ECOLOGICAL NICHE


ECOLOGICAL NICHE
In ecology, a niche is a term with a variety of meanings related to the behavior of a species living under specific environmental conditions. The ecological niche describes how an organism or population responds to the distribution of resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). “The type and number of variables comprising the dimensions of an environmental niche vary from one species to another…[and]…the relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts”.
The notion of ecological niche is central to ecological biogeography, which focuses on spatial patterns of ecological communities. “Species distributions and their dynamics over time result from properties of the species, environmental variation…, and interactions between the two — in particular the abilities of some species, especially our own, to modify their environments and alter the range dynamics of many other species.” Alteration of an ecological niche by its inhabitants is the topic of niche construction.
The majority of species exist in a standard ecological niche, but there are exceptions. A premier example of a non-standard niche filling species is the flightless, ground-dwelling kiwi bird of New Zealand, which feeds on worms and other ground creatures, and lives its life in a mammal niche. Island biogeography can help explain island species and associated unfilled niches.
GRINNELLIAN NICHE
The ecological meaning of niche comes from the meaning of niche as a recess in a wall for a statue, which itself is probably derived from the Middle French word nicher, meaning to nest. The term was coined by the naturalist Joseph Grinnell in 1917, in his paper “The niche relationships of the California Thrasher”. The Grinnellian niche concept embodies the idea that the niche of a species is determined by the habitat in which it lives and its accompanying behavioral adaptations. In other words, the niche is the sum of the habitat requirements and behaviors that allow a species to persist and produce offspring. For example, the behavior of the California Thrasher is consistent with the chaparral habitat it lives in—it breeds and feeds in the underbrush and escapes from its predators by shuffling from underbrush to underbrush. Its ‘niche’ is defined by the felicitous complementing of the thrasher’s behavior and physical traits (camouflaging color, short wings, strong legs) with this habitat.
This perspective of niche allows for the existence of both ecological equivalents and empty niches. An ecological equivalent to an organism is an organism from a different taxonomic group exhibiting similar adaptations in a similar habitat, an example being the different succulents found in American and African deserts, cactus and euphorbia. As another example, the Anolis lizards of the Greater Antilles are a rare example of convergent evolution, adaptive radiation, and the existence of ecological equivalents: the Anolis lizards evolved in similar microhabitats independently of each other and resulted in the same ecomorphs across all four islands.
ELTONIAN NICHE
In 1927 Charles Sutherland Elton, a British ecologist, defined a niche as follows: “The ‘niche’ of an animal means its place in the biotic environment, its relations to food and enemies.”
Elton classified niches according to foraging activities (“food habits”): “For instance there is the niche that is filled by birds of prey which eat small animals such as shrews and mice. In an oak wood this niche is filled by tawny owls, while in the open grassland it is occupied by kestrels. The existence of this carnivore niche is dependent on the further fact that mice form a definite herbivore niche in many different associations, although the actual species of mice may be quite different.”
HUTCHINSONIAN NICHE
The Hutchinsonian niche is an n-dimensional hypervolume, where the dimensions are environmental conditions and resources, that define the requirements of an individual or a species to practice “its” way of life, more particularly, for its population to persist. The “hypervolume” defines the multi-dimensional space of resources (e.g., light, nutrients, structure, etc.) available to (and specifically used by) organisms, and “all species other than those under consideration are regarded as part of the coordinate system.”
The niche concept was popularized by the zoologist G. Evelyn Hutchinson in 1957. Hutchinson wanted to know why there are so many types of organisms in any one habitat. His work inspired many others to develop models to explain how many and how similar coexisting species could be within a given community, and led to the concepts of ‘niche breadth’ (the variety of resources or habitats used by a given species), ‘niche partitioning’ (resource differentiation by coexisting species), and ‘niche overlap’ (overlap of resource use by different species).
Statistics were introduced into the Hutchinson niche by Robert MacArthur and Richard Levins using the ‘resource-utilization’ niche employing histograms to describe the ‘frequency of occurrence’ as a function of a Hutchinson coordinate. So, for instance, a Gaussian might describe the frequency with which a species ate prey of a certain size, giving a more detailed niche description than simply specifying some median or average prey size. One advantage in using statistics is illustrated in the figure, where it is clear that for the narrower distributions (top) there is no competition for prey between the extreme left and extreme right species, while for the broader distribution (bottom), niche overlap indicates competition exists between all species. For such a bell-shaped distribution, the position, width and form of the niche correspond to the mean, standard deviation and the actual distribution itself.
An organism free of interference from other species could use the full range of conditions (biotic and abiotic) and resources in which it could survive and reproduce which is called its fundamental niche. However, as a result of pressure from, and interactions with, other organisms (i.e. inter-specific competition) species are usually forced to occupy a niche that is narrower than this, and to which they are mostly highly adapted. This is termed the realized niche. Hutchinson used the idea of competition for resources as the primary mechanism driving ecology, but overemphasis upon this focus has proved to be a handicap for the niche concept.[13] In particular, overemphasis upon a species’ dependence upon resources has led to too little emphasis upon the effects of organisms on their environment, for instance, colonization and invasions.
The term adaptive zone was coined by the paleontologist George Gaylord Simpson to explain how a population could jump from one niche to another that suited it, jump to an ‘adaptive zone’, made available by virtue of some modification, or possibly a change in the food chain, that made the adaptive zone available to it without a discontinuity in its way of life because the group was ‘pre-adapted’ to the new ecological opportunity.
Hutchinson’s “niche” (a description of the ecological space occupied by a species) is subtly different from the “niche” as defined by Grinnell (an ecological role, that may or may not be actually filled by a species—see vacant niches).
A niche is a very specific segment of ecospace occupied by a single species. On the presumption that no two species are identical in all respects (called Hardin’s ‘axiom of inequality’ and the competitive exclusion principle, some resource or adaptive dimension will provide a niche specific to each species.[16] Species can however share a ‘mode of life’ or ‘autecological strategy’ which are broader definitions of ecospace. For example, Australian grasslands species, though different from those of the Great Plains grasslands, exhibit similar modes of life.
Once a niche is left vacant, other organisms can fill that position. For example, the niche that was left vacant by the extinction of the tarpan has been filled by other animals (in particular a small horse breed, the konik). Also, when plants and animals are introduced into a new environment, they have the potential to occupy or invade the niche or niches of native organisms, often outcompeting the indigenous species. Introduction of non-indigenous species to non-native habitats by humans often results in biological pollution by the exotic or invasive species.
The mathematical representation of a species’ fundamental niche in ecological space, and its subsequent projection back into geographic space, is the domain of niche modelling.
PARAMETERS
The different dimensions, or plot axes, of a niche represent different biotic and abiotic variables. These factors may include descriptions of the organism’s life history, habitat, trophic position (place in the food chain), and geographic range. According to the competitive exclusion principle, no two species can occupy the same niche in the same environment for a long time. The parameters of a realized niche are described by the realized niche width of that species.

MEANING OF EBOLA FEVER OR VIRUS


1. MEANING OF EBOLA FEVER OR VIRUS
Ebola virus disease (EVD) or Ebola hemorrhagic fever (EHF) is a disease of humans and other primates caused by an ebolavirus. Symptoms start two days to three weeks after contracting the virus, with a fever, sore throat, muscle pain, and headaches. Typically nausea, vomiting, and diarrhea follow, along with decreased functioning of the liver and kidneys. Around this time, affected people may begin to bleed both within the body and externally.
2. ORIGIN
The first known incidents of the Ebola virus were in 1976. There were two simultaneous outbreaks in Nzara in Sudan and Yambuku in Zaire (now the Democratic Republic of Congo). The name of the Ebola river near Yambuku was given to the new epidemic.
Outbreaks have mainly occured in remote villages in Central and West Africa, close to tropical rainforests.
3. BRIEF HISTORY OF FEVER RESERVIOUR
Bats are considered the most likely natural reservoir of the Ebola virus (EBOV); plants, arthropods, and birds have also been considered. Bats were known to reside in the cotton factory in which the first cases for the 1976 and 1979 outbreaks were employed, and they have also been implicated in Marburg virus infections in 1975 and 1980. Of 24 plant species and 19 vertebrate species experimentally inoculated with EBOV, only bats became infected. The absence of clinical signs in these bats is characteristic of a reservoir species. In a 2002–2003 survey of 1,030 animals including 679 bats from Gabon and the Republic of the Congo, 13 fruit bats were found to contain EBOV RNA fragments. As of 2005, three types of fruit bats (Hypsignathus monstrosus, Epomops franqueti, and Myonycteris torquata) have been identified as being in contact with EBOV. They are now suspected to represent the EBOV reservoir hosts. Antibodies against Ebola Zaire and Reston viruses have been found in fruit bats in Bangladesh, thus identifying potential virus hosts and signs of the filoviruses in Asia.
Between 1976 and 1998, in 30,000 mammals, birds, reptiles, amphibians, and arthropods sampled from outbreak regions, no ebolavirus was detected apart from some genetic traces found in six rodents (Mus setulosus and Praomys) and one shrew (Sylvisorex ollula) collected from the Central African Republic. Traces of EBOV were detected in the carcasses of gorillas and chimpanzees during outbreaks in 2001 and 2003, which later became the source of human infections. However, the high lethality from infection in these species makes them unlikely as a natural reservoir.
Transmission between natural reservoir and humans is rare, and outbreaks are usually traceable to a single case where an individual has handled the carcass of gorilla, chimpanzee, or duiker. Fruit bats are also eaten by people in parts of West Africa where they are smoked, grilled, or made into a spicy soup.
4. CAUSAVATIVE AGENT
EVD is caused by four of five viruses classified in the genus Ebolavirus, family Filoviridae, order Mononegavirales. The four disease-causing viruses are Bundibugyo virus (BDBV), Sudan virus (SUDV), Taï Forest virus (TAFV), and one called simply, Ebola virus (EBOV, formerly Zaire Ebola virus)). Ebola virus is the sole member of the Zaire ebolavirus species, and the most dangerous of the known Ebola disease causing viruses, as well as being responsible for the largest number of outbreaks. The fifth virus, Reston virus (RESTV), is not thought to be disease-causing in humans. The five Ebola viruses are closely related to the Marburg viruses.

5. MODE OF TRANSMISSION
The virus may be acquired upon contact with blood or bodily fluids of an infected animal (commonly monkeys or fruit bats). Spread through the air has not been documented in the natural environment. Fruit bats are believed to carry and spread the virus without being affected. Once human infection occurs, the disease may spread between people as well. Male survivors may be able to transmit the disease via semen for nearly two months. In order to make the diagnosis, typically other diseases with similar symptoms such as malaria, cholera, and other viral hemorrhagic fevers are first excluded. To confirm the diagnosis, blood samples are tested for viral antibodies, viral RNA, or the virus itself.
6. PREVALANCE RATE
The disease prevalence rate is in both Humoral and Cellular Immunity of man and as such body contacts of any such with an infected person, animal or object should be avoided.
7. FATALITY RATE
Ebola Virus Disease outbreaks have a case fatality rate of up to 90%.
8. PREVATIVE MEASURE
Since no none cure of the diseases have been found a number of preventive measures as outline below can be followed.
Behavioral changes
Ebola viruses are contagious, with prevention predominantly involving behavior changes, proper full-body personal protective equipment, and disinfection. Techniques to avoid infection involve not contacting infected blood or secretions, including from those who are dead. This involves suspecting and diagnosing the disease early and using standard precautions for all patients in the healthcare setting. Recommended measures when caring for those who are infected include isolating them, sterilizing equipment, and wearing protective clothing including masks, gloves, gowns, and goggles. Hand washing is important but can be difficult in areas where there is not even enough water for drinking.
Due to lack of proper equipment and hygienic practices, large-scale epidemics have occurred mostly in poor, isolated areas without modern hospitals or well-educated medical staff. Traditional burial rituals, especially those requiring embalming of bodies, should be discouraged or modified. Airline crews, who fly to these areas of the world, are taught to identify Ebola and isolate anyone who has symptoms.
Quarantine
Quarantine, also known as enforced isolation, is usually effective in decreasing spread. Governments often quarantine areas where the disease is occurring or individuals who may be infected. In the United States, the law allows quarantine of those infected with Ebola. The lack of roads and transportation may help slow the disease in Africa. During the 2014 outbreak, Liberia closed schools.
Vaccine
No vaccine is currently available for humans. The most promising candidates are DNA vaccines or vaccines derived from adenoviruses, vesicular stomatitis Indiana virus (VSIV) or filovirus-like particles (VLPs) because these candidates could protect nonhuman primates from ebolavirus-induced disease. DNA vaccines, adenovirus-based vaccines, and VSIV-based vaccines have entered clinical trials.
Vaccines have protected nonhuman primates. Immunization takes six months, which impedes the counter-epidemic use of the vaccines. Searching for a quicker onset of effectiveness, in 2003, a vaccine using an adenoviral (ADV) vector carrying the Ebola spike protein was tested on crab-eating macaques. Twenty-eight days later, they were challenged with the virus and remained resistant. A vaccine based on attenuated recombinant vesicular stomatitis virus (VSV) vector carrying either the Ebola glycoprotein or the Marburg glycoprotein in 2005 protected nonhuman primates, opening clinical trials in humans. The study by October completed the first human trial, over three months giving three vaccinations safely inducing an immune response. Individuals for a year were followed, and, in 2006, a study testing a faster-acting, single-shot vaccine began; this new study was completed in 2008. Trying the vaccine on a strain of Ebola that more resembles one that infects humans is the next step.
On 6 December 2011, the development of a successful vaccine against Ebola for mice was reported. Unlike the predecessors, it can be freeze-dried and thus stored for long periods in wait for an outbreak. An experimental vaccine made by researchers at Canada’s national laboratory in Winnipeg was used, in 2009, to pre-emptively treat a German scientist who might have been infected during a lab accident. However, actual EBOV infection could never be demonstrated without a doubt. Experimentally, recombinant vesicular stomatitis Indiana virus (VSIV) expressing the glycoprotein of EBOV or SUDV has been used successfully in nonhuman primate models as post-exposure prophylaxis.

9. YOUR OWN SUGGESTION ON HOW TO CURB THE SPREAD OF THE FEVER IN NIGERIA.
There is no specific treatment for the disease. Efforts to help those who are infected are supportive and include giving either oral rehydration therapy (slightly sweet and salty water to drink) or intravenous fluids. The disease has a high mortality rate, often killing between 50% and 90% of those infected with the virus. EVD was first identified in Sudan and the Democratic Republic of the Congo. The disease typically occurs in outbreaks in tropical regions of Sub-Saharan Africa. From 1976 (when it was first identified) through 2013, fewer than 1,000 people per year have been infected. The largest outbreak to date is the ongoing 2014 West Africa Ebola outbreak, which is affecting Guinea, Sierra Leone, Liberia, and Nigeria. As of August 2014, more than 1,750 suspected cases have been reported. Efforts are ongoing to develop a vaccine; however, none yet exists.
Lastly my own suggestion is that the Federal Government should increase the awareness and sensitization of the disease in the country. Also infested persons in the country should be isolated for the time being and treated immediately.

REFERENCES
1. Kuhn, Jens H.; Becker, Stephan; Ebihara, Hideki; Geisbert, Thomas W.; Johnson, Karl M.; Kawaoka, Yoshihiro; Lipkin, W. Ian; Negredo, Ana I et al. (2010). “Proposal for a revised taxonomy of the family Filoviridae: Classification, names of taxa and viruses, and virus abbreviations”. Archives of Virology 155 (12): 2083–103. doi:10.1007/s00705-010-0814-x. PMC 3074192. PMID 21046175.
2. Pattyn, S.; Jacob, W.; van der Groen, G.; Piot, P.; Courteille, G. (1977). “Isolation of Marburg-like virus from a case of haemorrhagic fever in Zaire”. Lancet 309 (8011): 573–4. doi:10.1016/s0140-6736(77)92002-5. PMID 65663.
3. Bowen, E. T. W.; Lloyd, G.; Harris, W. J.; Platt, G. S.; Baskerville, A.; Vella, E. E. (1977). “Viral haemorrhagic fever in southern Sudan and northern Zaire. Preliminary studies on the aetiological agent”. Lancet 309 (8011): 571–3. doi:10.1016/s0140-6736(77)92001-3. PMID 65662.
4. WHO. “Ebola virus disease”.
5. Nanbo, Asuka; Watanabe, Shinji; Halfmann, Peter; Kawaoka, Yoshihiro (4 Feb 2013). “The spatio-temporal distribution dynamics of Ebola virus proteins and RNA in infected cells”. Nature. doi:10.1038/srep01206.
6. Klenk & Feldmann 2004, p. 28
7. Feldmann, H. K. (1993). “Molecular biology and evolution of filoviruses”. Archives of virology. Supplementum 7: 81–100. ISSN 0939-1983. PMID 8219816. edit
8. Biomarker Database. Ebola virus. Korea National Institute of Health. Retrieved 2009-05-31.
9. Klenk & Feldmann 2004, pp. 33–35
10. Klenk & Feldmann 2004, p. 2

DISCUSS THE MAIN CHARACTERISTICS OF JEWISH EDUCATION


DISCUSS THE MAIN CHARACTERISTICS OF JEWISH EDUCATION
INTRODUCTION
Jewish education is the transmission of the tenets, principles and religious laws of Judaism. Education remains one of the highest precepts in Judaism and the value of education is strongly embedded in Jewish culture. Due to Judaism’s heavy emphasis on Torah study, many have commented that Judaism is characterized by “lifelong learning” that extends to adults as much as it does to children.
HISTORY
The tradition of Jewish education goes back to biblical times. One of the basic duties of Jewish parents is to provide for the instruction of their children. The obligation to teach one’s children is set forth in the first paragraph of the Shema Yisrael prayer: “Take to heart these instructions with which I charge you this day. Impress them upon your children. Recite them when you stay at home and when you are away, when you lie down and when you get up. Bind them as sign on your hand and let them serve as a symbol on your forehead; inscribe them on the doorposts of your house and your gates.” (Deut 6:6-9).
(Deut 32:7). The Book of Proverbs also contains many verses related to education: “My son, do not forget my teaching, but let your mind retain my commandments; For they will bestow on you length of days, years of life and well-being.“ (Prov 3:1-2).
Elementary school learning was regarded as compulsory by Simeon ben Shetah as early as 75 BCE and Joshua ben Gamla in 64 CE. The education of older boys and men in a beit midrash goes back to the Second Temple period. The importance of education is stressed in the Talmud, which states that children should begin school at six. The rabbis stated that they should not be beaten with a stick or cane, that older students should help those who were younger, and that children should not be kept from their lessons by other duties. According to Judah ben Tema, “At five years the age is reached for studying the Bible, at ten for studying the Mishnah, at thirteen for fulfilling the mitzvoth, at fifteen for studying the Talmud.” (Avot 5:21). In keeping with this tradition, Jews established their own schools or hired private tutors for their children until the end of the 18th century. Schools were housed in annexes or separate buildings close to the synagogue.[3]
Rabbi Meir Simcha of Dvinsk (in his Meshech Chochma) observes that God’s statement “[Abraham is blessed because] he will instruct his children and his house after him to follow in God’s ways to perform righteousness and justice” (Genesis 18:19) is an implicit mitzvah to teach Judaism.
THE MAIN CHARACTERISTICS OF JEWISH EDUCATION
Once children reach school-age, parents are faced with another important choice: to send them to public, private or Jewish day school. The day school movement, once limited to the Orthodox community, has grown by leaps and bounds over the last twenty years. According to the Partnership for Excellence in Jewish Education (PEJE), an organization dedicated to strengthening day school education in North America, there are currently 700 Jewish day schools in North America with an enrollment approaching 200,000 students.
While almost half of these schools affiliate with the Orthodox movement, the other roughly 350 include independent, non-denominational schools, Jewish Montessori-style schools, Solomon Schecter schools (affiliated with the Conservative movement), and Reform day schools. (The Reconstructionist movement is also currently planning its first day school.) While most of these schools are located in major metropolitan areas, some smaller Jewish communities, in modest-size cities like Reading, Pennsylvania, are building day school options.
Parents who send their children to supplementary (afternoon and Sunday) schools for their primary Jewish education are often quite surprised to discover that these institutions are very much changed since their own childhood days. Jewish educators are working hard to find the most effective ways to provide a Jewish education in only two to six hours per week and making strides towards creating innovative, effective models for Jewish learning. Many schools are turning towards more experiential education, in which students learn Jewish studies through the creative arts. Other schools take students for overnight Shabbatons (Shabbat retreats) several times during the year, immersing them in a Jewish learning (as well as social) experience.

CONCLUSION
Recent studies estimate a population of 650,000 Jewish middle and high school students. Most of these attend Jewish youth groups or participate in activities funded by Jewish youth organizations Jewish youth organizations. Many of these are Zionist youth movements. The various organizations differ in political ideology, religious affiliation, and leadership structure, although they all tend to be characterized by a focus on youth leadership.

REFERENCES
1. Jewish education
2. Jewish education
3. Jewish education
4. “Brandeis Report”. Brandeis Report. Retrieved 24 May 2014.
5. “About NFTY”. Retrieved January 9, 2012.
6. Jewish summer camps
7. “Camp Ramah – Beth El Synagogue Omaha, NE”. Webcache. Retrieved September 14, 2010.
8. “URJ Camp & Israel Programs”.
9. “URJ 6 Points Sports Academy”. Retrieved January 9, 2012.
10. “Kutz: NFTY’s Campus for Reform Jewish Teens”. Retrieved January 9, 2012.
11. “URJ Camp & Israel Programs Special Needs Programs”. Retrieved January 9, 2012.
12. “About the URJ Camp & Israel Programs”. Retrieved January 9, 2012.
13. Benyehuda.org
14. Bring It In – Israel

DISCUSS IN DETAILS SITUATIONAL/CONTINGENCY THEORIES OF LEADERSHIP. OF WHAT SIGNIFICANT OR APPLICATION HAS THIS THEORY TO THE ORGANIZATION.


DISCUSS IN DETAILS SITUATIONAL/CONTINGENCY THEORIES OF LEADERSHIP. OF WHAT SIGNIFICANT OR APPLICATION HAS THIS THEORY TO THE ORGANIZATION.
INTRODUCTION
Leadership has been described as “a process of social influence in which one person can enlist the aid and support of others in the accomplishment of a common task”. For example, some understand a leader simply as somebody whom people follow or as somebody who guides or directs others, while others define leadership as “organizing a group of people to achieve a common goal”.
Studies of leadership have produced theories involving traits, situational interaction, function, behavior, power, vision and values, charisma, and intelligence, among others.
An organization (or organisation) is an entity, such as an institution or an association, that has a collective goal and is linked to an external environment. The word is derived from the Greek word organon, itself derived from the better-known word ergon which means “organ”.
SITUATIONAL AND CONTINGENCY THEORIES
Situational theory also appeared as a reaction to the trait theory of leadership. Social scientists argued that history was more than the result of intervention of great men as Carlyle suggested. Herbert Spencer (1884) (and Karl Marx) said that the times produce the person and not the other way around. This theory assumes that different situations call for different characteristics; according to this group of theories, no single optimal psychographic profile of a leader exists. According to the theory, “what an individual actually does when acting as a leader is in large part dependent upon characteristics of the situation in which he functions.”
Some theorists started to synthesize the trait and situational approaches. Building upon the research of Lewin et al., academics began to normalize the descriptive models of leadership climates, defining three leadership styles and identifying which situations each style works better in. The authoritarian leadership style, for example, is approved in periods of crisis but fails to win the “hearts and minds” of followers in day-to-day management; the democratic leadership style is more adequate in situations that require consensus building; finally, the laissez-faire leadership style is appreciated for the degree of freedom it provides, but as the leaders do not “take charge”, they can be perceived as a failure in protracted or thorny organizational problems. Thus, theorists defined the style of leadership as contingent to the situation, which is sometimes classified as contingency theory. Four contingency leadership theories appear more prominently in recent years: Fiedler contingency model, Vroom-Yetton decision model, the path-goal theory, and the Hersey-Blanchard situational theory.
The Fiedler contingency model bases the leader’s effectiveness on what Fred Fiedler called situational contingency. This results from the interaction of leadership style and situational favorability (later called situational control). The theory defined two types of leader: those who tend to accomplish the task by developing good relationships with the group (relationship-oriented), and those who have as their prime concern carrying out the task itself (task-oriented). According to Fiedler, there is no ideal leader. Both task-oriented and relationship-oriented leaders can be effective if their leadership orientation fits the situation. When there is a good leader-member relation, a highly structured task, and high leader position power, the situation is considered a “favorable situation”. Fiedler found that task-oriented leaders are more effective in extremely favorable or unfavorable situations, whereas relationship-oriented leaders perform best in situations with intermediate favorability.
Victor Vroom, in collaboration with Phillip Yetton (1973) and later with Arthur Jago (1988), developed a taxonomy for describing leadership situations, which was used in a normative decision model where leadership styles were connected to situational variables, defining which approach was more suitable to which situation. This approach was novel because it supported the idea that the same manager could rely on different group decision making approaches depending on the attributes of each situation. This model was later referred to as situational contingency theory.
The path-goal theory of leadership was developed by Robert House (1971) and was based on the expectancy theory of Victor Vroom. According to House, the essence of the theory is “the meta proposition that leaders, to be effective, engage in behaviors that complement subordinates’ environments and abilities in a manner that compensates for deficiencies and is instrumental to subordinate satisfaction and individual and work unit performance”. The theory identifies four leader behaviors, achievement-oriented, directive, participative, and supportive, that are contingent to the environment factors and follower characteristics. In contrast to the Fiedler contingency model, the path-goal model states that the four leadership behaviors are fluid, and that leaders can adopt any of the four depending on what the situation demands. The path-goal model can be classified both as a contingency theory, as it depends on the circumstances, and as a transactional leadership theory, as the theory emphasizes the reciprocity behavior between the leader and the followers.
The situational leadership model proposed by Hersey and Blanchard suggests four leadership-styles and four levels of follower-development. For effectiveness, the model posits that the leadership-style must match the appropriate level of follower-development. In this model, leadership behavior becomes a function not only of the characteristics of the leader, but of the characteristics of followers as well.
Closely related to the situational approach is what has become known The contingency theory of leadership was proposed by the Austrian psychologist as contingency theory. Fred Edward Fiedler in his landmark 1964 article, “A Contingency Model of Leadership Effectiveness.”
The contingency theory emphasizes the importance of both the leader’s personality and the situation in which that leader operates. Fiedler and his associates studied leaders in a variety of contexts but mostly in military context and their model is based on their research findings.
They outline two styles of leadership:
• task-motivated and
• relationship-motivated.
Task refers to task accomplishment, and relationship-motivation refers to interpersonal relationships.
Fiedler measured leadership style with the Least Preferred Co-Worker Scale (LPC scale.) The leaders scoring high on this scale are relationship motivated and those scoring low are task motivated (Northouse, 2007, p.114).
CONTINGENCY THEORY is a class of behavioral theory that claims that there is no best way to organize a corporation, to lead a company, or to make decisions. Instead, the optimal course of action is contingent (dependent) upon the internal and external situation. A contingent leader effectively applies their own style of leadership to the right situation.
Central to contingency theory is concept of the situation, which is characterized by three factors:
• Leader-member relations, deals with the general atmosphere of the group and the feelings such as trust, loyalty and confidence that the group has for its leader.
• Task structure, is related to task clarity and the means to task accomplishment.
• The position power, relates to the amount of reward-punishment authority the leader has over members of the group.
These three factors determine the favorableness of various situations in organizations
Contingency theories are a class of behavioral theory that contend that there is no one best way of leading and that a leadership style that is effective in some situations may not be successful in others.
An effect of this is that leaders who are very effective at one place and time may become unsuccessful either when transplanted to another situation or when the factors around them change.
This helps to explain how some leaders who seem for a while to have the ‘Midas touch’ suddenly appear to go off the boil and make very unsuccessful decisions.

CONCLUSION
Situational theories lean towards the different styles of leadership. The type of leadership needed changes from situation to situation. Those leaders that could adapt to the different situations were the most sought after people.
Just having different styles of leadership isn’t enough. That person must be able to apply the leadership style to the various situations where they can take control and influence the people.
Contingency theory is similar to situational theory in that there is an assumption of no simple one right way. The main difference is that situational theory tends to focus more on the behaviors that the leader should adopt, given situational factors (often about follower behavior), whereas contingency theory takes a broader view that includes contingent factors about leader capability and other variables within the situation.
By looking at Hersey and Blanchard’s leadership styles you can see that situational leadership follows the same styles as the behavioral theories.

REFERENCE
• Fielder, F. E. (1964). A theory of leadership effectiveness. In L. Berkowitz (Ed.), Advances in experimental social psychology. New York: Academic Press.
• Fielder, F. E. The contribution of cognitive resources to leadership performance. Journal of Applied Social Psychology, vol. 16 (1986). pp. 532–545.
• Hersey, P. and Blanchard, K. H. An introduction to situational leadership. Training and Development Journal, vol. 23 (1969). pp. 26–34.
• House, R. J. Path–goal theory of leadership: Lessons, legacy, and a reformulated theory. Leadership Quarterly, vol. 7 (1996). pp. 323–352.
• Kerr, S. and Jermier, J. M. Substitutes for leadership: Their meaning and measurement. Organizational Behavior and Human Performance, vol. 22 (1978). pp. 375–403.
• Kim, H. and Yukl, G. Relationships of managerial effectiveness and advancement to self-reported and subordinate-reported leadership behaviors from the multiple-linkage model. Leadership Quarterly, vol. 6 (1995). pp. 361–377.
• Vroom, V. H. and Jago, A. G. Situation effects and levels of analysis in the study of leader participation. Leadership Quarterly, vol. 6 (1995). pp. 169–181.

DISCUSS DRUG ANTAGONISM AND DRUG INTERACTIONS


DISCUSS DRUG ANTAGONISM AND DRUG INTERACTIONS
INTRODUCTION
A drug is, in the broadest of terms, a chemical substance that has known biological effects on humans or other animals. Foods are generally excluded from this definition, in spite of their physiological effects on animal species.
In pharmacology, a drug is “a chemical substance used in the treatment, cure, prevention, or diagnosis of disease or used to otherwise enhance physical or mental well-being.” Drugs may be used for a limited duration, or on a regular basis for chronic disorders.
An interaction between two or more drugs that have opposite effects on the body. Drug antagonism may block or reduce the effectiveness of one or more of the drugs. Frequently, the effect of one drug is reduced or enhanced in the presence of another. Competitive antagonism, described earlier, is a common and important mechanism, which will be encountered frequently in this book. However, a variety of other mechanisms can account for inhibitory or facilitatory interactions between drugs. The following list includes the most important ones:
• chemical antagonism
• pharmacokinetic antagonism
• block of receptor–effector linkage
• Physiological antagonism.
CHEMICAL ANTAGONISM
Chemical antagonism refers to the uncommon situation where the two substances combine in solution; as a result, the effect of the active drug is lost. Examples include the use of chelating agents (e.g. dimercaprol) that bind to heavy metals and thus reduce their toxicity, and the use of the neutralising antibody infliximab which has an anti-inflammatory action due to its ability to sequester the inflammatory cytokine, tumour necrosis factor
PHARMACOKINETIC ANTAGONISM
Pharmacokinetic antagonism describes the situation in which the ‘antagonist’ effectively reduces the concentration of the active drug at its site of action. This can happen in various ways. The rate of metabolic degradation of the active drug may be increased (e.g. the reduction of the anticoagulant effect of warfarin when an agent that accelerates its hepatic metabolism, such as phenobarbital, is given. Alternatively, the rate of absorption of the active drug from the gastrointestinal tract may be reduced, or the rate of renal excretion may be increased. Interactions of this sort, are common and can be important in clinical practice.
BLOCK OF RECEPTOR–EFFECTOR LINKAGE
Non-competitive antagonism describes the situation where the antagonist blocks at some point, downstream from the receptor, the chain of events that leads to the production of a response by the agonist. For example, drugs such as verapamil and nifedipine prevent the influx of Ca2+ through the cell membrane) and thus block non-specifically the contraction of smooth muscle produced by other drugs. As a rule, the effect will be to reduce the slope and maximum of the agonist log concentration–response curve although it is quite possible for some degree of rightward shift to occur as well.
TYPES OF DRUG ANTAGONISM
Drug antagonism occurs by various mechanisms:
• chemical antagonism (interaction in solution)
• pharmacokinetic antagonism (one drug affecting the absorption, metabolism or excretion of the other)
• competitive antagonism (both drugs binding to the same receptors); the antagonism may be reversible or irreversible
• interruption of receptor–effector linkage
• Physiological antagonism (two agents producing opposing physiological effects).
DRUG ANTAGONISM ARRANGEMENT

DRUG INTERACTIONS
The specific interaction between drugs and their receptors is referred to as “drug action”, and the widespread changes in physiological or psychological function is referred to as “drug effect”.This can be likened to Principles of drug action as stated below
Mechanisms
With very few exceptions, in order for a drug to affect the function of a cell, an interaction at the molecular level must occur between the drug and some target component of the cell. In most cases the interaction consists of a loose, reversible binding of the drug molecule, although some drugs can form strong chemical bonds with their target sites, resulting in long-lasting effects. Three types of target molecules can be distinguished: (1) receptors, (2) macromolecules that have specific cellular functions, such as enzymes, transport molecules, and nucleic acids, and (3) membrane lipids.
Receptors
Receptors are protein molecules that recognize and respond to the body’s own (endogenous) chemical messengers, such as hormones or neurotransmitters. Drug molecules may combine with receptors to initiate a series of physiological and biochemical changes. Receptor-mediated drug effects involve two distinct processes: binding, which is the formation of the drug-receptor complex, and receptor activation, which moderates the effect. The term affinity describes the tendency of a drug to bind to a receptor; efficacy (sometimes called intrinsic activity) describes the ability of the drug-receptor complex to produce a physiological response. Together, the affinity and the efficacy of a drug determine its potency.
Differences in efficacy determine whether a drug that binds to a receptor is classified as an agonist or as an antagonist. A drug whose efficacy and affinity are sufficient for it to be able to bind to a receptor and affect cell function is an agonist. A drug with the affinity to bind to a receptor but without the efficacy to elicit a response is an antagonist. After binding to a receptor, an antagonist can block the effect of an agonist.
The degree of binding of a drug to a receptor can be measured directly by the use of radioactively labeled drugs or inferred indirectly from measurements of the biological effects of agonists and antagonists. Such measurements have shown that the following reaction generally obeys the law of mass action in its simplest form: drug + receptor ⇌ drug-receptor complex. Thus, there is a relationship between the concentration of a drug and the amount of drug-receptor complex formed.
The structure-activity relationship describes the connection between chemical structure and biological effect. Such a relationship explains the efficacies of various drugs and has led to the development of newer drugs with specific mechanisms of action. The contribution of the British pharmacologist Sir James Black to this field led to the development, first, of drugs that selectively block the effects of epinephrine and norepinephrine on the heart (beta blockers, or beta-adrenergic blocking agents) and, second, of drugs that block the effect of histamine on the stomach (H2-blocking agents), both of which are of major therapeutic importance.
Receptors for many hormones and neurotransmitters have been isolated and biochemically characterized. All these receptors are proteins, and most are incorporated into the cell membrane in such a way that the binding region faces the exterior of the cell. This allows the endogenous chemicals freer access to the cell. Receptors for steroid hormones (e.g., hydrocortisones and estrogens) differ in being located in the cell nucleus and therefore being accessible only to molecules that can enter the cell across the membrane.
Once the drug has bound to the receptor, certain intermediate processes must take place before the drug effect is measurable. Various mechanisms are known to be involved in the processes between receptor activation and the cellular response (also called receptor-effector coupling). Among the most important ones are the following: direct control of ion channels in the cell membrane, regulation of cellular activity by way of intracellular chemical signals, such as cyclic adenosine 3′,5′-monophosphate (cAMP), inositol phosphates, or calcium ions, and regulation of gene expression.
In the first type of mechanism, the ion channel is part of the same protein complex as the receptor, and no biochemical intermediates are involved. Receptor activation briefly opens the transmembrane ion channel, and the resulting flow of ions across the membrane causes a change in the transmembrane potential of the cell that leads to the initiation or inhibition of electrical impulses. Such mechanisms are common for neurotransmitters that act very rapidly. Examples include the receptors for acetylcholine and for other fast excitatory or inhibitory transmitter substances in the nervous system, such as glutamate and gamma-aminobutyric acid (GABA).
In the second mechanism, chemical reactions that take place within the cell trigger a series of responses. The receptor may control calcium influx through the outer cell membrane, thereby altering the concentration of free calcium ions within the cell, or it may control the catalytic activity of one or more membrane-bound enzymes. One of these enzymes is adenylate cyclase, which catalyzes the conversion of adenosine triphosphate (ATP) within the cell to cAMP, which in turn binds to and activates intracellular enzymes that catalyze the attachment of phosphate groups to other functional proteins; these may be involved in a wide variety of intracellular processes, such as muscle contraction, cell division, and membrane permeability to ions. A second receptor-controlled enzyme is phosphodiesterase, which catalyzes the cleavage of a membrane phospholipid, phosphatidylinositol, releasing the intracellular messenger inositol triphosphate. This substance in turn releases calcium from intracellular stores, thus raising the free calcium ion concentration. Regulation of the concentration of free calcium ions is important because, like cAMP, calcium ions control many cellular functions. (For more information on intracellular signaling molecules, see second messenger and kinase.)
In the third type of mechanism, which is peculiar to steroid hormones and related drugs, the steroid binds to a receptor that consists primarily of nuclear proteins. Because this interaction occurs inside the cell, agonists for this receptor must be able to cross the cell membrane. The drug-receptor complex acts on specific regions of the genetic material deoxyribonucleic acid (DNA) in the cell nucleus, resulting in an increased rate of synthesis for some proteins and a decreased rate for others. Steroids generally act much more slowly (hours to days) than agents that act by either of the two other mechanisms.
Many receptor-mediated events show the phenomenon of desensitization, which means that continued or repeated administration of a drug produces a progressively smaller effect. Among the complex mechanisms involved are conversion of the receptors to a refractory (unresponsive) state in the presence of an agonist, so that activation cannot occur, or the removal of receptors from the cell membrane (down-regulation) after prolonged exposure to an agonist. Desensitization is a reversible process, although it can take hours or days for receptors to recover after down-regulation. The converse process (up-regulation) occurs in some instances when receptor antagonists are administered. These adaptive responses are undoubtedly important when drugs are given over a period of time, and they may account partly for the phenomenon of tolerance (an increase in the dose needed to produce a given effect) that occurs in the therapeutic use of some drugs.

CONCLUSION
A drug whose efficacy and affinity are sufficient for it to be able to bind to a receptor and affect cell function is an agonist. A drug with the affinity to bind to a receptor but without the efficacy to elicit a response is an antagonist. Drugs produce harmful as well as beneficial effects, and decisions about when and how to use them therapeutically always involve the balancing of benefits and risks. Drugs approved for human use are divided into those available only with a prescription and those that can be bought freely over the counter. The availability of drugs for medical use is regulated by law.
Drug treatment is the most frequently used type of therapeutic intervention in medicine. Its power and versatility derive from the fact that the human body relies extensively on chemical communication systems to achieve integrated function between billions of separate cells. The body is therefore highly susceptible to the calculated chemical subversion of parts of this communication network that occurs when drugs are administered.

REFERENCES
1. “Pharmacology Guide: In vitro pharmacology: concentration-response curves.” GlaxoWellcome. Retrieved on December 6, 2007.
2. Hopkins AL, Groom CR (2002). “The druggable genome”. Nature reviews. Drug discovery 1 (9): 727–30. doi:10.1038/nrd892. PMID 12209152.
3. T. Kenakin (2006) A Pharmacology Primer: Theory, Applications, and Methods. 2nd Edition Elsevier ISBN 0-12-370599-1
4. May LT, Avlani VA, Sexton PM, Christopoulos A (2004). “Allosteric modulation of G protein-coupled receptors”. Curr. Pharm. Des. 10 (17): 2003–13. doi:10.2174/1381612043384303. PMID 15279541.
5. Christopoulos A (2002). “Allosteric binding sites on cell-surface receptors: novel targets for drug discovery”. Nature reviews. Drug discovery 1 (3): 198–210. doi:10.1038/nrd746. PMID 12120504.
6. Bleicher KH, Green LG, Martin RE, Rogers-Evans M (2004). “Ligand identification for G-protein-coupled receptors: a lead generation perspective”. Curr Opin Chem Biol 8 (3): 287–96. doi:10.1016/j.cbpa.2004.04.008. PMID 15183327.
7. Rees S, Morrow D, Kenakin T (2002). “GPCR drug discovery through the exploitation of allosteric drug binding sites”. Recept. Channels 8 (5–6): 261–8. doi:10.1080/10606820214640. PMID 12690954.

DIFFERENCIATE BETWEEN RALPH TYLER’S LINEAR OR OBJECTIVE MODEL AND WHEELER’S CYCLIC MODEL, TABA MODEL AND THE SITUATIONAL MODEL.


DIFFERENCIATE BETWEEN RALPH TYLER’S LINEAR OR OBJECTIVE MODEL AND WHEELER’S CYCLIC MODEL, TABA MODEL AND THE SITUATIONAL MODEL.
INTRODUCTION
Models are several concepts that can guide the development and review of all types of curricula at both the state and national levels.
RALPH TYLER’S LINEAR OR OBJECTIVE MODEL
Objective model; proposed by Ralph Tyler in 1949, is also referred to as the classical, rational or academic model which contains content that is based on specific objectives (Urebvu, 1990). It follows a logical and sequential as well as shows a relation among curriculum components. The objectives specify the expected learning outcomes in terms of specific measurable behaviors. The model is comprised of four main steps which include, agreeing on broad aims which are analyzed into objectives, secondly, constructing a curriculum to achieve these objectives, followed by the refining of the curriculum in practice through testing its capacity in achieving its objectives, and lastly, communicating the curriculum to implementers through the conceptual framework of the objectives (Urebvu, 1990).
It is important to note that the objective model was an eye opener to the scholars such as Tyler and therefore contributes massively in Tyler’s model of curriculum design and it is for this reason that Tyler’s model of curriculum process is sometimes called the means-objective model. The model is linear in nature, starting from objectives and ending with evaluation. In this model, evaluation is terminal in the sense that, objectives form the basis for the selection and organization of learning experiences. Objectives also form the basis for assessing the curriculum and are derived from the learner’s contemporary life and subject specialist (Tyler, 1949).
Tyler’s model for curriculum designing is based on the following four questions: What educational purposes should the school seek to attain? What educational experiences can be provided that is likely to attain these purposes? How can these educational experiences be effectively organized? How can we determine whether these purposes are being attained?
To Tyler, evaluation is a process by which one matches the initial expectation with the outcomes. It is done at each stage of the curriculum design and content, materials and methodology are derived from the objectives.
WHEELER’S CYCLIC MODEL
Wheeler’s model is a cyclical model. The key elements are analyzing the initial situation, identifying aims and objectives, selecting and organizing content, selecting and organizing learning activities, and selecting an evaluation or assessment process. This model which Wheeler called the circular model has five procedures which are: Selecting an objective, choosing learning experience, choosing content, organizing and integrating learning experience and content, and evaluating.
Wheeler (1967) contends that, aims should be discussed as behaviors referring to the end product of learning which yields the ultimate goals and these ultimate goals can as well be thought of as outcomes, additionally wheeler says that aims are formulated from the general to the specific in curriculum planning. This results in the formulation of objectives at both an enabling and a terminal level. Content is distinguished from the learning experiences which determine that content.
TABA MODEL AND THE SITUATIONAL MODEL.
Does the Situational Model bring us any closer to a workable and useful model to guide our curriculum work? Certainly it asks us to consider the context of curriculum and this is important. If we go back to our original view of curriculum as the translation of educational ideas into practice then we simply cannot discount the importance of context and the external and internal factors that impinge on the contexts in which we work. But does the Situational Model lock us into another series of five steps which cannot deal with all the complexity that Holt portrays?
I would argue that we should abandon the search for models. What we could do is to use the work of Skilbeck and others to define the essential Elements of curriculum. These would be
Situational analysis
Statements of intent (aims, objectives, outcomes)
Content
Implementation and organisational strategies
Assessment
Monitoring and evaluation.

THE DIFFERENCES BETWEEN ALL
Firstly the cyclical model has a feedback mechanism as compared to the objective model, in the sense that it provides students with ways to measure their progress or accuracy.
Whenever there is new information which needs to be incorporated in the curriculum, the cyclic model readily incorporates it in the curriculum which is never the case in the objective model which seems to be impossible to receive or incorporate more information. This makes the spherical model to be more flexible as compared to the objective model which is more on a rigid side.
The other difference is that cyclical models present the curriculum design process as a continuing activity, which is constantly in a state of change as new information, and practices become available, while in the objective model it is hard to determine continuity is possible or not.
In addition Cyclical models emphasize the importance of Situational Analysis, so that the subsequent curriculum will accurately reflect the needs of the learners for whom it is intended and at the right time and the right place, which is a difficult thing to do in the objective model because of the its rigidity to adjust and suite the intended learners.

CONCLUSION
Probably the most well-known curriculum model is Ralph Tyler’s Objectives or Rational Planning Model. This is clearly a model for the curriculum or a prescriptive model. It sets out what curriculum workers should do. Tyler’s work Basic Principles of Curriculum and Instruction was first published in 1949. Rumour has it that Tyler left his lectures notes lying around and his students thought they were so good that they had them published. Perhaps this is something to which we should all aspire!
For Tyler the curriculum process involved four fundamental questions. It was a rational and orderly process of answering the following questions.
• What educational purposes should the school seek to attain?
• What educational experiences are likely to attain the purposes?
• How can these educational experiences be organised effectively?
• How can we determine whether these purposes are being attained?
The ‘purposes’ in the first of these questions became known as objectives and hence the model became known as the Objectives Model. Objectives were to be written in terms of changed learner behaviour which could be readily measured. Tyler’s work advocated a broad view of objectives but many of those that followed him supported a more narrow view. In the United States, in particular, there was strong support for the use of ‘behavioural objectives’ where behaviours had to be clearly specified in objectives which used verbs such as to write, to recite and to identify. Verbs such as to know, to understand and to appreciate were not to be used.
The Objectives Model attracted much criticism. It was claimed that writing objectives was difficult and time consuming, particularly in the form demanded by writers like Mager (1962) who argued that each objective had to contain a statement of the ‘behaviour’ to be attained, the’ conditions’ under which it would be demonstrated and the ‘standards’ by which it would be judged.

REFERENCES
Norton, J.K., & Norton, M.A. (1976). Foundations of Curriculum Building. Boston: Ginn.
Tyler, R.W (1949). Basic Principles of curriculum and Instruction. Chicago: University of
Chicago Press.
Urevbu, A. (1994). Curriculum Studies. Harlow: Longman House.
Wheeler, D.K (1967). Curriculum Process. London: University of London Press.
Http//www. wikipedia.org/wiki/Creative-curriculum studies and organization, accessed: 23-10-2009

CRITICALLY EXAMINE RELATIVE EFFECTIVENESS OF HUMAN ENGINEERING OR ERGONOMICS IN RELATION TP NIGERIA ECONOMIC PRODUCTIVITY LEVEL


CRITICALLY EXAMINE RELATIVE EFFECTIVENESS OF HUMAN ENGINEERING OR ERGONOMICS IN RELATION TP NIGERIA ECONOMIC PRODUCTIVITY LEVEL
INTRODUCTION
Human engineering can be describe as an applied science that coordinates the design of devices, systems, and physical working conditions with the capacities and requirements of the worker.
The field of ergonomics is based on scientific studies of ordinary people in work situations and is applied to the design of processes and machines, to the layout of work places, to methods of work, and to the control of the physical environment, in order to achieve greater efficiency of both men and machines An example of an ergonomics study is the evaluation of the effects of screwdriver handle shape, surface material and workpiece orientation on torque performance, finger force distribution and muscle activity in a maximum screwdriving torque task. Another example of an ergonomics study is the effects of shoe traction and obstacle height on friction. Similarly, many topics in ergonomics deal with the actual science of matching man to equipment and encompass narrower fields such as Engineering Psychology.
At one point in time, the term human factors was used in place of ergonomics in Europe. Human factors involve interdisciplinary scientific research and studies to seek to realize greater recognition and understanding of the worker’s characteristics, needs, abilities, and limitations when the procedures and products of technology are being designed. This field utilizes knowledge from several fields such as mechanical engineering, psychology, and industrial engineering to design instruments.
Human factors is broader than engineering psychology, which is focused specifically on designing systems that accommodate the information-processing capabilities of the brain.
Although the work in the respective fields differs, there are some similarities between these. These fields share the same objectives which are to optimize the effectiveness and efficiency with which human activities are conducted as well as to improve the general quality of life through increased safety, reduced fatigue and stress, increased comfort, and satisfaction.
EFFECTIVENESS OF HUMAN ENGINEERING
1. Human Engineers contribute to the design of a variety of products, including dental and surgical implements, cameras, toothbrushes and bucket seats for cars.
2. They have been involved in the redesign of the mailbags used by letter carriers. More than 20 percent of letter carriers suffer from musculoskeletal problems such as lower back pain from carrying mailbags slung over their shoulders.
3. A mailbag with a waist-support strap, and a double bag that requires the use of both shoulders, have been showed to reduce muscle fatigue.
4. Research by human engineering has demonstrated that using cell phones while driving degrades performance by increasing driver reaction time, particularly among older drivers, and can lead to higher accident risk among drivers of all ages. These and similar research findings are instigating state regulation of cell phone use.

SUMMARY
The term human-factors engineering is used to designate equally a body of knowledge, a process, and a profession. As a body of knowledge, human-factors engineering is a collection of data and principles about human characteristics, capabilities, and limitations in relation to machines, jobs, and environments. As a process, it refers to the design of machines, machine systems, work methods, and environments to take into account the safety, comfort, and productiveness of human users and operators. As a profession, human-factors engineering includes a range of scientists and engineers from several disciplines that are concerned with individuals and small groups at work.

CAUSES AND REMEDY OF TEENAGE PREGNANCY IN NIGERIA


CAUSES AND REMEDY OF TEENAGE PREGNANCY IN NIGERIA

INTRODUCTION
Teenage pregnancy is pregnancy in human females under the age of 20 at the time that the pregnancy ends. A pregnancy can take place in a pubertal female before menarche (the first menstrual period), which signals the possibility of fertility, but usually occurs after menarche. In well-nourished girls, menarche usually takes place around the age of 12 or 13.
A teenager, or teen, is a young person whose age falls within the range from thirteen through nineteen. They are called teenagers because their age number ends in “teen”. Someone aged 18 or 19 is also considered a young adult. Usage by ordinary people varies, and also varies in different societies. Most societies traditionally had a formal ceremony to mark the change from childhood to adulthood. During puberty, rapid mental and physical development occurs. Adolescence is the name for this transition period from childhood to adulthood.
CAUSES OF TEENAGE PREGNANCY IN NIGERIA
General
In some societies in Nigeria, early marriage and traditional gender roles are important factors in the rate of teenage pregnancy. The average marriage age differs by states, and states where teenage marriages are common experience higher levels of teenage pregnancies. In katsina state, early marriage and pregnancy is more common in traditional rural communities than cities.[18] The lack of education on safe sex, whether it is from parents, schools, or otherwise, is a cause of teenage pregnancy. Many teenagers are not taught about methods of birth control and how to deal with peers who pressure them into having sex before they are ready. Many pregnant teenagers do not have any cognition of the central facts of sexuality.
Following are some of the contributing factors or causes of teenage pregnancy in Nigeria:
1. Lack of Parental Guidance: Most people evade their children from talking about sex. In some cases, they provide false information regarding sex and discourage their children to participate in any informative discussion about sex. In some cases, teenage mothers are not well educated about sex before getting pregnant
2. Adolescent Sexual Behavior: Among the adolescents, peer pressure is a major factor that encourages the teenage boys and girls to indulge in sexual activities.
3. Inadequate Knowledge about Safe Sex: Most adolescents are unaware of safe sex. They probably have no access to the traditional methods of preventing pregnancy.
4. Exploitation by Older Men: This is another major factor that contributes to pregnancy among the teenagers. Those girls who date older men are more likely to become pregnant before they attain womanhood. Rape, sexual exploitations etc. also takes place that leads to unwanted pregnancy among teenage girls.

5. Socio Economic Factors: Teenage girls who belong to the poor families are more likely to become pregnant. Researchers have found that even in the developed countries teenage pregnancy occurs most commonly among the deprived sections.
6. Lack of supervision: Lack of supervision before teens are ready for independence is one of the causes of teenage pregnancy. Adolescents push boundaries. Look, I know it is easier to let your kid go hang at the mall or wander around an outside shopping area than it is to lay down the rules and stick by them. But if they aren’t at the mall for something specific, they have no business being there.
Knowing where your teens are going and whom they are with is basic Parenting 101. If you don’t know the kids they are hanging out with, get to know them. Allow your teen to have friends over; then make sure you are checking on them regularly down in that basement!
7. Low self-esteem: Low self-esteem is among the causes of teen pregnancy. Children who are not shown love and affection from parents will seek it out with their peer group. Many adolescents report feeling pressured by their peers to have sex before they are ready.
8. Families with two parents: Families with two parents in the home have a lower incidence of teen pregnancies. However, even as a single parent, you can still extend the love, affection, and care your child needs. As a single parent you have less time for yourself, but your child needs a positive role model.
9. Role of drug and alcohol use: Inhibition-reducing drugs and alcohol may possibly encourage unintended sexual activity. If so, it is unknown if the drugs themselves directly influence teenagers to engage in riskier behavior, or whether teenagers who engage in drug use are more likely to engage in sex. Correlation does not imply causation. The drugs with the strongest evidence linking them to teenage pregnancy are alcohol, cannabis, “ecstasy” and other substituted amphetamines. The drugs with the least evidence to support a link to early pregnancy are opioids, such as heroin, morphine, and oxycodone, of which a well-known effect is the significant reduction of libido – it appears that teenage opioid users have significantly reduced rates of conception compared to their non-using, and alcohol, “ecstasy”, cannabis, and amphetamine using peers.
10. Lack of contraception: Adolescents may lack knowledge of, or access to, conventional methods of preventing pregnancy, as they may be too embarrassed or frightened to seek such information. Contraception for teenagers presents a huge challenge for the clinician
According to The Encyclopedia of Women’s Health, published in 2004, there has been an increased effort to provide contraception to adolescents via family planning services and school-based health, such as HIV prevention education.
11. Age discrepancy in relationships: Teenage girls in relationships with older boys, and in particular with adult men, are more likely to become pregnant than teenage girls in relationships with boys their own age. They are also more likely to carry the baby to term rather than have an abortion. This study found that, compared with nonabused mothers, abused adolescent mothers initiated sex earlier, had sex with much older partners, and engaged in riskier, more frequent, and promiscuous sex.
12. Sexual abuse: Studies from NGOs in Nigeria have found that 11–20% of pregnancies in teenagers are a direct result of rape, while about 60% of teenage mothers had unwanted sexual experiences preceding their pregnancy. Before age 15, a majority of first-intercourse experiences among females are reported to be non-voluntary; the Guttmacher Institute found that 60% of girls who had sex before age 15 were coerced by males who on average were six years their senior. One in five teenage fathers admitted to forcing girls to have sex with them.
Multiple studies have indicated a strong link between early childhood sexual abuse and subsequent teenage pregnancy in industrialized countries. Up to 70% of women who gave birth in their teens were molested as young girls; by contrast, 25% of women who did not give birth as teens were molested.
13. Dating violence: Studies have indicated that adolescent girls are often in abusive relationships at the time of their conceiving. They have also reported that knowledge of their pregnancy has often intensified violent and controlling behaviors on part of their boyfriends. Girls under age 18 are twice as likely to be beaten by their child’s father as women over age 18.
In a study of 379 pregnant or parenting teens and 95 teenage girls without children, 62% of girls aged 11–15 and 56% of girls aged 16–19 reported experiencing domestic violence at the hands of their partners. Moreover, 51% of the girls reported experiencing at least one instance where their boyfriend attempted to sabotage their efforts to use birth control.
13. Socioeconomic factors: Teenage pregnancy has been defined predominantly within the research field and among social agencies as a social problem. Poverty is associated with increased rates of teenage pregnancy. Economically poor countries such as Niger and Bangladesh have far more teenage mothers compared with economically rich countries such as Switzerland and Japan.
14.Childhood environment: Women exposed to abuse, domestic violence, and family strife in childhood are more likely to become pregnant as teenagers, and the risk of becoming pregnant as a teenager increases with the number of adverse childhood experiences. According to a 2004 study, one-third of teenage pregnancies could be prevented by eliminating exposure to abuse, violence, and family strife. The researchers note that “family dysfunction has enduring and unfavorable health consequences for women during the adolescent years, the childbearing years, and beyond.” When the family environment does not include adverse childhood experiences, becoming pregnant as an adolescent does not appear to raise the likelihood of long-term, negative psychosocial consequences. Studies have also found that boys raised in homes with a battered mother, or who experienced physical violence directly, were significantly more likely to impregnate a girl.
Studies have also found that girls whose fathers left the family early in their lives had the highest rates of early sexual activity and adolescent pregnancy. Girls whose fathers left them at a later age had a lower rate of early sexual activity, and the lowest rates are found in girls whose fathers were present throughout their childhood. Even when the researchers took into account other factors that could have contributed to early sexual activity and pregnancy, such as behavioral problems and life adversity, early father-absent girls were still about five times more likely in the United States and three times more likely in New Zealand to become pregnant as adolescents than were father-present girls.
15. Low educational status: Low educational expectations have been pinpointed as a risk factor. A girl is also more likely to become a teenage parent if her mother or older sister gave birth in her teens. A majority of respondents in a 1988 Joint Center for Political and Economic Studies survey attributed the occurrence of adolescent pregnancy to a breakdown of communication between parents and child and also to inadequate parental supervision.
16. Peer Pressure: During adolescence, teenagers often feel pressure to make friends and fit in with their peers. Many times these teens let their friends influence their decision to have sex even when they do not fully understand the consequences associated with the act. Teenagers have sex as a way to appear cool and sophisticated, but in some cases the end result is an unplanned teen pregnancy. The Kaiser Family Foundation states that more than 29 percent of pregnant teens reported that they felt pressured to have sex, and 33 percent of pregnant teens stated that they felt that they were not ready for a sexual relationship, but proceeded anyway because they feared ridicule or rejection.

PREVENTION
Many health educators have argued that comprehensive sex education would effectively reduce the number of teenage pregnancies, although opponents argue that such education encourages more and earlier sexual activity. Interventions combining education and contraceptives appear to reduce unplanned teenage pregnancy; however no one intervention yet stands out as the most effective.
Preventing Teenage Pregnancy
The only way to be sure you won’t get pregnant is not to have sexual intercourse. However, there are many methods to reduce your chances of becoming pregnant if you are sexually active.
1. Prescription Birth Control
Prescription birth control is available through your doctor or a women’s health clinic.
An IUD is a device a doctor implants in your uterus. Hospitalization is not required. The IUD prevents a fertilized egg from attaching to the uterus. It has a 99 percent rate of effectiveness (Planned Parenthood, 2007).
Several birth control methods affect hormone levels in your body, so you’re less likely to get pregnant. The most effective is a birth control implant, a very small plastic stick that is inserted under the skin of your arm. Implants stay in place for up to three years. They have a 95 percent rate of effectiveness (Planned Parenthood, 2007).
The diaphragm and cervical cap are devices you place in your vagina when you’re going to have sex. They block sperm from entering your uterus. The effectiveness of these devices is 76 to 85 percent (Planned Parenthood, 2007).
2. Over-the-Counter Birth Control
You can also buy over-the-counter birth control at a drugstore and some supermarkets. These methods are not as effective as prescription birth control, but they do reduce your chance of getting pregnant.
3. Condoms
Teen pregnancy rates have been dropping in the United States for at least 20 years. Experts think this is because more sexually active teens use condoms. Proper use of a condom can keep you from getting pregnant. Condoms also protect you from many sexually transmitted diseases when used correctly. The effectiveness of condoms is 76 to 85 percent (Planned Parenthood, 2007).
4. Spermicidal Foam
Sponges treated with spermicide also block sperm from entering your uterus. Used properly, these methods prevent pregnancy with an effectiveness of 75 to 85 percent (Planned Parenthood, 2007).
5. Morning-After Pill
Available in the brands Plan B One-Step, Ela, and Next Choice, this medicine contains hormones that prevent your body from releasing eggs into your uterus and irritate the lining of the uterus to inhibit implantation. Eggs have to come into contact with sperm for you to get pregnant and need to implant in order to start developing properly. The morning-after pill might be a good choice for you if you think your regular birth control didn’t work or you weren’t using birth control. Women 17 and older do not need a prescription for the morning-after pill. The effectiveness of the morning-after pill is 89 percent (Planned Parenthood, 2012).
6. Teen Pregnancy Prevention Programs
According to a study published in the Journal of Adolescent Health in 2008, “Adolescents who received comprehensive sex education had lower risk of pregnancy than adolescents who received abstinence-only or no sex education” (JAH, 2008).
Many communities offer counseling and support programs that help prevent teen pregnancy. These groups can provide information on birth control and help teens understand their own sexual limits so they don’t get into situations where they might have unprotected sex and get pregnant. Some programs offer peer counseling, since it might feel more comfortable talking to someone your own age. Contact your health department for information on programs in your area.

CONCLUSION
Pregnant teenagers face many of the same obstetrics issues as other women. There are, however, additional medical concerns for mothers aged under 15. For mothers aged 15–19, risks are associated more with socioeconomic factors than with the biological effects of age.
Several studies have examined the socioeconomic, medical, and psychological impact of pregnancy and parenthood in teens. Life outcomes for teenage mothers and their children vary; other factors, such as poverty or social support, may be more important than the age of the mother at the birth. Many solutions to counteract the more negative findings have been proposed. Teenage parents who can rely on family and community support, social services and child-care support are more likely to continue their education and get higher paying jobs as they progress with their education. it was recommended that since the parents has a greater role to play in the life of adolescent therefore parents should maintain stable and positive relationship with their children. And also parents encourage deep religious spiritual affiliation and realistic academic expectation.

MEANING OF ALZEHEIMER


1. MEANING OF ALZEHEIMER
Alzheimer’s disease (AD), also known in medical literature as Alzheimer disease, is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death. It was first described by German psychiatrist and neuropathologist Alois Alzheimer in 1906 and was named after him.[1] Most often, AD is diagnosed in people over 65 years of age, although the less-prevalent early-onset Alzheimer’s can occur much earlier. In 2006, there were 26.6 million people worldwide with AD. Alzheimer’s is predicted to affect 1 in 85 people globally by 2050.
Although Alzheimer’s disease develops differently for every individual, there are many common symptoms. Early symptoms are often mistakenly thought to be ‘age-related’ concerns, or manifestations of stress. In the early stages, the most common symptom is difficulty in remembering recent events, known as short term memory loss. When AD is suspected, the diagnosis is usually confirmed with tests that evaluate behaviour and thinking abilities, often followed by a brain scan if available; however, examination of brain tissue is required for a definitive diagnosis. As the disease advances, symptoms can include confusion, irritability, aggression, mood swings, trouble with language, and long-term memory loss. As the person’s condition declines they often withdraw from family and society.

DIFFERENCES BETWEEN ALZEHEIMER AND SENILE DEMENTIA
Alzheimer’s disease (AD) is the most common form of dementia among older people. Dementia is a brain disorder that seriously affects a person’s ability to carry out daily activities.
AD begins slowly. It first involves the parts of the brain that control thought, memory and language. People with AD may have trouble remembering things that happened recently or names of people they know. A related problem, mild cognitive impairment (MCI), causes more memory problems than normal for people of the same age. Many, but not all, people with MCI will develop AD.
Dementia is a broad category of brain diseases that cause long term loss of the ability to think and reason clearly that is severe enough to affect a person’s daily functioning. For the diagnosis to be present it must be a change from previous baseline mental function.Dementia becomes more common with age. While only 3% of people between the ages of 65–74 have dementia, 47% of people over the age of 85 have some form of dementia. As more people are living longer, dementia is becoming more common. Dementia is not a specific disease. It’s an overall term that describes a wide range of symptoms associated with a decline in memory or other thinking skills severe enough to reduce a person’s ability to perform everyday activities. Alzheimer’s disease accounts for 60 to 80 percent of cases. Vascular dementia, which occurs after a stroke, is the second most common dementia type. But there are many other conditions that can cause symptoms of dementia, including some that are reversible, such as thyroid problems and vitamin deficiencies.

REFERENCES
1. Berchtold NC, Cotman CW. Evolution in the Conceptualization of Dementia and Alzheimer’s Disease: Greco-Roman Period to the 1960s. Neurobiology of Aging. 1998;19(3):173–89. doi:10.1016/S0197-4580(98)00052-9. PMID 9661992.
2. Brookmeyer R, Gray S, Kawas C. Projections of Alzheimer’s Disease in the United States and the Public Health Impact of Delaying Disease Onset. American Journal of Public Health. 1998;88(9):1337–42. doi:10.2105/AJPH.88.9.1337. PMID 9736873.
3. 2006 prevalence estimate:
 Brookmeyer R, Johnson E, Ziegler-Graham K, Arrighi HM. Forecasting the global burden of Alzheimer’s disease. Alzheimer’s & Dementia. 2007 [Retrieved 18 June 2008];3(3):186–91. doi:10.1016/j.jalz.2007.04.381. PMID 19595937.
 World population prospects: the 2006 revision, highlights [PDF]. 2007 [Retrieved 27 August 2008].
4. “What is Alzheimer’s disease?”. Alzheimers.org.uk. August 2007. Retrieved 21 February 2008.
5. Waldemar G, Dubois B, Emre M, Georges J, McKeith IG, Rossor M, Scheltens P, Tariska P, Winblad B. Recommendations for the Diagnosis and Management of Alzheimer’s Disease and Other Disorders Associated with Dementia: EFNS Guideline. European Journal of Neurology. 2007;14(1):e1–26. doi:10.1111/j.1468-1331.2006.01605.x. PMID 17222085.
6. “Alzheimer’s diagnosis of AD”. Alzheimer’s Research Trust. Retrieved 29 February 2008.

ADOLESCENT PREGNANCY


ADOLESCENT PREGNANCY

INTRODUCTION
Adolescent or Teenage pregnancy is pregnancy in human females under the age of 20 at the time that the pregnancy ends. A pregnancy can take place in a pubertal female before menarche (the first menstrual period), which signals the possibility of fertility, but usually occurs after menarche. In well-nourished girls, menarche usually takes place around the age of 12 or 13.
A teenager, or teen, is a young person whose age falls within the range from thirteen through nineteen. They are called teenagers because their age number ends in “teen”. Someone aged 18 or 19 is also considered a young adult. Usage by ordinary people varies, and also varies in different societies. Most societies traditionally had a formal ceremony to mark the change from childhood to adulthood. During puberty, rapid mental and physical development occurs. Adolescence is the name for this transition period from childhood to adulthood.
CAUSES OF TEENAGE PREGNANCY
General
In some societies in the world including Nigeria, early marriage and traditional gender roles are important factors in the rate of teenage pregnancy. The average marriage age differs by states, and states where teenage marriages are common experience higher levels of teenage pregnancies. In katsina state, early marriage and pregnancy is more common in traditional rural communities than cities.[18] The lack of education on safe sex, whether it is from parents, schools, or otherwise, is a cause of teenage pregnancy. Many teenagers are not taught about methods of birth control and how to deal with peers who pressure them into having sex before they are ready. Many pregnant teenagers do not have any cognition of the central facts of sexuality.
Following are some of the contributing factors or causes of Adolescent pregnancy
1. Lack of Parental Guidance: Most people evade their children from talking about sex. In some cases, they provide false information regarding sex and discourage their children to participate in any informative discussion about sex. In some cases, teenage mothers are not well educated about sex before getting pregnant
2. Adolescent Sexual Behavior: Among the adolescents, peer pressure is a major factor that encourages the teenage boys and girls to indulge in sexual activities.
3. Inadequate Knowledge about Safe Sex: Most adolescents are unaware of safe sex. They probably have no access to the traditional methods of preventing pregnancy.
4. Exploitation by Older Men: This is another major factor that contributes to pregnancy among the teenagers. Those girls who date older men are more likely to become pregnant before they attain womanhood. Rape, sexual exploitations etc. also takes place that leads to unwanted pregnancy among teenage girls.

5. Socio Economic Factors: Teenage girls who belong to the poor families are more likely to become pregnant. Researchers have found that even in the developed countries teenage pregnancy occurs most commonly among the deprived sections.
6. Lack of supervision: Lack of supervision before teens are ready for independence is one of the causes of teenage pregnancy. Adolescents push boundaries. Look, I know it is easier to let your kid go hang at the mall or wander around an outside shopping area than it is to lay down the rules and stick by them. But if they aren’t at the mall for something specific, they have no business being there.
Knowing where your teens are going and whom they are with is basic Parenting 101. If you don’t know the kids they are hanging out with, get to know them. Allow your teen to have friends over; then make sure you are checking on them regularly down in that basement!
7. Low self-esteem: Low self-esteem is among the causes of teen pregnancy. Children who are not shown love and affection from parents will seek it out with their peer group. Many adolescents report feeling pressured by their peers to have sex before they are ready.
8. Families with two parents: Families with two parents in the home have a lower incidence of teen pregnancies. However, even as a single parent, you can still extend the love, affection, and care your child needs. As a single parent you have less time for yourself, but your child needs a positive role model.
9. Role of drug and alcohol use: Inhibition-reducing drugs and alcohol may possibly encourage unintended sexual activity. If so, it is unknown if the drugs themselves directly influence teenagers to engage in riskier behavior, or whether teenagers who engage in drug use are more likely to engage in sex. Correlation does not imply causation. The drugs with the strongest evidence linking them to teenage pregnancy are alcohol, cannabis, “ecstasy” and other substituted amphetamines. The drugs with the least evidence to support a link to early pregnancy are opioids, such as heroin, morphine, and oxycodone, of which a well-known effect is the significant reduction of libido – it appears that teenage opioid users have significantly reduced rates of conception compared to their non-using, and alcohol, “ecstasy”, cannabis, and amphetamine using peers.
10. Lack of contraception: Adolescents may lack knowledge of, or access to, conventional methods of preventing pregnancy, as they may be too embarrassed or frightened to seek such information. Contraception for teenagers presents a huge challenge for the clinician
According to The Encyclopedia of Women’s Health, published in 2004, there has been an increased effort to provide contraception to adolescents via family planning services and school-based health, such as HIV prevention education.