The Un and Their Involvement in the Rwandan Genocide Essay Example for Free

The Un and Their Involvement in the Rwandan Genocide Essay In this paper I will give a brief history of the Genocide in Rwanda, and then I will focus on one key question: What responsibilities did UNAMIR have to help, and did they successfully accomplish those responsiblities? History of Rwanda: After the start of the First World War the Belgians moved eastward and took over Ruanda-Urundi (The colonies that were previously occupied by the Germans). In 1924, the League of Nations officially awarded that land to the Belgians. The Belgians saw the differences and problems between the Hutus (the lower class farmers) and the Tutsis (mostly upper class herdsmen), and they decided to give control of the country over to the Tutsis. From then on the Tutsis began to abuse their power and they were dominant and abusive to the Hutus. In 1933 all citizens were required to have racial identity cards, which separated the two races even more. July 1962, Ruanda-Urundi gained their independence. The Urundi and Rwanda governments split and each formed separate countries. Urundi became a monarchy and changed its name to Burundi. Rwanda continued to have ethnic struggles and there was much violence. The first president elected was of the Hutu race. His name was Gregoire Kayibanda; after the election the Tutsis were made out to be the bad guys, and they were blamed for everything. Things continued to get worse for the Tutsis, and in December 1963, after a few Tutsi militias entered into Rwanda, 14’000 Tutsis were brutally murdered. In 1973, Kayibanda was removed from the Government and Juvenal Habyarimana was put in as the new president. Habyarimana was very much anti-Tutsi and in 1986 he closed the Rwandan boarders to all Tutsis and even moderate Hutus. As opposition to the Habyarimana regime many Tutsi officers from the Ugandan army, grouped up with Rwandan Tutsis and they formed the RPF (Rwandan Patriotic Front). On October 1, 1990, the officers deserted their army with all weapons and equipment in hand and moved into Southern Rwanda. This act begun what would be 4 years of the worst genocide in history. After the invasion of Southern Rwanda, the RPF moved North-East. Habyarimana defeated them with the aid of French paratroopers, provided by President Mitterrand. In December of 1990, an extremist newspaper prints â€Å"The Hutu Ten Commandments† which show the extreme hatred that the Hutu people had for the Tutsis. From that time on, the slaughtering of Tutsis continued, but there was pressure from many different countries for Habyarimana to make peace with the RPF and the Tutsi people. In 1993, there was a meeting held in Arusha, Tanzania with the hope of bringing peace to all; this was when the â€Å"Arusha Accord† was established. The â€Å"Arusha Accord† officially states that the war is over and that the remaining Tutsi refugees may return to Rwanda. The UN is called in to make sure that everything is carried out smoothly and they appoint a chapter 6 peace keeping force, UNIMAR, to see that out. On the 6th of April, 1994, the airplane carrying President Habyarimana and the President of Burundi, Cyprien Ntaryamira, was shot down. Both Presidents were killed. This marked the end of negotiations for peace and, to put it lightly, all hell broke loose in Rwanda. Between April 6th and the beginning of July, 1994 a genocide occurred that is easily one of the biggest disasters in the history of the civilized world. UNAMIR: The United Nations Assistance Mission for Rwanda (UNAMIR) was deployed during the time that peace talks were taking place. It was a Chapter 6 UN mission and was sent to keep the peace between the two rivaling groups, oversee government activities, and ensure safety until elections took place. The United Nations Observer Mission Uganda-Rwanda (UNOMUR) also played a role in the mission for Rwanda and they were treated as a Sector within UNAMIR. UNOMUR was stationed in Kabale, which was on the Ugandan side of the Uganda/Rwanda border opposite the area under RPF control; they were to monitor the flow of men, arms, and supplies from Uganda to the RPF in Rwanda. Their force consisted of MILOBs. A Chapter 6 mission mandate states: â€Å"First of all, seek a resolution by negotiation, enquiry, mediation, conciliation, arbitration, judicial settlement, resort to regional agencies or arrangements, or other peaceful means of their choice†. That was another major problem, because when the killing was going on the troops were not allowed to defend themselves because they were only there to enforce peace by negotiation and not by way of force, as stated by the mandate. The ROE also stated that the military personnel were to, â€Å"Only fire when fired upon. † UNAMIR was an ill-equipped, undermanned, and severely limited mission. The troops in Rwanda totaled 2’584 people; they had virtually no means of transportation, very limited supplies, and very few weapons. Most of the equipment that they had was out-dated and virtually unusable. The mission had to put in requests for everything ranging from toilet paper to ammunition; much of which was never provided. This was a large part of what made UNAMIR a complete failure. There was a complete lack of attention to the mission in Rwanda and no country wanted to provide resources to help. The reason that they could get no reinforcements or supplies was because of the unwillingness of Western countries to contribute anything. The exception to that is Belgium, who contributed most of the troops that were deployed into Rwanda. The different countries around the world saw the mission in Rwanda as a sideshow to the other things that were going on, for example, in the former Yugoslavia, in Somalia, etc. This unwillingness and unconcern was what allowed the Genocide to occur and what facilitated the deaths of 800,000 people in Rwanda. There are many reasons why UNAMIR failed, most of which I have attempted to explain, but it is impossible to point the finger at just one group. There were many different factors that contributed to the Genocide. UNAMIR itself tried as hard as it could under the limited supplies and the mandate that they had. Lieutenant General Romeo Dallaire did what he could with what he had, and he with the small contingent that he had saved the lives of many, but had he been given the things that he needed many thousands more could have been saved. This was not an organization, or a mission that failed; it was the failure of humanity.

Introduction To The Oil And Gas Industry Commerce Essay

Introduction To The Oil And Gas Industry Commerce Essay The production of crude oil can include up to three different stages and they are primary, secondary and tertiary. The tertiary method is also known as the Enhanced oil recovery (EOR). Different methods of enhanced oil recovery (EOR) are designed to recover oil left in the reservoir after both primary and secondary recovery methods have been implemented as per their economic limits. It is also defined as the process where some external energy, sources were introduced to enhance the production of oil from the oil field which is left out after the exploitation of the primary and secondary methods economically. These external sources can be gases, chemicals or even steam through injection systems and the processes involved are gas injection, chemical injection, thermal injection and microbial injection. The purpose of Enhanced oil recovery (EOR) is to increase oil production, primarily through an increase in temperature, pressure, or an enhancement of the oils ability to flow through the reservoir. The challenge of EOR is that the remaining oil is located in regions of the reservoir that are difficult to access, and the oil is held in the pores by capillary pressure. During primary recovery, the natural pressure of the reservoir drives oil into the wellbore, and artificial lift techniques (such as pumps) bring the oil to the surface. Only about 10 percent of a reservoirs original oil in place (OOIP) is typically produced during primary recovery. Secondary recovery methods applied to the fields productive life generally by injecting water or gas to displace oil and drive it to a production wellbore, resulting in the recovery of 20 to 40 percent of the original oil in place. Once the reservoir is half empty it is very expensive to extract and not profitable for the companies to produc e oil. At this point of time the companies may abandon the reservoir which is half full. In the past twenty years, many research organizations and oil companies have conducted extensive theoretical and laboratory EOR (enhanced oil recovery) researches to include validating pilot and field trials relevant to much needed domestic commercial application, while western countries had terminated such endeavors almost completely due to low oil prices. In recent years, oil demand has increased and now these operations have become more desirable. On an average, two-thirds of the original oil discovered in the U.S remains in the ground after conventional recovery operations. This oil represents about 200 billion barrels. Due to these factors most of the major oil companies are interested in techniques to extract this oil. And thats where enhanced oil recovery comes in. 2. CURRENT TECHNOLOGIES 2.1 Gas injection: This is the most common and effective method to improve the oil production from the field, which is noted as the most effective one for production of oil for different oil fields. This was first tried in Texas in the 1970s. This technique has been aimed to improve the pressure of reservoir, maintaining low operating costs with the increase in production of oil. The initial expenses for the basic equipment and components of gas are very high, due to which this technique has not seen widespread application. On the other hand the operating costs for this system are very low, these upfront investment costs were the barriers for the smaller independent oil companies to implement this gas injection EOR; however the investment return made possible for even independent smaller companies with the record oil prices. This method associates with nitrogen, natural gas and mainly carbon dioxide with the injection process into the field. The gas (carbon dioxide) spreads and pushes the extra oil to the place it can be extracted out easily. Gradually carbon dioxide dissolves in the oil which helps to improve the oil flow rate by reducing the viscosity of the oil. In these applications, more than half and up to two thirds of the injected carbon dioxide returns with the oil produced and is usually re-injected into the reservoir to minimize the operating costs and the remaining gas is trapped in the oil reservoir in various means. The utilization of the carbon dioxide for the gas injection EOR resulted in the prevention of plenty harmful gases from entering the natural air. C:UsersROCKYDesktopenhanced-oil-recovery.jpg 2.2 Thermal recovery: Steam injection technique has been commercially used since 1960s in California fields. As heat is required to enhance the oil flow rate, steam is sent into the reservoir through the injection system to reduce its viscosity or thin the heavy viscous oil, and improve its ability to flow through the reservoir which can be produced at the producing bore well. Dolberry oil assessed that steam associate for 52percent of present techniques used for Enhanced oil recovery, when compared to the carbon dioxide at 31percent and nitrogen 17percent. The technology called Steam Slugging contains a mixture of steam and carbon dioxide that appeared to double the production of oil within a less period of time which produced good results, making extra ten barrels per day with added advantages like water disposal and cleaning of the bore well. In this process each well is injected for about to 12 hours and then the well is left soaked for 12 to 15 hours in which the gas (carbon dioxide) compounds with the oil while and at the same time nitrogen gas helps in pulling the oil to the place where pressure is low. The extra heat produced by the extra pressure helps to loosen the oil in the pay zone. Eventually the oil produced in this process is extracted in the pay zone surroundings. 2.3 Chemical recovery: There are two types of chemicals that can be sent to the field to enhance the oil production, they are polymers and surfactants. The long chain molecules called polymers which thickens the water used to sweep oil through the reservoir into producing wells. Surfactants are detergent like chemicals that helps to obstruct droplets of oil from moving in the reservoir by lowering the interfacial tension. Implementation of this technique is generally obstructed by the cost factor in chemicals. In this process, the chemicals are sent into the different wells through injection system which helps in extracting the oil from the wells which are nearby. 2.4 Microbial enhanced oil recovery: This method is not used very often because of the high prices and the developments in this technique are very recent. This method refers to the use of micro organisms to recover extra oil from live oil fields, improving the oil production in the reserve. In this method micro organisms are introduced into the reserve to produce harmless by-products, such as gases or slippery natural substances which help to push oil out of the well. The use of micro organisms and their metabolic products to improve the oil production involves the injection of the selected microorganisms into the oil field and the subsequent stimulation and transportation of their in-situ growth products in order that their presence will help in further reduction of residual oil left in the oil field after secondary recovery is exhausted. 3. GLOBAL TRENDS Most of the oil companies aimed to decrease the exploration costs of the existing oil fields and increase their production and recoverable reserves. Many integration methods and co-operations have been established among the companies especially in the Enhanced oil recovery (EOR) area, aiming not only to increase their reserves, but also to extend the useful reservoir lifetime. In a study USA case is analyzed from 1986 to the beginning of 1998, since this is the country that has applied most of these techniques. Recently formed strategic associations in this period are also analyzed. A bibliometric analysis has been performed which shows RD tendencies of EOR method in universities, oil companies and institutions. The study shows that the EOR methods applied worldwide enhanced the production of oil and gas reserves, supported on technologies such as multilateral and horizontal wells, 3D-4D seismic techniques, simulators, nuclear magnetic resonance, materials (polymers, foams, nutrients etc) and equipment (coiled tubing) etc have been proved to be very effective. Current trends in United States enhanced oil recovery (EOR) projects are analyzed for the period from 1980-1987. The analysis is based on the U.S. Department of Energy (DOE) EOR project data base which contains information on more than 1200 projects. The National Institute for Petroleum and Energy Research (NIPER) keeps this data base up to date and analyze trends in the data under the provisions of a cooperative agreement with the DOE. The noticeable trend is the steady decline in the number of projects starting per year since 1981, which corresponds the steady decline in the oil prices during that period. On the other hand, polymer and immiscible carbon dioxide projects which peaked in number of starts in 1983. The trend seems to be clearly moving towards the lower risk projects within the screening criteria. True field experimentation with assumptions of higher risks has been decreasing. This trend has seen a change in 1986 as the planned projects appeared to have reversed the decline in project starts, however during this time sharp drop in oil prices led companies to abandon some projects and postpone others. Only the large capital investments already made has seen new starts. Despite the temporary setback, long-term EOR prospects remain good, largely because EOR remains one of the cheapest sources of new oil reserves and could play a key role in maintaining steady oil production for the future. The global market for EOR, estimated at nearly $62.5 billion (for barrels of crude oil) for 2009, has shown exciting growth since 2005 totaling $3.1 billion. Hazy regulations, technological challenges and costly implementation, kept oil companies from using EOR. However, EOR is becoming more attractive and feasible due to the government interest and investment, new technologies and availability of resources (such as CO2). It is expected that the EOR takes a good place in the world market. A number of factors fueled governments interest in EOR, the first one being the increase in oil production besides increase in the oil revenue. Countries that are able to increase their oil production are often lowering their increase in demand for oil import. It is estimated that 13 billion tons of carbon dioxide worldwide could be captured through the use of CO2-EOR, which helps to reduce industrial emissions and in turn reduce green house gases. In Texas, where EOR now accounts for 20% of its oil production, it is estimated the benefits of EOR production will result in additional revenue of $200 billion and will create 1.5 million jobs. 4. ADVANTAGES This is the only technology that combines the benefits of two traditional enhanced oil recovery methods to retrieve more oil which would have been waste remaining in the ground of no use. This method increased revenue and profits for the oil drillers who are able to extract 10percent more of the previously unrecoverable oil from an oil field. The U.S Department of energy estimates that there are approximately 240 billion barrels of oil that can be recovered with next generation enhanced oil recovery methods. Oil drillers are not the only group who would benefit from more effective oil recovery methods. It is expected that the governments and local treasuries would make $280 billion in profit in the form of taxes and royalties from the produced oil. In the process of gas injection most of the carbon dioxide is injected into ground which is produced by human activities such as oil refining or fertilizer manufacturing not only enhances the oil production, but also helps in the reduction of the green house gases which affects the atmosphere. 5. CONCLUSION Although the advantages of the Enhanced oil recovery (EOR) process has not been recognized until the recent years, the process has seen a rapid growth in the recent years which helped many companies, governments in enhancing their oil production. This process not only helps in producing more oil but also stood as an environmental friendly system which helps in eradicating the green house gases. These statements strongly support the Enhanced oil recovery (EOR) to be the future technique to recover more oil with low operating costs and environment friendly method.

Gate Control Theory Of Pain Health And Social Care Essay

Gate Control Theory Of Pain Health And Social Care Essay OA knee pain prevalence, cost to NHS etc. Physio treatment of neck painà ¢Ã¢â‚¬  Ã¢â‚¬â„¢ electro modalities, esp TENS Pain is something that everyone suffers with at one time or another. Pain can be a huge burden on employers due to absenteeism (White et al, 2005). There are many methods used to relive pain with TENS being one method. Having completed a review of current literature, it is clear that the application of tens has a significant effect on the pressure pain threshold of a subject, however no study to date has researched the effects the positioning of the TENS being applied has on the pressure pain threshold. Therefore this study has the aim of investigating whether the positioning of the electrodes at the nerve root level will affect the pressure pain threshold of the relevant dermatomal area giving rationale for the use of TENS as a pain reliving modality for injuries to the extremities. Literature Review 4k Literature Search This research is investigating the effect of transcutaneous electrical nerve stimulation at a nerve root has on the pressure pain threshold at the periphery in relation to osteoarthritis of the knee. A review of the current literature was conducted using the following databases: PubMed, ScienceDirect, MetaLib (Cardiff Universitys Electronic Resources) and Google Scholar for journals dated 1982-2012. The main key words used in the search included, transcutaneous electrical nerve stimulation, pain, osteoarthritis, knee, and periphery. Backchaining was also used to ensure all relevant literature was obtained. Introduction Osteoarthritis a very common joint disorder occurring in any joint but most commonly in the hip, knee, the joints of the hand and foot, and spine (Symmons et al. 2003). It mostly affects those aged 60 and over with approximately 40% of people over the age of 65 suffering symptoms associated with knee OA (Zhang et al., 2008) resulting in globally nearly 250 million people having osteoarthritis of the knee, 3.6% of the population (Vos et al. 2012). This resulted in osteoarthritis becoming the fourth leading cause of disability in the year 2000 (Symmons et al. 2003) and costing the NHS a total of 25 million pounds in 2008 (NICE 2008) Arthritis knee Osteoarthritis of the knee is a chronic degenerative disorder with a multifactorial aetiology (Felson, 2000). This includes general factors; such as age, sex and obesity, mechanical factors; such as alignment and trauma (cooper et al. 2000) and genetic factors (Reginato et al. 2002). Osteoarthritis of the knee is characterised by both loss of articular cartilage and by central and marginal new bone formation (subchondral sclerosis, osteophytes) (Woolf and Pfleger, 2003). There is also often thickening of the capsule and low grade synovitis resulting in alterations in biomechanics of the joint. Osteoarthritis affects the whole joint with secondary changes including ligament laxity due to articular cartilage loss and muscle weakness around the joint due to disuse respectively (Felson 2000). Osteoarthritis of the knee is associated with pain, joint stiffness and deformity, which in turn lead to limitations of daily activities for sufferers. Although there is currently no cure available, there are a number of treatment options open to sufferers to provide symptomatic relief, as well as joint function improvements. There are many non- pharmacological treatment options available such as education, rehabilitation exercises, manual therapies, acupuncture and electro-modalities such as TENS. There is also a wide range of pharmacological measures available, non-steroidal anti-inflammatory drugs, oral analgesia and topical treatments. Pharmacological treatments also include intra-articular modalities such as injections of corticosteroid and hyaluronic acid and tidal irrigation to reduce symptoms. In severe cases, where nonsurgical interventions have failed, more invasive approaches may be needed (Cooper et al 2000) including therapeutic arthroscopy and joint replacement. Models of Pain Pain something that the medical profession aims to alleviate in all patients suffering from it. In order to do this an understanding of the function of pain is needed as well as knowledge of the physiological processes the cause pain. Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage (Bonica 1979). It serves as a stimulus to motivate an individual to cease or withdraw form damaging or potential damaging situations, or to protect a damaged body part during the healing process (Winlow et al. 1984). There are three main models of pain, the cognitive-behavioral model of pain, the gate control theory of pain and the neuromatrix theory of pain. Gate control theory of pain The gate control theory suggests there is a neurological gate in the dorsal horn of the spinal cord (Melzack and Wall 1967). This gate either blocks pain signals or allows them to continue to the brain. This gate in the spinal cord differentiates between the types of fibers carrying pain signals. Pain signals travelling down the larger C nerve fibers are blocked whereas pain signals travelling done the smaller a-delta nerve fibers are allowed to pass through and therefore continue up to the brain where the pain can be perceived (cord (Melzack and Wall 1967). This gating mechanism is influenced by descending nerve impulses from the brain in response to ascending pain stimuli. Cognitive behavioral theory of pain The cognitive behavioural pain theory explores the perception of pain by relating it to more than just the physical and physiological attributes of the pain mechanism, and explores the predisposing and perpetuating factors as well as the psycho-social aspects involved in pain perception (Letham et al. 1983). This model explains why some individuals continue to experience pain after trauma has healed, or display a pain response disproportionate to the original condition. The theory states that the perception of pain is influenced by predisposing factors such as personality, coping style and previous history of illness, as well as perpetuating factors such as behaviour, emotions, and physical symptoms (Letham et al. 1983). This explains why some individuals suffer with continued pain after the original injury has resolved and are driven by fear of further pain leading to increasingly restricted activities despite the original injury being resolved, exhibit a maladaptive avoidance response. While other will experience very little pain in situations that would otherwise be excruciating, for example soldiers in battle (Letham et al. 1983) Neuromatrix theory of pain The pain neuromatrix theory is a development of the gate control theory of pain. A widespread distribution of neurons imprint a neurosignature upon nerve impulse patterns that pass through the sensory matrix (Melzack 2001). This neurosignature creates the experience of self and gives subsets of patterns that give unique experiences such as pain. The perception of pain in the brain would be as the end result of an activation of the pain neuromatrix with a characteristic pattern relating to the pain signature (Melzack 2001). This is part of a multi system response to a perceived threat. However there are many other inputs that can trigger the pain neuromatrix in the brain including movement, touch, fear and visual stimuli (Melzack 2001). This is due to the fact that the widespread neurons which make up the neuromatrix for pain perception are involved in many other activities so the pattern for pain perception can be triggered by other groups of neuromatirx being active during other activities not purely the pain neuromatrix Pain and pathways There are four basic processes involved in nociception(processing of pain), Transduction, transmission, perception and modulation (McCaffery and Pasero, 1999). Transduction begins when nociceptors (free nerve endings) of either the A-delta fibres or C fibres of the primary afferent neurones respond to noxious stimuli. A noxious stimulai occurs when tissue is damaged and inflation occurs. The nociceptors are found in the somatic structures (skin, muscles, and joints) as well as the visceral structures (organs such as gastro-intestinal tract or the liver). (Wood 2008) Although both the C fibre and A-delta fibres are Primary afferent fibres they have different cell structures and are associated with different pain qualities (table 1). Table 1: Characteristics and functions of C fibres and A-delta fibres (Farquhar-Smith 2007) C fibres A-delta fibres Characteristics: Small diameter Unmyelinated Slow conducting Receptor type: Polymodal: respond to more than one type of noxious stimuli: Mechanical Thermal Chemical Pain quality: Diffuse Dull Burning Aching Referred to as slow or second pain Characteristics: Large diameter Myelinated Fast conducting Receptor type: High-threshold mechanoreceptors: respond to mechanical stimuli over a certain intensity. Pain quality: Well-localised Sharp Stinging Pricking Referred to as fast or first pain There are three stages to the transmission of pain; first the impulse is transmitted from the site of transduction along the nociceptor fibres (first order neurons) to the dorsal horn, in the spinal cord, where both C fibre and A delta fibres terminate. In the dorsal horn they synapse with the second order neurons and which then cross the spinal cord via the anterior white commissure and ascend to the thalamus via the two main nociceptive ascending pathways. These are the spinoparabrachial pathway and the spinothalamic pathway. The thalamus then directs the nervous impulse to multiple areas of the cortex and higher brain for processing as there is not a discrete pain centre (Wood 2008). The end result of the pain transmission is the perception of pain. This is where pain becomes a conscious and multidimensional experience with affective-motivational, sensory-discriminative, emotional and behavioural components. When painful stimuli are transmitted to the brain stem and thalamus, three main cortical areas are activated, the reticular system, the somatosensory cortex, and the limbic system, each one is responsible for a different response to the pain stimuli. (McCaffery and Pasero, 1999) The reticular system is responsible for the autonomic and motor response to pain, for example, automatically withdrawing from a painful stimulus. It also plays a role in the affective-motivational response to pain, such as assessing an injury after pain has occurred. The somatosensory cortex is involved with the interpretation and perception of sensations. It identifies the location, type and intensity of the pain sensation and relates this sensation to past experiences before triggering a response. The limbic system is responsible for the behavioural and emotional response to pain as well as past experiences of pain. The modulation of pain involves altering or inhibiting the transmission of pain impulses in the dorsal horn of the spinal cord. The complex pathways involved in the modulation of pain are called the descending modulatory pain pathways (Ossipov et al. 2010). These pathways can lead to either an excitatory response (an increase in the transmission of pain impulses) or an inhibitory response (a decrease in transmission of pain impulses). Descending inhibition produces an analgesic effect by causing the release of inhibitory neurotransmitters which partially or completely block the transmission of pain impulses in the spinal cord (Ossipov et al. 2010). Endogenous pain modulation helps to explain the wide variations in the perception of pain in different people as individuals produce different amounts of inhibitory neurotransmitters. Endogenous opioids are found throughout the central nervous system (CNS) and prevent the release of some excitatory neurotransmitters, for example, substance P, therefore, inhibiting the transmission of pain impulses. Physiotherapy and treatment of Pain Transcutaneous electrical nerve stimulation (TENS) papers on TENS and Pain (critical review of the literature) Transcutaneous electrical nerve stimulation (TENS) is an electro therapy procedure the aim of which is pain relief. During treatment a low amplitude and frequency alternating electric current is passed between two electrodes placed on the body resulting in stimulation of the nervous system. Research will be reviewed examining the theory that TENS is an effective pain reliving modality. Previous studies by Chesterton et al (2002, 2003) Vance et al (2012) and Chen et al (2010) have all shown TENS to be an effective form of pain relief against blunt pressure pain with. All however have used different parameters for both the TENS settings and application sites. All of the previous studies looked at found TENS to be an effective method of pain relief based on pressure pain threshold measurement. Both of Chestertons and Vances studies found a statistically significant increase in pressure pain threshold after a twenty minute application of TENS (p=0.005, p=0.01, and p=0.002 respectively). Chen also found a significant difference in post TENS of p= Vance was the only study to look at other forms of pain measurement s outcome measures, as well as the use of a pressure pin threshold measure similar to the other studies a cutaneous mechanical pain threshold measure using Von Frey filaments and heat pain threshold measure were also used. Although using these additional outcome measures to assess the effectiveness of TEN as a pain reliving modality it was only the pressure pain threshold measure that yielded a significantly change. Therefore the results of the study can still only be extrapolated to the pressure pain reliving abilities of TENS and no other forms of pain. Both Vance and Chen explored the differences between the frequencies TENS applied. Chen uses 3Hz for low frequency and 80Hz for high frequency. Vance does not specify the actual frequency used and only states high and low frequency Tens was used with the definition of High frequency TENS >50Hz and Low frequency TENS In Chestertons 2002 also explored the differences between the frequencies of TENS applied using 4Hz as the low frequency and 110Hz as the high frequency. The results were similar to Chen with the high frequency TENS proving a more affective pain reliving modality of TENS. All three studies have good internal reliability, the same experimenter was used for every measurement, and standardised testing procedures were used. The rate of application of the algometer was kept constant when measuring the pressure pain threshold and the same point was used on each subject for the measurement. Chen and Vance, however, relied sole on the skill and consistence of the experimenter to ensure the pressure pin threshold reading was taken in the same manner for every subject. Chestertons studies used a special mounting frame for the algometer to ensure that it was perpendicular to the skin and that the rate of application was constant. This improved the internal reliability of the study as each subject will have had the reading taken in exactly the same way. Chesterton and Chen both use healthy volunteers as the subjects in their studies. Both studies have a good sample size with an equal distribution of males and females. Chen subjects have a small age range (mean  ± SD, age 26.7  ± 2.9 years) which is not representative of the population. Chestertons sample has a much larger are range (mean  ± SD, age 30 ± 7 years, range 18-57 years) which is a far closer representation of the general population and makes the extrapolation and application of the results more reliable. However both of these studies, due to only using healthy subjects, cannot be reliable extrapolated to apply to people who are not healthy. Therefore it cannot reliably be said that anyone suffering with a painful condition, be it degenerative, trauma, or surgical, will benefit from the application of high frequency TENS or that it will reduce their pain. It can only reliable be said that it will reduce the pain perceived in healthy individuals. This however is add ressed by Vance, although using smaller sample size than Chesterton all of the subjects used in the study all had a diagnosis of medial compartment osteoarthritis of the knee. Unlike the other studies Vance did not have an equal split of male to female subjects (29 male 46 female), however by using a stratified randomisation process it was ensure that each experimental group had the same ratio of male to female subjects. Therefore unlike the other studies Vances results can be reliably extrapolated to apply to a population with a diagnosis of medial compartment osteoarthritis of the knee, and high frequency TENS can be reliably used as a pain reliving modality. Random allocation of groups Not all subjects tens naive Blinding All have good baseline comparability between groups. Chen Good base line A paired t-test on this data found no significant differences (mean + SD = -1.50  ± 5.65N,  P  = .143) Chesterton 2002 Good basleine similar This was confirmed by a one-way analysis of variance (ANOVA) for pre-treatment mean MPT (P 0:19 Chesterton 2003 Good One-way analysis of variance (ANOVA) showed no significant differences in PPT, between the groups at baseline (p 0:142) Vance Bad not equal gender split 29 male 46 femle. But good that same ration in each group. Good There were no significant differences between groups in demographic characteristics, with the exception of body mass indexes (P.027). Algomiter reliability Aim(s) Hypothesis (hypotheses) Does High-TENS affect pressure pain threshold (PPT) at the periphery? Null Hypothesis: There will be no difference in the pressure pain threshold between the control group and experimental group. Methods Design This study was an experimental repeated measures clinical trial. The independent variable being assessed was transcutaneous electrical nerve stimulation. The dependent variable was Pressure pain threshold. The study included 20 people who had no previous history of knee pain and had not previously experienced TENS. Subjects attended two sessions with a 48 hour interval. In the first session subjects were given a placebo TENS and in the second a single high frequency TENS treatment. Outcome measurements were obtained before and during each treatment. Ethical approval for the study was granted by the University Ethics Committee (Cardiff University, 2012). Participants A convenience sample of 20 subjects from Cardiff University School of Healthcare was used. The inclusion criteria consisted of being a healthy subject. Subjects were screened for relevant contraindications and exclusion criteria including: pacemakers, heart disease or arrhythmias, undiagnosed pain, epilepsy, peripheral neuropathy (Fox and Sharp, 2007), history of trauma or surgery to the dominant leg in the last 6 months, medication, history of pregnancy or knowledge or use of TENS treatment (Chesterton et al., 2002). No subjects were excluded. The experimental procedure was explained to each subject who then signed a consent form witnessed by an independent person (Appendix 4). At the first session, subjects were assessed for bilateral recognition of sharp versus dull pressure at the L3 dermatome to rule out loss of sensation. Ethics Ethical approval was obtained from The School of Healthcare Studies Ethics committee Cardiff University and a single blind experiment using repeated measures was used. A risk assessment was carried out for the pilot and data collection assess risk to the subjects and the investigator using the standard risk assessment method of the cardiff university Physiotherapy department. The risk is quantified by the Risk Rating Number which is calculated by multiplying the probable frequency by the potential severity. For this research the probable frequency is unlikley scoring two and the potential severity is negligible scoring one (appendix 1). The Risk Rating number is two which requires no further action (Cardiff Univeirsity 2012). Individuals with a history of knee pain were excluded, reducing the likelihood of physical injury to the subjects during the PPT measurement process. In the event of an injury subjects would be withdrawn from the study and appropriate medical advice would be sought. The privacy and dignity of the subjects during electrode placement was ensured by using screens, and gaining informed consent before exposing the skin on the back. The information sheet given to the subjects (Appendix 3) informed them of what the study involved, and that the results would be analysed as part of this research project. Subjects were informed they were free to withdraw from the study at any time. All data was confidential and anonymous. All data stored on a computer was and password protected and anonymous. Pilot study A pilot study was conducted on 3 subjects not included in the main study prior to data collection. This was to ensure that the method to be used was satisfactory and to allow researcher to familiarize themselves with the equipment. It also allowed the researcher to estimate the time required, allowing appropriate time slots to be set. Another reason for the pilot study to be carried out was to expose any unforeseen errors or limitations in the design protocol allowing modification as necessary (Jenkins et al, 1998). The pilot study highlighted variations in subject foot placement in sitting, in turn effecting the knee positioning needed for a PPT reading to be taken. It was therefore decided to give subjects the following verbal command on how to sit, sit with your feet flat on the floor and your knees at ninety degrees, to minimize variance in knee position. The rest of the method was deemed sufficient and no further changes were made. Apparatus The pressure pain threshold was assessed using a handheld pressure algometer (Algometer commander, Jtech medical, United States) with a flat circular metal tip measuring 1.1 cm in diameter. The force was displayed digital in increments of 0.1N and applied at a rate of at 5N/s (Chesterton et al 2002). The subjects were instructed to say stop when the sensation first became painful. A practice test was first performed on the non-dominant knee to familiarize subjects with the procedure. The use of a pressure algometer for measuring pressure pain threshold has excellent test-retest reliability (r.70-94) (Fischer, 1987), and is a valid measure for deep-tissue hyperalgesia as discussed by Staud et al. (2007) Electrical stimulation was generated via a commercially available a dual channel, TENS unit (200 plus, TPN), the unit uses an asymmetrical, biphasic waveform. The pulse width was set at 50 microseconds and the frequency 150Hz, and the intensity was increased to the subjects verbal report of when the feeling became strong but still comfortable. Procedure. Before taking part in the study, all subjects were given an information sheet (appendix 3) explaining research study and what would be expected from them if they participate and completed a consent form (Appendix 4). Subjects came in on two separate occasions 48 hours apart; once for the control trial (sham TENS) and once for the application of TENS. In the first session demographic data was obtained, which included age and gender. A standard sharp/blunt discrimination test was performed, using neurotip at each stimulation site, to ensure intact skin sensation. The skin was then cleaned using an alcohol wipe before the application of electrodes (Chesterton et al., 2003). Two TENS electrodes were then placed over the L3 spinal level. Each electrode was placed over the L3 Spinal nerve root the location of which was found by palpating to the L3 spinal level (Rhoades et al. 2009). The first electrode was positioned 10mm to the left of the L3 spinal process with the second positioned 10mm to the right. The center of each the electrode was placed level with the inferior aspect of the L3 spinal process (figure 1). Experimenter 1 was responible soley for the electrode psoiting nd TENS application to ensure internal reliability. Figure 1 Subjects were seated in a comfortable upright position with feet flat on the floor. The position of the pressure pain reading was then marked bilaterally. This was done by measuring 30mm superior to the central aspect of the superior border of the patella in flexion (figure 2). Experimenter 2 was responsible solely for the positioning of the pressure pain reading and the algometer application to ensure internal reliability. Figure 2 A practice pressure pain measurement was then performed on the subjects non dominant side with subjects instructed to say stop when the sensation first became painful. At this point the experimenter immediately retracted the algometer. (Chesterton et al. 2003) This process was then repeat three times at 30 second intervals on the dominant side to establish a base line figure (Vance et al 2012). The Tens machine was then turned on and the intensity increased to the subjects verbal report of when the feeling became strong but still comfortable. For the sham TENS subjects were told that some forms of TENS were imperceptible and, they might not feel any sensation. The battery in the TENS unit was inserted the wrong way round. The unit was still visibly switched on and the intensity turned up, but no current was flowing (Chesterton et al 2003). A 30 minute timer was started as soon as the intensity was correctly adjusted. When the 30 minute time period had elapsed three further pressure pain threshold readings were taken again at 30 second intervals on the dominant side to a post treatment figure. Once these reading were taken the TENS machine was turned off and the electrodes removed. Subjects were monitored for a further 30 min after the end of the stimulation period (Chesterton et al 2002). Subjects returned for the second session 48 hours later. Data Analysis All data was entered into Windows Excel version 2010 Descriptive analysis was carried out using means, standard deviations this was presented as tables and graphs. The data was then entered into SPSS (Statistical Package for Social Sciences version 20.0). The data was interval ratio and the study investigated one group of subjects. A paired t-test was conducted to compare the percentage change in pressure pain threshold between the control and high TENS conditions. A statistical significance level of 95% (p Results The demographic data can be seen in Table 1. The following tables and graphs present both descriptive and statistical analysis of the pressure pain threshold data. All SPSS outputs can be seen in appendix 5 and raw algometer data can be seen in Appendix 6. Table 1: Demographic Characteristics of Sample N minimum maximum mean S.D Age 20 19 23 19.95 1.09904 Key: N = Number of subjects S.D = Standard Deviation A small standard deviation is seen for the age of subjects in Table 1. The male to female ratio was 1:1 with 10 female subjects and 10 male subjects. All subjects met the inclusion and exclusion criteria, and all were able to complete the study. Discussion There are two primary and related theories for explaining the efficacy of TENS in chronic or acute pain relief. The gate theory (Wall, 1965 (Melzack R, Wall P. Pain mechanisms: a new theory. Science. 150(699):971-979,1965)) proposes that pain transmission relies on a gate to the thalamus and cortex for nocireceptive information to be interpreted as pain. This theory postulates that inhibition of nocireceptors can be caused by rapid impulse activation of myelinated nerve fibers. The second related theory postulates that neurotransmitter exhaustion can be caused by rapid nerve activation outside of its refractory period, and that the temporary exhaustion of neurotransmitters would provide pain relief until such time as neurotransmitter synthesis had refilled the synaptic junctions (Kaye, 2007(Transcutaneous Electrical Nerve Stimulation: WebMD eMedicine. http://www.emedicine.com/pmr/topic206.htm January 26, 2007)). Limitations Clinical Implications Further research Conclusion

J. D. Salinger :: Biography Biographies Essays

J. D. Salinger Biographer Ian Hamilton notes that J. D. Salinger has been notoriously "famous for not wanting to be famous" (4). Born in New York in 1919 and still living today, Salinger leads a rather reclusive lifestyle, choosing to avoid the general attentions of the press, and thus making his life a difficult subject for study. His work, however, has been cherished and studied for many years. He has published many works of fiction both in book form and in magazines such as the New Yorker and Esquire. One of his most intriguing novels is Franny and Zooey, which is actually composed of two short stories bearing those names. It is one of several of Salinger's works involving the Glass family, specifically Franny and her brother Zachary, known in the family as Zooey. "Franny" relates the manner in which she arrives by train to spend an afternoon with her boyfriend Lane, whom she has not seen for some time. Lane is by nature a repressive person, one who, waiting for a train, intentionally tries to "empty his face of all expression that might quite simply, perhaps even beautifully, reveal how he felt about the arriving person" (7). It beautifully and honestly illustrates the nature of their relationship, which is far less than perfect. In the wake of the suicide of her brother Seymour (which readers can learn more about in "A Perfect Day for Bananafish" included in Nine Stories'), Franny searches for spiritual meaning in her life. Her tool in this quest is a book entitled The Way of a Pilgrim, and in following the teachings of this book, she begins to consider the lack of meaning in some of her relationships, which, in this story, alienates Lane. The majority of the story focuses on their dinner conversation, and the tension which develops between the couple is well handled by Salinger; for example, when Franny begins acting strangely, Lane "looked at her, then exhaled an overly expressive stream of smoke down at his plate. 'This is going to be a real little doll of a weekend,' he said" (24). Eventually, out of mental exhaustion, Franny passes out in the restaurant, "Zooey" picks up where "Franny" leaves off; she has been sick as a result of her increasing self-neglect. The reader meets Zooey, who spends the greater part of the story discussing with Franny her condition. Franny reveals the main point of The Way of a Pilgrim, which is to repeat the Jesus Prayer incessantly until it becomes as natural and constant a bodily process as breathing.

Analytical Chemistry :: essays research papers

Analytical Chemistry   Ã‚  Ã‚  Ã‚  Ã‚  Analytical Chemistry is the branch of chemistry principally concerned with determining the chemical composition of materials, which may be solids, liquids, gases, pure elements, compounds, or complex mixtures. In addition, chemical analysis can characterize materials but determining their molecular structures and measuring such physical properties as pH, color, and solubility. Wet analysis involves the studying of substances that have been submerged in a solution and microanalysis uses substances in very small amounts.   Ã‚  Ã‚  Ã‚  Ã‚  Qualitative chemical analysis is used to detect and identify one or more constituents of a sample. This process involves a wide variety of tests. Ideally, the tests should be simple, direct, and easily performed with available instruments and chemicals. Test results may be an instrument reading, and observation of a physical property, or a chemical reaction. Reactions used in qualitative analysis may attempt to cause a characteristic color, odor, precipitate, or gas appear. Identification of an unknown substance is accomplished when a known one is found with identical properties. If none is found, the uknown substance must be a newly identified chemical. Tests should not use up excessive amounts of a material to be identified. Most chemical methods of qualitative analysis require a very small amount of the sample. Advance instrumental techniques often use less than one millionth of a gram. An example of this is mass spectrometry.   Ã‚  Ã‚  Ã‚  Ã‚  Quantitative chemical analysis is used to determine the amounts of constituents. Most work in analytical chemistry is quantitative. It is also the most difficult. In principle the analysis is simple. One measures the amount of sample. In practice, however, the analysis is often complicated by interferences among sample constituents and chemical separations are necessary to isolate tthe analyte or remove interfering constituents.   Ã‚  Ã‚  Ã‚  Ã‚  The choice of method depends on a number of factors: Speed, Cost, Accuracy, Convenience, Available equipment, Number of samples, Size of sample, Nature of sample, and Expected concentration. Because these factors are interrelated any final choice of analytical method involves compromises and it is impossible to specify a single best method to carry out a given analysis in all laboratories under all conditions. Since analyses are carried out under small amounts one must be careful when dealing with heterogeneous materials. Carefullly designed sampling techniques must be used to obtan representative samples.   Ã‚  Ã‚  Ã‚  Ã‚  Preparing solid samples for analysis usually involves grinding to reduce particle size and ensure homogeneity and drying. Solid samples are weighed using an accurate analytical balance. Liquid or gaseous samples are measureed by volume using accurately calibrated glassware or flowmeters. Many, but not all, analyses are carried out on solutions of the sample. Solid samples that are insoluble in water must be treated chemically to dissolve them without any

Perception Reaction Paper Essay

The first thing my eyes go to is Tye’s sister Shane. She is playing with her hair, with a very skimpy bikini. She us a very pretty young teenager having fun listening to her friend’s IPod tanning up the sun rays. I see Shane’s friend in the background, not very noticeable other than she is the one picking out a song or she might be texting. I look a little more to the right and I see what appears to be a teenage boy probably 16 while his sister is maybe 14. Tye looks a little agitated at his sister maybe some jealousy. He is relaxed kicking back with something on his mind. With the rest of the people in the background there is a few other women tanning as well enjoying the beautiful weather. Also a couple boys that must have been out of the swimming pool for a bit are probably getting hot and ready to make their â€Å"shooting† heard. Everyone seems to be having a fun time but Tye’s face makes me wonder. Part 2 The way the parents tried to handle the situation is pretty much what I would do to my children. Not only is Tye confused about his life, but the family also with all the confusion dealing with a gender issue child. I believe an early teen has pretty much decided if they were â€Å"trapped† in another’s body. Tye is going to have a rough time through high school but when attending college he will be more social acceptable. I understand from personal experience of how confusing gender can be. I was a hard core tomboy but once my parents divorced I changed into a more girly tomboy, now just a tomboy on the inside. Part 3 Wow where do I start with on this article. I have always been that tomboy type but I never could imagine changing my outlooks such as my breasts and so on. Tye seems to know what he wants since a young child. I would have done the same thing by trying to make either my daughter or son the gender they were born with. I guess over time a parent would have to accept what the child decides to be no matter what the outcome is. Maybe, I would be as supportive after the fact is accepted. This article opened my eyes from the teenager’s eyes and understand how hard life can be to be socially accepted. Very good topic to write about.

Weather and its Effects

At the very least, we want to know how hot or cold it will get, or whether there will be rain or snow. Some of us live in places where severe weather can produce dangerous conditions flooding, tornados, blizzards or fogs, so we pay attention to weather related warnings. And these days, weather reports are getting more sophisticated, with pollen counts and particulates for allergy sufferers, and UP indices to tell you whether you need sunscreen. Since weather affects us so constantly, I put together this page to help understand he science of weather.I am not much interested In weather forecasting, which Is a very technical subject. This information is much more basic, about why weather â€Å"happens†, what's going on in the atmosphere, what weather-related terms we see on TV really mean, how to read weather maps. It's mostly practical Information, from a not very technical perspective. Weather and Climate Before we begin, let's differentiate between weather and climate. Weather is the state of your local atmosphere at any given time, in terms of such measurements as temperature. Wind speed, alarm pressure. Reciprocation, etc. Weather Is very specific – it's about a particular place at a particular time. It varies on a relatively small scale – for example, it could be raining in your area, while it's dry 10 miles away. It could be 72 degrees near your home, but only 65 degrees a few miles away. You could have a thunderstorm at 6 p. M. And have the sky clear by midnight. So when we're talking about weather. We are talking about a relatively small area and a very specific time. Moving to a different area, or going forward in time quickly changes the weather.On the other hand, climate is about long term averages. It concerns the same things as weather measurements like temperature, pressure, rainfall, precipitation but these measurements are averaged over a long period. If you say â€Å"the average high temperature for Boston in April is 56 deg rees†, then you are talking about climate. In order to report that average temperature, someone must have measured the high temperature each day in April, and then averaged those highs. Further, it's not enough to do that for one year, because any given year could be hotter or colder than average.So they must have measured high temperatures ACH day in April for several years, in order to calculate a multi-year average. In fact, in many places, such temperature records go back a century or more. These 100+ year records are used to calculate averages for temperatures, rainfall, weather patterns, etc. , and these long terms averages constitute the climate. It's Important to remember that weather can be very variable, but climate Is not. You could hit a high of 80 degrees on April 4th in Chicago one year, but in another year, the high on the same date might barely reach the freezing point at 32 degrees. There than a year-to-year variability. It doesn't even mean that the whole mon th of April was hotter, or the whole year was hotter. In order to make any long term comparisons, in order to show any trends, you absolutely need multi-year climate data. The Earth's Atmosphere Since weather is the condition of the atmosphere above a certain location, at a certain time of day or night, let's consider the atmosphere in more detail for a bit. The Earth's atmosphere extends from ground surface to the edge of interplanetary space.Most of this atmosphere is contained in a narrow band, about 7-10 kilometers high, which is known as the troposphere. About 80% of the mass of the atmosphere is contained within this thin band. Although 7-10 kilometers (23,000 – 32,000 feet) may not seem like a â€Å"thin† band, but it really is, if you consider how far the Earth's atmosphere extends. Technically, the Earth's atmosphere reaches half way to the moon (about 180,000 km) you have to go about that far before the density of atoms in the atmosphere equals the density of atoms typical of interplanetary space.Much of it is even visible to the naked eye. Astronauts in space can see the Corcoran, which looks like a hazy band surrounding the Earth, extending to about 100,000 km above the Earth. Of course, the upper atmosphere hundreds of miles above the Earth is unbreakable and almost empty. In fact, anything over 100 km is considered space, and if you go there, you are technically considered an astronaut by the World Air Sports Federation (this was the definition of space used for the X-Prize). The International Space Station (SIS) orbits at about 350 km.Low earth orbit, used by a huge number of satellites, extends to about 2000 km at most. These regions are commonly referred to as â€Å"space† by most people, but they are still part of the Earth's atmosphere. There is enough air up there that satellites slow down over time due to air friction, their orbits decay, and they ultimately fall back to the Earth. The SIS needs to be boosted every few months to a higher orbit, or it would also fall back to Earth. The Hubble telescope orbits at 595 km, and although it is more stable than the SIS, its orbit will also decay and fall back to Earth eventually.You have to go as far as geostationary or geosynchronous orbits (about 35,000 km) before the friction of the atmosphere (communications satellites are often in such orbits) becomes a smaller concern than gravitational perturbations. But this is still within the atmosphere. For the discussion of weather, however, we do not usually need to consider such high altitudes. 80% of the Earth's atmosphere is contained within the troposphere, a zone which extends from the surface of the Earth to about 10 km (it varies with latitude about 7 km over the poles, and about 17 km over the equator). 9% of the atmosphere is contained within the troposphere and the next zone outward – the stratosphere. The stratosphere extends from the boundary of the troposphere (known as the troposphere) to about 50 – 55 km from the surface of the Earth. Since the stratosphere), this is where weather happens. Outside this region, the air is not dense enough to display phenomena which are energetic enough to affect the weather. If the Earth's atmosphere were in complete equilibrium, we would have no â€Å"weather†. Conditions would be unchanging – there would be no day or night, no seasons, no rainfall, nothing.The source of changes in weather is changes in some other condition, some other variable. That variable is largely the Sun, although other factors also play a role. The spin of the Earth about its axis produces day and night, which means that energy input from the Sun on any given area of the Earth's surface varies cyclically reaching a peak during the day, and falling at night. This day-night cycle is a major source of weather, but it is modified and added to by many other cycles and factors as well. Some of these other factors vary by time of day or year , while others vary by location on the Earth's surface.In either case, variations are what fuel changes in the atmosphere, which we call weather. What factors cause the energy input of some local area on the Earth to change? Here are some: Latitude How far you are from the equator determines the angle of incidence of the Sun's rays at your location. This is extremely important in determining how much energy you receive from the Sun. The diagram at the right explains how this happens. Note that the diagram is not to scale, it shows the Sun as much smaller than the Earth, but that makes no difference to the explanation. The Sun is roughly spherical.It radiates energy in all directions. A very small portion of this energy is intercepted by the Earth. If we assume that the Sun radiates energy equally in all directions, we can imagine its surface (which radiates the energy) as Ewing divided into patches, measured by degrees of solid angle (usually expressed in stranding). Since the Earth is very far away from the Sun, and very small, it intercepts direct light from a very small patch of Sun. Notice the qualifier â€Å"direct†, as in â€Å"direct light†. This is important because the situation described is a simplification.In reality, the surface of the Sun emits light in all directions; therefore the Earth receives light from all parts of the Sun that are facing the Earth at a given time, not Just a single patch which is closest to the Earth. However, the density or intensity of this light is greatest when it is direct, that is, when a ray of light perpendicular to the Sun's surface intersects the Earth. So the relationship still holds – the more the direct sunlight falls upon some area of the Earth, the greater is the energy that area receives. He equator get progressively colder, because they get less direct sunlight. This creates bands or zones on the Earth's surface, with the hottest zones at the equator and the coldest zones at the poles. A temperature gradient is thus created, with high temperatures near the equator and cold temperatures at the poles. This temperature gradient drives the movement of air, which we perceive as winds. This variation is constant in time, meaning it does not change by time of the year. Latitude 50 North will always receive less installation than latitude 5 North, no matter what season of the year.It is simply a variation by location, that is, dependent upon the latitude location on Earth. Latitude is very important in setting up the permanent winds on Earth. We can divide the Earth (from North to South) into several well-marked zones. The band near the equator (about 5 ON to 5 so) is called the doldrums. It's the hottest part of the Earth, since the equator receives the most direct sunlight every year. On both sides of the equator are the tropics. These stretch roughly from the doldrums to the Tropic of Cancer (23. 5 ON) in the northern hemisphere, and to the Tropic of Capricorn (23. so) in the southern hemisphere. The tropics have a â€Å"tropical† climate – hot in the summers, mild in the winters. Beyond the tropics are the sub-tropical zones, which stretch from the Tropic of Cancer (23. 5 ON) to the Arctic Circle (66. 6 ON) in the northern hemisphere, and from the Tropic of Capricorn (23. 5 so) to the Antarctic Circle (66. 6 so) in the southern hemisphere. The subtropics usually have mild summers and cold winters. Beyond the subtropics lie the polar zones, from the Arctic Circle (66. 6 ON) to the North Pole (90 ON) in the northern hemisphere, and from the Antarctic Circle (66. so) to the South Pole (90 so) in the southern hemisphere. These are the coldest regions on Earth. Although there are many variations between different locations within the same zone (due to other differences, such as altitude, nearness to the sea, etc. Which are described below), the zones do broadly reflect the kind of climates found within. As mentioned earlier, they set up the patterns of the permanent winds – the trade winds, westerly's, polar winds. These permanent winds have a very strong effect on climate, and you can read about them in more detail on this page.Season The Earth's axis is not perpendicular to the plane of the Earth's orbit around the Sun; it is in fact tilted. The angle of tilt varies over time, but at present it is approximately 23. 5 degrees. Because the Earth revolves around the Sun, during the course of a full orbit around the Sun, each of Earth's hemispheres is at times tilted towards the Sun summer) and at other times tilted away from the Sun (Winter). The periods of maximum tilt are the solstices. In the year 2010, Summer solstice is on towards the Sun, which corresponds to summer and the longest day of the year in the northern hemisphere.Winter solstice in 2010 will be on Deck 21st at 1 1 PM (GMT), which corresponds to winter and the shortest day of the year for the northern hemisphere. As can be seen in the accompa nying diagram, a similar effect to the latitude differential described above happens during summer and winter. During summers, since the northern hemisphere is tilted towards the Sun, it receives more direct unlighted, leading to higher temperatures. During winters, since the northern hemisphere is tilted away from the Sun, it receives less direct sunlight, leading to colder temperatures. The effect is reversed in the southern hemisphere.Summer solstice in the northern hemisphere corresponds to winter solstice in the southern hemisphere, and vice versa. This seasonal effect can dramatically change weather patterns, and not Just in terms of temperatures. The change in temperature patterns across the globe shifts the high and low pressure areas of the atmosphere, which can lead to seasonal changes in winds. Indirectly, they can also affect precipitation, if for example, a winter wind which blows from land to land switches to a summer wind, which blows from sea to land. Wind blowing fr om the sea contains more moisture, which can lead to rain or snow.It's important to remember that while we think of seasons as a yearly phenomena, these changes are gradual and are happening constantly. Between the extremes of summer and winter solstice, each day the pattern changes gradually, the day becomes shorter or longer, depending upon whether the area is approaching summer or winter. While such small daily changes may seem miniscule when noninsured in terms of degrees of inclination or tilt, over the large surface of the Earth they correspond to significant shifts in the temperature zones. It's easy to calculate the magnitude of these daily changes. Since the Earth's axis is inclined at 23. Degrees, on summer solstice, latitude 23. 5 North (the Tropic of Cancer) is directly underneath the Sun (meaning, the Sun is directly overhead at noon on summer solstice day, if you happen to be at latitude 23. 5 North on that day). Similarly, on winter solstice day, latitude 23. 5 South (the Tropic of Capricorn) is directly underneath the Sun. So in the 6 months between the summer and winter solstices, the Sun changes its apparent position by 23. 5 + 23. 5 = 47 degrees in the sky. If we assume the Earth's radius to be 6400 km, then 47 degrees of latitude correspond to 47/360 = 5350 km of the Earth's surface.This means that the Earth's sun-directly-overhead-at-noon point migrates 5350 km north and south every 6 months. This is approximately 5350/180 = 29 km per day, or about 18 miles. As you can see, while it didn't seem much when we were simply looking at angles, if you warm front moving 18 miles in a day would definitely be noticed by us. So these hinges are important not Just on a seasonal basis, but also in affecting our day-to- day weather. Altitude The higher you go, the thinner the air gets. Dense air has a greater capacity to absorb and retain heat than thin air, so this is one reason why the temperature is colder at higher altitudes.However, this is insigni ficant compared to another effect, which is the cooling of air as it expands. According to the ideal gas law, the temperature of air is inversely proportional to its temperature, all else being the same. This is because as air expands under low pressure, it does work in expanding, and loses energy as ark done. Since the thermal conductivity of air is very low, it doesn't gain much heat from its surroundings, so the cooling is mostly diabetic, and well approximated by the gas law. The presence of water vapor upsets this relationship a bit, but not by a whole lot.This is the main reason why it's much colder at higher altitudes than it is at sea level. Therefore places which are near sea level and have thick, dense air are hotter than places at the same latitude which are at higher elevations. This is why the summit of Mount Kilimanjaro is covered with ice, even though it's located almost directly on the equator (about 3 so). There is a separate section here which talks about altitude- dependent atmospheric pressure changes in more detail. These changes are very important in determining the local climate of an area.Land and Oceans Land and oceans are heated differentially by the Sun. Land has a smaller thermal capacity than water. This has several interesting effects. First, it means that the same amount of solar heat will raise the temperature of land much more than it will raise the temperature of water. Therefore, during a given day land at the same latitude as water will become much hotter than the water. Since they are at the same latitude, they have received roughly the same amount of solar energy, and absorbed roughly the same amount of energy (actually, the water absorbs a bit more).But because of the difference in thermal capacities, land becomes much hotter than water with the same amount of energy. In terms of local winds, this might mean that the wind direction is from the land towards the water during the day (since air moves from higher temperature a nd low pressures towards colder temperatures and high pressures). Secondly, the greater heating or cooling of land leads to greater temperature preferential. The rate of heat gain or loss of an object depends upon the temperature differential between that object and its environment.For example, if you heat a pot of water to boiling (100 co), and then remove it from the stove and let it 10 co. If room temperature is 20 co, then the water will drop from 100 co to 90 co very quickly, but it will go from 30 co to 20 co much more slowly. This is because the temperature differential between the water and room temperature is much higher when the water is at 100 co than when it is at 30 co. Since land heats up more during he day, the temperature differential is higher, therefore land cools very rapidly as well. Water cools much more slowly, because the temperature differential is lower.We can think of it this way: land has rapid heating/cooling cycles with each day/night cycle. A large body of water, on the other hand, has much slower cycles. In fact, the water cannot lose all the heat it acquired during a summer day overnight, so it starts the next day slightly warmer than it was the previous morning. So as summer progresses, large bodies of water get progressively warmer, and they maintain this eat through the night hours, when the land cools down. For this reason, oceans don't have diurnal peaks and troughs in their temperature like the land; instead, they have seasonal peaks and troughs in their temperature.These things produce very significant effects on weather patterns. The general direction of the effect is towards the moderation of temperatures. Since the water heats more slowly but retains heat longer than land (and cools more slowly but retains coldness longer than land), the presence of oceans tends to moderate the climate of nearby land masses. At the same latitude, an area will be much hotter in he summer and colder in the winter if it's far away from th e sea. Nearness to the sea will moderate temperatures, making it both less hot in the summer and less cold in the winter.Even smaller bodies of water such as lakes can have a moderating effect on temperatures. Check the weather map of the Midwest US, and on many days you'll see that the temperature at the lake front in Chicago is higher or lower than out in the suburbs (by a few degrees), simply because Lake Michigan cools the lake shore during the summers, and warms it during the winters. Smaller bodies of water can also produce local diurnal winds, such as a breeze from lake to shore in the mornings, and a breeze from shore to lake in the evenings.Again, this has to do with the differential heating of land as compared to water during the day. Topography The physical relief of land areas has much to do with weather. There can be many reasons for this. One is simply altitude – mountainous areas will be cooler than areas at the same latitude which are nearer to sea level. But in addition, variation of the terrain can influence wind patterns and therefore the weather. One example is mountains as a barrier to wind flow. If a mountain range interrupts revealing winds, air is forced upwards to pass over the mountains.As it moves upward, it cools down. Since the water carrying capacity of air diminishes as it cools, this results in precipitation on the windward side of the mountains. Conversely, once Therefore, the leeward side of the mountains will be in â€Å"shadow† and receive much less rainfall than if there had been no mountains along the way. This effect can be seen almost anywhere in the world where there are mountains that interrupt some seasonal wind flow. It is very dramatic in the Himalayas in India, where the monsoon winds from the south meet the Himalayas.On the windward side, in the foothills of the Terra, there is very heavy rainfall. Chirruping in the Indian state of Megalith has historically been the wettest place on Earth (450 inches of rain on average per year), as the monsoon winds from the Bay of Bengal hit the Kiosk hills and are forced to rise and shed water. Conversely, the Tibetan plateau, on the leeward side of the Himalayas is very dry, with less than 18 inches of rain/ snow per year. There are other effects of topography as well. Flat land which is uninterrupted by hills or mountains allows wind to build up over long stretches.This is why the Midwest and plains states in the US are generally quite windy. Land which is more uneven breaks up lower level winds, so wind speeds are slower and winds are not as sustained. If a large area of flat lands then borders a hill or mountain range, these high winds can get channeled into valleys between the hills, and reach even higher velocities. You can see this effect on a much smaller scale even with man-made structures. Streets form canyons between skyscrapers in downtown areas of major cities, and wind is channeled through these â€Å"canyons†, reaching much higher speeds Han out in the suburbs.If you've walked through downtown Chicago or downtown Manhattan, you may have experienced this yourself. Low lying troughs, on the other hand, may have days when the air stagnates and does not move, since it is blocked by higher elevations surrounding the trough. Ocean Currents Water, like air, is a fluid medium, which can move from one place to another under temperature differentials. Just as there are winds in the atmosphere, there are water currents in the oceans, which carry warm water or cold water from one place to another, sometimes for thousands of miles.One well-known example of such a current is the Gulf Stream, which carries warm water from the Caribbean to near the shores of northern Europe. The Gulf Stream is largely responsible for the migration of populations into Europe after the last ice age. Without the Gulf Stream, Europe would probably be a sparsely populated wasteland. Consider London, which in terms of latitude is sligh tly farther north than Calgary in Canada. The average January low temperature of Calgary is 8 OF, but the average January low temperature of London is 41 OF. This is a huge difference, and the Gulf Stream is responsible.While latitudes comparable to England and northern Europe are almost tundra-like across Canada or Asia, they are quite warm and habitable in cultures traditionally depend upon hunting, since agriculture is insufficient to provide the necessary calories. But in Europe, there is extensive farming, which can support much larger population densities. The Gulf Stream has made it possible; it is a critical part of Rupee's habitability. Ocean currents are one of the most important contributors to climate, but the topic is fairly complex. I have written a brief explanation here, which you should really read before going ahead.