Unique Challenges Facing Teenage Immigrants free essay sample

Extraordinary Challenges Facing Teenage Immigrants BY Tiffany925 America was established as a country of migrants. Except for Native Americans, who originate before written history, Americans are relatives of individuals conceived somewhere else. In the course of recent years, a large number of individuals from various nations have gone to the United States looking for opportunity, harmony, and the open door guaranteed by the American Dream. Between the fifteenth and eighteenth hundreds of years individuals came to America looking for everything from more noteworthy physical space to opportunity from political or strict abuse. During this time there were additionally a great many Africans rriving to America in chains. They were sold as captives to ranch proprietors. In the twentieth century a huge number of Europeans cruised to America looking for better chances. Albeit numerous laws have been executed during the time to manage access to this nation, individuals keep on coming in incredible numbers looking for comparable dreams. Truth be told, more than one million outsiders enter the United States every year (PBS, 2009). Passig depicts the four primary challenges experienced by outsiders upon access to the U. S. as the language boundary, social challenges, passionate lopsidedness, and mental troubles. Most foreigners are not familiar with the English language. This increases their sentiments of dejection and distance. The additional weights of learning another dialect and unraveling Americas standards of conduct and social standards can present numerous passionate and mental troubles for outsiders. Passigs inquire about proposes that the ages somewhere in the range of 11 and 22 years are not ideal for adapting to these troubles. It is accepted that adolescent migrants have more trouble adapting to migration than grown-ups on the grounds that they are all the while adapting to the physiological and mental changes coming about rom age-related turn of events (Passig, Eden, Heled, 2007). As indicated by the U. S. Registration Bureau, around 400,000 individuals attempt to enter the United States unlawfully every year. Of this gathering, around 10 percent are minors. Many suffer hardships Teen Immigrants 1 coming to America. A 19-year-old secondary school understudy who emigrated from Mexico portrayed his unlawful Journey to the U. S. in a meeting distributed in The Grady Journal: l strolled a ton and we endured in light of the fact that there was no water and it was hot, A man who accompanied the gathering kicked the bucket in transit, yet when we crossed the fringe I was cheerful. My American dream had become reality. (2009). A 16-year-old understudy likewise met in The Grady Journal shared her familys experience working with coyotes to come to America from Mexico when she was eleven years of age. Coyotes are American residents that charge cash to carry outsiders into the U. S. Coyotes have been known to drop outsiders off in the center of no place, keeping their cash and leaving them to bite the dust. The understudy portrayed strolling through the desert four days. She additionally said the coyotes were terrible to her family and didn't give them water to drink. She felt miserable, terrified and orthless during her. Be that as it may, she believed herself and her relatives to be fortunate to have endure the Journey since a huge number of migrants have passed on while the U. S. what's more, later battle to fit in toa new culture (2009). Notwithstanding their strategy for Journey to the U. S. , high schooler migrants face a wide scope of acknowledgment, dismissal and negligence. They abandon companions, family and all parts of life in their local nations with expectations of improving lives for themselves in America. For some outsider young people, the progress to secondary school is the most testing of their deterrents. Other than learning another dialect, outsider young people need to make companions, and change in accordance with the diverse innovation that is utilized in American schools. Numerous worker youngsters additionally battle with clashes presented by their folks want for them to stay devoted to local social customs and their individual wants to adjust to the social conventions of American adolescents (Sridhar, 2008). For some high school migrants, American schools are their first involvement in formal instruction. In most creating nations neediness and social custom breaking point the chances of female young people to get proper instruction. Numerous families, particularly those with numerous kids, can not manage the cost of the coincidental costs related with teaching their kids. The expense of intentional commitments, regalia, books, and transport passages can make even free instruction costly. Whenever the expenses are weighed against the constrained open doors for taught females to acquire paying Jobs, most families decide to keep little girls at home. There she can add to the family unit by cleaning, cooking, gathering wood and water, and taking care of more youthful kids. As indicated by the UNICEF League Table of Girls Out of School, the level of grade young ladies out of school in the area of Sub-Saharan Africa is as high as ninety-four percent, with a territorial normal of 50%. The territorial normal of Middle East and North Africa, just as, Asia and Pacific is twenty-two percent. At the point when these numbers are contrasted with the seven percent local midpoints of the Americas rand Europe, it is obvious to see the difference among countries (UNICEF, nd). In a January New York Times article, Jennifer Medina examines the instructive effects of high school migrants in New York City schools. Medina evaluates that of the 150,000 non-English talking understudies in the city, more than 15,000 have had next to zero proper tutoring, and are regularly unskilled in their local dialects. Stephanie Grasso, an English instructor in the South Bronx, disclosed to Medina that numerous worker youngsters have not scholarly don't have an idea of being an understudy. Notwithstanding the normal difficulties migrants face, these kids have the additional inconvenience of figuring out how to be an understudy how to approach questions and comprehend things for themselves (Medina, 2009). The State of New York has built up a proper arrangement for young outsiders new to the instructive experience Students with Interrupted Formal Education. Insights from New York Citys Department of Education show a 50% expansion in the quantity of Students with Interrupted Formal Education in the course of recent years. In 2007, the graduation pace of these understudies was a unimportant twenty-nine percent against the citys by and large sixty-two percent normal. An examination was performed during this equivalent time period, through which Elaine Klein, a phonetics educator at City University of New York, followed ninety-eight Students with Interrupted Formal Education. Inside a year, Professor Klein revealed that lone forty-eight of the understudies had nations, left school for untalented Jobs, or vanished. The State of New York doesn't offer any extra financing for Students with Interrupted Formal Education. In 2008 New York City gave $2. 5 million to fifty-three schools with a huge populace of these understudies; be that as it may, this just likened to $165 dollars extra per understudy. Because of these restricted assets and the negative effect these hildren have on school evaluations, many school heads are permitting these kids to get lost in an outright flood. A head at a Queens secondary school was cited as saying Look, you need to comprehend my position: what this gathering accomplishes for my school is cut down my numbers (Medina, 2009). With numerous directors receiving a comparable demeanor to that communicated by the Queens head, many are left to contemplate the topic of who is going to serve these kids. To address this issue, Norma Vega, a New York City social specialist and previous head, built up Ellis Prep School. Ellis is an abbreviation for English Language Learners and International Support. Notwithstanding the States standard per-student financing, Ms. Vega had the option to make sure about a multi year, $200,000 award from the Institute for Student Achievement, and $76,000 from New York City. Notwithstanding instructors, Ms. Vegas staff incorporates scholastic mentors to sit at understudies sides in class to walk them through exercises. Ellis understudies are sorted out into little gatherings, aggregated so as to give more up to date understudies the advantage of working with progressively experienced understudies on which they can depend for clarifications and interpretations. The Ellis educational program incorporates English, math, history, science, and electives including violin and move. Ellis has indistinguishable graduation prerequisites from other secondary schools. Despite the fact that it is too early to write about the achievement of Ellis scholastic program, Ms. Vega is sure that it will better serve Students with Interrupted Formal Education than the conventional government funded educational system. Ms. Vega has stated, If they were totally sent to ordinary secondary schools, they would basically be lost (Medina, 2009). Meetings with adolescent foreigners demonstrate that beside all the snags they face, high schooler mmigrants see bounty as upbeat about

Aid For Developing Countries Improve Economic Growth

Introduction For centuries wealthy countries have been giving away billions of dollars to help developing countries improve their economic situation. We have found out aid given to these countries in economic need have caused positive and negative affects towards the government. The basic reasons of giving aid are to help developing countries stimulate economic growth or directly give resources to meet people’s basic needs. The question is whether this aid is helping the developing country’s government or hurting it and by how much? Aid given to these countries can include donations, projects and technical assistance. Wealthy countries give aid to developing countries to promote their own governments internationally and fulfill their economical and political agendas. Throughout history many people have not been accountable for the effects of the aid and just made sure that the aid was there. Also countries that have been giving aid to a particular country for a period of time tend t o pull out the aid because different interests arising in the donating country. This cripples the aid receiving country’s economy because the aid was holding the economy together is gone and they have to start building all over. This dependence on aid leaves the country in economic ruins when the aid disappears. Now that we have a background on aid we can see why the knowing the effect aid has on governments is so important. Determining whether or not aid is beneficial to governments is crucialShow MoreRelatedHow Can African Nations Achieve Economic Growth? Essay1104 Words   |  5 PagesMany of the globes not as advanced or â€Å"developing† nations find their place in Africa. These countries must improve upon basic fundamentals in order to be considered a developing nation. For example, a country must substantially reduce poverty in hopes of achieving their desired status. 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A Review of the World Bank’s Economic Growth in the 1990s: Learning from a Decade of Reform. Journal of Economic Literature In the past two decades, the Washington Consensus approach codified by John Williamson (1990) has been one of the most popular terms in the field of development. Consisting lists of reform agenda, Washington Consensus used to be or at least believed as a ‘rule of thumb’ policy to improve economic growth in developing countries. However, due to the undesired resultRead MoreShould The United States Increase Foreign Aid?819 Words   |  4 PagesStates increase foreign aid? This is a topic that has come up many times in the past years. When it comes to politics and the people themselves, this is a very important debate. This goes much deeper than just losing money or helping a fellow country in need. People are in need to better their country and themselves. We are all here together and aiding in one s growth can change lives all around. There are many reasons why the United States should increase foreign aid and why it is importantRead MoreInternational Trade And The Global Marketplace1428 Words   |  6 Pagesinfluences on economies as many countries are engaged to international trade in order to achieve economic growth, free trade agreement and financial liberalization has contributed to the opening up of world economies and resulted in more international trade. Countries use their comparative advantages to gain a positon in the global marketplace and achieve economic growth (Seyoum 2007). International trade is a critical resource of revenue earning for developing countries. However, the benefits realized

Definition and Examples of Climactic Order

Dilated Cardiomyopathy and The Role of Autoimmunity in...

An autoimmune response directed against heart-specific antigens has been recognized as important to the pathogenesis of DCM. Specifically, muscarinic M2AChR autoantibodies have a 25-80% occurrence in various cardiac conditions; these antibodies can be found in 18-51% of patients with idiopathic DCM (4), 40-77% of chagasic patients with heart failure and 42% of those with an unspecified condition (18, 31). A wide variety of infectious and noninfectious agents have been reported to induce similar symptoms (32, 33), and recently, a cancer patient undergoing chemotherapy with cisplatin and doxorubicin showed a DCM phenotype and the concomitant presence of serum autoantibodies against M2AChR (6). It is well established that cardiomyopathy can be recapitulated by experimental immunization with cardiac myosin plus an adjuvant or with the administration of antibodies against troponin I and the ÃŽ ²1-adrenergic receptor (33, 28, 34, 35). Similarly, we provide evidence that autoimmunity again st specific M2AChR epitopes (M2AChR-el2 and M2AChR-il3) may play a causal role in DCM. Therefore, BALB/c mice were DNA-immunized using a gene gun with plasmids encoding partial epitopes to induce potentially harmful anti-M2AChR-el2 and anti-M2AChR-il3 antibodies and establish cardiomyopathy. All mice progressively developed left ventricle dilation and dysfunction detected by echocardiography analyses (approximately 10-20 weeks post-immunization). Next, we mimicked the presence of autoantibodies

Wellness Fitness and Nutritional Plan

Question: Discuss about the Wellness Fitness and Nutritional Plan. Answer: Overview Jill is a student of a college and an athlete. She practices 4 times in a day and mainly plays on Saturday and Sundays. For improving her performances, Jill needs to work out daily. In the course of planning a female teenage athlete must know the start can be a challenging one. Jill needs to implement a proper fitness plan in her daily schedule (Desbrow et. al, 2014). Jill is a teenage female athlete who needs to plan her fitness profile along with the nutritional guide plan in a very proper way. Her fitness plan for four week can be by performing aerobic exercises, strengthening her training process, flexibility in training and ignoring or avoiding the triad in the female athlete group. After the season, Jill always faces difficulties in coping up with her studies and to lead a normal lifestyle. Therefore, she needs to plan in a very efficient way to meet up the nutritional requirements during her training and after as well. The nutritional plan for Jill is guided that deals with the total intake of the food and the total amount of water that is required to her body for maintain the physical fitness during the season and afterwards as well. (Payne Kirchner, 2014). Fitness Plan The fitness plan of Jill is given below: Aerobic Exercise Aerobic exercise is one of the efficient exercise and a must for the teenage female athlete. For maintaining a proper healthy and diet and for improving the performance, exercises must be chosen which are similar for those people who can perform well in the particular sports of their choice. Female teenage runners must incorporate running for boosting their performances and the fitness. Jogging or running can be a great way for them to leave out the boredom sand to motivate them-selves by promoting the adherence in the workout plan. Jill must incorporate aerobic exercises at least for 60 minutes for around 5-7 days in week for the best results in her health an in the athletic ability. Strength Training Process The teenage athletes especially the female can achieve the benefits from a well organized strength training program. The muscle mass can be build besides the performance of the athlete. This is the best way of boosting the health of the bone and this is very much important for the athletes those in the teenage period. Jill should include the exercises for building up of the muscle especially in the lower part of the body through squats, dead lifts and lunges. She also should lift the weights for two to three times per week. This should be done under a strong supervision of the coach. This process will give an optimal result. Flexibility Training The term flexibility means the specific joints that have the capability of producing a vast range of motion. The American Council on Exercise stated that flexibility helps in decreasing the risk of getting injured of an athlete. The improvement in flexibility can be obtained by stretching action in daily routine for about fifteen minutes. The stretching purpose after the exercise helps the athlete to prevent from the injury (Tenforde et al., 2016). Avoiding the Female Athlete Triad The daily exercises helps and participating in any sports events helps the female teen age athlete to gain some benefits and have great consequences in the field of athlete. The female teenage athlete has a significant risk in developing a female athlete triad. This is characterized by eating disorder, osteoporosis and menstruation loss. The triad can have lifelong injuries that can permanently damage the career of athlete (Tenforde et. al, 2016). Nutrition Plan Jill needs to wake up at around 6.30 am in the morning and need to drink minimum of 10 ounces water. In-taking more of water increases the energy level in the body for the strenuous exercises or for the performance that is required by the body image of Jill (Martinsen Sundgot-Borgen, 2013). The Nutrition plan for Jill can be (Parnell, Wiens Erdman, 2016): Breakfast 7.30 am 2 Egg-whites and 1 whole egg Half cup of oatmeal with one-third blueberries 16 ounces of water Mid-Morning Snack 10 am Half cup fresh fruit along with half cup low-fat cottage cheese 16 ounces of water Lunch 12.30 am 8 ounces of grilled chicken Half cup of Spinach Medium baked potato 16 ounces of water Pre-practice 45 minutes before the practice session For optimum level of energy, small snack need to be consumed before 45 minutes, like Gatorade of 15 ounce 16 ounces of water and crackers of peanut butter Gatorade of 16 ounce A banana Dinner 7 pm 8 ounce of grilled salmon 1 cup of brown rice 1 cup of steamed broccoli 16 ounces of water Before bedtime 10.30 pm 10 ounces of low fat milk Wellness Plan Stress is a mental disturbance that can hamper any individuals mental status, which ultimately disrupts all sorts of activities they are involved. The strategy for stress management for the female adolescent athlete is describes below: Plenty of Rest requires in between the performances for being fit during the performances. Managing the proper timing as per to the requirement of the fitness and to take the proper amount of food as per to the nutritional plan. Maintaining the positive attitude towards the life reduces the stress level. Recreational activities also help in reducing the level of the stress that might have developed during the poor performance (Bingham, Borkan Quatromoni, 2015). References Bingham, M. E., Borkan, M. E., Quatromoni, P. A. (2015). Sports Nutrition Advice for Adolescent Athletes: A Time to Focus on Food.American Journal of Lifestyle Medicine,9(6), 398-402. Desbrow, B., McCormack, J., Burke, L. M., Cox, G. R., Fallon, K., Hislop, M., ... Star, A. (2014). Sports Dietitians Australia position statement: sports nutrition for the adolescent athlete.International journal of sport nutrition and exercise metabolism,24(5), 570-584. Martinsen, M., Sundgot-Borgen, J. (2013). Higher prevalence of eating disorders among adolescent elite athletes than controls.Med Sci Sports Exerc,45(6), 1188-97. Parnell, J. A., Wiens, K. P., Erdman, K. A. (2016). Dietary Intakes and Supplement Use in Pre-Adolescent and Adolescent Canadian Athletes.Nutrients,8(9), 526. Payne, J. M., Kirchner, J. T. (2014). Should you suspect the female athlete triad? Is your patient's dedication to her sport putting her health at risk? This review--complete with a brief screening tool--will help you identify at-risk athletes and those whose health is already being compromised.Journal of Family Practice,63(4), 187-193. Tenforde, A. S., Barrack, M. T., Nattiv, A., Fredericson, M. (2016). Parallels with the female athlete triad in male athletes.Sports Medicine,46(2), 171-182.

Compare and Contrast Vertebrate and Invertebrate Vision Essay Example

Compare and Contrast Vertebrate and Invertebrate Vision Paper Although vertebrates and invertebrates originally evolved from a common ancestral root, both have developed very different physical utilities for vision. Both are fairly effective and have taken many millions of years to evolve. They contain many common underlying mechanisms but differ in the features used to provide them. The definition of an eye is an organ of visual perception that includes parts specialized for optical processing of light as well as well as photoreceptive neurons (Alberts). The main feature of an eye therefore, in all organisms that possess one, is the collection of photoreceptors used in converting light energy into action potentials (electrical energy). When comparing vertebrate and invertebrate vision, the two best-studied cases are the compound eye exemplified by arthropods and the simple eye used in vertebrates. The main difference between the compound and simple eye is that the compound eye uses a spatial array of lenses so that each image in a local region of visual space falls onto one or a few photoreceptors. The simple eye, however, uses a single lens to image the world onto an array of photoreceptors. Compound eyes produce mosaic images. The compound eye is made up of many optical units called ommatidiums, each of which is aimed at a different part of the visual field. Each ommatidium samples a different part of the visual field through a separate lens. In a simple eye, each receptor cell samples part of the field through a lens shared by all receptor cells. In compound eyes, each ommatidium samples an angular cone-shaped portion of the environment, taking in about 2-3i of the visual field. We will write a custom essay sample on Compare and Contrast Vertebrate and Invertebrate Vision specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Compare and Contrast Vertebrate and Invertebrate Vision specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Compare and Contrast Vertebrate and Invertebrate Vision specifically for you FOR ONLY $16.38 $13.9/page Hire Writer In contrast, each receptor of a simple eye may sample as little as 0. 2i of the visual field. In addition, the simple eye, inverts the image that falls on the retina. Since the receptive field of each ommatidium is relatively large, compound eyes have lower visual acuity than simple eyes. The mosaic image formed by a compound eye is also coarser than that of a simple eye. The simple eye in vertebrates focuses incident light in two stages. In the initial stage, incident light rays are refracted as they pass through the clear outer surface of the eye, called the cornea. They are further refracted as they pass through a second structure, the lens, and finally form an inverted image on the rear internal surface of the eye, the retina. Objects at different distance can be focussed in higher vertebrates by changing the curvature and thickness of the lens, which affects its focal length, the distance at which an image passed through the lens comes into focus. Diffraction is a property of all light and because of this, the angular resolution (resolving power) of any eye is limited by the diameter of its lens. The larger the lens diameter, the higher spatial resolution. The biggest problem for compound eyes is that the resolution is limited because the facets of the individual lens are so small. A compound eye of a given size will have a much lower resolving power than a simple eye of the same size. Optical superposition compound eyes are one way of increasing the effective lens diameter. This structure works by using several separate elements to image incident rays onto a single point, such as a single photoreceptor. This method is used in insects such as fireflies. Another way, is to use neural superposition. Simple eyes on the other hand, use a single lens, and have evolved entirely separately in the cephalopods and vertebrates. The octopus is a good example because the optical design of its eyes is remarkably similar to the vertebrate eye. The one major difference, however is that in octopus eyes, as in all fish eyes, the lens is much more powerful because it has to compensate for the loss in refractive power from the cornea, due to being underwater. Simple eyes have a much larger lens diameter which means that the spatial resolution achievable is much higher than is ever possible with a compound eye. Experiments by Kirschfeld have suggested that in order to obtain the same spatial resolution as a human eye, a compound eye would need to be about 1m across. The eye is a complex structure which has caused many arguments between evolutionary biologists and theologists. Theologists believe that the eye is so perfectly designed to harvest light, and that no intermediary design would be effective, that it must have been created by a divine designer. Biologists believe that it was created step-by-step through natural selection, and that any one step is always an improvement on the last, and thus the eye did not have to be this complex to be of benefit. This argument can be backed up by the evidence of optical diseases in which humans are handicapped in their sight, yet to them, the vision they have is better than none at all, as was a primitive form of an eye. Myopia (short-sightedness) and hypermetropia (long-sightedness) occur when the optical image of a point at infinity (i. e. he far point) falls respectively in front of or behind the retina. These errors commonly occur when the eyeball is too long, or too short, and is easily corrected with a concave or convex lens. These diseases are commonly found amongst the elderly who no longer have such deformable lens and so have difficulty varying the curvature of the lens, and thus focussing on objects at different distances effectively. This is an accommodation problem. Accommodation (discovered by Helmholz) is brought about by the ciliary body that acts on the zonular fibres that support the lens. It contains circumferential (circular) muscle fibres that allow it to act as a sphincter. The lens can be dilated by relaxing the circumferential fibres, and is said to be unaccommodated. The radial fibres of the ciliary body also act by pulling outwards on the zonular fibres that support the lens, thereby thinning it. The lens is accommodated when the circumferential fibres contract, and the lens is forced to shrink. The tension in the zonular fibres is reduced, and the lens is allowed to relax into a thicker, more curved shape, with greater refractive power. A related neuronal mechanism produces binocular convergence, in which the left and right eyes are positioned by the ocular muscles so that the images received by the two eyes fall on analogous parts of the two retinas, regardless of the distance between the object and the eyes. When an object is close, each of the two eyes must rotate towards the middle of the nose; when an object is far away, the two eyes rotate outward from the midline. Photoreceptors transduce photons of electromagnetic radiation from the visible light spectrum, into electrical signals that can be interpreted by the nervous system. The energy of the electromagnetic radiation varies inversely with its wavelength, and we perceive this variation in energy as variation in colour. The outermost layer of the vertebrate retina includes two classes of photoreceptor in vertebrates: rods and cones. There are about 100 million rods in the eye and 5 million cones. A small central area called the fovea, is densely packed with cones, but in the periphery, rods outnumber cones by 20:1. Cones function best in bright light and provide high resolution, whereas rods function best in dim light but provide much less resolution. In humans, cones mediate colour vision, and rods mediate achromatic vision. These different properties are used to expand the visual capabilities of animals living in certain conditions. For example, animals that live in flat, open environments such as rabbits, usually have horizontal regions within the retina that contain a high density of cones. This concentration of cones is called the visual streak. This region corresponds to the horizon in the visual world and is thought to confer maximal resolution in this part of the scene, allowing the animal to interpret shapes on the horizon with great precision. A receptor current exists for all sensory receptors which are usually modulated by the stimulus. In the case of vertebrate photoreceptors, the light stimulus actually reduces the circulating current, by causing the closure of ion channels. Although both invertebrates and vertebrates have eyes containing photoreceptors, they differ in their structure. Vertebrate receptor cells contain a segment with an internal structure similar to that of a cilium. This cilium connects the outer segment, which contains the photoreceptive membranes to the inner segment, which includes the nucleus and mitochondria. The photoreceptors of many invertebrates lack the ciliary structure that connects the inner and outer segments of vertebrate rods and cones and the lamellae and or stacks of disks containing visual pigment. Instead, the visual pigment is located in the microvilli formed by the plasma membrane, and these pigment-containing microvilli are organised into rhabdomeres. Visual pigments consist of 2 major components: a protein (opsin) and a light-absorbing molecule (either retinal or 3-dehydroretinal). Opsins are protein visual pigment molecules consisting of 7 transmembrane ? -helix domains. Opsins are coupled to photopigment molecules that are structurally altered by the absorption of photons, and in turn modify the opsin protein. The retinal molecule assumes two sterically distinct states in the retina. In the absence of light, the opsin and retinal are linked covalently and retinal is in an 11-cis formation. The covalent bond allows this light-absorbing molecule to act as a powerful antagonist. On capturing a photon, the retinal isomerises into the all-trans configuration, initiating a series of changes in the visual pigment, as the molecule is rendered enzymatically active. When light hits the photopigment, an intermediate metharhodopsin II forms that activates the G-protein transducin. Transducin activity closes Na+ channels and the receptor cell hyperpolarizes. Activated rhodopsin is hydrolysed spontaneously to retinal and rhodopsin which is hydrolysed spontaneously to retinal and opsin which are both used repeatedly. Studies made on the horseshoe crab, Limulus polyphemus have revealed a lot about vision. The crab has paired lateral compound eyes as well as five simple eyes: medial and lateral pairs on the dorsal surface and a single unpaired simple eye on the ventral surface. The compound eyes are typical compound eyes whereas the simple eyes are similar in structure to the simplest eye known, which consists of a shallow open pit lined with photoreceptor cells that are backed by screening pigment. Each ommatidium of a compound eye contains several photoreceptor cells. The photoreceptor cells of the Limulus compound eye are located at the base of each ommatidium. Each ommatidium lies beneath a hexagonal section of an outer transparent layer, the corneal lens. Visual transduction takes place in 12 retinular, or photoreceptor, cells. Each retinular cell has a rhabdomere, a part of the cell in which the plasma membrane is thrown into densely packed microvilli, making this the part of the cell that captures light energy. The microvilli greatly increase the surface area of the plasma membrane, which increases the probability that incident light will be captured by the rhodopsin molecules embedded in the membrane. Together, the 12 rhabdomeres of the retinular cells make up a rhabdome, which surrounds the dendrite of an afferent neuron, the eccentric cell. Depolarisations of the plasma membrane can be recorded in the retinular cells when the eye is exposed to very dim light. These quantum bumps increase in frequency as the light intensity increases (i. e. as more photons impinge on the receptors). The bumps are electrical signals generated as a result of the absorption of individual quanta of light. How can capture of a single photon lead to rapid release of so much energy? In this case, through a cascade of chemical reactions inside the cell that includes G-protein activation. Activation of the G-protein cascade occurs by diffusional contact between activated rhodopsin and molecules of G-protein, which are activated sequentially, as explained above; the activated g-protein in turn activates an effector enzyme, the PDE (phosphodiesterase); this is a 1:1 step, i. e. it has no amplification. A second stage of amplification occurs because the activated PDE is an enzyme which catalyses the destruction of cGMP. The net effect is to open ion channels, allowing cations to enter the cell. In Limulus, the receptor current through the light activated channels is carried by Na+, K+ and some Ca2+. This current causes a depolarising receptor potential. When the light goes off, the channels close again, and the membrane repolarises. The sensitivity of individual photoreceptors drops with exposure to light. This light adaptation is thought to be mediated by Ca+ ions, which enter the cells when light causes ion channels to open and which by some mechanism then reduce the current through light-activated channels. Although the Limulus eye is simple compared to that of invertebrates, the visual system is capable of generating electrical activity that parallels some of the more sophisticated features of human visual perception. The crab does however lack the degree of colour perception seen by the human eye, because it lacks the short and long wave colour pigments in its cones. It is interesting to see how two totally different mechanisms of visual perception can be so different yet interrelated in many ways, and that they have involved independently to perform the same function.

American Experience in Huck Finn Essays

American Experience in Huck Finn Essays American Experience in Huck Finn Essay American Experience in Huck Finn Essay Essay Topic: Mark Twain The Adventures Of Huckleberry Finn â€Å"All modern American Literature comes from one book by Mark Twain called Huckleberry Finn.. † claimed Ernest Hemingway, a American author and journalist. This quote represents the idea and perception of Huckleberry Finn as a defining moment in American Literature, a time when a new culture was being formed west of the Atlantic that had many different subjects and characteristics than that of the literature in Europe. What makes The Adventures of Huckleberry Finn so original and such a representation of America is that whatever Huckleberry Finn, the character, is about or can be defined by, is what America was all about. Through this complex character, Mark Twain was able to create a new American experience and show the reader all about it. The main characteristics of the American experience that Mark Twain represented through this character included a social commentary on the southern culture and its response to slavery and its general antebellum culture, the nature that defines America and how America defines its nature and the freedom from it, and the new anti-materialistic hero. The opening of the book deals with the most serious issue depicted; the idea of slavery and the response of the southerners to its injustices. The majority of the American experience of slavery and its response are shown through the relationship between the main protagonist, Huck and his friend Jim. When Jim first approaches Huck to tell him that he has run away from his master Huck replies, â€Å"People would call me a low down Abolitionist and despise me for keeping mum- but that don’t make no difference. I ain’t agoing to tell.. † (1379). In a time when it was illegal to aide slaves in their escape, Huck was just beginning to start his moral dilemma of his loyalties to the law, and his friendship with Jim. This brings about a side note on the American experience of slavery that is not as developed as the response to slavery in Huck and that is: how does a person act and feel in a society in which they have friends that can become slaves. In many Abolitionist books and essays at the time, the reader was directed to feel for the slave as a man, as a brother. They used emotions to show the hardships of the slaves and play upon the guilt of the white American to end slavery. In Huckleberry Finn, Twain asked the reader to determine how they would act on slavery when they saw their friends under servitude. This was a large issue because it brings out personal alliances with cultural alliances of the south. However, the main American experience Twain is trying to develop on slavery is not the personal relationship and whether or not slavery was a terrible issue, it was the southerners response to slavery. This is exemplified by two separate cases. The first is with slavery and Jim, and the second is with Huck’s abusive and drunken father who would â€Å"lay drunk with the hogs in the tanyard† (1359). Both of these issues were just symbols of the southern distorted culture of the time. A culture that could enslave a man, calls themselves good Christian men, and then falls asleep drunk. What is peculiar about this novel is not necessarily Twain’s feelings regarding the morality of this culture. It is fairly obvious that he disapproves of such and shows that it is a morally defunct society, but rather what makes this novel truly representative of the American experience is showing how even someone who is not morally corrupted acts upon it. Huck, who is shown through his helping of Jim and his friendship with Jim, clearly understands the injustice of slavery and the immoral acts his father does. What does he do about it though? Does he seek to transform this southern society through work or a mini-revolution? No, he just simply moves along. This is the central irony of the book, and thus represented of one of the ironies of the American experience in the 19th century. Huck Finn chooses to leave intact this society that is clearly in need of change, and just simply leaves the place behind. It shows that he is against slavery and the ideals of the south and thus won’t live in it, but he also won’t change it. This was one of the most prominent experiences of America in the 19th century. Many whites disagreed with slavery, but if it did not affect their lives, as they were not necessarily the culprit or the victim, they just went on living their lives. The most common feature of this novel is movement. While this was crucial in developing the irony that was the southern response to slavery, it is also important in itself. In this novel, the main characters are always going somewhere, leaving a place in which they didn’t like or had a bad experience, and moving on to the next. This sense of freedom from nature was feature that is distinctly American. In the novel, the river was a entral metaphor as it brought them food, their raft, but also gave them a means of transportation. The American experience of traveling for the sake of traveling and expanding yourself in nature is shown from their experiences with movement in the river. Huck Finn was a character who is always in motion, always free. This was seen by the fact that he did start out the trip trying to pr ovide freedom for Jim up the river, but when they passed Cairo he did not stop. In fact, the new route would take them to New Orleans, a slave-trading capital of the south at the time (Johnson). The freedom that nature provided Huck was seen by his depiction of the nights on the raft as â€Å"It’s lovely to live on a raft. We had the sky, up there, all speckled with stars.. † (1423). This freedom brings a release from the world of land, the towns where people were entrapped in a cycle of guns, alcohol, and racism. He does not see in moral meaning in nature like the transcendentalists of the time, rather it was an escape of the modern world, a place to have pleasant feelings. This freedom is an American experience. In just a purely physical sense, America has the opportunities for freedom. Vast lands, ample rivers, defined seasons all allow the American to seek freedom from society. This is something that was not seen in Europe as you were subjected to just your own country’s land through language, cultural, and physical barriers. This idea of jumping on a raft and finding your freedom, both spiritually as in the case of Huck and physically in the case of Jim, is something that represents a true American experience. This myth of the open frontier continued in writing for decades to come, a myth that would allow the individual American to escape the rapidly growing urban centers that were developing an uneducated middle-class. The last particularly American subject is the hero of the novel himself, Huck. Huck is envisioned as this romantic anti-society anti-inheritance hero. In coming-to-age novels of the time, many were determined to show the process the character mature, moving past their youthful selves and into a role of social acceptance of culture. Huck represents a new American subject, on who speaks as he wishes, and does as he wants. Because of his traveling lifestyle, Huck does not concern himself with inheritance or money for any matter. What mattered most for Huck in the story was the materials that made the journey possible. He was not concerned with his social class, his need for a life with a wife, kids, and money. This metaphor represents the American Anti-materialistic culture that was forming, and thus Twain depicted it as such in his story. The sense of anti-conformity culture was the subject, a view that was depicted primarily by Huck. To combat the idea that Huck was just a child, and this is how he was supposed to act, Twain introduces two characters. The Duke and Dauphin, con-artists who swindle people out of their money by performing productions represent the free nature, the anti-materialistic culture that Huck represents. While these two do act in order to obtain money, the goal of the money is not to obtain a higher social order, but to carry on in life. It supplies their thirst for fun. This was seen when after a heist, the Duke asks to count the money so that they can â€Å"take and give it to the girls† (1451). This shows that they went about their plan yes for the money, but the money was not an object that they desired; it is what it can be immediately used for that defines it. This was against the European experience of inheritance and the desire to better oneself in a Victorian fashion, and represented an American subject. Huck finds out throughout the story and the encounters with the people in the towns, how to live in order to escape the social conformity, thus creating his own identity. This idea of putting your obligations to you self-creation and fun, and not to the creation of a self that is defined by community or cultural standards was an effective approach to an American subject. In an extended metaphor, Huck Finn and his friends and acquaintances represent an American subject. Their reactions to slavery represent the blind eye and unwillingness to put about change in the southern culture of slavery and racism, a subject that would arguably represent the south to this day. At the same time, the river which took them away from their culture as opposed to fighting it, also represents the freedom of America, a subject Twain makes sure he repeats throughout the novel. Lastly, the characters themselves represent a new age of anti-materialism, a staunch contrast to the European idea of self-betterment for the sake of culture and standing. In all, these metaphors all show a new American subject. Cited: Twain, Mark. â€Å" The Adventures of Huckleberry Finn. † The Harper Single Volume American Literature. Ed. McQuade et al. New York: Longman. 1999. 1355-1522 Walter Johnson, Soul by Soul: Life Inside the Antebellum Slave Market, Cambridge: Harvard University Press, 1999, p. 2 and 6.