Why does the poem refer to the hammer and the anvil?

In "The Tyger," the speaker asks the tiger who or what could have made him. Noting the phrase "immortal hand," the suggestion is that the speaker is asking the tiger what kind of god would create such a fearsome creature. In Blake's companion poem, "The Lamb," he also asks the Lamb "who made thee?" In this poem, the speaker heaps praise upon the Lamb, a reference to Christ. 

In the "Tyger," the speaker asks "Did he who made the Lamb make thee?" In other words, the speaker is befuddled that a god who could make something so gentle (Lamb) could also make something so ferocious. One could construe a metaphor from this. If God can make such beautiful and peaceful things then why does he allow destructive things to exist as well. This is a repeated theme in some of Blake's other poems: that of oppositions. 

The speaker uses the hammer and anvil as a way to reference the work of a blacksmith. Just as the blacksmith creates hard, sometimes dangerous objects with the hammer and anvil, some "immortal hand" has forged a dangerous creature: the tiger. Blake uses blacksmith imagery of fire and steel to highlight the tiger's strength and ferocity. 

Examine the novel Gulliver's Travels as a satire on humankind in general.

Gulliver's time with the Lilliputians really puts a spotlight on quite a few of humankind's flaws.  For example, the debate between the Big Endians and the Little Endians centers on which side of the egg a person should crack: it's completely ridiculous.  However, this conflict satirizes the wars between Catholics and Protestants in England at this time, making the violence seem both unnecessary and ridiculous.  Why should it affect me if you want to crack your egg on the other side than I do?  It doesn't.  Likewise, why should it affect you if I want to practice Protestantism and you are a Catholic?  It doesn't.  Humans, in general, have a tendency to fight over basic ways of life rather than simply live and let live.  A fair point.

In Brobdingnag, the king's perspective on Gulliver and his countrymen leads to some rather harsh, but fair, criticisms of humankind.  The king, having listened to Gulliver's tales of wars, religious schisms, political parties, etc., observes "how contemptible a Thing was human Grandeur."  He even makes fun of how seriously we take ourselves given how completely ridiculous we are.  He ends up believing that humankind is essentially "quarrelsome" and prone to all manner of sinful and hurtful behavior, and he refers to us as "little odious Vermin" who, frankly, contribute nothing of value to the earth at all.  

In the third book, Gulliver travels to many locations, each one satirizing humankind in a myriad of ways.  His visit to Laputa, for example, shows us to be selfish creatures who are so self-centered that we can get lost inside our heads and forget to even recognize the presence of another person (satirized by their need to have someone strike them in the face when it is their turn to speak, or the ear when they need to be sure to listen).  The experiments performed at the Academy of Lagado seem to satirize the Royal Society of London for encouraging misguided experiments that would amount to no real benefit for humankind, but that we seem to do because we forget that science should have some useful application.  In Luggnugg, he learns of humanity's error in wishing we could live forever when he meets the Struldbrugs, a race of miserable immortals who would rather die than live as they do; implication: we wish for things without considering their consequences.  

In the final book, the similarities between Yahoo and human should be a bit too close for comfort.  These disgusting creatures are the worst: they are so selfish that, even when there is more than enough food to go around, each will try to make off with as much as he or she can out of sheer greed.  They are unreasonably attracted to shiny objects and will kill their peers to obtain such an object of desire.  They are savage, odious animals that are worth little and contribute less.  All in all, a pretty harsh criticism of humanity, but not entirely without merit.

In Crispin: The Cross of Lead by Avi, why does Crispin feel that God has abandoned him?

As John Aycliffe and his men chase Crispin, the young boy runs for his life. However, Crispin manages to elude his would-be captors after swimming across the millrace (a ditch filled with river water that turns the mill's wheels) and making his way to the southern end of Stromford.

Crispin is so intent on escaping the clutches of Aycliffe and his men that he almost misses Father Quinel's body on the road. It is only when he kneels down to pray that he sees the priest's body on the ground. When he turns the body over, he realizes to his horror and grief that the priest has had his throat slit and is dead. It is right after this ghastly discovery that Crispin feels as if God has abandoned him. He likely feels this way because everyone he has ever loved and trusted is now dead.

At present, he has no one he can depend on to protect him and to keep him safe from capture and certain death. He can see no future for himself but that of 'an early death and an unmarked grave.' He reasons that he will also likely end up in Hell, as there will be no priests to perform the sacred last rites of his faith. Because he thinks that his situation is hopeless, Crispin feels that God has largely abandoned him. Despite his despair, however, he finds himself again entrusting his safety to God.

What is sibling rivalry?

Causes and Symptoms

Sibling rivalry is the competition or jealousy that develops between siblings for the love, affection, and attention of either one or both parents. The concept of sibling rivalry has been discussed for centuries, and it is considered a universal phenomenon in families. Although sibling rivalry is generally described in terms of its negative aspects, healthy competition between brothers and sisters can be useful in the individual development of necessary social, communication, and cognitive skills.

While the dynamics of the ways in which brothers and sisters relate to one another cannot be reduced to specifics of age, birth order, gender, and family size, these family constellation variables are important in the development of sibling rivalry. While each element will be discussed separately, it is important to take into account all the relevant factors when looking at causes of sibling rivalry.

The ages of siblings and their birth order are significant factors that have been related to sibling competition. There are many stereotypes associated with being the oldest, youngest, and middle child in the family. For example, typical firstborn children tend to be highly organized and responsible, while youngest children are likely to benefit from more experienced, relaxed parenting and may be more affectionate and spontaneous. Middle children are often more difficult to characterize. They may be at more risk than other children for receiving less attention, and they tend to develop stronger relationships outside the family. Using these stereotypical characteristics as guides for assessing a particular child, it is possible to speculate on the relevance of birth order and age in the development of sibling competition.

The effects of spacing between children has also given rise to a number of theories. It is generally accepted that the closer siblings are in age, the more similar their life experiences are likely to be. As they may have more in common, siblings close in age are also more likely to struggle with each other more frequently. For this reason, siblings who are close in age may engage in more competition with each other than siblings who are separated by more than a few years.

The gender of siblings is also a variable in the development of sibling relationships, including sibling competition. Siblings help each other discover some of the basic characteristics of male and female roles. Growing up with all brothers or all sisters can teach a child much about dealing with one gender. Having a sibling of the opposite sex can offer a child valuable initial information about the opposite sex. The attitudes of parents regarding gender roles also influence the relationships between siblings. Parents who display favoritism toward children based on gender may contribute to sibling jealousy and competition.

For a wide variety of reasons, specific children may be more emotionally vulnerable to feelings of jealousy than their siblings at a given time. For example, in a family with a child who has a disability, other siblings may feel that they do not receive as much attention, or the child with special needs may feel different and unwanted.

Emotionally vulnerable children are frequently found in families experiencing high levels of stress. There is evidence that the emotional climate within the family is directly linked to the quality of sibling relationships. It then follows that sibling rivalry may be more problematic in families where there are stressors such as marital conflict, chronically ill family members, or unwanted extended family involvement.

The competition that emerges between siblings can be for material resources such as toys or space within the household. For example, it is not uncommon for an older child to resent having to share a room with a younger brother or sister. Frequently, the competition for material resources stems from a child’s uncertainty regarding his or her status in the family. Children may interpret the need to share space as an indication of their lesser importance to parents.

Jealousy can develop when a child perceives favoritism on the part of a parent. This jealousy results from a lack of equality in treatment. Not only is the less favored child at risk for feeling jealous, but the parental favorite often does not perceive the extra attention as pleasant or comfortable. The challenge in parenting is trying to achieve equality when children are each exceptional beings with their own individual needs. In her book Dr. Mom’s Parenting Guide (1991), Marianne Neifert recommends loving children “uniquely,” giving each child the message that his or her place in the family is a special one. A parent who consistently favors one child over another through the amount of love and attention shown is encouraging unhealthy rivalry between the children.

Sibling rivalry can manifest itself in a variety of ways. When a new sibling is born, an older child may be either openly or passively hostile to the new baby. This hostility can be displayed in the form of direct verbal or physical attacks on the baby. Sometimes children request that parents return the infant to the hospital or give it away. In other cases, a child may act up or demand attention when the parent is busy with the infant. Serious abuse by siblings is rare, but even mild incidents need attention by parents.

Some children react to a new sibling by displaying regressive behavior such as bed-wetting, asking to be carried, thumb-sucking, excessive crying, or talking baby talk. Other negative behaviors associated with sibling jealousy are lying, aggressiveness, or destructive behaviors. It is also typical for the child to vent frustration or anger on other individuals, pets, or toys when feeling jealous of a sibling. In older children, sibling rivalry may be exhibited by taking the younger child’s toys or demanding more parental attention. Another example of rivalry in older children includes a drive to outperform the other sibling in academic or athletic settings.

Unless managed effectively by parents, feelings of jealousy and competition among siblings can undermine a child’s development and may continue into adult relationships. Sibling rivalry can be minimized by the active involvement of parents in setting appropriate rules for dealing with conflicts.

Treatment and Therapy

The negative impact of sibling rivalry can be minimized through parental education and attention to the conditions that intensify sibling competition. Attending to the development of a relationship between siblings is an ongoing process that parents can enhance through their involvement in helping children develop good interpersonal skills.

The foundation for dealing effectively with sibling rivalry is an awareness and understanding that sibling competition is a normal, healthy part of family life. Rivalry develops between siblings in nearly every family, and it becomes problematic only when taken to extremes or when ignored and allowed to escalate.

The common behavior problems associated with sibling rivalry occur in the context of many interacting factors: parental expectations; the child’s developmental level; the temperament of a particular child; parental discipline; family constellation characteristics such as age, gender, and spacing of children; and the presence of extended family members. There is growing evidence regarding the importance of obtaining assessments and information from family members (including extended family) and other sources such as school or day care personnel when identifying a problem of sibling rivalry.

One of the situations in which parents express the most open concern regarding sibling rivalry is when a new baby is expected or an adoption of a child is imminent. When a new sibling is expected, the other children can be invited to be actively involved in the preparation. Age-appropriate discussions with each child about pregnancy or adoption are good preventive measures. Parents should be available to answer questions regarding the changes to be expected with the arrival of the additional child. An open, direct discussion with older children can minimize the adjustment difficulties and address initial concerns. Children need regular verbal and demonstrated assurances that they will continue to be loved following the arrival of a new sibling.

Parents can involve an older child in the care of a baby as a means of acknowledging the unique contributions of that child. Expecting an older child to be a regular caretaker, however, may create additional problems and place unnecessary stress on the older brother or sister.

While some older children exhibit negative behaviors associated with the arrival of a baby, others respond positively by becoming more mature and autonomous. Focusing on the individual contributions of an older sibling can minimize the feelings of jealousy when a new child enters the family.

Parents should avoid making either overt or subtle comparisons between siblings and instead focus on the special qualities and achievements of each child. As Neifert suggests, “honor the individual in every child.” This is sometimes difficult to accomplish, as many times parents anticipate that subsequent children will be similar to their firstborn. For example, if a first child is successful in sports, a parent may anticipate that the younger sibling will also be athletically inclined. Such unrealistic expectations can foster unhealthy competition and put needless pressure on a younger sibling.

Jealousy between brothers and sisters seldom ends with the adjustment of a new family member and the acknowledgment that an “only” child now has to share parental attention. Balancing the emotional needs of two or more children of differing ages continues to be an important concern of parents as children move through different developmental stages.

The negative behaviors associated with sibling rivalry can stem from other sources as well. Sometimes siblings fight because they are bored or have few appropriate alternatives to taunting a sibling. Sometimes the behavior can be a reaction to stressors outside the home, such as problems at school or socialization difficulties. A parent’s reaction to negative behavior will have a large impact on whether the behavior continues. Parents who can model effective interpersonal skills themselves are likely to influence the development of these same skills in their children.

When jealous behaviors are displayed by siblings, parents need to be sensitive to the source of the feelings. The cause of the competition or rivalry should be the focus of parental interventions, rather than the negative behavior itself. Children should be encouraged to talk about their feelings openly, and parents need to be willing to acknowledge and validate those feelings for each child. After allowing children to express their feelings and showing appreciation for the difficulty of the problem, parents can encourage siblings to work toward a mutual resolution.

One of the common manifestations of sibling rivalry is the expression of anger and, sometimes, the physical or verbal abuse that accompanies the anger. While common, violent displays of anger are not appropriate. Helping children learn to handle anger responsibly is an important task for parents.

In handling fighting between children, parents must assess the level of conflict and intervene appropriately when necessary. Normal bickering between siblings that does not include verbal abuse or threats of physical abuse rarely requires parental involvement. If the situation worsens, however, the following steps can be useful for parents: acknowledge the angry feelings of each child, then reflect each child’s point of view; describe the problem from the position of a respectful bystander, without taking sides on the issue; and express confidence that the children can come up with a reasonable solution.

Parents need to be actively involved in promoting a system of justice within the family that includes age-appropriate rules and consequences for behavior. Examples of ways that parents can manage the behavior are separating siblings when a situation appears dangerous and redirecting children’s activities when aggression is likely to occur. Parents can also take responsibility for encouraging and rewarding cooperative play and for providing children with appropriate, nonaggressive models for resolving conflict.

Teaching children conflict resolution strategies is an important way for parents to intervene in sibling rivalry problems. Developing the ability to express one’s feelings is a valuable step toward conflict resolution. Children should be encouraged to put their feelings into words in appropriate ways. Young children may need help in doing so through the use of statements such as, “You don’t like it when I spend so much time caring for your baby sister, do you?” Granting a child permission to fantasize about a given situation may also help in diffusing angry feelings. Encouraging children to verbalize what they wish would happen allows them to address emotions in an honest way. Children should be taught from an early age to develop creative ways to vent their anger. Children can be taught to use physical exercise, write feelings in a journal, or go to their rooms to cool down as appropriate ways to manage anger.

Managing sibling conflict is complex in any family, but even more so in situations where there is a single parent or a blending of families through divorce and remarriage. Because sibling competition stems from a child’s anxiety about sharing parental attention, the presence of a single parent can intensify the feelings of insecurity about one’s position in the family. Single parents need to be careful not to turn a child into a spouse substitute, instead viewing each child as a unique individual who deserves to be able to mature at his or her own pace. Extended family members, including grandparents, aunts, and uncles, may be useful in helping a single parent meet the individual needs of each child in the family.

When parents remarry, children are required to make adjustments in their relationships and to include new people in their family. Children need to be allowed to express their ambivalent feelings regarding stepsiblings and half siblings, as these feelings are a normal part of this adjustment process. Parents need to accept and tolerate each child’s feelings, as long as guidelines of justice and safety are recognized.

Childhood rivalries between siblings can be revived in adulthood, especially when children must come together to make decisions about aging parents. Feuds erupt easily between brothers and sisters over complicated issues such as who should have the most control over belongings, medical care, and finances. In some cases, rivalries are increased when the decision is made to take the parent in to one of the siblings' home rather than place him or her in a care facility.

Despite the abundant research available on the topic of sibling rivalry, there is still much that is unknown regarding the complex relationships between brothers and sisters. While it is possible to look at generalizations regarding the issues important in sibling rivalry, it is not possible to predict adjustment or maladjustment in a particular child. Information must be gathered from a number of sources and evaluated for each child when planning a course of action to address concerns about sibling rivalry.

Perspective and Prospects

Through the ages, people have assumed that jealousy and rivalry are unavoidable characteristics of sibling relationships. Sibling rivalry is a common theme in several classic stories. In the Bible, the competition between brothers Cain and Abel and the jealousy that develops between Joseph and his brothers over issues of parental favoritism are but two accounts of sibling rivalry. Such accounts support the assertion that jealousy among siblings is a common phenomenon.

Sigmund Freud’s theory of socialization was one of the first to address the concept of sibling rivalry from a scientific perspective. According to Freud, sibling rivalry, with its struggles and controversy, is inherent in all brother-and-sister relationships. Much of what Freud hypothesized regarding sibling competition was grounded in a personal understanding of his own relationships with his siblings. Freud was the oldest child in a family that included five younger sisters and a younger brother.

Competition for parental attention is a dominant theme in Freud’s description of the sibling relationship. His description emphasizes the negative emotions associated with sibling relationships and concludes that, although these feelings diminish as children mature, the rivalry persists into adulthood. Few of his remarks about sibling relationships address gender differences, as Freud described relationships from his own perspective as a male. Therefore, he was also a firm believer in the idea of the Oedipus complex, in which male children inherently feel sexual impulses toward their mother and subsequent jealously toward their father—which could extend to heightened competition with siblings as well.

Another theorist who addressed the issue of sibling relationships was Walter Toman. In 1961, Toman published the book Family Constellation: Theory and Practice of a Psychological Game. The book suggests that birth order, gender, and spacing are significant factors in the development of personality and strongly influence the nature of personal relationships both within and outside the family of origin. Toman details eight sibling positions, such as oldest brother of brothers, youngest sister of brothers, and so on. While the generalizations presented in Toman’s work have significance as a basis of comparison, there are too many intervening variables and complexities in family life to use birth order theories as complete explanations for sibling relationships and family roles. Birth order, gender, and spacing are several of the many significant factors that shape the connections between siblings.

Sibling relationships play an important role in each child’s development. Since the works of Freud and Toman were published, researchers have expanded their studies of sibling rivalry to include the broader context of the family. There is growing evidence that the emotional climate of the family is directly related to the quality of the relationship of siblings. The parental relationship, factors of vulnerability in specific children, parental expectations, and family constellation variables each contribute to the development and intensity of sibling rivalry between brothers and sisters in a given family.

Bibliography

"Adoption and Sibling Rivalry." HealthyChildren.org. Amer. Academy of Pediatrics, 6 Jan. 2015. Web. 13 Feb. 2015.

Berk, Laura E. Child Development. 9th ed. Boston: Pearson Education, 2013. Print.

Boer, Frits, and Judy Dunn, eds. Children’s Sibling Relationships: Developmental and Clinical Issues. Hillsdale: Erlbaum, 1992. Print.

Colt, George Howe. "Sibling Rivalry: One Long Food Fight." New York Times. New York Times, 24 Nov. 2012. Web. 13 Feb. 2015.

Goldenthal, Peter. Beyond Sibling Rivalry: How to Help Your Children Become Cooperative, Caring, and Compassionate. New York: Holt, 2000. Print.

Greydanus, Donald E., Dilip R. Patel, and Helen D. Pratt, eds. Behavioral Pediatrics. 2 vols. 3rd ed. New York: Nova Biomedical, 2009. Print.

Kramer, Laurie, and Chad Radey. “Improving Sibling Relationships Among Young Children: A Social Skills Training Model.” Family Relations 46.3 (1997): 237–46. Print.

Leder, Jane Mersky. Brothers and Sisters: How They Shape Our Lives. New York: Ballantine, 1994. Print.

Mendelson, Morton J. Becoming a Brother: A Child Learns About Life, Family, and Self. Cambridge: MIT, 1990. Print.

Neifert, Marianne E. Dr. Mom’s Parenting Guide: Commonsense Guidance for the Life of Your Child. New York: Dutton, 1996. Print.

Norton, Amy. "Sibling Bullying Can Lead to Depression, Anxiety in Victims. U.S. News & World Report. U.S. News & World Report, 17 June 2013. Web. 13 Feb. 2015.

Pendley, Jennifer Shroff. "Sibling Rivalry." KidsHealth. Nemours Foundation, Aug. 2012. Web. 13 Feb. 2015.

Sulloway, Frank J. Born to Rebel: Birth Order, Family Dynamics, and Creative Lives. New York: Random, 1997. Print.

Toohey, Peter. "Sibling Rivalry, a History." Atlantic. Atlantic Monthly, 30 Nov. 2014. Web. 13 Feb. 2015.

Ziegahn, Suzen J. The Stepparent’s Survival Guide: A Workbook for Creating a Happy Blended Family. Oakland: New Harbinger, 2003. Print.

What is glutathione as a therapeutic supplement?

Overview

Dangerous naturally occurring substances in the body called free radicals
pose a risk to many tissues. The body deploys an antioxidant defense system to
hold free radicals in check. Glutathione, a protein made from the amino acids
cysteine, glutamic acid, and glycine, is one of the most important elements of
this system.

Glutathione does much of its work in the liver, although it is also found elsewhere in the body. Besides fighting free radicals, it helps keep various essential biological molecules in a chemical state called reduced (as opposed to oxidized). In addition, glutathione can act on toxins such as pesticides, lead, and dry cleaning solvents, transforming them in such a way that the body can excrete them more easily.

Nutrients such as vitamin C and vitamin E
also help neutralize free radicals. In the 1990s, such antioxidant supplements
were widely promoted for preventing a variety of diseases, including cancer and
heart disease. During this period, oral glutathione became popular as an
additional antioxidant supplement. Glutathione is not absorbed when taken by
mouth, so such supplements are almost certainly useless. It may be possible,
however, to raise glutathione levels in the body by taking other supplements, such
as vitamin C, cysteine, lipoic acid, and N-acetylcysteine. Whether doing so would offer any health
benefits remains unclear.

Requirements and Sources

There is no dietary requirement for glutathione. The body makes it from scratch, utilizing vitamins and common amino acids found in food. Glutathione levels in the body are reduced by cigarette smoking. Various diseases are associated with reduced levels of glutathione, including cancer, cataracts, diabetes, and human immunodeficiency virus (HIV) infection.

Therapeutic Dosages

A typical recommended dose of oral glutathione is 50 milligrams twice daily. However, as noted above, when glutathione is taken by mouth it is destroyed. Therefore, no matter what the dose, it will not make any difference. It is possible that some glutathione may be absorbed if it is held in the mouth and allowed to dissolve, but this has not been well studied.

A more promising method for raising glutathione levels in the body involves
taking supplemental cysteine or antioxidant supplements. Evidence
suggests that cysteine (often supplied in the form of whey protein, which is high
in cysteine) can raise glutathione levels in people with cancer, hepatitis, or
HIV.

In addition, because vitamin C has overlapping functions with glutathione,
vitamin C supplements may spare some of the body’s glutathione from being used up,
thereby increasing its levels in the body. The antioxidant supplement lipoic acid
appears to raise glutathione levels as well. Other supplements that might raise
glutathione levels include N-acetylcysteine, glutamine,
methionine, and S-adenosyl methionine (SAMe).

Therapeutic Uses

Various Web sites promote glutathione for a wide variety of health problems, from preventing aging to enhancing sports performance. However, oral glutathione supplements are almost certainly useless for any condition, since they are not absorbed.

There is a bit of evidence that injected glutathione might offer a few health benefits, such as preventing blood clots during surgery, reducing the side effects and increasing the effectiveness of cancer chemotherapy drugs such as cisplatin, treating male infertility, and alleviating symptoms of early Parkinson’s disease. Although oral glutathione is not likely to provide the same benefits, it is at least theoretically possible that taking the nutrients described in the previous section (and thereby raising glutathione levels indirectly) could offer similar benefits. However, there is no direct evidence to indicate that this hypothesis is true.

Safety Issues

Oral glutathione should be entirely safe, since it is not absorbed.

Bibliography

Bharath, S., et al. “Glutathione, Iron, and Parkinson’s Disease.” Biochemical Pharmacology 64 (2002): 1037-1048.

Bounous, G. “Whey Protein Concentrate (WPC) and Glutathione Modulation in Cancer Treatment.” Anticancer Research 20 (2000): 4785-4792.

De Rosa, S. C., et al. “N-Acetylcysteine Replenishes Glutathione in HIV Infection.” European Journal of Clinical Investigation 30 (2000): 915-929.

Droge, W., and R. Breitkreutz. “Glutathione and Immune Function.” Proceedings of the Nutrition Society 59 (2000): 595-600.

Hultberg, B., et al. “Lipoic Acid Increases Glutathione Production and Enhances the Effect of Mercury in Human Cell Lines.” Toxicology 175 (2002): 103-110.

Lenzi, A., et al. “Lipoperoxidation Damage of Spermatozoa Polyunsaturated Fatty Acids (PUFA): Scavenger Mechanisms and Possible Scavenger Therapies.” Frontiers in Bioscience 5 (January, 2000): E1-E15.

Packer, L., et al. “Molecular Aspects of Lipoic Acid in the Prevention of Diabetes Complications.” Nutrition 17 (2001): 888-895.

What are some examples of transverse waves?

Waves can be classified as either longitudinal or transverse, depending upon the relative direction of medium displacement and wave propagation. If the wave propagation is perpendicular to the direction of medium displacement, the wave can be termed as transverse wave. If the direction of wave propagation is parallel to the direction of medium displacement, such waves can be termed longitudinal waves. Some examples of transverse waves include:

• Waves generated when we move a rope, tied at one end, up and down or sideways. 


• light waves


• seismic waves: S waves


• waves generated in a string


• radio waves


• microwaves


• waves generated on the surface of a liquid, when we throw a small particle in it. An example is a wave generated when we throw a stone in a pond.

Some examples of longitudinal waves include sound waves, seismic P-waves, waves in a slinky, etc.

Hope this helps. 

What is the significance of voting districts within the United States? What exactly is the function of having such a system?

We have voting districts in the United States because we think that that is the best way to make sure that the members of Congress really represent the diversity of people in our various states.  Almost every state has more than one person representing them in the House of Representatives.  All of these states are divided up into voting districts.  This means that people from relatively small geographic areas (the size depends on the state) get to elect representatives.  We feel that this is important because it gives people in each geographical area a chance to be represented in Congress.  For example, I live in Eastern Washington.  Our part of the state has very few people when compared to Western Washington. We are generally conservative while they are generally liberal.  Our senators (who are elected by the whole state) are always Democratic these days.  If we did not have voting districts, we would never have any representatives who agreed with us ideologically.  This is why we have voting districts—so that the people from various geographic areas have a better chance of being represented by people “like” them.

As for the significance of voting districts, this is a very vague question.  I suppose you could say that they are significant because they allow more people to be represented by people who are more like them ideologically.