Allelic Drift - Definition

Genetic Drift / Allelic Drift - Definition Definition: Genetic drift is defined as the changing of the number of available alleles in a population by chance events. Also called allelic drift, this phenomenon is usually due to a very small gene pool or population size. Unlike natural selection, it is a random, chance event that causes genetic drift and it depends solely on statistical chance instead of desirable traits being passed down to offspring. Unless the population size increases through more immigration, the number of available alleles gets smaller with every generation. Genetic drift happens by chance and can make an allele disappear completely from a gene pool, even if it was a desirable trait that should have been passed down to offspring. The random sampling style of genetic drift shrinks the gene pool and therefore alters the frequency the alleles are found in the population. Some alleles are completely lost within a generation due to genetic drift. This random change in the gene pool can affect the speed of evolution of a species. Instead of taking several generations to see a change in allele frequency, genetic drift can cause the same affect within a single generation or two. The smaller the population size, the greater the chance of genetic drift occurring. Larger populations tend to function through natural selection much more than genetic drift due to the sheer number of alleles that are available for natural selection to work on as compared to smaller populations. The Hardy-Weinberg equation cannot be used on small populations where genetic drift is the main contributor to diversity of alleles. Bottleneck Effect One specific cause of genetic drift is the bottleneck effect, or population bottleneck. The bottleneck effect occurs when a larger population shrinks significantly in size in a short amount of time. Usually, this decrease in population size is generally due to a random environmental affect like a natural disaster or spread of disease. This rapid loss of alleles makes the gene pool much smaller and some alleles are completely eliminated from the population. Out of necessity, populations that have experienced population bottleneck increase the instances of inbreeding to build the numbers back up to an acceptable level. However, inbreeding does not increase diversity or numbers of possible alleles and instead just increases the numbers of the same types of alleles. Inbreeding can also increase the chances of random mutations within DNA. While this may increase the number of alleles available to be passed down to offspring, many times these mutations express undesirable traits such as disease or reduced mental capacity. Founders Effect Another cause of genetic drift is called founders effect. The root cause of founders effect is also due to an unusually small population. However, instead of a chance environmental effect reducing the numbers of available breeding individuals, the founders effect is seen in populations who have chosen to stay small and do not allow breeding outside of that population. Often, these populations are specific religious sects or offshoots of a particular religion. The mate choice is significantly reduced and is mandated to be someone within the same population. Without immigration or gene flow, the number of alleles is limited to only that population and often the undesirable traits become the most frequently passed down alleles. Â   Examples: An example of founders effect happened in a certain population of Amish people in Pennsylvania. Since two of the founding members were carriers for Ellis van Creveld Syndrome, the disease was seen much more often in that colony of Amish people than the general population of the United States. After several generations of isolation and inbreeding within the Amish colony, the majority of the population became either carriers or suffered from Ellis van Creveld Syndrome.

Msc IT Project Proposal - Title to be decided Thesis

Msc IT Project Proposal - Title to be decided - Thesis Example Current paper focuses on the methods used by a firm that operates in a specific industry, this of the martial arts, in order to improve its communication with its customers and therefore increase its performance. The firm under examination is a Judo club which is not well established in the market; it has entered the market rather recently – one year ago – and it seeks to increase its performance by improving its communication with its customers. It can be assumed therefore that the resources available for the achievement of the above targets will be limited. The chances for the achievement of the relevant plan will be explored and analyzed using a series of appropriately customized research methods. As already noticed above, the firm’s resources that are available for the realization of the relevant project – development of a communication website – are limited. The short presence of the firm in the market could be regarded as the main reason for the lack of necessary resources; however, there are firms that are developed quite quickly even if they operate for a short period within a particular market – this is the case of firms that use all resources available – referring not to the internal resources but also to the external ones, e.g. the funding options available in a specific market. It seems that the specific firm didn’t manage to ‘gain’ the support of the market until now (probably because no appropriate research was made to this direction). For this reason, it is necessary that all available resources of the firm will be employed in the particular effort trying to ensure the increase of its competitiveness within th e particular industry. Currently, the systems available for the completion of the specific project – communication website – are rather limited. The firm’s operation is based on a simple IT network consisting from 3 desktops that communicate through an

The Twelve Steps of Alcoholics Anonymous Assignment

The Twelve Steps of Alcoholics Anonymous - Assignment Example As I entered the place, I found people sitting and standing randomly. I grabbed a chair near the window and saw people; some saying hello, some stopping, and some just keeping to themselves. The meeting commenced at the chairperson read the Preamble, and led the prayer. Different members read the brief literature of AA afterward. In this Step Meeting of 10 minutes, I sat and listened to the â€Å"steps†. My curiosity about the AA thing was increasing. The Chairperson declared the step that would be discussed. I was so surprised to see that the attendants of the meeting were unashamed apparently that I cannot really recall what step that was. After reading the step chapter from Twelve Steps and Twelve Traditions, the attendants were asked if they had any previous experience related to the step and if any of them would take that as an opportunity to share it with others.   The most interesting part of the whole meeting was to watch others narrate their personal experiences and struggles with alcohol and drawing their relation with the step under discussion. People started talking during the meeting. They started off by telling their name and status as alcoholics to each other. One after another, every attendant stood up, said his name, narrated his story, received audience’s applauds and settled down. â€Å"In the simplest form, the AA program operates when a recovered alcoholic passes along the story of his or her own problem drinking, describes the sobriety he or she has found in AA and invites the newcomer to join the informal Fellowship† (alcoholics-anonymous.org.uk, 2014).   Of all the different sorts of manifestations, I found that the most prominent causes of alcohol dependency were sociological and psychological.

Commercial Fishing in the Gulf of Mexico Research Paper

Commercial Fishing in the Gulf of Mexico - Research Paper Example The mainland shore of the Gulf is shared by the United States and Mexico and it covers more than 4000 miles from Cabo Catoche in the Yucatan Peninsula in Mexico to Florida Keys the US (GMP, 2011). According to GMA (2008, p5), the Gulf of Mexico covers an estimated area of about 600,000 square miles. Due to its unique location, the Gulf is rich in diverse natural resources that play a critical role in defining the economic, environmental, political and social dimensions in the region. According to GMA(2008, p2), the gulf offers aquatic resources that include recreation, navigation, commercial fishing, oil and natural gas in addition to rich habitats for diverse marine life. This paper investigates the problems associated with commercial fishing in the Gulf of Mexico and their impacts on the American culture. According to GMA(2008, p7), the five US states bordering the Gulf of Mexico have a total gross domestic product of over $2.2 trillion and much of the economic activities depend on the natural resources from the gulf. The economic contribution of the Gulf of Mexico to the United States is significant. ... These ports provide the country with a good infrastructural network of enhancing international trade. The population growth in the gulf region has been increasing, recording 103% growth from 1970 to 2008 (GMA, 2008, p 11). The region is highly attractive to job seekers and retirees because of the availability of many opportunities and favorable climatic conditions. By 2015, Polunin (2008, p 37), predicts population increase of 10 % in the gulf region compared with an average of 7% in total population of the United States. The rapid population growth in the region has resulted to a vibrant construction industry to cater for the housing needs. According to GMA (2008, p 11), 30 percent of the leading counties in building residential houses are located in the gulf coast region. The Gulf of Mexico is prone to natural disasters such as hurricanes but residential developments are on the increase. In addition to residential buildings, construction of seasonal homes is also gaining prominence in the gulf region. This is attributed to the scenic attractions that draw people from all over the country for vacations (GMP, 2011). The Gulf of Mexico is one of the largest water bodies in the world and it consists of a wide marine diversity ranging from shrimps to unexploited corals in the deep horizons of the water. Due to the wide ecological diversity of the region, many environmental activities have been established in the Gulf of Mexico. They include national parks, wildlife preservation regions and wetlands. According to GMA (2008, p13), half of all the wetlands in United States are located in the coastal areas in the gulf. The wetlands provide suitable habitats for a wide variety of biological resources including sea turtles, fisheries, nesting waterfowl in

Chemicals in Disinfectants and Sterilants

Chemicals in Disinfectants and Sterilants Discuss the uses and modes of action of chemicals used as disinfectants and sterilants Disinfectants and sterilants have been available in a variety of forms for a great number of years. The pioneering work of Joseph Lister and Ignaz Semmelweis effectively opened the door to the range of chemicals that we have available today. Phenols (carbolic acid derivatives), mercuric chloride, chlorides, hypochlorites and iodine were the first major groups to be utilised. The quaternary ammonium compounds rose to prominence in the 1930s (Russell, A. D. 2002 [I]). The first detailed studies on the subject of mode of action were published by Cooper, who described the action of phenols as denaturing bacterial proteins as their main mode of operation (Cooper E A 1912) Knaysi expanded this work further by suggesting that the order of death amongst cells was determined by some form of resistance (Knaysi G 1930) and that this might be linked to the protein structure of the cell wall (Knaysi G et al. 1930). Further work on phenol suggested that resistance of E.Coli was the same at virtually any concentration of phenol (Jordan, R. C et al. 1944) and this lead to the development of the concept of specific enzyme inhibition. (Roberts, M. H et al. 1946) The term biocide is becoming more commonly used to describe the generic group. Russell (A D 2002 [II]) makes the comment that, until recently, two views permeated the field. One was that as long as they were effective, there seemed little merit in determining how they arrived at their inhibitory or lethal effects and secondly, that they were believed to act as protoplasmic poisons and, as such did not merit much attention. We will present evidence to dispute both of these views. Specific work on the mode of action of the biocides has been sporadic until comparatively recently. Gram-positive and -negative bacteria appear to have received the lion’s share of the research with less on the mycobacterium, less still on fungal and viral agents (Maillard, J.-Y et al. 1997), and few quality papers on the protozoa. (Turner, N. A et al. 1999). We know even less still on the ability of biocides to inactivate prions. (Taylor, D. M 1997). Because of the wide range of potential biocidal (and biostatic) agents, it is not possible to even begin to tackle the question of mode of action in this essay on any but the most general terms There are a number of current research issues such as the question of why it is that MIC’s of some cationic biocides such as chlorhexidine is similar for both mycobacterium and staphylococci yet they appear to possess low mycobacterium potency but are rapidly lethal to the staphylococci (Russell A D 1996) Current considered opinion is that the majority (if not all) cells are not killed by a disactivation of a single target enzyme by the biocide. (Hugo, W. B. 1999) Specific examples would be that enoyl reductase, (an enzyme involved in fatty acid synthesis) is totally inhibited by triclosan it is a combination of other intracellular disruptions that prove to be lethal to the cell. (Suller, M. T. E et al. 2000) A number of researchers have commented on the apparent similarities between the disinfectants and sterilants group and the antibiotic group in terms of their effect on bacteria. To give specific examples, filament formation in Gm-ve. Bacteria is induced by both antibiotics (eg. ß-lactams andfluoroquinolones) and biocides (eg.phenoxyethanol and chloroacetamide) (Ng, E et al. 2002). Equally we have mentioned the action of triclosan on enoyl reductase, but this enzyme is also inhibited by isoniazid. (McMurry, L. M et al. 1999). A third category of similarity would be that the cell autolysis observed with both the phenols and some mercuric compounds is apparently the same as the processes observed with exposure to penicillin. (Hugo, W. B. 1999). Other research groups (McKellar, R. C et al. 1996) have noted that exposure to some biocides can render a pathogen more susceptible to the action of antibiotics. It was postulated (although not proved) that this effect may be due to a structural change resulting in differing permeability in the cell wall of the microbe. (Morris, A et al. 1991) It is not intended to imply that because these mechanisms appear similar that they are actually the biochemically or physiologically the same. Further research is needed to clarify these points We have made comment on the apparent ability of some biocides to interfere with the integrity of the cell wall. In the case of the bacteria and fungi this may be a useful attribute to exploit, but it is a different matter in dealing with viral (and phage) vectors. The problem being that if the viral envelope which is usually derived from the host cell is damaged, then this can result in the liberation of intact viral nucleic acid which, in itself, may be infective. (McClure, A. R et al. 1992) If we consider one mechanism in some detail by way of an example, we could consider the action of chlorhexidine. This has been shown to produce a very rapid lethal effect ( about 20 seconds) in both E.Coli and Staph. Aureus. (Denyer, S. P. 1995). It has been shown to produce damage to the outer cell membrane, but this action does not directly cause cell death. (El-Moug, T et al. 1985) Chlorhexidine then crosses the damaged membrane by passive diffusion and causes leakage of the intracellular components. The cause of cell death is the inactivation of the intracellular constituents by protein denaturation of their controlling enzyme systems. This causes a further congealing of the cytoplasm and this reduces cellular leakage. This is the so-called biphasic mechanism of action of chlorhexidine. (Longworth, A. R. 1971). There was a suggestion that chlorhexidine bound and inactivated the membrane-bound ATPase. It thereby disrupts the membrane potential and this is thought to be the prime mechanism of cell death .(Barett-Bee, K et al. 1994) In conclusion, we have considered some of the mechanisms that are thought to be active in the bioactivity of disinfectants and sterilants. In doing so we should also consider the question of resistance. Many pathogens have efflux systems which can combat or eliminate biocides from their environment. These can work at comparatively low concentrations of the biocide. But it opens up the possibility of the development of biocide resistance in those cells which survive the initial exposure (possibly due to incomplete treatment or peripheral exposure to low concentrations of agent). This mechanism selectively favours the emergence of biocide-resistant pathogens. (Azachi, M et al. 1996) This issue has prompted calls for the rotation of disinfectants and sterilants in hospitals and elsewhere. (Benarde, M. A et al. 1967). The use of one disinfectant should ideally be replaced with another which has a completely dissimilar mode of action. This is one argument for the study of the mode of action of both disinfectants and sterilants. Other arguments for studying the mechanisms of action of the biocides are many, not least is the fact that the knowledge of the mechanism of how a particular biocide can exert its effect can lead to the selective development of new targeted compounds with greater efficiency. An example of this process is the development of ortho-phthalaldehyde (OPA), which was specifically developed and adapted from â€Å"older† compounds. (Behr, H et al. 1994) References Azachi, M., Y. Henis, R. Shapira, and A. Oren. 1996.  The role of the outer membrane in formaldehyde tolerance in Escherichia coli VU3695 and Halomonas sp. MAC.  Microbiology 142:1249-1254 Barett-Bee, K., L. Newboult, and S. Edwards. 1994.  The membrane destabilizing action of the antibacterial agent chlorhexidine. FEMS Microbiol. Lett. 119:249-254 Behr, H., M. E. Reverdy, C. Mabilat, J. Freney, and J. Fleurette. 1994.  Relation entre le niveau des concentrations minimales inhibitrices de cinq antiseptiques et la prà ©sence du gà ¨ne qacA chez Staphylococcus aureus.  Pathol. Biol. 42:438-444 Benarde, M. A., W. B. Snow, V. P. Olivieri, and B. Davidson. 1967.  Kinetics and mechanism of bacterial disinfection by chlorine dioxide.  Appl. Microbiol. 15:257-265 Cooper, E. A. (1912).  On the relationship of phenol and m-cresol to proteins: a contribution to our knowledge of the mechanism of disinfection.  Biochemical Journal 6, 362–87. Denyer, S. P. 1995.  Mechanisms of action of antibacterial biocides.  Int. Biodeterior. Biodegrad. 36:227-245. El-Moug, T., D. T. Rogers, J. R. Furr, B. M. A. El-Falaha, and A. D. Russell. 1985.  Antiseptic-induced changes in the cell surface of a chlorhexidine-sensitive and a chlorhexidine-resistant strain of Providencia stuartii.  J. Antimicrob. Chemother. 16:685-689 Hugo, W. B. (1999).  Disinfection mechanisms. In Principles and Practice of Disinfection, Preservation and Sterilization, 3rd edn, (Russell, A. D., Hugo, W. B. Ayliffe, G. A. J., Eds), pp. 258–83.  Blackwell Science, Oxford Jordan, R. C. Jacobs, S. E. (1944).  Studies on the dynamics of disinfection. I. New data on the reaction between phenol and Bact. coli using an improved technique, together with an analysis of the distribution of resistance amongst the cells of the bacterial population studied.  Journal of Hygiene (Cambridge) 43, 275–89. Knaysi, G. (1930).  Disinfection. I. The development of our knowledge of disinfection.  Journal of Infectious Diseases 47, 293–302. Knaysi, G. Morris, G. (1930).  The manner of death of certain bacteria and yeast when subjected to mild chemical and physical agents.  Journal of Infectious Diseases 47, 303–17. Longworth, A. R. 1971.  Chlorhexidine, p. 95-106. In W. B. Hugo (ed.), Inhibition and destruction of the microbial cell.  Academic Press, Ltd., London, England. Maillard, J.-Y. Russell, A. D. (1997).  Viricidal activity and mechanisms of action of biocides.  Science Progress 80, 287–315 McClure, A. R., and J. Gordon. 1992.  In vitro evaluation of povidone-iodine and chlorhexidine against methicillin-resistant Staphylococcus aureus.  J. Hosp. Infect. 21:291-299 McKellar, R. C., McKenzie, C. N. Kushner, D. J. (1996).  Correlation of resistance to proflavine and penicillin in Escherichia coli. Antimicrobial Agents and Chemotherapy 10, 765–7   McMurry, L. M., McDermott, P. F. Levy, S. B. (1999).Genetic evidence that InhA of Mycobacterium smegmatis is a target for triclosan. Antimicrobial Agents and Chemotherapy 43, 711–3 Morris, A. Russell, A. D. (1991).  The mode of action of novobiocin. In Progress in Medicinal Chemistry, (Ellis, G. P. West, G. B., Eds), Vol. 41, pp. 39–59.  Butterworths, London.   Ng, E. G.-L., Jones, S., Leong, S. H. Russell, A. D. (2002).  Biocides and antibiotics with apparently similar actions on bacteria: is there the potential for cross-resistance?  Journal of Hospital Infection 2002 Vol 3 pgs 239-242 Roberts, M. H. Rahn, O. (1946).  The amount of enzyme inactivation at bacteriostatic and bactericidal concentrations of disinfectants.  Journal of Bacteriology 42, 639–44. Russell, A. D. (1996).  Activity of biocides against mycobacteria.  Journal of Applied Bacteriology, Symp. Suppl. 81, 87S–101S. Russell, A. D. 2002 (I)  Introduction of biocides into clinical practice and the impact on antibiotic resistant bacteria.  Journal of Applied Microbiology, Symp. Suppl. 2002 Russell A D 2002 (II)  Mechanisms of antimicrobial action of antiseptics and disinfectants: an increasingly important area of investigation  Journal of Antimicrobial Chemotherapy (2002) 49, 597-599 Suller, M. T. E. Russell, A. D. (2000).  Triclosan and antibiotic resistance in Staphylococcus aureus.  Journal of Antimicrobial Chemotherapy 46, 11–8 Taylor, D. M 1997.  Inactivation of unconventional agents of the transmissible degenerative encephalopathies. In A. D. Russell, W. B. Hugo, and G. A. J. Ayliffe (ed.), Principles and practice of disinfection, preservation and sterilization, 3rd ed., in press.  Blackwell Science, Oxford, England. Turner, N. A., Russell, A. D., Furr, J. R. Lloyd, D. (1999).  Editorial: Acanthamoeba spp., antimicrobial agents and contact lenses.  Science Progress 82, 1–8

Pain :: essays research papers

Pain, an acute mental or emotional discomfort, is experienced by everyone many times during the course of his or her lives. This discomfort to a person may be the result of slipping on a patch of ice on the sidewalk, or may be the result of working hard on ones homework. Whatever the cause, precautions can be taken to avoid pain, like wearing a helmet while bicycling, but painful situations pop up all the time. Pain during the coarse of ones life is inevitable. Misery, mental suffering or extreme bodily suffering or discomfort: extreme unhappiness, may not be present for everyone, and is more easily avoided than pain. Misery usually occurs when many things go wrong, or if one major thing in someone’s life goes wrong. These things are meaningful and the misery involved is optional. An example of this could be someone who goes to school, but doesn’t work, fails, and consequently ends up without a job, and feels miserable. This situation could have been avoided, if the person had worked hard at school. This demonstrates the fact that misery can be due to major losses or failures. Therefore even though insignificant causes of pain are inevitable, the things that mean the most can be maintained, and misery is optional. Pain can in some ways be prevented, with the help of preventative measures like wearing a seat belt in a car, a wearing a helmet and pads before going out biking. Even though these measures are applied, there are some things that cannot be controlled, and luck also plays a factor in a person encountering pain. First of all, every time a person goes outside there is a chance that an accident will occur. If someone looses control of their car on black ice, hits a tree and gets injured it really is not their fault. One could say that this could be avoided by not driving in winter, but this isn’t possible. People are active, and as long as they are active there is always an element of risk involved. If one makes dinner they may get burned, but food is needed for the person’s survival. People take risks all the time and pain is somewhat inevitable at different degrees. Some people have a high tolerance for pain and seem to take more risks. Others are more cautious, but the element of pain is always a factor. Generally people are more susceptible to smaller sources of pain, because they take small risks, however people are more careful when confronted with serious pain, like the fact that someone may wear a

Abc Electronic Case Study

ABC Electronics Ltd. – A Wrong Analysis of Consumer Behavior ABC Electronics Ltd. was a company established in 1983 by Mr. Manoj Kumar and over the years had emerged as one of the leaders in the growing segment of the electronics and home appliances market in India. Currently it has a market share of 30% of the home appliances market. Its product strategy has been to offer a wide range, right from mono stereo, two in ones and sophisticated music systems to televisions, refrigerators, washing machines, ovens and microwave ovens.ABC’s marketing strategy also included offering the above products so as to match the needs and budget of the middle and upper middle classes. In 1991, Prasad, son of Mr. Manoj Kumar, took over as the Managing Director of the company. Seeing the intense competition in the post liberalization scenario, Prasad was keen to follow the principle that once you have decided on your target customer, you follow him/her relentlessly with attractive offering s. In 1994, he developed a well focused promotion and distribution strategy. The promotion strategy involved an advertising budget of Rs. 0 crores, a special training program for the sales force and offering freebies and various other sales promotion techniques. In terms of distribution, Prasad selected exclusive showrooms and franchisees to display their wide range of products. The location of the exclusive retail outlets was also selected so as to match the perceptions of the consumers as an â€Å"exclusive showroom† for them. However, even after two years of implementing the new promotion and distribution strategy, the sales of ABC Electronics did not pick up to the extent that the company thought it would.Prasad then directed the marketing manager to conduct a study of other retail outlets to know the trend. The results revealed that there was a change in consumers’ perceptions regarding purchasing consumer durables. There seemed to be a preference for purchasing g oods from multi brand, rather than from single brand outlets. Questions 1. Where do you think Prasad went wrong in his analysis of consumer behavior? 2. Discuss the change in the role of the consumer today, as compared to the consumer five years ago.M/s. Tufleather Ltd. – â€Å" Tufcom Shoes† For the last fifty years, M/s. Tufleather has been in the business of manufacturing and selling leather to companies which make leather shoes and other related products. In the post liberalization period, i. e. , from 1991 onwards, the company was contemplating entering the shoe manufacturing industry, primarily because the Government was giving substantial support to this industry, particularly to firms that were export oriented.With the intention of selling shoes, the company set up its own factory with R & D facilities in Hosur, Tamil Nadu. In 1993, the company’s R & D department developed a material â€Å"Tufcom†, which it claimed had properties of shoe material permeability, strength, flexibility and durability. The company also set up a sub unit to produce shoes with this new material and conducted test marketing to gauge the initial response. The pilot study indicated positive consumer response.Based on the test marketing results, the company set up a large plant with a huge investment and entered into tie ups with reputed shoe manufacturers to buy the new material and make attractive shoe models. They also planned to have an in-house trained team of sales people who would visit the shoe retail outlets and train their sales persons on how to sell shoes. Tufleather also helped the shoe manufacturing companies by providing point of purchase and advertising materials for a nationwide advertising campaign.The company developed a premium pricing strategy for the Tufcom material, based on the consumer perceptual process – the belief that high price is an indicator of high quality. They felt that Tufcom offered quality that was superior to leather in terms of durability and ease of care. After adopting a skimming pricing strategy, the company would later consider penetrating the lower priced shoe market segment. While the first year after the launch of Tufcom shoes showed positive results, sales began to fall drastically after that.Feedback from their sales team indicated that high price buyers did not get motivated by the factors emphasized by Tufleather, namely durability and ease of care. In addition, some complaints were received from buyers of Tufcom shoes that they found the shoes unusually warm. Questions 1. Where do you think the company went wrong in analyzing consumer shoe buying behavior? 2. Do you think the company should identify a new buyer market, namely the lower priced shoe market segment?