In "Araby" by James Joyce, what does Mangan's sister do to make a trip to the bazaar so important to the narrator?

Really, the only thing Mangan's sister does to make going to the bazaar so important to the narrator is to speak to him about it.  She had never actually spoken to the narrator before, and so, when "At last she spoke to [him]," he becomes confused and flustered.  She tells him that it will be a "splendid bazaar" and that "she would love to go"; however, she cannot because she'll be on a retreat with her convent school.  This is enough.  Mangan's sister has spoken to the narrator, and upon this subject, expressing her desire to go to the Araby bazaar and her regret that she cannot.  He seems to imagine this as some kind of quest: he can go in her place and bring her something that will make her happy, and this will make him happy.  In the days between his vow and the bazaar, the narrator finds that he cannot even concentrate on "the serious work of life" because it now seems like "child's play" in comparison to the thing that he desires. 

What transforms the balcony scene into a great moment of poignancy in Shakespeare's Romeo and Juliet?

It would be difficult to overestimate the impact of this particular scene upon dramatic literature, and upon the idea and image of love and romance. The language is beautifully crafted and the imagery sets the tone for the play's theme of the "star-cross'd lovers" who are destined to be together, yet whose situations tragically keep them apart.

Romeo's comparing Juliet to the rising sun, and her description of his name as her enemy, are both expressive of these major themes in the play. The sun and moon imagery the lovers use to describe and refer to one another throughout the play is introduced here. "Arise fair sun and kill the envious moon that is already sick and pale with grief": here Romeo compares Juliet's beauty to the sun and portrays her as more beautiful than the moon. He then continues "It is my lady; oh it is my love! Oh, that she knew she were!" His love and longing is laid bare here, contributing to the scene's poignancy.

We also hear of Juliet's deep love of Romeo despite having just met him, and she suggests she would marry him so that their names will no longer be at odds because of the family feud: "Be but sworn my love and I'll no longer be a Capulet." This also hints at the tendency of these lovers to see themselves reflected in the other, and the sun-moon and day-night imagery also reinforces this theme of the yin-yang, male-female opposites that describe the union of love.

When Romeo finally leaves, Juliet says "Parting is such sweet sorrow," and this foreshadows the moment when Romeo believes she is dead and decides to kill himself rather than live without her. This hint of what is to come also adds poignancy to the scene.

What is the tone and atmosphere during Act III, Scene 1 of Romeo and Juliet?

The tone of a piece of literature is the attitude the author takes toward the audience, a subject or a character. The mood or atmosphere is the feeling created in the reader by the scene or passage. Act III, Scene 1 of Shakespeare's Romeo and Juliet is considered the turning point of the play. It begins the descent toward death and suicide of five of the main characters.

The tone throughout this scene is displayed in the passion of the principal characters. Benvolio is anxious and concerned. Mercutio, on the other hand, displays his typical arrogance and biting humor. Later, he will become bitter and cursing in his tone as he dies after the fight with Tybalt. Tybalt is angry and belligerent. Romeo, who at first is cheerful (he has just married Juliet), later becomes intense and driven.

The mood or atmosphere can be found in the words of Benvolio and Mercutio. The very first lines spoken by Benvolio suggest suspense and they put the audience on the edge of their seats. His warning to Mercutio to get off the street incites a mood of anticipation:

I pray thee, good Mercutio, let’s retire.
The day is hot, the Capels are abroad,
And if we meet we shall not ’scape a brawl,
For now, these hot days, is the mad blood stirring.

This anticipation is suspended for a time with Mercutio's  absurd rant about Benvolio being a fighter. The mood soon turns suspenseful again as Tybalt enters the scene and he and Mercutio banter back and forth. Finally, the mood abruptly turns violent as Mercutio, enraged at Romeo's seeming cowardice, challenges Tybalt:

O calm, dishonorable, vile submission!
Alla stoccato carries it away. [He draws.]
Tybalt, you ratcatcher, will you walk?

This violent mood continues as Romeo realizes his acquiescence toward Tybalt has caused Mercutio's death. When Tybalt returns, the fighting continues and Tybalt is killed. The last part of the scene takes on a mood of tension as Lady Capulet lies about the fighting and calls for the death of Romeo. This tension, verging on more suspense, is only increased as the Prince sentences Romeo to exile. The audience is now anxious to see how the tragedy will play out.

Which body parts are used for locomotion in amoeba?

An amoeba is a single celled protozoa made up of a cellular fluid called cytoplasm. The cytoplasm can be divided into two parts; the ectoplasm, a thin outer layer which acts as its membrane, and the endoplasm, a more watery inner part which contains organelles such as the nuclei.

Amoeba derives its name from its ability to move by continuously changing its body shape. It does this by forming pseudopods, which are temporary extensions into which its body flows. They are therefore regarded as false feet.

When the pseudopod is projected outwards along the surface in a direction, the backend of the amoeba contracts, pushing the cytoplasm to fill the extending pseudopod. The pseudopod then forms a physical adhesion with the surface, which enables it to grip the surface and propel the amoeba forward. An amoeba also uses the pseudopods to capture food from the surroundings.   

If a solution of Sr(OH)2 has a concentration of 4.8E-5M, what is the concentration of its hydroxide ion? a cannot be determined; it does not...

Each molecule of strontium hydroxide, `Sr(OH)_2` , consists of 1 strontium ion (`Sr^2+`) and 2 hydroxide ions (`OH^-`). Therefore, the concentration of strontium ions is the same as that of strontium hydroxide, while the concentration of hydroxide ions would be twice that much.

Here, the concentration of strontium hydroxide is given as 4.8E-5 M or 4.8 x 10^-5 M. In other words, there are 4.8 x 10^-5 moles of strontium hydroxide in one liter of the solution. This also means that there would be 4.8 x 10^-5 moles of strontium ions and 2 x (4.8 x 10^-5) = 9.6 x 10^-5 moles of hydroxide ions in one liter of that solution.

This means that the concentration of hydroxide ions for this solution is 9.6 x 10^-5 M or 9.6E-5 M.

Thus, among the given options, choice B is correct.

Hope this helps.

Why do we have the Electoral College?

We have the Electoral College in the United States because the men who wrote the Constitution feared democracy.  They did not want to give the people too much direct power over the government.  One way they limited the people’s power was by preventing them from directly electing the president.

At the time that the Constitution was written, most educated people distrusted the idea of democracy.  There had never been a democratic country in modern times and even the Athenians and Romans were not truly democratic.  The Framers of the Constitution read philosophers like Plato, who emphasized that democracy was a bad form of government because it allowed a mass of people, most of whom knew nothing about running a country, to rule. They felt that democracy would inevitably collapse, or would turn into tyranny as ignorant people elected a demagogue to rule them. 

Because the Framers distrusted the idea of democracy, they tried to limit the degree to which the US would be democratic.  If we consider the presidency, the House of Representatives, the Senate, and the Supreme Court to be the four main parts of government, the Framers only allowed the people to elect one part directly.  The people got to elect the members of the House, but Senators were to be chosen by state legislatures, the president by the Electoral College, and Supreme Court justices by the president and the Senate.  The Electoral College was simply one way of insulating the government from the people so our system would not be excessively (in the Framers’ minds) democratic.

But why do we still have the Electoral College now that we no longer fear democracy?  The main reason is that the small states would not agree to change the Constitution to do away with it.  The Electoral College makes each state relevant as an entity, not just as a group of people.  It gives small states more power in the presidential voting because it gives them a disproportionate number of electors.    For example, California has more than 70 times as many people as Wyoming, but only about 18 times more electoral votes.  Because the Electoral College makes small states more important than their population size would warrant, those states would be unwilling to ratify a constitutional amendment to do away the College.

What do you think the idea of freedom means to Thoreau in Walden?

Thoreau supports freedom of thought, freedom of action, and freedom to live as one sees fit. These topics arise in many, if not all, of his writings. He and his family members participated in the antislavery movement and housed at least one or two runaway slaves temporarily in their home. Thoreau went to jail for one night to prove that he had the freedom to not pay a state tax that was irrelevant to him. He felt free enough to devise his own method of employment and finances:

“I found, that by working about six weeks in a year, I could meet all the expenses of living. The whole of my winters, as well as most of my summers, I had free and clear for study.” (Walden,“Economy,” paragraph 96)

Even though he enjoyed surveying land, he didn’t want to be saddled by owning it. He was concerned that such a tie would taint or interfere with his pure appreciation of it:

“As long as possible live free and uncommitted. It makes but little difference whether you are committed to a farm or the county jail.” (Walden, “Where I Lived, and What I Lived For,” paragraph 5)

After Ellen Sewell turned down marriage proposals by both Henry Thoreau and his brother John, Henry never pursued another close personal relationship. “All nature is my bride,” he wrote in his journal on April 23, 1857. He had enough self-imposed projects to occupy himself with in his advanced studies of the natural world. The freedom he created in his life allowed for it all.

What are functional foods?

Overview

Functional
foods are whole foods that naturally contain health-promoting
substances or contain added health-promoting substances. Also, functional foods
can act in concert with herbal supplements and drugs in the prevention and
treatment of disease. In contrast, neutraceuticals are active ingredients isolated
from foods and prepared in a medicinal form, and phytochemicals are chemical substances obtained from plants
that are biologically active but not nutritive.

The concept of functional foods is not new, as the medical and physiological benefits of some foods have been known for ages. The enhanced interest in functional foods is driven by a confluence of three factors: a greater understanding of the way functional food components exert medical benefits, the desire and capability of the food industry to produce new products based on these concepts, and interest and acceptance by the consumer. The new discipline of functional food science places emphasis in gaining knowledge of how functional food components can affect certain body functions related to health and disease.

Several methods exist to modify a natural (unmodified) food to be a functional food. Any natural food with an active ingredient can be modified to improve its effectiveness as a functional food. For example, the concentration of a particular component that is naturally present in the particular food could be increased to produce beneficial effects. Similarly, a component known to cause a detrimental health effect could be removed. A component not normally found in a particular food but known to produce a beneficial effect could be added. A component whose intake is usually excessive and could cause deleterious health effects can be replaced by a component with beneficial health effects. Finally, the bioavailability or stability of a component known to reduce the disease-risk potential of a particular food could be improved.

The value of functional foods has been recognized by the American Dietetic
Association and many other organizations. However, consumers should carefully
weigh the health claims and overall value of functional food products. The
U.S. Food and
Drug Administration (FDA) considers functional foods as
foods, not drugs, so manufacturers cannot claim that a functional food can cure,
mitigate, treat, or prevent any disease. The Nutrition Labeling and Education Act
(1990) does permit some exceptions, known as health claims, which state that a
substance included in the diet on a regular basis “may help reduce the risk” of a
certain disease. Most companies, however, prepare label claims based on
maintaining a normal, healthy structure or function of the human body. Although
so-called structure/function statements do not need approval from the FDA, the
label must show a disclaimer statement to this effect. An example of a
structure/function claim is the statement “helps build strong bones.”

Functional Food Types

In general, foods in their natural state, such as fruits and vegetables, oily fish, whole grains, and nuts and seeds, are among the best functional foods. They have active ingredients and a fine overall nutritional balance.

Probiotics and prebiotics. Probiotics
are beneficial bacteria added to dairy products such as yogurt to improve
gastrointestinal health. Prebiotics (oligosaccharide carbohydrates that are
abundantly found in artichokes, shallots, and onions) are growth media for
beneficial bacteria.

Polyphenols, anthocyanidins, flavones, and tannins. Polyphenols
are found in a variety of foods. They have an antioxidant effect, thought to
reduce the incidence of cancer and coronary heart disease. Anthocyanidins are
found in fruits, catechins in tea, and flavones in citrus. Flavones are widely
distributed in fruits and vegetables, and lignans are
found in flax, rye, and some vegetables. Tannins are found in cranberries and
cocoa.

Dietary fibers. Dietary fibers, those
food components obtained from plants that cannot be digested by the body, are
classified as either insoluble or soluble. Insoluble fiber consists of plant
cell-wall components, particularly cellulose, which form bulk in the diet and
promote the regularity of bowel movements. Soluble fiber dissolves in water and
thickens to form gels. Soluble fiber consistently has been shown to reduce total
cholesterol and LDL (low-density lipoprotein), or bad cholesterol, in the blood.
This reduction occurs through the reduced dietary fat and cholesterol uptake of
the intestine and through increased fecal excretion of bile acids (which are
derived from cholesterol).

Oats and barley contain an important fiber known as beta-glucan,
a complex carbohydrate made of glucose units. Oatmeal has become a popular cereal
for this reason, and oat bran too is marketed as a cereal or as an ingredient in
other foods. Guar gum, pectin, and psyllium also contain abundant soluble
fiber.

Omega-3 fatty acids. Omega-3 fatty acids have been found to be
beneficial for the prevention of heart disease. (Omega-3 refers to chemical
structure.) The omega-3 fatty acids eicosapentaenoic acid and docosapentaenoic
acid are found in abundance in fatty fish, such as herring, anchovies, mackerel,
salmon, and sardines. Another omega-3 fatty acid, linolenic acid, is found in
walnut, soybean, and canola oils. The fish oils have a more protective effect
than the plant oils. Omega-3 fatty acids are converted to biologically active
compounds such as prostaglandins and leukotrienes, which have anti-inflammatory,
antithrombic, antiarrythmic, and vasodilatory effects.

Plant sterols. Plant sterols are similar in structure to cholesterol and are found in the diet as sitosterol, stigmasterol, and campesterol. A compound made from sitosterol, known as stanol ester, is incorporated into a commercial margarine as a cholesterol-reducing agent. Nuts act as antioxidants and have a cholesterol-lowering effect.

Carotenoids. Carotenoids represent a large group of
natural pigments found in plants (including yellow and orange fruits and
vegetables such as carrots, apricots, squash, and sweet potatoes) and in dark
green vegetables such as spinach, kale, and collard greens. The most common
dietary carotenoids are alpha-carotene, beta-carotene, and lutein.
Because of the nature of their molecules, carotenoids have strong antioxidant
activity. Evidence shows that carotenoids have a protective effect against heart
disease and some cancers.

Research

Most studies on functional foods have been observational; the great time and expense involved in clinical trials make observational studies the best option. Although there are many types of observational studies of functional foods, all attempt to relate the incidence of disease in a population with the dietary intake of a particular food. Observational studies can provide data from a large number of people in a relatively short period of time at low cost; however, these studies have been criticized for not controlling variables and for being subject to bias. Observational studies, however, can provide a strong indication of trends.

Intervention studies involve assigning participants to control or treatment groups, marked by various types and amounts of functional food components. The groups are followed over time, and researchers note the incidence of disease among groups. In a clinical trial, the groups are randomly assigned. Randomization reduces biases in evaluation of treatment and control groups by making the groups equal in all respects except for the treatments applied.

Before beginning a study, researchers start with basic scientific knowledge regarding functions that are sensitive to modification by food components. These functions could be genetic, cellular, biochemical, or physiologic. Quite often, instead of examining the effect of the component on an outcome, researchers may use a marker that is related to the outcome. For example, researchers could study the effect of an ingredient on cholesterol levels instead of waiting for heart disease to develop. Markers must be able to predict the beneficial or detrimental effects of a food component. The body could respond to the intake of a food component through changes in body fluid levels of certain metabolites or enzymes. Measurement of changes in body tissues, such as extent of narrowing of carotid arteries, can be related to the development of atherosclerosis. Markers need to be sensitive and specific to the disease condition.

Actions of Functional Foods and Their Components

Probiotics. Probiotics are bacteria established in the intestinal
tract that exert a beneficial effect. The term “probiotics” was coined to contrast
with antibiotics, which destroy harmful bacteria. Probiotics are
normally added to dairy products as lactobacilli and bifidobacteria. These
bacteria promote improved intestinal microbial balance with a reduction in harmful
microbes. Probiotics are beneficial in preventing infection and enhancing the
immune system. They aid in preventing pathogens from entering the bloodstream
through the mucosal epithelial cells by increasing mucin production and reducing
permeability.

Probiotics also enhance antibacterial and anti-inflammatory activities of the intestinal epithelium by stimulating synthesis of specialized protective proteins. Clinical studies have shown that probiotics can reduce the symptoms of irritable bowel syndrome and can be beneficial in maintaining remission in cases of ulcerative colitis and pouchitis (inflammation of the intestinal wall). Other studies have shown that probiotics can help prevent necrotizing enterocolitis in infants.

Prebiotics. Prebiotics are indigestible oligosaccharide carbohydrates that can be fermented by lactobacilli and bifidobacteria. Prebiotics, along with probiotics, act in concert to produce the same beneficial results. Prebiotics can serve as fermenting media for probiotic bacteria already in the intestinal tract or in combination with introduced probiotics. Studies are ongoing to determine appropriate conditions for the use of intact cereals as media for the growth of probiotic strains and to develop processing methods to isolate sources of water-soluble fiber that can serve as prebiotics.

Plant sterols. A review article indicated that plant sterols and tree nuts were beneficial for the prevention of coronary heart disease in most clinical trials, while flavonoids in dark chocolate may protect LDL cholesterol from undergoing oxidative modification. Plant sterols are believed to interfere with the absorption of cholesterol from the small intestine by preventing it from dissolving in the micellular structure. Plant sterols are added to margarine products as a cholesterol-lowering agent, but some consumers have concerns about weight gain. A meta-analysis of fifty-nine randomized clinical trials found that plant sterols that were added to milk, orange juice, or yogurt lowered total cholesterol and LDL cholesterol, but did not do so when added to breads or meats.

Nuts. Many clinical studies have shown that the consumption of
walnuts, almonds, pecans, pistachio nuts, and macadamia nuts result in lowered
total cholesterol and LDL cholesterol. Epidemiological studies found an inverse
relationship between nut consumption and the risk of coronary heart disease.
Scientists believe that the beneficial effect of nuts comes from their high
content of polyunsaturated fatty acids. Nuts may improve endothelial (blood-vessel
wall) function too, resulting in better vasodilation. Nuts also may act as
antioxidants, reducing LDL oxidation, one of the steps
leading to plaque formation.

Polyphenols. Polyphenols, also known as flavonoids, are widespread in commonly consumed foods. Several hundred have been identified in fruits, vegetables, legumes, whole grains, and nuts, and in beverages such as tea, coffee, and wine. Many studies have examined polyphenols; however, many of these studies have been in vitro (in a laboratory) and at high doses. Epidemiological studies with humans have shown a protective effect of polyphenols on reducing fatal or nonfatal coronary artery disease. Epidemiological studies also have shown a protective effect against lung and colorectal cancers.

Procyanidins and isoflavones. Intervention (controlled) studies
have shown that procyanidins found in red wine, grapes, cocoa, cranberries, and
apples have pronounced beneficial effects on the vascular system, effects
including antioxidant activity, decreased platelet aggregation, decreased LDL
concentration, and increased HDL concentration. Isoflavones
may have effects on bone mineral density and bone mineral content in women who are
postmenopausal.

Bibliography

American Dietetic Association. “Functional Foods.” Available at http://www.eatright.org/public.

Institute of Food Technologists. “Functional Foods Expert Report: Opportunities and Challenges.” Describes in detail FDA regulations governing health-related claims on food labels. Available at http://www.ift.orgknowledge-center.

Milner, John. “Functional Foods: The U.S. Perspective.” American Journal of Clinical Nutrition 71 (2000):

1654-1659. An overview of functional foods. Includes discussion of public interest and the means of evaluation.

Roberfroid, Marcel. “Concepts and Strategy of Functional Food Science: The European Perspective.” American Journal of Clinical Nutrition 71 (2000): 1660-1664. Provides an introduction to the science of functional foods and their applications.

Saulnier, Delphine, et al. “Mechanisms of Probiosis and Prebiosis: Considerations for Enhanced Functional Foods.” Current Opinion in Biotechnology 20, no. 2 (2009): 135-141. Discusses the mechanisms and applications of probiotics and prebiotics.

Vita, Joseph. “Polyphenols and Cardiovascular Disease: Effects on Endothelial and Platelet Function.” American Journal of Clinical Nutrition 81 (2005): 292-297. A review of epidemiologic studies that support a relationship between higher intakes of polyphenolic flavonoids and reduced risk of cardiovascular disease.

In Chapter 4 of S. E. Hinton's novel That Was Then, This Is Now, what new problems does Charlie have?

In the novel That Was Then, This Is Now, Charlie is a tough, local kid who owns his own bar where Bryon and Mark hang out and hustle people at billiards. Bryon respects Charlie because he is a smart individual who owns a successful business and seems to have a lot going for him. In Chapter 3, Bryon asks Charlie if he can borrow his car to take Cathy to a school dance. Charlie tells Bryon that he can borrow his car as long as he brings it back with enough gas in it. Bryon is shocked that Charlie allowed him to borrow his car, and Byron picks Cathy up at her home later that night. While Bryon is at the school dance, Mark gets into a fight in the parking lot and is severely injured after one of Angela Shepard's friends hits him in the head with a bottle. At the beginning of Chapter 4, Bryon returns Charlie's car and explains to him what happened. Bryon mentions that Charlie didn't seem to interested because he was having his own troubles. Bryon says, "He’d got his draft notice" (Hinton 31). Later on in the novel, Charlie tells Bryon that he was rejected from entering the service because of his police record. When Bryon asks Charlie what he did, Charlie tells him that he cut a guy's throat when he was twelve years old. 

How do you approach an essay question that uses "To what extent do you agree" as its stem?

In my experience, teachers never assign a question like this if the answer is anything other than “to some extent.” In other words, whatever the proposition after the stem is, it is always partly true and partly untrue. So, if there is a question that asks “to what extent was the US responsible for the Allied victory in WWII in Europe,” I assume that the instructor believes that the US was partly responsible for the victory, but that there were also ways in which the US was not responsible. Alternatively, imagine if you are asked “to what extent were Romeo and Juliet responsible for their own deaths?” In that case, I would expect that the teacher believes the couple was partly responsible but that other factors contributed to their demise.

When I assign questions like this, I expect to see my students examine both sides of the issue. I expect them to provide reasons why the statement is untrue and why it is true. So, with the Romeo and Juliet example, I would expect a student to provide reasons why the two main characters were responsible for their own deaths, but I would also expect to see some blame placed on such people as their parents and Friar Laurence. With the WWII question, I would want to see discussion of the importance of the US contribution, but I would also expect students to discuss how important Soviet involvement was and how badly the Soviets weakened the German military. I, personally, do not expect students to give a specific answer to the “to what extent question.” I do not expect them to say that the US was, for example, 70% responsible. If a student concludes that the US was more responsible than any other country, that is enough for me. However, different instructors may have different expectations.

So, I approach this type of question by trying to find arguments both for and against the proposition. I set out both sets of arguments in my essay and I try to decide, if possible, whether the proposition is, on balance, mostly true or mostly false.

What is the significance of the main characters in the book So Long a Letter?

I argue that the main characters of Mariama Bâ’s So Long a Letter are significant largely because they represent a marginalized population to Western readers. Indeed, the novella foregrounds the struggles of Senegalese women addressing customs such as polygamy in an Islamic culture. For the majority of Western readers, this voice is incredibly rare to find in literature. Here, Bâ confronts the issues that women face in Senegal through her frank characterization of Ramatoulaye Fall and her uncensored letter to her best friend, Aissatou Bâ. Ramatoulaye often questions the conventions in her culture that marginalize women, especially polygamy:

“I have heard of too many misfortunes not to understand my own. There was your own case, Aissatou, the cases of many other women, despised, relegated or exchanged, who were abandoned like a worn-out or out-dated boubou” (41).

Later in the novel, Bâ is startlingly direct in her call for women to become politically active. The fact that this is coming from a Senegalese woman writing from the perspective of another disenfranchised Senegalese woman is especially potent:

“Women must be encouraged to take a keener interest in the destiny of the country…. If men alone are active in the parties, why should they think of the women?” (62).

Thus, the main characters are significant because they perfectly capture the issues women in Senegal face, and they are direct in their critique of their conditions.

`int_0^a x^2 sqrt(a^2 - x^2) dx` Evaluate the integral

`int_0^ax^2sqrt(a^2-x^2)dx`

Let's evaluate the indefinite integral by applying integral substitution,

Let `x=asin(u)`

`dx=acos(u)du`

`intx^2sqrt(a^2-x^2)dx=int(asin(u))^2sqrt(a^2-(asin(u))^2)acos(u)du`

`=inta^2sin^2(u)sqrt(a^2-a^2sin^2(u))acos(u)du`

`=a^3intsin^2(u)cos(u)sqrt(a^2(1-sin^2(u)))du`

`=a^3intsin^2(u)cos(u)asqrt(1-sin^2(u))du` 

Now use the identity:`1-sin^2(x)=cos^2(x)`

`=a^4intsin^2(u)cos(u)sqrt(cos^2(u))du`

`=a^4intsin^2(u)cos^2(u)du`

Now use the identity:`cos^2(x)sin^2(x)=(1-cos(4x))/8`

`=a^4int(1-cos(4u))/8du`

`=a^4/8int(1-cos(4u)du`

`=a^4/8(int1du-intcos(4u)du)`

`=a^4/8(u-sin(4u)/4)`

Substitute back `u=arcsin(x/a)`

`=a^4/8(arcsin(x/a)-sin(4arcsin(x/a))/4)`

add a constant C to the solution,

`=a^4/8(arcsin(x/a)-1/4sin(4arcsin(x/a)))+C`

Now let's evaluate the definite integral,

`int_0^ax^2sqrt(a^2-x^2)dx=[a^4/8(arcsin(x/a)-1/4sin(4arcsin(x/a)))]_0^a`

`=[a^4/8(arcsin(a/a)-1/4sin(4arcsin(a/a)))]-[a^4/8(arcsin(0/a)-1/4sin(4arcsin(0/a)))]`

`=[a^4/8(arcsin(1)-1/4sin(4arcsin(1)))]-[a^4/8(arcsin(0)-1/4sin(4arcsin(0)))]`

`=[a^4/8(pi/2-1/4sin(4*pi/2))]-[a4/8(0-1/4sin(4*0))]`

`=[a^4/8(pi/2-1/4sin(2pi))]-[0]`

`=[a^4/8(pi/2-1/4(0))]`

`=a^4/8(pi/2)`

`=(pia^4)/16`

`int_0^0.6 x^2 /sqrt(9 - 25x^2) dx` Evaluate the integral

`int_0^0.6x^2/sqrt(9-25x^2)dx`

Let's first evaluate the indefinite integral by applying the integral substitution,

Let `x=3/5sin(u)`

`=>dx=3/5cos(u)du`

Plug in the above in the integral,

`intx^2/sqrt(9-25x^2)dx=int(3/5sin(u))^2/(sqrt(9-25(3/5sin(u))^2))(3/5cos(u))du`

`=int(27sin^2(u)cos(u))/(125sqrt(9-9sin^2(u)))du`

`=int(27sin^2(u)cos(u))/(125sqrt(9(1-sin^2(u))))du`

use the identity:`1-sin^2(x)=cos^2(x)` `<br> `

`=int(27sin^2(u)cos(u))/(125*3sqrt(cos^2(u)))du`

`=int(9sin^2(u)cos(u))/(125cos(u))du`

`=9/125intsin^2(u)du`

Now use the identity:`sin^2(x)=(1-cos(2x))/2`

`=9/125int(1-cos(2u))/2du`

`=9/250int(1-cos(2u))du`

`=9/250(int1du-intcos(2u)du)`

`=9/250(u-sin(2u)/2)`

We have taken `x=3/5sin(u)`

`=>u=arcsin(5/3x)`

Substitute back u and add a constant C to the solution,

`=9/250(arcsin(5/3x)-1/2sin(2arcsin(5/3x)))+C`

Now let's evaluate the definite integral,

`int_0^0.6x^2/sqrt(9-25x^2)dx=[9/250(arcsin(5/3x)-1/2sin(2arcsin(5/3x)))]_0^0.6`

`=[9/250(arcsin(5/3*0.6)-1/2sin(2arcsin(5/3*0.6)))]-[9/250(arcsin(5/3*0)-1/2sin(2arcsin(5/3*0)))]`

`=[9/250(arcsin(1)-1/2sin(2arcsin(1)))]-[9/250(arcsin(0)-1/2sin(2arcsin(0)))]`

`=[9/250(pi/2-1/2sin(2*pi/2))]-[0]`

`=[9/250(pi/2-1/2sin(pi))]`

`=[9/250(pi/2-1/2*0)]`

`=(9pi)/500`

`=0.05655`

` `

` `

` `

` `

` `

Rousseau has been interpreted as a liberal, a conservative, and a totalitarian. Which of these interpretation of you agree with and why?

I would argue that trying to apply terms such as liberal, conservative, or totalitarian really get in the way of understanding Rousseau rather than contributing to our knowledge of him. The terms liberal and conservative, especially, have changed meanings so much over the centuries that they seem to obfuscate rather than clarify our understanding of earlier figures.

Calling Rousseau a totalitarian seems the least helpful of the three possibilities, given his emphasis on individual freedom and his opposition to Hobbes' philosophy of human nature and governance.

Rousseau's idealization of the "noble savage" is in many ways nostalgic, hearkening back to a pastoral state intermediate between primitive brutality and modern decadence. In some ways, this nostalgia is conservative, as is Rousseau's focus on spirituality, but his notion of the natural goodness of human nature and opposition to many forms of convention make his position quite different than that of many groups that would call themselves conservative. His emphasis on human freedom and opposition to convention might seem to align him with liberalism, but the liberals of his period were secularists and enthusiastic about the progress of technology and knowledge, views Rousseau did not share. 

Perhaps it is best simply to say that he was an iconoclast whose views do not fit neatly in any narrow category. 

I have a paper on the Confessions of Saint Augustine and Garry Wills' short book Augustine's Confessions: A Life. What are some of the...

One possible subject you may want to concentrate on in your paper is how Saint Augustine's childhood shaped him. While Saint Augustine does not discuss his early childhood in any depth in his Confessions, Wills writes "we can find traces in his later writing of the bright-eyed and observant boy he must have been" (page 3). Wills also examines the mosaics in Saint Augustine's Roman African town as a model for the orderly way in which Saint Augustine later looked at the world. It might be interesting to focus on the ways in which his childhood affected him. In addition, another sub-question is how his mother, Monnica, affected him and his eventual conversion. 

Another sub-question to focus on is why Augustine lost faith in Manichaeism, a philosophy that divided the cosmos into good and evil, and how he was eventually converted to Christianity. When Augustine was finally able to convert, how did he prepare for his conversion and how did he make sense of his past sins? Wills contends that Augustine was not the playboy some have painted him but was only obsessed with controlling his own body. How do modern readers of Augustine make sense of his retelling of his sexual sins? 

Another interesting question is how the Confessions resembles a modern-day autobiography and how it does not. It provides a great deal of insight into Augustine's inner turmoil. How does the reader get to know Augustine better through his Confessions, and how does Wills's book augment or change what the reader learns from the Confessions?

In "The Canterville Ghost" by Oscar Wilde, what does Mrs. Otis want Mrs. Umney to do about the bloodstain?

Mrs. Otis wants Mrs. Umney to clean up and get rid of the bloodstain. 

In the first part of the story, Mrs. Umney is taking the Otis family on a brief tour of the Canterville Chase.  She leads them into the library, where tea has been set out for everybody to enjoy.  While taking the tea break, Mrs. Otis discovers the bloodstain on the floor and demands that it be cleaned up immediately.

"How horrid!" cried Mrs. Otis; "I don't at all care for blood-stains in a sitting-room. It must be removed at once."

Mrs. Umney explains that the bloodstain belongs to the former Lady Eleanore de Canterville, who was murdered by her husband.  The bloodstain has been on the floor for more than 300 years, and nobody can get rid of it. 

Washington Otis thinks that is all nonsense and pulls out some special cleaner.  Why he carries around special cleaning agents is beyond me, but I digress.  Washington drops to his knees and scrubs the floor clean.  No more bloodstain.  

"That is all nonsense," cried Washington Otis; "Pinkerton's Champion Stain Remover and Paragon Detergent will clean it up in no time," and before the terrified housekeeper could interfere, he had fallen upon his knees, and was rapidly scouring the floor with a small stick of what looked like a black cosmetic. In a few moments no trace of the blood-stain could be seen.

Unfortunately, Washington's extreme cleaning only works for that one day, because the bloodstain is back again by the following morning.  

In Julius Caesar, what does Brutus mean by his final words: "Caesar, now be still; /I killed not thee with half so good a will"? Why does Brutus...

Brutus utters these words almost at the end of Scene 5, Act 5. He has asked Strato to hold up his sword so that he may run into it. Once he has done so, he utters these final words. 

What Brutus means is that Caesar's spirit can now find peace because it has been avenged. Furthermore, he says that he has now taken his own life with a greater purpose and more determination that he had when he stabbed Caesar. What Brutus also implies is that he has more reason to kill himself now than the ones he had to assassinate Caesar.

Brutus realises that his time has come. They have been fighting a losing war. Antony and Octavius' troops have gained an advantage and there is no chance of a victory. He stated earlier in this scene:

...Brutus' tongue
Hath almost ended his life's history:
Night hangs upon mine eyes; my bones would rest,
That have but labour'd to attain this hour.

Whilst he was in his tent, Brutus was confronted by Caesar's ghost and it told him that it would visit him one last time on the plains of Philippi. This has now happened. He has seen Caesar's ghost the second time and knows that his time has come, as he tells Volumnius:

The ghost of Caesar hath appear'd to me
Two several times by night; at Sardis once,
And, this last night, here in Philippi fields:
I know my hour is come.

Added to this, Cassius had also asked Pindarus to stab him with the sword he used to slay Caesar. This gives Brutus a further incentive to also take his own life. In addition, Portia, Brutus' wife, has also committed suicide by swallowing hot coals. He has nothing to return to. It is a matter of honour to him that he not be taken alive for he does not want to be paraded through the streets of Rome as a failure and a slave. It would be humiliating. 

Brutus' suicide links with the promise he had made to the crowd during his speech in the marketplace to explain why Caesar had been killed. He told the citizens, in part, in Act 3, scene 2:

...as I slew my best lover for the
good of Rome, I have the same dagger for myself,
when it shall please my country to need my death.

This moment has now arrived and since Brutus is a man of integrity, he keeps his promise. He has become an enemy of Rome and his country has sworn vengeance and, therefore, seek his death.

Brutus had stated earlier, in Act 5 scene 2, that he deemed suicide a cowardly and despicable act. He told Cassius on that occasion:

...I did blame Cato for the death
Which he did give himself, I know not how,
But I do find it cowardly and vile,
For fear of what might fall,...

He did, however, change his mind when Cassius asked him if he would be happy to be marched through the streets of Rome after his defeat. He then declared:

No, Cassius, no: think not, thou noble Roman,
That ever Brutus will go bound to Rome;
He bears too great a mind.

In Shakespeare's play Julius Caesar, how is Brutus' greatness also his weakness?

What distinguishes Brutus from the others is that he acts on noble intentions, but these also make him naïve. 

Unlike many of the other conspirators, Brutus has no ambition in the purest sense.  He involves himself in the conspiracy because he believes it is for the good of Rome.  As long as Caesar is in power, by Brutus’s thinking, Rome cannot remain a republic.  Caesar will make himself king. 

Brutus does not desire to be king.  He wants things to go back to the way they were in what he sees as the golden days of Rome.  He pictures an idealized Rome, where the senate and republic reign supreme.  To this end, he is willing to assassinate Caesar. 

When Brutus decides that Caesar has to die, he convinces himself with a flowery speech about Caesar’s death. 

It must be by his death: and for my part,
I know no personal cause to spurn at him,
But for the general. He would be crown'd:
How that might change his nature, there's the question.
It is the bright day that brings forth the adder;
And that craves wary walking. (Act 2, Scene 1) 

While it may be noble to want to kill Caesar only for the good of his country, Brutus’s desire to make the assassination honorable causes trouble for his group.  Noble and practical are not the same thing.  Brutus refuses to kill anyone other than Caesar, leaving Mark Antony free to wreak havoc.  He also insists that the killing be public in the capital at the senate meeting, which makes it more dangerous.  The group has to get Caesar to that spot on that day, and prevent anyone from interrupting them. 

Brutus even allows Mark Antony to speak after him at Caesar’s funeral.  This may be noble, but it is a huge mistake.  Antony turns the people against Brutus and the others, and they have to go on the run and on the offensive. 

After his death, Antony acknowledges that Brutus may have had good intentions. 

This was the noblest Roman of them all:
All the conspirators save only he
Did that they did in envy of great Caesar;
He only, in a general honest thought
And common good to all, made one of them.
His life was gentle, and the elements
So mix'd in him that Nature might stand up
And say to all the world 'This was a man!' (Act 5, Scene 5) 

Thus, Brutus’s greatest strength was also his greatest weakness.  He truly loved Rome, and he was not an ambitious person.  However, he also felt that he could control the forces that he was trying to direct, and make sure that everything fit his idealistic version of tyranticide.  He was in over his head, and continually failed to acknowledge how things were really going.

Why did Jordan say she liked Nick in Chapter Three of The Great Gatsby?

By Chapter Three of The Great Gatsby, Jordan Baker and Nick Carraway have spent quite some time together and are gradually getting to know each other. Nick remembers a story that he had heard about Jordan's first big golf tournament and how she may have moved her ball in the semi-finals; he realizes that she prefers to avoid clever men because of this, feeling that it's safer. Nick decides that Jordan is "incurably dishonest" and unable to "endure being at a disadvantage." Meanwhile, he describes himself as "one of the few honest people that I have ever known." 

They are driving together one day when Nick comments on her terrible driving; Jordan spits back that she is sure other people are more careful and that they will keep out of her way. Nick asks, "Suppose you met somebody just as careless as yourself," and Jordan proclaims, "I hope I never will...I hate careless people. That's why I like you." 

Despite knowing about these poor character traits, Nick is enchanted by this statement, and declares that "for a moment I thought I loved her."

it takes 7 hours for Isabella to rake leaves by herself but her brother Matthew can work three times as fast. if they work together how long will...

If we let r be the rate Isabella rakes, then 3r is the rate at which Matthew rakes. For a unit job, their combined rate is r+3r=4r. Since a unit job took 7 hours, the time it takes for the combined effort is 7/4 hours.

It will take them 7/4 hours or 1 hour and 45minutes to finish the raking.

** To make this concrete, suppose the area to be raked is 28 square meters. Since Isabella can finish the job in 7 hours, she rakes 4 square meters per hour. Now Matthew is three times as fast, so he rakes at 12 square meters per hour. Together they rake 4+12=16 square meters per hour. Since the job is 28 square meters, the time required is 28/16=7/4 hours as above.

What are the differences between an approach and a theory?

These two concepts relate to scientific research and understanding, though in different ways. A theory is an explanation for how facts relate to one another, while an approach is a methodology for obtaining those facts in the first place.

A theory is a framework for understanding relationships between observable facts. In other words, they explain observations. Hypotheses become theories when enough data is gathered to support the hypothesis. Theories are mutable, and can be strengthened or weakened based on new information that is observed. It’s important to note that the facts themselves won’t change, but rather the explanation of the facts. Jamie Tanner, professor of biology at Marlboro College, explains the relationship between theories and facts as follows:

For example, we have ample evidence of traits in populations becoming more or less common over time (evolution), so evolution is a fact but the overarching theories about evolution, the way that we think all of the facts go together might change as new observations of evolution are made.

An approach, on the other hand, is the framework and context with which somebody conducts research. It can refer to both the method of interpretation used as well as the actual type of research conducted. For example, if investigating mental illness, an anthropologist would consider the context of the communal norms, a sociologist would consider the context of interaction between individuals, and a psychologist would consider how mental illness is experienced by the individual.

What happens when solutions of aluminum iodide and mercury(II) chloride are mixed together?

Aluminum iodide and mercury (II) chloride react when mixed.  The reaction is called a double replacement reaction and produces aqueous aluminum chloride and a mercury iodide precipitate.  The reaction is as follows:

2AlI3 (aq) + 3HgCl2 (aq) `->`   2AlCl3 (aq) + 3HgI2 (s)

In double replacement reactions, the cations within each reactant molecule switch anion partners with each other.  In chemistry, cations are positively charged ions and are given first in chemical formulas and anions are negatively charged ions.  In this example, Al3+ and Hg2+ are the cations and I- and Cl- are the anions.  Aluminum iodide consists of 1 aluminum and 3 iodine ions to balance the 3+ charge on the aluminum.  Mercury chloride consists of 1 mercury and 2 chloride ions to balance the 2+ charge on the mercury. 

The products are also electrically neutral.  Aluminum chloride remains dissolved in solution and consists of 1 aluminum and 3 chlorides to balance the 3+ charge on the aluminum.  Mercury chloride is a solid that precipitates out of solution and consists of 1 mercury and 2 iodide ions to balance the 2+ charge on the mercury.

What is thermoreception?

Introduction

Humans have thermoreceptors that can detect the flow of heat energy. These specialized sensory receptors can detect the flow of heat as a change in temperature, and convert this information into nerve impulses. Conversion into nerve impulses places the information into a form that can be processed by the central nervous system, allowing a compensating response, if required, to be initiated.

Humans and other mammals have two kinds of thermoreceptors. One type, called the warm thermoreceptor, becomes active in sending nerve impulses when the body surroundings or an object touched reaches temperatures above 30 degrees Celsius. Nerve impulses from the warm thermoreceptors increase proportionately in frequency as the temperature rises to about 43 degrees Celsius; past this temperature, impulses from the warm thermoreceptors drop proportionately in frequency until they become inactive at about 50 degrees Celsius.

The second type of thermoreceptor becomes active in generating nerve impulses at temperatures below about 43 degrees Celsius. Nerve impulses from these receptors, called cold thermoreceptors, increase proportionately as temperatures fall to about 25 degrees Celsius. Below this temperature, the frequency of nerve impulses generated by the receptors drops proportionately; as temperatures fall to about 5 to 10 degrees Celsius, activity of the cold thermoreceptors falls to zero. The activity of cold and warm thermoreceptors overlaps between temperatures of about 30 and 40 degrees Celsius. Within this range, the sensation of heat or cold results from an integration in the brain of nerve impulses generated by both cold and warm receptors.

At temperatures below about 15 degrees and above about 45 degrees Celsius, pain receptors become active and increase proportionately in activity as temperatures rise or fall beyond these levels. There is a narrow range of overlap of the limits of pain receptors and thermoreceptors, so that temperatures between about 5 and 15 degrees Celsius are felt as both cold and pain (or as “freezing cold”) and temperatures between about 43 and 50 degrees Celsius are felt as both heat and pain (or “burning hot”). Temperatures beyond the 5-degree and 50-degree limits for the thermoreceptors stimulate only the pain receptors and are felt primarily or exclusively as pain. Curiously, the cold receptors become active as pain receptors as the temperature rises above about 45 degrees Celsius. The dual activity of the cold thermoreceptors may account for the fact that freezing cold and burning heat may produce a similar sensation.

Adaptation Process

Both types of thermoreceptors adapt quickly as the temperature stabilizes. Adaptation refers to the fact that as a stimulus is maintained at a constant level, the nerve impulses generated by a receptor drop in frequency. In effect, the receptor undergoes a reduction in sensitivity if the stimulus remains constant. If the stimulus changes, the receptor again generates nerve impulses at a frequency proportional to the intensity of the stimulus. The ability of receptors to adapt makes them sensitive to a change in stimulus, which is often the factor of greatest importance to an appropriate response.

The rapid adaptation of thermoreceptors is part of common experience. In going from the outdoors into a warm room on a cold day, one immediately detects the warmer temperature and has a resultant strong sense of a temperature change. After a few minutes, one no longer notices the temperature difference, as one’s thermoreceptors adapt and reduce their generation of nerve impulses. If the temperature of the room changes by only a degree or so, however, the generation of impulses by the thermoreceptors increases again, and one becomes aware of the change.

Spatial Summation and Receptor Location

Thermoreceptors also show strong spatial summation. If only a very small region of the body is stimulated, one has difficulty discerning whether a temperature change has been experienced, or even whether the stimulus is hot or cold. As the surface area stimulated increases, impulses arriving in the brain from thermoreceptors are summed, so that perception of the change increases proportionately. If only a square centimeter of skin is stimulated by a warm or cold probe, for example, one might not be able to detect a temperature change smaller than about 1 degree Celsius. If the entire body surface is stimulated, as in total immersion in water, one becomes exquisitely sensitive to changes in temperature. Summation of information from all surface thermoreceptors may allow detection of temperature changes as small as one hundredth of one degree Celsius.

Thermoreceptors in humans are most numerous at the body surface, where they are located immediately under the skin. Each thermoreceptor can detect temperature changes over an area of about 1 millimeter in diameter. Cold thermoreceptors occur in greater numbers at the body surface than warm receptors: Depending on the body region, there may be as many as three to ten cold thermoreceptors for each warm thermoreceptor. Thermoreceptors of both types are particularly densely distributed in the skin of the tongue and the lips. In these regions, there may be as many as twenty to thirty or more thermoreceptors per square centimeter of surface. About a third as many thermoreceptors occur in the skin of the fingertips. In other parts of the body surface, only a few thermoreceptors occur per square centimeter.

Physical and Chemical Mechanisms

Although the locations of cold and heat receptors can be pinpointed on the body surface by touching the skin with a warm or cold probe, it has proved difficult to detect particular structures responsible for thermoreception. One group of cold thermoreceptors, however, has been identified as branched nerve endings that terminate near the inner surfaces of cells in the skin. Presumably, other cold thermoreceptors and the warm thermoreceptors are little more than naked nerve endings that cannot be distinguished from pain and some touch receptors, which have a similar appearance.

Little is understood about the physical and chemical mechanisms underlying thermoreception; however, it is considered likely that the reception mechanism depends on increases and decreases in chemical reaction rates in the receptor cells as the temperature rises and falls. In general, chemical reaction rates approximately double for each 10-degree increase in temperature or are halved for each 10-degree fall. Thermoreceptors probably respond to these increases or decreases in chemical reaction rates rather than directly detecting the changes in heat flow responsible for changes in temperature. The thermoreceptors responsible for detecting heat are also sensitive, to some degree, to chemicals. This explains why spices such as red peppers give the sensation of heat when placed on the tongue or rubbed into the skin. Other chemicals, such as menthol, feel cold on the tongue or skin.

Body Temperature Maintenance

Thermoreception has two primary functions in warm-blooded animals such as humans. One is detection of extreme temperatures, so that a person can respond to avoid tissue damage by burning or freezing. The second is maintenance of normal body temperature of 37 degrees Celsius.

Maintenance of body temperature, or homeostasis, involves both conscious and automated responses. At temperatures not too far above and below the range of comfort (about 22 to 24 degrees Celsius), one feels consciously warm or cool and responds by one or more voluntary methods to decrease or increase skin temperature, such as donning or removing clothing. The automated responses maintaining body temperature are complex and involve a variety of systems. Changes in internal temperature are detected by thermoreceptors in the body interior, particularly in the hypothalamus—a brain structure containing the center that detects and regulates internal body temperature. The thermoreceptors of the hypothalamus are extremely sensitive to shifts from the normal body temperature of 37 degrees Celsius. If such changes occur, the hypothalamus triggers involuntary responses that adjust body temperature.

If the internal body temperature rises above 37 degrees, sweat glands in the skin are stimulated to release their secretion, which evaporates and cools the body surface. Heat loss is also promoted by dilation of the peripheral vessels, which increases blood flow to the body surface. Blood cooled at the surface is carried to the body interior by the circulatory system, where it removes heat from internal regions and causes a drop in body temperature. In addition to these cooling mechanisms, release of thyroxin from the thyroid gland is inhibited. The resulting reduction in the concentration of this hormone in the circulation slows the rate at which body cells oxidize fuel substances and diminishes the amount of heat released by these reactions in the body.

If the internal body temperature falls below 37 degrees Celsius, a series of automated responses with opposite effects triggered. Peripheral blood vessels contract, reducing the flow of blood to the body surface. The output of thyroxin from the thyroid gland increases; the increased thyroxin concentration stimulates body cells to increase the rate at which fuel substances are oxidized to release heat within the body. Although the effect of the response in humans is not pronounced, a drop in internal temperature also stimulates contraction of small muscles at hair roots over the body. The contraction, which is felt as “goose bumps,” raises body hairs and increases the dead-air space at the surface of the body. If the drop in internal temperature becomes more extreme, shivering caused by rhythmic contractions of voluntary muscles is induced. Shivering increases body temperature through the heat released by the muscular contractions.

Role of the Hypothalamus

The hypothalamus has been identified as the region of the brain regulating body temperature through observations of the effects of injuries and electrical stimulation. Damage to the hypothalamus can inhibit such temperature-regulating responses as sweating and dilation or constriction of peripheral blood vessels. Conversely, experimental electrical stimulation of the hypothalamus can induce the regulatory responses. These observations indicate that the primary temperature-regulating center of the hypothalamus is in its anterior or preoptic region. The automated responses triggered by the hypothalamus in addition to conscious responses allow humans to maintain an almost constant body temperature in the face of a wide variety of environmental conditions. These combined automated and conscious responses allow humans to survive and remain active in a wider range of environmental conditions than any other animal.

The body temperature maintained by the thalamus is not actually set perfectly and constantly at 37 degrees. For most persons, the internal body temperature varies over a range of about 0.6 degree, with the lowest temperatures in the early morning and the highest point at about four to six in the afternoon. This daily variation in body temperature is called the circadian temperature rhythm.

Although the body temperature is normally set at 37 degrees, the set point can be adjusted upward to produce fever as a part of the body’s response to infection by invading organisms. Raising the body temperature above 37 degrees results from the same automated responses that normally raise internal temperatures—shivering, constriction of peripheral blood vessels, and an increase in the rate of metabolic reactions.

Fever

Several types of bacteria secrete substances that can directly stimulate the hypothalamus to raise its set point and induce fever. Substances of this type, capable of inducing fever, are termed pyrogens. Other substances derived through the breakdown of infecting bacteria, or from substances released through the breakdown of body tissues in disease, particularly fragments of some body proteins, can indirectly trigger the hypothalamus to raise its set point. These substances are engulfed by certain types of white blood cells, including macrophages. On engulfing the breakdown substances, the white blood cells release a powerful pyrogen called interleukin-1. This substance stimulates the secretion of a type of hormone, the prostaglandins, which in turn induces the hypothalamus to raise its temperature set point above 37 degrees. The advantage that fever provides to the body in fighting infection is unclear. Aspirin and corticosteroids are able to reduce fever by inhibiting the secretion of prostaglandins.

When the body’s ability to regulate temperature is exceeded, resulting in extreme hyperthermia or hypothermia, the results can be extremely serious. Fevers above about 41 to 42 degrees Celsius, or about 106 to 108 degrees Fahrenheit, can cause severe or fatal damage if the body temperature is not quickly lowered by treatments such as water or alcohol sponging of the skin. The high temperatures injure or kill body cells, particularly in the brain, liver, and kidneys, and cause internal bleeding. Damage to brain cells from extremely high fever is essentially irreversible and may cause permanent impairment or even death within minutes.

Hyperthermia and Hypothermia

Under some conditions, as on hot and humid days or when the body is immersed in hot water, the normal physiological reactions regulating body temperature are ineffective and body temperature may rise uncontrollably. If the air temperature rises above about 38 degrees Celsius on days in which the humidity approaches 100 percent, for example, temperature regulation by sweating and dilation of peripheral blood vessels is ineffective. Under such conditions, internal body temperature may rise to damaging levels, particularly if physical exercise is attempted. The resulting reaction, known as hyperthermia
or heat stroke, may include dizziness and abdominal distress or pain in milder cases; more severe heat stroke may produce delirium or even death. Hyperthermia differs fundamentally from fever in that the set point of the hypothalamus remains at 37 degrees. Another difference is that the circadian temperature rhythm is maintained during fever, but not in hyperthermia. In addition to high environmental heat and humidity, hyperthermia may be caused by cocaine and psychedelic drugs.

Low environmental temperatures can also exceed the body’s capacity to regulate its internal temperature. Heat loss attributable to accidental or intentional immersion in ice water, for example, induces a steady drop in internal body temperature that cannot be effectively reversed by shivering, constriction of peripheral blood vessels, or increases in chemical reaction rates. The effects of extreme cold in lowering body temperature are magnified by impairment of the regulatory function of the hypothalamus. At body temperatures below about 34 degrees Celsius, the function of the hypothalamus in temperature regulation becomes severely impaired. Shivering usually stops below 32 degrees. At internal temperatures below about 28 degrees Celsius, the temperature regulation centers of the hypothalamus cease to function entirely. Below this temperature, internal body temperature falls rapidly, breathing slows greatly or arrests, and the heart may develop an irregular beat or stop beating entirely. Death follows quickly if breathing or the heartbeat stops. Any fall of body temperature below 35 degrees is known as hypothermia.

Surgical Applications

For some surgical procedures, body temperature is deliberately reduced by administering a drug that inhibits activity of the hypothalamus. The body is then immersed in ice water or surrounded by cooling blankets until internal temperatures reach levels of 30 degrees or below. At these temperatures, the heart can be stopped temporarily without significant damage to the brain or other body tissues. Induced reduction of body temperatures in this manner is routinely used in heart surgery.

Bibliography

Berne, Robert M., and Matthew N. Levy, eds. Physiology. 5th ed. St. Louis: Mosby, 2004. Print.

Coren, Stanley. Sensation and Perception. 6th ed. Hoboken: Wiley, 2004. Print.

Guyton, Arthur C., and John E. Hall. Textbook of Medical Physiology. 12th ed. Philadelphia: Elsevier, 2010. Print.

Hertenstein, Matthew J., and Sandra Jean Weiss. The Handbook of Touch: Neuroscience, Behavioral, and Health Perspectives. New York: Springer, 2011. Print.

Schmidt-Nielsen, Knut. Animal Physiology: Adaptation and Environment. 5th ed. New York: Cambridge UP, 1998. Print.

Compare and contrast the four categories of men present in "Do Not Go Gentle Into That Good Night."

Dylan Thomas' "Do Not Go Gentle Into That Good Night" is a masterful example of the villanelle, a poetic form structured around sequences of repeating lines. In the poem, Thomas references and discusses four types of men: good men, wise men, wild men, and grave men.

The major comparison that can be made between the different types of men is that each of them experiences a major realization upon their respective death beds. The nature of these realizations, however, is different. Wise men, for instance, realize that their "words had forked no lightning" (5), and so it's suggested that wise men's wisdom is not as important in the end as it was perceived to be. In contrast, good men lament "Their frail deeds," (8) and so it seems as though they have failed to live life to the fullest. In the following stanza, wild men mourn the passing of their strength, as they "caught and sang the sun in flight/ And learned, too late, they grieved it on its way" (10). Finally, grave men enjoy the most optimistic epiphany, as they learn "Blind eyes could blaze like meteors and be gay" (14). This quote suggests that a perceived disability, such as blind eyes, is not, in the end, as debilitating as it might have been considered during life.

All in all, each type of man experiences a major insight or realization within the poem. The nature of these realizations differs, although most of them (except for the last one) seem to involve a sudden understanding about a missed or lost opportunity.  

What are the steps the nightingale takes to help the boy solve his problem?

When the nightingale hears the boy speaking of his need for a red rose, she immediately decides to help him. First of all, she flies to the centre of the grass plot to a rose tree. She asks the tree to give her a red rose but it says it cannot because it only grows white roses. On the suggestion of this tree, she flies to another but, once again, she is disappointed: this tree only grows yellow roses. There is, however, another rose tree underneath the boy's window which the nightingale flies to next.  Fortunately, this is a red rose tree but it has no flowers because of the bad weather, as it explains to the nightingale:

But the winter has chilled my veins, and the frost has nipped my buds, and the storm has broken my branches.

Undeterred, the nightingale begs for a solution and the rose tree replies that there is a way but that it is "terrible:"

All night long you must sing to me, and the thorn must pierce your heart, and your life-blood must flow into my veins.

In other words, the nightingale must sing her song while a rose thorn pierces her heart. Only when she dies will the rose tree produce the red rose which she desires. While the nightingale believes that death is a "great price to pay", she decides that the boy's love is worth such a sacrifice. That night, she perches on a branch of the rose tree and sings until the thorn pierces her heart and kills her. In return, her wish is granted and a red rose blossoms on the tree.

In Walk Two Moons, what happened to Sal's mother? What are some clues that help readers infer the ending?

It is not until Chapter 42 that the reader discovers the reason that Sal’s mother is not coming back is because she was killed in an accident. She was travelling by bus to Idaho to see her cousin when the bus swerved off the road at a sharp turn. The bus went over the edge, and the only survivor was Margaret Cadaver, who had been sitting beside Sal's mother and had become friends with her as they traveled together. Sal's mother told Margaret all about Sal and her husband. This is how Sal's father knew Margaret and talked so much with her. While Sal tried to convince herself that there was a romance brewing between Margaret and her father,in reality it was only her father clinging to the last person who had talked to his wife before her death. Margaret wanted to talk to Sal about her mother, but this was too "real" for Sal, who had not yet accepted the fact that her mother was not coming home.

There are some hints and clues, but at no time until this chapter does the reader clearly know the outcome. This is related to the fact that Sal cannot completely believe her mother is dead. The clues are clear with a second reading. Otherwise, they just seem to be random observations of Sal's. For example, in Chapter 2, Sal says that she is afraid of cars and buses, since that is how her mother was killed. In Chapter 3 she says that she is afraid of pregnant women. Sal's mother had suffered a miscarriage, which led her to want to visit her cousin in Idaho, as she was someone who knew her when she was a little girl, before she was a wife and mother. When Sal says that she needs to get to where her mother is in Idaho by her birthday so she can bring her back home, her father and grandparents tell her that she is fishing in the air because they know she is dead. When Ben asks about her mother and if she is coming back, Sal is momentarily confused. At heart, she knows her mother is gone, but she has not told anyone else about her mother's death.

When Sal’s mother left of her own free will, Sal did not understand. When Sal learns that her mother is not coming back, her father tries to tell her that she intended to come back. She did not plan to desert her family permanently, although it turned out she did. This is why Sal decides to help Phoebe find her mother, as she is convinced that if they can find Mrs. Winterbottom, it will somehow help her to deal with her own mother’s death.

What does Mr. Morrison say about the Christmas that he was six and his family died?

This conversation takes place in Chapter 7 and is a significant one. It reveals not only how horrible the violence and murders were, but also how Mr. Morrison's family was decidedly human despite being treated like they weren't.

Let's take a look at that section. Not the whole thing—it's quite long—but let's go over the most important parts.

First, after describing how two scared teenage boys had come to his family's house looking for protection against a mob of angry white people, Mr. Morrison says:

"But my daddy didn't hardly have time to finish hearing them boys' story when them devilish night men swept down."

He means the white mob coming to punish those teenage boys. Describing how the men burst into the house and start trying to kill everyone in it, not caring who, he continues:

"We warn't nothing to them. No better than dogs. Kilt babies and old women. Didn't matter."

We find out then why Mr. Morrison and his father are so physically strong:

"My folks was bred for strength like they folks and they grand- folks 'fore 'em."

What he means is that the white families who owned Mr. Morrison and his parents and grandparents purposefully "bred" their slaves to create stronger and stronger generations of them, which is good for the slave-owners because the labor can get done faster and better. It's a horrible thing that we find out: again, the slave-owners are treating the slaves like dogs (by "breeding" them).

As he concludes his story, Mr. Morrison asserts that during this attack, his parents were, as always, filled with love for the family and that this love gave them strength to fight back:

"But my mama and daddy they loved each other and they loved us children, and that Christmas they fought them demons out of hell like avenging angels of the Lord."

They lost that fight, though, and were murdered. Mr. Morrison emphasizes that he does remember that horrible event, despite being only six years old. Then he leaves.

So, from Mr. Morrison's story, we learn not only how his family was murdered and why, but also how he asserts his humanity: his family's love, strength, and unwillingness to be put down without a fight.

What are natural treatments for bed-wetting?

Introduction

Nocturnal enuresis, or bed-wetting, is defined as unintended
nighttime urination in a child who is older than five years of age. In most cases,
there is no underlying medical cause, in which case the condition is called
primary nocturnal enuresis (PNE). When enuresis occurs as a result of another
illness, it is called secondary nocturnal enuresis.

The adult bladder that becomes full during the night signals to the brain that this has occurred; in turn, the brain informs the bladder not to empty and also begins the process leading to wakefulness. The ability to carry out this process is not present at birth, but most children gradually develop this capacity and achieve it in full by age six years. However, as many as 7 percent of ten-year-olds and 1 to 2 percent of fifteen- year-olds continue to have trouble. Nearly all children with primary nocturnal enuresis will cease bed-wetting by the time they reach puberty. However, PNE remains a problem for up to 1 percent of adults.

Enuresis occurs more commonly in boys than in girls. In addition, there is a strong genetic predisposition: If both parents have enuresis, there is a 75 percent chance that a child will; this decreases to 40 percent if only one parent has enuresis.

Nocturnal enuresis is not a disease, but it can lead to significant embarrassment and limitation of activities, and for this reason treatment may be desired. The first step is a medical examination to rule out rare underlying causes, such as infection. Commonsense steps follow, such as not drinking much liquid near bedtime and urinating just before going to bed. More specific treatment can be delayed as long as desired, because in the great majority of cases, nocturnal enuresis will eventually disappear. For older children who wish to accelerate the process, nighttime alarm systems that wake the child in response to moisture in the child’s underwear are often highly effective. Other methods include bladder exercises and a schedule of planned nighttime waking. If these behavioral methods fail, the use of various medications may be considered.

Proposed Natural Treatments

Many parents turn to alternative medicine for the treatment of nocturnal enuresis if behavioral methods do not work. However, no alternative therapies have been proven effective for this condition.

Hypnosis has shown some promise for nocturnal enuresis. In
one study, fifty children were given the drug imipramine or given hypnotherapy
for three months. The results showed substantial and approximately equal benefits
in the two groups. Subsequently, children in the hypnosis group practiced
self-hypnosis for another six months, while those in the imipramine group did not
utilize any special therapy. At the end of the six months, children practicing
self-hypnosis had maintained their benefits to a much greater extent than those in
the imipramine group. Other studies found benefits with hypnosis too; however,
these studies had significant design limitations. Overall, the evidence supporting
hypnosis for nocturnal enuresis is not strong.

It has been suggested that food allergies may play a role in
nocturnal enuresis. However, there is only incomplete evidence that allergen
avoidance or any other dietary approaches can help.

Herbs used for miscellaneous bladder problems are often recommended for nocturnal enuresis, on general principles. These herbs include juniper, lobelia, marshmallow root, parsley root, and uva ursi. However, there is no evidence that these herbs help the condition, and some, such as uva ursi, may have toxic properties, especially when given for the long term.

Acupuncture, bach flower remedies, and Chinese
herbal medicine are also sometimes recommended for nocturnal enuresis, but there
is no reliable evidence that they are effective. One reasonably well-designed
study found evidence that a special form of chiropractic
(the activator technique) is not effective for bed-wetting. A small preliminary
study suggested that the use of pulsed magnetic stimulation day and night for two
months may be helpful in girls.

Herbs and Supplements to Use Only with Caution

Various herbs and supplements may interact adversely with drugs used to treat nocturnal enuresis, so persons should be cautious when considering the use of herbs and supplements.

Bibliography

Banerjee, S., A. Srivastav, and B. M. Palan. “Hypnosis and Self-Hypnosis in the Management of Nocturnal Enuresis: A Comparative Study with Imipramine Therapy.” American Journal of Clinical Hypnosis 36 (1993): 113-119.

But, I., and N. M. Varda. “Functional Magnetic Stimulation: A New Method for the Treatment of Girls with Primary Nocturnal Enuresis?” Journal of Pediatric Urology 2 (2006): 415-418.

Egger, J., et al. “Effect of Diet Treatment on Enuresis in Children with Migraine or Hyperkinetic Behavior.” Clinical Pediatrics 31 (1992): 302-307.

Mellon, M. W., and M. L. McGrath. “Empirically Supported Treatments in Pediatric Psychology: Nocturnal Enuresis.” Journal of Pediatric Psychology 25 (2000): 193-214.

Reed, W. R., et al. “Chiropractic Management of Primary Nocturnal Enuresis.” Journal of Manipulative and Physiological Therapeutics 17 (1994): 596-600.

Why is Hamlet unhappy?

Shakespeare’s Hamlet unfolds with a melancholy environment, as the young Hamlet enters the stage troubled by the recent death of his father and marriage of his mother to his uncle Claudius.  Hamlet is greatly perturbed by the events as conveyed in his first exchange with Claudius:

Claudius: But now, my cousin Hamlet, and my son—
Hamlet: (aside) A little more than kin and less than kind.
Claudius: How is it that the clouds still hang on you?
Hamlet: Not so, my lord.  I am too much i’ the sun. (I. ii. 64-67)

In this exchange, Claudius refers to Hamlet as both cousin and son, which angers Hamlet. Hamlet says that Claudius is now “more than kin,” as he is now his stepfather, but quickly adds that Claudius is “less than kind.”  This is in part due to the fact that Claudius has so hastily married Gertrude, as Hamlet points out, “The funeral baked meats / Did coldly furnish forth the marriage tables” (I. ii. 179-180). 

Indeed, the death of his father and remarriage of his mother have a great effect on Hamlet, and he spends the majority of the play consumed with grief.  He explains:

'Tis not alone my inky cloak, good mother,
Nor customary suits of solemn black,
Nor windy suspiration of forced breath,
No, nor the fruitful river in the eye,
Nor the dejected 'havior of the visage,
Together with all forms, moods, shapes of grief,
That can denote me truly. These indeed “seem,”
For they are actions that a man might play.
But I have that within which passeth show,
These but the trappings and the suits of woe. (I. ii. 77-86)

In this passage, Hamlet explains that his mourning, dark clothes, weeping and sighs are just surface expressions of the true grief he feels.  He is truly angered and upset about his father’s death and mother’s hasty remarriage. He goes on to state, “Within a month, / Ere yet the salt of most unrighteous tears / Had left the flushing her galled eyes, / She married” (I. ii. 154-57).  In this hyperbole, Hamlet claims that his mother remarried before her tears over her husband’s death even dried.  He then states, “It is not nor it cannot come to good, / But break, my heart, for I must hold my tongue” (I. ii. 159-60).  Thus, Hamlet is unhappy because not only has his father died and his mother married his uncle, he cannot adequately express his melancholy or objection.  He therefore spends his time wandering around the castle in mourning clothes, contemplating the death of his great father and loathing the fact that his mother has so readily remarried.

How does Duncan reward Macbeth for his bravery in defeating the rebels?

King Duncan rewards Macbeth's bravery with a promotion.

In Act I scene ii, a "bloody sergeant" tells King Duncan that Macbeth bravely slew Macdonwald, the leader of the rebels, by slicing him from navel to chin and beheading him: "Till he unseam'd him from the nave to the chaps, / And fix'd his head upon our battlements." Unseamed means cut open; from the nave to the chaps means from the navel to the chin; fixed his head means stuck his head; upon our battlements means on our fort's wall.

Later in the same scene, the Thane of Ross shows up and informs the king that the Thane of Cawdor is a traitor and was helping the rebels: "Assisted by that most disloyal traitor / The Thane of Cawdor...." The scene concludes with Duncan telling Ross to execute the traitor and give his title, Thane of Cawdor, to Macbeth.

This is how Macbeth realizes that the three witches' prophesy is true and later decides to kill the king. In Act I scene iii, The three witches meet Macbeth and Banquo on the battlefield and tell Macbeth that he will be Thane of Cawdor and then King of Scotland:

FIRST WITCH: All hail, Macbeth! hail to thee, Thane of Glamis!

SECOND WITCH: All hail, Macbeth! hail to thee, Thane of
Cawdor!

THIRD WITCH: All hail, Macbeth, that shalt be King hereafter!

Macbeth is currently the Thane of Glamis, but he does not believe he will become Thane of Cawdor and then king: "...to be King / Stands not within the prospect of belief, / No more than to be Cawdor" until he is informed that he has been promoted to Thane of Cawdor. In a way and without knowing it, by promoting Macbeth King Duncan has started the chain of events that will lead to his own death.

Who made up the "good guys" during the Cold War?

The answer to this question depends on which perspective you are viewing this question. If you are looking at it from the viewpoint of an average American citizen living during the Cold War, you would say the leaders of the United States, Great Britain, France, and most other countries that had a democratic government would be considered as the good guys. From this perspective, you would see the leaders of these countries fighting to stop the spread of a system that limited the freedom of the people they ruled both politically and economically in a positive light.

If you are viewing this from the perspective of an average person who lived in China or in the Soviet Union during the Cold War, you would say the leaders of the countries that had a communist system of government were the good guys. From this perspective, these leaders were working to stop the spread of an economic system that had much inequality in it. There were very rich people and very poor people in the capitalist system. The people who lived in these communist countries viewed our system as an aggressive system trying to disrupt their way of living.

The answer to this question depends on one’s perspective.

Do silver nitrate and potassium phosphate form a precipitate when mixed together?

When silver nitrate and potassium phosphate are combined, they form a double replacement reaction. In a double replacement reaction, the ions 'switch partners.' The balanced chemical reaction between silver nitrate and potassium phosphate is as follows:

3AgNO3(aq) + K3PO4(aq) -> Ag3PO4(s) + 3KNO3(aq)

The product silver phosphate is a precipitate as indicated by the (s) for solid. In order to determine if a reaction will form a precipitate or not, you need to refer to the solubility rules. From the solubility rules, you can find that silver phosphate will form a precipitate because there is a rule that states that all phosphates are insoluble, except for those with NH4 or with alkali metals. This explains why in the reactants, K3PO4 is soluble, because potassium is an alkali metal in group 1. Silver, however, is not an alkali metal, so the product silver phosphate will form a precipitate.

When determining if a precipitate will be formed, you will often be asked to write a net ionic equation which shows the ions that combine to form the precipitate. For this equation, the net ionic equation is:

3 Ag+(aq) + PO4 3–(aq) → Ag3PO4(s)

The reference link below contains a good explanation of all of the solubility rules you will need to solve other precipitate problems.

I would like to know which programming language is best to learn for building website. I'm a beginner student of management so I don't know...

There are a few languages that you will want to learn in order to develop web pages. The first two are not programming languages but, rather, could be considered formatting languages. These would be Hypertext Markup Language (HTML) and Cascading Style Sheets (CSS). These two languages allow you to create and format content. HTML lets you develop information that would be unique to each page on your site and CSS allows you to create unifying features that carry across all your pages. 

While you can create websites just using these two languages, if you want your page to look like it was created somewhere after 1998, you will need to learn some programming languages. These languages allow you to give your webpage functionality. Javascript is a flexible language that allows you to create buttons that your readers can push as well as certain kinds of graphics and animation. PHP allows you to work with data that users input in order to generate webpages geared toward user needs and interests. 

What is the resolution in the book Angels and Demons?

At the end of Angels and Demons, Robert Langdon awakens in a hospital and watches on Kohler's camera a video of the late pope's assistant branding himself with the sign of the Illuminati and confessing that he had killed the pope for having an illegitimate child. Langdon, Vittoria, and the cardinals return to the Vatican to confront the camerlengo and learn that he had misheard the Pope saying he had fathered a child through artificial insemination. The camerlengo also confesses that he hired Vetra's assassin, coordinated the stealing of the antimatter, and faked his vision from God. The Illuminati involvement was also feigned, and the entire plot was intended to unite the Catholic church. He then lights himself on fire in St. Peter's Square. Shortly after, Mortati is elected Pope by the cardinals. The story ends with Langdon and Vittoria on a date at Hotel Bermini.

In Shakespeare's Romeo and Juliet, what insults does Juliet use to describe Romeo after he has killed Tybalt?

In Act III, Scene 2, Juliet is at first confused by the Nurse's report of the events which take place in the preceding scene. For a time, Juliet believes that maybe Romeo is dead but soon learns the truth. Tybalt is dead and Romeo banished. Obviously her feelings are mixed. She was apparently close to Tybalt and takes out her anger in a series of contradictory insults against Romeo. In lines 75-84, she uses several oxymorons to describe Romeo. She refers to him as "Beautiful tyrant!," "Fiend angelical!," "Dove-feathered raven!," "Wolfish-ravening lamb!," "damned saint" and "honorable villain!" These descriptions display the polarity of her mind. She cannot fathom that her beloved Romeo would have actually killed a member of her family. She considers him perfect and cannot wed her conception of him with the violence he is apparently guilty of. 

A little later in the scene, she again labels him a villain, but also begins to reconcile herself with the fact that it was either Romeo or Tybalt who would have turned up dead. She says,

My husband lives, that Tybalt would have slain,
And Tybalt’s dead, that would have slain my husband.
All this is comfort. Wherefore weep I then?

By the end of the scene, she has retained her loyalty to Romeo and sends the Nurse to retrieve him from Friar Lawrence's cell so that they can consummate their marriage.

What is thirst motivation?

Introduction

The range of human motivation is quite broad in controlling behaviors. Motivation can be defined as a condition that energizes and directs behavior in a particular manner. Different aspects of motivation can be attributed to instinctive behavior patterns, the need to reduce drives, or learned experiences.

Thirst is one of many biologically based motivational factors; among other such factors are those that involve food, air, sleep, temperature regulation, and pain avoidance. Biologically based motivational factors help humans and other organisms to maintain a balanced internal environment. This is the process of homeostasis. Deviations from the norm, such as hunger, excessive water loss, and pain, will cause an organism to seek out whatever is lacking.

Biologically based motivational factors, such as thirst, have been explained by the drive-reduction theory (drive theories) proposed by Clark L. Hull
in 1943. The lack of some factor, such as water or food, causes the body to feel unpleasant. This is turn motivates one to reduce this feeling of unpleasantness, thus reducing the drive. Thirst is considered what is called a primary drive. Primary drives, which are related to biologically based needs such as hunger, thirst, and sleepiness, energize and motivate one to fulfill these biological needs, thus helping the body to maintain homeostasis. Secondary drives fulfill no biological need.

One may wonder what it is that makes one thirsty and how one knows when one has had enough to drink. Seventy-five percent of a human’s weight is water. The maintenance of water balance is an ongoing process. In an average day, a person will lose approximately 2.5 liters of water; 60 percent of the water loss occurs through urination, 20 percent is lost through perspiration, and the remainder is lost through defecation and exhalation from the lungs. These 2.5 liters of water must be replaced.

What is the stimulus that motivates one to drink when one is thirsty? The simplest hypothesis, which was proposed by Walter Bradford Cannon
in 1934, is the dry mouth hypothesis. According to Cannon, it is a dry mouth that causes one to drink, not the need for water. This hypothesis has not held up under scrutiny. Research has shown that neither the removal of the salivary glands nor the presence of excess salivation in dogs disrupts the animals’ regulation of water intake. Studies have indicated that the amount of water consumed is somehow measured and related to the organism’s water deficit. This occurs even before the water has been replaced in the person’s tissues and cells. Thus, dry mouth is a symptom of the need for water.

Water Regulation Process

When a human being’s water intake is lower than its level of water loss, two bodily processes are set in motion. First, the person becomes thirsty and drinks water (provided it is available). Second, the kidneys start to retain water by reabsorbing it and concentrating the urine. Thus, the kidneys can conserve the water that is already in the body. These processes are set in motion by the central nervous system (CNS).

The CNS responds to two primary internal bodily mechanisms. One is cellular dehydration thirst, and the other is hypovolemic thirst (a change in the volume of water in the body). To understand these mechanisms, one must realize that the body contains two main supplies of water. One supply, the intracellular fluid, is in the cells; the other supply consists of the extracellular fluid surrounding the cells and tissues and the fluid in the circulatory system. Water moves between these two areas by means of a process called osmosis, which causes it to move from an area of higher concentration to an area of lower concentration.

A person who is deprived of water will experience cellular dehydration thirst as a result of water loss caused by perspiration and excretion through the urine. This increases the salt concentration in the extracellular fluid, thereby lowering the water concentration. Thus, the cells lose their water to the surrounding extracellular fluid. The increasing salt concentration triggers specialized osmoreceptors located in the hypothalamic region of the brain. Two events occur: First, drinking is stimulated; second, antidiuretic hormone (ADH) is secreted from the pituitary gland in the brain. The ADH helps to promote the reabsorption of water into the kidneys.

The second kind of thirst, hypovolemic thirst, occurs when there is a decrease in the volume of the extracellular fluid as a result of bleeding, diarrhea, or vomiting. This produces a decrease in the salt concentration of the extracellular fluid, which lowers the blood pressure, which in turn stimulates the kidney cells to release a chemical. Eventually, the thirst receptors in the hypothalamus are stimulated; these cause the organism to consume water. In addition, ADH is secreted in this process, which promotes the conservation of water.

The regulation of water intake in humans is thus related to a number of factors and is quite complex. Though cellular dehydration thirst and hypovolemic thirst play a role, it appears that in humans, peripheral factors such as dry mouth play an even larger role. Humans can drink rapidly, replacing a twenty-four-hour water deficit in two to three minutes. This occurs even before the cellular fluid has replaced the water, which takes approximately eight to twelve minutes.

Motivational Factor

Thirst is a strong motivational factor. The importance of replacing lost water is underscored by the fact that a person can survive for a month without food but for only several days without water. It appears that both thirst processes help to promote drinking. Researchers have estimated that 64 to 85 percent of the drinking following water loss is caused by cellular dehydration thirst. Hypovolemic thirst accounts for 5 to 27 percent of the drinking, and the remainder is caused by peripheral factors.

The two types of thirst are independent of each other. The receptors for both thirsts are located in the hypothalamic region of the brain, but they are at different locations. Research has shown that lesions in one region will have no effect on thirst regulation in the other region.

Although the motivation to drink in humans is under conscious control by peripheral factors, unconscious control does exert a large influence. A study of cellular dehydration thirst using goats showed that the injection of a saline solution that has a salt concentration of more than 0.9 percent salt (body fluids have a salt concentration of 0.9 percent salt) into the area in which the osmoreceptors are located will produce a drinking response within sixty seconds. Similar results have been found regarding hypovolemic thirst; injecting angiotensin II (a converted protein found in the blood) into the hypothalamus causes a drinking response. This occurs even in animals that are fully hydrated. These animals will consume in direct proportion to the amount of angiotensin II injected into the hypothalamus.

Diet can have a profound effect on water balance in humans. Eating salty foods will produce cellular dehydration thirst despite adequate fluid levels, because water will flow out of the cells into the extracellular fluid. In contrast, salt-free diets will produce hypovolemic thirst by causing water to flow into the cells. Other factors also cause thirst. As stated previously, diarrhea, vomiting, and blood loss will cause hypovolemic thirst as a result of the loss of extracellular fluid. Therefore, significant blood loss will cause a person to become thirsty.

Impact of Diseases

Diseases can also have an impact on thirst. An interesting example of such a disease is diabetes. Diabetes is a condition in which the body cannot process blood glucose (a type of sugar) properly. Improper diet or medication can cause diabetic ketoacidosis, which causes the levels of glucose and ketone bodies (derivatives from fat) in the blood to rise. This creates a major shift in the water balance of the body. Water leaves the cells and enters the blood system, causing the volume of blood to increase. This extra fluid (along with potassium and sodium) is excreted from the body in the urine, which causes the body to suffer dehydration and triggers a tremendous thirst. Since fluid is lost from both cells and extracellular fluid, this causes both types of thirst. Excessive thirst is still a symptom of diabetes, but it has become rare as a result of education and improved treatment.

Impact of Exercise

Thirst motivation also operates during exercise. In short-term exercise, thirst motivation does not come into play because the body usually maintains its temperature. During long-term exercise, however, water intake at intervals facilitates athletic performance by helping to maintain body temperature. The motivation to drink occurs as a result of sweating, which causes the salt concentration in the body to rise during exercise, thereby causing cellular dehydration thirst. Interestingly, voluntary thirst and peripheral factors do not motivate one to take in water during prolonged exercise in the heat until it is too late. Thus, coaches should insist that athletes drink water as they perform.

Bibliography

Carlson, Neil R. Foundations of Physiological Psychology. 7th ed. Boston: Allyn, 2008. Print.

Deckers, Lambert. Motivation: Biological, Psychological, and Environmental. 4th ed. Boston: Pearson, 2014. Print.

Levinthal, Charles F. “Chemical Senses and the Mechanisms for Eating and Drinking.” Introduction to Physiological Psychology. 3rd ed. Englewood Cliffs: Prentice, 1990. Print.

Mader, Sylvia S. Biology. 11th ed. Boston: McGraw, 2013. Print.

Wagner, Hugh. The Psychobiology of Human Motivation. Hoboken: Taylor, 2014. Digital file.