products as well as the inputs have been altered resulting to the changes in the level of income. Buy custom Macroeconomics essay

Commonwealth Government's Work Choices Legislation Essay

Commonwealth Government's Work Choices Legislation - Essay Example It rationalized the existing classification structures so they remain relevant to the modern workplace relations system while recognizing the different skill sets of employees. Revitalized dismissal laws whereby the Government will protect all employees from unlawful termination and dismissal on discriminatory grounds such as race, colour, sex, union membership, pregnancy, etc. Any liberalization moves are bound to inconvenience some self-serving caucus who are the beneficiaries of non-competitive enterprise arrangement. In Australia it included Trade Unions, Business Community and opposition political parties who has the natural accumen to fish in muddled water. In a modern democratic set up such constitutional disputes finally land up in the highest court of law for legitimacy. The Australian High Court decreed this with a majority verdict in favour of the government. The organized working class consists of a large chunk of the population in any country. They mainly constitute the middle class and are the opinion makers and can exert envious influence on the polity of a nation. In a democratic country they constitute sizable vote bank, which a political party can ignore at their own peril. The successful Bolshevist Revolution, the decisive defeat of Communism in Germany with the help of organized labor movement, the progressive metamorphosis of American capitalism into a "welfare capitalism", etc. are indelible models where working class became important tools to usher in lasting impact on the contemporary society. Therefore, we see a deep-rooted nexus between political parties and trade unions all over the world. Theirs is a husband and wife relationship, indispensable to both. With mutual understanding and cooperation both can survive the travails of life; and any impudence on the part of one can destroy the prospects of both. In most modern de mocratic countries we see political parties with the imbibed philosophy and names of the working class struggle. Instances are many where trade union leaders have risen to positions to guide the destiny of their nation. It is therefore, inevitable for any ruling setup in a country to succumb to the influence of the organized labor unions. The intense lobbying by trade unions for the passage of The Employee Free Choices Act of America, by the US Law-Makers is a live example of the trade union domination over political parties. Recently, with Democrats gaining majority in the Congress the Bill was passed in the House of Representatives and is struggling to get past the Senate where Democrats do not have majority. It will certainly become a law after the next presidential elections due to strong labor pressures and lobbying. Background to the Work Choices Legislation The Liberal and National Coalition's 2004 Election Manifesto1 had committed to the electorate to introduce a "Flexible Workplace Relations" in the economic activities of the country.A New Workplace

Earned Value Management Research Paper Example | Topics and Well Written Essays - 750 words

Earned Value Management - Research Paper Example Due to features that allow Earned Value Management (EVM) to fuse scope, cost and schedule tools, it can accurately predict the project outcomes. Safe project forecasting allow for better planning ahead of time and to make necessary adjustments. Moreover, various studies show that project that use EVM techniques have a higher success rate than the projects that don’t use. In addition to these benefits, EVM has also proved useful in substantiating project disputes. Different project managers use EVM according to their specific project requirements; however certain features of EVM are considered essential and can be recognized as the defining criterion for EVM techniques. These implementation features are; The main difference between projects that use EVM and the ones that do not is quantifying processes and their performances. For instance, EVM projects set specific criteria to allocate numbers to any process and its relative performance. This helps in tracking and adjusting overall performance of the project. Usually at the end of each week, the project manager reviews the progress and adds together the planned values (PV) of each individual task to calculate the Earned Value (EV). This review can be done weekly, monthly, or according to the nature of the project. To understand the governing principles of EVM it would be helpful to know that every task of a project earns value. And translating these tasks into numbers helps in analyzing the performance and make appropriate adjustments. As a result, project managers can achieve better project forecasting. Project managers compare earned values with planned values and actual costs for reviewing performance. Such comparisons help project managers and the owners of the project to calculate their return on the money spent. Another feature of EVM that makes it convenient as well as efficient is its ability to measure physical performance in dollar amounts (Kidasa, 2005). This

Anyone interested in Scottish family and Scottish local history should Essay

Anyone interested in Scottish family and Scottish local history should be aware of the changes in legislation in the nineteenth - Essay Example However, there had been previous laws, which concerned the relief of the poor within the country before the enactment of the 1845 act. Nevertheless, this particular act is particularly important to the history of the Scottish local family in that it was wholly intended to empower the individual parishes to enumerate own poor. Moreover, besides just enumeration of the poor, the enactment of the law empowered the state to enquire more into the poverty status of the people.Through the enquiry, the state would understand the circumstances around the poverty, understand whether the ‘poor’ would be in a position to work and establish whether there existed other family members who would be depended on by the family for survival. A characteristic feature that existed in the Scottish law previously had been a poor rate or levy, which had been imposed within the state in order to assist the poor. However, therefore was the need to evaluate the effectiveness of the legislations as they were prior to the 1845 enactment of the legislation, which saw the amendments, which led to the 1845-act formulation. The act of 1845 had main provisions, which revolved around the establishment of a supervisory board whose mandate was to effect poor law system regulation. It also provided for retaining the already existing ‘parish based systems’ via Parochial boards (The National Archives of Scotland, para 3). The boards had also powers to regulate taxes. Outdoor relief services for the poor were meant to remain with an attention to building more poor houses for the sick. Moreover, the act empowered the inspector of the poor to legitimize the applications of relief to the poor. The effects of the enactment of the legislation saw the able-bodied poor segment of the population miss an automatic entitlement to the poor relief, as was the case previously in England. However, under the legislation, the poor had the capacity to engage legal procedures to appeal for poor relief denied on them. Nevertheless, in spite of such a promising legislation as it were, it suffered a major drawback on the fact that it lacked a framework to address outdoor relief mismanagement, which was very prevalent. The nineteenth century legislations had great impacts on the records to the Scottish local family and as such, anyone interested in Scottish family and Scottish local history should be aware of these changes in legislation. This paper therefore intends to discuss the specific changes brought about by the legislation and the impact brought about to the records. The previous regimes of legislation ware more open and inclusive where the disabled as well as the poor were entitled to assistance with the blind, orphans, the sick as well as the old having the priority over the assistance though the able bodied had special provision to the relief under special occasions (Milner, 2). Under such instances, the able bodied were included in the provision of the ‘occa sional’ poor during hard times. It was the responsibility of the Kirk sessions and the landowners to oversee dispensation of the relief within the rural areas whereas the town councils as well as magistrates over saw the process within the urban areas (Milner, 1; General Register office for Scotland, 1).1 Each parish took care of its own poor through church collections, voluntary donations as well as through fines inflicted on the convicted sinners (Mitchison, 109; Clark,

Organisational Learning and Knowledge Management at General Electric Essay

Organisational Learning and Knowledge Management at General Electric - Essay Example This is much higher than the industry average, due largely to the knowledge management systems in place at this multi-national enterprise. General Electric is a top-down, centralized management hierarchy with divisional management reporting to executive leadership at company headquarters, led by Chairman Jeffrey Immelt. In order to establish appropriate cost control and generalized leadership controls, the company requires this centralized organizational structure due to the interdependence between all divisions and the high volume of employees at GE. The centralized nature of General Electric somewhat confounds the traditionalist viewpoint of knowledge management systems, as it is generally recognised that in order to effectively manage knowledge, employees must be more interactive in decision-making through autonomous learning and job role functioning (Davenport, Jarvenpaa, and Beers, 1996; Swan, Scarbrough and Robertson, 2002). The centralized structure of General Electric is what prompted analysis of this particular business case as it defies the argument that a decentralized structure ensures more efficient knowledge management processes. In order to manage knowledge and promote organizational learning, GE relies on technology, experiential learning processes, the SECI model promoted by Nonaka, and bounded rationality as key approaches to facilitate KM practices. GE is governed by leadership that understands the complexities of multi-national business operations. Offers Jack Welch, previous CEO of GE, â€Å"you can’t manage what you can’t measure† (Seymour 2008: 28). Time constraints, the practical market environment and its unpredictability in certain markets, and the differing cultural dimensions of diverse employee populations create difficulty in creating concrete and time-sensitive decisions without recognizing the boundaries associated with rational decision-making. Thus, GE’s approach to knowledge management is based on p racticality rather than ideology which drives aspects of its cultural development focus and short-term business objective planning. This report highlights the knowledge management and learning practices at GE with a focus on the systems in place to promote such activities. GE cultures, systems, structure, and practices General Electric follows the SECI model which focuses on the relationship between socialization, externalization, combination, and internalization. Despite its centralized hierarchy, General Electric prides itself on its commitment to building positive interpersonal relationships between management and employees, building a culture of innovation, cooperation, team work, and loyalty. Thus, against the SECI model, GE is most closely focused on socialization in order to effectively manage knowledge and promote organizational learning. The knowledge that resides within GE is largely tacit, this being the knowledge that is largely intangible and attached closely to individ ual implicit expertise (Dinur 2011).

History of Christian Thought Final Exam Questions Essay

History of Christian Thought Final Exam Questions - Essay Example The issue of abortion has always been a sensitive subject which has given rise to a host of debates. If the human embryo is considered as a human entity, then of course no one has the authority to destroy it, not even the parents who have created it. On the other hand, if the embryo is viewed as a portion of human tissue or as a coagulation of human cells, then this gives rise to a new argument in the debate. As people are usually believed to be endowed with right of determining the fate of their tissues, they are justified to do whatever they wish with the human embryo. A couple who do not want children can either donate their already formed embryo to an infertile couple, or destroy the embryo altogether. Therefore, when human beings are accorded the â€Å"ownership rights† over their own tissues and physical body parts, the act of abortion finds a justification in such a case (Gunning, Szoke, p.198). 2. The prevailing laws do not recognize human beings as the owners of their own tissues or any parts of their body. This is known as the legislation of â€Å"No property in the Body†. In such a situation, how can people be considered to have an â€Å"ownership right† over their tissues? 1A. ... The reason is that even is we have property is tissue; there seem to be other overriding moral considerations. If we have ownership rights in tissues, this implies that people should be allowed to destroy their organs and tissues after their life ends when these are in the condition of saving other people’s lives. 3. People providing with the rights of ownership of tissues can lead to various problems in the society. People belonging to the lower middle class and those in need of money can find the selling of their own tissues as a legal profession which may endanger the cause of the humanity. Ownership of tissues would also make the people claim that their bodies parts comprised of various tissues are their own property and they had the right to sell it or do anything according to their wish. Like the trafficking of human, people will start making further inhuman activity and this time it will be their own body parts. The right of ownership of human tissues will definitely le ad to the trading activity and within a short period of time, it will eventually turnout to be a huge profitable business. The ownership right of tissues will result in the increase in number of killing of the unwanted embryo and will prevent the emergence of millions of life into the world. 4. 3A. the framing of the law regarding the ownership of rights will be done considering the social aspect and in that case will that create any further problems? And the killing of embryo is a punishable act in most of the countries and how will it further hamper the cause? 1N. in the presence of Laws and regulation the crimes rate have not taken a considerable decrease throughout the world the permission of providing the ownership right will

Supply Chain Analysis Essay Example | Topics and Well Written Essays - 4500 words

Supply Chain Analysis - Essay Example Some of the major benefit of a rapid response supply chain system that are discussed in the paper include timely delivery of the raw material and products, maximum security profit maximization and sales improvement. The logistics performance and inventory assessment is a vital responsibility of evaluators and logistics managers. Key measures used to assess the inventories and logistics performance that are discussed in the paper include Order fill rate, Accuracy of data to improve inventory management, Difference between the Quantity of Products Received and Quantity of Products Ordered, Logistics System Assessment Tool, Perfect order measurement, comprehensive and casual orientation of the logistic performance. The phenomena of local optimization that is brought up by the desire of the supply chain partners to maximize their profits adversely affect the optimality of the entire supply chain. This paper discusses how coordination, relationships among the partners, making sacrifices a nd compromises as major ways of mitigating the problem of local optimization. Supply chain management (SCM) entails the coordination of all the activities that are involved during the production of goods and services in a company. Some of the major aspects that are covered by SCM include transportation and storage of raw materials, controlling and monitoring work-in-progress as well as transportation of the final products from the factories to consumers. A rapid response supply chain system involves the various activities emulated by organizations in order to ensure that they are in line with the changing business atmosphere. Even though companies allocate significant financial resources to improve their supply chains, it is imperative to ensure that there is a positive linkage between partners in a supply chain. A rapid response supply chain system stipulates that there should exist

Organisational Learning and Knowledge Management at General Electric Essay

Organisational Learning and Knowledge Management at General Electric - Essay Example This is much higher than the industry average, due largely to the knowledge management systems in place at this multi-national enterprise. General Electric is a top-down, centralized management hierarchy with divisional management reporting to executive leadership at company headquarters, led by Chairman Jeffrey Immelt. In order to establish appropriate cost control and generalized leadership controls, the company requires this centralized organizational structure due to the interdependence between all divisions and the high volume of employees at GE. The centralized nature of General Electric somewhat confounds the traditionalist viewpoint of knowledge management systems, as it is generally recognised that in order to effectively manage knowledge, employees must be more interactive in decision-making through autonomous learning and job role functioning (Davenport, Jarvenpaa, and Beers, 1996; Swan, Scarbrough and Robertson, 2002). The centralized structure of General Electric is what prompted analysis of this particular business case as it defies the argument that a decentralized structure ensures more efficient knowledge management processes. In order to manage knowledge and promote organizational learning, GE relies on technology, experiential learning processes, the SECI model promoted by Nonaka, and bounded rationality as key approaches to facilitate KM practices. GE is governed by leadership that understands the complexities of multi-national business operations. Offers Jack Welch, previous CEO of GE, â€Å"you can’t manage what you can’t measure† (Seymour 2008: 28). Time constraints, the practical market environment and its unpredictability in certain markets, and the differing cultural dimensions of diverse employee populations create difficulty in creating concrete and time-sensitive decisions without recognizing the boundaries associated with rational decision-making. Thus, GE’s approach to knowledge management is based on p racticality rather than ideology which drives aspects of its cultural development focus and short-term business objective planning. This report highlights the knowledge management and learning practices at GE with a focus on the systems in place to promote such activities. GE cultures, systems, structure, and practices General Electric follows the SECI model which focuses on the relationship between socialization, externalization, combination, and internalization. Despite its centralized hierarchy, General Electric prides itself on its commitment to building positive interpersonal relationships between management and employees, building a culture of innovation, cooperation, team work, and loyalty. Thus, against the SECI model, GE is most closely focused on socialization in order to effectively manage knowledge and promote organizational learning. The knowledge that resides within GE is largely tacit, this being the knowledge that is largely intangible and attached closely to individ ual implicit expertise (Dinur 2011).

Supply Chain Analysis Essay Example | Topics and Well Written Essays - 4500 words

Supply Chain Analysis - Essay Example Some of the major benefit of a rapid response supply chain system that are discussed in the paper include timely delivery of the raw material and products, maximum security profit maximization and sales improvement. The logistics performance and inventory assessment is a vital responsibility of evaluators and logistics managers. Key measures used to assess the inventories and logistics performance that are discussed in the paper include Order fill rate, Accuracy of data to improve inventory management, Difference between the Quantity of Products Received and Quantity of Products Ordered, Logistics System Assessment Tool, Perfect order measurement, comprehensive and casual orientation of the logistic performance. The phenomena of local optimization that is brought up by the desire of the supply chain partners to maximize their profits adversely affect the optimality of the entire supply chain. This paper discusses how coordination, relationships among the partners, making sacrifices a nd compromises as major ways of mitigating the problem of local optimization. Supply chain management (SCM) entails the coordination of all the activities that are involved during the production of goods and services in a company. Some of the major aspects that are covered by SCM include transportation and storage of raw materials, controlling and monitoring work-in-progress as well as transportation of the final products from the factories to consumers. A rapid response supply chain system involves the various activities emulated by organizations in order to ensure that they are in line with the changing business atmosphere. Even though companies allocate significant financial resources to improve their supply chains, it is imperative to ensure that there is a positive linkage between partners in a supply chain. A rapid response supply chain system stipulates that there should exist

Ethnic Groups and Discrimination Essay Example for Free

Ethnic Groups and Discrimination Essay I belong to the White ethnic group which was responsible for the colonization of North America. While I am part of the White ethnic group, my family immigrated to the United States from Germany quite some time after the major colonization of North America. When most people think about the colonization of North America they think of White people on the Mayflower landing on Plymouth Rock. While the pilgrims did colonize what is now referred to as New England, the Spanish were actually the first to colonize North America. No matter who first colonized North America, this colonization caused an influx of immigrants that asserted their dominance over the native people. This colonization was also the root cause of slavery being introduced to this New World. Pilgrims are most notably identified as coming to North America to escape religious persecution. The ironic part of the colonization is that the pilgrims forced their religion on those native to North America. It is important to note that this may be one of the first indications of future ethnic and racial problems that would caused by the colonization of North America. I dont think people normally think about racism happening to Caucasians. Unfortunately it is very common for racism to happen to all ethnic groups in the U. S. Caucasian racism and prejudice against other ethnic and racial groups always seem to get the most publicity. It would be better to broaden our view of prejudice and racism so that we could get the whole story. I think that the Caucasian group had brought most of this negative attention on itself. Historically the U. S. has been dominated by Caucasians, which means this group doesnt have as much to worry about restrictions due to ethnicity or racial group. If we break down the Caucasian group even further we can see that this is even truer for the males, which I am, of this group. Male Caucasians have long been the dominant force in U. S. society. The majority of restrictions placed on females and ethnic groups have been enforced by Male Caucasians. The most notable Caucasian discrimination has been against African Americans. African Americans were largely used for slave labor during the beginning of the U. S. Going from slave to equal isnt easy, in both occurrence and acceptance from the former dominant or controlling group. This dominant position can be seen as a major reason why the view of discrimination is still focused on Caucasians. Since the Caucasian males of the past have put restrictions on most other ethnic groups, this wrong was attempted to be undone by Affirmative Action laws (Fullinwider, Robert). While most people see Affirmative Action as being helpful, it has also caused discrimination against Caucasian males. Some government agencies require a quota on hiring certain ethnic groups (this included female Caucasians). This can cause a job candidate that has hirer qualifications to be passed over just to fulfill a quota. I have seen this happen to my father while he was applying for a firefighter/EMT position. You can easily see the Caucasian male dominance by noticing the dual labor market effect. I see it more as a multiple labor market since I would also include female Caucasians as another labor market. Immigrants from Mexico often enter into a portion of this multiple labor market, most notably the farming community. Whether it is farming, manual labor, or the lower-end service sector it seems that it seems more acceptable to Caucasians for other ethnic groups to occupy these types of jobs. When the other ethnic groups occupy positions normally held by Caucasian males, we often see a limitation in their ability to progress in that profession (glass ceiling). If you look at the breakdown of people who run companies you will see this is dominated by Caucasians males, followed by males of the other ethnic groups, then females of all ethnic groups. Discrimination isnt only apparent in the job market, but in how companies invest in certain areas. It is seen in our response to what is happening in other areas of cities or areas of the country. We have slums and ghettos that dont get investment monies to fix them up due to the lower class segregation. We have other areas occupied by a high number of non-Caucasians that dont get investments just because of their ethnicity. New Orleans is a perfect example of all of these inequalities. It was a city segregated by race, ethnicity, and social class standing. The devastation caused by hurricane Katrina happened to people who couldnt afford to get out on their own, and was compounded by the predominantly Caucasian governments lack of response (arguably due to the racial differences between U. S. leaders and with the people effected by the disaster). I dont feel that I fit in with the standard culture for my Caucasian ethnic group or the U. S. mainstream culture. I dont participate in any religions, as I believe in myself and science that can be proved. I dont feel that I am or need to be better than any other ethnic group. I couldnt care less about what style is popular or what haircuts are in. I just try to be myself and try to ignore things that try to sway my opinions. Instead of taking someones word for something I would rather research and come to my own decision (almost to a fault). I think it is better to be different than a lemming following the crowd running off the cliff. References Fullinwider, Robert (2005). Affirmative Action. Retrieved February 1, 2006 from http://plato. stanford. edu/entries/affirmative-action/.

Underwater Acoustic Sensor Network (UASN)

Underwater Acoustic Sensor Network (UASN) CHAPTER1: Introduction Most of the earth surface is composed of water including fresh water from river, lakes etc and salt water from the sea. There are still many un-explored areas for such places. This needs significant research efforts and good communication systems. Wireless sensor network in aqueous medium has the ability to explore the underwater environment in details. For all applications of underwater, a good communication system as well as an effective routing protocol is needed. This will enable the underwater devices to communicate precisely. Underwater propagation speed varies with temperature, salinity and depth. By varying the underwater propagation speed at different depth, two scenarios can be achieved accurately namely: shallow and deep water. Shallow water consists of depth less than 200m and cylinder spreading. Deep water consists of depth greater or equal to 200 m and spherical spreading. In both shallow and deep water, different ambient noise and different spreading factor is applied. CHAPTER 2: Study of Underwater Acoustic Sensor Network (UASN) Application of UASN Wireless sensor network in aqueous medium also known as underwater sensor network has enabled a broad range of applications including: Environmental Monitoring Underwater sensor network can be used to monitor pollution like chemical, biological such as tracking of fish or micro-organisms, nuclear and oil leakage pollutions in bays, lakes or rivers [1]. Underwater sensor network can also be used to improve weather forecast, detect climate change, predict the effect of human activities on marine ecosystems, ocean currents and temperature change e.g. the global warming effect to ocean. Under Ocean Exploration Exploring minerals, oilfields or reservoir, determine routes for laying undersea cables and exploration valuable minerals can be done with such underwater sensor network. Disaster Prevention Sensor network that measure seismic activity from remote locations can provide tsunami warning to coastal areas, or study the effects of submarine earthquakes (seaquakes) [2] Equipment Monitoring Long-term equipment monitoring may be done with pre-installed infrastructure. Short-term equipment monitoring shares many requirements of long-term seismic monitoring, including the need for wireless (acoustic) communication, automatic configuration into a multihop network, localization (and hence time synchronization), and energy efficient operation Mine Reconnaissance By using acoustic sensors and optical sensors together, mine detection can be accomplished quickly and effectively. Assisted Monitoring Sensor can be used to discover danger on the seabed, locate dangerous rocks or shoals in shallow waters, mooring position, submerged wrecks and to perform bathymetry profiling. Information collection The main goal of communication network is the exchange of information inside the network and outside the network via a gateway or switch center. This application is used to share information among nodes and autonomous underwater vehicles. Characteristic of UASN Underwater Acoustic Networks (UANs), including but not limited to, Underwater Acoustic Sensor Networks (UASNs) and Autonomous Underwater Vehicle Networks (AUVNs) , are defined as networks composed of more than two nodes, using acoustic signals to communicate, for the purpose of underwater applications. UASNs and AUVNs are two important kinds of UANs. The former is composed of many sensor nodes, mostly for a monitoring purpose. The nodes are usually without or with limited capacity to move. The latter is composed of autonomous or unmanned vehicles with high mobility, deployed for applications that need mobility, e.g., exploration. An UAN can be an UASN, or an AUVN, or a combination of both. Acoustic communications, on the other hands, is defined as communication methods from one point to another by using acoustic signals. Network structure is not formed in acoustic point-to-point communications. Sound travels best through the water in comparison with electromagnetic waves and optical signals. Acoustic signal is sound signal waveform, usually produced by sonar for underwater applications. Acoustic signal processing extracts information from acoustic signals in the presence of noise and uncertainty. Underwater acoustic communications are mainly influenced by path loss, noise, multi-path, Doppler spread, and high and variable propagation delay. All these factors determine the temporal and spatial variability of the acoustic channel, and make the available bandwidth of the Underwater Acoustic channel (UW-A) limited and dramatically dependent on both range and frequency. Long-range systems that operate over several tens of kilometers may have a bandwidth of only a few kHz, while a short-range system operating over several tens of meters may have more than a hundred kHz bandwidth. These factors lead to low bit rate. Underwater acoustic communication links can be classified according to their range as very long, long, medium, short, and very short links. Acoustic links are also roughly classified as vertical and horizontal, according to the direction of the sound ray. Their propagation characteristics differ consistently, especially with respect to time dispersion, multi-path spreads, and delay variance. Acoustic signal is the only physical feasible tool that works in underwater environment. Compared with it, electromagnetic wave can only travel in water with short distance due to the high attenuation and absorption effect in underwater environment. It is found that the absorption of electromagnetic energy in sea water is about 45Ãâ€" ?f dB per kilometer, where f is frequency in Hertz; In contrast, the absorption of acoustic signal over most frequencies of interest is about three orders of magnitude lower [40]. Hereafter the factors that influence acoustic communications is analyzed in order to state the challenges posed by the underwater channels for underwater sensor networking. These include: Path loss Attenuation is mainly provoked by absorption due to conversion of acoustic energy into heat, which increases with distance and frequency. It is also caused by scattering a reverberation (on rough ocean surface and bottom), refraction, and dispersion (due to the displacement of the reflection point caused by wind on the surface). Water depth plays a key role in determining the attenuation. Geometric Spreading is the spreading of sound energy as a result of the expansion of the wavefronts. It increases with the propagation distance and is independent of frequency. There are two common kinds of geometric spreading: spherical (omni-directional point source), and cylindrical (horizontal radiation only). Noise Man made noise is mainly caused by machinery noise (pumps, reduction gears, power plants, etc.), and shipping activity (hull fouling, animal life on hull, cavitations), especially in areas encumbered with heavy vessel traffic. Ambient Noise is related to hydrodynamics (movement of water including tides, current, storms, wind, rain, etc.), seismic and biological phenomena. Multi-path Multi-path propagation may be responsible for severe degradation of the acoustic communication signal, since it generates Inter-Symbol Interference (ISI). The multi-path geometry depends on the link configuration. Vertical channels are characterized by little time dispersion, whereas horizontal channels may have extremely long multi-path spreads. The extent of the spreading is a strong function of depth and the distance between transmitter and receiver. High delay and delay variance The propagation speed in the UW-A channel is five orders of magnitude lower than in the radio channel. This large propagation delay (0.67 s/km) can reduce the throughput of the system considerably. The very high delay variance is even more harmful for efficient protocol design, as it prevents from accurately estimating the round trip time (RTT), which is the key parameter for many common communication protocols. Doppler spread The Doppler frequency spread can be significant in UW-A channels, causing degradation in the performance of digital communications: transmissions at a high data rate because many adjacent symbols to interfere at the receiver, requiring sophisticated signal processing to deal with the generated ISI. The Doppler spreading generates: a simple frequency translation, which is relatively easy for a receiver to compensate for a continuous spreading of frequencies, which constitutes a non-shifted signal, which is more difficult for a receiver to compensate for. If a channel has a Doppler spread with bandwidth B and a signal has symbol duration T, then there are approximately BT uncorrelated samples of its complex envelope. When BT is much less than unity, the channel is said to be under spread and the effects of the Doppler fading can be ignored, while, if greater than unity, it is overspread. Most of the described factors are caused by the chemical-physical properties of the water medium such as temperature, salinity and density, and by their spatio-temporal variations. These variations, together with the wave guide nature of the channel, because the acoustic channel to be temporally and spatially variable. In particular, the horizontal channel is by far more rapidly varying than the vertical channel, in both deep and shallow water. CHAPTER 3: Network Architecture Underwater sensor nodes: The underwater sensor nodes are deployed on the sea floor anchored to the ocean bottom [32]. The sensors are equipped with floating buoys to push the nodes upwards, thus they are relatively stationary nodes [3]. Using acoustic links, they relay data to underwater sink directly or via multi-hop path. Underwater sink nodes: Underwater sink nodes take charge of collecting data of underwater sensors deployed on the ocean bottom and then send to the surface sink node. They may be equipped with vertical and horizontal acoustic transducers. The horizontal transceiver is used to collect the sensors data and the vertical transceiver provides transmitting link between underwater sink and the surface sink node. Surface sink node: Surface sink node is attached on a floating buoy with satellite, radio frequency (RF) or cell phone technology to transmit data to shore in real time. 2D Model A reference architecture for two-dimensional underwater networks is shown in Figure. 1. A group of sensor nodes are anchored to the deep of the ocean. Underwater sensor nodes are interconnected to one or more underwater gateways by means of wireless acoustic links. Underwater-gateways are network devices in charge of relaying data from the ocean bottom network to a surface station. To achieve this objective, they are equipped with two acoustic transceivers, namely a vertical and a horizontal transceiver. The horizontal transceiver is used by the underwater-gateway to communicate with the sensor nodes in order to: send commands and configuration data to the sensors (underwater -gateway to sensors); collect monitored data (sensors to underwater -gateway). The vertical link is used by the underwater -gateways to relay data to a surface station. In deep water applications, vertical transceivers must be long range transceivers. The surface station is equipped with an acoustic transceiver that is able to handle multiple parallel communications with the deployed underwater -gateways. It is also endowed with a long range RF and/or satellite transmitter to communicate with the onshore sink (os-sink) and/or to a surface sink (s-sink). In shallow water, bottom-deployed sensors/modems may directly communicate with the surface buoy, with no specialized bottom node (underwater -gateway). 3D Model Three-dimensional underwater networks are used to detect and observe phenomena that cannot be adequately observed by means of ocean bottom sensor nodes, i.e., to perform cooperative sampling of the 3D ocean environment. In three-dimensional underwater networks, sensor nodes float at different depths to observe a phenomenon. In this architecture, given in Figure 2, each sensor is anchored to the ocean bottom and equipped with a floating buoy that can be inflated by a pump. The buoy pushes the sensor towards the ocean surface. The depth of the sensor can then be regulated by adjusting the length of the wire that connects the sensor to the anchor, by means of an electronically controlled engine that resides on the sensor. Sensing and communication coverage in a 3D environment are rigorously investigated in [8]. The diameter, minimum and maximum degree of the reachability graph that describes the network are derived as a function of the communication range, while different degrees of cov erage for the 3D environment are characterized as a function of the sensing range. 3D Model with AUV The above figure represents the third type of network architecture which consist of sensor nodes and Autonomous Underwater Vehicles (AUV) which act as mobile sensor nodes for ocean monitoring, underwater resource study, etc. CHAPTER 4: Differences between underwater and terrestrial Sensor Network An underwater acoustic channel is different from a ground-based radio channel from many aspects, including: Bandwidth is extremely limited. The attenuation of acoustic signal increases with frequency and range [6] [10]. Consequently, the feasible band is extremely small. For example, a short range system operating over several tens of meters may have available bandwidth of a hundred kHz; a medium-range system operating over several kilometers has a bandwidth on the order of ten kHz; and a long-range system operating over several tens of kilometers is limited to only a few kHz of bandwidth [11]. Propagation delay is long. The transmission speed of acoustic signals in salty water is around 1500 meter/s [22], which is a difference of five orders of magnitude lower than the speed of electromagnetic wave in free space. Correspondently, propagation delay in an underwater channel becomes significant. This is one of the essential characteristics of underwater channels and has profound implications on localization and time synchronization. The channel impulse response is not only spatially varied but also temporarily varied. The channel characteristics vary with time and highly depend on the location of the transmitter and receiver. The fluctuation nature of the channel causes the received signals easily distorted. There are two types of propagation paths: macro-multipaths, which are the deterministic propagation paths; and micro-multipath, which is a random signal fluctuation. The macro-multipaths are caused by both reflection at the boundaries (bottom, surface and any object in the water) and bending. Inter- Symbol Interference (ISI) thus occurs. Compared with the spread of its ground-based counterpart, which is on the order of several symbol intervals, ISI spreading in an underwater acoustic channel is several tens or hundred of symbol intervals for moderate to high data rate in the horizontal channel. Micro-multipath fluctuations are mainly caused by surface wave, which contributes the most to the time variability of shallow water channel. In deep water, internal waves impact the single-path random fluctuations [12][13]. Probability of bit error is much higher and temporary loss of connectivity (shadow zone) sometimes occurs, due to the extreme characteristics of the channel. Cost. While terrestrial sensor nodes are expected to become increasingly inexpensive, underwater sensors are expensive devices. This is especially due to the more complex underwater transceivers and to the hardware protection needed in the extreme underwater environment. Also, because of the low economy of scale caused by a small relative number of suppliers, underwater sensors are characterized by high cost. Deployment. While terrestrial sensor networks are densely deployed, in underwater, the deployment is generally more sparse. Power. The power needed for acoustic underwater communications is higher than in terrestrial radio communications because of the different physical layer technology (acoustic vs. RF waves), the higher distances, and more complex signal processing techniques implemented at the receivers to compensate for the impairments of the channel. Memory. While terrestrial sensor nodes have very limited storage capacity, underwater-sensors may need to be able to do some data caching as the underwater channel may be intermittent. Spatial Correlation. While the readings from terrestrial sensors are often correlated, this is more unlikely to happen in underwater networks due to the higher distance among sensors. CHAPTER 5: Layered of UASN The underwater architecture network consists of five layers, application, transport, network, data link and physical layer as shown in the figure below. As typical underwater systems have limited processing capability, the protocol has been kept as simple as possible without significantly compromising performance. The underwater sensor network specifications currently do not include any recommendations for authentication and encryption. These may be easily implemented at the application layer or via a spreading scheme at the physical layer. Each layer is described by a SAPI. The SAPI is defined in terms of messages being passed to and from the layer. The clients (usually higher layers) of a layer invoke the layer via a request (REQ). The layer responds to each REQ by a response (RSP). Errors are reported via an ERR RSP with error codes. If the layer needs to send unsolicited messages to the client, it does so via a notification (NTF). A layer communicates logically with its peer layer via protocol data units (PDU). As the peer-to-peer communication is symmetric, a layer may send a REQ PDU to its peer layer at any time. It would optionally respond to such a PDU with a RSP PDU. This is logically depicted in Figure below It may be desirable in some cases, that non-neighboring layers communicate with each other to achieve cross-layer optimization. This may be implemented by allowing REQ and RSP PDUs between any two layers in the protocol stack. The underwater sensor network specifications define detailed message structures for all SAPI messages. These message structures include message identifiers, data formats to be used, parameters and their possible values Physical layer The physical layer provides framing, modulation and error correction capability (via FEC). It provides primitives for sending and receiving packets. It may also provide additional functionality such as parameter settings, parameter recommendation, carrier sensing, etc. At first underwater channel development was based on non-coherent frequency shift keying (FSK) modulation, since it relies on energy detection. Thus, it does not require phase tracking, which is a very difficult task mainly because of the Doppler-spread in the underwater acoustic channel. Although non-coherent modulation schemes are characterized by high power efficiency, their low bandwidth efficiency makes them unsuitable for high data rate multiuser networks. Hence, coherent modulation techniques have been developed for long-range, high-throughput systems. In the last years, fully coherent modulation techniques, such as phase shift keying (PSK) and quadrature amplitude modulation (QAM), have become practical due to the availability of powerful digital processing. Channel equalization techniques are exploited to leverage the effect of the inter-symbol interference (ISI), instead of trying to avoid or suppress it. Decision-feedback equalizers (DFEs) track the complex, relatively slowly varying channel response and thus provide high throughput when the channel is slowly varying. Conversely, when the channel varies faster, it is necessary to combine the DFE with a Phase Locked Loop (PLL) [9], which estimates and compensates for the phase offset in a rapid, stable manner. The use of decision feedback equalization and phase-locked loops is driven by the complexity and time variability of ocean channel impulse responses. Differential phase shift keying (DPSK) serves as an intermediate solution between incoherent and fully coherent systems in terms of bandwidth efficiency. DPSK encodes information relative to the previous symbol rather than to an arbitrary fixed reference in the signal phase and may be referred to as a partially coherent modulation. While this strategy substantially alleviates carrier phase-tracking requirements, the penalty is an increased error probability over PSK at an equivalent data rate. Another promising solution for underwater communications is the orthogonal frequency division multiplexing (OFDM) spread spectrum technique, which is particularly efficient when noise is spread over a large portion of the available bandwidth. OFDM is frequently referred to as multicarrier modulation because it transmits signals over multiple sub-carriers simultaneously. In particular, sub-carriers that experience higher SNR, are allotted with a higher number of bits, whereas less bits are allotted to sub-carriers experiencing attenuation, according to the concept of bit loading, which requires channel estimation. Since the symbol duration for each individual carrier increases, OFDM systems perform robustly in severe multi-path environments, and achieve a high spectral efficiency. Many of the techniques discussed above require underwater channel estimation, which can be achieved by means of probe packets [17]. An accurate estimate of the channel can be obtained with a high probing rate and/or with a large probe packet size, which however result in high overhead, and in the consequent drain of channel capacity and energy. Data link layer (MAC layer) The data link layer provides single hop data transmission capability; it will not be able to transmit a packet successfully if the destination node is not directly accessible from the source node. It may include some degree of reliability. It may also provide error detection capability (e.g. CRC check). In case of a shared medium, the data link layer must include the medium access control (MAC) sub-layer. Frequency division multiple access (FDMA) is not suitable for underwater sensor network due to the narrow bandwidth in underwater acoustic channels and the vulnerability of limited band systems to fading and multipath. Time division multiple access (TDMA) shows limited bandwidth efficiency because of the long time guards required in the underwater acoustic channel. In fact, long time guards must be designed to account for the large propagation delay and delay variance of the underwater channel in order to minimize packet collisions from adjacent time slots. Moreover, the variable delay makes it very challenging to realize a precise synchronization, with a common timing reference, which is required for TDMA. Carrier sense multiple access (CSMA) prevents collisions with the ongoing transmission at the transmitter side. To prevent collisions at the receiver side, however, it is necessary to add a guard time between transmissions dimensioned according to the maximum propagation delay in the network. This makes the protocol dramatically inefficient for underwater acoustic sensor network. The use of contention-based techniques that rely on handshaking mechanisms such as RTS/ CTS in shared medium access is impractical in underwater, for the following reasons: large delays in the propagation of RTS/CTS control packets lead to low throughput; due to the high propagation delay of underwater acoustic channels, when carrier sense is used, as in 802.11, it is more likely that the channel be sensed idle while a transmission is ongoing, since the signal may not have reached the receiver yet; the high variability of delay in handshaking packets makes it impractical to predict the start and finish time of the transmissions of other stations. Thus, collisions are highly likely to occur. Code division multiple access (CDMA) is quite robust to frequency selective fading caused by underwater multi-paths, since it distinguishes simultaneous signals transmitted by multiple devices by means of pseudo-noise codes that are used for spreading the user signal over the entire available band. CDMA allows reducing the number of packet retransmissions, which results in decreased battery consumption and increased network throughput. In conclusion, although the high delay spread which characterizes the horizontal link in underwater channels makes it difficult to maintain synchronization among the stations, especially when orthogonal code techniques are used [17], CDMA is a promising multiple access technique for underwater acoustic networks. This is particularly true in shallow water, where multi-paths and Doppler- spreading plays a key role in the communication performance. Network layer (Routing) The network layer is in charge of determining the path between a source (the sensor that samples a physical phenomenon) and a destination node (usually the surface station). In general, while many impairments of the underwater acoustic channel are adequately addressed at the physical and data link layers, some other characteristics, such as the extremely long propagation delays, are better addressed at the network layer. Basically, there are two methods of routing. The first one is virtual circuit routing and the second one is packet-switch routing. In virtual circuit routing, the networks use virtual circuits to decide on the path at the beginning of the network operation. Virtual-circuit-switch routing protocols can be a better choice for underwater acoustic networks. The reasons are: Underwater acoustic networks are typical asymmetric instead of symmetric. However, packet switched routing protocols are proposed for symmetric network architecture; Virtual-circuit-switch routing protocols work robust against link failure, which is critical in underwater environment; and Virtual-circuit-switch routing protocols have less signal overhead and low latency, which are needed for underwater acoustic channel environment. However, virtual-circuit-switch routing protocols usually lack of flexibility. In packet-switch routing, every node that is part of the transmission makes its own routing decision, i.e., decides its next hop to relay the packet. Packet-switch routing can be further classified into Proactive routing, Reactive and geographical routing protocols. Most routing protocols for ground-based wireless networks are packet-switch based. Proactive routing protocols attempt to minimize the message latency by maintaining up-to-date routing information at all times from each node to any other node. It broadcasts control packets that contain routing table information. Typical protocols include Destination Sequence Distance Vector (DSDV) [28] and Temporally Ordered Routing Algorithm (TORA). However, proactive routing protocols provoke a large signaling overhead to establish routes for the first time and each time the network topology changes. It may not be a good fit in underwater environment due to the high probability of link failure and extremely limited bandwidth there. Reactive routing protocols only initiate a route discovery process upon request. Correspondently, each node does not need to maintain a sizable look-up table for routing. This kind of routing protocols is more suitable for dynamic environment like ad hoc wireless networks. Typical protocol examples are Ad hoc On-demand Distance Vector (AODV) [23], and Dynamic Source Routing (DSR) [27]. The shortage of reactive routing protocols is its high latency to establish routing. Similar to its proactive counterpart, flooding of control packets to establish paths is needed, which brings significant signal overhead. The high latency could become much deteriorated in underwater environment because of the much slower propagation speed of acoustic signal compared with the radio wave in the air. Geographic routing (also called georouting or position-based routing) is a routing principle that relies on geographic position information. It is mainly proposed for wireless networks and based on the idea that the source sends a message to the geographic location of the destination instead of using the network address. Geographic routing requires that each node can determine its own location and that the source is aware of the location of the destination. With this information a message can be routed to the destination without knowledge of the network topology or a prior route discovery. Transport layer A transport layer protocol is needed in underwater sensor network not only to achieve reliable collective transport of event features, but also to perform flow control and congestion control. The primary objective is to save scarce sensor resources and increase the network efficiency. A reliable transport protocol should guarantee that the applications be able to correctly identify event features estimated by the sensor network. Congestion control is needed to prevent the network from being congested by excessive data with respect to the network capacity, while flow control is needed to avoid that network devices with limited memory are overwhelmed by data transmissions. Most existing TCP implementations are unsuited for the underwater environment, since the flow control functionality is based on a window- based mechanism that relies on an accurate esteem of the round trip time (RTT), which is twice the end-to-end delay from source to destination. Rate-based transport protocols seem also unsuited for this challenging environment. They still rely on feedback control messages sent back by the destination to dynamically adapt the transmission rate, i.e., to decrease the transmission rate when packet loss is experienced or to increase it otherwise. The high delay and delay variance can thus cause instability in the feedback control. Furthermore, due to the unreliability of the acoustic channel, it is necessary to distinguish between packet losses due to the high bit error rate of the acoustic channel, from those caused by packets being dropped from the queues of sensor nodes due to network congestion. In terrestrial, assume that congestion is the only cause for packet loss and the solution lies on decreasing the transmission rate, but in underwater sensor network if the packet loss is due to bad channel then the transmission rate should not be decreased to preserve throughput efficiency. Transport layer functionalities can be tightly integrated with data link layer functionalities in a cross-layer module. The purpose of such an integrated module is to make the information about the condition of the variable underwater channel available also at the transport layer. In fact, usually the state of the channel is known only at the physical and channel access sub-layers, while the design principle of layer separation makes this information transparent to the higher layers. This integration allows maximizing the Underwater Acoustic Sensor Network (UASN) Underwater Acoustic Sensor Network (UASN) CHAPTER1: Introduction Most of the earth surface is composed of water including fresh water from river, lakes etc and salt water from the sea. There are still many un-explored areas for such places. This needs significant research efforts and good communication systems. Wireless sensor network in aqueous medium has the ability to explore the underwater environment in details. For all applications of underwater, a good communication system as well as an effective routing protocol is needed. This will enable the underwater devices to communicate precisely. Underwater propagation speed varies with temperature, salinity and depth. By varying the underwater propagation speed at different depth, two scenarios can be achieved accurately namely: shallow and deep water. Shallow water consists of depth less than 200m and cylinder spreading. Deep water consists of depth greater or equal to 200 m and spherical spreading. In both shallow and deep water, different ambient noise and different spreading factor is applied. CHAPTER 2: Study of Underwater Acoustic Sensor Network (UASN) Application of UASN Wireless sensor network in aqueous medium also known as underwater sensor network has enabled a broad range of applications including: Environmental Monitoring Underwater sensor network can be used to monitor pollution like chemical, biological such as tracking of fish or micro-organisms, nuclear and oil leakage pollutions in bays, lakes or rivers [1]. Underwater sensor network can also be used to improve weather forecast, detect climate change, predict the effect of human activities on marine ecosystems, ocean currents and temperature change e.g. the global warming effect to ocean. Under Ocean Exploration Exploring minerals, oilfields or reservoir, determine routes for laying undersea cables and exploration valuable minerals can be done with such underwater sensor network. Disaster Prevention Sensor network that measure seismic activity from remote locations can provide tsunami warning to coastal areas, or study the effects of submarine earthquakes (seaquakes) [2] Equipment Monitoring Long-term equipment monitoring may be done with pre-installed infrastructure. Short-term equipment monitoring shares many requirements of long-term seismic monitoring, including the need for wireless (acoustic) communication, automatic configuration into a multihop network, localization (and hence time synchronization), and energy efficient operation Mine Reconnaissance By using acoustic sensors and optical sensors together, mine detection can be accomplished quickly and effectively. Assisted Monitoring Sensor can be used to discover danger on the seabed, locate dangerous rocks or shoals in shallow waters, mooring position, submerged wrecks and to perform bathymetry profiling. Information collection The main goal of communication network is the exchange of information inside the network and outside the network via a gateway or switch center. This application is used to share information among nodes and autonomous underwater vehicles. Characteristic of UASN Underwater Acoustic Networks (UANs), including but not limited to, Underwater Acoustic Sensor Networks (UASNs) and Autonomous Underwater Vehicle Networks (AUVNs) , are defined as networks composed of more than two nodes, using acoustic signals to communicate, for the purpose of underwater applications. UASNs and AUVNs are two important kinds of UANs. The former is composed of many sensor nodes, mostly for a monitoring purpose. The nodes are usually without or with limited capacity to move. The latter is composed of autonomous or unmanned vehicles with high mobility, deployed for applications that need mobility, e.g., exploration. An UAN can be an UASN, or an AUVN, or a combination of both. Acoustic communications, on the other hands, is defined as communication methods from one point to another by using acoustic signals. Network structure is not formed in acoustic point-to-point communications. Sound travels best through the water in comparison with electromagnetic waves and optical signals. Acoustic signal is sound signal waveform, usually produced by sonar for underwater applications. Acoustic signal processing extracts information from acoustic signals in the presence of noise and uncertainty. Underwater acoustic communications are mainly influenced by path loss, noise, multi-path, Doppler spread, and high and variable propagation delay. All these factors determine the temporal and spatial variability of the acoustic channel, and make the available bandwidth of the Underwater Acoustic channel (UW-A) limited and dramatically dependent on both range and frequency. Long-range systems that operate over several tens of kilometers may have a bandwidth of only a few kHz, while a short-range system operating over several tens of meters may have more than a hundred kHz bandwidth. These factors lead to low bit rate. Underwater acoustic communication links can be classified according to their range as very long, long, medium, short, and very short links. Acoustic links are also roughly classified as vertical and horizontal, according to the direction of the sound ray. Their propagation characteristics differ consistently, especially with respect to time dispersion, multi-path spreads, and delay variance. Acoustic signal is the only physical feasible tool that works in underwater environment. Compared with it, electromagnetic wave can only travel in water with short distance due to the high attenuation and absorption effect in underwater environment. It is found that the absorption of electromagnetic energy in sea water is about 45Ãâ€" ?f dB per kilometer, where f is frequency in Hertz; In contrast, the absorption of acoustic signal over most frequencies of interest is about three orders of magnitude lower [40]. Hereafter the factors that influence acoustic communications is analyzed in order to state the challenges posed by the underwater channels for underwater sensor networking. These include: Path loss Attenuation is mainly provoked by absorption due to conversion of acoustic energy into heat, which increases with distance and frequency. It is also caused by scattering a reverberation (on rough ocean surface and bottom), refraction, and dispersion (due to the displacement of the reflection point caused by wind on the surface). Water depth plays a key role in determining the attenuation. Geometric Spreading is the spreading of sound energy as a result of the expansion of the wavefronts. It increases with the propagation distance and is independent of frequency. There are two common kinds of geometric spreading: spherical (omni-directional point source), and cylindrical (horizontal radiation only). Noise Man made noise is mainly caused by machinery noise (pumps, reduction gears, power plants, etc.), and shipping activity (hull fouling, animal life on hull, cavitations), especially in areas encumbered with heavy vessel traffic. Ambient Noise is related to hydrodynamics (movement of water including tides, current, storms, wind, rain, etc.), seismic and biological phenomena. Multi-path Multi-path propagation may be responsible for severe degradation of the acoustic communication signal, since it generates Inter-Symbol Interference (ISI). The multi-path geometry depends on the link configuration. Vertical channels are characterized by little time dispersion, whereas horizontal channels may have extremely long multi-path spreads. The extent of the spreading is a strong function of depth and the distance between transmitter and receiver. High delay and delay variance The propagation speed in the UW-A channel is five orders of magnitude lower than in the radio channel. This large propagation delay (0.67 s/km) can reduce the throughput of the system considerably. The very high delay variance is even more harmful for efficient protocol design, as it prevents from accurately estimating the round trip time (RTT), which is the key parameter for many common communication protocols. Doppler spread The Doppler frequency spread can be significant in UW-A channels, causing degradation in the performance of digital communications: transmissions at a high data rate because many adjacent symbols to interfere at the receiver, requiring sophisticated signal processing to deal with the generated ISI. The Doppler spreading generates: a simple frequency translation, which is relatively easy for a receiver to compensate for a continuous spreading of frequencies, which constitutes a non-shifted signal, which is more difficult for a receiver to compensate for. If a channel has a Doppler spread with bandwidth B and a signal has symbol duration T, then there are approximately BT uncorrelated samples of its complex envelope. When BT is much less than unity, the channel is said to be under spread and the effects of the Doppler fading can be ignored, while, if greater than unity, it is overspread. Most of the described factors are caused by the chemical-physical properties of the water medium such as temperature, salinity and density, and by their spatio-temporal variations. These variations, together with the wave guide nature of the channel, because the acoustic channel to be temporally and spatially variable. In particular, the horizontal channel is by far more rapidly varying than the vertical channel, in both deep and shallow water. CHAPTER 3: Network Architecture Underwater sensor nodes: The underwater sensor nodes are deployed on the sea floor anchored to the ocean bottom [32]. The sensors are equipped with floating buoys to push the nodes upwards, thus they are relatively stationary nodes [3]. Using acoustic links, they relay data to underwater sink directly or via multi-hop path. Underwater sink nodes: Underwater sink nodes take charge of collecting data of underwater sensors deployed on the ocean bottom and then send to the surface sink node. They may be equipped with vertical and horizontal acoustic transducers. The horizontal transceiver is used to collect the sensors data and the vertical transceiver provides transmitting link between underwater sink and the surface sink node. Surface sink node: Surface sink node is attached on a floating buoy with satellite, radio frequency (RF) or cell phone technology to transmit data to shore in real time. 2D Model A reference architecture for two-dimensional underwater networks is shown in Figure. 1. A group of sensor nodes are anchored to the deep of the ocean. Underwater sensor nodes are interconnected to one or more underwater gateways by means of wireless acoustic links. Underwater-gateways are network devices in charge of relaying data from the ocean bottom network to a surface station. To achieve this objective, they are equipped with two acoustic transceivers, namely a vertical and a horizontal transceiver. The horizontal transceiver is used by the underwater-gateway to communicate with the sensor nodes in order to: send commands and configuration data to the sensors (underwater -gateway to sensors); collect monitored data (sensors to underwater -gateway). The vertical link is used by the underwater -gateways to relay data to a surface station. In deep water applications, vertical transceivers must be long range transceivers. The surface station is equipped with an acoustic transceiver that is able to handle multiple parallel communications with the deployed underwater -gateways. It is also endowed with a long range RF and/or satellite transmitter to communicate with the onshore sink (os-sink) and/or to a surface sink (s-sink). In shallow water, bottom-deployed sensors/modems may directly communicate with the surface buoy, with no specialized bottom node (underwater -gateway). 3D Model Three-dimensional underwater networks are used to detect and observe phenomena that cannot be adequately observed by means of ocean bottom sensor nodes, i.e., to perform cooperative sampling of the 3D ocean environment. In three-dimensional underwater networks, sensor nodes float at different depths to observe a phenomenon. In this architecture, given in Figure 2, each sensor is anchored to the ocean bottom and equipped with a floating buoy that can be inflated by a pump. The buoy pushes the sensor towards the ocean surface. The depth of the sensor can then be regulated by adjusting the length of the wire that connects the sensor to the anchor, by means of an electronically controlled engine that resides on the sensor. Sensing and communication coverage in a 3D environment are rigorously investigated in [8]. The diameter, minimum and maximum degree of the reachability graph that describes the network are derived as a function of the communication range, while different degrees of cov erage for the 3D environment are characterized as a function of the sensing range. 3D Model with AUV The above figure represents the third type of network architecture which consist of sensor nodes and Autonomous Underwater Vehicles (AUV) which act as mobile sensor nodes for ocean monitoring, underwater resource study, etc. CHAPTER 4: Differences between underwater and terrestrial Sensor Network An underwater acoustic channel is different from a ground-based radio channel from many aspects, including: Bandwidth is extremely limited. The attenuation of acoustic signal increases with frequency and range [6] [10]. Consequently, the feasible band is extremely small. For example, a short range system operating over several tens of meters may have available bandwidth of a hundred kHz; a medium-range system operating over several kilometers has a bandwidth on the order of ten kHz; and a long-range system operating over several tens of kilometers is limited to only a few kHz of bandwidth [11]. Propagation delay is long. The transmission speed of acoustic signals in salty water is around 1500 meter/s [22], which is a difference of five orders of magnitude lower than the speed of electromagnetic wave in free space. Correspondently, propagation delay in an underwater channel becomes significant. This is one of the essential characteristics of underwater channels and has profound implications on localization and time synchronization. The channel impulse response is not only spatially varied but also temporarily varied. The channel characteristics vary with time and highly depend on the location of the transmitter and receiver. The fluctuation nature of the channel causes the received signals easily distorted. There are two types of propagation paths: macro-multipaths, which are the deterministic propagation paths; and micro-multipath, which is a random signal fluctuation. The macro-multipaths are caused by both reflection at the boundaries (bottom, surface and any object in the water) and bending. Inter- Symbol Interference (ISI) thus occurs. Compared with the spread of its ground-based counterpart, which is on the order of several symbol intervals, ISI spreading in an underwater acoustic channel is several tens or hundred of symbol intervals for moderate to high data rate in the horizontal channel. Micro-multipath fluctuations are mainly caused by surface wave, which contributes the most to the time variability of shallow water channel. In deep water, internal waves impact the single-path random fluctuations [12][13]. Probability of bit error is much higher and temporary loss of connectivity (shadow zone) sometimes occurs, due to the extreme characteristics of the channel. Cost. While terrestrial sensor nodes are expected to become increasingly inexpensive, underwater sensors are expensive devices. This is especially due to the more complex underwater transceivers and to the hardware protection needed in the extreme underwater environment. Also, because of the low economy of scale caused by a small relative number of suppliers, underwater sensors are characterized by high cost. Deployment. While terrestrial sensor networks are densely deployed, in underwater, the deployment is generally more sparse. Power. The power needed for acoustic underwater communications is higher than in terrestrial radio communications because of the different physical layer technology (acoustic vs. RF waves), the higher distances, and more complex signal processing techniques implemented at the receivers to compensate for the impairments of the channel. Memory. While terrestrial sensor nodes have very limited storage capacity, underwater-sensors may need to be able to do some data caching as the underwater channel may be intermittent. Spatial Correlation. While the readings from terrestrial sensors are often correlated, this is more unlikely to happen in underwater networks due to the higher distance among sensors. CHAPTER 5: Layered of UASN The underwater architecture network consists of five layers, application, transport, network, data link and physical layer as shown in the figure below. As typical underwater systems have limited processing capability, the protocol has been kept as simple as possible without significantly compromising performance. The underwater sensor network specifications currently do not include any recommendations for authentication and encryption. These may be easily implemented at the application layer or via a spreading scheme at the physical layer. Each layer is described by a SAPI. The SAPI is defined in terms of messages being passed to and from the layer. The clients (usually higher layers) of a layer invoke the layer via a request (REQ). The layer responds to each REQ by a response (RSP). Errors are reported via an ERR RSP with error codes. If the layer needs to send unsolicited messages to the client, it does so via a notification (NTF). A layer communicates logically with its peer layer via protocol data units (PDU). As the peer-to-peer communication is symmetric, a layer may send a REQ PDU to its peer layer at any time. It would optionally respond to such a PDU with a RSP PDU. This is logically depicted in Figure below It may be desirable in some cases, that non-neighboring layers communicate with each other to achieve cross-layer optimization. This may be implemented by allowing REQ and RSP PDUs between any two layers in the protocol stack. The underwater sensor network specifications define detailed message structures for all SAPI messages. These message structures include message identifiers, data formats to be used, parameters and their possible values Physical layer The physical layer provides framing, modulation and error correction capability (via FEC). It provides primitives for sending and receiving packets. It may also provide additional functionality such as parameter settings, parameter recommendation, carrier sensing, etc. At first underwater channel development was based on non-coherent frequency shift keying (FSK) modulation, since it relies on energy detection. Thus, it does not require phase tracking, which is a very difficult task mainly because of the Doppler-spread in the underwater acoustic channel. Although non-coherent modulation schemes are characterized by high power efficiency, their low bandwidth efficiency makes them unsuitable for high data rate multiuser networks. Hence, coherent modulation techniques have been developed for long-range, high-throughput systems. In the last years, fully coherent modulation techniques, such as phase shift keying (PSK) and quadrature amplitude modulation (QAM), have become practical due to the availability of powerful digital processing. Channel equalization techniques are exploited to leverage the effect of the inter-symbol interference (ISI), instead of trying to avoid or suppress it. Decision-feedback equalizers (DFEs) track the complex, relatively slowly varying channel response and thus provide high throughput when the channel is slowly varying. Conversely, when the channel varies faster, it is necessary to combine the DFE with a Phase Locked Loop (PLL) [9], which estimates and compensates for the phase offset in a rapid, stable manner. The use of decision feedback equalization and phase-locked loops is driven by the complexity and time variability of ocean channel impulse responses. Differential phase shift keying (DPSK) serves as an intermediate solution between incoherent and fully coherent systems in terms of bandwidth efficiency. DPSK encodes information relative to the previous symbol rather than to an arbitrary fixed reference in the signal phase and may be referred to as a partially coherent modulation. While this strategy substantially alleviates carrier phase-tracking requirements, the penalty is an increased error probability over PSK at an equivalent data rate. Another promising solution for underwater communications is the orthogonal frequency division multiplexing (OFDM) spread spectrum technique, which is particularly efficient when noise is spread over a large portion of the available bandwidth. OFDM is frequently referred to as multicarrier modulation because it transmits signals over multiple sub-carriers simultaneously. In particular, sub-carriers that experience higher SNR, are allotted with a higher number of bits, whereas less bits are allotted to sub-carriers experiencing attenuation, according to the concept of bit loading, which requires channel estimation. Since the symbol duration for each individual carrier increases, OFDM systems perform robustly in severe multi-path environments, and achieve a high spectral efficiency. Many of the techniques discussed above require underwater channel estimation, which can be achieved by means of probe packets [17]. An accurate estimate of the channel can be obtained with a high probing rate and/or with a large probe packet size, which however result in high overhead, and in the consequent drain of channel capacity and energy. Data link layer (MAC layer) The data link layer provides single hop data transmission capability; it will not be able to transmit a packet successfully if the destination node is not directly accessible from the source node. It may include some degree of reliability. It may also provide error detection capability (e.g. CRC check). In case of a shared medium, the data link layer must include the medium access control (MAC) sub-layer. Frequency division multiple access (FDMA) is not suitable for underwater sensor network due to the narrow bandwidth in underwater acoustic channels and the vulnerability of limited band systems to fading and multipath. Time division multiple access (TDMA) shows limited bandwidth efficiency because of the long time guards required in the underwater acoustic channel. In fact, long time guards must be designed to account for the large propagation delay and delay variance of the underwater channel in order to minimize packet collisions from adjacent time slots. Moreover, the variable delay makes it very challenging to realize a precise synchronization, with a common timing reference, which is required for TDMA. Carrier sense multiple access (CSMA) prevents collisions with the ongoing transmission at the transmitter side. To prevent collisions at the receiver side, however, it is necessary to add a guard time between transmissions dimensioned according to the maximum propagation delay in the network. This makes the protocol dramatically inefficient for underwater acoustic sensor network. The use of contention-based techniques that rely on handshaking mechanisms such as RTS/ CTS in shared medium access is impractical in underwater, for the following reasons: large delays in the propagation of RTS/CTS control packets lead to low throughput; due to the high propagation delay of underwater acoustic channels, when carrier sense is used, as in 802.11, it is more likely that the channel be sensed idle while a transmission is ongoing, since the signal may not have reached the receiver yet; the high variability of delay in handshaking packets makes it impractical to predict the start and finish time of the transmissions of other stations. Thus, collisions are highly likely to occur. Code division multiple access (CDMA) is quite robust to frequency selective fading caused by underwater multi-paths, since it distinguishes simultaneous signals transmitted by multiple devices by means of pseudo-noise codes that are used for spreading the user signal over the entire available band. CDMA allows reducing the number of packet retransmissions, which results in decreased battery consumption and increased network throughput. In conclusion, although the high delay spread which characterizes the horizontal link in underwater channels makes it difficult to maintain synchronization among the stations, especially when orthogonal code techniques are used [17], CDMA is a promising multiple access technique for underwater acoustic networks. This is particularly true in shallow water, where multi-paths and Doppler- spreading plays a key role in the communication performance. Network layer (Routing) The network layer is in charge of determining the path between a source (the sensor that samples a physical phenomenon) and a destination node (usually the surface station). In general, while many impairments of the underwater acoustic channel are adequately addressed at the physical and data link layers, some other characteristics, such as the extremely long propagation delays, are better addressed at the network layer. Basically, there are two methods of routing. The first one is virtual circuit routing and the second one is packet-switch routing. In virtual circuit routing, the networks use virtual circuits to decide on the path at the beginning of the network operation. Virtual-circuit-switch routing protocols can be a better choice for underwater acoustic networks. The reasons are: Underwater acoustic networks are typical asymmetric instead of symmetric. However, packet switched routing protocols are proposed for symmetric network architecture; Virtual-circuit-switch routing protocols work robust against link failure, which is critical in underwater environment; and Virtual-circuit-switch routing protocols have less signal overhead and low latency, which are needed for underwater acoustic channel environment. However, virtual-circuit-switch routing protocols usually lack of flexibility. In packet-switch routing, every node that is part of the transmission makes its own routing decision, i.e., decides its next hop to relay the packet. Packet-switch routing can be further classified into Proactive routing, Reactive and geographical routing protocols. Most routing protocols for ground-based wireless networks are packet-switch based. Proactive routing protocols attempt to minimize the message latency by maintaining up-to-date routing information at all times from each node to any other node. It broadcasts control packets that contain routing table information. Typical protocols include Destination Sequence Distance Vector (DSDV) [28] and Temporally Ordered Routing Algorithm (TORA). However, proactive routing protocols provoke a large signaling overhead to establish routes for the first time and each time the network topology changes. It may not be a good fit in underwater environment due to the high probability of link failure and extremely limited bandwidth there. Reactive routing protocols only initiate a route discovery process upon request. Correspondently, each node does not need to maintain a sizable look-up table for routing. This kind of routing protocols is more suitable for dynamic environment like ad hoc wireless networks. Typical protocol examples are Ad hoc On-demand Distance Vector (AODV) [23], and Dynamic Source Routing (DSR) [27]. The shortage of reactive routing protocols is its high latency to establish routing. Similar to its proactive counterpart, flooding of control packets to establish paths is needed, which brings significant signal overhead. The high latency could become much deteriorated in underwater environment because of the much slower propagation speed of acoustic signal compared with the radio wave in the air. Geographic routing (also called georouting or position-based routing) is a routing principle that relies on geographic position information. It is mainly proposed for wireless networks and based on the idea that the source sends a message to the geographic location of the destination instead of using the network address. Geographic routing requires that each node can determine its own location and that the source is aware of the location of the destination. With this information a message can be routed to the destination without knowledge of the network topology or a prior route discovery. Transport layer A transport layer protocol is needed in underwater sensor network not only to achieve reliable collective transport of event features, but also to perform flow control and congestion control. The primary objective is to save scarce sensor resources and increase the network efficiency. A reliable transport protocol should guarantee that the applications be able to correctly identify event features estimated by the sensor network. Congestion control is needed to prevent the network from being congested by excessive data with respect to the network capacity, while flow control is needed to avoid that network devices with limited memory are overwhelmed by data transmissions. Most existing TCP implementations are unsuited for the underwater environment, since the flow control functionality is based on a window- based mechanism that relies on an accurate esteem of the round trip time (RTT), which is twice the end-to-end delay from source to destination. Rate-based transport protocols seem also unsuited for this challenging environment. They still rely on feedback control messages sent back by the destination to dynamically adapt the transmission rate, i.e., to decrease the transmission rate when packet loss is experienced or to increase it otherwise. The high delay and delay variance can thus cause instability in the feedback control. Furthermore, due to the unreliability of the acoustic channel, it is necessary to distinguish between packet losses due to the high bit error rate of the acoustic channel, from those caused by packets being dropped from the queues of sensor nodes due to network congestion. In terrestrial, assume that congestion is the only cause for packet loss and the solution lies on decreasing the transmission rate, but in underwater sensor network if the packet loss is due to bad channel then the transmission rate should not be decreased to preserve throughput efficiency. Transport layer functionalities can be tightly integrated with data link layer functionalities in a cross-layer module. The purpose of such an integrated module is to make the information about the condition of the variable underwater channel available also at the transport layer. In fact, usually the state of the channel is known only at the physical and channel access sub-layers, while the design principle of layer separation makes this information transparent to the higher layers. This integration allows maximizing the