MMR Vaccine and Autism free essay sample

Vaccine and Autism There is a lot of controversy surrounding the MMR vaccine and whether or not it causes Autism. One of the main advocates for causation is Andrew Wakefield. He performed a study in 1998 that consisted of 12 children. Such a small sample group alone is enough for this mother to doubt the validity of his study. I may not be a scientist, but I do know that the larger the sample group is, the more valid the results are going to be. According to http://www. thpc. scot. nhs. uk/Health_Protection/MMR/ AW%20claims. htm, Wakefields theory was this: MMR immunisation leads to measles irus becoming colonised in the lining of the bowel; this process causes inflammatory bowel disease and a leaky bowel; this allows harmful peptides or toxins, which wouldnt normally be absorbed to enter the bloodstream, enter the brain and cause autism. And according to his own summary on http:// www. We will write a custom essay sample on MMR Vaccine and Autism or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page thelancet. om/Journals/lancet/article/PllS0140-6736(97)11096-0/abstract; these were his findings: Onset of behavioural symptoms was associated, by the parents, with measles, mumps, and rubella vaccination in eight of the 12 children, with measles infection in one child, and otitis media in another. All 12 children had intestinal abnormalities, ranging from lymphoid nodular hyperplasia to aphthoid ulceration. Histology showed patchy chronic inflammation in the colon in 11 children and reactive ileal lymphoid hyperplasia in seven, but no granulomas. Behavioural disorders included autism (nine), disintegrative psychosis (one), and possible postviral or vaccinal encephalitis (two). There were no focal neurological abnormalities and MRI and EEG tests were normal. Abnormal laboratory results were significantly raised urinary methylmalonic acid compared with agematched controls ow haemoglobin in four children, and a low serum IgA in four children. However, this study has since been retracted and Mr. Wakefield stripped of his medical license. He has been accused of falsifying his findings and the backgrounds (including the fact that 3 were already showing signs of autism before being vaccinated) of the children involved in his study. According to the CDC (http:// www. cdc. gov/vaccinesafety/concerns/autism/) a scientific review by the Institute of Medicine (10M) concluded that the evidence favors rejection of a causal relationship etween thimerosal-containing vaccines and autism. CDC supports the 10M conclusion that there is no relationship between vaccines containing thimerosal and autism rates in children. For a lot of people, the CDC is the final word of expertise on the subject. For others, like actor

How to Do the Barking Dog Chemistry Demonstration

How to Do the Barking Dog Chemistry Demonstration The Barking Dog chemistry demonstration is based on an exothermic reaction between nitrous oxide or nitrogen monoxide and carbon disulfide. Ignition of the mixture in a long tube results in a bright blue chemiluminescent flash, accompanied by a characteristic barking or woofing sound. Materials for the Barking Dog Demonstration Stoppered glass tube containing N2O (nitrous oxide) or NO (nitrogen monoxide or nitric oxide). You can prepare and collect nitrous oxide or nitrogen monoxide yourself.CS2, carbon disulfideLighter or match How to Perform the Barking Dog Demonstration Unstopper the tube of nitrous oxide or nitrogen monoxide to add a few drops of carbon disulfide.Immediately re-stopper the container.Swirl the contents around to mix the nitrogen compound and carbon disulfide.Light a match or lighter. Unstopper the tube and ignite the mixture. You can throw a lit match into the tube or use a long-handled lighter.The flame front will move rapidly, creating a bright blue chemiluminescent flash and a barking or woofing sound. You can re-light the mixture a few times. After the demonstration is performed, you can see sulfur coating the inside of the glass tube. Safety Information This demonstration should be prepared and performed inside a fume hood by a person wearing safety goggles. Carbon disulfide is toxic and has a low flash point. What Is Happening in the Barking Dog Demonstration? When the nitrogen monoxide or nitrous oxide is mixed with carbon disulfide and ignited, a combustion wave travels down the tube. If the tube is long enough you can follow the progression of the wave. The gas ahead of the wavefront is compressed and explodes at a distance determined by the length of the tube (which is why when you re-ignite the mixture, the barking sounds in harmonics). The bright blue light that accompanies the reaction is one of the few examples of a chemiluminescent reaction that occurs in the gas phase. The exothermic decomposition reaction between nitrogen monoxide (oxidizer) and carbon disulfide (fuel) forms nitrogen, carbon monoxide, carbon dioxide, sulfur dioxide and elemental sulfur. 3 NO CS2 → 3/2 N2 CO SO2 1/8 S8 4 NO CS2 → 2 N2 CO2 SO2 1/8 S8 Notes about the Barking Dog Reaction This reaction was performed by Justus von Liebig in 1853 using nitrogen monoxide and carbon disulfide. The demonstration was so well-received that Liebig performed it a second time, although this time there was an explosion (Queen Therese of Bavaria received a minor wound on the cheek). Its possible the nitrogen monoxide in the second demonstration was contaminated with oxygen, to form nitrogen dioxide. There is also a safer alternative to this project that you can do with or without a lab.

The Market for Lemons Case Study Example | Topics and Well Written Essays - 1750 words

The Market for Lemons - Case Study Example Akerlof then says that, although his theory has these very general applications, he will focus on the market for used cars: "The automobile market is used as a finger exercise to illustrate and develop these thoughts. It should be emphasized that this market is chosen for its concreteness and ease in understanding rather than for its importance or realism" (Akerlof, George, 1970) On first reading, it is tempting to interpret "the automobile market" as the market in which real people buy and sell real cars and to think that Akerlof is going to present some kind of case-study. One can see why he might focus on one particular market which is easy to understand, even if that market is not very important on the scale of the economy as a whole. But then what does Akerlof mean when he says that this market is not realistic The object of a case-study may be unrepresentative, but it cannot be unrealistic. To make sense of this passage, we have to recognize that it marks a transition between the real world and the world of models. Akerlof is using the real automobile market as an example. But what he is going to present is not an empirical case study; it is a model of the automobile market. Although it is the real market which may be unimportant, it is the model which may be unrealistic. Akerlof moves straight on to the central section of his paper, section II, entitled "The Model with Automobiles as an Example." The transition from reality to model is made again at the very beginning of this section: The example of used cars captures the essence of the problem. From time to time one hears either mention of or surprise at the large price difference between new cars and those which have just left the showroom. The usual lunch table justification for this phenomenon is the pure joy of owning a "new" car. We offer a different explanation. Suppose (for the sake of clarity rather than realism) that there are just four kinds of cars. There are new cars and used cars. There are good cars and bad cars. (Akerlof, George, 1970) The first four sentences are about an observed property of the real world: there is a large price difference between new cars and almost-new ones. Akerlof suggests that, at least from the viewpoint of the lunch table, this observation is difficult to explain. If we assume that Akerlof takes lunch with other economists, the implication is that economics cannot easily explain it; the "pure joy" hypothesis sounds like an ad hoc stratagem to rescue conventional price theory.