Fuel cells Essay Example | Topics and Well Written Essays - 1000 words

Fuel cells - Essay Example This is then used to run a turbine to produce electricity. Thus there are many intermediate steps each with certain efficiency (always less than 100%) associated with each of them. This is because thermal energy is the worst form of energy with maximum entropy and therefore can never be converted fully into useful work. Now the overall efficiency of chemical potential energy to electricity conversion is a product of efficiency of each of the intermediate steps and therefore is much smaller. The best thermal power plants operate at maximum conversion efficiency of about 40%. Also, the combustion products are highly polluting adding to carbon emission and global warming. Fuel cells on the other hand convert the chemical potential energy directly into electricity and thus have very high conversion efficiency which is typically 70%. Besides, the reaction products are relatively harmless and in many cases completely harmless. Thus fuel cells are being seen as power plants of future and a tangible potential solution for containing the menace of carbon emission and therefore, global warming. These are already into many specialized and high end applications. In this report the basic principle, related developments and current and potential applications of fuel cells are briefly discussed. A fuel cell is like a galvanic cell. It directly converts chemical energy into electricity and is highly efficient. It is now possible to make such cells in which reactants are fed continuously to the electrodes and products are removed continuously from the electrolyte compartment. Galvanic cells that are designed to convert the energy of combustion of fuels like hydrogen, methane, methanol, etc. directly into electrical energy are called fuel cells. Such a fuel cell was used for providing electrical power in the Apollo space program. The water vapors produced during the reaction were

Human Developmental Theories Essay Example | Topics and Well Written Essays - 500 words

Human Developmental Theories - Essay Example Psychological researchers have greatly investigated all the attributed of human life that lead to nurture and development of human psychology. As a result, various theories have been originated such as reductionism, meditational, determinism, contextualism etc. Psychologists have divided such theories into certain categories (Barkway 2009, p. 21). Determinism is a theoretical approach for psychologists to evaluate human psychology which is resolute over the time in connection to the past experiences. Psychologists evaluate human psychology by viewing the past history of child. Sigmund Freud suggested that there are certain patterns that could be studied while implementing the theory of determinism (Barkway 2009, p. 21). Such aspects include parental history because it greatly affects a child’s development in the period of adolescence. Parent history has a lot in relation with the child development as parents tend to be responsible of child nurture process in every society. Secondly, the history of behaviour could be a very important aspect in understanding human psychological development (Barkway 2009, p. 22). Medical implication of deterministic theory on health care practice is the most effective way to help patients. Deterministic theory can be applied on children as it studies the events that took place in the life of a child. Certain questions could be easily answered with the implication of deterministic approach for health care practice.

Pro Genetically Modified Foods Essay Example for Free

Pro Genetically Modified Foods Essay We must have science to make medicine. All of us have been to the doctor to get medicine at least once in their lives. Think about how many people would die each year if it weren’t for modern day medicine; a lot, right? So it’s safe to say that some of us trust in medicine but not the science of genetically modifying foods? Believe it or not, genetically modifying foods has been around for thousands of years. â€Å"About 8,000 years ago, for example, farmers in Central America crossed two mutant strains of a weedy-looking plant called Balsas teosinte and produced the first corn on the cob. † (http://www. pbs. org/wgbh/harvest/engineer/) Without GM foods, farmers would be using more pesticides to keep their crops fresh. Scientists have created pest resistant plants that require fewer pesticides and grow faster. Along with being more cost efficient for farmers, the farmer’s use of fewer pesticides has been thought to be safer for consumers and for the environment. â€Å"How is the environment affected by pesticides? † After the rain comes and washes all the pesticides on the crops away the chemicals run off into the ground water and the water becomes contaminated. Then the animals of the surrounding area consume the water and then become sick and eventually die. If corn were not genetically modified, many crops would die as a result of pests and poor resiliency to changes in the weather. One of the biggest pathogens for corn is said to be the European corn borer. Because this insect subsides inside of the corn husk, pesticides do little to fix the issue. As a result of reduced production of corn, produce prices would become inflated and many people could no longer afford to buy it.

Exogenous IL-10 and Golimumab for Heart Failure Treatment

Exogenous IL-10 and Golimumab for Heart Failure Treatment Synergistic Effect of Exogenous IL-10 and Golimumab in the Treatment for Heart Failure in Rats Running title: Heart Failure Treatment Highlights: The level of TNF-ÃŽ ± decreased after treatment with IL-10 and golimumab. The level of IL-10 was increased by IL-10 combined with golimumab. IL-10 and golimumab have a synergistic effect on HF in rats. ABSTRACT Objectives We attempted to assess the therapeutic effect of exogenous interleukin-10 (IL-10) in combination with golimumab in treating heart failure (HF) in rats, and provide an experimental basis for clinical application. Methods HF animal model was induced in Sprague-Dawley (SD) rats by intraperitoneally injection with adriamycin, and rats in control group were treated with 0.9% normal saline. The HF rats were randomly divided into 4 groups: group A (HF group, n = 10), group B (IL-10 group, n = 10), group C (golimumab group, n = 10), and group D (IL-10 and golimumab group, n = 10). The normal rats were defined as controls in group E (n=10). Three months later, myocardial functional indexes and hemodynamic indexes of rats in all groups were measured. The levels of TNF-ÃŽ ± and IL-10 in serum were detected by enzyme linked immunosorbent assay (ELISA). Results The HF rat model was successfully constructed. After the treatment, compared with group A, the hemodynamic indexes in groups B-D were distinctly different (P P P P Conclusions IL-10 and golimumab has synergistic effect in the treatment of HF in rats, suggesting a potential clinical application of IL-10 combined with golimumab. Key words: cytokines; golimumab; heart failure; IL-10; TNF-ÃŽ ± INTRODUCTION Heart failure (HF) is considered to be a condition in which the heart can hardly pump sufficient blood to meet the need of the body [1]. It was demonstrated that HF is closely related to several diseases such as hypertension, ischemic heart disease, diabetes, obesity and dyslipidaemia [2]. HF has already been a major cause of morbidity and mortality worldwide [3, 4]. It was reported that more than23 million people in the world are suffering from HF [1]. Mortality caused by HF is up to 30%-40% within one year, and rise to a rate of 50%-75% within 5 years [5, 6]. So, HF has been a health concern all over the world. Previous studies suggested that the imbalance of anti-inflammatory and pro-inflammatory cytokines played a key role in the progression of HF [7]. Recent studies have highlighted the effects of some cytokines on immune-mediated myocyte injury, postischemic myocardial inflammation, and heart function. Levels of anti-inflammatory cytokines such as interleukin-10 (IL-10) are reduced in HF development [8-11]. Evidences demonstrated IL-10 controlled inflammation by inhibiting pro-inflammatory cytokine synthesis and inducted antiapoptotic processes [12]. IL-10 can promote healing of ventricular damage to avoid ventricular remodeling [13, 14]. IL-10 can enhance humoral immunity by inhibiting cell-mediated immunity to resist HF. Thus, IL-10 is considered to be a candidate for the management of HF, [12]. Serum level of pro-inflammatory cytokines of tumor necrosis factor ÃŽ ± (TNF-ÃŽ ±) are found to be elevated in experimental models of HF [15]. Studies declared that an increase of TNF-ÃŽ ± con centration resulted in necrosis and apoptosis of myocardial cells, finally led to ventricular remodeling by the progressive thinning and expansion of ventricular wall [16]. TNF-ÃŽ ± was reported to lower the myocardial systolic function directly [13, 14]. Furthermore, evidences uncovered the relationship of TNF-ÃŽ ± and progression of HF: elevated level of TNF-ÃŽ ± contributed to the development and progression of HF by activation of matrix metalloproteinases, and promotion of myocardial hypertrophy and contractile dysfunction [12]. Therefore, the TNF-ÃŽ ± inhibitors, as medicines for HF treatment, had been becoming the current hot topics in HF studies. Nowadays, etanercept, a recombinational TNF-ÃŽ ± inhibitor, had been synthesized already, which inhibit the pro-inflammatory of TNF-ÃŽ ± due to the interdicted effect for the conjugation of TNF-ÃŽ ± and cell membrane receptor [17]. Golimumab, another TNF-ÃŽ ± inhibitor, is a monoclonal antibody specific for human TNF-ÃŽ ± [18]. It can inhibit the bioactivity of TNF-ÃŽ ± via binding to TNF-ÃŽ ± with high affinity and specificity to prevent TNF-ÃŽ ± from combination with TNF receptor [19]. In addition, IL-10 has been shown to play a pivotal role in the mucosal immune system by inhibition of pro-inflammatory cytokine synthesis such as TNF-ÃŽ ± [20, 21]. However, there are few studies reporting the effect of exogenous IL-10 combined with golimumab forthe HF treatment. In the present study, we used HF rats model, which was induced by intraperitoneal injection with adriamycin (ADR), to explore the effect of exogenous IL-10 combined with golimumab in the treatment for HF. To analyze the therapeutic effects, IL-10 or/and golimumab were intraperitoneally injected into the HF rats and the effects of the treatments were tested by measuring heart functional indexes and level of inflammatory cytokines. In addition, the possible mechanisms of this effect were investigated. MATERIALS AND METHODS Rats model of heart failure Fifty 10-week-old Sprague-Dawley (SD) rats, including 25 females and 25 males, were provided by Laboratory animal center, southern medical university Southern Medical University. Forty rats, with 20 females and 20 males, were chosen at random. Rats with HF were induced by intraperitoneal injection with 4 mg/kg adriamycin (ADR) once a week for 6 times. Control rats were given the same volume of normal saline. Experimental design and drug administration After 6 weeks, the model rats were randomly divided into 4 experimental groups: HF group (group A, n=10), IL-10 group (group B, n=10), golimumab group (group C, n=10), and IL-10 and golimumab group (group D, n=10), with 5 females and 5 males in each group. The normal rats were considered as controls in group E (n=10). Rats in group B was given an intraperitoneally injection of 50 pg/kg IL-10 each week. Exactly, 1 mg/kg golimumab (Centocor Ortho Biotech Inc) was administered intraperitoneally into the rats in group C each month. Rats in group D was intraperitoneally injected with 50 pg/kg IL-10 each week and 1 mg/kg golimumab each month. At the same time, rats in groups A and E received an intraperitoneal injection of 1ml normal saline. Rats in each group were treated for 3 times in total. During the test period, rats were fed on food and clean water freely. Echocardiography Three months after administration, echocardiographic indicators were obtained using a color doppler ultrasonic cardiograph (Vingmed CFM-725). Rats were anaesthetized with 5 ml/kg urethane solution at a concentration of 20% by intraperitoneal injection, and left ventricular long-axis and M-mode curve at the level of the left papillary muscles were measured. Finally, the left ventricle end-diastolic diameter (LVEDD), the left ventricle end-systolic diameter (LVESD), left ventricular posterior wall depth (LVPWD) were measured, and the left ventricle fractional shortening (LVFS) can be calculated by the factors above, the formula is as follows: à £Ã¢â€š ¬Ã¢â€š ¬LVFS = [( LVEDDà ¯Ã‚ ¼Ã‚ LVESD)/LVEDD]Ãâ€"100%. Measurements of haemodynamic parameters After anaesthetization, rats were fixed followed bytracheal intubationwith artificial ventilation. Super-miniature cardiac catheter was connected to multipurposepolygraph (Nikon 4) through the right common carotid artery and ascending aorta. Systolic pressure (ASP), diastolic pressure (ADP) and heart rate (HR) was recorded. As a follow-up, the cardiac catheter were inserted into the left ventricle, the left ventricle systolic pressure (LVSP), the left ventricular end-diastolic pressure (LVEDP) and the maximum rate of the left ventricular pressure rise (+dp/dtmax) and decline (-dp/dtmax) were measured. Then, allratsweresacrificed to weight the body. Their hearts were weighted after washing by cold normal saline and drying by filter paper. Finally, Heart weight/Body weight (HW/BW, mg/g) was calculated based on HW and BW. Determination of the level of TNF-ÃŽ ± and IL-10 in serum After hemodynamic evaluation, 2 ml blood samples were drawn from the catheter positioned in the left common carotid artery, and collected into a 2 ml tube. After 30 min, the blood samples were centrifuged at 3000 r/min for 10 min. The supernatant were collected into Eppendorf (EP) tube. The concentration of TNF-ÃŽ ± and IL-10 in serum were detected by using an ELISA kit (RayBiotech. Inc), and experimental procedures were conducted according to themanufacturer’sinstructions stringently. Statistical analysis The data were represented as mean  ± standard deviation (SD). Comparisons between groups were analyzed by one-way ANOVA and q-test (Student-Newman-Kueulsmethod). All statistical analyses were performed by using SPSS 12.0 software (SPSS, Chicago, IL). P RESULTS Heart function When the model establishment was completed, all of the rats suffered from HF, showing symptoms including dyspnea, edema, feed difficulty and oliguria. HF symptoms of the rats in groups B-D were alleviated after the treatment with IL-10, golimumab, and IL-10 and golimumab respectively. Obviously, symptoms of the rats in group D were most significantly alleviated. There was no rat died during the experimentation. Changes of BW, HW and HW/BW in the rats after treatment As shown in table 1, the BW and HW of the rats in groups A-D decreased significantly in contrast to those in group E (P P significantly when compared with group A (P > 0.05). The BW and HW of the rats in group D were markedly increased compared with group A (422.85 ±34.45 mg vs. 315.45 ±20.56 mg; 1355.29 ±112.23 mg vs. 1154.58 ±135.48 mg, P P The results of echocardiography Table 2 presents the results of echocardiography in the rats. Compared with E group, LVEDD and LVESD of the rats in groups A-D increased significantly (P P P (50.47 ±6.48 %) in group D was higher than group A (30.37 ±4.35 %, P P > 0.05). The hemodynamic indexes changes Hemodynamic parameters of the rats in group A had a difference in statistical significance when compared with group E (table 3). After treated with IL-10 and golimumab, ASP and ADP in group D was significantly increased when compared with group A (155.89 ±23.45 mmHg vs. 108.35 ±35.58 mmHg; 114.26 ±13.65 mmHg vs. 114.26 ±13.65 mmHg, P most markedly increased compared with group A (125.58 ±28.87 mmHg vs. 85.25 ±15.34 mmHg, P groups B and C. LVEDP in group D (5.23 ±0.68 mmHg) was most significantly decreased contrasted with group A (12.45 ±1.21 mmHg, P P Level of serum TNF-ÃŽ ± and IL-10 Compared with group E, the level of serum TNF-ÃŽ ± in groups A-D rose obviously (P P most significantly increased in group D when compared with group A (643.66 ±78.43 pg/ml vs 275.58 ±56.62 pg/ml, P DISCUSSION Heart failure (HF), as a complex clinical syndrome, is the ultimate end-result of various cardiovascular diseases and the main cause of death [7]. HF prevention and treatment have drawn more and more attention inthemedicalfield. It has been reported that TNF-ÃŽ ± played a central role in the progression of HF [12]. Studies indicated that golimumab, as a monoclonal antibody, had effective on inflammation based on inhibition on pro-inflammatory cytokine of TNF-ÃŽ ± [18, 19], moreover, the effect of TNF-ÃŽ ± in many tissue es is modulated by IL-10 [22]. In the present study, we used HF rats model to determine the effect of exogenous IL-10 combined with golimumab in the treatment for HF. The therapeutic effect of IL-10 combined with golimumab for HF in rats was evaluated according to heart function (changes of heart weight, echocardiographic and hemodynamic indicators) and the variation in the level of serum IL-10 and TNF-ÃŽ ±. To the best our knowledge, heart hypertrophy ultimately leads to HF [23], and the increase of HW/BW represents a tendency of heart hypertrophy [7]. In the present study, no obvious changes of HW/BW were observed in groups B (IL-10 group) and C (golimumab group) compared with group A (HF group). But HW/BW in group D (IL-10 and golimumab group) was markedly decreased obviously when compared with group A (HF group). These results indicate that treatment with either IL-10 or golimumab is less effective than the combination of IL-10 and golimumab for relieving heart hypertrophy. Studies indicated that treatment targeted the pathological disease such as heart hypertrophy was effective for HF [24].Therefore, our results suggest IL-10 combined with golimumab may have significant effects on prevention of HF. In addition, previous studies suggested that elevated LVEDD and LVESD and declined LVFS led to ventricular remodeling and culminated in progressive HF [25]. Based on the echocardiographic data in the present study, we found that LVEDD and LVESD decreased markedly, and LVFS increased in groups B-D compared with group A. Particularly, the most remarkable variation was observed in group D. these results suggest that IL-10 combined with golimumab are more effective inthe treatment of HF by relieving ventricular remodeling. Moreover, changes of hemodynamic parameters are regarded as an important signal of myocardial function which results in HF development [26]. In the present study, the hemodynamic measurements were improved in group D compared with groups A by increasing ASP, ADP, LVSP, LVEDP, and  ±dp/dtmax and decreasing LVEDP. Our observations were consistent with the previous findings showing that LVSP, LVEDP, and  ±dp/dtmax were increaded and LVEDP was decreased after completing the study of the HF rats. Furthermore, the previous studies declared that the deterioration of myocardial function in HF rats was more significantly alleviated based on the improvement of hemodynamic measurements after treatment [26, 27]. Notably, in our study, hemodynamic parameters in group D were improved compared with groups B and C. Therefore, the results of this study suggest that IL-10 and golimumab may have synergistic effects on improvement of myocardial function to relieve HF symptoms. Furthermore, in the present study, the level of IL-10 and TNF-ÃŽ ± were detected. The level of serum IL-10 was elevated in groups B-D compared to group A. Similarly, studies observed that an increase in IL-10 content was showed after effective treatment and suggested that improvement in cardiac function was connected with the elevated level of IL-10 [28-30]. Moreover, level of serum IL-10 in group D was higher than groups B and C, this suggest that the combination of IL-10 and golimumab can most significantly induce the elevation in the level of serum IL-10. Meantime, the results of our study showed that the level of serum TNF-ÃŽ ± in the rats of HF was significantly declined in group D compared with group A, while we noted that the treatment with IL-10 or golimumab only affected little the concentration of serum TNF-ÃŽ ± in groups B and C. This led us to hypothesize that golimumab is less effective in inhibition of the expression of TNF-ÃŽ ±, but more effective when combined with IL -10. As previous studies declared, TNF-ÃŽ ± plays a central role in initiating and sustaining the inflammatory response [31] and is a mediator of cardiac pathology acting through inflammatory pathways and activation of myocardial apoptosis [32, 33]. On the other hand, IL-10 inhibits cytokine-induced oxidative stress along with affecting the expression of inflammatory cytokines [34]. It is suggested that the imbalance between the IL-10 and TNF-ÃŽ ± in the heart may result in an inflammatory response, which plays a pathogenic role in the development and progression of HF [12]. The changes of the serum level of IL-10 and TNF-ÃŽ ± in our study suggest that IL-10 and golimumab may modulate the inflammatory processes by promoting the expressing of IL-10 and suppressing the expression of TNF-ÃŽ ±. Therefore, The combination of IL-10 and golimumab may be more effective than IL-10 or golimumab in the treatment of HF via inflammatory pathways. In conclusion, exogenous IL-10 and golimumab had synergistic effects on HF in rats based on the improvement in myocardial function and prevention of heart hypertrophy and ventricular remodeling through inflammatory pathways. Furthermore, the synergistic effect of IL-10 and golimumab is superior to the effect of treatment with IL-10 or golimumab only. Our results suggest that the combination of IL-10 with golimumab may be a promising treatment for HF patients. Further study is warranted to verify the efficiency of IL-10 combined with golimumab in human clinical trials.

An Over View Of The Beverage Industries :: Business

Formatting Problems AN OVER VIEW OF THE BEVERAGE INDUSTRIES Contributing to this industrial revolution among other industries were Manufacturing, Agricultural, Automotive, Chemical, Hotel, Banking Business Services, Real estate, Tourism and information Technology to name a few. But on such industry that has been holding onto its share of the market since its inception note in the USA - its birthplace - but all across the globe as well as the Beverage Industry. It has introduced icons that very few are oblivious to. The industry and its role in the Pakistan economy, the conditions under which it is working and the effects it has on the consumers is to remain the concern of this study. According to Richard D. Brown and George J. Petrol (1986), the history of the Beverages industry start from 1886, when Atlanta chemist Doe Pemberton developed a reddish - brown syrup with a smidgen of cocaine (for medicinal purposes) to compete with the many patent medicines and cure - all elixirs of that time. His company recommended it for the relief of hangove rs headaches, menstrual pains, and a host of other problem. One warm summer day Pemberton took some syrup down to will is venerable at Jacob's Drug Store in Atlanta. An ounce of the mixture was put into a glass, which was then filled with water and ice, creating the first Coca-Cola. The headquarters of Coca-Cola, now listed by fortune as one of the 50 top corporations in the United States, is still in Atlanta, Georgia. The actual sale and distribution of that magic elixir - which, needless to say, on longer contains cocaine - is handled largely by a number of independent bottlers. These bottlers buy syrup, mix it with carbonated water, and distribute it to retailers in their area. The number of retailers who sell Coke to the public almost exceeds counting. In this way a company with a magic formula but limited capital spread its name around the country and eventually around the globe. The organizational formula for merchandising apparently also had a bit of magic. But, of course, th e product was one that people wanted, which is perhaps the first law of success in marketing. Coke had been successful in establishing a strong loyal consumer force, on whom it still relies to this very day. Dong business was no sweat once the industry had set itself for good and the consumer's tasted veered.

Deception Essay -- Communication, Witholding Information

Deception exists in media, among prestigious universities, and perhaps most commonly in the workplace. According to Dunleavy (2010), reasons for deception in the workplace include: competitiveness, conflict, or a response to a supervisor or fellow employee (p. 241). Dunleavy develops hypotheses’, conducts experiments, and collects data to determine what is considered acceptable and unacceptable behavior as it applies to deception in the workplace. Ultimately, the reason for deceiving and the method in which one deceives, through either withholding (omission) or distortion (commission), directly effects the perception of coworkers’ credibility, power, and trustworthiness (Dunleavy, p.241). This article focuses on two different approaches of deception: withholding information versus distorting information, and how that may or may not change employees’ perception of the deceiver (Dunleavy, p.239). Dunleavy defines deception as â€Å"the conscious attempt to create or perpetuate false impressions among other communicators† (Dunleavy, p.240). Three hypotheses’ are presented in the article...

Pilot Fatigue and its role in Aviation Safety Essay

ABSTRACT The aim of this paper is to observe the growing concern of pilot fatigue and the role it plays in aviation safety. A brief assessment of the effects and possible solution to this problem will be carried out. A mention of some of the incidents from the past will also find its place in this paper. Introduction   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚     Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Aviation industry is on a growing spree and in the times to come there are going to be more and more airlines filling the sky. As we move steps further towards globalization we are going to need this service more frequently which further increases the pressure on our airlines. To tackle with this situation, especially when the availability of trained pilots is less than required, the pilots are forced to fly more frequently and for longer hours. This causes physical as well as mental stress to buildup as a result of which the efficiency of pilots decreases. This non-pathologic state resulting in physical and mental stress is known as ‘Fatigue’. Human body is always in need of rest, especially in the form of sleep, after regular intervals of time. Any lack in the required rest causes fatigue to be developed in one’s body. Due to fatigue there can be a feeling of sleeplessness, tiredness or exhaustion in a person. This feeling if effective during flight hours can be really dangerous not only for the pilot but also for the lives of the passengers traveling with him and can cause accidents. The only solution to this problem that has been known so far and will ever be known in the times to come is sufficient amount of sleep. This unfortunately is what the pilots are not getting these days and are not expected to get at least in the near future.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚     Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  The findings from the past have shown that fatigue was responsible for a large number of aviation accidents. According to a study carried out by the National Transportation Safety Board (NTSB) of flight accidents related to flight crew in US from 1978 to 1990, one of the findings related the accidents to fatigue by stating that   â€Å"Half the captains for whom data were available had been awake for more than 12 hours prior to their accidents. Half the first officers had been awake for more than 11 hours. Crews comprising captains and first officers whose time since awake was above the median for their crew position made more errors overall, and significantly more procedural and tactical decision errors.† (Strauss, n.d.). Sleep and Sleep Loss   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   It is essential for a human body to get the required amount of sleep. Sleep is considered to be an essential ingredient of our life without which it is not possible to survive. Whenever a person does not get enough sleep a signal is sent by brain to the body which results in Sleepiness. Eyelids start to get heavier and there is fatigue in the whole body. A person starts to loose concentration and may even go to sleep while he is on a job. If there is a deficiency in sleeping hours of a person and suppose every day a person looses 1 hour of sleep known as â€Å"Sleep Loss†, then it goes on accumulating over days and results in what is known as â€Å"Sleep Debt†. This debt if not cleared can cause serious problems ultimately resulting in fatigue. It has been found in researches that before flying a plane it is necessary to have sufficient amount of sleep (about 8 hours) for the pilots. If they are allowed to fly continuously without getting the required amount of rest (or sleeping hours) in between their flying schedules, then fatigue is most likely to develop in them resulting in, loss of concentration, memory   and   alertness, slow reaction time, reduced decision power, and bad mood. All these factors are basic ingredients of making mistakes and thus causing accidents. Crew rest   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   Fatigue starts to build up from the time one gets out of sleep. Development of fatigue also depends on the amount of time a person was awake before the actual flight operation. Some times there are delays in flight timings due to several reasons ranging from weather conditions to mechanical problems. This means that a pilot has been â€Å"on duty† for a long time before boarding in the plane. Although he may be flying the plane for the normal length of time but delay in flight timing has resulted in him being involved in the activities for much longer, which also results in the pilot being fatigued. Similarly there may be a case of airport congestion as a result of which a pilot cannot land and has to hover in the air for a long time or due to bad whether the plane needs to be redirected to some other destination causing him to fly for longer duration than normal. These instances also cause fatigue to be developed. Overall the fact is that ample amount of rest is essentially required by the human body to keep it fit and fatigue free.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   â€Å"A brief review of US Federal Aviation Administration (FAA) flight time and rest rules for scheduled domestic commercial carriers (US Code Title 14, part 121.471) are as follows† (Strauss, n.d.).: Crewmember total flying time maximum of: 1000 hours in any calendar year. 100 hours in any calendar month. 30 hours in any 7 consecutive days. 8 hours between required rest periods. Rest for scheduled flight during the 24 hours preceding the completion of any flight segment: 9 consecutive of hours rest for less than 8 hours scheduled flight time. 10 hours rest for 8 hours or more, but less than 9 hours scheduled flight time. 11 hours rest for 9 hours or more scheduled flight time. Diet and nutrition   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   People all over the world use coffee as a stimulant to remain awake for longer periods of time. Same is the case with pilots. To remain alert they normally consume coffee. The problem with coffee is that although it keeps a person alert, it cannot prevent body from getting tired and thus fatigued. The body still is in working condition for all these hours and hence the effect of coffee is temporary alertness and not a solution to fatigue. Also coffee is diuretic which means that it discharges more fluids than what it takes in and hence results in dehydration which is a cause of fatigue. It is always good to keep your body fit by exercising but there should be a sufficient amount of rest and consumption of water followed by it as exercises cause a lot of dehydration. However dehydration can also be caused by the fact that inside the cockpit humidity is very. There is always a balanced diet recommended for not only pilots but everyone. A pilot should always ensure a healthy diet which provides sufficient energy as well as nutrients for his body. Hypoglycemia, which is caused by low blood sugar levels, is a major cause of feeling sleepiness. A healthy diet ensures sufficient levels of blood sugar and thus energy, preventing hypoglycemia.   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚     Ã¢â‚¬ËœFinally, alcohol is known to disrupt sleep dramatically and therefore contributes to the poor quantity and quality of sleep obtained on trip nights. Alternative approaches to the use of alcohol to unwind after duty and promote sleep should be identified and offered (e.g., relaxation skills)’ (Rosekind, 1994). Other causes of fatigue   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚   One of the most important factors of causing fatigue, other than sleep debt, is the flight deck environment. Inside the deck there are a lot of factors contributing to fatigue such as lesser availability of space, variation in air flow, low atmospheric pressure, low humidity and presence of a lot of noise and vibration. Also in modern aircrafts a number of additional features and systems have been incorporated which means that the pilots have to handle multiple systems resulting in more stress. History of incidents There have been incidents in the past where fatigue has proved to not only be dangerous but also fatal. A legend in aviation refers to an incident when a pilot went to sleep with his autopilot on and found on waking up that the plane was 2 hours from the nearest destination with only one hour of fuel left. This may just be a story but in many cases researches have proved fatigue to be a cause of dangerous and fatal accidents. Some of the cases have been listed below:- In June 1999 there was a runway accident of American Airlines Flight 1420 in which 11 people died, including the aircraft captain, and many injuries among the 145 passengers and crew aboard the flight KAL Flight 801 crashed in Guam on August 6, 1997, was mainly due to a lack of situational awareness resulting in â€Å"controlled flight into terrain (CFIT).† The captain prior to flying to Guam had flown from Seoul to Australia, back to Seoul, to Hong Kong, and then back to Seoul again before his fateful trip to Guam, including only a few hours of rest in between. Cessna 177B Cardinal was flown by Joe Reid, pilot-in-command in which he, seven-year-old Jessica Dubroff and her father were killed. He suffered fatigue from the first day’s flight. On August 18, 1993, a Connie Kalitta DC-8 crashed on a 1/4-mile base leg to final. The flight crew had been on duty for 18 hours and flown nine, thereby experiencing sleep loss and a disruption of their circadian rhythms. ‘On January 2, 1989, the captain of a 707 tried to maneuver his plane to land in Salt Lake City after breaking out of the clouds at 200 feet. He dragged his left, outboard engine on the runway, leaving a 60-foot-long groove. Within the preceding 30 hours, he had been on duty for 19 hours, and flown 13 hours. He had been off duty for almost 12 hours, but was only able to get one hour of sleep in that time’ (Printup, 2000). In August 1985, the crew of a Learjet killed themselves and their passenger in a failed approach to Gulkana, Alaska. One of the contributing factors was that the company would shift the crew’s duty/rest requirements from FAR Part 135 to those of FAR Part 121, thereby disrupting their sleep patterns and inducing fatigue (Printup, 2000). Countermeasures Based on several reports a number of countermeasures have been devised to improve alertness to counter fatigue. Preventive measures like 3-4 hours of sleep can restore alertness for 12-15 hours and 10-30 minutes of sleep can do it for about 3-4 hours. Similarly it is advised to rest for 15-20 minutes after awakening and before flying. Some of other means to restore alertness are:- Consumption of high protein diet and less intake of fat and high carbohydrate food. Consumption of large quantities of fluids. Use of caffeine to work against fatigue symptoms if awake for 18 hours or less. Due rotation of flight tasks and frequent conversation with other crewmembers Maintenance of temperature inside the deck to lower levels. Frequent movement of body parts and a possible walk in the cabin. Gradually shift times for sleep, meals, and exercise to adjust to a new time zone (Strauss, n.d.). Conclusion For the safety of pilots as well as passengers the issue of pilot fatigue is of major concern. Growing number of aircrafts in the sky also means longer durations of flight for the pilots, which is a major cause of this problem. History bears the testimony to the fact that fatigue has resulted in numerous aviation accidents resulting in the loss of thousand of lives. To save more lives from getting lost there is a need to solve this problem. Allowing flexible schedules for the pilots is the only viable solution in sight at the moment. Our lives are getting busier and it would be wonderful if they become safer as well. References Dawson, Drew and Reid, Kathyryn. (August 1997). Fatigue, Alcohol and Performance Impairment.   Retrieved December 1, 2007, from http://www.eurocockpit.be/media/Dawson-Reid-1997.pdf Dr Samuel Strauss. (n.d.). Pilot Fatigue. Retrieved December 1, 2007, from http://aeromedical.org/Articles/Pilot_Fatigue.html Goode, Jeffrey H. (27 March 2003). Are pilots at risk of accidents due to fatigue?. Retrieved December 1, 2007, from http://www.eurocockpit.be/media/Goode-2003.pdf Heath, Brad and Levin, Alan. (Nov. 8, 2007). Fatigue plays role in aviation mistakes. Retrieved December 1, 2007, from http://www.azcentral.com/arizonarepublic/news/articles/1108sleepypilots1108.html Mann, Michael B. (August 3, 1999). Statement of Michael B. Mann Deputy Associate Administrator Office of Aero-Space Technology National Aeronautics and Space Administration. Hearing on Pilot Fatigue Before the Aviation Subcommittee of the Committee on Transportation and Infrastructure United States House of Representatives. Retrieved December 1, 2007, from   http://www.hq.nasa.gov/office/legaff/mann8-3.html Printup, Mark Brandon. (September, 2000). Guest Editorial: The Effects Of Fatigue On Performance And Safety. Retrieved December 1, 2007, from http://www.airlinesafety.com/editorials/PilotFatigue.htm Rosekind, Mark R. (November 1994). Fatigue in Aviation. Retrieved December 1, 2007, from http://cf.alpa.org/internet/projects/ftdt/alpmag/FATIGUE.html Samel, Alexender,   Wegmann, Hans Martin and Vejvoda, Martin. (1997). AIR CREW FATIGUE IN LONG-HAUL OPERATIONS. Retrieved December 1, 2007, from http://www.eurocockpit.be/media/Samel-Wegmann-Veivoda-1997.pdf