Sexual Reproduction of Spiders Essay -- Biology Animal Insect Sex Mati

One of the largest issues in animal sexual reproduction is the conflict of interests between the female and the male of the species. For example, multiple mating has been shown to greatly increase the fertilization rate for the male, but recent studies have shown that multiple mating also benefits the female. The demonstrated benefit to the female is â€Å"sequential female choice;† that is, the ability (on the part of the female) to allow the fertilization of her egg clutch with more viable offspring. However, this presents an inherent conflict of interest in that sperm competition may lower the fertilization success rates of the species. Sexual cannibalism (when the female consumes the male near the time of copulation) is a striking manifestation of a sexual conflict of interest. If the female consumes the male prior to insemination, she gains the nutritional benefits but the male loses his ability to reproduce. However, if the female consumes the male after insemination, the costs and benefits to each party are not so clear. It is beneficial to both the male and female to increase the fecundity of the female, increasing the reproductive chances of the male as well, but if the female mates again the male loses any apparent benefit. Some spiders seem to have resolved this problem in favor of both sexes such as the redback spider, Latrodectus hasselti. Experiments involving polygamy in this species revealed that cannibalized males had greater fertilization success because these males mated longer and the cannibalistic females tended not to mate again. This shows that a compromise is struck between the two sexes. The female gains the benefit of the nutrition from the stoma of the male while the male limits the competition fro... ...or her offspring. Sexual cannibalism is found to greatly benefit fertilization. That is, if after copulation, the female eats the male, the amount of clutch sired becomes twice as much as in the cases when he survives. Finally, males who are cannibalized by females have a higher share of paternity. However, the probability of being cannibalized makes most males willing to sometimes avoid copulation, which greatly reduces sexual competition. The conflict of sexes remains unsolved, as female prefer to cannibalize males for benefits of the progeny, males always try to escape in order to fertilize more eggs of other females. Bibliography: Elgar, Mark A. and Schneider, Jutta M.. "Sexual cannibalism and sperm competition in the golden orb-web spider Nephila plumipes (Araneoidea): female and male perspectives." Behavioral Ecology, Vol. 12, No. 5, 2001. 547-552.

Common Biases and Errors in Decision-Making Process

COMMON BIASES AND ERRORS IN DECISION-MAKING PROCESS In addition to engaging in bounded rationality, an accumulating body of research tells us that decision makers allow systematic biases and errors to creep into their judgments. These come out of attempts to shortcut the decision process. To minimize effort and avoid difficult trade-offs, people tend to rely too heavily on experience, impulses, gut feelings, and convenient aâ‚ ¬? rules of thumb. aâ‚ ¬? In many instances, these shortcuts are helpful. However, they can lead to severe distortions from rationality.The following highlights the most common distortions. Overconfidence Bias:  Itaâ‚ ¬Ã¢â€ž ¢s been said that aâ‚ ¬? no problem in judgment and decision making is more prevalent and more potentially catastrophic than overconfidence. aâ‚ ¬? When weaâ‚ ¬Ã¢â€ž ¢re given factual questions and asked to judge the probability that our answers are correct, we tend to be far too optimistic. For instance, studies have fo und that, when people say theyaâ‚ ¬Ã¢â€ž ¢re 65 to 70% confident that theyaâ‚ ¬Ã¢â€ž ¢re right, they were actually correct only about 50% of the time. And when they say theyaâ‚ ¬Ã¢â€ž ¢re 100% sure, they tended to be 70 to 85% correct.From an organizational standpoint, one of the more interesting findings related to overconfidence is that those individuals whose intellectual and interpersonal abilities are weakest are most likely to overestimate their performance and ability. So as mangers and employees become more knowledgeable about an issue, the less likely they are to display overconfidence. Overconfidence is most likely to surface when organizational members are considering issues or problems that are outside their area of expertise. Anchoring Bias:  The anchoring bias is a tendency to fixate on initial information as a starting point.Once set, we then fail to adequately adjust for subsequent information. The anchoring bias occurs because our mind appears to give a d isproportionate amount of emphasis to the first information it receives. So initial impressions, ideas, process, and estimates carry undue weight relative to information received later. Anchors are widely used by professional people such as advertising writers, managers, politicians, real estate agents, and lawyersaâ‚ ¬Ã¢â‚¬ where persuasion skills are important For instance, in a mock jury trial, one set of jurors was asked by the plaintiffaâ‚ ¬Ã¢â€ž ¢s attorney to make an award in the range of Rs. million to Rs. 25 million. Another set of jurors was asked for an award in the range of Rs. 25 million to 75 million. Consistent with the anchoring bias, the median awards were Rs. 5 million versus Rs. 25 million in the two conditions. Consider the role of anchoring in negotiations and interviews. Any time a negotiation takes place, so does anchoring. As soon as someone states a number, your ability to objectively ignore that number has been compromised. For instance, when a prosp ective employer asks how much you were making in your prior job, your answer typically anchors the employeraâ‚ ¬Ã¢â€ž ¢s offer.Most of us understand this and upwardly aâ‚ ¬? adjustaâ‚ ¬? our previous salary in the hope that it will encourage our employer to offer us more. Anchoring can distort employment interviews. The initial information you might get interviewing a job candidate is likely to anchor your assessment of the applicant and unduly influence how you interpret information that you obtain later. Confirmation Bias:  The rational decision-making process assumes that we objectively gather information. But we donaâ‚ ¬Ã¢â€ž ¢t. We selectively gather information.The information bias represents a specific case of selective perception. We seek out information that reaffirms our past choices, and we discount information that contradicts past judgments. We also tend to accept information at face value that confirms our preconceived views, while being critical and skep tical of information that challenges these views. The information we gather is typically biased toward supporting views we already hold. This confirmation bias influences where we go to collect evidence because we tend to seek out places that are more likely to tell us what we want to hear.It also leads us to give too much weight to supporting information and too little to contradictory information. Availability Bias:  Many more people suffer from fear of flying than fear of driving in a car. The reason is that many people think flying is more dangerous. If flying on a commercial airline was as dangerous as driving, the equivalent of two 747s filled to capacity would have to crash every week, killing all aboard, to match the risk of being killed in a car accident.But the media give a lot more attention to air accidents, so we tend to overstate the risk of flying and understate the risk of driving. This illustrates an example of the availability bias, which is the tendency for peop le to base their judgments on information that is readily available to them. Events that evoke emotions, that are particularly vivid, or that have occurred more recently tend to be more available in our memory. As a result, we tend to be prone to overestimating unlikely events like an airplane crash.The availability bias can also explain why managers, when doing annual performance appraisals, tend to give more weight to recent behaviors of an employee than those behaviors of six or nine months ago. Escalation of Commitment Error:  Another distortion that creeps into decisions in practice is a tendency to escalate commitment when a decision stream represents a series of decisions. Escalation of commitment refers to staying with a decision even when there is clear evidence that itaâ‚ ¬Ã¢â€ž ¢s wrong.An example of this is of my friend, who has been dating a woman for about four years. He admitted that things werenaâ‚ ¬Ã¢â€ž ¢t going too well in their relationship; he informed m e that he was going to marry the woman. A bit surprised by his decision, I asked him why. He responded: aâ‚ ¬? I have a lot invested in the relationship! aâ‚ ¬? It has been well documented that individuals escalate commitment to a failing course of action when they view themselves as a responsible for the failure. That is they aâ‚ ¬? throw good money after badaâ‚ ¬? o demonstrate that their initial decision wasnaâ‚ ¬Ã¢â€ž ¢t wrong and to avoid having to admit they made a mistake. Escalation of commitment is also congruent with evidence that people try to appear consistent in what they say and do. Increasing commitment to previous actions conveys consistency. Escalation of commitment has obvious implications for managerial decisions. Many an organization has suffered large losses because a manager was determined to prove his or her original decision was right by continuing to commit resources to what was a lost cause from the beginning.In addition, consistency is a cha racteristic often associated with effective leaders. So managers, in an effort to appear effective, may be motivated to be consistent when switching to another course of action. In reality, effective managers are those who are able to differentiate between situations in which persistence will pay off and situations in which it will not. http://www. citeman. com/384-common-biases-and-errors-in-decision-making-process. html

Jan Van Eyck Madonna in the Church

Madonna in a Church is a small oil panel on oak by Flemish painter Jan van Check. Madonna in a church was made between c. 1438-1440. Van Check has been traditionally credited with the invention of painting in oils, and, although this is incorrect, there is no doubt that he was the real master of the technique. The use of oil paints is very significant in this artworks luminescent quality and presentation of space. The artist creates a new relationship between the viewer and the picture.There is an illusion of a modern, tatterdemalion's scene and through this new more attraction, lifelike approach, the viewer becomes connected to the painting, not Just in physical terms, but socially, spiritually and emotionally as well. † The minute we look at it the shimmering quality of the art stands out. Being only 12. 25†³ x 5. 5†³ it's clear why its elaboration is so astonishing. The painting is very long compared to its width, emphasizing the size of the Madonna and the tall st ructure of the church that it portrays.The artwork has brilliant intense warm colors, dominating brown and red and the light illustrated with light yellow. On Madonna in a Church, the artist represents a variety of subjects with striking legalism in microscopic detail. The pigment was suspended in a layer of oil that also trapped light, this way Van Check created a Jewel-like medium. On the Madonna's crown and Jewelry we see shiny precious metals and gems and also, with the help of this technique he could give a life like impression to light. The colors are so luminous that the passage of five hundred years has barely diminished them.There are so many details and elements to discover on the painting that the eye has a constant exercise inside the picture. From the first view we can tell that the artwork is narrative and descriptive. Van Check had a sharp edged look of the world but he put this look into a fictional environment. The painting was stolen in 1877 and the frame was not f ound. Despite this absence we still have an impression of a frame because the cathedral interior is viewed at an angle. From this perspective the doorway has a frame effect to the painting.The shape of the doorway is round, following the ceiling and with this circle effect leading our eyes to the main figure, Mary. † Van Check has followed traditional theology; his realist art displayed in iconic and allusive forms the Church's teachings and popular piety. Yet at the same time, he played with symbolism, which is evidently present in the artwork. The Madonna's size is surreal, very big in proportion to the interior of the exceptionally beautiful church. This is a symbolic niche, giving her all the importance. Byzantine painters used this method for the same purpose.In the background, angels appear to be singing from hymn books or saying Mass before her altar. † The image of light has a heavy vision, the rays of the sun come supernaturally from the north to strike through the glass and hit the floor with breathtaking realism. Two lolls of sunlight on the floor in front of Mary come from a direction that defies natural law. Therefore the light is mystical, a symbol of God. We can see it penetrating the church Just as the Holy Ghost entered and impregnated the body of the Virgin, in direct opposition to the laws of flesh.The perspective and lighting seem to be so natural, until we think about it we don't see that it's unnatural, and that it is actually a sacred light. Maybe this is a way to express that what is religious was incorporated into everyday life, that even a Heavenly light had to become like daylight under Jan Van Cock's paintbrush. The virgin takes her place in the center, gently swaying, she seem to follow her own gaze. Her hair is red; throughout the ages red-haired women have had significance in the arts. They are viewed as unique and mystical, Just like Mary.She has a beautiful tracery behind her: wooden carving, the stories of her life . It is especially important in the Northern Renaissance, because they used the Juxtaposition of the presented sacred character and then an object or artwork of the exact same personage on the picture, referring to Biblical times. We see a sculpture of Christ behind her, while the baby Jesus is in her arms. She is presented in the everyday life of those people living in the 15th century and part of their modern culture. The church is richly decorated, in the Gothic style.Jan Van Check pays attention to detail in his painting of architectural interiors, done with unrelenting accuracy. The church is an important symbol of Marry chastity. It's an Ideal church, Jan Van Cock's fantasy of a perfect interior to enthrone Mary. This is a way to represent the heavenly sphere in an environment that the people of the time period can recognize. Concluding from the small size of the painting, it was not a painting designed for a huge Gothic church where most paintings were much bigger in proporti on. It was probably made for a wealthy man at the time.In the Renaissance it was common for wealthy people to collect artworks, it had a social significance. Above this, religious paintings and prayer books were manifestations of commitment to prayer. The Flemish didn't limit their demonstration of piety to the public realm, the individuals commissioned artworks for private use in their homes as well. † Ideology of the time also influenced the painting. The Madonna is holding the child that is supposed to be Christ. Her face is turned away from the child, achieving a less engaged look. The scene is all about her.In Van Cock's painting, the child is a realistic baby; emphasizing the humanity of Christ. The interpretation of this can be the fact that Mary was a human, and in the Renaissance, humanism had a very big impact. After the neglected human dimension of the Middle Ages, the Renaissance brings humanity in focus again with the development of art, technology, and inventions . † Van Check gives Mary three roles: Mother of Christ, the personification of the Christian Church and Queen of Heaven, the latter apparent from her Jewel-studded crown.The painting is majestic and luminous, it lights up like a dream. But at the same time the message is both worldly and devout, the artist set out to satisfy both demands, but in a form of realism that contained within itself a playful, even ironic attitude towards the relations existing between individuals, society and religion. Sources: Graham, Jenny. Inventing van Check: the remaking of an artist for the modern age. Oxford: Berg, 2007. Print. Harrison, Craig. Jan van Check: the play of realism. London: Reaction Books ;, 1991. 188. Print.