2,152 research outputs found

    Ageing, depression, anxiety, social support and the diurnal rhythm and awakening response of salivary cortisol

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    The present study compared the cortisol awakening response and diurnal rhythm in 24 young healthy students and 48 community-dwelling older adults. The associations with diurnal cortisol and depression, anxiety and social support were also examined in relation to age. Salivary cortisol was measured over the course of one day: immediately upon awakening, 30 min later, and then 3 h, 6 h, 9 h and 12 h post-awakening. Participants completed a questionnaire measuring symptoms of anxiety and depression and social support was assessed. Older adults exhibited a significantly reduced awakening response, overall cortisol levels, area under the curve (AUC) and diurnal slopes than younger adults, resulting in a flatter diurnal rhythm. Younger adults with higher depression scores had significantly higher overall cortisol and higher levels upon awakening and 30 min post-awakening. In the younger adults, anxiety and depression correlated positively with AUC and the cortisol awakening response (CAR). Older adults with lower social support had a reduced AUC where younger adults with lower social support displayed a larger AUC. These findings suggest that the diurnal rhythm and awakening response of salivary cortisol are significantly reduced in older adults and the associations between anxiety, depression and social support and diurnal cortisol vary with age.\ud \u

    Blunted cardiac reactions to acute psychological stress predict symptoms of depression five years later: Evidence from a large community study

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    We recently reported a cross-sectional negative relationship between cardiovascular reactivity and depressive symptoms. The present analyses examined the prospective association between reactivity and symptoms of depression five years later. At the earlier time point depressive symptoms, using the Hospital Anxiety and Depression Scale (HADS), and cardiovascular reactions to a standard mental stress were measured in 1608 adults comprising three distinct age cohorts: 24-, 44-, and 63-year olds. Depression was re-assessed using the HADS five years later. Heart rate reactions to acute psychological stress were negatively associated with subsequent depressive symptoms; the lower the reactivity the higher the depression scores. This association withstood adjustment for symptom scores at the earlier time point, and for socio-demographic factors and medication status. The mechanisms underlying this prospective relationship remain to be determined

    Selected factors affecting the matabolism of xanthophyll in chickens

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    Consumer demands for chickens with deep yellow skin color and for eggs with moderately yellow yolks have been evident for many years. The degree of pigmentation desired varies considerably according to locations throughout the United States and the world. The use of egg yolks with deep yellow color for specialized foods such as noodles has made the production of such eggs an im-portant part of the poultry industry. Pigmentation is often used in consumer appeal as an attempt to halt the decline in per capita egg consumption and to increase the consumption of broilers. There are problems involved in the production of highly pigmented poultry products. With the advent of high energy-low fiber feeds for both broilers and layers, there has been an interest in the reduction of certain high fiber containing ingredients which may be high in xanthophyll, and, in certain geographical areas, an interest in the use of larger amounts of low xanthophyll containing grains. One species of coccidia, Eimeria maxima, while having little effect on mortality in chickens, is especially troublesome due to its depigmenting effect. The main emphasis in the control of coccidiosis with coccidiostats has been against more pathogenic species of Eimeria than against E. maxima. Therefore, depigmentation continues to be a problem in the production of broilers. While the chicken has no known nutritional or physiological requirements for the xanthophyll pigments, nor can it synthesize these pigments within its body, a greater understanding of factors influencing xanthophyll metabolism would be highly beneficial to the poultry industry. The objectives of the research reported herein were; (1) To study the effects of selected feedstuffs and non-nutritive additives upon xanthophyll metabolism, upon skin and shank pigmentation of young chicks, live and dressed broilers and roasters, and deposition and loss of pigmentation of hens during production. (2) To study the effect of feed intake and environmental temperature upon pigmentation and blood xanthophyll levels of chicks. (3) To study the effects of coccidia upon xanthophyll metabolism

    The Curriculum of Capitalism: Schooled to Profit or Schooled to Educate

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    Utilizing a critical pragmatist framework for analysis of the United States public school education, the research suggests the United States public education system perpetuates a curriculum of Capitalism linking with democracy; yet social Capitalism remains remarkably undemocratic as the experience of race, class, and gender contradict the curriculum of public schools. The consequence of these contradictions is perpetuation of racist or sexist stereotypes, a distinct class system delineated by financial, educational, and techno-wealth, a heightened if not profound sense that the American ideal is no longer within reach or a political sham. In sharp contrast to conservative theories of education and the move to standardize education, progressive educators do not believe in disassociating classroom experience from the sum of the accumulated experience of the individual. The research utilizes a number of tools of curriculum theorists including the incorporation of biographical material of Du Bois, Dewey, Lessing, Marcuse, and Feyerabend as the primary method for investigation

    Life events and acute cardiovascular reactions to mental stress: a cohort study

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    Objective: This study addressed the issue of whether frequent exposure to life events is associated with aggravation or blunting of cardiovascular reactions to acute mental stress. Methods: In a substantial cohort of 585 healthy young adults, systolic and diastolic blood pressure and pulse rate were recorded at rest and in response to a mental arithmetic stress task. Participants indicated, from a list of 50 events, those they had experienced in the last year. Results: There was an overall association between life events and blunted cardiovascular reactivity that was driven by variations in the frequency of exposure to desirable events. The total number of events and the number of personal events were negatively associated with systolic blood pressure and pulse rate reactions to acute stress, whereas the number of work-related events was negatively associated with diastolic blood pressure and pulse rate reactivity. The negative association between total events and systolic blood pressure reactivity was stronger for women than men, whereas men exposed to frequent undesirable events showed enhanced diastolic blood pressure reactivity. The blunting of pulse rate reactivity associated with frequent personal life events was evident particularly for those who had a relatively large number of close friends. Conclusions: The nature and extent of the association between life events exposure and stress reactivity in young adults depends on the valence of the events together with the sex of the individual and their social network size

    The association between life events, social support, and antibody status following thymus-dependent and thymus-independent vaccinations in healthy young adults

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    This study determined whether stressful life events and social support were related to antibody status following both thymus-dependent and thymus-independent vaccinations. Life events in the previous year and customary social support were measured in 57 healthy students at baseline. Antibody status was also assessed at baseline and at five weeks and five months following vaccination with the trivalent influenza vaccine and the meningococcal A+C polysaccharide vaccine. Taking into account baseline antibody titre, high life events scores prior to vaccination were associated with lower responses to the B/Shangdong influenza strain at both five weeks and five months and meningococcal C at five weeks. Life events scores were not associated with response to the other two influenza viral strains nor response to meningococcal A. Those with high social support scores had stronger 5-week and 5-month antibody responses to the A/Panama influenza strain, but not to any of the other strains. These associations could not be accounted for by demographic or health behaviour factors, and also emerged from analyses comparing those who exhibited a four-fold increase in antibody titre from baseline with those who did not. Life events and social support were related to antibody status following influenza vaccination in distinctive ways that may be partly determined by vaccine novelty and prior naturalistic exposure. Life events also predicted poor antibody response to meningococcal C polysaccharide vaccination after previous meningococcal C conjugate vaccination. Neither psychosocial factor was associated with response to primary meningococcal A polysaccharide vaccination

    Hawking radiation, Unruh radiation and the equivalence principle

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    We compare the response function of an Unruh-DeWitt detector for different space-times and different vacua and show that there is a {\it detailed} violation of the equivalence principle. In particular comparing the response of an accelerating detector to a detector at rest in a Schwarzschild space-time we find that both detectors register thermal radiation, but for a given, equivalent acceleration the fixed detector in the Schwarzschild space-time measures a higher temperature. This allows one to locally distinguish the two cases. As one approaches the horizon the two temperatures have the same limit so that the equivalence principle is restored at the horizon.Comment: 9 pages. Added references and added discussion. To be published in PR
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