What was the effect of Hoover's philosophy on the U.S. during he Great Depression?

Hoover's philosophy is usually (if rather simplistically) called "rugged individualism," based on a speech he gave while running for President. What he meant was that government policies needed to incentivize initiative and hard work. What he did not mean, as he stated categorically in his speech, was a return to laissez-faire policies of the late nineteenth century. Once the Depression broke out, Hoover advocated what he called "associationism," the mutual agreement of business leaders to act in the interest of the country. He also advocated significant and really unprecedented levels of government aid in the form of loans to businesses (the Reconstruction Finance Act) and public works (like the Hoover Dam). So Hoover did not take the "hands-off" approach to the Depression that he is often blamed for taking. However, he strongly opposed direct aid, a position that made him seem unfeeling and insensitive to the suffering of many Americans. He also generally refused to use the coercive power of the state to force businesses to cooperate in the ways he thought necessary. Finally, he reluctantly signed off on protectionist legislation, a disastrous decision that stemmed from his views on monetary policy. So Hoover, who was one of the nation's leading humanitarians before the Depression, assumed much of the blame for the government's apparently feckless response to the economic catastrophe. This fact, while perhaps unfair, stemmed from his adherence to certain philosophical principles in the face of an unprecedented disaster. It also, to a degree still debated by historians, contributed to the human impact of the Depression.

How should teachers deal with fatigue in the classroom?

One part of dealing with fatigue in the classroom is helping teachers feel more energized. To this end, researchers such as Sapienza, Crandell, and Curtis have examined the use of sound-field frequency modulation (FM) amplification in the classroom to lessen the strain on teachers' voices. The data have supported the use of FM amplification to lessen teachers' voice fatigue. (Please the NIH link below.)

To deal with student fatigue, studies such as that done by Dowson called "Do children learn better in the morning or afternoon?" (see the link below) suggest that some students, such as teenagers, actually learn better in the afternoon. Their circadian rhythms fall in the morning and from 3-5pm in the afternoon, and they are most alert in the later morning and early afternoon, so harder lessons should be planned for this time. 

In addition, students who are more interested in what they are learning tend to be more alert, according to research done by Berto et al. (2009). This research was published in an article called "An exploratory study of the effect of high and low fascination environments on attentional fatigue" (see the link below). Students can remember more when they rate subjects as highly fascinating, so teachers need to build elements into their lessons that are likely to catch students' attention and keep it. That means avoiding repetition or predictable lessons. 

What is the liver?

Structure and Functions

The liver, an accessory gland of the digestive system, is the largest organ in the human body. Located in the upper-right quadrant of the abdominal cavity, it abuts the diaphragm on the anterior surface. The liver is composed of two lobes of unequal size, with the large right lobe further divided into two smaller lobes. The organ is protected by the ribs, which cover nearly the entire surface. The liver contains only one type of functional cell, known as a hepatocyte. Closely associated with the organ is the gallbladder, a saclike structure that holds bile, a product of the hepatocytes. Bile is continually produced by the hepatocytes but is stored in the gallbladder until it is required for digestive products.

The liver is unique in that it receives blood from two different sources. The hepatic artery delivers blood to the liver from the systemic circulation. The liver also receives blood via the portal vein, which collects blood that has previously passed through the small intestine and has absorbed nutrients from the digestive system. As the blood enters the liver, it flows into dilated capillaries called sinusoids. Blood flow through sinusoids is much slower than through capillaries, and the exchange of materials between hepatocytes and the bloodstream is accomplished with little difficulty. This slower process also allows the liver to serve as a storage organ for blood, which gives the organ its characteristic dark red appearance.

The liver is essential to the normal functioning of the body. Its activities are many and varied: It regulates the metabolism of carbohydrates, lipids, and proteins; synthesizes proteins, particularly those of blood plasma that control clotting; serves as a storage site for some vitamins and iron; degrades steroid hormones; and inactivates and/or excretes certain drugs and toxins.

The liver plays a major role in carbohydrate metabolism. As
carbohydrates are absorbed from the small intestine, they are transported to the liver through the portal vein. The liver regulates blood sugar levels by removing excess quantities. If the diet includes too much glucose, this substance is stored in the liver or skeletal muscle as glycogen. If the blood sugar levels are low, the glycogen is broken down into glucose and released to the bloodstream. The liver is also capable of converting amino acids, lipids, or simple carbohydrates into glucose.

The principal functions of the liver in lipid metabolism are twofold. First, it is responsible for the breakdown of large fat molecules into small compounds that can be used for energy. Second, it synthesizes triglycerides, cholesterol, and phospholipids from other fats. All three of these compounds play important roles in cellular function.

The synthesis of proteins by the liver is of major importance for the body. The liver is capable of synthesizing not only a variety of proteins but also the nonessential amino acids that are the building blocks of proteins. Many of the proteins that the liver synthesizes are found in blood plasma, including those factors responsible for blood clotting. To protect the body against deficiencies in these substances, the liver stores vitamins A, D, and B12. It is also capable of storing iron, the mineral necessary for the production of hemoglobin.

Located in the smooth endoplasmic reticulum of hepatocytes are nonspecific enzymes called the mixed-function oxidases. They are capable of metabolizing a wide variety of hormones, including some polypeptide hormones and the steroid hormones, such as cortisol, estrogen, and testosterone. These same enzymes are responsible for the degradation of many foreign substances that enter the body, such as prescription medications, illegal drugs, and toxins. Most of the materials metabolized are made more water-soluble, and therefore more easily excreted, by the kidney. Others are removed from the hepatocytes in the bile that the cells produce.

Production of bile by the hepatocytes is of utmost importance to the digestive system. Bile is composed of lecithin, cholesterol, bile pigments, proteins, and bile acids, along with an isotonic solution similar to blood plasma. Bile is produced continually and stored in the gallbladder. Several minutes after a meal begins, the gallbladder releases bile to the duodenum of the small intestine. The highest rate of bile release occurs during the duodenal
digestion of food and is controlled by the hormone cholecystokinin. In the duodenum, bile acts as an emulsifier of fat in the diet. It breaks large lipid droplets into many small lipid droplets, which can more easily be digested by enzymes in the small intestine. About 95 percent of the bile is reabsorbed and returned to the liver, and the other 5 percent is excreted with the feces. This provides one mechanism for the body to use the digestive system for the removal of waste products. One important product that is excreted in this
manner is bilirubin, a by-product of the normal destruction of old red blood cells.

Disorders and Diseases

The liver is unique among body organs because it has the ability to regenerate in cases of injury or disease. It is estimated that in a young, healthy individual a liver that has suffered a physical injury could regenerate as much as 80 percent of the total organ. Many important organs are paired, such as the lungs and kidneys. Though the liver is a single organ, its ability to regenerate ensures normal function even in cases of severe injury.

The presence of liver disease is detectable in many ways. With some diseases, the liver becomes enlarged and can be felt below the ribs. This swelling may be associated with localized discomfort or pain in the region. In more severe cases of liver disease, the organ may actually shrink and recede further under the ribs, a condition easily detected by a physician.

The pathophysiology of the liver is characterized by certain physiologic events that occur regardless of the underlying cause. Within the liver, disease may result in portal hypertension, blockage of bile ducts, and cellular injury or death. Cellular injury may be manifest by fatty infiltration and by interference with cellular functions, including the synthesis of proteins necessary for blood clotting, the metabolism of drugs or toxins, the regulation of glucose, and the production of bile. Any or all of these physiologic changes can lead to effects in other parts of the body.

Disease of the liver is often detectable by routine blood tests that include liver function tests. The patient may show decreased levels in the blood serum of proteins that are normally produced by the liver, an increased blood-clotting time, or increased serum levels of enzymes that are normally found only in the liver. A yellow skin tone known as
jaundice has been associated with liver disease. This discoloration of skin and the sclera of the eye is a result of excessively high levels of bilirubin in the blood. Bilirubin is a by-product of the breakdown of red blood cells that are near the end of their 120-day life cycle.

The injury or death of liver cells may present a pathology unique to the liver, the disease cirrhosis. When hepatocytes are injured or diseased, they begin to accumulate lipids in vacuoles, giving the liver a whitish appearance. Associated with the development of a fatty liver, the cells may divide to produce more cells that will ensure normal function. Sometimes, however, this stimulation of cell division leads to an excess of hepatocytes, a condition that may result in abnormal patterns of blood flow through the liver. In addition, this phenomenon may include the production of large nodules of connective tissue to replace dead or dying cells, a condition comparable to scarring. The development of scars may cause increased blood pressure in the portal veins and may block bile ducts. Cirrhosis may be caused by a variety of conditions, including alcoholism, exposure to toxic substances, or infection. It
is irreversible and ultimately causes the death of the patient.

Diseases of the liver can be classified according to the following scheme: congenital liver disorders, viral and nonviral infections, drug-induced and toxin-induced disease, vascular disorders, metabolic disorders, iron accumulation, alcoholic liver disease, and tumors.

The most common types of congenital diseases of the liver involve abnormalities of the bile ducts or of the portal vein, which may be associated with portal hypertension. More important, however, are those diseases that lead to the formation of cysts, such as polycystic liver disease or hepatic fibrosis. Jaundice of the newborn, a discoloration of the skin at birth, usually clears within a week or so with no long-term effects.

Viral infections of the liver may be associated with the hepatitis viruses or other viruses less specific for the liver. The four most common hepatitis viruses are hepatitis A, hepatitis B, hepatitis C, and hepatitis D. Hepatitis can also be associated with yellow fever, infectious mononucleosis, cytomegalovirus infection, and herpes simplex.

Hepatitis A is also known as infectious hepatitis. It is generally transmitted via fecal contamination of milk, water, or seafood. It is most common in the areas of the world where untreated sewage may come into contact with the water supply or food sources. It has a short incubation period and is usually not fatal; it does not lead to chronic hepatitis. Hepatitis B, also known as serum hepatitis, is transmitted from persons with an active form of the disease or from carriers via contaminated blood or blood products. It is particularly prevalent among drug users who share needles. The threat of contraction of hepatitis B from a transfusion has been greatly reduced by the screening of blood products. Hepatitis B has a long incubation period, up to six months. The severity of the disease varies greatly from subclinical hepatitis (showing no symptoms) to chronic hepatitis and in some cases may result in death. The course of hepatitis C disease resembles that of hepatitis B and may lead to chronic hepatitis. Hepatitis D is believed to be a defective virus that is found only in the presence of hepatitis B. It is transmitted via the same route and can result in chronic hepatitis.

Hepatitis from any cause may show subclinical or mild, influenza-like symptoms. Acute hepatitis may cause loss of appetite, vomiting, fever, jaundice, and enlargement of the liver. The viruses that cause hepatitis replicate within the liver cells, which could be the cause of the injury to these cells. Hepatocyte injury could also be a result of the immune system’s attempt to fight the virus, which may injure the cells of the liver in the process. In either case, the damaged cells swell before they die. The liver can also be infected by bacterial cells, which usually reach the liver as a result of a systemic infection.

Many toxins or drugs can injure the liver, in a general pattern that is similar to the effects of infectious agents. The assault on the cell often leads to fatty infiltration, followed by swelling and finally by the death of the hepatocyte. Even in less severe cases of injury, those that do not lead to death of the hepatocyte, there is often impairment of the metabolic activities of the liver that can lead to diverse systemic effects. One of these effects is the ability to metabolize foreign compounds or naturally occurring steroids; the accumulation of these compounds throughout the body can have wide-ranging consequences.

The liver is adversely affected by the constant intake of excessive quantities of ethyl alcohol. In the early stages of alcoholism, the physiologic changes may be a result of improper nutrition or of vitamin deficiencies. During the more advanced stages of alcoholism, the patient is likely to suffer from a fatty liver and, ultimately, from cirrhosis. While those who stop drinking may slow down the advancement of cirrhosis, the disease appears to be irreversible.

There are more than five thousand metabolic enzymes in the liver, each of which is controlled genetically. Important in the treatment of metabolic disease is early diagnosis, which may prevent damage to other organs or to the liver. Dietary control may be used to minimize the effects of such conditions, leading to a near-normal life. Examples of treatable metabolic diseases are galactosemia, a condition that prevents the conversion of galactose to glucose; fructosemia, a condition that leads to the accumulation of fructose-1-phosphate; and Wilson disease, an accumulation of copper in vital organs as a result of a defect in copper metabolism. In each case, the accumulation of a certain substance can lead to cellular damage, but dietary control of the substance can minimize the effects. Hemochromatosis is a similar disease that leads to accumulation of iron in the liver. As with Wilson disease, the deposition of this element is not limited to the liver and can accumulate in other vital tissues of the body as well.

Cancer of the liver
is usually caused by its spread from another site. Primary liver cancers are rare and usually do not occur until late in life. Risk factors may include exposure to hepatotoxins, chronic liver disease, or hepatitis B. There are two types of primary carcinomas of the liver: hepatocellular carcinoma, which develops in hepatocytes, and cholangiocellular carcinoma, which develops in bile ducts.

Perspective and Prospects

The liver is a vital organ that plays a major role in the homeostasis of the body. Any condition that adversely influences the liver will have wide-ranging effects on other organs and the patient as a whole.

Because one of its functions is the metabolism of pollutants, drugs (including alcohol), and hormones, the liver is often exposed to substances that are toxic to its hepatocytes. When these compounds are encountered, the liver efficiently alters them for excretion. Sometimes, however, these substances may do damage to the cells before the liver can metabolize them.

When a liver cell is injured, the end result may be the death of the cell. Fortunately, liver cells are efficient at cell division and can replace those cells that have been injured or that have died. With continued damage to liver cells, however, the body can no longer replace them, and the resulting decrease in liver function leads to extensive complications throughout the body. A decrease in liver function will not only have an effect on the digestive system but will have wide-ranging effects on glucose and lipid metabolism (normal functions of the blood whose proteins are synthesized by the liver) and on the ability to remove certain foreign substances or toxins from the blood. For example, if the ability to metabolize medication is impaired by liver disease, the patient’s body may accumulate high, even toxic, levels of drugs. These substances can have pronounced effects, particularly on the nervous system. With liver injury, the once-simple act of determining a medication dosage can become a critical problem.

Despite the liver’s regenerative capacity, liver injury or disease can have permanent effects. However, some conditions previously thought incurable, such as chronic hepatitis B and C, can now be treated successfully in many cases with antiviral drugs and interferon. The medical community can treat the symptoms of hepatitis.

Cancer of the liver
is also difficult to treat. Because it is not easily detected, the diagnosis is rarely early. Unless the cancer is restricted to one lobe that can be removed, surgery is rarely the answer. Treatment is further complicated by the fact that the liver cells are particularly sensitive to radiation and that the doses needed to treat the cancer would be deadly to hepatocytes. Chemotherapy has been the mainstay of treatment for both metastatic and primary liver cancer, but transplantation is increasingly recommended for patients with primary liver cancer.

With the discovery of immunosuppressive drugs,
liver transplantation has become a positive procedure in the treatment of liver disease, and the results are promising. The availability of healthy livers for transplant, however, makes this an option limited to a small percentage of patients.

Bibliography

Chandrasoma, Parakrama, and Clive R. Taylor. Concise Pathology. 3d ed. Stamford, Conn.: Appleton & Lange, 1998.

Clavien, Pierre-Alain, et al. Malignant Liver Tumors: Current and Emerging Therapies. 3d ed. Hoboken, NJ: Wiley-Blackwell, 2010.

Dollinger, Malin, et al. Everyone’s Guide to Cancer Therapy. 5th ed. Kansas City, Mo.: Andrews McMeel, 2008.

Feldman, Mark, Lawrence S. Friedman, and Lawrence J. Brandt, eds. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease: Pathophysiology, Diagnosis, Management. New ed. 2 vols. Philadelphia: Saunders/Elsevier, 2010.

Guyton, Arthur C., and John E. Hall. Guyton and Hall Textbook of Medical Physiology. 12th ed. Philadelphia: Saunders/Elsevier, 2011.

McCance, Kathryn L., and Sue M. Huether. Pathophysiology: The Biologic Basis for Disease in Adults and Children. 6th ed. St. Louis, Mo.: Mosby/Elsevier, 2010.

Reau, Nancy, and Fred Poordad. Primary Liver Cancer: Surveillance, Diagnosis, and Treatment. New York: Humana Press, 2012.

Scanlon, Valerie, and Tina Sanders. Essentials of Anatomy and Physiology. 6th ed. Philadelphia: F. A. Davis, 2012.

Schiff, Eugene R., et al. Schiff's Diseases of the Liver. 11th ed. New York: John Wiley & Sons, 2012.

How does substance abuse affect celebrities?

Substance Abuse Prevalence

Although there have been no scientific studies of how often addictions
occur among celebrities, popular news sources frequently report celebrity arrests for drunk driving, drug possession, public intoxication, and other criminal offenses related to substance abuse. Many celebrities and public figures, including Betty Ford, Elizabeth Taylor, Melanie Griffith, Drew Barrymore, Keith Urban, Eminem, and Ben Affleck, to name just a few, have openly shared their personal stories of struggle with addictions in interviews and autobiographies.

Substance abuse also has been linked to the deaths of many celebrities. Whitney Houston, Michael Jackson, Amy Winehouse, Elvis Presley, Dorothy Dandridge, Marilyn Monroe, John Belushi, Anna Nicole Smith, Janice Joplin, and Heath Ledger are a few examples of celebrities whose deaths involved drug or alcohol overdoses or otherwise harmful combinations of legal and illegal substances.

Other celebrities, such as Lindsay Lohan, Mel Gibson, Robert Downey Jr., and Charlie Sheen, have been in the public eye because of their addictions and substance-abuse-related behaviors. One television reality show, Celebrity Rehab with Dr. Drew (which aired from 2008 to 2012), documented the lives of celebrities seeking inpatient hospital treatment for a variety of addictions. The show ended after its sixth season following the death of a fifth former cast member.

Possible Causes

By the nature of their work, celebrities are subject to public attention and scrutiny. Often, this attention and scrutiny extends beyond celebrities’ work into their personal lives. In 1972 psychologists Thomas Duval and Robert Wicklund proposed self-awareness theory, a framework that may explain why some celebrities abuse substances to cope with excessive attention.

According to self-awareness theory, when persons engage in activities that draw attention to themselves, they often evaluate themselves negatively because their actual lives do not live up to some high internal standard. When this happens, these persons are likely to experience a drop in self-esteem. Researchers who tested self-awareness theory found that people who are more self-focused, as many celebrities can be, are at increased risk for depression, anxiety, and substance abuse. Persons with higher degrees of self-focus also are more likely to have long-lasting negative moods. People may cope with this discomfort by trying to behave in ways that match their internal standards, or they may look for ways to avoid or escape a focus on the self. Some of these escapes include substance use, gambling, sex, shopping, and other addictive behaviors.

Psychologists Jay Hull and Richard Young documented this phenomenon in a 1983 study in which they asked one hundred twenty men age twenty-one years and older to complete a fake IQ test and a real measure of self-consciousness. The researchers then gave the men fake feedback about their IQ test results, telling them that they had scored poorly on the test.

Afterward, the men were asked to participate in a wine-tasting experiment in which they could moderate the amount of wine they consumed. The researchers found that men who were highly self-conscious and received negative feedback on the fake IQ test drank larger quantities of wine than did men who were less self-conscious. These findings support the theory that highly self-conscious people’s alcohol consumption increases in response to a reduction in their self-esteem. It follows that celebrities, whose life experiences force them to be highly self-conscious, also may engage in heavy substance use after receiving negative feedback, such as poor reviews or seeing oneself featured in a tabloid.

Additionally, researchers Lynne Cooper, Michael Frone, and Marcia Russell conducted an online survey and found that both adolescents and adults reported using alcohol both to cope with negative emotions and to increase positive emotions. Additionally, psychological research studies have found that people report increased or inflated self-esteem after consuming alcohol. This research suggests that celebrities may abuse substances as a means to artificially increase their self-perception.

Celebrities also may be likely to abuse substances because of norms of substance use and abuse in celebrity culture. Anthropological research indicates that throughout the world, persons more often than not tend to conform to the accepted social practices and behaviors of their cultures; celebrities are no exception. Young or emerging celebrities may be socialized into a culture in which substance abuse is common, and these celebrities may then later take part in that cultural norm and encourage other celebrities to do the same.

Negative Social Effects

Several research studies have documented that people imitate behaviors they observe in others. In a famous study of observational learning, psychologist Albert Bandura and his colleagues Dorothea Ross and Sheila Ross showed children a film of an adult punching, kicking, beating, and insulting a doll. Children who had observed this aggressive behavior were significantly more likely to engage in aggressive play with the doll, imitating the behaviors of the adult and engaging in new aggressive behaviors.

Many other psychological studies have replicated these results, showing that people learn behaviors, both desirable and undesirable, through watching others. Observing celebrities engage in substance abuse increases the likelihood that members of the general public will imitate this behavior.

Other research in psychology suggests that celebrities are particularly influential role models because they have many of the factors that increase the likelihood of others selecting them as models for observational learning. These factors include attention, high social status, attractiveness, and in some cases, similarity in age, gender, or other characteristics. Additionally, celebrities who abuse substances often face less serious legal and financial consequences for their behavior than do noncelebrities. Therefore, those who are observing celebrity behaviors may be more likely to abuse substances themselves, as they do not see their role models experiencing significant negative consequences for their behavior.

Bibliography

Bandura, Albert, Dorothea Ross, and Sheila A. Ross. “Transmission of Aggression through Imitation of Aggressive Models.” Journal of Abnormal and Social Psychology 63.3 (1961): 575–82. Print.

Cooper, M. Lynne, et al. “Drinking to Regulate Positive and Negative Emotions: A Motivational Model of Alcohol Use.” Journal of Personality and Social Psychology 67.5 (1995): 990–1005. Print.

Duval, Thomas S., and Robert A. Wicklund. A Theory of Objective Self-Awareness. New York: Academic, 1972.

Hull, Jay G., and Richard D. Young. “Self-Consciousness, Self-Esteem, and Success-Failure as Determinants of Alcohol Consumption in Male Social Drinkers.” Journal of Personality and Social Psychology 44.6 (1983): 1097–109. Print.

Ingram, Rick E. “Self-Focused Attention in Clinical Disorders: Review and a Conceptual Model.” Psychological Bulletin 107.2 (1990): 156–76. Print.

Mor, Nilly, and Jennifer Winquist. “Self-Focused Attention and Negative Affect: A Meta-Analysis.” Psychological Bulletin 128.4 (2002): 638–62. Print.

Spradley, James, and David W. McCurdy, eds. Conformity and Conflict: Readings in Cultural Anthropology. 13th ed. Boston: Allyn & Bacon, 2008.

What different choice could Victor Frankenstein have made after the monster's request for a companion?

When the monster initially requests a companion, Victor agrees, feeling that he has some obligation to make this creature happy.  However, after Victor has some time to consider all the terrible damage this monstrous couple could do if they decided to be evil, he destroys the mate.  This compels the monster to vow that he will exact revenge on Victor by killing everyone he loves and rendering Victor as miserable as he feels himself to be.  Instead of resolving, in the end, not to give his creature a companion, Victor could have decided to do so.  His creature swears that he and his mate would leave the company of humankind forever and never injure anyone else, and it is possible that this is exactly what would have happened.  If Victor has created the female for him, it is possible, then, that Victor's best friend, wife, and father, at least, would have survived, and Victor's life would not have ended so early and tragically.

Who is the current “Deputy National Security Advisor” to President Obama? Explain why he has been the recent subject of criticism.

I wonder if the wording of this question might be somewhat imprecise.  The current Deputy National Security Advisor is a woman named Avril Haines.  Your question implies that the current holder of this office is a man.  In addition, Haines has not been particularly controversial.  For these reasons, I think your question may be intended to refer to a person holding another position.

I think your question is probably meant to refer to the current Deputy National Security Advisor for Strategic Communications.  This is a different office than the Deputy National Security Advisor.  This office is essentially a speech writing and public relations job.  The man who currently holds this office is named Ben Rhodes.

Rhodes has been the subject of controversy within the past few weeks.  On May 5, 2016, the New York Times Magazine ran a profile of Rhodes.  In that profile, he seemed to brag about misleading reporters (and, thereby, the American people) about the Obama administration’s negotiations with Iran over that country’s nuclear program.  The administration made a deal with Iran that many conservatives, in particular, felt was too weak.  They felt that the administration let Iran off too easily.  When Rhodes seemed to say that he had misled reporters and the public about the negotiations, critics of the deal seized on that as evidence that the administration was trying to trick people into accepting an agreement that was bad for the US and its allies.  It is for this reason that Ben Rhodes has been the recent subject of criticism.

How can I figure out the number of neutrons without knowing the mass number?

An atom contains protons, neutrons and electrons. Out of these particles, only protons and neutrons add to the mass of the atom, since electrons are relatively massless (they have very little mass as compared to protons and neutrons). We can determine the number of neutrons by knowing the mass number and atomic number (which is equal to the number of protons) of an element. 

Mass number = number of neutrons + number of protons 

= number of neutrons + atomic number

Thus, number of neutrons = mass number - atomic number

The atomic number of an element is available from the periodic table of elements. 

If the mass number is not given to us, we can still calculate the number of neutrons by determining the atomic mass of the element. This value is also available from the periodic table of elements. All the elements are listed in the periodic table with two numbers. The number on the top is the atomic number, while the number near the bottom is the atomic mass. 

The atomic mass is the weighted average mass of all the isotopes of an element. If we round off the atomic mass to the nearest whole number and subtract the atomic number from it, we get the number of neutrons.

That is, number of neutrons = atomic mass (rounded to nearest whole number) - atomic number.

For example, Carbon has an atomic number of 6 and an atomic mass of 12.0107. 

Thus, the number of neutrons in a carbon atom is:

12 (rounded off to nearest whole number) - 6 = 6.

Hope this helps.