Discuss the role of vitamin K, vitamin D and calcium on bone health Essay

Discuss the role of vitamin K, vitamin D and calcium on drop health across the lifespan and review the shew that supplementation with vitamin D and calcium - Essay ExampleIn this carriage the strength and vitality of the bones are maintained. However, this process varies in significant manner during advanced age, which may have a negative impact on the strength of the bone and its ability to satisfactorily perform its essential functions. With the increase in life spans being experienced virtually the world and particularly in the developed world maintaining healthy bones has become more important, so that the ripened segments of population can continue their active phase of life, without risks of damage of fractures to bones impeding the quality of their lives. This has led to increasing interest in the interaction amongst nutrition and bone growth and development and the nutrients that are significant in prevention of deficiencies, with particular emphasis on optimising peak bone mass and reservation the risk for osteoporosis minimal (Prentice, et al, 2006).Bones are made up of hard living tissue, which are in the form of hard matrix consisting of calcium salts deposited around protein fibres. The protein fibres are made up of collagen and provide the bones with their strength and elasticity, while it is the mineral deposits that make the bones rigid. Bones may be divided into the outermost bone and the interior(a) bone. The outer bone layer is called the periostem and it makes up eighty percent of the mass of a bone and provides rigidity to the bone. The trabecular bone is the inner bone, the structure of which looks like a honeycomb, due to the spongy mesh-like bone that it consists of to provide strength to the bone. It makes up twenty percent of the mass of the bone. Within the cavity of the bone, bone marrow is found, which is responsible for the production of red blood cells. Bones are in different shape and length based on the functions that t hey perform in the skeletal system. osteoclasts and

Colonialism in 1880-1900 Essay Example | Topics and Well Written Essays - 750 words

Colonialism in 1880-1900 - Essay ExampleAccording to the study the end of the slave throw was an additional main controlling feature to struggleds colonialism. Even though the trade wind of humans was legislated against, many of the Africans and Arabs continued the practice, particularly inland, where the European influence was less concentrated. Those Europeans apply to eliminating this practice were compelled to stay at these internal places with the intention of taking direct as well as instant action. Obviously, slavery was a profitable trade and its elimination meant that substitute trade and business required to be started all over Africa. Therefore, colonialists as well came into the continent to discover different trading means, types of merchant vessels and additional resources. They were required to teach the neighboring societies regarding commercial growth with the intention of maximizing the productivity of the countries. During the colonial phase, the perception of particular indigenous people in the African continent attained broader recognition, even though non without debate. From this paper it is clear that the extremely diverse and abundant ethnic groups, which consisted of most contemporary, self-governing African states, had within them different individuals whose condition, civilizations and pastoralist or huntsman life wee usually marginalized and set separately from the leading political as well as fiscal structures of the country. From the last part of 20th nose candy, these people have increasingly wanted identification of their constitutional rights as separate indigenous people, within both nationwide and worldwide perspectives. Given the widespread and complex account of human immigration inside Africa, being the earliest people within a territory is not a required condition for recognition as an indigenous people. To a certain extent, indigenous uniqueness communicates more to a set of attributes and practices than priority of reaching. For instance, quite a lot of populations of fluid people occupy regions within which they arrived somewhat lately. Their declaration to indigenous standing is founded on their marginalization as nomadic people in regions and countries ruled by inactive farming people. Early African reaction to European invasion into Africa during the last part of 19th century was not standardized. A small offspring of groups that had experienced long-term combat or slave raiding provided a doubtful welcome to European cosmea within their constituencies in anticipation that there would be harmony. Other groups vigorously opposed the arrival of European political power. On the other hand, a number of people had no initial response towards colonialism. This was due to the fact that the early years colonialism had slight impact on the lives of several rural African people. These mountain transformed as the impact of colonialism became more extensive as well as deep during the mid of th e 20th century. By the last part of world War I, the majority of Africa had been successfully colonized. European colonialists had managed to control the attempts by Africans to defend against the organization of colonial regulation. The subsequent two decades were known as the inter war years by historians and was somewhat calm within colonial Africa.

HR Research Paper Example | Topics and Well Written Essays - 1500 words

HR - Research Paper ExampleThe lodges vision is to exit one of the leading diversified oil companies in the world, characterized by a highly motivated workforce, as well as, safe operations. The companys boot is to enhance profitability and safety in mining and supplying of hydrocarbon fuels and feedstock. The company as well focuses on contributing to development of the nation.One of the companys key goals is fulfilling the country aspired standards for quality assurance, as well as, environmental protection. Because of orbicular warming, there are set standards both locally and internationally, for environmental conservation. Because of the level of environmental degradation associated with mining companies, the company faces extremely high standards. Additionally, because of sensitivity of oil products, the products set standards are as well high. The company as well is pull to implementing a couplet of national policies meant to increase employment opportunities for the cit izens.One of the key external factors that affect the company is the political factor. Over the last a couple of decades, there have been a series of political unrest in a couple of Middle East countries. This has been a threat to the stability of the companys profitability. One of the key reasons behind this is the fact that the company serves a couple of countries in the Middle East.Another key factor is the economic factor. The world(a) economic cycles affect the companys profitability as well. For example, during the 2008 global financial crisis, the company registered a decline in profitability. On the other hand, when the global economy is doing well, the company registers increased profitability.Technological factor as well affect the company. For example, the company has taken advantage of the ever-changing technology to automate closely of its oil production operations. This has enhanced efficiency in

Obesity in Children Essay Example for Free

Obesity in Children EssayWhat p arnts allow their pip-squeakren to discharge can affect their bodies and their life. to the amplyest degree children dont interpret the effects of long term illnesses such as obesity, type 2 diabetes, heart condition and high blood pressure. Taxing unhealthful foods and beverages could prove an central strategy to overconsumption and potentially aid in weight loss and reduced rates of diabetes among children and adults. Junk food should be taxed because it result reduce obesity, type 2 diabetes, and health c ar costs. First of all, taxing junk food will lower obesity among Americans. The increase in both soda and pizza install that many Americans would still buy junk food regard slight of a price increase. Taxing of sugary beverages at a penny-per-ounce rate with the goal of decrease consumption of obesity caused in drinks. The junk food tax would fund obesity related health initiatives such as diabetes c are. Obesity has been acknowledged as a national problem, notion of taxing junk food doesnt seem so bad. Secondly, Americans need to take better control over what they eat and what they feed their children.We must take a stand against obesity, type 2 diabetes, high blood pressure and heart disease in children and young adults. Most fast foods contain process meats and considered unhealthy in children. Americans dont admit an ideal what they are eating in fast food restaurants. How the political relation determined what foods should be served in schools. A couple of school systems such as Texas and California had a great idea to remove soft drinks, pop, soda, power drinks and cola from the schools lunch rooms along with fast foods such as burgers, French fries, hot ogs and convenience stores, too fight the obesity epidemic among the linked States and children. Replace drinks with orange juice, and water. Replace fast foods with fresh fruits, vegetables, salads and exercise. Obesity in the join States has risen fr om 48 percent to 65 percent within the ending thirty years and so has health care which has sky racket. We need to be more proactive in saving our children by eating healthy foods in the home and school.Schools need to change the vending machines to reflect eating healthy will help the body to become healthier. The school environment, nutrition, organizational reward groups, school policies that take away things such as sweetened beverages, and replace them with water, juice, fruit, vegetables and less junk food. Availability of less healthful food and beverages in schools is worldwide. notwithstanding changes in improving school food environment, availability of high fat food such things as pizza and hamburgers remain high in United States schools.Canadian elementary schools seem to have fewer vending machines, but less healthful food and beverages are available to all grades as they are made available through outlets such as cafeteria, school stores. It is said that schools ma y influence students into eating unhealthy by the lunches they extend and the vending machines that are in schools. Lastly, fast foods are not good because they have no nutrition value, most children that consume fast foods on a daily staple fibre start to gain weight due to lack of exercise. Children watch more TV and play more video games than exercising.Less exercise in schools, have also been a major factor contributing to obesity in children. Fast foods make children tired, the more you eat the less energy you have. When you walk into a store whether its a large grocery store or a small convenience store the lack of fruits and vegetables are small. Most children and adults are unaware that they have high cholesterol and high blood pressure. Most children who suffer from obesity also have a high rate of asthma. It would be a good idea if governments would rate schools on lunches they are providing to students.The school should prohibit advertising of fast foods, sweets and pop , prohibit use of less healthful foods , provide advertising that deals with eating healthy and healthy foods such as fruits, vegetables, seek educational requirements for school food and include requirements for nutrition education. Include exercise in the diet each day that way children wont feel tried after eating lunch. They will burn off fast and their bodies will feel better and become better in the long run. We need our children to be healthy. We need to avoid sickness, obesity, type 2 diabetes, heart disease and high blood pressure.Americans need to limit the intake of fast foods and start looking at healthy choices for themselves and their children. Medical bills have sky racket. If we plan to keep our generation of children around we better start looking at better ways of eating and providing nutrient in our everyday diet. Most people have cars, less people walk, ride bikes, or exercise. We have become lazy when it comes to exercise and eating healthy. Look at your childre n and ask yourself, do I want my child to continue looking like this, obese, sick and unhealthy.

Renaissance Artemisa Gentileschi Essay Example for Free

Renaissance Artemisa Gentileschi EssayMy idol of the Renaissance period is the famous woman artist framed Artemisia Gentileschi. She was born(p) in Rome on July 8, 1593. Her father was a well-know Roman artist named Orazio Gentileschi and my mother was named Prudentia Monotone. She died when Artemisia was twelve. Most women artists in this post-Renaissance era were limited to portrait paintings and poses. She was the first woman to paint major historical and religious scenarios, such as her painting, Judith Beheading Holofernes, c. 1620.At an early age she experienced loss. Two of her brothers died during childhood and her mother died tour giving birth. Showing some artistic expertness, Artemisia received some early training from her father. After art academies rejected her, her father hired his friend, Agostino Tassi, to teach her. In 1612, she was sexually assaulted by him. The trial was s tear down long months. Artemisia was tortured with thumb screws in order to make he r tell the truth of her claims. He was ultimately convicted, except Artemisa had a tarnished reputation after. She had been publicly humiliated and was severely criticized then and in her life forward.Artemisias first painting was named, Susanna and the Elder, c 1610. She was seventeen when she painted it. Michelangelo had a major influence on her style. The painting depicts the biblical story of Susanna, a young wife who was sexually harassed by the elder of her community. She shows her as endangered and frightened, while the men are conspiring behind her. This painting was completed before the infraction, but it might be a depiction of the harassment from Tassi. The trauma of the rape impacted how she painted she often painted graphic depictions of people dealing with pain.In 1612, she came to Florence, Italy where her father arranged for her to marry a Florentine artist name Pietro Antonia di Vincenzo Stiattesi. They became official members of the Academie del Disegno (Academy of Design) in 1616, which was a prestigious honor for me, a woman. Her first child, Giovanni Battista was born in September of 1613. Her second son, Cristofano, was born in November of 1615. Her husband is showtime to prefer gambling over working. They are in much debt.In August of 1617, she gave birth to a daughter named Prudentia sometimes called Palmira. She continued to live with Pietro even though it was loveless. He left me 10 years later. She had a second daughter in October of 1618, but she died in June of 1619. It was a difficult time and unknown to Artemisia, they are even in more serious debt than I had originally thought. In 1621, she returned to her hometown in Rome as ordered by Cosmo II de Midici. She was speculate to return in order recover from an illness and her family problems. She also spent time in Venice from 1627 to 1630. She never returned to Florence.She went to Genoa for a short time with her father and painted, Jael and Sisera. whatever of her patrons while back in Rome were cardinals Francesco and Antoni Barberion, both wealthy and influential prelates. By 1630, she moves to the city of Naples. Charles I of England and the Duke of Modena also purchased her paintings. Naples was the wealthiest city in southern atomic number 63 at this time. She also worked in England for a while beginning in 1638 where her father had a position at the court of Charles I. She returned after her father expiration in 1639.As noted above, her most famous painting, Judith Beheading Holfernes, illustrated an event from the Old Testament Book of Judith. Holofernes, the Assyrian general, was preparing to destroy the land of Judah. Judith then goes to a maidservant, Abra, to the Holorenes camp. She poses as a deserter from the Hebrews. Judith seduces him with her beauty, gives him alcohol, and then severs his headAfter her death, her grave marker was lost during church renovations and the inscription on her headstone, rather than mentioning her artwork, remembered her sexual scandal instead. In time, Artemisia was often forgotten about in the Art world and her paintings were often wrongly attributed to her father or other artists. Centuries later, renewed interest in Artemisia open her story, properly attributed her work and finally restored her reputation as one of the worlds most principal(prenominal) female artists and a major artist of the Italian Baroque period.Gentileschi often chose historic and biblical subjects that featured a female protagonist Susanna, Bathsheba, Esther, Judith. Her style was heavily influenced by dramatic realism and marked incompatible light and dark of Michelangelo Merisi da Caravaggio (1573 1610). The first book devoted to her, Artemisia Gentileschi The Image of The Female Hero in Italian Baroque Art. by Mary D. Garrard, was issued in 1989 her first exhibition was held in Florence in 1991. A TV documentary, a play, and more recently, a film have advanced her visibility as an important artist.As noted above, Artemisai Gentileschi, was inspired to paint by her father and by famous artist Michelangelo Merisi da Caravaggio. Today she is regarded as one of the most state-of-the-art and expressionist painters of her generation. After moving back to Rome French artist, Pierre Dunostier le Neveu, made a drawing of her hand holding a paintbrush. She on with her father were one of many artists invited by King Charles I of England to decorate the ceilings of the Queens house in Greenwhich.I am inspired by her because she chose to stand up and compete against the men of that time. Woman of that era had such difficulties trying to gain recognition for their work. She is one of the first women who eventually overcame adversity. Her technical skill showed human emotion from a womans perspective which some say is a breakthrough in art. In the words of Mary D. Garrard, she has suffered a scholarly neglect that is almost unthinkable for an artist of her caliber.picSusanna and The Elders c 1610picJudith Slaying HolfernesCited Workhttp//www.artbible.info/art/biography/artemisia-gentileschihttp//www.artemisia-gentileschi.com/index.shtmlhttp//en.wikipedia.org/wiki/Artemisia_Gentileschihttp//www.themasterpiececards.com/famous-paintings-reviewed/bid/31786/Female-Artists-Artemisia-Gentileschi

I Have a Dream Speech Analysis Essay Example for Free

I Have a Dream Speech Analysis Essay big businessman had suffered the racial injustice of America at that time and was tired of the segregation. We can never be satisfied as long as our children are stripped of their self-hood and robbed of their dignity by signs stating For Whites Only. At this suggest in time, society was segregated to an extreme. Blacks and whites did non mix, the black people were forced to sit at the back of the bus while the white people had the exclusive right of the front. The two races could not drink from the same water fountains and attended segregated schools.There had been attempts to make a change in the past such as Rosa Parks, however no one was able to leave the same lasting impression that fagot did and make such a change in society as we now know it. One day right there in Alabama little black boys and black girls will be able to join hands with little white boys and white girls as sisters and brothers. queen regnant had a dream, a drea m of racial equality. King was not competitiveness for only his own rights, he was as well as fighting for the future of his children, so that they would not endure the cruel police brutality of the times.In the oral communication King states I have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character. This does not only show his dream for the future generations but also gives the speech personal identity by including his own children. Throughout the speech King uses a various amount of linguistic devices that help to give his speech the limited edge needed to keep his terminology in the minds of listeners for years to come. One of the main styles of public speaking King uses is repetition.Throughout the speech he unvarying repeats certain words and catch phrases such as I have a dream or Let freedom ring. These help to drill his words into the audience and create a l asting impression. This is a technique that is generally apply in speeches, especially those dealing with politics. Obama, another man making a big change in society also uses this technique with his catch phrase Yes we can, the use of repetition allows the speaker to get their words through to every(prenominal) listener whether they realize it or not.King also includes aspects of the American Culture in his speech. This not only draws the attention of the white Americans but also shows a connection between the blacks and the whites, they are all Americans and they all live on the same land. King says lines like when architects of our republic wrote the magnificent words of the Constitution and the resolving power of Independence, this line praises the American beliefs. King gives a strong point of connection between the blacks and whites and their belief in the Declaration of Independence.He does not put down feather the American government despite the segregation and hardships but instead compliments them in his speech. The use of American Culture can also tie into Kings pacifism. King was against war and violence and in his speech he states we must not allow our creative protest to degenerate into physical violence, this connects to why he never puts down the government. King shows that with kindness you get further than with violence as the changes that he made in the world are such(prenominal) more than a war would have done.Another strong point of Kings speaking is his inclusivity of the audience. He rarely states his goals in the form of I but instead use we. This technique draws the audience in and includes them in the mission King is presenting to them. with this faith, we will be able to work together, to pray together, to manage together, to go to jail together, to back up to freedom together, knowing that we will be free one day. Note how King never refers to any of the actions in singular form. He says we will work together, stand up to freedom together.King always includes the audience to keep their attention and make them feel a part of the speech and like he is speaking directly to them and asking them to join him so that together they can make a change. King also used many links to religion. By linking his speech to biblical references he was able to connect on a deeper level with the religious members of his audience. During this point in time many people were spiritual, including the black population who were very religious as it helped them through the hard times of segregation and the assault they were experiencing.King used quotes such as the glory of the Lord shall be revealed and all flesh shall see it together referring to the thought that the Lords power will change by reversal cruelty and both blacks and whites will witness it together creating a world free from segregation. Another strong technique that King uses is alliteration. symbolic shadow we stand today, signed the repetition of the sound s creates a dramatic sentence emphasizing the words using this sound. It draws the audiences ear to these sentences and because of the similar sounds allows the phrase to be remembered easier.This allows King to have powerful sentences within the speech which continue capturing the audiences attention and allow for a more memorable speech. King often uses this technique as many parts of the speech include alliteration. Overall, King left a lasting impression on those who have listened to the speech. He does this by using the many different literary techniques to capture his audience at all times and leave them thinking about the points he put forward. King include various techniques to make his message strong and clear and leave a lasting impression.

Price Elasticity in Air Travel

outlay catch in Air TravelIntroductionElasticity is set up as the flavour sth has creation able to stretch and return to its original size and shape. (Oxford advanced l receiveers dictionary 6th edition). In Physics walkover is defined as the property of a substance that enables it to channelise its length, volume, or shape in direct response to a force effecting such a change and to discover its original form upon the removal of the force. (dictionaryreference.com).Suppose that your employer allows you to work exceptional hours more(prenominal)(prenominal) after your contracted hours for extra pay at the end of the month, the amount of extra m one and only(a)y you leave behind earn at the end of the month exit depend on how much more extra hours you ar able to work. then(prenominal) how responsive you atomic number 18 to this offer gouge be seen as snap. on that pointfore I go out define elasticity as the footstep of degree of reactivity of any variable to extra stimulus.From my example above elasticity can be calculated asEm = percentage of extra money you earn/percentage of extra hours worked.The belief of elasticity can be utilise to measure the rate or the exact amount of any change. In economics elasticity is roled to measure the magnitude of reactivity of a variable to a change in its determinants (sloman) such as ( film and supply) of dears and values.For the purpose of this essay am going to be examining the concept of elasticity of beseech and supply in the transmitline manufacture.Types of ElasticityPrice or own terms Elasticity of bringIncome elasticity of expectCross elasticityPrice or own equipment casualty elasticity of indigenceIt is the measure of the degree of sensitivity or responsiveness of metre petitioned is to a change in charge of a product (Edgar.K. browing). Our assumption often is that all shoot bows start out negative tilts which mean the dismay the price the higher the quantity demanded scarce aroundtimes the degree of responsiveness vary from product to product. For example a reduction in the price of cig bettes expertness have only bring about a little plus in quantity demanded whereas a super merchandise reduction in the price of washing up liquid leave behind produce a big ontogeny in quantity demanded The law of demand and even Common sense tells us that when prices change, the quantities purchased will change too. However, by how much? Businesses need to have more precise knowledge than this they need to have a clear measure of how the quantity demanded will change as a result of a price change.Price elasticity is calculated as the percentage (or equalizeral or rate) of change in quantity demanded divided by the percentage (or proportional or rate) of change in its price.SymbolicallyPD=%Q/%pHere denotes elasticity and diagrammaticallyElasticity measure in percentage because it allows a clear comparison of changes in qualitatively revealable things which are measured in two varied units (sloman). It is the only sensible way of deciding how big a change in price or quantity, so their calls a unit free measurement. in general when the prices of good incr informalitys the quantity demanded decreases, olibanum either of the number will be negative which after division will end up in a negative result, due to this fact we always ignore the sign and just concentrate on the absolute value, ignoring the sign to tell us how elastic demand is.The larger the elasticity of demand, the more responsive the quantity demanded is of elasticity.Degrees of elasticityPerfectly elastic exceedingly elasticRelatively elasticRelatively inelasticHighly inelasticPerfectly inelasticElastic DemandElastic demand occurs when quantity demanded changes by bigger percentage than price.(Sloman) Here customer has lot of early(a) alternative. The value is always higher than 1, the change in quantity has a bigger effect on total consumer spending than in pric e. For example if at that place is a reduction in the price of a bottle of washing up liquid say from 1.00 to 50p people will buy more credibly to store up, in doing this they will end up spending more on the product than they will do on a normal day.An dead DemandElasticity in transmitline laborThe channeliseline industry is deeply force by the elasticity of demand, externalities, pursue ine whole tone, and monetary, fiscal, and federal policies. The elasticity of demand is based purely on current market conditions, thcustomers September 11th tragedy had a negative affect on the entire go bad industry. It impacted the fiscal and monetary policies, supply and demand, and it created staffing problems nationwide. The rate of wage inequality is improving due to legislation that has created a pay increase in participating cities targetwise the United States. The airline industry is viewed has macrocosm unstable because it is based on current market conditions, and the market i s always changing. purpose for travel, and available substitutes. Externalities continue to function the elasticity of demand. TheElasticity of DemandThe airline industry is an extremely unstable industry because it is highly dependant upon current market conditions. Events such as inflation, terrorist attacks, and the price of oil have greatly influenced the demand for airline tickets throughout the years. Competition consistently affects the price of airline tickets because it gives the customer separate options. Substitutes that are existence is travelling by train, car, or ward offing travel whenever possible. Customers have resorted to all named substitutes during turbulent times in our economy. The elasticity of demand is greatly affected by the customers purpose for travel. airway customers typically fly for caper or pleasure. With the wave of technology, a large percentage of business travel has been eliminated to conserve spending.ElasticityIn the airline industry, pr ice elasticity of demand is separated into two segments of consumers and is considered to be both elastic and inelastic. A good example of how elastic demand is related to the airline industry is in relation to travel for pleasure. Pleasure travellers will be affected by the amount of travel they do based on the demand increase or decrease, affected by prices that humble with high demand or prices that rise with low demand directly attributed to competition in this market (Gerardi Shapiro, 2007). Inversely, the business traveller would apply to an inelastic demand for this market. This has shown by demand increases or decreases, as well as the price distribution attributed, which has little effect on the buying king of the business person (Gerardi Shapiro, 2007). Furthermore, Voorhees and Coppett (1981) explain that elastic demands exist for the pleasure traveler due to demand increase rising while prices lower and vise versa. The business traveler experiences an inelastic deman d due to the quantity of serving demanded and quantity has not decreased as prices have risen. In other words, this travel is seen as a necessary business tool, not affected by price changes in the demand cut back.As we have seen, the airline industry is extremely price elastic. Small shifts in prices have dramatic effects on the consumer base. Externalities, such as noise ordinances, can cause negative effects, ride constituteupward and threatening loss in demand due to a price sensitive customer base. Since deregulation, competition in the economy have kept prices in the industry low and have caused airlines to force cuts in areas such as wages contributing to a growing concern of wage inequality.RefrencesGerardi, K., Shapiro, A. (2007, April). The Effects of Competition on Price Dispersion in the Airline Industry A Panel Analysis. Working Paper Series (Federal Reserve blaspheme of Boston), 7(7), 1-46. Retrieved April 30, 2008, from Business Source Complete entropybase.Mank iw, N. G. (2004). Principles of economics (3rd ed.). Chicago, IL Thomson South-Western.Morrison, S., Watson, T., Winston, C. (1998). Fundamental Flaws of Social Regulation The Case of Airplane Noise. Retrieved May 8, 2008, from http//www.brookings.edu//media/Files/rc/papers/1998/09_airplane_winston/09_airplane_winston.pdfVoorhees, R., Coppett, J. (1981, Summer). New Competition for the Airlines. transference Journal, 20(4), 78-85. Retrieved April 30, 2008, from Academic Search Premier database.The airline industry is a private good. Mankiw (2004), states that private goods are excludable and rival goods. One needs to see through the anti-trust laws and regulations that charm some to call the industry a natural monopoly airlines still reserve the right to administer price and destination. The airline industry shows that it is an excludable good by having the power to place prices on fares and having the ability to refuse service to any person for whatever the reason. The airline industry also shows that it is a rival good because when someone purchases fare for a seat, it diminishes the ability for another person to get a seat on the plane. Because the airline industry is a private good, in a competitive market place, prices, supply, and demand are very sensitive to new policies or tax incidences placed on them.Associated content.com viewd 18/11/10WordPress.comThis phenomenal increase in the demand for domestic air travel is not surprising. Airfare is an expensive commodity that few people can afford or are willing to pay for it. Also, a typical consumer may not be able to avail such commodity regularly. It takes time for the consumer to demand for it again.In economics, this scenario is being explained by its ELASTICITY. The concept of elasticity is being referred as the responsiveness of the quantity demanded of a good or service to a change in its price, income, or cross price. This post will provide a better understanding on this matter, specifically t he price elasticity.AnalysisBelow consists of indicators that determines the elasticity of a good/service. national air travel has been employed as a sample commodity.Substitutes. (The more substitutes it has, the higher the elasticity.) Airlines have numerous substitutes such as land or sea transportation.Percentage of Income. (The higher the percentage that the products price is of the consumers income, the higher the elasticity.) Airfares are too expensive relative to household income.Necessity. (Basic goods have lower elasticity.) Airline tickets are luxury goods.Duration. (The longer a price change holds, the higher the elasticity.) Airline fare does not change for a long time.Breadth of Definition. (The broader the definition, the lower the elasticity.) Domestic airline travel has more specific definition than ordinary air transportation.1. IntroductionThe purpose of this study is to report on all or to the highest degree of the economics and business literature dealing wit h observationally estimated demand functions for air travel and to collect a range of fare elasticity measures for air travel and provide some judgment as to which elasticity values would be more representative of the true values to be found in different markets in Canada.While existing studies may include the leisure business class split, other important market distinctions are often omitted, likely as a result of data availability and quality.3 One of the principal value added features of this research and what distinguishes it from other surveys, is that we develop a meta-analysis that not only provides measures of dispersion but also take ins the quality of demand estimates based on a number of selected study characteristics. In particular, we develop a means of scoring features of the studies such as focus on length of haul business versus leisure international versus domestic the inclusion of income and inter-modal effects the age of the study data type (time-series versus cross section) and the statistical quality of estimates (adjusted R-squared values). By scoring the studies in this way, policy makers are provided with a sharper focus to aid in judging the relevance of non-homogeneous estimated elasticity values.42. Elasticity in the Context of Air Travel Demand.Elasticity values in economic analysis provide a units free measure of the sensitivity of one variable to another, given some pre-specified functional relationship. The most commonly utilized elasticity concept is that of own-price elasticity of demand. In economics, consumer choice speculation starts with axioms of preferences over goods that translate into expediency values. These utility functions define choices that generate demand functions from which price elasticity values can be derived.Own-price elasticity of demand concept airtrav_2e.gif (1,979 bytes)Therefore elasticities are summary measures of peoples preferences reflecting sensitivity to relative price levels and changes in a resource-constrained environment. The ordinary or Marshallian demand function is derived from consumers who are postulated to maximize utility subject to a budget constraint. As a goods price changes, the consumers real income (which can be used to consume all goods in the choice set) changes. In addition the goods price relative to other goods changes. The changes in consumption brought about by these effects following a price change are called income and central effects respectively. Thus, elasticity values derived from the ordinary demand function include both income and substitution effects.5Own-price elasticity of demand measures the percentage change in the quantity demanded of a good (or service) resulting from a given percentage change in the goods own-price, holding all other independent variables (income, prices of related goods etc.) fixed. The ratio of percentage changes thus allows for comparisons mingled with the price sensitivity of demand for products that mi ght be measured in different units (natural gas and electricity for example). Arc price elasticity of demand calculates the ratio of percentage change in quantity demanded to percentage change in price using two observations on price and quantity demanded. formally this can be expressed asEquation(1)whereEquationrepresent the observed change in quantity demanded and priceEquationrepresent the average price and quantity demanded. The elasticity is unitless and can be interpreted as an index of demand sensitivity it is measuring the degree to which a variable of interest will change (passenger traffic in our case) as some policy or strategic variable changes (total fare including any added fees or taxes in our case).In the limit (when Equationare very small) we obtain the point own-price elasticity of demand expressed asEquation(2)whereQ(P,S) is the demand functionP = a vector of all relevant pricesp = the goods own-price.q = equals the quantity demanded of the goodS = a vector of all relevant shift variables other than prices (real income, demographic characteristics etc.)We expect own-price demand elasticity values to be negative, given the inverse relationship between price and quantity demanded implied by the law of demand, with absolute values less than unity indicating inelastic demand a less than proportionate response to price changes (relative price insensitivity). Similarly, absolute values exceeding unity indicate elastic or more sensitive demand a more than proportionate demand response to price changes (relative price sensitivity).The ratio of change in quantity demanded to change in price equation (1) highlights that elasticity measures involve linear approximations of the slope of a demand function. However, since elasticity is measuring proportionate change, elasticity values will change along almost all demand functions, including linear demand curves.6 musical theme of elasticity values is therefore most useful for predicting demand responses in the vicinity of the observed price changes. As a related issue, analysts need to recognize that in markets where price discrimination is possible aggregate data will not allow for accurate predictions of demand responses in the relevant market segments. In air travel, careers by a carrier are essentially joint products consisting of differentiated service bundles that are identified by fare classes. However the endure management systems employed by full-service carriers (FSCs) also create a complex form of inter-temporal price discrimination, in which some fares (typically economy class) decline and some increase (typically full-fare business class) as the departure date draws closer. This implies that ideally, empirical studies of air travel demand should separate business and leisure travellers or at least be able to include some information on booking times in order to account for this price discrimination, and that price data should be gradatory for inter-temporal price di scrimination for example, the use of full-fare economy class ticket prices as data will overestimate the absolute value of the price elasticity coefficient. indoors the set of differentiated service bundles that comprise each (joint product) flight, the relative prices are important in explaining the relative ease of substitution between service classes. habituated the nature of inter-temporal price discrimination for flights, the relative price could also change significantly in the time period prior to a departure time.The uncomplete derivative in (2) indicates that elasticity measures price sensitivity independent of all the other variables in the demand function. However when estimating demand systems over time, one can expect that some important shift variables will not be constant. It is important that these shift variables be explicitly recognized and incorporated into the analysis, as they will affect the value of elasticity estimates. This will also be true with some cro ss-sectional studies or panels.7 In particular changes in real income and the prices of substitutes or complements will affect demand. In air travel demand estimations, income and prices of other relevant goods should be include in the estimation equation. Alternative transportation modes (road and rail) are important variables for short-haul flights, while income effects should be measured for both short and long-haul. The absence of an income coefficient in empirical demand studies will result in own-price elasticity estimates that can be slashed. With no income coefficient, observed price and quantity pairs will not distinguish between movements along the demand curve and shifts of the demand curve.8The slope of a demand function, which affects the own-price elasticity of demand, is generally expected to decrease (become shallower) withThe number of available substitutesThe degree of competition in the market or industryThe ease with which consumers can search and compare prices The homogeneity of the productThe duration of the time period analyzed.9Given the implied relationships above, any empirical demand study should carefully define market boundaries to include all relevant substitutes and complements and to exclude products that might be related through income or other more general variables.In air travel, ideally market segment boundaries should be defined by first separating leisure and business passengers and second long-haul and short-haul flights. The reason is that we expect different behaviour in each of these markets. Within each of these categories, distinctions should then be made between the followingConnecting and origin-destination (O-D) travelHub and non-hub airports10Routes with dominant airlines and routes with low-cost carrier competition.In addition, for the North American context, long-haul flights should be further divided into international and domestic travel (within continental North America). These market segment boundaries are illustrated in figure 2.1 below, which also highlights the relative importance of intermodal competition for short-haul travel.While distinctions in price and income sensitivity of demand between business and leisure or long and short-haul travel are more intuitive, other distinctions are perhaps less obvious. If available, data that distinguishes between routes, airlines and airports would provide important estimates of how price sensitivity is related to the number of competing flights and the willingness to pay of passengers utilizing a hub-and-spoke system network, relative to those traveling point-to-point, more commonly associated with low cost carriers. To the extent that existing studies assume that each passenger observation represents O-D travel, they will not be capturing fare premiums usually associated with hub-and-spoke networks and full service carriers, nor will they necessarily capture the complete itinerary of travellers utilizing a number of point-to-point fligh ts with a low cost carrier. For example, a passenger who travels from Moncton to Vancouver with Air Canada, and utilizes the hub at Pearson International airport, is being provided with a number of services that includes baggage checked through to the final destination and ordinary flyer points as well as a choice in flights and added flight and ground amenities. The fare for Moncton-Vancouver includes a premium for these services. Now consider a passenger that is travelling with WestJet from Moncton to Hamilton, and then with JetsGo from Toronto Pearson Airport to Vancouver. In this case there are no frequent flyer points to be attained and baggage has to be collected and re-checked after a road transfer between Hamilton and Pearson International. Although the origin and destination is the same for these passengers, the itineraries are significantly different. In many cases data used for demand estimates would not able to account for these differences.Route-specific data can also capture competition that may exist between airports and the services they offer as well as airlines. This may be especially true for received short-haul routes where intermodal competition (road and rail) can play an important role in shaping air travel demand.3. Measurement IssuesOum et al. (1992) provide a valuable list of pitfalls that occur when demand models are estimated and therefore affect the interpretation of the elasticity estimates from these empirical studies.1. Price and Service Attributes of Substitutes Air travel demand can be affected by changes in the prices and service quality of other modes. For short-haul routes (markets) the relative price and service attributes of auto and train would need to be included in any model particularly for short-haul markets. Failure to include the price and service attributes of substitutes will bias the elasticity. For example, if airfares increase and auto costs are also increasing, the airfare elasticity would be overestimated if auto costs were excluded.2. Functional Forms Most studies of air travel demand use a linear or log-linear functional specification. Elasticity estimates can vary widely depending on the functional form. The choice of functional form should be selected on the basis of statistical testing not ease of interpretation.3. Cross-Section vs. Time-series Information In the long run demand elasticities for non-durable goods and services are larger in absolute terms, than in the short run. This follows because in the long run there are many more substitution possibilities that can be used to avoid price increases or service quality decreases. In effect there are more opportunities to avoid these changes with substitution possibilities. Data tends to be cross-sectional or time-series although more recently panels have become available. A panel is a combination of cross-section and time-series information on several routes for a multi-year period is a panel. Cross-sectional information is ge nerally regarded as indicating short run elasticities while time-series data is interpreted as long run elasticities. In time-series data the information reflects changes in markets, growth in income, changes in competitive circumstances, for example. Policy changes should rely on long run elasticities since these are long run impacts that are being modelled. Short run elasticities become important when considering the competitive position of firms in a highly dynamic and competitive industry.4. Market Aggregation/Segmentation As the level of aggregation increases the amount of variation in the elasticity estimates decreases. This occurs because aggregation averages out some of the underlying variation relating to specific contexts. Since air travel market segments may differ significantly in character, competition and dominance of trip purpose, interpreting a reduction in variation through aggregation as a good thing would be erroneous. Such estimates might have comparatively low s tandard deviations but would be also be relatively inaccurate when used to assess the effect of changes in fares in a specific market.5. Identification Problem In most cases only demand functions are estimated in attempts to measure the demand elasticity of interest. However, it is well known that the demand function is part of a simultaneous equations system consisting of both supply and demand functions. Therefore, a straightforward estimation of only the demand equation will produce biased and inconsistent estimates. The problem of identification can be illustrated by describing the process by which fares and travel, for example, are determined in the origin-destination market simultaneously. To model this process in its entirety, we must develop a quantitative estimate of both the demand and supply functions in a system. If, in the past, the supply curve has been shifting due to changes in production and cost conditions for example, while the demand curve has remained fixed, the resultant intersection points will trace out the demand function. On the contrary, if the demand curve has shifted due to changes in personal income, while the supply curve has remained the same, the intersection points will trace out the supply curve. The most likely outcome, however, is movement of both curves yielding a pattern of fare, quantity intersection points from which it will be difficult, without further information, to distinguish the demand curve from the supply curve or estimate the parameters of either.11Earlier we identified sources of bias that can arise from problems with aggregation, data quality, implicit assumptions of strong separability among others. Almost all demand studies have an implied assumption of strong separability in that they only consider aviation markets in the analysis. Such studies in effect constrain all changes or responses in fares or service to be wholly contained in the aviation component of peoples consumption bundle. The paper by Oum a nd Gillen (1986) is the one exception where consideration of substitution with other parts of consumption was included in the modelling. It would be difficult to extract a conclusion from this one study as to existence, degree and direction of bias in elasticity estimates when other parts of consumption are and are not included in the modelling. However, having said this, an inspection of the elasticity estimates from this study shows they are not significantly different than other time-series estimates.3.1 Data IssuesElasticity estimates depend critically on the quality and extent of the data available. Currently, the best data for demand estimation is the DB1A 10 percent ticket sample in the US, but even this data has some problems.12 The DB1A sample represents 10 percent of all tickets sold with full itinerary identified by the coupons attached to the ticket. However with electronic tickets, as more and more tickets are being sold over the Internet, there is a growing portion of overall travel that may not be captured in the sample. This means that the proportion is not 10 percent but something less.13 Other important considerations are the amount of travel on frequent flyer points, by crowd and airline personnel.In Canada we have poor quality data because it is incomplete, even if it were accessible. Airports collect traffic statistics but these data make it very difficult to distinguish OD and segment data. Airlines report traffic data to Statistics Canada (or are supposed to) but these data do not include fare information or routing. Knowing the itinerary or routing is important because of differences in service quality and hubbing effects. Fare data is also more useful than yield information since it identifies the proportion of people travelling in different fare classes. Yet, in many cases yield information is used as a weighted average fare. There is also the problem that carriers of different size may have different reporting requirements. Some res earchers and consultants have been cobbling together data sets for analysis by using the PBX clearing house information. These data are limited and apply only to those airlines that are members of IATA.14 The current public data available in Canada only does not permit estimation of any demand models.Besides demand side data it is also important to have supply side information. Elasticity estimates should emerge from a simultaneous equations framework. This data is more accessible through organizations like the OAG15, which provide information on capacity, airline and aircraft type for each flight in each market.16 These data measure changes in capacity, flight frequency and timing of flights.One study, which undertook an extensive survey to collect multimodal data,17 was the High Speed condition study sponsored jointly by the Federal, Ontario and Quebec governments. This study, which had three different demand modelling efforts, examined the potential for High Speed Rail demand, and subsequent investment, in the Windsor-Quebec corridor. The analysis included intermodal substitution between air, rail, bus and car. The study was undertaken in the early 1980s. However, it is not possible for public access to any of the technical documents that would allow an assessment of the study. Attempts in the past to obtain access to the data have proven fruitless.3.2 Distinguishing Elasticity MeasuresAs we have stated, price elasticity measures the degree of responsiveness to a change in own or other prices (fares). However, care must be exercised in interpreting the elasticity since they differ according to how they have been estimated. Many empirical studies of air travel demand estimate a log-linear model. In evaluating such studies, it is important to keep in mind that the empirical specification implies a certain consumer preference structure because of the duality between utility functions and demand functions. It is equally important to remember that empirically estimated demand functions should contain some measures of quality and service differences or quality changes over time. Failure to include metrics for frequent flyer programs, flight frequency, destination choice or service levels in estimating an air demand function can lead to downward bias in the price elasticity estimates.Price elasticities can be estimated for aggregate travel demand as well as modal demand. Figure 3.1 illustrates the differences between aggregate and modal elasticities.18 Our interest is in modal elasticities not the aggregate amo