7.7: DNA Repair
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- Ying Liu
- City College of San Francisco
Learning Objectives
By the end of this section, you will be able to do the following:
- Discuss the different types of mutations in DNA
- Explain DNA repair mechanisms
DNA replication is a highly accurate process, but mistakes can occasionally occur, such as a DNA polymerase inserting a wrong base. Uncorrected mistakes may sometimes lead to serious consequences, such as cancer. Repair mechanisms correct the mistakes. In rare cases, mistakes are not corrected, leading to mutations; in other cases, repair enzymes are themselves mutated or defective.
Most of the mistakes during DNA replication are promptly corrected by the proofreading ability of DNA polymerase itself. (Figure 14.17). In proofreading , the DNA pol reads the newly added base before adding the next one, so a correction can be made. The polymerase checks whether the newly added base has paired correctly with the base in the template strand. If it is the right base, the next nucleotide is added. If an incorrect base has been added, the enzyme makes a cut at the phosphodiester bond and releases the wrong nucleotide. This is performed by the 3' exonuclease action of DNA pol. Once the incorrect nucleotide has been removed, it can be replaced by the correct one.
Some errors are not corrected during replication, but are instead corrected after replication is completed; this type of repair is known as mismatch repair (Figure 14.18). Specific repair enzymes recognize the mispaired nucleotide and excise part of the strand that contains it; the excised region is then resynthesized. If the mismatch remains uncorrected, it may lead to more permanent damage when the mismatched DNA is replicated. How do mismatch repair enzymes recognize which of the two bases is the incorrect one? In E. coli , after replication, the nitrogenous base adenine acquires a methyl group; the parental DNA strand will have methyl groups, whereas the newly synthesized strand lacks them. Thus, DNA polymerase is able to remove the wrongly incorporated bases from the newly synthesized, non-methylated strand. In eukaryotes, the mechanism is not very well understood, but it is believed to involve recognition of unsealed nicks in the new strand, as well as a short-term continuing association of some of the replication proteins with the new daughter strand after replication has completed.
Another type of repair mechanism, nucleotide excision repair , is similar to mismatch repair, except that it is used to remove damaged bases rather than mismatched ones. The repair enzymes replace abnormal bases by making a cut on both the 3' and 5' ends of the damaged base (Figure 14.19). The segment of DNA is removed and replaced with the correctly paired nucleotides by the action of DNA pol. Once the bases are filled in, the remaining gap is sealed with a phosphodiester linkage catalyzed by DNA ligase. This repair mechanism is often employed when UV exposure causes the formation of pyrimidine dimers.
A well-studied example of mistakes not being corrected is seen in people suffering from xeroderma pigmentosa (Figure 14.20). Affected individuals have skin that is highly sensitive to UV rays from the sun. When individuals are exposed to UV light, pyrimidine dimers, especially those of thymine, are formed; people with xeroderma pigmentosa are not able to repair the damage. These are not repaired because of a defect in the nucleotide excision repair enzymes, whereas in normal individuals, the thymine dimers are excised and the defect is corrected. The thymine dimers distort the structure of the DNA double helix, and this may cause problems during DNA replication. People with xeroderma pigmentosa may have a higher risk of contracting skin cancer than those who don't have the condition.
Errors during DNA replication are not the only reason why mutations arise in DNA. Mutations , variations in the nucleotide sequence of a genome, can also occur because of damage to DNA. Such mutations may be of two types: induced or spontaneous. Induced mutations are those that result from an exposure to chemicals, UV rays, x-rays, or some other environmental agent. For example, Charlotte Auerbach and J.M Robson discovered the mutation-inducing effects of mustard gas. Spontaneous mutations occur without any exposure to any environmental agent; they are a result of natural reactions taking place within the body.
Mutations may have a wide range of effects. Point mutations are those mutations that affect a single base pair. The most common nucleotide mutations are substitutions, in which one base is replaced by another. These substitutions can be of two types, either transitions or transversions. Transition substitution refers to a purine or pyrimidine being replaced by a base of the same kind; for example, a purine such as adenine may be replaced by the purine guanine. Transversion substitution refers to a purine being replaced by a pyrimidine, or vice versa; for example, cytosine, a pyrimidine, is replaced by adenine, a purine. Some point mutations are not detectable in the final product; these are known as silent mutations. Silent mutations are usually due to a substitution in the third base of a codon, which often represents the same amino acid as the original codon. Other point mutations can result in the replacement of one amino acid by another, which may alter the function of the protein. Point mutations that generate a stop codon can terminate a protein early.
Some mutations can result in an increased number of copies of the same codon. These are called trinucleotide repeat expansions and result in repeated regions of the same amino acid. Mutations can also be the result of the addition of a base, known as an insertion, or the removal of a base, also known as deletion. If an insertion or deletion results in the alteration of the translational reading frame (a frameshift mutation), the resultant protein is usually nonfunctional. Sometimes a piece of DNA from one chromosome may get translocated to another chromosome or to another region of the same chromosome; this is also known as translocation. These mutation types are shown in Figure 14.21.
Visual Connection
Visual Connection
A frameshift mutation that results in the insertion of three nucleotides is often less deleterious than a mutation that results in the insertion of one nucleotide. Why?
Mutations in repair genes have been known to cause cancer. Many mutated repair genes have been implicated in certain forms of pancreatic cancer, colon cancer, and colorectal cancer. Mutations can affect either somatic cells or germ cells. If many mutations accumulate in a somatic cell, they may lead to problems such as the uncontrolled cell division observed in cancer. If a mutation takes place in germ cells, the mutation will be passed on to the next generation, as in the case of hemophilia and xeroderma pigmentosa.


5.9: Strain Theories
Strain theories assume people will commit crime because of strain, stress, or pressure. Depending on the version of strain theory, strain can come from a variety of origins. Strain theories also assume that human beings are naturally good; bad things happen, which “push” people into criminal activity.
[1] Moreover, the “social structure” of American society restricts some citizens from attaining it. Most, if not all, Americans know of the “American Dream.” No matter how you conceptualize the dream, most people would define the American dream as achieving economic success in some form. The culturally approved method of obtaining the American dream is through hard work, innovation, and education. However, some people and groups are not given the same opportunities to achieve the cultural goal. When there is a disjunction between the goals of a society and the appropriate means to achieve that goal, a person may feel pressure or strain. Everyone is aware of the definition and promotion of the American dream. When someone does not achieve this goal, he or she may feel strain or pressure. A person could be rejected or blocked from achieving a cultural goal. Merton claimed there were five personality adaptations between the goals of a society and the means to achieve them.
| Personality Adaptation | Cultural Goals | Institutionalized Means |
| I. Conformity | + | + |
| II. Innovation | + | – |
| III. Ritualism | – | + |
| IV. Retreatism | – | – |
| V. Rebellion | + / – | + / – |
[2] Cohen wanted to know why most juvenile crimes occurred in groups. He explained that many youths, especially those in lower class families, rejected education and other middle-class values. Instead, many teenagers would seek status and self-worth as a new value system. When teens have no status, reputation, or self-worth, it led to severe strain. To achieve status, youths commit a crime to gain status among their peer group. Cloward and Ohlin (1960) claimed more serious delinquents sought “fast cars, fancy clothes, and well dames” (p. 97). [3] Assuming youths had no legitimate opportunities to improve their economic position, youths would join gangs to pursue illegitimate opportunities to achieve financial success. Criminal gangs provided youths illicit opportunities to gain money, conflict gangs permitted youths to vent their frustrations, and retreatist gangs were double failures; they had no legitimate or illegitimate means to increase income.
[4]
Coping Mechanism Example
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Merton, R.K. (1938). Social structure and anomie
.
American Sociological Review, 3
.
↵
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Cohen, A.K. (1955).
Delinquent boys: The culture of the gang
. New York, NY: Free Press.
↵
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Cloward, R.A., & Ohlin, L. (1960).
Delinquency and opportunity: A theory of delinquent gangs
. Glencoe, IL: Free Press.
↵
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Agnew, R. (2006). Pressured into crime: An overview of general strain. New York, NY: Oxford University Press.
↵


11.4: Implement Nutritional Strategies to Impact Cardiovascular Wellness
By the end of this section, you should be able to:
- 11.3.1 Assess the client for readiness to learn.
- 11.3.2 Teach nutritional strategies to optimize cardiovascular wellness.
Holistic Nursing Assessment of the Client
An implementation strategy is necessary for success. To solidify plan compliance, the nurse should involve the client in the creation of the plan, ensure that the client has a clear comprehension of the plan, and evaluate the holistic needs of the client.
Maintaining cardiovascular health when no disease is present is also critical. A first step to maintenance is to review diet plans. The MyPlate , DASH, and Mediterranean diet s are well known and can be utilized to maintain cardiovascular health. In addition, reducing alcohol consumption, caffeine intake, red meats, saturated and trans fats, processed food consumptions, refined carbohydrates, sugary foods and drinks, and sodium have all been shown to be protective for cardiovascular health (Harvard University, 2023; Morales-Brown, 2020). Likewise, increasing the intake of fruits and vegetables, whole grains, fish, nuts, and poultry and using monounsaturated or polyunsaturated oils in place of saturated oils will help prevent cardiovascular disease (Harvard University, 2023).
If the client wishes to prescribe to one of the recommended diets, the nurse should educate them on inclusions, exclusions, and reductions (Table 11.7).
| Diet Type | Inclusions or Increases | Exclusions or Reductions |
|---|---|---|
| Mediterranean |
|
|
| DASH |
|
|
| MyPlate |
|
|
Holistic care is critical to heart health and should include a review of other lifestyle habits that can contribute to cardiovascular disease.
Physical activity is also paramount when reducing cardiovascular risks. Exercise helps with weight control, BMI, and waistline management, and reduces the risk for diabetes. Regular physical activity can also help manage stress and improve mood (Harvard University, 2023).
Lastly, sleep is a key consideration. Maintaining an adequate sleep schedule contributes to cardiovascular risk reduction. Sleep has been shown to have an impact on factors that relate to cardiovascular health, such as dietary intake, weight, exercise, inflammation, and blood pressure (Harvard University, 2023).
Client Teaching
Teaching a client with cardiovascular disease can be challenging. Symptoms like chronic fatigue, weakness, chest pain, and shortness of breath can make it difficult to motivate the client to learn. For these reasons, the nurse should include caretakers and family members whenever possible during education.
Teaching should include DASH, Mediterranean, and MyPlate diets. The nurse should help the client decide which would be most appropriate for their lifestyle. The nurse may need to adjust the diet to accommodate specific cultural and religious preferences and allergies, and to accommodate other comorbidities that require special dietary considerations.


4.6: Keyboard Interaction
Keyboard access is perhaps the most important accessibility feature that can go into a website, widget, or web application. However, it is often overlooked by developers, who are typically mouse users and may not have keyboard usability as a part of their testing regimen. People who are blind are typically unable to use a mouse, so any feature that relies on a mouse alone to function will likely be inaccessible to them. Fortunately, it is relatively easy to include keyboard access. It’s more a matter of remembering to add it when mouse access is added.
The following is a simple example of including both mouse and keyboard events when defining interaction for a widget or web application. Examine the JavaScript to see how mouse and keyboard events are handled, then under the Result tab , try operating the button with a keyboard and mouse while using ChromeVox. How you go about implementing both mouse and keyboard doesn’t really matter, as long as it is possible to interact with both.
You may notice some inconsistencies in ChromeVox support for the live region used to present the messages in the example, more specifically the
aria-atomic
attribute. Live regions will be covered more thoroughly later in this unit.
Predictability, Consistency, and Convention
Here we will introduce the basics of keyboard interaction, and we’ll go into greater detail when we start looking more closely at particular widgets and design patterns as they are introduced in the units that follow.
As the heading for this section suggests, keyboard interaction needs to be predictable, consistent, and should follow convention. That is, users should have a good idea of the path that the focus will follow (predictable). When navigating with the Tab key, that path should be the same throughout an application or website (consistent). Finally, it should be like it is in other applications, websites, or operating systems (convention).
Take for example a combo box (aka, a select menu). Regardless of the operating system being used, combo boxes work the same way. If you are developing a widget out of divs that function like a combo box, it should operate like a standard HTML combo box.
Conventional keyboard interaction for a combo box:
- Tab to navigate into the combo box
- While in focus, tab to navigate beyond the combo box
- While in focus, Shift + Tab to navigate before the combo box
- While in focus, Down Arrow to show next option
- While in focus, Up Arrow to show previous option
- While in focus, Alt + Down Arrow to display options list
- While options list is open, Alt + Up Arrow to close the options list
- While options list is open, Esc to close the options list and return to default state
- While an option is in focus, Enter to select that option
When developing a custom combobox — typically, a text box and list of options — a grid, a tree, or a dialog are combined into a functional unit that should operate like a standard HTML select menu. Functionality in addition to that described above may be added to the custom combobox, e.g., to add autocompletion . As the user types letters into the text box, options beginning with the string type are displayed below as a list or the first option with those letters is displayed inline in the text box.
Try This: Using your keyboard, try the keyboard interactions described above to confirm whether or not the combobox functions in a conventional way. Try it with a few different browsers and notice any variations in how different browsers handle combobox interaction.
Toolkit: For a list of design patterns, and keyboard interaction conventions, review the following widget development best practices. Scan for now. They will be covered more thoroughly in later units.


1.1: What is Physiology?
- Define physiology and explain its importance and connections to other fields of biological studies
Physiology is a study of how animal form or structure and function sustain life and shape responses to environmental conditions. The arctic fox (Figure 1.1), a complex animal that has adapted to its environment, illustrates the relationships between an animal’s form and function. The multicellular bodies of animals consist of tissues that make up more complex organs and organ systems. The organ systems of an animal maintain homeostasis within the multicellular body. These systems are adapted to obtain the necessary nutrients and other resources needed by the cells of the body, to remove the wastes those cells produce, to coordinate the activities of the cells, tissues, and organs throughout the body, and to coordinate the many responses of the individual organism to its environment.
Some examples of arctic fox physiological adaptions to its environment include:
- Fur with insulative properties to keep the arctic fox warm;
- Reduced heat loss through adaptations to body components such as shorter ears, legs, muzzle;
- Ability to stand on cold surfaces due to capillary rete in pads;
- Can reduce metabolic rate to conserve energy, especially helpful in times of food scarcity.
SOURCE: PESTRUD, P. (1991). Adaptations by the Arctic Fox (Alopex lagopus) to the Polar Winter. Arctic, 44 (2), 132-138. Retrieved 2018 February 5 from www.jstor.org/stable/40511073.
The study of physiology is interrelated with other fields of biological studies, such as
- Anatomy (how organisms are structured),
- Biogeography (spatial and temporal distribution of organisms),
- Biomechanics (the study of how organisms move),
- Conservation Biology (the study of the natural environment and ecosystems),
- Ecology (the study of how organisms interact with other living organisms and their environment),
- Ethology (the study of animal behaviour), and
- Other fields of Biology.
Define physiology in your own words.
Watch this video to see how Arctic foxes find prey in the winter.


14.5: Comparison with Other Planetary Systems
By the end of this section, you will be able to:
- Describe how the observations of protoplanetary disks provides evidence for the existence of other planetary systems
- Explain the two primary methods for detection of exoplanets
- Compare the main characteristics of other planetary system s with the features of the solar system
Until the middle 1990s, the practical study of the origin of planets focused on our single known example—the solar system. Although there had been a great deal of speculation about planets circling other stars, none had actually been detected. Logically enough, in the absence of data, most scientists assumed that our own system was likely to be typical. They were in for a big surprise.
Discovery of Other Planetary Systems
In The Birth of Stars and the Discovery of Planets outside the Solar System, we discuss the formation of stars and planets in some detail. Stars like our Sun are formed when dense regions in a molecular cloud (made of gas and dust) feel an extra gravitational force and begin to collapse. This is a runaway process: as the cloud collapses, the gravitational force gets stronger, concentrating material into a protostar. Roughly half of the time, the protostar will fragment or be gravitationally bound to other protostars, forming a binary or multiple star system—stars that are gravitationally bound and orbit each other. The rest of the time, the protostar collapses in isolation, as was the case for our Sun. In all cases, as we saw, conservation of angular momentum results in a spin-up of the collapsing protostar, with surrounding material flattened into a disk. Today, this kind of structure can actually be observed. The Hubble Space Telescope, as well as powerful new ground-based telescopes, enable astronomers to study directly the nearest of these circumstellar disks in regions of space where stars are being born today, such as the Orion Nebula (Figure 14.14) or the Taurus star-forming region.
Many of the circumstellar disk s we have discovered show internal structure. The disks appear to be donut-shaped, with gaps close to the star. Such gaps indicate that the gas and dust in the disk have already collapsed to form large planets (Figure 14.15). The newly born protoplanets are too small and faint to be seen directly, but the depletion of raw materials in the gaps hints at the presence of something invisible in the inner part of the circumstellar disk—and that something is almost certainly one or more planets. Theoretical models of planet formation, like the one seen at right in Figure 14.15, have long supported the idea that planets would clear gaps as they form in disks.
Our figure shows HL Tau , a one-million-year-old “newborn” star in the Taurus star-forming region. The star is embedded in a shroud of dust and gas that obscures our visible-light view of a circumstellar disk around the star. In 2014 astronomers obtained a dramatic view of the HL Tau circumstellar disk using millimeter waves, which pierce the cocoon of dust around the star, showing dust lanes being carved out by several newly formed protoplanets. As the mass of the protoplanets increases, they travel in their orbits at speeds that are faster than the dust and gas in the circumstellar disk. As the protoplanets plow through the disk, their gravitational reach begins to exceed their cross-sectional area, and they become very efficient at sweeping up material and growing until they clear a gap in the disk. The image of Figure 14.15 shows us that a number of protoplanets are forming in the disk and that they were able to form faster than our earlier ideas had suggested—all in the first million years of star formation.
For an explanation of ALMA’s ground-breaking observations of HL Tau and what they reveal about plant formation, watch this videocast from the European Southern Observatory.
Discovering Exoplanets
You might think that with the advanced telescopes and detectors astronomers have today, they could directly image planets around nearby stars (which we call exoplanets ). This has proved extremely difficult, however, not only because the exoplanets are faint, but also because they are generally lost in the brilliant glare of the star they orbit. As we discuss in more detail in The Birth of Stars and the Discovery of Planets outside the Solar System, the detection techniques that work best are indirect: they observe the effects of the planet on the star it orbits, rather than seeing the planet itself.
The first technique that yielded many planet detections is very high-resolution stellar spectroscopy. The Doppler effect lets astronomers measure the star’s radial velocity: that is, the speed of the star, toward us or away from us, relative to the observer. If there is a massive planet in orbit around the star, the gravity of the planet causes the star to wobble, changing its radial velocity by a small but detectable amount. The distance of the star does not matter, as long as it is bright enough for us to take very high quality spectra.
Measurements of the variation in the star’s radial velocity as the planet goes around the star can tell us the mass and orbital period of the planet. If there are several planets present, their effects on the radial velocity can be disentangled, so the entire planetary system can be deciphered—as long as the planets are massive enough to produce a measureable Doppler effect . This detection technique is most sensitive to large planets orbiting close to the star, since these produce the greatest wobble in their stars. It has been used on large ground-based telescopes to detect hundreds of planets, including one around Proxima Centauri, the nearest star to the Sun.
The second indirect technique is based on the slight dimming of a star when one of its planets transits , or crosses over the face of the star, as seen from Earth. Astronomers do not see the planet, but only detect its presence from careful measurements of a change in the brightness of the star over long periods of time. If the slight dips in brightness repeat at regular intervals, we can determine the orbital period of the planet. From the amount of starlight obscured, we can measure the planet’s size.
While some transits have been measured from Earth, large-scale application of this transit technique requires a telescope in space, above the atmosphere and its distortions of the star images. It has been most successfully applied from the NASA Kepler space observatory, which was built for the sole purpose of “staring” for 5 years at a single part of the sky, continuously monitoring the light from more than 150,000 stars. The primary goal of Kepler was to determine the frequency of occurrence of exoplanets of different sizes around different classes of stars. Like the Doppler technique, the transit observations favor discovery of large planets and short-period orbits. The Kepler observations closed down in 2018 when the spacecraft ran out of the fuel needed to point the telescope.
Recent detection of exoplanets using both the Doppler and transit techniques has been incredibly successful. Within two decades, we went from no knowledge of other planetary systems to a catalog of thousands of exoplanets. Most of the exoplanet s found so far are more massive than or larger in size than Earth. It is not that Earth analogs do not exist. Rather, the shortage of small rocky planets is an observational bias: smaller planets are more difficult to detect.
Analyses of the data to correct for such biases or selection effects indicate that small planets (like the terrestrial planets in our system) are actually much more common than giant planets. Also relatively common are “super Earths,” planets with two to ten times the mass of our planet (Figure 14.16). We don’t have any of these in our solar system, but nature seems to have no trouble making them elsewhere. Overall, the Kepler data suggest that approximately one quarter of stars have exoplanet systems, implying the existence of at least 50 billion planets in our Galaxy alone.
The Configurations of Other Planetary Systems
Let’s look more closely at the progress in the detection of exoplanets. Figure 14.17 shows the planets that were discovered each year by the two techniques we discussed. In the early years of exoplanet discovery, most of the planets were similar in mass to Jupiter . This is because, as mentioned above, the most massive planets were easiest to detect. In more recent years, planets smaller than Neptune and even close to the size of Earth have been detected.
We also know that many exoplanets are in multiplanet systems. This is one characteristic that our solar system shares with exosystems. Looking back at Figure 14.15 and seeing how such large disks can give rise to more than one center of condensation, it is not too surprising that multiplanet systems are a typical outcome of planet formation. Astronomers have tried to measure whether multiple planet systems all lie in the same plane using astrometry. This is a difficult measurement to make with current technology, but it is an important measurement that could help us understand the origin and evolution of planetary systems.
Comparison between Theory and Data
Many of the planetary systems discovered so far do not resemble our own solar system. Consequently, we have had to reassess some aspects of the “standard models” for the formation of planetary systems. Science sometimes works in this way, with new data contradicting our expectations. The press often talks about a scientist making experiments to “confirm” a theory. Indeed, it is comforting when new data support a hypothesis or theory and increase our confidence in an earlier result. But the most exciting and productive moments in science often come when new data don’t support existing theories, forcing scientists to rethink their position and develop new and deeper insights into the way nature works.
Nothing about the new planetary systems contradicts the basic idea that planets form from the aggregation (clumping) of material within circumstellar disks. However, the existence of “ hot Jupiter s”—planets of jovian mass that are closer to their stars than the orbit of Mercury—poses the biggest problem. As far as we know, a giant planet cannot be formed without the condensation of water ice, and water ice is not stable so close to the heat of a star. It seems likely that all the giant planets, “hot” or “normal,” formed at a distance of several astronomical units from the star, but we now see that they did not necessarily stay there. This discovery has led to a revision in our understanding of planet formation that now includes “planet migrations” within the protoplanetary disk, or later gravitational encounters between sibling planets that scatter one of the planets inward.
Many exoplanets have large orbital eccentricity (recall this means the orbits are not circular). High eccentricities were not expected for planets that form in a disk. This discovery provides further support for the scattering of planets when they interact gravitationally. When planets change each other’s motions, their orbits could become much more eccentric than the ones with which they began.
There are several suggestions for ways migration might have occurred. Most involve interactions between the giant planets and the remnant material in the circumstellar disk from which they formed. These interactions would have taken place when the system was very young, while material still remained in the disk. In such cases, the planet travels at a faster velocity than the gas and dust and feels a kind of “headwind” (or friction) that causes it to lose energy and spiral inward. It is still unclear how the spiraling planet stops before it plunges into the star. Our best guess is that this plunge into the star is the fate for many protoplanets; however, clearly some migrating planets can stop their inward motions and escape this destruction, since we find hot Jupiters in many mature planetary systems.


Describe the major concepts of humanistic theory (unconditional positive regard, the good life), as developed by Carl Rogers
Explain Maslow’s hierarchy of needs
The Humanistic Perspective: A Focus on Uniquely Human Qualities
The humanistic perspective rose to prominence in the mid-20th century in response to psychoanalytic theory and behaviorism; this perspective focuses on how healthy people develop and emphasizes an individual’s inherent drive towards self-actualization and creativity.
Humanism
emphasizes human potential and an individual’s ability to change, and rejects the idea of biological determinism. Humanistic work and research are sometimes criticized for being qualitative (not measurement-based), but there exist a number of quantitative research strains within humanistic psychology, including research on happiness, self-concept, meditation, and the outcomes of humanistic psychotherapy (Friedman, 2008).
Carl Rogers and Humanism
One pioneering humanistic theorist was Carl Rogers. He was an influential humanistic psychologist who developed a personality theory that emphasized the importance of the self-actualizing tendency in shaping human personalities. He also believed that humans are constantly reacting to stimuli with their subjective reality (
phenomenal field
), which changes continuously. Over time, a person develops a self-concept based on the feedback from this field of reality.
One of Rogers’s main ideas about personality regards self-concept, our thoughts and feelings about ourselves. How would you respond to the question, “Who am I?” Your answer can show how you see yourself.  If your response is mainly negative, then you may feel unhappy with who you are. Rogers further divided the self into two categories: the ideal self and the real self. The ideal self is the person that you would like to be; the real self is the person you actually are. Rogers focused on the idea that we need to achieve consistency between these two selves.
Unconditional Positive Regard
Human beings develop an ideal self and a real self, based on the conditional status of positive regard. How closely one’s real self matches up with their ideal self is called congruence. We experience congruence when our thoughts about our real self and ideal self are very similar—in other words when our self-concept is accurate
.
High congruence leads to a greater sense of self-worth and a healthy, productive life. Conversely, when there is a great discrepancy between our ideal and actual selves, we experience a state Rogers called incongruence, which can lead to maladjustment.
According to Rogers, parents can help their children achieve their ideal self by giving them unconditional positive regard, or unconditional love. In the development of self-concept, positive regard is key. Unconditional positive regard is an environment that is free of preconceived notions of value. Conditional positive regard is full of conditions of worth that must be achieved to be considered successful. Rogers (1980) explained it this way: “As persons are accepted and prized, they tend to develop a more caring attitude towards themselves” (p. 116).
The Good Life
Rogers described life in terms of principles rather than stages of development. These principles exist in fluid processes rather than static states. He claimed that a fully functioning person would continually aim to fulfill his or her potential in each of these processes, achieving what he called “the good life.
“
These people would allow personality and self-concept to emanate from experience. He found that fully functioning individuals had several traits or tendencies in common:
A growing openness to experience–they move away from defensiveness.
An increasingly existential lifestyle–living each moment fully, rather than distorting the moment to fit personality or self-concept.
Increasing organismic trust–they trust their own judgment and their ability to choose behavior that is appropriate for each moment.
Freedom of choice–they are not restricted by incongruence and are able to make a wide range of choices more fluently. They believe that they play a role in determining their own behavior and so feel responsible for their own behavior.
Higher levels of creativity–they will be more creative in the way they adapt to their own circumstances without feeling a need to conform.
Reliability and constructiveness–they can be trusted to act constructively. Even aggressive needs will be matched and balanced by intrinsic goodness in congruent individuals.
A rich full life–they will experience joy and pain, love and heartbreak, fear and courage more intensely.
Abraham Maslow (1908–1970) was an American psychologist who is best known for proposing a
hierarchy of human needs
in motivating behavior. Maslow described a pattern through which human motivations generally move, meaning that in order for motivation to occur at the next level, each level must be satisfied within the individual themselves. These stages include:
physiological needs: the main physical requirements for human survival, including homeostasis, food, water, sleep, shelter, and sex.
safety needs: the need for personal, emotional, financial, and physical security. Once a person’s physiological needs are relatively satisfied, their safety needs take precedence and dominate behavior. In the absence of physical safety – due to war, natural disaster, family violence, childhood abuse, institutional racism, etc. – people may (re-)experience post-traumatic stress disorder or transgenerational trauma. In the absence of economic safety – due to an economic crisis and lack of work opportunities – these safety needs manifest themselves in ways such as a preference for job security, grievance procedures for protecting the individual from unilateral authority, savings accounts, insurance policies, disability accommodations, etc. This level is more likely to predominate in children as they generally have a greater need to feel safe.
love and belonging: the need for friendships, intimacy, and belonging. This need is especially strong in childhood and it can override the need for safety as witnessed in children who cling to abusive parents. Deficiencies within this level of Maslow’s hierarchy – due to hospitalism, neglect, shunning, ostracism, etc. – can adversely affect the individual’s ability to form and maintain emotionally significant relationships in general.
esteem: the typical human desire to be accepted and valued by others. People often engage in a profession or hobby to gain recognition. Esteem needs are ego needs or status needs. People develop a concern with getting recognition, status, importance, and respect from others. Most humans have a need to feel respected; this includes the need to have self-esteem and self-respect.
self-actualization: Maslow describes this level as the desire to accomplish everything that one can, to become the most that one can be. Individuals may perceive or focus on this need very specifically. For example, one individual may have a strong desire to become an ideal parent. In another, the desire may be expressed athletically. For others, it may be expressed in paintings, pictures, or inventions. Some examples of this include utilizing abilities and talents, pursuing goals, and seeking happiness.
Furthermore, this theory is a key foundation in understanding how drive and motivation are correlated when discussing human behavior. Each of these individual levels contains a certain amount of internal sensation that must be met in order for an individual to complete their hierarchy. The goal in Maslow’s theory is to attain the fifth level or stage of
self-actualization.
Watch It
Watch as Maslow’s hierarchy of needs comes to life in this quick video.
an instance or point of agreement or correspondence between the ideal self and the real self in Rogers’ humanistic personality theory
humanism
a psychological theory that emphasizes an individual’s inherent drive towards self-actualization and contends that people have a natural capacity to make decisions about their lives and control their own behavior
Maslow’s hierarchy of needs
a motivational theory in psychology comprising a five-tier model of human needs, often depicted as hierarchical levels within a pyramid. Needs lower down in the hierarchy must be satisfied before individuals are motivated to attend to needs higher up
phenomenal field
our subjective reality, all that we are aware of, including objects and people as well as our behaviors, thoughts, images, and ideas
self-actualization
according to humanistic theory, the realizing of one’s full potential can include creative expression, a quest for spiritual enlightenment, the pursuit of knowledge, or the desire to contribute to society. For Maslow, it is a state of self-fulfillment in which people achieve their highest potential in their own unique way
Contributors and Attributions
CC licensed content, Original
The Humanistic Perspective: A focus on Uniquely Human Qualities Modification, adaptation, and original content.
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: Sonja Ann Miller for Lumen Learning.
Provided by
: Lumen Learning.
License
:
CC BY-SA: Attribution-ShareAlike


4.4: Infinite Limits. Operations in E*
As we have noted, Theorem 1 of §3 does not apply to infinite limits, even if the function values \(f(x), g(x), h(x)\) remain finite (i.e., \(i n E^{1} ) .\) Only in certain cases (stated below) can we prove some analogues.
There are quite a few such separate cases. Thus, for brevity, we shall adopt a kind of mathematical shorthand. The letter \(q\) will not necessarily denote a constant; it will stand for
\[\text{"a function } f : A \rightarrow E^{1}, A \subseteq(S, \rho),\text{ such that } f(x) \rightarrow q \in E^{1}\text{ as } x \rightarrow p.\text{"}\]
Similarly, "0" and "\(\pm\infty\)" will stand for analogous expressions, with \(q\) replaced by 0 and \(\pm \infty,\) respectively.
For example, the "shorthand formula" \((+\infty)+(+\infty)=+\infty\) means
\[\text{"The sum of two real functions, with limit}+\infty\text{ at } p\text{ } (p \in S),\text{ is itself a function with limit}+\infty\text{ at } p.\text{"}\]
The point \(p\) is fixed, possibly \(\pm \infty\left(\text {if } A \subseteq E^{*}\right).\) With this notation, we have the following theorems.
1. \((\pm \infty)+(\pm \infty)=\pm \infty\).
2. \((\pm \infty)+q=q+(\pm \infty)=\pm \infty\).
3. \((\pm \infty) \cdot(\pm \infty)=+\infty\).
4. \((\pm \infty) \cdot(\mp \infty)=-\infty\).
5. \(|\pm \infty|=+\infty\).
6. \((\pm \infty) \cdot q=q \cdot(\pm \infty)=\pm \infty\) if \(q>0\).
7. \((\pm \infty) \cdot q=q \cdot(\pm \infty)=\mp \infty\) if \(q<0\).
8. \(-(\pm \infty)=\mp \infty\).
9. \(\frac{(\pm \infty)}{q}=(\pm \infty) \cdot \frac{1}{q}\) if \(q \neq 0\).
10. \(\frac{q}{(\pm \infty)}=0\).
11. \((+\infty)^{+\infty}=+\infty\).
12. \((+\infty)^{-\infty}=0\).
13. \((+\infty)^{q}=+\infty\) if \(q>0\).
14. \((+\infty)^{q}=0\) if \(q<0\).
15. If \(q>1,\) then \(q^{+\infty}=+\infty\) and \(q^{-\infty}=0\).
16. If \(0<q<1,\) then \(q^{+\infty}=0\) and \(q^{-\infty}=+\infty\).
- Proof
-
We prove Theorems 1 and 2, leaving the rest as problems. (Theorems 11-16 are best postponed until the theory of logarithms is developed.)
1. Let \(f(x)\) and \(g(x) \rightarrow+\infty\) as \(x \rightarrow p.\) We have to show that
\[f(x)+g(x) \rightarrow+\infty,\]
i.e., that
\[\left(\forall b \in E^{1}\right)(\exists \delta>0)\left(\forall x \in A \cap G_{\neg p}(\delta)\right) \quad f(x)+g(x)>b\]
(we may assume \(b>0 ).\) Thus fix \(b>0.\) As \(f(x)\) and \(g(x) \rightarrow+\infty,\) there are \(\delta^{\prime}, \delta^{\prime \prime}>0\) such that
\[\left(\forall x \in A \cap G_{\neg p}\left(\delta^{\prime}\right)\right) f(x)>b\text{ and } \left(\forall x \in A \cap G_{\neg p}\left(\delta^{\prime \prime}\right)\right) g(x)>b.\]
Let \(\delta=\min \left(\delta^{\prime}, \delta^{\prime \prime}\right).\) Then
\[\left(\forall x \in A \cap G_{\neg p}(\delta)\right) \quad f(x)+g(x)>b+b>b,\]
as required; similarly for the case of \(-\infty\).
2. Let \(f(x) \rightarrow+\infty\) and \(g(x) \rightarrow q \in E^{1}.\) Then there is \(\delta^{\prime}>0\) such that for \(x\) in \(A \cap G_{\neg p}\left(\delta^{\prime}\right),|q-g(x)|<1,\) so that \(g(x)>q-1\).
Also, given any \(b \in E^{1},\) there is \(\delta^{\prime \prime}\) such that
\[\left(\forall x \in A \cap G_{-p}\left(\delta^{\prime \prime}\right)\right) \quad f(x)>b-q+1.\]
Let \(\delta=\min \left(\delta^{\prime}, \delta^{\prime \prime}\right).\) Then
\[\left(\forall x \in A \cap G_{\neg p}(\delta)\right) \quad f(x)+g(x)>(b-q+1)+(q-1)=b,\]
as required; similarly for the case of \(f(x) \rightarrow-\infty\).
Caution: No theorems of this kind exist for the following cases (which therefore are called indeterminate expressions ):
\[(+\infty)+(-\infty), \quad( \pm \infty) \cdot 0, \quad \frac{ \pm \infty}{ \pm \infty}, \quad \frac{0}{0}, \quad( \pm \infty)^{0}, \quad 0^{0}, \quad 1^{ \pm \infty}.\]
In these cases, it does not suffice to know only the limits of \(f\) and \(g.\) It is necessary to investigate the functions themselves to give a definite answer, since in each case the answer may be different, depending on the properties of \(f\) and \(g.\) The expressions (1*) remain indeterminate even if we consider the simplest kind of functions, namely sequences, as we show next.
(a) Let
\[u_{m}=2 m\text{ and } v_{m}=-m.\]
(This corresponds to \(f(x)=2 x\) and \(g(x)=-x.)\) Then, as is readily seen,
\[u_{m} \rightarrow+\infty, v_{m} \rightarrow-\infty,\text{ and } u_{m}+v_{m}=2 m-m=m \rightarrow+\infty.\]
If, however, we take \(x_{m}=2 m\) and \(y_{m}=-2 m,\) then
\[x_{m}+y_{m}=2 m-2 m=0;\]
thus \(x_{m}+y_{m}\) is constant, with limit 0 (for the limit of a constant function equals its value; see §1, Example (a)).
Next, let
\[u_{m}=2 m\text{ and } z_{m}=-2 m+(-1)^{m}.\]
Then again
\[u_{m} \rightarrow+\infty\text{ and } z_{m} \rightarrow-\infty,\text{ but } u_{m}+z_{m}=(-1)^{m};\]
\(u_{m}+z_{m}\) "oscillates" from \(-1\) to 1 as \(m \rightarrow+\infty,\) so it has no limit at all.
These examples show that \((+\infty)+(-\infty)\) is indeed an indeterminate expression since the answer depends on the nature of the functions involved. No general answer is possible.
(b) We now show that \(1^{+\infty}\) is indeterminate.
Take first a constant \(\left\{x_{m}\right\}, x_{m}=1,\) and let \(y_{m}=m.\) Then
\[x_{m} \rightarrow 1, y_{m} \rightarrow+\infty,\text{ and } x_{m}^{y_{m}}=1^{m}=1=x_{m} \rightarrow 1.\]
If, however, \(x_{m}=1+\frac{1}{m}\) and \(y_{m}=m,\) then again \(y_{m} \rightarrow+\infty\) and \(x_{m} \rightarrow 1\) (by Theorem 10 above and Theorem 1 of Chapter 3, §15), but
\[x_{m}^{y_{m}}=\left(1+\frac{1}{m}\right)^{m}\]
does not tend to \(1 ;\) it tends to \(e>2,\) as shown in Chapter 3, §15. Thus again the result depends on \(\left\{x_{m}\right\}\) and \(\left\{y_{m}\right\}.\)
In a similar manner, one shows that the other cases (1*) are indeterminate.
Note 1. It is often useful to introduce additional "shorthand" conventions. Thus the symbol \(\infty\) (unsigned infinity) might denote a function\(f\) such that
\[|f(x)| \rightarrow+\infty\text{ as } x \rightarrow p;\]
we then also write \(f(x) \rightarrow \infty.\) The symbol \(0^{+}\) (respectively, \(0^{-})\) denotes a function \(f\) such that
\[f(x) \rightarrow 0\text{ as } x \rightarrow p\]
and, moreover
\[f(x)>0\text{ } (f(x)<0,\text { respectively})\text{ on some } G_{\neg p}(\delta).\]
We then have the following additional formulas:
(i) \(\frac{( \pm \infty)}{0^{+}}=\pm \infty, \frac{( \pm \infty)}{0^{-}}=\mp \infty\).
(ii) If \(q>0,\) then \(\frac{q}{0^{+}}=+\infty\) and \(\frac{q}{0^{-}}=-\infty\).
(iii) \(\frac{\infty}{0}=\infty\).
(iv) \(\frac{q}{\infty}=0\).
The proof is left to the reader.
Note 2. All these formulas and theorems hold for relative limits, too.
So far, we have defined no arithmetic operations in \(E^{*}.\) To fill this gap (at least partially), we shall henceforth treat Theorems 1-16 above not only as certain limit statements (in "shorthand") but also as definitions of certain operations in \(E^{*}.\) For example, the formula \((+\infty)+(+\infty)=+\infty\) shall be treated as the definition of the actual sum of \(+\infty\) and \(+\infty\) in \(E^{*},\) with \(+\infty\) regarded this time as an element of \(E^{*}\) (not as a function). This convention defines the arithmetic operations for certain cases only; the indeterminate expressions (1*) remain undefined, unless we decide to assign them some meaning.
In higher analysis, it indeed proves convenient to assign a meaning to at least some of them. We shall adopt these (admittedly arbitrary) conventions:
\(\left\{\begin{array}{l}{( \pm \infty)+(\mp \infty)=( \pm \infty)-( \pm \infty)=+\infty ; 0^{0}=1;} \\ {0 \cdot( \pm \infty)=( \pm \infty) \cdot 0=0 \text { (even if } 0 \text { stands for the zero-vector } ).}\end{array}\right.\)
Caution: These formulas must not be treated as limit theorems (in "short-hand"). Sums and products of the form (2*) will be called " unorthodox ."


<IP_ADDRESS>: Allopatric Speciation
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Learning Objectives
- Give examples of allopatric speciation
Allopatric Speciation
A geographically-continuous population has a gene pool that is relatively homogeneous. Gene flow, the movement of alleles across the range of the species, is relatively free because individuals can move and then mate with individuals in their new location. Thus, the frequency of an allele at one end of a distribution will be similar to the frequency of the allele at the other end. When populations become geographically discontinuous, that free-flow of alleles is prevented. When that separation continues for a period of time, the two populations are able to evolve along different trajectories. This is known as allopatric speciation. Thus, their allele frequencies at numerous genetic loci gradually become more and more different as new alleles independently arise by mutation in each population. Typically, environmental conditions, such as climate, resources, predators, and competitors for the two populations will differ causing natural selection to favor divergent adaptations in each group.
Isolation of populations leading to allopatric speciation can occur in a variety of ways: a river forming a new branch, erosion forming a new valley, a group of organisms traveling to a new location without the ability to return, or seeds floating over the ocean to an island. The nature of the geographic separation necessary to isolate populations depends entirely on the biology of the organism and its potential for dispersal. If two flying insect populations took up residence in separate nearby valleys, chances are individuals from each population would fly back and forth, continuing gene flow. However, if two rodent populations became divided by the formation of a new lake, continued gene flow would be improbable; therefore, speciation would be probably occur.
Biologists group allopatric processes into two categories: dispersal and vicariance. Dispersal occurs when a few members of a species move to a new geographical area, while vicariance occurs when a natural situation arises to physically divide organisms.
Scientists have documented numerous cases of allopatric speciation. For example, along the west coast of the United States, two separate sub-species of spotted owls exist. The northern spotted owl has genetic and phenotypic differences from its close relative, the Mexican spotted owl, which lives in the south.
Additionally, scientists have found that the further the distance between two groups that once were the same species, the more probable it is that speciation will occur. This seems logical because as the distance increases, the various environmental factors would generally have less in common than locations in close proximity. Consider the two owls: in the north, the climate is cooler than in the south causing the types of organisms in each ecosystem differ, as do their behaviors and habits. Also, the hunting habits and prey choices of the southern owls vary from the northern owls. These variances can lead to evolved differences in the owls, resulting in speciation.
Adaptive Radiation
In some cases, a population of one species disperses throughout an area with each finding a distinct niche or isolated habitat. Over time, the varied demands of their new lifestyles lead to multiple speciation events originating from a single species. This is called adaptive radiation because many adaptations evolve from a single point of origin, causing the species to radiate into several new ones. Island archipelagos like the Hawaiian Islands provide an ideal context for adaptive radiation events because water surrounds each island which leads to geographical isolation for many organisms. The Hawaiian honeycreeper illustrates one example of adaptive radiation. From a single species, called the founder species, numerous species have evolved.
In Hawaiian honeycreepers, the response to natural selection based on specific food sources in each new habitat led to the evolution of a different beak suited to the specific food source. The seed-eating birds have a thicker, stronger beak which is suited to break hard nuts. The nectar-eating birds have long beaks to dip into flowers to reach the nectar. The insect-eating birds have beaks like swords, appropriate for stabbing and impaling insects.
Key Points
- When a population is geographically continuous, the allele frequencies among its members are similar; however, when a population becomes separated, the allele frequencies between the two groups can begin to vary.
- If the separation between groups continues for a long period of time, the differences between their alleles can become more and more pronounced due to differences in climate, predation, food sources, and other factors, eventually leading to the formation of a new species.
- Geographic separation between populations can occur in many ways; the severity of the separation depends on the travel capabilities of the species.
- Allopatric speciation events can occur either by dispersal, when a few members of a species move to a new geographical area, or by vicariance, when a natural situation, such as the formation of a river or valley, physically divide organisms.
- When a population disperses throughout an area, into new, different and often isolated habitats, multiple speciation events can occur in which the single original species gives rise to many new species; this phenomenon is called adaptive radiation.
Key Terms
- vicariance : the separation of a group of organisms by a geographic barrier, resulting in differentiation of the original group into new varieties or species
- adaptive radiation : the diversification of species into separate forms that each adapt to occupy a specific environmental niche
- dispersal : the movement of a few members of a species to a new geographical area, resulting in differentiation of the original group into new varieties or species


3.1: Description and Objectives
Description
A number of different networking and SCADA protocols, hardware, and security devices are available to protect a network and the devices on that network. This module addresses the various mechanisms for employing hardware, protocols, and technologies with basic protections in infrastructure and network design. It also identifies methods for enhancing the security of an enterprise network through the positioning of certain pieces of hardware, protocol, and network equipment.
Objectives
- List several types of networking hardware and explain the purpose of each.
- List and describe the functions of common communications protocols and network standards used within CI.
- Identify new types of network applications and how they can be secured.
- Identify and understand the differences between IPv4 and IPv6.
- Discuss the unique challenges/characteristics of devices associated with industrial control systems.
- Explain how existing network administration principles can be applied to secure CIKR.


18.1: Introduction to Gothic Art
Gothic Art
Gothic art developed after the Romanesque, in the 12 th century. The style continued to be used well into the 16 th century in some parts of Europe, while giving way to the Renaissance style earlier in some regions.
Learning Objective
Describe the economic and political reasons that led to the development of the Gothic style
Key Points
- An increased population of cities in France, as well as a strengthened French monarch, contributes to the development of the Gothic style.
- The most expressive medium for the Gothic style is architecture, specifically, Cathedrals.
- While the Gothic style was developed in Northern France, it spread throughout Europe where different regional styles were adopted.
Key Term
- Book of Hours : A common type of illuminated manuscript that was created for personal devotion and contained a collection of texts, prayers, and psalms.
Gothic art developed after the Romanesque, in the 12 th century. The style continued to be used well into the 16 th century in some parts of Europe, while giving way to the Renaissance style earlier in other regions. The style was developed in Northern France due to socioeconomic, political, and theological reasons.
After the fall of the Roman Empire, people fled cities as they were no longer safe. The Romanesque era saw many people living in the countryside of France while cities remained largely abandoned. During this time period, the French monarchy was weak and feudal landowners exerted a large amount of
regional power. In the 12
th
century, the French royalty strengthened their power, their titles, and their landholdings, which led to more centralized government. Additionally, due to advancements in
agriculture, population and trade increased. These changes brought people back to the cities, which is where we find the most expressive medium for the Gothic style—cathedrals.
Gothic Architecture
Gothic architecture is unique in that we can pinpoint the exact place, the exact moment, and the exact person who developed it. Around 1137, Abbot Suger began re-building the Abbey Church of St. Denis. In his re-designs, which he wrote about extensively, we can see elements of what would become Gothic architecture, including the use of symmetry in design and ratios.
Ratios became essential to French Gothic cathedrals because they expressed the perfection of the universe created by God. This is where we also see stained glass emerge in Gothic architecture. Abbot Suger adopted the idea that light equates to God. He wrote that he placed pictures in the glass to replace wall paintings and talked about them as educational devices. The windows were instructional in theology during the Gothic era, and the light itself was a metaphor for the presence of God.
Cathedrals served as religious centers and they were important for local economies. Pilgrims would travel throughout Europe to see relics, which would bring an influx of travelers and money to cities with Cathedrals.
While the Gothic style was developed in Northern France, it spread throughout Europe where different regional styles were adopted. In England, for example, cathedrals became longer than they were tall and architects in Italy typically did not incorporate stained glass windows in the manner that the French did.
Gothic Painting
Illuminated manuscripts provide excellent examples of Gothic painting. A prayer book, known as the book of hours, became increasingly popular during the Gothic age and was treated as a luxury item. The Hours of Mary of Burgundy, produced in Flanders c. 1477, contains a miniature showing Mary of Burgundy in devotion with a wonderful depiction of a French Gothic Cathedral behind her.
Sculpture & Metalwork
Sculpture during the Gothic era really sheds light on the knowledge of artists working during this time period. Some historians believed that artists and artisans during the Gothic era had “forgotten” how to create realistic works of art, or art influenced by the classical age. However, a viewer only needs to look at the work of Nicolas of Verdun to see that artists could and did work in a classical style during the Gothic era. Additionally, sculpture produced in Germany during the Gothic era is especially noted for its lifelikeness.
Gothic Cathedrals
French Gothic cathedrals are characterized by lighter construction, large windows, pointed arches, and their impressive height.
Learning Objective
Evaluate the structure and symbolism of the French Gothic cathedral
Key Points
- French Gothic cathedrals were characterized by lighter construction and large windows.
- The pointed arch was the defining architectural feature of Gothic construction.
- Height is enhanced by both the architectural features and the decoration of the building.
- All design elements of Gothic cathedrals are intended to pay homage to and bring attention to the Glory of God.
- The western entrance to the Cathedral is typically the primary point of entry and therefore the most elaborate facade.
- Stained glass adds a dimension of color to the light within the building, as well as providing a medium for figurative and narrative art.
Key Terms
- Ogival : Having the curved, pointed shape of a Gothic pointed arch, or a rib of a Gothic vault.
- Lancet Arch : A sharp pointed arch used in doors and windows, etc.
- Gothic Architecture : A style of architecture that flourished during the high and late medieval period; it evolved from Romanesque architecture and was succeeded by Renaissance architecture.
- Jamb : The vertical components that form the sides of a door frame, window frame, or fireplace, or other opening in a wall.
- Blind Arcade : A series of arches, often used in Romanesque and Gothic buildings, that has no actual openings and has no load-bearing function, and that is applied to the surface of a wall as a decorative element.
- Nave : The middle or body of a church, extending from the transepts to the principal entrances.
The Gothic cathedral represented the universe in microcosm, and each architectural concept, including the height and perfect ratios of the structure, were intended to convey a theological message: the great glory of God and his creation of a perfect universe. The building becomes a microcosm in two ways. First, the mathematical and geometrical nature of the construction is an image of the orderly universe, in which an underlying rationality and logic can be perceived. Second, the statues, sculptural decoration, stained glass, and murals incorporate the essence of creation in depictions of events from the Old and New Testaments.
Most Gothic churches have the Latin cross (or “cruciform”) plan, with a long nave making the body of the church. This nave is flanked on either side by aisles, a transverse arm called the transept, and, beyond it, an extension referred to as the choir.
One of the defining characteristics of Gothic architecture is the pointed or ogival arch. Arches of this type were used in the Near East in pre-Islamic as well as Islamic architecture before they were structurally employed in Gothic architecture. They are thought to have been the inspiration for their use in France at the Autun Cathedral, which is otherwise stylistically Romanesque. The way in which the pointed arch was drafted and utilized developed throughout the Gothic period, and four popular styles emerged: the Lancet arch, the Equilateral arch, the Flamboyant arch, and the Depressed arch.
The Gothic vault, unlike the semi-circular vault of Roman and Romanesque buildings, can be used to roof rectangular and irregularly shaped plans such as trapezoids. This enabled architects to raise vaults much higher than was possible in Romanesque architecture. While the use of the pointed arch gave a greater flexibility to architectural form, it also gave Gothic architecture a very different and more vertical visual characteristic than Romanesque architecture.
In Gothic architecture the pointed arch is used in every location where a vaulted shape is called for, both structurally and decoratively. Gothic openings such as doorways, windows, arcades, and galleries have pointed arches. Rows of pointed arches upon delicate shafts form a typical wall decoration known as a blind arcade. Niches with pointed arches that contain statuary are a major external feature. The pointed arch lent itself to elaborate intersecting shapes, which developed complex Gothic tracery within window spaces and formed the structural support of the large windows that are characteristic of the style.
The façade of a large church or cathedral, often referred to as the West Front, is generally designed to create a powerful impression on the approaching worshiper. In the arch of the door (the tympanum) is often a significant sculpture representing scenes from Christian Theology, most frequently Christ in Majesty and Judgment Day . If there is a central door jamb or a tremeau, then it frequently bears a statue of the Madonna and Child.
The West Front of a French cathedral, along with many English, Spanish, and German cathedrals, generally has two towers, which, particularly in France, express an enormous diversity of form and decoration. A characteristic of French Gothic church architecture is its height, both absolute and in proportion to its width, the verticality suggests an aspiration to Heaven. As the Gothic Age progressed in France, the different towns and cities may have been in competition with one another to create the tallest Cathedral. Architects also closely guarded the ratios they used in their architectural plans.
Another one of the most distinctive characteristics of Gothic architecture is the expansive area of windows and the large size of the many individual windows. The increase in the use of large windows during the Gothic period is directly related to the use of the pointed arch, the ribbed vault, and the flying buttress. All of these architectural features absorbed the weight of the structure, which had rested on the walls in Romanesque architecture. Since the walls had less weight to support, thanks to these innovations, architects were able to pierce the walls of the structures with windows without risking the structural soundness of the cathedral.
- Curation and Revision. Provided by : Boundless.com. License : CC BY-SA: Attribution-ShareAlike
- Shrine of the Three Kings. Provided by : Wikipedia. Located at : https://en.Wikipedia.org/wiki/Shrine_of_the_Three_Kings . License : CC BY-SA: Attribution-ShareAlike
- Book of Hours. Provided by : Wikipedia. Located at : https://en.Wikipedia.org/wiki/Book_of_hours . License : CC BY-SA: Attribution-ShareAlike
- Gothic Art. Provided by : Wikipedia. Located at : https://en.Wikipedia.org/wiki/Gothic_art . License : CC BY-SA: Attribution-ShareAlike
- The Hours of Mary of Burgundy. Provided by : Wikipedia. Located at : https://en.Wikipedia.org/wiki/Hours_of_Mary_of_Burgundy . License : CC BY-SA: Attribution-ShareAlike
- StDenis_Chorumgang.JPG. Provided by : Wikipedia. Located at : https://en.Wikipedia.org/wiki/Suger . License : CC BY-SA: Attribution-ShareAlike
- Stundenbuch_der_Maria_von_Burgund_Wien_cod._1857_14v.jpg. Provided by : Wikipedia. Located at : https://en.Wikipedia.org/wiki/Hours_of_Mary_of_Burgundy . License : Public Domain: No Known Copyright
- Cologne_Cathedral_Shrine_of_Magi.jpg. Provided by : Wikipedia. Located at : https://en.Wikipedia.org/wiki/Nicholas_of_Verdun . License : CC BY-SA: Attribution-ShareAlike
- blind arcade. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/blind%20arcade. License : CC BY-SA: Attribution-ShareAlike
- Gothic Architecture. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/gothic%20architecture. License : CC BY-SA: Attribution-ShareAlike
- jamb. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/jamb. License : CC BY-SA: Attribution-ShareAlike
- nave. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/nave. License : CC BY-SA: Attribution-ShareAlike
- lancet arch. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/lancet_arch. License : CC BY-SA: Attribution-ShareAlike
- Autun cathedrale. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Autun_cathedrale.jpg. License : CC BY: Attribution
- Bonne-Esperance Salle capitulaire. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Bonne-Esperance_Salle_capitulaire.JPG. License : CC BY: Attribution
- Koelner Dom Innenraum. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:Koelner_Dom_Innenraum.jpg. License : CC BY: Attribution


There are a number of attempts to explain why we age and many factors that contribute to aging. The
peripheral slowing hypothesis
suggests that overall processing speed declines in the peripheral nervous system, affecting the brain’s ability to communicate with muscles and organs. Some of the peripheral nervous system (PNS) is under a person’s voluntary control, such as the nerves carrying instructions from the brain to the limbs. As well as controlling muscles and joints, the PNS sends all the information from the senses back to the brain.
The
generalized slowing hypothesis
theory suggests that processing in all parts of the nervous system, including the brain, are less efficient with age. This may be why older people have more accidents. Genetics, diet, lifestyle, activity, and exposure to pollutants all play a role in the aging process.
[1]
[2]
[3]
Cell Life
Cells divide a limited number of times
and then stop. This phenomenon, known as the
Hayflick limit
, is evidenced in cells studied in test tubes which divide about 50 times before becoming senescent. In 1961, Dr. Hayflick theorized that the human cell’s ability to divide is limited to approximately 50-times, after which they simply stop dividing (the Hayflick limit theory of aging). According to telomere theory, telomeres have experimentally been shown to shorten with each successive cell division.
[4]
Senescent cells do not die. They simply stop replicating. Senescent cells can help limit the growth of other cells which may reduce risk of developing tumors when younger, but can alter genes later in life and result in promoting the growth of tumors as we age (Dollemore, 2006). Limited cell growth is attributed to telomeres which are the tips of the protective coating around chromosomes. Each time cells replicate, the telomere is shortened. Eventually, loss of telomere length is thought to create damage to chromosomes and produce cell senescence.
Link to Learning
Watch this Ted talk by molecular biologist Elizabeth Blackburn on “
The Science of Cells That Never Get Old
.” Blackburn won a Nobel Prize for her pioneering work on telomeres and telomerase, which may play central roles in how we age.
Biochemistry and Aging
Free Radical Theory of Aging
The
free radical
theory of aging
(
FRTA
) states that organisms age because cells accumulate free radical damage over time. A free radical is any atom or moleculewhich has a single unpaired electron in an outer shell. This means that as oxygen is metabolized, mitochondria in the cells convert the oxygen to adenosine triphosphate (ATP) which provides energy to the cell. Unpaired electrons are a byproduct of this process and these unstable electrons cause cellular damage as they find other electrons with which to bond. These free radicals have some benefits and are used by the immune system to destroy bacteria. However, cellular damage accumulates and eventually reduces functioning of organs and systems. Many food products and vitamin supplements are promoted as age-reducing. Antioxidant drugs have been shown to increase the longevity in nematodes (small worms), but the ability to slow the aging process by introducing antioxidants in the diet is still controversial.
Protein Crosslinking
This theory focuses on the role blood sugar, or glucose, plays in the aging of cells. Glucose molecules attach themselves to proteins and form chains or crosslinks. These crosslinks reduce the flexibility of tissue and thus it becomes stiff and loses functioning. The circulatory system becomes less efficient as the tissue of the heart, arteries and lungs lose flexibility. Joints grow stiff as glucose combines with collegen.
DNA Damage
Through the normal growth and aging process, DNA is damaged by environmental factors such as toxic agents, pollutants, and sun exposure (Dollemore, 2006). This results in deletions of genetic material, and mutations in the DNA duplicated in new cells. The accumulation of these errors results in reduced functioning in cells and tissues. Theories that suggest that the body’s DNA genetic code contains a bui .epub/13:_Module_10:_Late_Adulthood/13.7:_Theories_on_Aging#footnote-386-5" class="footnote">
[5]
Decline in the Immune System
As we age, B-lymphocytes and T-lymphocytes become less active. These cells are crucial to the immune system as they secrete antibodies and directly attack infected cells. The thymus, where T-cells are manufactured, shrinks as aging progresses. This reduces our body’s ability to fight infection (Berger, 2005).
theory that organisms age because cells accumulate free radical damage over time
generalized slowing hypothesis
the theory that processing in all parts of the nervous system, including the brain, is less efficient
Hayflick limit
the number of times a normal human cell population will divide before cell division stops
peripheral slowing hypothesis
the theory that overall processing speed declines with age in the peripheral nervous system
Plude, D. J., & Doussard-Roosevelt, J. A. (1989).
Aging, selective attention, and feature integration. Psychology and Aging, 4(1), 98-105.
<EMAIL_ADDRESS>NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health. Murray MM, Wallace MT, editors
<EMAIL_ADDRESS>The Neural Bases of Multisensory Processes. Boca Raton (FL): CRC Press/Taylor & Francis; 2012. Chapter 20Multisensory Integration and Aging Authors Jennifer L. Mozolic, Christina E. Hugenschmidt, Ann M. Peiffer, and Paul J. Laurienti.
<EMAIL_ADDRESS>Kunlin, Jin. (2010). Modern Biological Theories Of Aging. Aging Dis. 2010 Oct; 1(2): 72–74. Published online 2010 Aug 1. PMCID: PMC2995895 NIHMSID: NIHMS248183 PMID: 21132086.
<EMAIL_ADDRESS>Contributors and Attributions
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1.2: Algebra Support Last updated Save as PDF Page ID 128477 Katherine Skelton Highline College 1.2.1: Real Numbers, Linear Inequalities, and Interval Notation 1.2.2: Basics of the Graphing Calculator 1.2.3: Polynomial Expressions 1.2.4: Adding and Subtracting Polynomial Expressions 1.2.5: Properties of Exponents 1.2.6: Multiplying Polynomial Expressions 1.2.7: The Greatest Common Factor and Factor by Grouping 1.2.8: Solving Polynomial Equations 1.2.9: Factoring ax² + bx + c when a =1 1.2.10: Factoring ax² + bx + c when a≠1 1.2.11: Factoring Special Products 1.2.12: General Strategy for Factoring Polynomials 1.2.13: Simplifying, Multiplying, and Dividing Rational Expressions 1.2.14: Adding and Subtracting Rational Expressions 1.2.15: Simplifying Complex Rational Expressions 1.2.16: Solving Rational Equations 1.2.17: Simplifying Expressions with Roots 1.2.18: Simplifying Radical Expressions 1.2.19: Simplifying Rational Exponents 1.2.20: Adding, Subtracting, and Multiplying Radical Expressions 1.2.21: Dividing Radical Expressions 1.2.22: Solving Radical Equations 1.2.23: Complex Numbers 1.2.24: Solving Quadratic Equations Using the Square Root Property 1.2.25: Solving Quadratic Equations by Completing the Square 1.2.26: Solving Quadratic Equations Using the Quadratic Formula 1.2.27: Solving Equations in Quadratic Form 1.2.EA: Exercises for Polynomials Expressions 1.2.EB: Exercises for Factoring Polynomial Expressions and Solving Polynomial Equations 1.2.EC: Exercises for Rational Expressions and Equations 1.2.ED: Exercises for Radical Expressions and Equations 1.2.EE: Exercises for Quadratic Equations


12.7: Additional Resources
StatTutor
The following StatTutor interactive scenarios appear through out the course; they are listed here for easy access.
| StatTutor Interactives | |
|---|---|
| Activity | Module |
| StatTutor: Drinking Habits of College Students | Module 2: Summarizing Data Graphically and Numerically |
| StatTutor: Academic Performance | Module 3: Examining Relationships: Quantitative Data |
| StatTutor: Treating Depression: A Randomized Clinical Trial | Module 5: Relationships in Categorical Data with Intro to Probability |
| StatTutor: Cell Phones | Module 8: Inference for One Proportion |
| StatTutor: Analyzing Data From a Course’s Grade Book | Module 10: Inference for Means |
| StatTutor: Risk Factors for Low Birth Weight | Module 11: Chi-Square Tests |
Below are direct links to the StatTutor labs on Lumen’s server. These links are provided to instructors who want to be able to pull up an instance of StatTutor in class that doesn’t have their previous progress saved (e.g. in order to be able to demo a StatTutor Lab to a class from its initial state).
These links should not be given to students, as work that students would do here is not connected to Waymaker, and thus their progress would not be saved. Students should access the StatTutor labs directly from Waymaker so that if they go back to a given StatTutor lab, they are able to see their previous progress and continue working through the lab from that point.
| Activity | Module |
|---|---|
| Drinking Habits of College Students | Module 2: Summarizing Data Graphically and Numerically |
| Body Image and Academic Performance | Module 3: Examining Relationships: Quantitative Data |
| Treating Depression: A Randomized Clinical Trial | Module 5: Relationships in Categorical Data with Intro to Probability |
| Cell Phones | Module 8: Inference for One Proportion |
| Analyzing Data From a Course’s Grade Book | Module 10: Inference for Means |
| Risk Factors for Low Birth Weight | Module 11: Chi-Square Tests |
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- Additional Resources. Provided by : Lumen Learning. License : CC BY: Attribution
- Folder Arrow. Authored by : AlfredoCreates.com. Provided by : Noun Project. Located at : https://thenounproject.com/term/folder-arrow/444206/ . License : CC BY: Attribution


16.9: Benzyne
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Objectives
After completing this section, you should be able to
- identify the reagents and conditions required to produce phenol from chlorobenzene on an industrial scale.
- write the mechanism for the conversion of an alkyl halide to a phenol through a benzyne intermediate.
- discuss the experimental evidence which supports the existence of benzyne intermediates.
- discuss the bonding in benzyne, and hence account for its high reactivity.
Key Terms
Make certain that you can define, and use in context, the key terms below.
- benzyne
- elimination-addition mechanism
Study Notes
An elimination-addition mechanism involves the elimination of the elements of a small molecule from a substrate to produce a highly reactive intermediate, which then undergoes an addition reaction.
The elimination-addition mechanism of nucleophilic aromatic substitution involves the remarkable intermediate called benzyne or arynes.
Elimination-Addition Mechanism of Nucleophilic Aromatic Substitution. Arynes
The reactivities of aryl halides, such as the halobenzenes, are exceedingly low toward nucleophilic reagents that normally effect substitution with alkyl halides and activated aryl halides. Substitutions do occur under forcing conditions of either high temperatures or very strong bases. For example, chlorobenzene reacts with sodium hydroxide solution at temperatures around \(340^\text{o}\) and this reaction was once an important commercial process for the production of benzenol (phenol):
In addition, aryl chlorides, bromides, and iodides can be converted to areneamines \(\ce{ArNH_2}\) by the conjugate bases of amines. In fact, the reaction of potassium amide with bromobenzene is extremely rapid, even at temperatures as low as \(-33^\text{o}\) with liquid ammonia as solvent:
However, substitution reactions of this type differ from the previously discussed substitutions of activated aryl halides in that rearrangement often occurs. That is, the entering group does not always occupy the same position on the ring as that vacated by the halogen substituent . For example, the hydrolysis of 4-chloromethylbenzene at \(340^\text{o}\) gives an equimolar mixture of 3- and 4-methylbenzenols:
Even more striking is the exclusive formation of 3-methoxybenzenamine in the amination of 2-chloromethoxybenzene. Notice that this result is a violation of the principle of least structural change:
The mechanism of this type of reaction has been studied extensively, and much evidence has accumulated in support of a stepwise process, which proceeds first by base-catalyzed elimination of hydrogen halide \(\left( \ce{HX} \right)\) from the aryl halide - as illustrated below for the amination of bromobenzene:
Elimination
The product of the elimination reaction is a highly reactive intermediate \(9\) called benzyne , or dehydrobenzene , which differs from benzene in having two less hydrogen and an extra bond between two ortho carbons. Benzyne reacts rapidly with any available nucleophile, in this case the solvent, ammonia, to give an addition product:
Addition
The rearrangements in these reactions result from the attack of the nucleophile at one or the other of the carbons of the extra bond in the intermediate. With benzyne the symmetry is such that no rearrangement would be detected. With substituted benzynes isomeric products may result. Thus 4-methylbenzyne, \(10\), from the reaction of hydroxide ion with 4-chloro-1-methylbenzene gives both 3- and 4-methylbenzenols:
In the foregoing benzyne reactions the base that produces the benzyne in the elimination step is derived from the nucleophile that adds in the addition step. This need not always be so, depending on the reaction conditions. In fact, the synthetic utility of aryne reactions depends in large part of the success with which the aryne can be generated by one reagent but captured by another. One such method will be discussed in Section 14-10C and involves organometallic compounds derived from aryl halides. Another method is to generate the aryne by thermal decomposition of a 1,2-disubstituted arene compound such as \(11\), in which both substituents are leaving groups - one leaving with an electron pair, the other leaving without:
When \(11\) decomposes in the presence of an added nucleophile, the benzyne intermediate is trapped by the nucleophile as it is formed. Or, if a conjugated diene is present, benzyne will react with it by a [4 + 2] cycloaddition. In the absence of other compounds with which it can react, benzyne will undergo [2 + 2] cycloaddition to itself:
Exercise \(\PageIndex{1}\)
When p -chlorotoluene is reacted with NaOH, two products are seen. While when m -chlorotoluene is reacted with NaOH, three products are seen. Explain this.
- Answer
-
You need to look at the benzyne intermediates. The para substituted only allows for two products, while the para produces two different alkynes which give three different products.


5.7: Reading- Name Server
Introduction
A name server is a computer hardware or software server that implements a network service for providing responses to queries against a directory service. It translates an often humanly meaningful, text-based identifier to a system-internal, often numeric identification or addressing component. This service is performed by the server in response to a service protocol request.
An example of a name server is the server component of the Domain Name System (DNS), one of the two principal name spaces of the Internet. The most important function of DNS servers is the translation (resolution) of human-memorable domain names and hostnames into the corresponding numeric Internet Protocol (IP) addresses, the second principal name space of the Internet which is used to identify and locate computer systems and resources on the Internet.
Domain Name System
The Internet maintains two principal namespaces: the domain name hierarchy and the IP address system. The Domain Name System maintains the domain namespace and provides translation services between these two namespaces. Internet name servers implement the Domain Name System. The top hierarchy of the Domain Name System is served by the root name servers maintained by delegation by the Internet Corporation for Assigned Names and Numbers (ICANN). Below the root, Internet resources are organized into a hierarchy of domains, administered by the respective registrars and domain name holders. A DNS name server is a server that stores the DNS records, such as address (A, AAAA) records, name server (NS) records, and mail exchanger (MX) records for a domain name (see also List of DNS record types) and responds with answers to queries against its database.
Authoritative name server
Authoritative name server is a name server that gives answers in response to questions asked about names in a zone. An authoritative-only name server returns answers only to queries about domain names that have been specifically configured by the administrator. Name servers can also be configured to give authoritative answers to queries in some zones, while acting as a caching name server for all other zones.
An authoritative name server can either be a primary server (master) or a secondary server (slave). A primary server for a zone is the server that stores the definitive versions of all records in that zone. A secondary server for a zone uses an automatic updating mechanism to maintain an identical copy of the primary server’s database for a zone. Examples of such mechanisms include DNS zone transfers and file transfer protocols. DNS provides a mechanism whereby the primary for a zone can notify all the known secondaries for that zone when the contents of the zone have changed. The contents of a zone are either manually configured by an administrator, or managed using Dynamic DNS.
Every domain name appears in a zone served by one or more authoritative name servers. The fully qualified domain names of the authoritative name servers of a zone are listed in the NS records of that zone. If the server for a zone is not also authoritative for its parent zone, the server for the parent zone must be configured with a delegation for the zone.
When a domain is registered with a domain name registrar, the zone administrator provides the list of name servers (typically at least two, for redundancy) that are authoritative for the zone that contains the domain. The registrar provides the names of these servers to the domain registry for the top level domain containing the zone. The domain registry in turn configures the authoritative name servers for that top level domain with delegations for each server for the zone. If the fully qualified domain name of any name server for a zone appears within that zone, the zone administrator provides IP addresses for that name server, which are installed in the parent zone as glue records; otherwise, the delegation consists of the list of NS records for that zone.
Authoritative answer
A name server indicates that its response is authoritative by setting the Authoritative Answer ( AA ) bit in the response to a query on a name for which it is authoritative. Name servers providing answers for which they are not authoritative (for example, name servers for parent zones), do not set the AA bit.
Recursive query
If a name server cannot answer a query because it does not contain an entry for the host in its database, it may recursively query name servers higher up in the hierarchy. This is known as a recursive query or recursive lookup . In principle, authoritative name servers suffice for the operation of the Internet. However, with only authoritative name-servers operating, every DNS query must start with recursive queries at the root zone of the Domain Name System and each user system must implement resolver software capable of recursive operation.
Caching name server
Caching name servers (
DNS caches
) store DNS query results for a period of time determined in the configuration (time-to-live) of each domain-name record. DNS caches improve the efficiency of the DNS by reducing DNS traffic across the Internet, and by reducing load on authoritative name-servers, particularly root name-servers. Because they can answer questions more quickly, they also increase the performance of end-user applications that use the DNS.
Recursive name servers
resolve any query they receive, even if they are not authoritative for the question being asked, by consulting the server or servers that are authoritative for the question. Caching name servers are often also recursive name servers—they perform every step necessary to answer any DNS query they receive. To do this the name server queries each authoritative name-server in turn, starting from the DNS root zone. It continues until it reaches the authoritative server for the zone that contains the queried domain name. That server provides the answer to the question, or definitively says it can’t be answered, and the
caching resolver
then returns this response to the client that asked the question. The authority, resolving and caching functions can all be present in a DNS server implementation, but this is not required: a DNS server can implement any one of these functions alone, without implementing the others. Internet service providers typically provide caching resolvers for their customers. In addition, many home-networking routers implement caching resolvers to improve efficiency in the local network. Some systems utilize
nscd—
the name service caching daemon.
Microsoft networking
Name servers also exist on some Microsoft Windows networks where one host assumes the role of NetBIOS browse master and performs as a NBNS server. Small local area networks of Windows systems require no central name server, and generally perform name-resolution using a broadcast algorithm.
The Windows Internet Name Service (WINS) is a name service that translates NetBIOS names to numerical addresses.
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