What is the central metaphor of the poem "Harlem" by Langston Hughes?

In the poem "Harlem," Langston Hughes creates a central metaphor surrounding a dream by comparing a dream to multiple images of death and destruction in order to ask what happens to a "dream deferred," meaning a dream that has been delayed in being fulfilled.

He first compares a delayed dream to a "raisin in the sun," implying the dream is dried up and shriveled. Next, he asks if a delayed dream becomes infected "like a sore." Untreated cuts become infected and painful, leading to other major health problems, sometimes even death; therefore, in comparing a delayed dream to an infected wound, Hughes likens a delayed dream to something that causes severe pain and is destructive, even deadly. A third comparison is of a delayed dream to "rotten meat," which is meat that has gone uneaten for so long it is now dangerous for anyone to consume. By comparing a delayed dream to inedible meat, Hughes is wondering if dreams that go unfulfilled for a long time become so painful that they are noxious to the dreamer.

A fourth comparison is that of a delayed dream to sugar or syrup, which implies the dreamer starts seeing the dream as having been sugarcoated, meaning more appealing than it actually is. An example of seeing a dream as sugarcoated could be an African American wishing for an end to segregation but being led to believe that sharing the world with white people would lead to even more abuses and inequalities. By being led to believe such a fallacy, an African American may believe his or her present situation is better than the situation he or she dreams of, which would make him or her see the dream as sugarcoated.

Two final comparisons are that of a delayed dream to a load that is too heavy to bear and to something that explodes. Hughes's final comparison of a delayed dream to an explosion is the most powerful because it significantly contrasts with his other images of death and destruction. By comparing a delayed dream to an explosion, he implies that when dreams are prevented from being fulfilled, the dreamer builds up enough energy until the dreamer explodes in a burst of energy to fulfill the dream, just as we saw with the dawning of the Civil Rights Movement.

In A Dance of the Forests, what is Soyinka trying to help his audience understand through the parallels between characters, actions, and attitudes...

In my opinion, the concept that the author is trying to help the audience understand in A Dance of the Forests can be summed up in the words of Dead Woman:

The world is big but the dead are bigger. We’ve been dying since the beginning.

When you talk about the “parallels between characters” in A Dance of the Forests, you are speaking about a large amalgamation of living and dead as well as mortals and gods. What is important to understand is that Soyinka presents Yoruba culture for a Nigerian audience, so for an American reader, explanation is needed. As a short explanation, we should remember that Forest Head has disguised himself as a mortal human named Obaneji. He has invited four other mortals into the forest to welcome Dead Woman and Dead Man. The god Aroni has already taken the two under his wing due to their lack of acceptance by the living. The Forest Dance begins (and contains a kind of trial of the two living beings), but is interrupted by Eshuoro. The dance ends with the rebirth of Demoke through music and movement.

It is through Dead Woman’s observations that we learn the most about connections between the living and the dead. We learn that the past is extremely important in that it is “bigger” than the present. In fact, the past can directly affect what is happening now. The author, Soyinka, believes that the past is actually found within the people living in the present but that there is still a large divide between the two that causes tension and discord. The only way this divide can be traversed is through rituals such as the Forest Dance. These ceremonies, according to Soyinka, are vastly important for unification.

What is encoding?

Introduction

Most people find it easy to remember certain events from the past, such as the best vacation they ever had. They would remember their age and the most interesting things they saw or did at that time, even if the events occurred years before. If people could not remember events in their lives, they would have no personal history, skills, or talents. Fortunately, humans are able to take information from the world and store it in a mental representation that allows them to use that past information in a current situation. This ability is a function of the way the human memory
system works.

The memory system records events as they occur; this process is called encoding. The information is stored in a memory trace until it is needed. A memory trace remains in storage until a cue (a specific clue that triggers a memory) for that memory occurs, at which time the memory will be retrieved from long-term storage and outputted for use.

Short-Term and Long-Term Memory

In the model that is often used to illustrate memory systems, information comes into the memory system and is then transported to short-term memory (STM), where it is held for both further encoding into, and interaction with, long-term memory (LTM). There are different encoding strategies for information, depending on whether it is to be used by STM or LTM. Some encoding strategies are unintentional, but others can be used purposefully to increase memory abilities.

One of the characteristics of STM is that it can only store five to nine items, and these items remain in STM for only about eighteen seconds. Thus, information processed in STM must either be encoded into LTM or be lost from the system. If, for example, one needs the information of a telephone number, one probably will repeat the number until one can dial. This is known as a rehearsal strategy, and it serves to make the information available until one uses it.

One way of overcoming the capacity limitations of STM is by an encoding strategy called chunking: A group of items are chunked into meaningful units, which allows STM to hold more information and to be aided by LTM. For example, if one were asked to remember the letters FCTIIIBWAABM by rehearsing the letters, one would not easily remember the sequence. If, however, one were asked to remember the same letters arranged as FBI CIA TWA IBM, one would have no trouble recalling the sequence. The letters are chunked into four meaningful units that are small enough for STM and can be encoded into LTM because of their meaningfulness.

Another encoding strategy is the use of imagery. To remember a list of items, one makes a visual image of the items. For example, if one is to remember the pair of words dog and ribbon, one might make an image of the dog with a big red ribbon on its tail. Imagery is similar to another encoding strategy called elaboration. This, like imagery, adds details to an event and gives it more meaning so that it is more easily remembered. For example, given directions to a concert, one might start thinking about the time one walked down Main Street. By adding these details, one elaborates on the event and increases one’s memory. Elaboration is something that people do automatically, because memory is organized so that one event triggers memories of other events. If one hears the word dog, one automatically begins to retrieve things that one knows about dogs.

Another encoding strategy is called organization. This process groups items into larger categories of relatedness. For example, given a list of words to remember, such as dog, knife, rose, cat, horse, fork, daisy, spoon, and pansy, one would likely remember the words in three categories: flowers, utensils, and animals. This could be an intentional encoding strategy, and it aids memory because the retrieval (the process of getting information from the memory system) of the larger category also activates all the members of that category that are associated with it.

Associated Cues

The theory proposed by Endel Tulving called encoding specificity contradicts organizational encoding. Tulving proposes that any cue present and specifically encoded at the time of study will serve as an effective cue for retrieval, even over cues that would seem to be more likely to trigger the memory. For example, in 1971 Tulving and D. M. Thompson gave subjects a list of word pairs to remember. One group was given a list of word pairs that were strong associates of each other, such as hot-cold. The other list had words that were weakly associated with each other, such as blow-cold. Later, at a test session, the first word was given as a cue, and subjects were asked to fill in the second target word. Each group was given both strong and weak associated cues. It might seem likely that given the cue hot-_____, one would think of the target word cold even if one had been given the weakly associated pair of blow-cold at the time of study; however, this was not what happened. Subjects given the cue word blow at study could not recall cold when given hot as a cue but did very well when given their original cue word, blow. In other words, whatever cue word was encoded at the time of study was the best cue for retrieval of the target word at test regardless of how weakly or strongly associated the cue and target words were. Therefore, Tulving predicted that whatever cues are specifically encoded at the time of the event are the best cues for memory at the time of testing. Thus, encoding specificity can be extended to any context cues specific to the memory event. This includes the subject’s mood or surroundings.

Importance of Context

Sometimes the information that is encoded into the memory event is related to the context or surroundings of that event; instead of a word cue, the environment at the time of encoding can be a cue for retrieval. For example, in 1975, Duncan Godden and Alan Baddeley found that memory was better if subjects were asked to remember something in the same physical environment in which they previously had learned the material. They had subjects study a list of words on shore and a list of words underwater. If the list was learned underwater, memory was better if the recall test was also underwater rather than on shore, and vice versa. They concluded that the context provided additional cues for memory.

These context effects have also been demonstrated to include a person’s mood at the time of encoding, known as state-dependent effects. For example, in 1978 Gordon Bower hypnotized subjects into either a positive or negative emotional state and tested their memory for material when they were in the same and different emotional states. Students who were in congruent states of mind at study and test sessions had greater memory than students in different states of mind at study and test. Again, the contextual cues that were associated with a particular state of mind were present at both encoding and retrieval and served to aid recall by being specifically encoded with the event.

Thus, if one wants to increase one’s memory skills, the more types of encoding strategies one uses, the better one will be able to remember. In addition, it is important to remember that using the same cues for both study and test sessions will also result in better performance. Therefore, one might try to do some studying in the same room where one will be taking a test.

Evolution of Research

Cognitive psychology encompasses the study of all the functions of the human mind, including thinking, problem solving, reasoning, attention, consciousness, and processing information. It is considered a relatively new field of psychology, although its roots go back to the work of early psychologists in the late nineteenth and early twentieth centuries; in a sense they go back even further, to the philosophers of centuries past. In the late 1800s, both the renowned psychologist William James and Sigmund Freud, the founder of psychoanalysis, wrote about aspects of consciousness and attention. In the same time period, Hermann Ebbinghaus began studying verbal learning and memory, while Wilhelm Wundt attempted to research the structure of the mind with his method of introspection.

Another significant contribution to cognitive psychology began in 1904, when Ivan Petrovich Pavlov proposed his principles of conditioned learning. This led the way for further study into the learning processes of humans and animals; learning became considered to be an overt action, not a process of the mind. Thus, John B. Watson proposed in 1913 that behavior was the only suitable topic for psychology to study, and the processes of the mind became a taboo subject for many years.

It was not until World War II that cognitive psychology again became a legitimate topic for research. This occurred because the topic of human error became an important question for the military: pilots’ lives could be saved if more could be known about perception and actions. Researchers were employed to determine how decisions were made and to study the importance of attentional processes on performance. From this an entire field of study emerged, and the study of encoding strategies developed as a by-product of studying other processes of the memory system, such as attention, forgetting, and effective retrieval cues.

In the same time frame, the computer emerged; these areas of psychology were formulated in terms of an information-processing model of human memory. In other words, to understand the way memory systems work, a theoretical model of the brain was based on the computer. In 1968, Richard Atkinson and Richard Shiffrin suggested a model of memory that consisted of three memory stores, each with its own characteristics and functions. This consisted of the sensory register, the short-term memory, and the long-term memory. This information-processing model made the concepts of codes, storage capacity, trace duration, and retrieval failures an area of research. In studying these concepts, researchers discovered new topics of interest.

Research into encoding strategies is concerned with which elements of the environment are selected for encoding and how people can use this information to improve memory performance. The cue environment that is encoded is a topic of great interest, as it can aid performance if it can be predicted. Such components of the cue environment as gestures and emotions that are all encoded below the level of awareness are only beginning to be studied, and they should lead to a much better understanding of how to improve memory.

Bibliography

Anderson, J. R. Cognitive Psychology and Its Implications. 6th ed. New York: Worth, 2005. Print.

Dehn, Milton J. Working Memory and Academic Learning: Assessment and Intervention. New York: Wiley, 2008. Print.

Ellis, Henry C., and Reed R. Hunt. Fundamentals of Human Memory and Cognition. 4th ed. Dubuque: Brown, 1989. Print.

Eysenck, Michael W., and Mark T. Keane. Cognitive Psychology. 6th ed. New York: Psychology, 2013. Print.

Greene, Robert L. Human Memory: Paradigms and Paradoxes. New York: Psychology, 2014. Print.

Groome, David, et al. An Introduction to Cognitive Psychology: Processes and Disorders. 2nd ed. New York: Psychology, 2013. Digital file.

Schwartz, Barry, and Dan Reisberg. Learning and Memory. New York: Norton, 1991. Print.

Smith, Frank. Comprehension and Learning: A Conceptual Framework for Teachers. New York: Holt, 1975. Print.

Tulving, Endel. Elements of Episodic Memory. London: Oxford UP, 2008. Print.

What is genomic medicine?

Genetics

Most diseases have a genetic component, making them a target for genomic medicine. Some genetic variations are known to cause disease and are referred to as Mendelian disorders. Examples include cystic fibrosis
(CF) and Huntington’s disease. Overall, single-gene disorders are rare. For example, CF, the most common genetic condition in Caucasians, affects only 1 in 2,500 to 3,500 infants.

Genomic medicine will have the greatest impact on health in the United States via common complex disorders, which are caused by a combination of one or more environmental and genetic factors. Instead of “causing” the disease, genetic variations contribute to disease susceptibility. Examples include heart disease, Alzheimer’s disease, and autism.

Infectious diseases are least impacted by genetic factors because the organism causes the disease. How the body reacts to the organism, however, may have a genetic component. Tuberculosis
is known to cause symptoms in only a small percentage of people who become infected. The variability in expression of this disease in exposed individuals is believed to be genetic and is a current topic under investigation.

Prediction

The most immediate application of genomic medicine is disease prediction. Family history is currently the most useful genetic information for disease prediction. Genetics is likely to contribute more to a disease in families where it appears at an earlier age than typical, with more severity, and/or in more individuals. A person’s risk is estimated based on these factors and how closely related affected relatives are. For example, in a family where individuals develop heart disease at a young age despite a healthy diet and lifestyle, genetics is likely to have a higher impact than in one where one individual develops it in old age after a lifetime of unhealthy choices.

Once a gene is clearly established to cause or contribute to disease, it offers another tool to predict risk. This is common for Mendelian but not complex disorders because most genes are not known. Even when available, tests may not be offered immediately as a result of poor clinical validity and/or utility. An example is genetic testing for a variant of the Apoliprotein E gene that confers a risk for Alzheimer’s disease. Testing is typically not recommended because the clinical validity is low and there is no proven clinical utility. In other words, many people who test positive will not develop the disease and there is no proven strategy to prevent or delay it. However, research is quickly closing the therapeutic gap of this and many disorders, opening the doorway for risk management options, some of which are already available.

Risk Management: Screening and Prevention

The greatest promise of genomic medicine is to use risk information to identify disease early, delay disease, or, most important, prevent disease. For example, scientists can identify individuals at genetic risk for several types of cancer, including breast and colon cancer. For these individuals, screening begins earlier and is more aggressive. For those at risk for hereditary breast and ovarian cancer syndrome, a drug called Tamoxifen
has been shown to reduce the risk of breast cancer. In addition, prophylactic removal of ovaries and/or breasts has also been shown to reduce drastically the risk of cancer to these organs. While extreme, these strategies can save lives. Fortunately, research in other risk management strategies continues for these diseases and others.

Diagnosis

Genetic information can improve diagnosis in many ways and is commonly used for Mendelian disorders. For some disorders, a clinical diagnosis can be uncertain or elusive. Testing the patient for genes known to cause or contribute to the disease can aid the clinician greatly, especially when a clear diagnosis facilitates treatment. Genetic information may not always be in the form of genotype information. Expression analysis can also be useful to make a diagnosis. For example, oncologists can use expression analysis to establish a more precise diagnosis in leukemia patients. This is useful for determining prognosis and treatment. For many disorders, different genetic variations may cause or contribute to the same disorder. For example, autism in one family may be caused by different genetic factors than in another. Knowing the genetic contribution may help others in the same family obtain an earlier diagnosis, or in the future, these genetic differences may be shown to benefit from different therapies.

Treatment

One of the most touted treatment benefits of genomic medicine is pharmacogenetics, using genetic information to improve prescribing. Presently in the United States, adverse drug reactions (ADRs) are a huge health burden. The Food and Drug Administration (FDA) admits that approximately 100,000 deaths annually are attributable to ADRs; furthermore ADRs are estimated to cost more than $100 billion a year. In addition, the efficacy of a drug varies greatly among patients. Without advance insight, doctors often rely on trial and error to find the best drug for the patient. Genetic variation is believed to play a large role in both ADRs and efficacy. The FDA unanimously agreed that a certain gene variant predicts the efficacy of Tamoxifen, a drug prescribed in some women to reduce the risk of breast cancer recurrence. Having a certain variant may reduce the drug’s effectiveness and even increase the chance of a cancer recurrence. This is just one example of many to come where genetic information improves prescription practices.

Another treatment possibility is tailoring drug development to disease biology. Identifying and learning about the genes that cause or contribute to a disorder has and will continue to provide new therapeutic targets through greater understanding about the biology of the disorder. For example, enzyme replacement therapies are available for some Mendelian disorders in which the gene codes for a defective enzyme. A future application on the other end of the spectrum is a genetic variation that confers protection from the human immunodeficiency virus (HIV) in a small percentage of the population. This variant may offer solutions for new treatment strategies.

Impact

Genomic medicine will come to define the next era in medicine. Instead of a one-size-fits-all approach that prioritizes treatment over prevention, medicine will evolve to capitalize on genetic information to tailor care to the individual that prioritizes prediction and prevention of disease. Not only will this result in improved health care, but it should result in significant cost savings as well. Before this scenario can occur, however, numerous barriers must be overcome, including reimbursement struggles and educating health care providers, among others.

Key terms



adverse drug reaction

:

undesirable side effect to a medication




clinical utility

:

ability to use results to improve patient care




clinical validity

:

the likelihood a person who tests positive will develop a disorder




expression analysis

:

examining RNA to determine which genes are being transcribed




therapeutic gap

:

a situation in which there is no mechanism to improve a health outcome for those identified at risk





Bibliography

Guttmacher, Alan E., and Francis S. Collins. “Genomic Medicine: A Primer.” The New England Journal of Medicine 347 (2000): 1512–20. Print.

Innovations in Service Delivery in the Age of Genomics: Workshop Summary. Washington, DC: National Academies, 2009. Print.

Khoury, Muin J., Wylie Burke, and Elizabeth J. Thomson. Genetics and Public Health in the Twenty-First Century: Using Genetic Information to Improve Health and Prevent Disease. New York: Oxford UP, 2000. Print.

Kumar, Dhavendra, and Charis Eng. Genomic Medicine: Principles and Practice. New York: Oxford UP, 2014. Print.

McCarthy, J. J., H. L. McLeod, and G. S. Ginsburg. "Genomic Medicine: A Decade of Successes, Challenges, and Opportunities." Science Translational Medicine 5.189 (2013). Print.

Pfeffer, Ulrich. Cancer Genomics: Molecular Classification, Prognosis, and Response Prediction. New York: Springer, 2013. Print.

Simon, Richard M. Genomic Clinical Trials and Predictive Medicine. Cambridge: Cambridge UP, 2013. Print.

Suther, S., and P. Goodson. “Barriers to the Provision of Genetic Services by Primary Care Physicians: A Systematic Review of the Literature.” Genetics in Medicine 5 (2003): 70–76. Print.

What is the relationship between genetics and substance abuse?

Genetic Evidence

The response of the human body to specific chemicals has long been known to have a genetic basis. In general, these effects can be considered to fall within two themes: in the presence of receptors on the cell surface that can be activated following the binding of a chemical and in the regulation of a metabolic pathway through the mechanism of chemical activation of specific enzymes. This is particularly true when applied to brain chemistry.

The functions of specific regions within the brain, including those that could include pleasure centers or those that control other forms of reactions to specific drugs, are subject to hereditary control. The expression of cell receptors and the production of enzymes that control pathways in the brain, each regulating the ability to respond to drugs, have an underlying genetic control.

Historically, the treatment of substance abuse, including that involving alcohol and drug addictions (both legal and illegal) has centered primarily on the moral or behavioral aspects of the problem. Treatment once believed that the addicted person has made a choice, first to use the substance and then to continue its use until addiction removes any personal control. While there is certainly a behavioral component involved—the initial use of the substance is affected by voluntary action and environmental factors—increasing evidence suggests a genetic predisposition to the addiction that may follow.

Most historical studies that have attempted to establish a genetic basis for addiction have utilized twin studies. These studies involve a comparison between twins, ideally living separate lives so as to avoid environmental influences in the study, in which the prevalence of substance abuse and addiction may be compared. Numerous epidemiological studies of twins have shown a significantly increased level of risk, even in the absence of environmental influences: If one twin developed an addiction, the other also demonstrated a significantly higher level of risk of doing so.

Adoption studies have reinforced the conclusions reached through twin studies. If a birth parent exhibited problems in the use of alcohol, then the child demonstrated significantly increased risk in exhibiting the same behaviors. However, if the child was adopted and thus did not share genetic features with the adoptive parent, the child exhibited no increased risk. Similar results also were found in cases of drug addiction.

The development of biochemical methods for studying brain chemistry and regulation of pleasure pathways has provided a means to investigate addiction at the molecular level. Studies have shown that some forms of addiction may be exacerbated by the expression of specific genes or pathways in the brain, which are controlled by the drugs in question. Another challenge in attempting to sort out what genes might be involved in addiction is that, often, no single gene is always involved. Rather, the interaction of a variety of genes, and in some cases metabolic pathways in the brain, contributes to addiction.

Genetics of Alcohol Addiction

Though the evidence is largely anecdotal, there is some indication that alcoholism may at some level be subject to genetic factors. It is known that alcoholism frequently repeats through family generations. As noted, studies of twins and comparisons between adoptive or biological children, in which a parent exhibits alcohol problems, support the argument for a genetic component to alcohol addiction. It remains unclear if alcoholism is primarily genetic or whether tendencies to addiction reflect the environment in which the person is raised. Experts agree that alcoholism may result from a combination of factors.

Supporting the argument that genetics may play a role in alcoholism was the discovery of a genetic link between a specific gene that encodes alcohol addiction and a molecule called the cyclic AMP responsive element binding protein (CREB). The CREB gene plays a role in the regulation of brain function during development; in particular, it has an association with the portion of the brain known as the amygdala. The scientific evidence for the role of the CREB gene supports what is known about the function of the amygdala, the region in the central brain that determines a portion of the body’s response to emotional disorders and stress.

Persons subject to alcoholism frequently have abnormal reactions to stress, a problem that may be ameliorated by alcohol. Depression and other abnormal responses to stress seem to reflect abnormalities in signaling patterns and gene expression within the amygdala. These abnormalities in turn seem to be caused by improper CREB protein regulation. Alcohol appears to reverse this process. In the presence of increased levels of alcohol, the CREB protein becomes functional, activates the signals within the amygdala, and alleviates the effects of stress. Reduced levels of the CREB protein in the amygdala exacerbates the anxiety levels of the subject, which then increases the subject’s desire (and need) for alcohol.

While most of these studies have been carried out in nonhuman animals, many of the identical physiological changes that occur in the brains of test animals, such as rats and mice, have identical counterparts in the human brain and its response to alcohol. Among the questions that should be addressed is whether the need for alcohol forms the basis for its addiction or whether the long-term abuse of alcohol results in the changes found within the brain.

Genetics and Stimulants

Stimulants such as cocaine, amphetamines (for example, methylene-dioxymethamphetamine, or ecstasy), and even tobacco and caffeine, seem to have in common the ability to utilize common mechanisms within the brain. One mechanism in particular on which addiction studies have focused is the regulation of certain neurotransmitters, chemicals released by neurons in the brain that act to stimulate nerve endings on adjacent nerve cells.

Neurotransmitters such as dopamine
, long known for its association with Parkinson’s disease, control neural pathways in the portion of the brain known as the striatum, the portion of the forebrain that controls emotions such as pleasure and certain behaviors. Stimulants such as cocaine or amphetamines increase the level of dopamine—cocaine by inhibiting the reuptake of dopamine and amphetamines by increasing their release. Regardless of their mechanism, stimulants cause drug-induced highs.

Studies in mice that have attempted to identify those genes that are particularly sensitive to the presence of stimulants have identified one gene that seems to play a common role: the post-synaptic density-95 (PSD-95) gene. The product of PSD-95 appears to function in regulating the structure of the receptor that serves as the target for dopamine in the pleasure centers of the striatum. Reduced levels of the PSD-95 protein in mice led to an increased response following exposure to cocaine. The sensitivity of mice to cocaine appears to correlate with the level of the PSD-95 protein.

Because most stimulants, including tobacco and alcohol, likewise act in part by increasing the level of dopamine within the striatum, the PSD-95 protein may represent a common feature in the response to the presence of these drugs. Genetic variation in the activity of the PSD-95 gene may be one of the determining factors in both the behavioral response in using stimulants and in the likelihood the user may ultimately become addicted.

Bibliography

"Family History and Genetics." National Council on Alcoholism and Drug Dependence. NCADD, 25 Apr. 2015. Web. 29 Oct. 2015.

Kendler, Kenneth, and Carol Prescott. Genes, Environment, and Psychopathology: Understanding the Causes of Psychiatric and Substance Use Disorders. New York: Guilford, 2007. Print.

Kipper, David, and Steven Whitney. The Addiction Solution: Unraveling the Mysteries of Addiction through Cutting-Edge Brain Science. New York: Rodale, 2010. Print.

Miller, William, and Kathleen Carroll. Rethinking Substance Abuse. New York: Guilford, 2006. Print.

Wand, Gary. “The Anxious Amygdala: CREB Signaling and Predisposition to Anxiety and Alcoholism.” Journal of Clinical Investigation 115 (2005): 2697–99. Print.

What is respiration?

The Mechanics of Respiration

The primary function of respiration is performed by the
lungs and their associated tissues. Air must be breathed in through the mouth and nose through the larynx (voice box) into the main airway, the
trachea (windpipe). Inside the chest, the trachea branches into the two main airways called bronchi, which in turn successively branch many times into small bronchi called bronchioles. These airways end in very small sacs called alveoli. These alveoli have a very thin membrane separating the air space from the blood in the capillaries. Oxygen (O2) diffuses through the alveolar membrane across the capillary membrane and into the blood to be taken to all the tissues of the body. Tissues excrete carbon
dioxide (CO2) into the blood that is carried back to the lungs. Carbon dioxide diffuses from the blood into the alveoli and is carried back through the airways and out of the lungs with the exhaled air. The mouth and nose humidify dry air to ensure that the linings of the lower airways do not dry out. The main airway divides to supply the left and right lungs. These large airways are cylindrical. Their circular shape is maintained by C-shaped cartilage in the walls. The stiff walls prevent collapse of the airways and the loss of gases through the walls of these “conducting” airways. The airways branch repeatedly into smaller airways. As the airways become smaller, they have less cartilage, until, in the very smallest airways, the cartilage is absent. These thin airways, which are called respiratory bronchioles, have alveoli budding from their walls. Gases may diffuse through the walls of these airways. These bronchioles become alveolar ducts and then erupt into lobular sacs of alveoli. There are about 300 million alveoli in an individual’s lungs, which provide about 70 square meters of extremely thin membrane through which most gas exchange occurs.

The lungs are elastic in nature and have a tendency to collapse. They do not because they adhere to the inside surface of the chest wall in much the same way that a moist suction cup adheres to a smooth surface. The two surfaces may slide against each other without separating. The chest wall has a tendency to expand because the rib cage and the muscles between the ribs (the intercostal muscles) tend to pull the chest out and up. The balance of these forces (elastic recoil and chest wall expansion) keeps the lungs slightly expanded at all times. Like balloons, the alveolar sacs have a tendency to collapse. The lungs produce a substance called surfactant that keeps the small air sacs from collapsing.

Air gets into and out of the lungs in the following way. The lungs expand, drawing air into them. The lungs adhere to the diaphragm in the same way that they adhere to the chest wall. When the muscles of the diaphragm contract, the lungs are pulled down. At the same time, the intercostal muscles contract slightly, making the chest wall rise up and out. These actions cause the lungs to expand. This expansion causes the pressure inside the lungs to decrease, sucking in air. When the intercostal muscles and diaphragm relax, the elasticity of the lungs causes them to deflate again to their resting state. This passive recoil of the lungs causes the pressure inside them to increase and pushes air out of the lungs.

The amount of air breathed in each breath is called the tidal volume. Each breath contains about 500 milliliters of air. Normally, a human being breathes in and out about twelve times in one minute. This results in about 6,000 milliliters of air being breathed each minute. Not all air that enters the mouth or nose reaches the area of the lung where gases are exchanged. About 150 milliliters of each breath stay in the larger airways. Therefore, 4,200 milliliters of air reach the alveolar space each minute. Since the chest wall and the chemical surfactant tend to keep the lungs partially inflated even after the breath is normally exhaled, additional air can be blown from the lungs, if one exhales consciously and forcefully. The volume of air blown out in this manner, which is called the expiratory reserve volume, is normally about 1,000 milliliters. Additional air can also be drawn into the lungs after a normal inspiration. This volume, the inspiratory reserve volume, is normally about 3,000 milliliters. The sum of the tidal, inspiratory reserve, and expiratory reserve volumes, which is called the vital capacity of the lungs, is about 4,500 milliliters. If these reserves are called into play, tidal volume can be increased almost tenfold. The breathing rate can also be increased at least twofold. Therefore, total alveolar ventilation can be as
great as 120,000 milliliters per minute.

The oxygen that is drawn into the lungs diffuses into the blood, and carbon dioxide diffuses out of the blood into the alveolar spaces to be exhaled. Fresh air exerts a pressure (barometric pressure) of 760 millimeters of mercury (mmHg). Oxygen is 21 percent of air; therefore, it has a partial pressure of about 160 mmHg. It mixes with air in the lungs that has lost oxygen to the blood. This results in a reduction in the partial pressure to about 100 mmHg by the time the breathed air reaches the alveoli. Blood pumped by the right ventricle of the heart into the lungs to be oxygenated has only 40 mmHg of oxygen. Oxygen diffuses from an area of high concentration in the alveoli to the blood, which has a low concentration. This
diffusion process is rapid enough that the partial pressure in the blood becomes equal to that of the alveoli before it courses one-half the distance through the lung capillary. Although the partial pressure is 100 mmHg, the amount of oxygen carried in blood fluids (plasma) is low. Therefore, without red blood
cells containing hemoglobin, blood cannot carry much oxygen to the tissues.

Hemoglobin is a very efficient carrier of oxygen. Each molecule of hemoglobin can carry four molecules of oxygen. In the same way that a disposable diaper absorbs water, hemoglobin absorbs oxygen from the plasma, allowing more oxygen to diffuse into the blood from the alveoli. As hemoglobin absorbs oxygen, it turns from a bluish purple to red. Between partial pressures of 20 and 100 mmHg, hemoglobin can absorb a large amount of oxygen. Hemoglobin does have a maximum capacity for oxygen that is reached at about 100 mmHg. Hemoglobin is called saturated at this point, and it can hold no more even if the partial pressure of oxygen increases. Hemoglobin is filled to half capacity by the time the plasma partial pressure reaches 30 mmHg. When the partial pressure increases from 20 to 100 mmHg, the increase in the amount carried by the plasma is 2.1 milliliters of oxygen per liter of blood. With the same change in partial pressure, hemoglobin increases the amount of oxygen carried by approximately 150 milliliters per liter of blood. Blood can carry more
than seventy times the amount that plasma alone can carry at this range of partial pressure. If the partial pressure does increase beyond 100 mmHg, little more oxygen is added to the blood. Oxygen is added to plasma in the dissolved form at a rate of 0.03 milliliters of oxygen per liter of plasma for each 1 mmHg change in the partial pressure.

Oxygen is carried to the tissues by the blood, where it is efficiently removed from hemoglobin. The partial pressure in the tissues is between 20 and 60 mmHg, depending upon the particular tissue and the rate at which the tissue uses oxygen. Inside the tissues, the partial pressure can be as low as 1 mmHg, providing a large difference to stimulate diffusion into the tissues. Oxygen is quickly absorbed by the tissue. Just as rapidly, carbon dioxide diffuses out of the cells and into the blood. There are also special ways in which the blood carries carbon dioxide to increase its capacity.

Carbon dioxide dissolves in plasma in much the same way that oxygen does, but supplemental mechanisms are required to carry the large amounts of carbon dioxide produced by the body. Carbon dioxide is also absorbed by red blood cells. It diffuses into the red blood cells, where it is changed in chemical form. Stimulated by an enzyme, carbonic anhydrase, carbon dioxide is combined with water and converted to a new chemical (the bicarbonate ion). The bicarbonate ion can attach to hemoglobin in this form. This, in effect, keeps the concentration of carbon dioxide in the plasma low, allowing more to diffuse. In the normal range of operation (40 to 50 mmHg), blood can absorb about 470 milliliters of carbon dioxide per liter of blood. With this large capacity, the partial pressure need change only a few mmHg to carry all the carbon dioxide that is produced by the tissues.

The anatomy of the lungs and the functioning of the respiratory system are well suited to meet most of the challenges that life presents. Exercise is a good example of how the respiratory system can handle a challenge. At rest, a fit young man breathes 6,000 milliliters of air per minute and uses about 250 milliliters of oxygen per minute to supply his body’s needs. When exercising to his maximal capacity, the same individual may use as many as 4,000 milliliters of oxygen per minute. To supply this increased demand, the respiratory system must utilize all the reserve volumes discussed above and increase the breathing rate to a total of 120,000 milliliters of air per minute. The brain senses the movement of the arms and the legs. It also senses the greatly increased amount of carbon dioxide produced by the exercising muscles. In turn, the brain sends signals to the chest and diaphragm to breathe much deeper and faster.

Another example of the large reserve capacity of the human lungs is the ability to hold the breath. Since only a small amount of oxygen from each breath is used, a person can take a deep breath and hold it easily for nearly one minute. Some pearl divers can take a deep breath and swim underwater for four minutes or longer. The urge to breathe that one experiences while holding one’s breath is produced when the brain senses the buildup of carbon dioxide and the decrease of oxygen in the blood.

The brain also uses its ability to sense the oxygen in the blood to adjust to unusual environments. At high altitudes, there is less oxygen in the air. With less oxygen in the air, less gets into the blood. The brain senses this condition and signals the respiratory system to breathe more air. Therefore, when one travels into the mountains, one will breathe slightly deeper and faster. One is not aware of the increased breathing until fairly high altitudes are reached (above 10,000 feet). If one begins to exercise, however, performing even mild exercise such as brisk walking, one will be very aware of breathing heavily. This situation is greatly intensified if the person has diseased lungs. With some severe lung diseases, even people living at low altitudes (sea level) have shortness of breath, and some need to breathe air supplemented with extra oxygen.

Disorders and Diseases

The major type of lung disease, which is called obstructive disease, has three subclasses. The first is general obstruction, a disease in which material is abnormally present in an airway. The second is disease in which the large airways are narrowed. The third is disease in which the small airways and alveoli are diseased.

The case of general airway obstruction is simple. The simplest form is one in which a foreign body such as food or part of a child’s toy is lodged in a large airway, such as the trachea or a main bronchus. The Heimlich maneuver (standing behind the affected individual, clasping the hands in a fist just below the rib cage, and thrusting up and in with the fist) is very effective in dislodging food caught in the trachea or larynx. An object that is small enough (such as a peanut), however, can get farther into the lung, in which case special instruments or surgery are necessary to remove the object. Tumors can also grow into the opening of an airway and obstruct it. Severe cases of tonsillitis are examples of this type of obstruction. Surgery is sometimes necessary to remove such a tumor if it limits airflow.

Large-airway narrowing is another type of related airway obstructive disease. Asthma and bronchitis are examples of this type of disease. The walls of the trachea and larger bronchi become thickened and thus make the passageway for air smaller. In addition, the specialized muscle (smooth muscle) surrounding the large airways has a tendency to contract, making the opening in the airway even smaller. These conditions result in difficulty of breathing, particularly when inhaling. Relatively rapid airway narrowing caused by smooth muscle contraction is called an
asthma attack. Irritants such as air pollution, tobacco smoke, and pollen can start an asthma attack. Exercise, particularly in cold weather, can also stimulate an attack in some asthmatics. Asthma attacks can last for hours and sometimes days. There are some drugs, frequently taken in an inhaled form, that help relieve the symptoms by relaxing the smooth muscle. Many cases of asthma, however, are resistant to these drugs. Some asthmatics have benefited from drugs that help decrease the frequency and severity of
attacks. Asthma usually begins in childhood and has a tendency to run in families.

Chronic obstructive pulmonary disease is the term that characterizes obstructive disease of the smallest airways and alveoli. Emphysema and chronic bronchitis belong to this class of lung disease. Emphysema consists of enlargement of the smallest bronchioles and the alveolar sacs. The walls of the alveoli disappear, and with them the capillaries. Therefore, the area previously used to exchange oxygen and carbon dioxide is lost. Since the air sacs are enlarged, the oxygen must travel farther to diffuse into the blood. Emphysema can be indicated by chest X rays and pulmonary function tests but cannot be definitely identified until after death. Emphysema is frequently associated with chronic bronchitis. Chronic bronchitis is characterized by enlargement of the mucous glands and by excessive mucus (sputum) production in the bronchial tree. The enlargement of the mucous glands alone can increase the resistance to airflow. Bronchitis is considered chronic when mucus is produced for three months of the year for at least two years.
The sputum can be very thick and may form into plugs to completely block off areas of the lung from airflow. Chronic obstructive pulmonary disease is generally a combination of both emphysema and chronic bronchitis of varying degrees. Persistent cough with expectoration is a normal symptom of this lung disease. With the destruction of airways and alveoli, some of the elastic recoil of the lungs is lost. As a result, exhalation is very laborious. Excess air is left in the lungs at the end of the exhalation, causing the chests of sufferers to be enlarged. Chronic obstructive disease is commonly found in long-term smokers.

Restrictive lung disease is another major classification of lung diseases. The main general feature of this class is primary changes in respiratory system tissues that restrict the movement of the lungs and thus respiration. Cystic fibrosis is the primary example of this disease. Cystic fibrosis appears to be caused by a malfunction of the immune system that produces a thick scarlike substance in the walls of the alveoli. The walls of the alveoli become thick and very stiff (fibrous). In some cases, the scar tissue grows across the small airway opening and closes off the airway. These closed air pockets are called cysts. The stiffness of the airways increases the elastic recoil of the lungs, making it very difficult to inhale.

Perspective and Prospects

Hippocrates (c. 460-c. 370 b.c.e.) recognized the breathing of air as an important function. He believed, however, that the function of breathing was to cool the generator of heat, the heart. Aristotle (384-322 b.c.e.) believed that air was breathed into the arteries, which carried it in the gaseous form to the rest of the body. Galen (129-c. 199 c.e.) transformed medicine from a hypothetical (philosophical) science into an experimental science by performing the first experiments on animals. He found that the arteries did not contain air, and he deduced that a quality of air (oxygen had not yet been discovered), not air itself, was important to life. In the seventeenth century, William Harvey discovered that blood circulated from arteries to veins in both the lung and the rest of the body, and oxygen was identified at the end of the eighteenth century by Joseph Priestly. Claude Bernard described the union of oxygen and hemoglobin at the end of the nineteenth century.

Many major technological advances have been made. Machines have been developed to assist and in some cases completely take over the function of respiration. Respirators can assist patients who have difficulty breathing on their own. Victims of poliomyelitis whose muscles for respiration are no longer functional, as well as paralyzed patients, have been greatly helped by respirators. Respirators maintain breathing during surgery when the patient receives general anesthesia. They also assist premature babies whose lungs are not fully developed. Scientists can now make the chemical surfactant that helps keep the lungs open. Premature babies frequently do not make enough surfactant; therefore, administration of synthetic surfactant can be lifesaving. Some machines can completely assume the function of the lung. These machines, called extracorporeal membrane oxygenators, can do the job of both the heart and the lungs. They are used in heart transplantation operations. They are also used to function in the place
of severely damaged lungs of newborns until those lungs can repair themselves.

Knowledge of the functioning of the respiratory system has allowed humans to function in unusual environments. Humans are able to travel to high altitudes (for example, the top of Mount Everest) with the assistance of supplemental oxygen. Travel into outer space, where there is no oxygen, is now possible because an atmosphere can be created that is suitable for long-term living in space. Experimental work is being performed with the breathing of special liquids instead of air. Success with liquid breathing may allow humans to exist in different environments, such as the deep sea, and may also have therapeutic value.

Bibliography

Kittredge, Mary. The Respiratory System. Edited by Dale C. Garell. Philadelphia: Chelsea House, 2000.

Levitzky, Michael G. Pulmonary Physiology. 7th ed. New York: McGraw-Hill Medical, 2007.

Mason, Robert J., et al., eds. Murray and Nadel’s Textbook of Respiratory Medicine. 5th ed. Philadelphia: Saunders/Elsevier, 2010.

McLafferty, Ella. Carolyn Johnston. Charles Hendry. Alistair Farley. "Respiratory System Part 1: Pulmonary Ventilation." Nursing Standard. 27.22 (2013): 40–47. Print.

Parker, Steve. The Lungs and Breathing. Rev. ed. New York: Franklin Watts, 1991.

"Respiratory System Overview." MedlinePlus. August 2, 2011.

"The Respiratory System." National Heart, Lung, and Blood Institute. July 17, 2012.

Ware, Lorraine B., and Michael A. Matthay. “The Acute Respiratory Distress Syndrome.” New England Journal of Medicine 342, no. 18 (May 4, 2000): 1334-1349.

"What Are the Signs and Symptoms of Cystic Fibrosis?" National Heart, Lung, and Blood Institute. June 1, 2011.

West, John B. Pulmonary Pathophysiology: The Essentials. 7th ed. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins, 2008.

Who is a better basketball player, Stephen Curry or Kyrie Irving? Who has a better shoe line?

In the NBA, a player’s success is measured by many characteristics. The main characteristic is winning championships. Kyrie Irving has won no championships while Stephen Curry has won one championship. In pro sports, it is all about winning championships.

There are a few other things to consider. Stephen Curry was the MVP last year in the NBA. Kyrie Irving has no MVP awards. Stephen Curry is playing on a team that has a chance to win the most regular season games ever. Kyrie Irving plays on a team with the best player in the league, LeBron James. That team has never won more than 70 regular season games. Stephen Curry is the best player on his team. Finally, Kyrie Irving has been injured during his career in the NBA. Kyrie Irving has played in less than 60 games in three of his five seasons in the NBA. Stephen Curry has been relatively free from injury. Stephen Curry has played in at least 74 games each season except for one season. Based on these factors, Stephen Curry is the better player.

Regarding the shoes, I will leave that up to you. Shoes are a matter of personal preference.

How did World War I change the world? How did it usher in a new age for diverse societies between 1910–1939?

World War I contributed to major changes in world societies, economies and other aspects of life. The conflict was greater than any previous war in history at the time, involving 28 countries with the highest war mobilization recorded.

The war led to the redrawing of territorial boundaries; old countries fell with new ones taking their place. Monarchies fell, and electoral democracies were established to replace them, leading to direct and indirect political changes in different countries. World War I ushered in the idea of universal suffrage, bringing radical changes in global politics.

The communist revolutionary wave was also attributed to World War I. The continued spread of communism in many European countries changed global relations and led to future conflicts with anti-communist regimes.

World War II and the Holocaust happened as a result of World War I. Germans were generally dissatisfied with the Treaty of Versailles, which forced them to assume complete responsibility for the war and make reparations. This, in turn, created a favorable environment for the rise of Hitler and the Nazi party, who took advantage of the negative sentiments expressed by the community.

The war resulted in the shift of financial bases from Europe to the United States. World War I plunged the participating countries into debt, especially Britain, which was a financial power previously.

World War I also ushered a period of technological advancement. Although this was initially directed at war efforts such as the development of the Atomic bomb and tanks, similar techniques (advanced mass production techniques) were later used in medicine and other progressive ventures.

Socially, the war prepared grounds for the establishment of Israel, Iraq, Syria and Lebanon in the Middle East. Poland, Czechoslovakia and Yugoslavia were also established or re-established in Europe. Diverse societies were offered an opportunity to politically and socially assert themselves in the global sphere. Yugoslavia emerged as a multi-national state. Czechoslovakia was divided among two Slavic nationalities. Albanians merged with Greeks and Serbs while the Turkish people merged with the Bulgari in Bulgaria.

Where does Brian find shelter? Why does he consider the find lucky?

As Brian is trying to figure out his situation, he decides that he ought to check around the lake to see what he can see and on the far side he finds a spot that will be particularly useful as a shelter. He believes it is lucky that he ever decided to search in the first place and that it led him to this very useful rock formation.

He describes the place as looking like part of the rock had been "scooped by something" to make a perfect smooth overhang that is just about tall enough for him to stand in. It is lucky because he will only have to wall off a small part of it to give him protection from the worst of the elements. He felt fortunate to find someplace that would be waterproof and work better than anything he knew how to construct on his own.

After Major’s death, what happens to the idea of rebelling against Man in Animal Farm by George Orwell?

At the beginning of Chapter Two of Animal Farm, Old Major dies in his sleep. This event galvanizes the animals into action, as we learn from the text:

Major’s speech had given to the more intelligent animals on the farm a completely new outlook on life.

While the animals have no idea when the rebellion against Man will occur, they are certain they must prepare for it. They begin to organize themselves; the pigs, "generally recognized as the cleverest," became the leaders. They take the text of Old Major's speech and turn it into a "complete system of thought" called Animalism. The pigs teach these principles to the other animals at secret meetings they hold in the barn on several nights of the week. They also sing the song "Beasts of England," which Old Major taught them before he died. 

It is now just a matter of time before the Rebellion takes place and the animals successfully overthrow Mr. Jones and take control of Animal Farm.

"It is a good idea, when drafting an essay, to establish a 'working thesis'." Is this true?

True.  A “working thesis” is different from a “thesis statement” in that the phrase implies some doubt or tentativeness on the part of the essayist, some room for persuasion. Far from finding support for an already solidified view on the debated subject, the essayist with a working thesis is looking into research on the topic, in order to establish not only a point of view but also support for that point of view (along with arguments against any opposing view). The refined essay product will state in its thesis statement the point of view to which the “work” of the researcher has led him/her.   It is a much more sophisticated way to approach a controversial topic than to begin arguing a point of view that had been adopted via less logical means (personal experiences, emotional responses, automatically attractive views, common social views, etc.) and invariably leads to a more convincingly constructed essay.

What are some metaphors in Acts 4 and 5 of Julius Caesar?

A metaphor is a type of figurative language where something is described as being something other than it is.  It is an indirect comparison. Two examples of metaphors are the condemnation of the proscribed with a spot and the conversation about bees in the parley.

After Julius Caesar’s death, Mark Antony formed a triumvirate with Lepidus and Octavius Caesar. A triumvirate is basically a power-sharing arrangement. One of the first things they did was institute what was known as proscription. This consisted of making a list of one’s enemies and then taking their property or killing them. In this case, the proscription list supposedly contained the names of those involved in the conspiracy to assassinate Caesar.

In the beginning of Act 4, the triumvirate meets to discuss the proscription list. Shakespeare uses this opportunity to portray the three men as callous and opportunistic. We see a different side of Mark Antony here, when he easily condemns his nephew to death.

LEPIDUS

Upon condition Publius shall not live,
Who is your sister's son, Mark Antony.

ANTONY

He shall not live; look, with a spot I damn him.
But, Lepidus, go you to Caesar's house;
Fetch the will hither, and we shall determine
How to cut off some charge in legacies. (Act 4, Scene 1) 

When Antony says “with a spot I damn him,” he is using a metaphor. The spot is Publius’s position on the proscription list. By checking off Publius, Antony condemns him to death. He makes light of the situation with this turn of phrase, possibly to make a show of his ruthlessness for the other triumvirs. It appropriately demonstrates his callousness and cold-bloodedness.

Another example of an interesting metaphor from Act 5 comes during the parley. A parley is a battlefield conversation. The two sides meet under temporary truce and supposedly discuss terms. The parley between Antony, Octavius, Brutus, and Cassius is hardly productive.

CASSIUS

Antony,
The posture of your blows are yet unknown;
But for your words, they rob the Hybla bees,
And leave them honeyless.

ANTONY

Not stingless too.

BRUTUS

O, yes, and soundless too;
For you have stol'n their buzzing, Antony,
And very wisely threat before you sting. (Act 5, Scene 1)

Cassius's metaphor comparing Antony’s words to flowers humorously turns the parley into a verbal jousting match. Antony thrusts Cassius’s words back on him with his comment about taking the stings away from the bees (the enemy), and Brutus extends the metaphor by commenting that Antony is all talk.

What does Helen Keller mean in her book The Story of My Life, when she says "'Light! Give me light!' was the wordless cry of my soul?"

In her autobiography, The Story of My Life, Helen Keller is well-known for her poetic use of language to express herself. After an illness, and having been left blind and deaf at the age of nineteen months, Helen struggles for several years to make herself understood, and is constantly frustrated at her futile attempts to communicate like the rest of her family appear to do. She even puts on her father's glasses and holds the newspaper in front of her eyes because she knows her father does that, but of course her attempts do not help and only serve to increase her frustration. 

When Annie does arrive to tutor Helen, Helen recalls in chapter 4 that it is "the most important day I remember in all my life" because it changes everything. Helen is desperate to learn and to be a part of the world she knows exists but has no access to and this is why she says "'Light! give me light!' was the wordless cry of my soul..." Helen has no words, no vocabulary because she has never been able to learn to speak. Her "wordless" cry reveals her inability to make herself understood. Light is also something that eludes Helen and she recognizes that the key to everything is language and understanding, something she feels that Annie Sullivan will be able to give to her; hence, Helen adds that "the light of love shone on me in that very hour."

In the book, she makes numerous references to the "soul," recognizing that, for her, it is the link between the "darkness" which fills her head and the "light" or real learning which will be responsible for her "soul's sudden awakening" (chapter 5) after the arrival of Annie Sullivan. 

`5x + 2y = 16, 3x - 5y =- 1` Find the angle theta (in radians and degrees) between the lines

Given

`5x+2y=16`  

`3x-5y=-1`

Find the slope of line 1.

`5x+2y=16`

`2y=-5x+16`

`y=-5/2x+8`

The slope of line 1 is `m_1=-5/2.`

Find the slope of line 2.

`3x-5y=-1`

`-5y=-3x-1`

`y=3/5x+1/5`

The slope of line t is `m_2=3/5.`

Find the angle between the lines using the formula

`tan(theta)=|(m_2-m_1)/(1+m_1m_2)|`

`tan(theta)=|((3/5)-(-5/2))/(1+(-5/2)(3/5))|=31/5`

`theta=tan^-1 (31/5)=80.8^@=1.4109`  radians.

The angle between the lines is 80.8 degrees or 1.4109 radians.

How do winter and summer affect the length of days at the equator?

The axis of rotation of the earth is not perpendicular to its orbital plane. The North Pole is tilted towards the sun for half the year and the South Pole is tilted towards the sun during the other half. As a result of this, the length of days during summer and winter change as we move towards the poles from the equator. At the equator, the length of days remains approximately the same during summer as well as winter and the time difference between sunrise and sunset is 12 hours throughout the year. As the earth moves around the sun its orbital distance from the sun is not the same as the orbit is not a circle. At the peak of summer at the equator, the earth is closest to the sun, and when the earth is farthest from the sun it is winter at the equator.

In Things Fall Apart, what points demonstrate that the Oracle's decisions are final?

The role of the Oracle of the Hills and the Caves within the Umuofian tribe is the most unquestionably powerful force within the region. She is the ultimate authority in the clan, and her decisions are final. The Oracle serves as a mediator between the tribe and their gods; thus, her will and proclamations are not to be debated. Indeed, she is so powerful that the clan will not go to war without her blessing:

“And in fairness to Umuofia it should be recorded that it never went to war unless its case was clear and just and was accepted as such by its Oracle--the Oracle of the Hills and the Caves. And there were indeed occasions when the Oracle had forbidden Umuofia to wage a war. If the clan had disobeyed the Oracle they would surely have been beaten, because their dreaded agadi-nwayi would never fight what the Ibo call a fight of blame” (12).

Another striking instance that shows her power and influence among the members of the tribe is when she decrees that the young captive Ikemefuna must die. Ezeudu warns Okonkwo not to take part in the slaying of Ikemefuna, but does not question the Oracle’s decision:

“Yes, Umuofia has decided to kill him. The Oracle of the Hills and the Caves has pronounced it. They will take him outside Umuofia as is the custom, and kill him there. But I want you to have nothing to do with it. He calls you his father” (57).

These are just two happenings that illustrate the Oracle’s absolute power within the Umuofian community.

In the novel, The Boy in the Striped Pajamas, what is one technique that could be used to express innocence and friendship?

Literary techniques help writers explain their message and allow readers to understand, analyze, and draw their own conclusions. In The Boy in the Striped Pajamas, one literary technique that is used to reveal Bruno's innocence and the theme of friendship and which is crucial in the reader's understanding of the story, is inference. Two examples which occur throughout and which reveal Bruno's innocence are in his mispronunciation of "Out-With" and "The Fury." The reader is expected to know that these refer to Auschwitz and the fuhrer but Bruno has no idea of the importance of either. Bruno thinks that the Nazi salute he is expected to make is a greeting and is no more offensive than saying "have a pleasant afternoon," (chapter 5).

When Bruno describes the people in the "striped pajamas" as "extraordinary," the reader makes the connection between the significance of the title and what is about to unfold. Bruno will never know the cost of his friendship with Shmuel, even as he stands in what is apparently the gas chamber and holds hands with his "best friend(s) for life." Bruno thinks that the march and the dark room must have something to do with the poor weather conditions and "stopping people from catching colds" (chapter 19) because his father is the commandant and so Bruno's trust is unwavering and his innocence is unmistakable as he would never expect his father to be instrumental in anything as cruel and unnecessary. He may not understand his father but never doubts his intentions.

What school choice might you make after attending the emergency relocation plan meeting?

The emergency relocation meeting occurs after a good portion of Paul’s middle school, Lake Windsor Downs, is destroyed by a sinkhole. The students are given two options. They can either attend Lake Windsor Downs on an altered schedule that makes school last far longer into the afternoon and evening, or they can transfer to Tangerine Middle School for the remainder of the year.

To properly consider the question, it’s important to know more about Tangerine Middle School. Tangerine Middle School is known for its lack of resources, as well as  the presence of gangs and other criminal elements. Students from Lake Windsor Downs often unfairly stereotype Tangerine Middle School students by saying that Tangerine students bring guns to school; while Tangerine probably isn’t that dangerous, its students did vandalize one of the exhibits at the town’s carnival. They’re also known for being particularly vicious during sports games. However, Tangerine has plenty of positive elements. For example, it is more racially diverse than Lake Windsor Downs. Its teachers are motivated and caring, as well as more likely to assign projects than force students to read out of the textbook. Additionally, once a kid gains the respect of Tangerine’s toughest students, he or she will have friends for life.

Lake Windsor Downs has different, but no less severe, problems. It’s a wealthy school with plenty of resources. Its students are likely to come from families who recently moved to Tangerine and now live in the new housing developments. However, this contributes to a lack of unity since many students don’t share childhood experiences and a sense of place with their classmates.  Additionally, the Lake Windsor Downs principal and counselors can often be inflexible and insensitive to students’ needs, as shown by their refusal to take away any sections of Paul’s IEP. Additionally, despite its wealth, Lake Windsor Downs did not provide safe classrooms for its students. This definitely shows a lack of priorities!

When deciding personally for yourself, it’s important to remember that while Tangerine Middle School is the perfect school for Paul, it’s probably not the perfect school for the average student. Tangerine is perfect for Paul because it lets him shed his IEP and make a new beginning. Therefore, if I was a student who was currently unhappy at Lake Windsor Downs, I’d likely to choose Tangerine. If I was a student satisfied with life in Lake Windsor Downs, I’d remain there and keep the “status quo.”

What is growth?

Process and Effects

The human body grows from conception until adult size is reached. Adult size is reached in females around the age of eighteen and in males around twenty or twenty-one, but there is considerable variation in either direction. (Nearly all numerical measurements of growth and development are subject to much variation.) On the average, males end up with a somewhat larger body size than females because of these two or three extra years of growth.

Growth begins after conception. The first phase of growth, including approximately the first month after conception, is called embryonic growth, and the growing organism is called an embryo. During embryonic growth, the most important developmental process is differentiation, the formation of the various organs and tissues. After the organs and tissues are formed, the rest of prenatal growth is called fetal growth and the developing organism is called a fetus. Respiratory movements begin around the eighteenth week of gestation, during the fetal stage; limb movements (such as kicking) begin to be felt by the mother around the twenty-fourth week, with a considerable range of variation. At birth, the average infant weighs about 3.4 kilograms (7.5 pounds) and measures about 50 centimeters (20 inches) in length.

Growth continues after birth and throughout childhood and adolescence. From the perspective of developmental biology, childhood is defined as the period from birth to puberty, which generally begins at twelve years of age, and adolescence continues from that point to the cessation of skeletal growth at around the age of eighteen in females and twenty or twenty-one in males. The long period of adulthood that follows is marked by a stable body size, with little or no growth except for the repair and maintenance of the body, including the healing of wounds. After about age sixty, there may be a slight decline in body height and in a few other dimensions.

By one year of age, the average baby is seventy-five centimeters (thirty inches) long and weighs ten kilograms (tewnty-two pounds). (There is actually a slight decline in weight in the first week of postnatal life, but this is usually regained by age three weeks.) For ages one to six, the average weight (in kilograms) can be approximated by the equation“weight = age 2 + 8.” For ages seven to twelve, growth takes place more rapidly: Average weight (in kilograms) can be approximated by “weight = age 3.5 - 2.5,” while average height (in centimeters) can be approximated for ages two to twelve by the equation “height = age 6 + 77.” Head circumference has a median value of about 34.5 centimeters at birth, 46.3 centimeters at an age of one year, 48.6 centimeters at age two, and 49.9 centimeters at age three. All these figures are about one centimeter larger in boys than in girls, with considerable individual variation. Median heights and weights, when differentiated by sex, reveal that boys and girls are generally similar until age fourteen, after which boys continue to gain in both dimensions.

Growth of the
teeth takes place episodically. In most children, the first teeth erupt between five and nine months of age, beginning with the central incisors, the lower pair generally preceding the upper pair. The lateral incisors (with the upper pair first), the first premolars, the canines, and the second premolars follow, in that order. All these teeth are deciduous teeth (“baby teeth”) that will eventually be shed, to be replaced during late childhood by the permanent teeth. At one year of age, most children have between six and eight teeth.

Growth takes place in several directions. Growth at the same rate in all directions is called isometric growth, which maintains similar proportions throughout the growth process. Isometric growth occurs in nautilus shells and a variety of other invertebrates. Most of human growth, however, is allometric growth, which takes place at different rates in different directions. Allometric growth results in changes in shape as growth proceeds. Moreover, different parts of the body grow at different rates and in different directions. During fetal development, for example, the head develops in advance of the fore and hind limbs, and the fetus at about six months of age has a head which is about half its length. The head of a newborn baby is about one-third of its body length, compared to about one-seventh for an adult. In contrast, the legs make up only a small part of the body length in either the six-month-old fetus or the newborn baby, and their absolute length and proportionate length both increase throughout childhood and adolescence.

Growth of the skeleton sets the pace for growth of the majority of the body, except for the nervous system and reproductive organs. Most parts of the skeleton begin as fast-growing cartilage. The process in which cartilage tissue turns into bone tissue is called ossification, which begins at various centers in the bone. The first center of ossification within each bone is called the diaphysis; in long bones, this ossification usually takes place in the center of the bone, forming the shaft. Secondary centers of ossification form at the ends of long bones and at certain other specified places; each secondary center of ossification is called an epiphysis. In a typical long bone, two epiphyses form, one at either end. Capping the end of the bone, beyond the epiphysis, lies an articular cartilage. Between the epiphysis and the diaphysis, the cartilage that persists is called the epiphyseal cartilage; this becomes the most rapidly growing region of the bone. During most of the growth of a long bone, the increase in width occurs by accretion, a
gradual process in which material is added at a slow rate only along a surface. In the case of a bone shaft, increase in width takes place only at the surface, beneath the surrounding membrane known as the periosteum. By contrast, the epiphyseal cartilage grows much more rapidly, and it also grows by interstitial growth, meaning that growth takes place throughout the growing tissue in all directions at once. As the epiphyseal cartilage grows, parts of it slowly become bony, and those bony portions grow more slowly.

During the first seven or eight years of postnatal life, the growth of the epiphyseal cartilage takes place faster than its replacement by bone tissue, causing the size of the epiphyseal cartilage to increase. Starting around age seven, the interstitial growth of the epiphyseal cartilage slows down, while the replacement of cartilage by bone speeds up, so that the epiphyseal cartilage is not growing as fast as it turns into bone tissue; the size of the epiphyseal cartilage therefore starts to decrease. At the time of puberty, the hormonal influences create an adolescent growth spurt during which the individual’s bone growth increases for about a one-year period. In girls, the adolescent growth spurt takes place about two years earlier than it does in boys—the average age is around twelve in girls, versus about fifteen in boys—but there are tremendous individual variations both in the extent of the growth spurt and in its timing. By age fourteen, most girls have already experienced most of their adolescent growth spurt, while most boys are barely beginning theirs. Consequently, the average fourteen-year-old girl is a bit taller than the average fourteen-year-old boy.

At around eighteen years of age in females and twenty or twenty-one years of age in males, the replacement of the epiphyseal cartilage by bone is finally complete, and bone growth ceases. The age at which this occurs and the resulting adult size both vary considerably from one individual to another. For the rest of adult life, the skeleton remains more or less constant in size, diminishing only slightly in old age.

Most of the other organs of the body grow in harmonious proportion with the growth of the skeleton, reaching a maximum growth rate during the growth spurt of early adolescence and reaching a stable adult size at around age eighteen in women and age twenty or twenty-one in men. The nervous system and reproductive system, however, constitute major exceptions to this rule. The nervous system and brain grow faster at an earlier age, reaching about 90 to 95 percent of their adult size by one year of age. The shape of the head, including the shape of the skull, keeps pace with the development of the brain and nervous system. For this reason, babies and young children have heads that constitute a larger proportion of their body size than do the heads of adults.

The growth of the
reproductive system also follows its own pattern. Most reproductive development is delayed until puberty. The reproductive organs of the embryo form slowly and remain small. The reproductive organs of children, though present, do not reach their mature size until adolescence. These organs, both the internal ones and the external ones, remain small throughout childhood. Their period of most rapid growth marks the time of puberty, which spans ages eleven through thirteen, with a wide range of variation. At this time, the
pituitary gland begins secreting increased amounts of the follicle-stimulating hormone (FSH), which stimulates the growth and maturation of the gonads (the ovaries of females and the testes of males). The ovaries or testes then respond by producing increased amounts of the sex hormones testosterone (in males) or estrogen (in females), which stimulate the further development of both primary and secondary sexual characteristics. Primary sexual characteristics are those which are functionally necessary for reproduction, such as the presence of a uterus and ovaries in females or the presence of testes and sperm ducts in males. Secondary sexual characteristics are those which distinguish one sex from another, but which are not functionally necessary for reproduction. Examples of secondary sexual characteristics include the growth of breasts or the widening of the hips in females, the growth of the beard and deepening of the voice in males, and the growth of hair in the armpits and pubic regions of both sexes.

Growth takes place psychologically and socially as well as physically. Newborn babies, though able to respond to changes in their environment, seem to pay attention to such stimuli only on occasion. At a few weeks of age, the baby will respond to social stimuli (such as the sound of the mother’s voice) by smiling. Babies usually can grasp objects by five months of age, depending on the size and shape of the object. By six months, most babies will show definite signs of pleasure in response to social stimulation; this may include an open-mouth giggle or laugh. At seven months of age, most babies will respond to adult facial expressions and will show different responses to familiar adults as opposed to strangers. The age at which babies learn to crawl varies greatly, but most infants learn the technique by nine or ten months of age. Social imitation begins late in the first year of life. Also, by this time, children learn object permanence, meaning that they will search for a missing object if they have watched it being hidden. Walking generally develops around eighteen months of age, but the time of development varies greatly.

Jean Piaget
(1896–1980) was a pioneer in the study of the social and cognitive development of children. Piaget identified four stages of cognitive and social growth, which he called sensorimotor, preoperational, concrete operational, and formal operational. In the sensorimotor stage, from birth to about two years of age, infants begin with reflexes such as sucking or finger curling (in response to touching their palms). Starting with these reflexes, they gradually learn to understand their senses and apply the resulting information in order to acquire important adaptive motor skills that can be used to manipulate the world (as in picking up things) or to navigate about and explore the world (as in walking). Socially, infants develop ways to make desirable stimuli last by such acts as smiling. In the preoperational stage, which lasts from about two to six years of age, children acquire a functional use of their native language. Their imagination flourishes, and pretending becomes an important and frequent activity. Most of the thinking at the preoperational stage is egocentric, however, which means that the child perceives the world only from his or her own point of view and has difficulty seeing other points of view.

The concrete operational stage spans the years from about seven to eleven years of age. This is the stage at which children learn to apply logic to concrete objects. For example, they realize that liquid does not change volume when poured into a taller glass, and they develop the ability to arrange objects in order (for example, by size) or to classify them into groups (for example, by color or shape). The final stage is called the formal operational stage, beginning around age twelve. This is the stage of adolescence and adulthood, when the person learns to manipulate abstract concepts in such areas as ethical, legal, or mathematical reasoning. This is also the stage at which people develop the ability to construct hypothetical situations and to use them in arguments.

Complications and Disorders

Disorders of growth include dwarfism, gigantism, and several other disorders such as achondroplasia (chondrodystrophy). Dwarfism often results from an insufficiency of the pituitary growth hormone, also called somatostatin or somatotrophic hormone. Some short-statured individuals are normally proportioned, while others have proportions differing from those of most other people. An overabundance of growth hormone causes gigantism, a condition marked by unusually rapid growth, especially during adolescence. In some individuals, the amount of growth hormone remains normal during childhood but increases to excessive amounts during the teenage years; these individuals are marked by acromegaly, a greater than normal growth which affects primarily the hands, feet, and face.

Achondroplasia, also called chondrodystrophy, is a genetically controlled condition caused by a dominant gene. In people having this condition, the epiphyseal cartilages of the body’s long bones turn bony too soon, so that growth ceases before it should. Those exhibiting chondrodystrophy therefore have short stature and childlike proportions but rugged faces that look older than they really are.

Inadequate growth can often result from childhood malnutrition, particularly from insufficient amounts of protein. If a child is considerably shorter or skinnier than those of the same age, that child’s diet should be examined for the presence of malnutrition. Intentional malnutrition is one of the characteristic features of anorexia nervosa. The opposite problem, overeating, can lead to obesity, although obesity can also result from many other causes, including diabetes and other metabolic problems.

By the late twentieth century, human growth hormone, a drug used since the 1950s to help very short children grow, was being used for “off-label” purposes that included antiaging and body building. In 2002, researchers suggested an apparent link between the use of the hormone and cancer, specifically Hodgkin’s disease and colorectal cancer.

Perspective and Prospects

As a phenomenon, growth of both wild and domestic animals was well known to ancient peoples. Hippocrates (ca. 460–ca. 370 BCE), considered the founder of medicine, wrote a treatise on embryological growth, and Aristotle (384–322 BCE) wrote a longer and more complete work on the subject. During the Renaissance, Galileo Galilei (1564–1642) studied growth mathematically and distinguished between isometric and allometric forms of growth, arguing that the bones of giants would be too weak to support their weight.

The most important era in the study of human embryonic development was ushered in by the Estonian naturalist Karl Ernst von Baer (1792–1876), who discovered the human ovum. From this point on, detailed studies of human embryonic and postnatal development proceeded at a rapid pace, especially in Germany. Much of the modern understanding of growth in more general or mathematical terms derives from the classic studies of the British anatomist D’Arcy Wentworth Thomson (1860–1948). In the twentieth century, Piaget became a leader in the study of childhood social and cognitive growth phases.

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Tsiaras, Alexander, and Barry Werth. From Conception to Birth: A Life Unfolds. New York: Doubleday, 2002.

What internal conflict causes Daisy to reject Gatsby in the hotel room?

It is reasonable to assume that Daisy has love for Jay Gatsby; they have a history together that predates her marriage to Tom, and readers understand that she was very conflicted on the eve of her marriage when she learned that Jay Gatsby still loved her.  It is also reasonable to assume that Daisy is telling the truth when she confesses to Jay that she loved Tom, too.  Daisy's internal conflict seems to be that she genuinely has feelings for both men.  Ultimately, however, Tom correctly predicts that Daisy will not leave him for a man who is an admitted criminal.  Because Daisy has always enjoyed "old money" status, from her girlhood and her marriage, she can't sacrifice the security that Tom's social position offers her.  Daisy cares too much about her reputation to become a gangster's wife.

How does James Joyce use Irish history and Irish politics in his novel A Portrait of the Artist as a Young Man? Please explain.

James Joyce was obsessed with both Irish history and Irish politics, and he used the two topics extensively in all of his works. In his novel A Portrait of the Artist as a Young Man, one of the most famous examples of Joyce's use of politics and history is the Christmas dinner in the first chapter, in which Stephen's family discusses and debates the tragic downfall of Charles Stewart Parnell. 

During the Christmas dinner, Stephen witnesses a debate about Parnell, a prominent Irish Nationalist politician. To properly understand this debate, it's important to understand Parnell within a historical and political context. Parnell was an Irish member of the British Parliament and was popular in Ireland in the late 1800's due to his commitment to fighting for Irish Home Rule, a political movement that sought to return significant sovereignty to the Irish state. Parnell was thus seen as an Irish savior, one who would fight against the tyranny of Great Britain and lead Ireland to independence. Parnell was ruined by scandal, however, during 1889-90, during which time it was revealed that he had been engaging in an affair with a married woman, Katherine O'Shea. Ireland's conservative Catholic culture was scandalized, and Parnell was died a short time later in disgrace. 

With this knowledge in mind, the Christmas dinner makes much more sense. In this scene, members of Stephen's family argue about the Parnell affair; some of them uphold their leader, while others condemn him. This argument illustrates an important historical and political divide in Irish history and politics during the 20th century, and it also exemplifies how important both topics are to understanding Joyce. While Joyce's work is often seen as avant-garde, the author rooted his writing firmly within a specific historical and political context, and so it is necessary to understand this context if one is to fully understand his work.