Thursday, December 31, 2015

Why were women not allowed to act in Shakespeare's time?

In Shakespeare's time, gender roles placed far more limitations on women than they do in the Western world today. A woman's life was to be spent as a wife and mother, and even in childhood girls would be expected to help care for their younger siblings and perform household duties. Women who did not follow the plan of marrying young and having lots of babies until they died were considered to be strange and immoral. Women who did not marry at all were sometimes accused of being witches or sex workers-- which they might well have been, in the absence of a husband to pay the rent!


It is important to remember that in Shakespeare's time, performing arts were considered uncouth. To have to "dance for your dinner" was undesirable and typically only done by people of a low class. Women in Shakespeare's time did not act on stage because it would require them to violate a number of social norms. First, to act on stage, a woman would either have to be unmarried or leave her family at home- neither was deemed acceptable. Second, a woman who performed for money would blur the line between sex work and performative arts. To bring a woman on stage would have been social implication that she was available for sex and could be propositioned openly. Even though they came from lower classes, actors wanted their trade to be seen as reputable and thus distanced themselves from work they considered immoral. 


As women were barred from the stage, women's roles were played by younger men and boys whose voices had not yet deepened. Today, some theatre companies or particular runs of plays which want to stay true to the Shakespearean tradition will cast men in women's roles.

Wednesday, December 30, 2015

What imagery is present in Old Major's song about Utopia and is this imagery effective in persuading Old Major's audience? Explain why.

In the first chapter of Animal Farm, Old Major gathers the animals in the barn and gives a rousing speech on equality and the tyranny of man. As part of this speech, he teaches the animals a song called "The Beasts of England" which is immediately popular with his listeners because of a number of strong and provocative images.


Firstly, the song has a strong image of a "golden future time;" a future in which man has been replaced as the ruler of the world. Instead, animals from all parts of the country, including Ireland, are united and free to roam the land. This image of a "golden" era is reinforced by words like "fruitful" and "riches" which emphasise the abundance of produce available to the animals, once Man has been overthrown. This imagery works so well because it is reminiscent of the animal's heaven, a place called Sugarcandy Mountain, which is first mentioned in Chapter Two. 


Secondly, this song uses images of cruelty which are contrasted against ideals of freedom. This is best expressed in the third verse of the song which talks of the removal of rings from the animal's noses and the end of cracking whips. Given the circumstances of life under Mr Jones, the animals recognise and identify with these powerful images of animal cruelty, as soon as they hear the words. In the minds of the animals, then, this image comes to represent their plight and is effective because it gives them hope that Mr. Jones' rule will soon come to an end. 

How many moles are in 8.6 g of CO2?

A mole of a substance contains a molar mass of that substance. The molar mass of a substance is equal to the mass of all the atoms contained in a mole of that substance.


For example, carbon dioxide consists of carbon and oxygen. More specifically, each molecule of carbon dioxide contains 1 atom of carbon and 2 atoms of oxygen. Since, carbon has an atomic mass of 12 g per mole and oxygen has an atomic mass of 16 g per mole, the molar mass of carbon dioxide is 44 g per mole (= 12 + 2 x 16).


That is, one mole of carbon dioxide contains 44 g of carbon dioxide. Here, we have only 8.6 g carbon dioxide. Thus, the number of moles in 8.6 g carbon dioxide are equal to 


8.6 g / 44 g/mole = 0.1955 mole or about 0.2 moles.


Hope this helps.

Tuesday, December 29, 2015

What are the social issues found in The Pearl by John Steinbeck?

The Pearl by John Steinbeck is most definitely a work of social criticism. At the forefront of the story we see The Pearl as a simple parable teaching readers that greed is bad. Greed is the main evil that confronts the town (i.e. the priest, the doctor, the pearl buyers). It is clear that greed corrupts both people in power and lower-class citizens. Socially, this greed then spreads throughout classes and damages even innocent victims.


If we dig deeper into the novella, though, it is clear that Steinbeck had a much bigger agenda. Works of social criticism tend to critique the rules and expectations of a society. In The Pearl Steinbeck challenges the idea that society needs to keep the poor and powerless in their place, thus preserving the wealth and power of the upper class. This system of oppression is highlighted by Kino's plight with the pearl. 


Additionally, we can establish Kino not as the villain (as the parable would have us believe) but instead as a victim of a rigid class structure. The real villain here in this story is the town and its oppressive class system.

Why is Tituba not responsible for the tragedies in Salem?

Although Tituba was in some ways a catalyst for getting some of the young girls in Salem interested in magic and divination, she was not necessarily responsible for the hysteria that pervaded the village. The situation that allowed this to happen was related to a much larger context, and Tituba's role was a relatively minor one. She also confessed and wished to be forgiven for her sins and renounced her dealing with the devil (according to historical documents), showing she was willing to leave behind her pagan religious beliefs (as the villagers saw them) and accept Christianity. It may be she was merely telling the court officials what they wanted to hear in order to escape a harsh sentence. It is not known what her ethnic background was, other than "Indian" as stated in court records, but generally it is assumed she was from Barbados. Her ethnic difference made her an effective scapegoat, since her "otherness" made her stand out, and her status as a slave meant she was vulnerable to accusations. 


But with or without Tituba, Salem was ripe for such an event to occur. In addition to a superstitious belief system that led people to believe that financial ruin, illness, crop failure, impotence and various other problems could be caused by witchcraft, the people of Salem, like other Puritans living in Colonial New England, were living with many domestic and social challenges. Many people were having trouble making ends meet due to the harshness of the winter climate and the lack of resources. There was conflict about religion and leadership in many towns. The tensions surrounding daily life boiled up in some places and helped create an atmosphere where witchcraft accusations could flourish. 

How did World War II affect decolonization?

Decolonization, or the disintegration of the European and American empires, began long before World War II. During the early 20th century, ideas about nationalism and freedom reached developing nations, in part because many of their citizens had lived or traveled to Europe. In addition, the Russian Revolution in 1917 unleashed ideas about the freedom of poor and subjugated people through communism, and these ideas also began to have a global reach. At the end of World War I, the League of Nations promoted the idea of eventual independence for European colonies. The developing world responded to these currents of thought.


In addition, developing nations were proving that they could defeat the western powers. For example, Japan's victory in the Russo-Japanese War of 1904-1905 proved that an Asian country could defeat an empire that was in part European. During World War II, England promised India that it could eventually be independent so that India would stay loyal to Britain (India became independent in 1948). Many Asian countries were conquered by Japan during World War II, and after the war, these countries, such as the Philippines, wanted freedom rather than to return to American or European rule. Europeans also found administering the colonies very costly, and they did not have money to do so after the expense of fighting World War II. While the Cold War slowed the process of decolonization to some degree, this process had already been put into motion. 

Monday, December 28, 2015

In "Lamb to the Slaughter" by Roald Dahl, what does Dahl want the reader to think/feel/understand about the story?

I think one thing that Dahl wants us to feel is the emotional shift that the reader goes through.  When the story begins, the reader can't help but love Mary Maloney.  She's pregnant and very much in love with Patrick.  She's the stereotypical doting wife.  Then to have Patrick so coldly dismiss her gives the reader even more reasons to love Mary and side with her, not Patrick.  But then she kills Patrick, which isn't that big of an emotional shift.  What gets me to strongly reconsider my opinions about Mary are her incredibly calm and calculated steps to get away with the murder.  In some ways, she is just as cold as Patrick.  


I also think about justice and injustice when I read this story.  Did Patrick receive justice?  What about Mary?  Surely not.  She got away with murder, but were her actions justified?  Was she even in her right mind when she hit Patrick?  I think those are all questions that Dahl wants readers to wrestle over.  

What is fibrocystic breast condition?


Causes and Symptoms

Fibrocystic breast change is the most common type of noncancerous breast condition. Its incidence rate in females is estimated to be more than 60 percent. Therefore, although once classified as a disease, it is now considered to be a normal physiologic variant. It occurs more commonly in females between the ages of thirty and fifty. Its cause is hypothesized to be an excess of circulating estrogen.



Female breast development begins at puberty, triggered by an increase in estrogen level. The four main components of the mature female breast are adipose tissue (fat), ducts (milk ducts and collecting ducts), groups of lobules (referred to as lobes), and connective tissue consisting of a matrix of suspensory ligaments (strong fibrous bands). Each breast contains approximately fifteen to twenty lobes that radiate from the nipple area in a spokelike pattern, with the highest distribution being in the upper outer quadrant of each breast. Breast lobe consistency tends to be firm and slightly nodular, but may vary by breast or by individual, while breast fat is almost always soft. Breasts of younger women primarily consist of glandular tissue. Aging changes result in shrinkage of glandular tissue and replacement with fat, which causes the breast to become softer and less well supported.


Symptoms of fibrocystic breast change result from hormone-induced alterations in the stromal (deeper layer) tissue, glands (lobules) and ducts within the breast. Those changes include possible fibrosis (formation of fibrous tissue like that of scar tissue ) and/or formation of cysts, as fluid accumulates inside the glands. Small amounts of accumulated fluid result in microscopic cysts (microcysts); larger amounts of accumulated fluid result in palpable macrocysts that may grow to an inch or more in size. The two major types of breast cysts are type I, characterized by high concentrations of androgen and estrogen conjugates, epidermal growth factor, and potassium and low concentrations of sodium and chloride; and type II, characterized by high concentrations of sodium and chloride and lower concentrations of androgen and estrogen conjugates, epidermal growth factor, and potassium.


Symptoms of fibrocystic breast change include dense and irregular lumpiness in breast tissue, discomfort, dull pain, localized edema (swelling) and feeling of fullness, tenderness, and possible nipple discharge. Symptoms may vary in intensity throughout the menstrual cycle, peak just prior to menstruation, and range from mild to severe. Symptoms and signs of fibrocystic change may remit after menopause because of decreased amounts of glandular tissue in the breast and decreased levels of estrogen and progesterone.




Treatment and Therapy

Treatment is not for the condition itself but rather for the symptoms. For those women who are asymptomatic, no treatment beyond monitoring via breast self-examination is required. For those women who are symptomatic, treatment options range from use of a properly fitting support bra to use of hormone therapy—via oral contraceptives, androgens, or tamoxifen (a drug that blocks estrogen activity)—which has the potential to cause side effects. Cysts may require fine needle aspiration or ultrasonogrphy to determine whether a biopsy is needed.


Anecdotal evidence suggests that avoidance of methylxanthine-containing items such as coffee, tea, chocolate, and certain sodas; reduction in sodium intake; use of vitamin supplements; and/or use of herbal supplements may ameliorate symptoms caused by fibrocystic changes. However, these findings have not been clinically proven.




Perspective and Prospects

The preferred term for fibrocystic breast disease is now “fibrocystic breast changes” or “fibrocystic breast condition.” It may also be referred to as benign breast disease, benign breast lesions, diffuse cystic mastopathy, mammary dysplasia, or nonmalignant breast neoplasms. Cohort studies of risk factors associated with this condition have been conducted for up to thirty years. A family history of fibrocystic breast condition is believed to be the highest risk factor. Consumption of a high-fat diet may be a cofactor. No association has been found between incidence rate of this condition and alcohol consumption or cigarette smoking.


Breast tissue changes as a result of fibrocystic breast condition may make breast examination and mammography interpretation more difficult. However, while presence of type I macrocytes—a fibrocystic change characterized by high concentrations of androgen and estrogen conjugates, epidermal growth factor, and potassium—may be linked to a moderate increase in breast cancer risk, most fibrocystic changes associated with fibrocystic breast condition (fibrosis, microcysts, and type II macrocysts) are not associated with an increased risk of breast cancer.




Bibliography:


Ajao, O. G. “Benign Breast Lesions.” Journal of the National Medical Association 71, no. 9 (1979): 867–868.



Bhimji, Shabir, et al. "Fibrocystic Breast Changes." MedlinePlus, Nov. 5, 2012.



"Breast Diseases." MedlinePlus, May 3, 2013.



Bruzzi P., L. Dogliotti, and C. Naldoni, et al. “Cohort Study of Association of Risk of Breast Cancer with Cyst Type in Women with Gross Cystic Disease of the Breast.” BMJ 314 (1997): 925–928.



Dixon, J. M., A. B. Lumsden, and W. R. Miller. “The Relationship of Cyst Type to Risk Factors for Breast Cancer and the Subsequent Development of Breast Cancer in Patients with Breast Cystic Disease.” European Journal of Cancer and Clinical Oncology 21 (1985): 1047–1050.



"Fibrosis and Simple Cysts." American Cancer Society, Aug. 24, 2012.



Guray, M. Sahin. “Benign Breast Diseases: Classification, Diagnosis, and Management.” Oncologist 11 (2006): 435–449.



Haagensen, C. D., C. Bodian, and D. E. Haagensen, Jr., eds. Breast Carcinoma: Risk and Detection. Philadelphia: W. B. Saunders, 1981.



Hartmann, L. C., T. A. Sellers, M. H. Frost, et al. “Benign Breast Disease and the Risk of Breast Cancer.” New England Journal of Medicine 353 (2005): 229–237.



Kamel, O. W., R. L. Kempson, and M. R. Hendrickson. “In situ Proliferative Epithelial Lesions of the Breast.” Pathology 1 (1992): 65–102.



Miller, W. R., et al. “Using Biological Measurements: Can Patients with Benign Breast Disease Who Are at High Risk for Breast Cancer Be Identified?” Cancer Detection and Prevention 16 Suppl. (1992): 13–20.



Polsdorfer, Ricker, and Andrea Chisholm. "Fibrocystic Disease." Health Library, Sept. 28, 2012.



Santen, R. J., and R. Mansel. “Benign Breast Disorders.” New England Journal of Medicine 353 (2005): 275–285.



Sauter, Edward R., and Mary B. Daly. Breast Cancer Risk Reduction and Early Dectection. New York: Spring, 2010.



Schnitt, S. J., and J. L. Connolly. “Pathology of Benign Breast Disorders.” In Diseases of the Breast, edited by J. R. Harris et al. 4th ed. Philadelphia: Lippincott Williams & Wilkins, 2010.



"Understanding Breast Changes: A Health Guide for Women." National Cancer Institute, Nov. 2, 2012.



Washington C., et al. “Loss of Heterozygosity in Fibrocystic Change of the Breast: Genetic Relationship Between Proliferative Lesions and Associated Carcinomas.” American Journal of Pathology 157, no. 1 (2000): 323–329.

Was there conflict between Sidi and Sadiku throughout the play?

There are several scenes throughout the play that depict conflict between Sidi and Sadiku. When Sadiku first goes to the village to ask if Sidi will marry Baroka, Sidi tells Sadiku to hold her breath because she is not interested. Sidi goes on to explain that she thinks Baroka only wants to marry her because she is famous. Sadiku is both shocked and offended at Sidi's arrogance. Sadiku believes that Lakunle has filled Sidi's head with crazy thoughts and Sadiku threatens to beat Lakunle. Sidi stands up for Lakunle, then begins to boast about her beauty. Sidi then tells Sadiku that the Bale's skin is too old for her and begins to criticize Baroka's aging physique. Sadiku comments that Sidi must be possessed by angry gods, but Sidi continues to reject Baroka's proposal and invitation to his feast. Later on in the novel, after Sidi loses her virginity to Baroka, Sidi runs onto the stage and throws herself to the ground. Sidi looks up at Sadiku and calls her a fool because Sadiku was tricked by Baroka. When Sidi admits that she is not a maid, Sadiku shows no sympathy for her and tells her to cheer up. The audience can tell that Sadiku does not care for Sidi and views her as arrogant, and Sidi feels that Sadiku is stupid for believing Baroka's lie. There is obvious tension between Sidi and Sadiku throughout the play, and the only reason Sadiku seems happy for Sidi is because Sadiku is no longer the Bale's head wife.

Sunday, December 27, 2015

How can you explain what reduced compliance and high alveolar surface tension means to a layperson?

The key to understanding reduced compliance and high alveolar surface tension is to visualize the more general concept of surface tension. Surface tension is a phenomenon that occurs at the boundary of liquid and air. Liquid particles are more dense than air (i.e. they are packed together more tightly), which causes those particles to push in toward each other. At the liquid-air boundary, the effect is analogous to stretching a thin membrane over the liquid. Think about what a glass of water looks like when you carefully fill it above its rim. A small bump of the liquid extends above the rim, which is maintained due to surface tension at the liquid-air boundary. Another way to look at surface tension is when you see a bug skimming the surface of a pond. The bug is denser than the pond liquid, but surface tension at the top of the pond allows the bug to appear as if it is walking on water.


Surfactants can change surface tension characteristics. If you put a drop of soap into the glass of water, that soap makes the surface more slippery (i.e. it reduces surface tension) and you will not see the bump of liquid above the rim. Likewise, with lower surface tension on a pond, the water-walking bug would sink.


Moving now into how surface tension works in our lungs, our alveolar sacs are coated with a thin layer of surfactant liquid. If surface tension is loo low, the sacs are in a state of reduced compliance and they will collapse into themselves. If surface tension is too high, an impenetrable barrier forms between the air in the sacs and blood in the capillaries around the sacs. In both cases, airflow in the lungs is reduced.


Asthma is an example of high alveolar surface tension. The lungs air sacs in this situation are akin to a glass of water that has plastic stretched across its surface. Nothing will pass through that plastic. Reduced or noncompliant lungs will result from low surface tension. With low surface tension, there is no force to hold the air sacs open (or, to extend an analogy, to support a bug on the surface of the water). 

How could a student effectively write Mr. Underwood's editorial about the killing of Tom Robinson in prison?

In Chapter 25 of To Kill a Mockingbird, Mr. Underwood writes what Scout describes as a "bitter" editorial in The Maycomb Tribune about Tom Robinson's death. Not caring about who cancels their advertisements or subscriptions, Mr. Underwood writes that, in Scout's words, "it was a sin to kill cripples... He likened Tom’s death to the senseless slaughter of songbirds by hunters and children" (page numbers vary according to the edition). In other words, Mr. Underwood finds Tom Robinson's death at the hands of prison guards defenseless because, like a songbird, Tom Robinson is harmless. Tom was a decent, moral man who never caused any problems before a white woman unfairly accused him of rape.


If you were writing Mr. Underwood's editorial, you'd have to think whether you agree with him. Was Tom Robinson's death senseless, or were the prison guards right to shoot Tom as he was supposedly trying to escape? Did Tom really pose a threat? Most likely, Tom did not pose a threat, so the guards were wrong to shoot him. You would want to also include the nature of Tom Robinson's trial in your editorial. There is a great deal of evidence that Tom was not guilty, and you might point out the flawed nature of the justice system in Maycomb. In other words, Tom Robinson should've never been in prison in the first place, so his death was particularly senseless. 

Please paraphrase or summarize Wordsworth's poem "Daffodils." Please include an explanation of sound devices and figures of speech used in the poem.

Wordsworth's daffodils poem (often called "I Wandered Lonely as a Cloud," after the first line) is a simple poem that provides a superb example of Romantic literature. Not much happens within the poem itself. The narrator is originally wandering out in the wild in a lonely and dejected state, until he happens upon a field of daffodils. The sight of the cheery flowers improves the speaker's mood considerably. The narrator ends the poem by saying that the memory of those daffodils always cheers him up whenever he finds himself in a sullen mood.


Despite the poem's simple subject matter, Wordsworth employs some complex figurative language to get his message across. The most significant device that Wordsworth uses is metaphor. The poem abounds with examples of metaphor, such as "I wandered lonely as a cloud" (1), and "[Daffodils] Continuous as the stars that shine/ And twinkle in the milky way" (7-8). By using these metaphors, Wordsworth brings the world of nature to life, turning it into a dynamic entity with a personality all its own. He also employs personification to heighten this effect, saying that the flowers were "tossing their heads in sprightly dance" (12). As for sound devices, the poem follows a simple but effective rhyme scheme of ABABCC, thus providing the piece with an easy-to-follow and reliably musical sound. All in all, it's Wordsworth's skilled and creative use of sound and figurative devices that transform the simple experience of appreciating flowers into a monumental milestone of English literature. 

Saturday, December 26, 2015

Find one quote from the novel To Kill a Mockingbird that portrays Jem wanting to meet Boo Radley.

In Chapter 5, Jem and Dill write a note to Boo Radley asking him if he will come outside sometime and tell them what he does inside his house all day. They also mention in their note that they will not hurt him and will buy him ice cream if he comes out. Scout walks outside and sees Jem and Dill plotting how they will get the note to Boo Radley. Scout asks what they are doing, and Jem says,



"We are going to give a note to Boo Radley" (Lee 62).



Scout is horrified, and Jem mentions that they looked yesterday and found a loose shutter on the side of Boo's house that they might be able to drop the note into. Dill then explains to Scout the contents of the note they wrote to Boo Radley. Jem portrays his curiosity and willingness to meet Boo Radley by writing him a letter and attempting to drop the note in Boo's window.

What is emergency treatment?


Emergency Treatment Overview

A person who has overdosed on a drug requires emergency treatment. Oftentimes, this treatment is initiated by friends, family, or coworkers. Emergency rooms (ERs) can be a challenging maze for persons not familiar with them, but some characteristics are common to most ERs.




Triage yields the first ER assessment, determining illness severity. Triage
is a French word meaning “to pick or cull.” Triage nurses record information related to the patient. Any family or friends accompanying the overdosed patient can be particularly helpful at this time by providing information they have about the overdosed patient. Medications, health history, allergies, and any drug paraphernalia found with the overdosed patient can help with diagnosis. The patient’s vital signs are taken and recorded in triage, including his or her pulse, temperature, respiratory rate, and blood pressure.


Illness severity is usually broken into the following categories at triage: critical and immediately life threatening, such as a heart attack or a heroin overdose in which the patient is not breathing well; urgent but not immediately life threatening, such as most cases of abdominal pain or many cases of alcoholic intoxication; and less urgent, or the “walking wounded,” including those with lacerations, coughs, and sore throats.


The emergency treatment of addictions and substance abuse is at first concerned with treating overdoses. After treatment of an overdosed patient and after medical stabilization, secondary care is initiated. Common substance abuse problems resulting in emergency treatment include alcohol intoxication, cocaine abuse, and heroin abuse. The following information outlines what can be expected if confronted with the care of an overdosed person.


A person overdosed on alcohol will often be obtunded (that is, will have a decreased mental status and will show lethargy and stupor). He or she may be vomiting, may lack muscle coordination, or may be passed out (unconscious). Severely intoxicated persons, who sometimes have a blood alcohol content (BAC) level above 0.35 percent and as high as 0.50 percent, should be transported to an ER as soon as possible. Alcohol levels in that high of a range often mean alcohol poisoning. (Legal limits of alcohol intoxication while driving in the United States is 80 milligrams of ethanol per 100 milliliters of blood, or a BAC of 0.08 percent.) Upon arrival at the ER, the alcohol-poisoned person is first assessed in triage.


An obtunded alcohol-intoxicated patient who is still conscious would most likely be assessed as a category two patient. A person overdosed on heroin, unconscious with the pinpoint pupils characteristic of narcotic overdoses, and with a severely depressed respiratory status, would be advanced to the category one or resuscitation section of the ER. Cocaine intoxication can lead to compromised cardiovascular dynamics. In such cases, pupils are dilated (large), breathing rates speed up, blood pressure elevates, and abnormal heart rates and rhythms occur with cocaine use. A person overdosed on cocaine and with a compromised cardiovascular function would be advanced to category one for emergency care and stabilization.




Basic Stabilization

Overdose precautions taken “in the street” do not (and should not) typically include inserting a needle into the heart (as featured in films and on television). Street methods, which should not be used, sometimes include forced milk ingestion in an unconscious, narcotic-overdosed person, ice packing, or the injection of milk or saltwater (saline) solutions. Serious side effects can ensue, including aspiration pneumonia (milk vomited up from the stomach and into the lungs), hypothermia (dangerously low body temperature), blood infections, and cellulitis (skin infections).


Substance abuse overdose is a serious emergency requiring hospital treatment and evaluation. Someone trained in cardiopulmonary resuscitation (CPR) can check for a pulse in the unconscious person and initiate CPR after calling 911 for assistance; any home or street care should first be guided by accessing the emergency health care system. Recent programs have placed naloxone, a drug that treats narcotic overdoses, in the hands of nonmedical personnel so that they can treat life-threatening overdoses in the street. Training programs for this type of treatment exist in urban areas. A doctor-supervised training program organized through the Chicago Recovery Alliance, for example, has dispensed naloxone to drug users in an effort to provide lifesaving narcotic reversal on the streets.




Emergency Care

Initial ER treatment of a nonresponsive patient involves intravenous (IV) line insertion, oxygen administration, and heart monitoring. An IV provides direct access to blood vessels for medication injection and allows intravenous fluid replenishment if needed. Many obtunded overdose patients have depressed respirations, and oxygen applied through a mask or nasal cannula helps deliver oxygen to the brain and body. Cardiac or heart monitoring along with oxygen-saturation measuring devices offer valuable information related to blood transport in the body.


Emergency treatment of narcotic overdoses requires naloxone. Naloxone blocks the opiate receptors in the nervous system and reverses comas and breathing problems caused by opiates like heroin. Naloxone is rapidly effective, usually reversing the coma and respiratory depression within one or two minutes. A glucose solution is often administered intravenously to unresponsive patients to treat the possibility that low blood sugar is causing or contributing to the unconscious state.


Naloxone is helpful for narcotic overdoses, but it does not readily block alcohol poisoning. An alcoholic will be treated with IV fluids to replenish fluids and minerals and with the vitamin thiamine and multivitamins, and he or she will be observed for many hours until the excess alcohol is metabolized by the person’s liver. Generally, a person’s BAC level will drop from 0.20 to 0.10 in about five hours. This rate of metabolism will vary, and alcoholics often metabolize alcohol at a faster rate.


Cocaine overdose often leads to cardiac arrhythmias, requiring cardiac monitoring, analysis of abnormal rates and rhythms, and appropriate interventions to stabilize the heart. These interventions include IV medications or electrical defibrillation and cardioversion.


All of these treatments are subject to ongoing evaluation and reassessment. A category two alcohol-intoxicated patient could progress to a category one patient with no pulse or blood pressure, requiring advanced CPR and intervention. Narcotic overdosed patients may rapidly improve with naloxone treatments but could “crash” from secondary problems caused by the effects of multiple drug ingestions or by underlying heart, lung, kidney, or brain problems.


Emergency treatment is often followed by inpatient hospitalization, depending on the problems and recovery course. Follow-up care with substance abuse treatment centers is necessary to prevent recurrence of these life-threatening overdoses.




Bibliography


Capriccioso, Richard P. “Emergency Rooms.” Magill’s Medical Guide. Ed. Brandon P. Brown, et al. 6th ed. Pasadena: Salem, 2011. Print.



Marx, John. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 7th ed. Philadelphia: Mosby, 2010. Print.



Samet, J. A. “Drug Abuse and Dependence.” Goldman’s Cecil Medicine. Eds. Lee Goldman and Andrew I. Schafer. 24th ed. Philadelphia: Saunders, 2012. Print.



Terry, Don. “A Shot That Saves the Lives of Addicts Is Now in Their Hands.” New York Times. New York Times, 24 July 2010. Web. 6 Mar. 2012.

Friday, December 25, 2015

What is atherosclerosis?


Risk Factors

There are two types of factors that increase an individual’s chance of atherosclerosis: risk factors the individual cannot control and risk factors the individual can control.






The National Heart, Lung, and Blood Institute states that some of the risk factors that cannot be controlled as having a father or brother who developed complications of atherosclerosis before age fifty-five, or having a mother or sister who developed complications of atherosclerosis before age sixty-five; men forty-five years of age or older and women fifty-five or older are also at risk. Men have a greater risk of heart attack than women.


Risk factors that can be controlled include having high levels of low-density lipoprotein (LDL), or “bad” cholesterol, and low levels of high-density lipoprotein (HDL), or “good” cholesterol; having high blood pressure; cigarette smoking; diabetes type I and type II; being overweight or obese; and a lack of physical activity.


Metabolic syndrome is a combination of three out of the following five findings: low HDL cholesterol (also called “good” cholesterol), high triglycerides, elevated blood sugar, elevated blood pressure, and an increased waist circumference (greater than forty inches in men and thirty-five inches in women).




Etiology and Genetics

Multiple environmental and genetic factors play a contributing part in atherosclerosis. Some individuals are genetically predisposed to developing the condition, yet a detailed genetic analysis and prediction of inheritance patterns are not possible, since so many different genes seem to be implicated. A 2012 literature review by I. M. Stylianou, R. C. Bauer, M. P. Reilly, and D. J. Rader, published in Circulation Research, indicated that thirty-four candidate gene loci and hundreds of single-nucleotide polymorphisms may be involved in atherosclerosis in humans.


One gene with a clear association with atherosclerosis is APOE, found on the long arm of chromosome 19 at position 19q13.2. APOE encodes the protein apolipoprotein E, which functions to carry excess cholesterol from the blood to receptors on the surface of cells in the liver. Some mutations in the gene lead to altered protein products that lack the ability to bind to the receptors, resulting in a marked increase in an individual’s blood cholesterol.


Studies using deoxyribonucleic acid (DNA)
microarray analyses have implicated another gene, EGR1
(early growth response gene 1), as a contributor to some cases of atherosclerosis. Found on the long arm of chromosome 5 at 5q23–q31, this gene encodes a protein that is an important part of the body’s vascular repair system. When inappropriately active in coronary arteries, the effect is the slow closure of the arteries, leading to angina and possible starvation of heart muscle. This important discovery opened new avenues of research designed to develop drugs targeted to inhibit EGR1 gene expression.




Symptoms

There are no symptoms in early atherosclerosis. As the arteries become harder and narrower, symptoms may begin to appear. If a clot blocks a blood vessel or a large embolus breaks free, symptoms can occur suddenly.


Symptoms depend on which arteries are affected. For example, coronary (heart) arteries may cause symptoms of heart disease, such as chest pain; arteries in the brain may cause symptoms of a stroke, such as weakness or dizziness; and arteries in the lower extremities may cause pain in the legs or feet and trouble walking.




Screening and Diagnosis

Most patients are diagnosed after they develop symptoms. However, patients can be screened and treated for risk factors.


A patient who has symptoms will be asked questions by his or her doctor; these questions will help to determine which arteries might be affected. The doctor will also need to know a patient’s full medical history, and a physical exam will be conducted. Tests will depend on which arteries may be involved; these tests will be decided based on the patient’s symptoms, physical exam, and/or risk factors.


Many of these tests detect problems with the tissue that is not getting enough blood. Two common tests that directly evaluate the atherosclerotic arteries are angiography and ultrasonography. In angiography, a tube-like instrument is inserted into an artery. Dye is injected into the vessel to help determine the degree of blood flow. When done in the heart, this test is called cardiac catheterization. An ultrasound is a test that uses sound waves to examine the inside of the body. In this case, the test examines the size and shape of arteries.




Treatment and Therapy

An important part of treatment for atherosclerosis is reducing risk factors. Beyond that, treatment depends on the area of the body most affected.


Treatment may include medications, such as drugs to interfere with the formation of blood clots, like aspirin or clopidogrel (Plavix); drugs to control blood pressure, if elevated; drugs to lower cholesterol, if elevated; and drugs that improve the flow of blood through narrowed arteries, such as cilostazol (Pletal) or pentoxifylline (Trental).


Procedures involving a thin tube, called a catheter, can also be used. The catheter is inserted into an artery. Catheter-based procedures are most often done for arteries in the heart; they may be used to treat atherosclerosis elsewhere in the body. These procedures include balloon angioplasty, in which a balloon-tipped catheter is used to press plaque against the walls of the arteries, increasing the amount of space for the blood to flow.



Stents are usually done after angioplasty. In this procedure, a wire mesh tube is placed in a damaged artery; it will support the arterial walls and keep them open.


In an atherectomy, instruments are inserted via a catheter. They are used to cut away and remove plaque so that blood can flow more easily. This procedure is not often performed.


Surgical options include endarterectomy—removal of the lining of an artery obstructed with large plaques. This procedure is often done in the carotid arteries of the neck; these arteries bring blood to the brain.


Arterioplasty can repair an aneurysm; it is usually done with synthetic tissue. Bypass is the creation of an alternate route for blood flow using a separate vessel.




Prevention and Outcomes

There are a number of ways to prevent, as well as reverse, atherosclerosis. They include eating a healthful diet that should be low in saturated fat and cholesterol and rich in whole grains, fruits, and vegetables. Patients should exercise regularly, maintain a healthy weight, and lose weight if they are overweight. They should not smoke; if they smoke, they should quit. Patients should also control their diabetes, if present.


If a doctor recommends it, a patient should take medication to reduce his or her risk factors. This may include medicine for high blood pressure or high cholesterol. Patients should also talk to their doctors about screening tests for atherosclerotic disease of the heart (coronary artery disease) if they have risk factors.




Bibliography


American Association for Clinical Chemistry. "APOE Genotyping, Cardiovascular Disease." Lab Tests Online. Amer. Assn. for Clinical Chemistry, 18 Mar. 2014. Web. 22 July 2014.



Ballantyne, Christie M., James H. O’Keefe, and Antonio M. Gotto. Dyslipidemia and Atherosclerosis Essentials. 4th ed. Sudbury: Jones, 2009. Print.



Beers, Mark H., ed. The Merck Manual of Medical Information. 3rd home ed. Whitehouse Station: Merck Research Laboratories, 2009. Print.



Kohlstadt, Ingrid, ed. Food and Nutrients in Disease Management. 2nd ed. Boca Raton: CRC, 2012. Print.



National Heart, Lung, and Blood Institute. "Atherosclerosis." National Institutes of Health. US Dept. of Health and Human Services, 1 July 2011. Web. 22 July 2014.



Roberts, Robert, Ruth McPherson, and Alexandre F. R. Stewart. “Genetics of Atherosclerosis.” Cardiovascular Genetics and Genomics. Ed. Dan Roden. Hoboken: Wiley-Blackwell, 2009. Print.



Rosenbaum, Laurie. "Atherosclerosis." Health Library. EBSCO, 2 May 2014. Web. 14 July 2014.



Stephenson, Frank H. “Atherosclerosis.” DNA: How the Biotech Revolution Is Changing the Way We Fight Disease. Amherst: Prometheus, 2007. Print.



Stylianou, Ioannis M., Robert C. Bauer, Muredach P. Reilly, and Daniel J. Rader. "Genetic Basis of Atherosclerosis: Insights from Mice and Humans." Circulation Research 110 (2012): 337–55. PDF file.

A rock is projected upward from the surface of the moon, at time t = 0.0 s, with a velocity of 30 m/s. The acceleration due to gravity at the...

A rock launched with an initial speed will move outward from the moon's surface (that is, it will go up). Its motion will be resisted by the gravity of the moon, which will cause deceleration and ultimately the rock will stop and then fall back. The point where the velocity of the rock (during its upward journey) is zero is also its maximum height.


Thus, at the maximum height velocity = 0 m/s.


Initial velocity, u = 30 m/s


final velocity, v = 0 m/s


acceleration, a = 1.62 m/s^2 (in downward direction)


Using the equation of motion, v^2 = u^2 + 2as


we get, 0^2 = 30^2 + 2 x -1.62 x s


or, s = 30^2 / (2 x 1.62) 


solving this equation, we get: s = 277.78 m


Thus, the rock will achieve a maximum height of 277.78 m before falling back to the moon's surface.


Hope this helps. 

Thursday, December 24, 2015

What is anesthesiology?


The History of Anesthesiology

In a modern hospital, the surgical operating room normally is a very quiet place. The anesthesiologist, surgeon, assisting doctors, and nurses perform their duties with little conversation while the patient sleeps. Family members sit quietly in a nearby waiting room until the operation is over. Before the advent of anesthesiology in the 1840s, however, surgery was a thoroughly gruesome experience. Patients might drink some whiskey to numb their senses, and several strong men were recruited to hold them down. Surgeons cut the flesh with a sharp knife and sawed quickly through the bone while patients screamed in agony. The operating room in the hospital was located as far as possible from other patients awaiting surgery so that they would not hear the cries so plainly.



Many kinds of operations were performed before anesthetics were discovered. Among these were the removal of tumors, the opening of abscesses, amputations, the treatment of head wounds, the removal of kidney stones, and cesarean sections and other surgeries during childbirth. The frightful ordeal of “going under the knife,” however, often caused patients to delay surgery until it was almost too late. Also, for the surgeon it was nerve-racking to work without anesthetics, trying to operate while the patient screamed and struggled.


Sir Humphry Davy (1778–1829) was a distinguished British chemist who studied the intoxicating effect of a gas called nitrous oxide. While suffering from the pain of an erupting wisdom tooth, he sought relief by inhaling some of the gas. In 1800, he published a paper suggesting the use of nitrous oxide to relieve pain during surgery. There was no follow-up on his idea, however, and it was forgotten until after anesthesia had been discovered independently in the United States.


The next episode in the history of anesthesiology was the work of Crawford W. Long (1815–78), a small-town doctor in Georgia. In the early nineteenth century, “ether frolics” had become popular, in which young people at a party would inhale ether vapor to give them a high such as from drinking alcohol. One young man was to have surgery on his neck for a tumor. Long was the town druggist as well as the doctor, so he knew that this fellow had purchased ether and enjoyed its effects. Long suggested that he inhale some ether to ready himself for surgery. On March 30, 1842, the tumor was removed with little pain for the patient. It was the first successful surgery under anesthesia.


Unfortunately, Long did not recognize the great significance of what he had done. He did not report the etherization experiment to his colleagues, and it remained relatively unknown. He used ether a few more times in his own surgical practice, one time while amputating the toe of a young slave. Long finally wrote an article for a medical journal in 1849 telling about his pioneering work, three years after anesthesia had been publicly demonstrated and widely adopted by others.


The story of anesthesiology then moved to Hartford, Connecticut, where a young dentist named Horace Wells (1815–48) played a major role. P. T. Barnum, of show business and circus fame, was advertising an entertaining “GRAND EXHIBITION of the effects produced by inhaling NITROUS OXIDE or LAUGHING GAS!” Wells decided to attend. He was one of the volunteers from the audience and “made a spectacle of himself,” according to his wife.


Another volunteer who had inhaled the gas began to shout and stagger around; finally he ran into a bench, banging his shins against it. The audience laughed, but the observant Wells noticed that the man showed no pain, even though his leg was bleeding. This demonstration gave Wells a sudden insight that a person might have a tooth pulled or even a leg amputated and feel no pain while under the influence of the gas.


Wells became so excited by the idea of eliminating pain that he arranged to have some nitrous oxide gas brought to his office on the next day. Then he had a long talk with a young dentist colleague, John Riggs, about the potential risks of trying it out on a patient. Finally, Wells decided to make himself the first test case, if Riggs would be willing to extract one of his wisdom teeth.


On the morning of December 11, 1844, a bag of nitrous oxide gas was delivered by the man who had been in charge of the previous evening’s exhibition. Wells sat in the dental chair and breathed deeply from the gas bag until he seemed to be asleep. Riggs went to work with his long-handled forceps to loosen and finally pull out the tooth, with no outcry from the patient. After a short time, Wells regained consciousness, spit out some blood, and said that he had felt “no more pain than the prick of a pin.”


After this success, Wells immediately set to work on further experiments. He acquired the apparatus and chemicals to make his own nitrous oxide. Within the next month, he used the gas on more than a dozen patients. Other dentists in Hartford heard about the procedure and started using it. By the middle of January 1845, Wells was confident enough to propose a demonstration to a wider audience.


Wells was able to arrange for a demonstration at Massachusetts General Hospital in Boston. While the audience watched, he anesthetized a volunteer patient with gas and extracted his tooth. Unfortunately, the patient groaned at that moment, causing laughter and scornful comments from the onlookers. Wells was viewed as another quack making grandiose claims without evidence. His demonstration had failed, and he returned to Hartford in discouragement. He later commented that he had probably removed the gas bag too soon, before the patient was fully asleep.


It was another dentist, William T. G. Morton (1819–68), who finally provided a convincing demonstration of anesthesia. Morton tried to obtain some nitrous oxide from a druggist, who did not have any on hand and suggested that ether fumes could be substituted. Morton then used ether on several dental patients, with excellent results. In 1846, he obtained permission for a demonstration at the same hospital where Wells had failed two years earlier. Famous Boston surgeon John Warren and a skeptical audience watched as Morton instructed a patient to breathe the ether. When the patient was fully asleep, Warren removed a tumor from his neck. To everyone’s amazement, there was no outcry of pain during the surgery. After the patient awoke, he said that he felt only a slight scratch on his neck. Warren’s words have been recorded for posterity: “Gentlemen, this is no humbug!” Another doctor said, “What we have seen here today will go around the world.”


The result of this dramatic demonstration of October 16, 1846, spread quickly to other hospitals in the United States and Europe. Several hundred surgeries were performed under anesthesia in the next year. In England, John Snow (1813–58) experimented with a different anesthetic, chloroform, and began to use it for women in childbirth. In 1853, Queen Victoria took chloroform from Snow during the delivery of her eighth child. Acceptance of anesthesia, and the science of anesthesiology, by the medical profession and the general public grew rapidly.




Science and Profession

Nitrous oxide, ether, and chloroform were the big three anesthetics for general surgery and dentistry for nearly a hundred years after their discovery. All three were administered by inhalation, but there were differences in safety, reliability, and side effects for the patient.


Wells, the dentist who had unsuccessfully tried to demonstrate nitrous oxide anesthesia in 1844, came to a tragic end in 1848 because of chloroform. He was testing the gas on himself to find out what an appropriate dosage should be. Unfortunately, he became addicted to the feeling of intoxication that it gave him. While under the influence of a chloroform binge, he accosted a woman on the street and was arrested. He committed suicide while in prison.


Nitrous oxide is a nearly odorless gas that must be mixed with oxygen to prevent asphyxiation. Storing the gases in large, leakproof bags was awkward. By comparison, ether and chloroform were much more convenient to use because they are liquids that can be stored in small bottles. The liquid was dripped onto a cloth and held over the patient’s nose. Ether is hazardous, however, because it is flammable, and it also has a disagreeable odor. Chloroform is not flammable but is more difficult to administer because of the danger of heart stoppage.


Anesthesiology was practiced primarily by dentists, eye doctors, chemists, and all types of surgeons for many years. The Mayo Clinic in Rochester, Minnesota, was one of the first hospitals to recognize the need for specialists to administer anesthesia. In 1904, a nurse from Mayo named Alice Magaw gave a talk on what she had learned from eleven thousand procedures performed under anesthesia. Her concluding comment was that “ether kills slowly, giving plenty of warning, but with chloroform there is not even time to say good-by.” Ether takes more time to induce anesthesia, but Magaw asserted that the patient’s life was in less danger than from chloroform.


A Scottish physician, James Y. Simpson, was one of the early advocates of using chloroform for partial anesthesia during childbirth. The woman could breathe the vapor intermittently for several hours as needed without the disagreeable odor of ether. She would remain conscious, but the anesthetic apparently produced a kind of amnesia so that the pain was not fully remembered. Simpson received much public acclaim for his help to women in labor, including a title of nobility. (One humorist of the day suggested a coat-of-arms for Sir Simpson, showing a newborn baby with the inscription, “Does your mother know you’re out?”)


In the 1920s, several new anesthetic gases were created by chemists working closely with medical doctors. The advantages and drawbacks of each new synthesized compound were tested first on animals, then on human volunteers, and finally during surgery. One of the most successful ones was cyclopropane: it was quick acting and nontoxic and could be mixed with oxygen for prolonged operations. Like other organic gases, however, it was explosive under certain conditions and had to be used with appropriate caution.


A major development in 1928 was the invention of the endotracheal tube by Arthur Guedel. A rubber tube was inserted into the mouth and down the trachea (windpipe) to carry the anesthetic gas and oxygen mixture directly to the lungs. The space around the rubber tube had to be sealed in some way in order to prevent blood or other fluid from going down the windpipe. Guedel’s ingenious idea was to surround the tube with a small balloon. When inflated, it effectively closed off the gap between the tube and the trachea wall. He gave a memorable demonstration at a medical meeting using an anesthetized dog with a breathing tube in its throat. After inflating the seal, the dog was submerged under water for several hours and then revived, showing that no water had entered its lungs.


The first local anesthetic was discovered in 1884 by Carl Koller, a young eye doctor in Vienna. He was a colleague of the famous psychoanalyst
Sigmund Freud, and together they had investigated the psychic effects of cocaine. Koller noticed that his tongue became numb from the drug. He had the sudden insight that a drop of cocaine solution might be usable as an anesthetic for eye surgery. He tried it on a frog’s eye, with much success. Following the tradition of other medical pioneers, he then tried it on himself. The cocaine made his eye numb. Koller published a short article, and the news spread quickly. Within three months, other doctors reported successful local anesthesia, using cocaine for dentistry, obstetrics, and many kinds of general surgery.


Chemists investigated the molecular structure of cocaine and were able to develop synthetic substitutes such as novocaine, which was faster and less toxic. Another improvement was to inject local anesthetic under the skin with a hypodermic needle. With this technique, it was possible to block off pain from a whole region of the body by deadening the nerve fibers. A spinal or epidural block is often used to relieve the pain of childbirth or for various abdominal surgeries.


There is another class of anesthetic drugs called barbiturates, which were originally developed for sleeping pills. Any medication that induces sleep automatically becomes a candidate for use as an anesthetic. The most successful barbiturate anesthetic has been sodium pentothal. It is normally administered by injection into a vein in the arm and puts the patient to sleep in a matter of seconds. When the surgery is over, the needle is withdrawn and consciousness returns, with few aftereffects for most people. The anesthesiologist may use sodium pentothal in combination with an inhaled anesthetic if the surgery is expected to be lengthy.




Diagnostic and Treatment Techniques

There are four categories of anesthesia and the type used depends on the procedure. Local anesthesia, such as novocaine, is used to numb a small area of the body and allows the patient to remain awake and alert during a procedure or minor surgery. With conscious or intravenous sedation, the patient is given a mild sedative and pain medication. The patient is relaxed, pain-free, and awake during the procedure, but may not remember it afterward.


Regional anesthesia is applied near nerve clusters to prevent pain in a larger area of the body, such as a limb. Examples of regional anesthesia include epidural anesthesia, spinal anesthesia, and caudal anesthesia. Epidural anesthesia, often administered during childbirth, is injected near the sac of fluid around the spinal cord. Pain is numbed after ten to twenty minutes. A catheter is inserted to allow pain control during the procedure as needed. Spinal anesthesia usually involves a single shot of medicine into the spinal cord fluid, and allows immediate pain relief. Caudal anesthesia is administered via an injection in the tailbone.


General anesthesia affects the entire body and is used for major surgeries. It renders the patient unconscious, immobile, and numb during the procedure. Patients receiving general anesthesia have no memory of the procedure afterward. General anesthesia is either inhaled as a gas or vapor or administered intravenously.


Suppose that a man is scheduled to have some kind of abdominal surgery, such as the repair of a hernia or hemorrhoids or the removal of the appendix, an intestinal blockage, or a cancerous growth. The anesthesiologist would select a sequence of anesthetics that depends primarily on the expected length of the operation and the physical condition of the patient.


About an hour before surgery , the patient receives a shot of medication to produce relaxation and drowsiness. After he is wheeled into the operating room, the anesthesiologist inserts a needle into a vein in the patient’s arm and injects a barbiturate such as sodium pentothal. This drug puts him to sleep very quickly because it is rapidly distributed through the body, but it is not suitable for maintaining anesthesia.


A muscle-paralyzing agent such is now injected, which allows the anesthesiologist to insert an endotracheal tube into the lungs. The tube delivers the general anesthesia, along with oxygen, as a vapor or gas. The seal around the tube must be inflated to prevent fluids from entering the windpipe. The patient is now in a state of surgical anesthesia.


For a difficult surgery, an additional medication may be injected to paralyze the abdominal muscles completely. In this case, the breathing muscles would also become paralyzed, which means that a mechanical respirator would be needed to inflate and deflate the lungs.


The anesthesiologist monitors the patient’s condition with various instruments, such as a stethoscope, blood pressure and temperature sensors, and an electrocardiograph (EKG or ECG) with a continuous display. A catheter may be inserted into a vein to inject drugs or to give a blood transfusion if necessary. When the surgery is completed, the anesthesiologist is responsible for overseeing procedures undertaken in the recovery room as the patient slowly regains consciousness.




Perspective and Prospects

Many modern surgeries would be impossible without anesthesia. Kidney or other organ transplants, skin grafts for a burn victim, or microsurgery for a severed finger all require that the patient remain still for an extended period of time. Anesthesiologists choose from a variety of local and general anesthetics as the individual situations require.


In the emergency room of a hospital, patients are brought in with injuries from industrial, farm, or car accidents. Gunshot and knife wounds, the ingestion of toxic chemicals, or sports injuries often require immediate action to reduce pain and preserve life. Soldiers who are wounded or burned in battle can be given relief from pain because of the available anesthetics. Beyond operating room patients, another category of people who benefit greatly from anesthesia are those who suffer from chronic pain, including that from arthritis, back pain, asthma, brain damage, cancer, and other serious ailments.


A more recent innovation is electric anesthesia, which employs an electric current. It is widely used for animals and is gaining acceptance for humans. A marine biologist can submerge two electrodes into water and cause nearby fish to become rigid and unable to swim. After being netted and tagged, the fish are released with no harmful aftereffects. Veterinarians can use a commercially available device with two electrodes that attach to the nose and tail of a farm animal. Pulses of electricity are applied, causing the animal to remain immobilized until surgery is completed.


The most common human application of electric anesthesia is in dentistry. The metal drill itself can act as an electrode, sending pulses of electric current into the nerve to deaden the sensation of pain. The discomfort of novocaine injections and the possible aftereffects of the drug are avoided. Another application is to provide relief for people with chronic back pain, using a small, battery-powered unit attached to the person’s waist.


Experiments have been done using electricity for total anesthesia, both on animals and on human volunteers. Electrodes are strapped to the front and back of the head. When an appropriate voltage is applied, the subject falls into deep sleep in a short time. When the electricity is turned off, consciousness is regained almost immediately. In one experiment, two dogs underwent “electrosleep” for thirty days with no apparent ill effects. Long-term studies with more subjects are needed to establish this new technology.




Bibliography


"Anesthesia." MedlinePlus. US Natl. Lib. of Medicine, Natl. Inst. of Health., 14 Jan. 2015. Web. 17 Feb. 2015.



"Anesthesia Fact Sheet." National Institute of General Medical Sciences. Natl. Inst. of Health, 17 Nov. 2014. Web. 17 Feb. 2015.



Gregory, George A., ed. Pediatric Anesthesia. 4th ed. New York: Churchill Livingstone, 2002.



Gross, Amy, and Dee Ito. “All About Anesthesia: What Are the Choices When It Comes to Childbirth and Surgery?” Parents Magazine 65 (April, 1990): 213–21.



Liou, Louis S. "Spinal and Epidural Anesthesia." MedlinePlus. US Natl. Lib. of Medicine, Natl. Inst. of Health., 7 May 2013. Web. 17 Feb. 2015.



Longnecker, David E., and Frank L. Murphy. Dripps, Eckenhoff, Vandam Introduction to Anesthesia. 9th ed. Philadelphia: W. B. Saunders, 1997.



Matthes, Kai, et al., eds. Anesthesiology. New York: Oxford University Press, 2013.



Mayo Clinic. "General Anesthesia." Mayo Foundation for Medical Education and Research, January 19, 2013.



MedlinePlus. "Anesthesia." MedlinePlus, August 6, 2013.



Miller, Ronald D., ed. Miller’s Anesthesia. 7th ed. Philadelphia: Churchill Livingstone/Elsevier, 2010.



Palmer, C. M., M. Paech, and R. D’Angelo, eds. Handbook of Obstetric Anesthesia. 6th ed. Oxford, England: Bios Scientific, 2002.



Rushman, G. B., N. J. H. Davies, and R. S. Atkinson. A Short History of Anaesthesia. Oxford, England: Butterworth-Heinemann, 1996.



Sweeney, Frank. The Anesthesia Fact Book: Everything You Need to Know Before Surgery. Cambridge, Mass.: Perseus, 2003.



Wolfe, Richard J. Tarnished Idol: William Thomas Green Morton and the Introduction of Surgical Anesthesia—A Chronicle of the Ether Controversy. San Francisco: Norman, 2000.

What is the point of view in J.M. Barrie's Peter Pan?

The point of view in J.M. Barrie's literary classic Peter Pan is that of the unnamed narrator. Peter Pan is told entirely in the third-person, a conventional story-telling style that is distinct from the epistolary and first-person styles of writing, the latter being particularly common. While it is a story told in the third-person by an omniscient narrator, Barrie's style is to make the narrator more than just an unseen observer; on the contrary, the narrator in Peter Pan is pretty much an integral part of the story, commenting on every aspect of the characters' personalities and idiosyncrasies, including those of the family pet, a large canine that assumes the role of "nurse" to the Darling children. Barrie treats this pet, Nana, as a veritable member of the family, as many pets are in real life. He goes further, however, in ascribing to this large animal the attributes of an actual childcare provider. Describing Nana's role in the Darling household, Barrie notes of this member of the family:



"She had always thought children important, however, and the Darlings had become acquainted with her in Kensington Gardens, where she spent most of her spare time peeping into perambulators, and was much hated by careless nursemaids, whom she followed to their homes and complained of to their mistresses."



While the point of view in Peter Pan is that of the narrator, the perspectives do change accordingly, as the story shifts from the family's home, during which time the parents represent the dominant presence and perspective, to that of Wendy, oldest child among the Darling's three children. Wendy's relationship to Peter, of course, provides the crux of the story, and the interaction between the two provides the most poignant of passages as this young girl and her two brother, John and Michael, travel to Neverland and meet the Lost Boys. In any event, the point of view in Peter Pan is that of the narrator.

What is the relationship between crime and substance abuse?


Background

The precise relationship between substance abuse and crime is difficult to define. First, the cultivation, manufacturing, possession, and sale of illicit drugs are each crimes in their own right. This fact is aligned with numerous studies that have connected the propensity of persons who abuse illicit drugs to commit crimes. Similarly, laws dictating the appropriate distribution and consumption of alcoholic beverages exist throughout the United States. While these statutes themselves are often violated, there exists a well-established parallel between abusive alcohol use and criminal behavior.




It is widely accepted that the behavior of persons impaired by illicit drug and alcohol abuse are prone to erratic tendencies, poor judgment, impulsivity, and violence that lends itself to criminal activity. Repeated abuse of alcohol and drugs also decreases the self-control and inhibitions that distinguish criminals from law-abiding citizens.


Data acquired from the prison population in the United States illustrates that a considerable number of criminals and prison inmates were under the influence of drugs or alcohol, or both, when committing offenses of all kinds. According to a 2009 survey of ten metropolitan areas in the United States by the Office of National Drug Control Policy, the number of criminals who tested positive for at least one controlled substance during their arrest was as high as 82 percent in some locales. The most prevalent drugs of choice for arrestees included marijuana, cocaine, heroin, morphine, and methamphetamine.




Crime and Alcohol Abuse

Motor vehicle violations make up the majority of alcohol-related crimes in the United States. The National Partnership on Alcohol Misuse and Crime (NPAMC) reports that more than 1 million Americans are arrested for driving while intoxicated each year, cases that result in 780,000 criminal convictions. NPAMC findings also note that alcohol-related automobile accidents cost taxpayers more than $100 billion in law enforcement expenses annually. A staggering thirteen thousand people die in drunk-driving-related accidents in the United States each year.


While decades of public interest campaigns led by national law enforcement agencies like the National Highway Traffic Safety Administration (NHTSA) and nonprofit organizations such as Mothers Against Drunk Driving (MADD) and the DUI Foundation have kept the dangers of drunk driving in the public eye, alcohol abuse is also ubiquitous in a wide variety of non-vehicle-related crimes. Domestic violence, underage drinking, and assault are the most frequently occurring non-vehicle-related but alcohol-related crimes in the United States.


While research has uncovered a recurring coexistence between domestic violence and alcohol abuse, not all domestic abusers are alcoholics and not all alcoholics are domestic abusers. A contrary rationale is that while alcohol abuse is regularly a contributing factor in many acts of domestic violence, there also are cases in which alcohol abuse is used as an excuse or an avoidance of accountability by its perpetrators.


There is less scholarly gray area between alcohol use and criminal behavior by underage people. Consumption of alcohol by persons younger than age twenty-one years is itself a commonly perpetrated crime. According to the Centers for Disease Control and Prevention (CDC), underage drinkers consume 11 percent of all the alcohol consumed in the United States each year, despite the illegality of doing so. CDC data also indicate that underage alcohol abuse leads to higher rates of school absence and reckless sexual behavior, and to brain development and memory problems.


Like their adult counterparts, abusive underage drinkers also have a higher propensity to violate laws against drunk driving and to engage in or be victimized by physical assault. The risk of criminal behavior appears to follow underage drinkers into adulthood, according to a 2011 study by the University of Miami that linked abusive underage alcohol consumption with a greater probability of committing property crimes like theft or predatory crimes like assault later in adulthood.


A 2008 report by the Pew Center on the States reported that more than 5 million incarcerated adults were drinking at the time of committing their offense, a group that constitutes 36 percent of the entire US prison population. The research also showed trends indicating that the more violent a crime, the more likely alcohol was involved.




Crime and Drug Abuse

Drug-related offenses are broken down into three categories by the National Institute on Drug Abuse (NIDA): drug possession and sales, offenses committed to support preexisting drug abuse, and drug-related involvement in criminal activities not related to drugs. In 2011, thirty-one thousand people were arrested in the United States on federal drug charges. The US Drug Enforcement Administration (DEA) arrests more than twenty-six thousand people for possession each year, and has done so every year since 1986.


A majority of illicit drug abusers rely on petty crimes to support their habit. These crimes range from petty theft to burglary to grand theft auto. Data from the US Bureau of Justice Statistics (2002) indicate that one-quarter of convicted property and drug offenders commit their crimes to get money for drugs. NIDA research also ties drug use to several other felony convictions, including money laundering, grand theft, and counterfeiting.


While a majority of drug-related crimes can be attributed to the illegality of drugs themselves, research shows that a majority of criminal acts are carried out by persons acting under the influence of or in the pursuit of many types of illicit drugs. That said, the relationship between drugs and crime remains extremely difficult to determine from a research perspective and remains a topic of debate among criminologists and sociologists.




Youth-Oriented Prevention

Federal, state, and local law enforcement agencies have developed numerous systems and processes aimed at reducing the appeal of drug use in hopes of simultaneously halting the various criminal activities that accompany that use. Aimed largely at school-age children and young adults, the agencies’ primary goals have been to prevent persons from entering into the culture of drugs. These programs, which involve coursework and demonstrations of the negative aspects of drug use, have met with varying degrees of success.



The Drug Abuse Resistance Education program (D.A.R.E.) is an example of a failed nationwide effort to curtail drug use and violence. Founded in 1983 by former Los Angeles Police Department chief Daryl Gates, the program was widely utilized in public schools in the United States to explicitly educate young people on the dangers of drug use and activity through lecture-style lessons, drug identification demonstrations, and attempts at building trusting relationships with local police officers through in-school interactions.


By the late 1990s research began to show that the D.A.R.E. program not only was ineffective in decreasing drug use in the majority of communities in which it was utilized but also contributed to a rise in alcohol and drug use among its participants. Evaluation studies demonstrating the program’s ineffectiveness were made by several federal agencies, including the US Office of the Surgeon General and US Department of Education (DE). The program’s widespread reputation for ineffectiveness led the DE to prohibit schools from utilizing federal funds for the program in 1998.


New strategies fostered by the National Youth Anti-Drug Media Campaign in online campaigns, such as TheAntiDrug.com and AboveTheInfluence.com, detract from the communal, schoolroom-oriented strategies of previous programs like D.A.R.E.. The AntiDrug.com program emphasizes positive parental influence as a crucial dissuasion from the temptations of drug-related activity, while AbovetheInfluence.com seeks to tear down the status of illegal drug use as a popular counterculture.




Bibliography


"Alcohol, Drugs and Crime." National Council on Alcoholism and Drug Dependence. NCADD, 27 June 2015. Web. 29 Oct. 2015.



Andrews, D. A. The Psychology of Criminal Conduct. Cincinnati: Anderson, 2010. Print.



Belenko, Steven, and Cassia Spohn. Drugs, Crime, and Justice. Thousand Oaks: Sage, 2015. Print.



Galanter, Mark, ed. Alcoholism and Violence: Epidemiology, Neurobiology, Psychology, Family Issues. Recent Developments in Alcoholism 13. New York: Springer, 1997. Print.



Galvin, Emily V. "How Treatment Courts Can Reduce Crime." Atlantic. Atlantic Monthly, 29 Sept. 2015. Web. 29 Oct. 2015.



Hammersley, Richard. Drugs and Crime. London: Polity, 2008. Print.



Hanson, Glen, Peter J. Venturelli, and Annette E. Fleckenstein. Drugs and Society. 11th ed. Sudbury: Jones, 2012. Print.



US Department of Justice. “The Systems Approach to Crime and Drug Prevention: A Path to Community Policing.” Bulletin—Bureau of Justice Assistance 1.2 (Sept. 1993). PDF file.

Wednesday, December 23, 2015

What is bone grafting?


Indications and Procedures

Ideally, the grafting procedure involves the transfer of bone tissue from one site to another on the same individual, which is termed an autogenous graft. This method eliminates the chance of rejection, allowing the transplantation of entire functional units of tissue: arteries, veins, and even nerves, as when a toe is used to replace a finger or thumb (toe-digital transfer). Autogenous rib or fibula grafts may be utilized for the reconstruction of the face or extremities.



Bone grafts are often used in situations in which a bone fracture is not healing properly. A fracture that fails to heal in the usual time is considered to be a delayed union. Cancellous material from the bone (the spongy inner material), usually obtained from the iliac crest of the pelvis or from the ends of the long bones, is placed around the site. The fracture must then be immobilized for several months, allowing the grafted material to infiltrate and repair the fracture.




Uses and Complications

The grafting of bone tissue is carried out to correct a bone defect, to provide support tissue in the case of a severe fracture, or to encourage the growth of new bone. The source of the skeletal defect may be congenital malformation, disease, or trauma. For example, reconstruction may be necessary following cancer
surgery, particularly for the jaw or bones elsewhere in the face.


If the autogenous bone supply is inadequate to fill the need, allogeneic bone grafts, the transplantation of bone from an individual other than an identical twin, may be necessary. Such foreign tissue is more likely to undergo rejection, reducing the chance of a successful procedure; the more closely the tissues of the two persons are matched, the less likely rejection will be a problem.


If the graft is able to vascularize quickly and to synthesize new tissue, the procedure is likely to be successful. The graft itself may provide structural support, or it may gradually be replaced by new bone at that site, completing the healing process.




Bibliography


Aho, OM. "The mechanism of action of induced membranes in bone repair." Journal of Bone and Joint Surgery. 95, 7. (April 2013): 597–604.



Bentley, George, and Robert B. Greer, eds. Orthopaedics. 4th ed. Oxford, England: Linacre House, 1993.



Callaghan, John J., Aaron Rosenberg, and Harry E. Rubash, eds. The Adult Hip. 2d ed. Philadelphia: Lippincott Williams & Wilkins, 2007.



Doherty, Gerard M., and Lawrence W. Way, eds. Current Surgical Diagnosis and Treatment. 12th ed. New York: Lange Medical Books/McGraw-Hill, 2006.



Dowthwaite, SA. "Comparison of fibular and scapular osseous free flaps for oromandibular reconstruction: a patient-centered approach to flap selection." JAMA Otolaryngol Head Neck Surgery. 139, 3. (March 2013): 285–292.



Eiff, M. Patrice, Robert L. Hatch, and Walter L. Calmbach. Fracture Management for Primary Care. 2d ed. Philadelphia: W. B. Saunders, 2003.



Lindholm, T. Sam. Advances in Skeletal Reconstruction Using Bone Morphogenetic Proteins. London: World Scientific, 2002.



Tapley, Donald F., et al., eds. The Columbia University College of Physicians and Surgeons Complete Home Medical Guide. Rev. 3d ed. New York: Crown, 1995.



Tierney, Lawrence M., Stephen J. McPhee, and Maxine A. Papadakis, eds. Current Medical Diagnosis and Treatment 2007. New York: McGraw-Hill Medical, 2006.



Wood, Debra. "Bone graft." Health Library, December 21, 2011.

How does Scout end up in the yard in front of the Radley house?

Scout, Jem, and Dill are playing in the street in front their house with an old tire.  They take turns getting inside the tire and rolling down the street.  When it’s Scout’s turn, Jem gives the tire a big push and the tire rolls into the Radley yard and ends up resting against the porch.  Scout is too dizzy to get up and run, so Jem courageously runs into the yard to rescue her from the Radley’s overgrown, weed-filled yard.   They run back home, and Scout remembers that she heard a laugh come from the Radley house when she was stuck in the tire.  This episode sets the scene for how the children feel about the reclusive Boo Radley, but it also gives us, the readers, a clue that perhaps Boo isn’t the spooky character the children think he is.  Boo laughing at the children’s adventures in the tire shows that he is perhaps harmless and enjoys watching the children play.  It is our first look at Boo Radley and foreshadows the continued interest he has in the welfare of Scout and Jem.

Tuesday, December 22, 2015

How would you critically analyze Pygmalion by George Bernard Shaw from a gender perspective?

Pygmalion by George Bernard Shaw has a plot derived from the classical myth concerning Pygmalion and Galatea, in which the sculptor, Pygmalion, fashioned Galatea, the perfect women, and then Aphrodite gave the sculpture life. In Shaw's retelling of the story, Professor Higgins tries to shape Eliza Doolittle into the perfect aristocratic woman, who can pass for a Duchess at a party.


Shaw, however, rejects the model of woman simply as a passive object shaped by the male will. Eliza Doolittle is a woman with a mind of her own and while she learns manners and style of speech from Higgins, she refuses to be controlled by him. In fact, among the two most effective and strong-willed characters of the play are Eliza and Mrs. Higgins.


Eliza rejects the role of a passive object to be formed by Higgins and instead chooses to marry the weak-willed and amiable Freddy. Shaw sees that strength of character can be found in both men and women equally, and he argues in the Afterword that romantic pairings, rather than being dominated by males, are balanced, with strong characters marrying weaker ones, irrespective of gender:



Eliza has no use for the foolish romantic tradition that all women love to be mastered, if not actually bullied and beaten. ...  [S]trong people, masculine or feminine, not only do not marry stronger people, but ... seek for every other quality in a partner than strength.


What do the archaeological artifacts found in the summer of 2009 reveal about Anglo-Saxon England?

In July 2009, the largest hoard of Anglo-Saxon gold was found in a field in Staffordshire (once part of the Anglo-Saxon kingdom of Mercia). This find is not only significant because of its size (there are over 3500 pieces), but also because of its implications for our historical understanding of Mercia. Previously, it was widely-accepted among historians that Mercia lacked any significant political power compared to other English kingdoms, like Wessex. This find, however, contradicts this view and suggests the reverse is true: the Mercians possessed vast amounts of wealth and traded with merchants across the world.


Additionally, the discovery of this treasure also validates the world portrayed in the epic poem Beowulf. As the curator Gareth Williams has argued, this discovery suggests the poem may be inspired by Mercian warriors, who were evidently some of the wealthiest and most prestigious in England. (See the two reference links provided.)

Monday, December 21, 2015

In Paradise Lost by Milton, what characteristics does Satan have that make him a hero? How does Milton's Satan compare to Beowulf as a hero?

First, we should distinguish between two terms, "hero" and "protagonist." A protagonist is the most important character in a story but can be admirable or despicable or sympathetic or abhorrent. A hero is a protagonist with some type of greatness beyond that of the ordinary mortal, with whom we generally sympathize. Satan's role in Paradise Lost is complicated, not precisely that of a hero, although sharing some characteristics of certain heroic types. Blake and Shelley, who themselves were strongly anti-Christian, interpreted Satan as the hero of the poem, but most critics see their readings as based more in their own ideological concerns than justified by the text. Scholars have debated the question of who counts as a hero in Paradise Lost and the general consensus is that there is no classical heroic figure, but that certain heroic elements can be found in the Son of God, Adam, and Satan.


Milton was a Puritan, a devout Christian espousing a strongly Calvinist form of Protestantism. There is no evidence that Milton himself admired Satan or himself rebelled against God (his other writings suggest deep and sincere piety). There is, however, a literary problem with making God a hero. What makes a narrative interesting is a plot structure in which there is a genuine conflict and normally some sort of obstacle for the protagonist to overcome. Since God is omnipotent, omniscient, and incapable of suffering, God's very perfection as a deity makes him a very dull protagonist indeed; while the Son can be a hero because he will eventually struggle and suffer, and Adam is a mortal who suffers, God the Father cannot be a hero.


Satan as a protagonist captures the imagination in the same way as some of the evil tragic heroes such as Clytemnestra and Medea or Shakespeare's Macbeth. He does not resemble an epic hero such as Beowulf at all, because he is not a force for good or supporter of legitimate authority. While he shares the heroic characteristics of power and strength of body, will, and intellect, he is, within the worldview of the poem, completely and irredeemably fallen. Like many villains, he does tend to get the best lines of the poem and is a character most readers find appealing, but more in the style of a seductive villain than a hero.

What is epistasis?


Definition and History

The term “epistasis” is of Greek and Latin origin, meaning “to stand upon” or “stoppage.” The term was originally used by geneticist William Bateson
at the beginning of the twentieth century to define genes that mask the expression of other genes. The gene at the initial location (locus) is termed the epistatic gene. The genes at the other loci are “hypostatic” to the initial gene. In its strictest sense, epistasis describes a nonreciprocal interaction between two or more genes, such that one gene modifies, suppresses, or otherwise influences the expression of another gene affecting the same phenotypic (physical) character or process. By this definition, simple additive effects of genes affecting a single phenotypic character or process would not be considered an epistatic interaction. Similarly, interactions between alternative forms (alleles) of a single gene are governed by dominance effects and are not epistatic. Epistatic effects are interlocus interactions. Therefore, in terms of the total genetic contribution to phenotype, three factors are involved: dominance effects, additive effects, and epistatic effects. The analysis of epistatic effects can suggest ways in which the action of genes can control a phenotype and thus supply a more complete understanding of the influence of genotype on phenotype.










A gene can influence the expression of other genes in many different ways. One result of multiple genes is that more phenotypic classes can result than can be explained by the action of a single pair of alleles. The initial evidence for this phenomenon came out of the work of Bateson and British geneticist Reginald C. Punnett during their investigations on the inheritance of comb shape in domesticated chickens. The leghorn breed has a “single” comb, brahmas have “pea” combs, and wyandottes have “rose” combs. Crosses between brahmas and wyandottes have “walnut” combs. Intercrosses among walnut types show four different types of F2 (second-generation) progeny, in the ratio 9 walnut:3 rose:3 pea:1 single. This ratio of phenotypes is consistent with the classical F2 ratio for dihybrid inheritance. The corresponding ratio of genotypes, therefore, would be 9 A_ B_:3 A_ bb:3 aa B_:1 aa bb, respectively. (The underscore is used to indicate that the second gene can be either dominant or recessive; for example, A_ means that both AA and Aa will result in the same phenotype.) In this example, one can recognize that two independently assorting genes can affect a single trait. If two gene pairs are acting epistatically, however, the expected 9:3:3:1 ratio of phenotypes is altered in some fashion. Thus, although the preceding example involves interactions between two loci, it is not considered a case of epistasis, because the phenotype ratio is a classic Mendelian ratio for a dihybrid cross. Five basic examples of two-gene epistatic interactions can be described: complementary, modifying, inhibiting, masking, and duplicate gene action.




Complementary Gene Action

For complementary gene action, a dominant allele of two genes is required to produce a single effect. An example of this form of epistasis again comes from the observations of Bateson and Punnett of flower color in crosses between two white-flowered varieties of sweet peas. In their investigation, crosses between these two varieties produced an unexpected result: all the F1 (first-generation) progeny had purple flowers. When the F1 individuals were allowed to self-fertilize and produce the F2 generation, a phenotypic ratio of nine purple-flowered to seven white-flowered individuals resulted. Their hypothesis for this ratio was that a homozygous recessive genotype for either gene (or both) resulted in the lack of flower pigmentation. A simple model to explain the biochemical basis for this type of flower pigmentation is a two-step process, each step controlled by a separate gene and each gene having a recessive allele that eliminates pigment formation. Given this explanation, each parent must have had complementary genotypes (AA bb and aa BB), and thus both had white flowers. Crosses between these two parents would produce double heterozygotes (Aa Bb) with purple flowers. In the F2 generation, 9/16 would have the genotype A_ B_ and would have purple flowers. The remaining 7/16 would be homozygous recessive for at least one of the two genes and, therefore, would have white flowers. In summary, the phenotypic ratio of the F2 generation would be 9:7.




Modifying Gene Action

The term “modifying gene action” is used to describe a situation whereby one gene produces an effect only in the presence of a dominant allele of a second gene at another locus. An example of this type of epistasis is aleurone color in corn. The aleurone is the outer cell layer of the endosperm (food-storage tissue) of the grain. In this system, a dominant gene (P_) produces a purple aleurone layer only in the presence of a gene for a red aleurone (R_) but expresses no effect in the absence of the second gene in its dominant form. Thus, the corresponding F2 phenotypic ratio is 9 purple:3 red:4 colorless. The individuals without aleurone pigmentation would, therefore, be of the genotype P_ rr (3/16) or pp rr (1/16). Again, a two-step biochemical pathway for pigmentation can be used to explain this ratio; however, in this example, the product of the second gene (R) acts first in the biochemical pathway and allows for the production of red pigmentation and any further modifications to that pigmentation. Thus, the phenotypic ratio of the F2 generation would be 9:3:4.




Inhibiting Gene Action

Inhibiting action occurs when one gene acts as an inhibitor of the expression of another gene. In this example, the first gene allows the phenotypic expression of a gene, while the other gene inhibits it. Using a previous example (the gene R for red aleurone color in corn seeds), the dominant form of the first gene R does not produce its effect in the presence of the dominant form of the inhibitor gene I. In other words, the genotype R_ i_ results in a phenotype of red aleurone (3/16), while all other genotypes result in the colorless phenotype (12/16). Thus gene R is inhibited in its expression by the expression of gene I. The F2 phenotypic ratio would be 13:3. This ratio, unlike the previous two examples, includes only two phenotypic classes and highlights a complicating factor in determining whether one or two genes may be influencing a given trait. A 13:3 ratio is close to a 3:1 ratio (the ratio expected for the F2 generation of a monohybrid cross). Thus it emphasizes the need to look at an F2 population of sufficient size to discount the possibility of a single gene phenomenon over an inhibiting epistatic gene interaction.




Masking Gene Action

Masking gene action, a form of modifying gene action, results when one gene is the primary determinant of the phenotype of the offspring. An example of this phenomenon is fruit color in summer squash. In this example, the F2 ratio is 12:3:1, indicating that the first gene in its dominant form results in the first phenotype (white fruit); thus this gene is the primary determinant of the phenotype. If the first gene is in its recessive form and the second gene is in its dominant form, the fruit will be yellow. The fruit will be green at maturity only when both genes are in their recessive form (1/16 of the F2 population).




Duplicate Gene Interaction

Duplicate gene interaction occurs when two different genes have the same final result in terms of their observable influence on phenotype. This situation is different from additive gene action in that either gene may substitute for the other in the expression of the final phenotype of the individual. It may be argued that duplicate gene action is not a form of epistasis, since there may be no interaction between genes (if the two genes code for the same protein product), but this situation may be an example of gene interaction when two genes code for similar protein products involved in the same biochemical pathway and their combined interaction determines the final phenotype of the individual. An example of this type of epistasis is illustrated by seed-capsule shape in the herb shepherd’s purse. In this example, either gene in its dominant form will contribute to the final phenotype of the individual (triangular shape). If both genes are in their recessive form, the seed capsule has an ovoid shape. Thus, the phenotypic ratio of the F2 generation is 15:1.




Impact and Applications

Nonallelic gene interactions have considerable influence on the overall functioning of an individual. In other words, the genome (the entire genetic makeup of an organism) determines the final fitness of an individual, not only as a sum total of individual genes (additive effects) or by the interaction between different forms of a gene (dominance effects) but also by the interaction between different genes (intragenomic or epistatic effects). This situation is something akin to a chorus: great choruses not only have singularly fine voices but also perform magnificently as finely tuned and coordinated units. Knowledge of what contributes to a superior genome would, therefore, lead to a fuller understanding of the inheritance of quantitative characters and more directed approaches to genetic improvement. For example, most economically important characteristics of agricultural species (such as yield, pest and disease resistance, and stress tolerance) are quantitatively inherited, the net result of many genes and their interactions. Thus an understanding of the combining ability of genes and their influence on the final appearance of domesticated breeds and crop varieties should lead to more efficient genetic improvement schemes. In addition, it is thought that many important human diseases are inherited as a complex interplay among many genes. Similarly, an understanding of genomic functioning should lead to improved screening or therapies.




Key Terms




allele


:

an alternate form of a gene at a particular locus; a single locus can possess two alleles




dihybrid cross

:

a cross between parents that involve two specified genes, or loci




F1


:

first filial generation, or the progeny resulting from the first cross in a series




F2


:

second filial generation, or the progeny resulting from the cross of the F1 generation




locus (

:

pl. loci) a more precise word for gene; in diploid organisms, each locus has two alleles





Bibliography


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Jain, Kavita, and Apoorva Nagar. "Fixation of Mutators in Asexual Populations: The Role of Genetic Drift and Epistasis." Evolution 67.4 (2013): 1143–54. Print.



Mackay, Trudy F. C. "Epistasis and Quantitative Traits: Using Model Organisms to Study Gene-Gene Interactions." Nature Reviews Genetics 15.1 (2014): 22–33. Print.



Pang, Xiaoming, et al. "A Statistical Procedure to Map High-Order Epistasis for Complex Traits." Briefings in Bioinformatics 14.3 (2013): 302–14. Print.



Russell, Peter J. Fundamentals of Genetics. 2nd ed. San Francisco: Benjamin, 2000. Print.



Snustad, D. Peter, and Michael J. Simmons. Principles of Genetics. 6th ed. Hoboken: Wiley, 2012. Print.



Wan, Xiang, et al. "The Complete Compositional Epistasis Detection in Genome-Wide Association Studies." BMC Genetics 14.7 (2013): 1–11. Web. 22 July 2014.



Wolf, Jason B., Edmund D. Brodie III, and Michael J. Wade, eds. Epistasis and the Evolutionary Process. New York: Oxford UP, 2000. Print.



Wood, Stacey J., and Alison A. Motsinger-Reif. “Epistasis: Understanding and Evaluating the Phenomenon in Human Genetics Disease Mapping.” Genetic Predisposition to Disease. Ed. Sara L. Torres and Marta S. Marin. New York: Nova, 2008. 195–213. Print.

How does the choice of details set the tone of the sermon?

Edwards is remembered for his choice of details, particularly in this classic sermon. His goal was not to tell people about his beliefs; he ...