956 research outputs found
Chandra Observation of the Interaction of the Radio Source and Cooling Core in Abell 2063
We present the results of a Chandra observation of the cooling core cluster
Abell 2063. Spectral analysis shows that there is cool gas (2 keV) associated
with the cluster core, which is more than a factor of 2 cooler than the outer
cluster gas (4.1 keV). There also is spectral evidence for a weak cooling flow,
Mdot ~ 20 Msun/yr. The cluster exhibits a complex structure in the center that
consists of several bright knots of emission, a depression in the emission to
the north of the center of the cluster, and a shell of emission surrounding it.
The depression in the X-ray emission is coincident with the position of the
north-eastern radio lobe of the radio source associated with the
cluster-central galaxy. The shell surrounding this region appears to be hotter,
which may be the result of a shock that has been driven into the gas by the
radio source. The power output of the radio source appears to be sufficient to
offset the cooling flow, and heating of the gas through shocks is a possible
explanation of how the energy transfer is established.Comment: Astrophysical Jounal, in press, 26 page with 9 figures, some in
color. Uses AASTEX late
Preferences Toward Gender of Coach and Perceptions of Roles of Basketball Coaches
International Journal of Exercise Science 8(4): 303-317. Framed within role congruity theory this study examined (a) if female collegiate basketball players have a preference toward male or female head basketball coaches, (b) if the gender and enjoyment level of past head coaches influence preferences toward a male or female head coach and/or influence the perceived roles of womenâs basketball head coaches, and (c) if there is a relationship between the perceived roles of womenâs basketball head coaches and female collegiate basketball playersâ preferences toward male or female head coaches. Fifty-nine womenâs basketball players from 10 Division I universities completed a survey that included a consent form, demographic questions, the list of managerial sub roles, and questions regarding preferences, gender, and enjoyment level of past and current coaches. Participants significantly preferred male head coaches compared to female head coaches. A cluster analysis was conducted to group participants into a male coach profile and a female coach profile using the variables of gender of past and current coaches and the gender of coach enjoyed most. Results showed that the male coach profile group preferred male coaches significantly more than the female coach profile group. Because preferences for male coaches still exist, especially with female basketball players who did not have a female high school coach, it is vital that the numbers of female coaches increase, especially at younger age levels
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Failure to regulate: counterproductive recruitment of top-down prefrontal-subcortical circuitry in major depression
Although depressed mood is a normal occurrence in response to adversity in all individuals, what distinguishes those who are vulnerable to major depressive disorder (MDD) is their inability to effectively regulate negative mood when it arises. Investigating the neural underpinnings of adaptive emotion regulation and the extent to which such processes are compromised in MDD may be helpful in understanding the pathophysiology of depression. We report results from a functional magnetic resonance imaging study demonstrating left-lateralized activation in the prefrontal cortex (PFC) when downregulating negative affect in nondepressed individuals, whereas depressed individuals showed bilateral PFC activation. Furthermore, during an effortful affective reappraisal task, nondepressed individuals showed an inverse relationship between activation in left ventrolateral PFC and the amygdala that is mediated by the ventromedial PFC (VMPFC). No such relationship was found for depressed individuals, who instead show a positive association between VMPFC and amygdala. Pupil dilation data suggest that those depressed patients who expend more effort to reappraise negative stimuli are characterized by accentuated activation in the amygdala, insula, and thalamus, whereas nondepressed individuals exhibit the opposite pattern. These findings indicate that a key feature underlying the pathophysiology of major depression is the counterproductive engagement of right prefrontal cortex and the lack of engagement of left lateral-ventromedial prefrontal circuitry important for the downregulation of amygdala responses to negative stimuli
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Amygdala and ventromedial prefrontal cortex are inversely coupled during regulation of negative affect and predict the diurnal pattern of cortisol secretion among older adults
Among younger adults, the ability to willfully regulate negative affect, enabling effective responses to stressful experiences, engages regions of prefrontal cortex (PFC) and the amygdala. Because regions of PFC and the amygdala are known to influence the hypothalamic-pituitary-adrenal axis, here we test whether PFC and amygdala responses during emotion regulation predict the diurnal pattern of salivary cortisol secretion. We also test whether PFC and amygdala regions are engaged during emotion regulation in older (62- to 64-year-old) rather than younger individuals. We measured brain activity using functional magnetic resonance imaging as participants regulated (increased or decreased) their affective responses or attended to negative picture stimuli. We also collected saliva samples for 1 week at home for cortisol assay. Consistent with previous work in younger samples, increasing negative affect resulted in ventral lateral, dorsolateral, and dorsomedial regions of PFC and amygdala activation. In contrast to previous work, decreasing negative affect did not produce the predicted robust pattern of higher PFC and lower amygdala activation. Individuals demonstrating the predicted effect (decrease s attend in the amygdala), however, exhibited higher signal in ventromedial prefrontal cortex (VMPFC) for the same contrast. Furthermore, participants displaying higher VMPFC and lower amygdala signal when decreasing compared with the attention control condition evidenced steeper, more normative declines in cortisol over the course of the day. Individual differences yielded the predicted link between brain function while reducing negative affect in the laboratory and diurnal regulation of endocrine activity in the home environment
Board Committees in Corporate Governance: A CrossâDisciplinary Review and Agenda for the Future
The importance of board committees â specialized subgroups that exist to perform many of the board\u27s most critical functions, such as setting executive compensation, identifying potential board members, and overseeing financial reporting â has grown over time due to increased legal requirements and greater complexity of the environment in which firms operate. This has resulted in a large body of work examining board committees across the accounting, finance, and management disciplines. However, this research has developed rather independently within each discipline, preventing scholars and practitioners from developing a comprehensive understanding of board committees. To address this issue, we conduct a comprehensive review of the literature that: 1) summarizes and synthesizes antecedents and outcomes associated with board committees in publiclyâtraded firms in English common law countries; and 2) offers a critical analysis of existing research, providing recommendations for advancements and new directions in board committee research
Helium Porosity Formation in Vanadium Alloys of V-Ti-Cr, V-W-Zr and V-W-Ta Systems in Comparison with Binary Alloys
Vanadium alloys are considered candidates for use as structural materials of fusion reactors. A large amount of helium will be accumulated in such materials. The presence of helium in the materials may result in gas swelling. This paper presents the results on helium porosity formation researches in VâTiâCr, VâWâZr and VâWâTa alloys obtained by means of TEM. Samples were irradiated by 40 keV ĐĐ”+ ions up to dose of 5 â
1020mâ2 at 923 K. Alloy Vâ4%Tiâ4%Cr has a smallest helium swelling among the ternary alloys and its swelling is significantly lower than swelling of dual VâTi and VâCr alloys. The swelling of the ternary Vâ2%Wâ1%Zr alloy is more than 3 times less than the swelling of vanadium, several times less than that of VâW alloys and slightly lower than the swelling of Vâ Zr alloys. Swelling increases by a factor of 1.5 with increasing of Zr content to 2% in the ternary Vâ2%Wâ1%Zr alloy. Similarly, gas swelling of ternary Vâ2%Wâ1%Ta alloy is significantly lower than that for binary VâW and VâTa alloys. Assumptions are made about the possible mechanisms of the effect of alloying elements in vanadium on helium porosity formation.
Keywords: vanadium alloys, swelling, helium, radiation resistance
Board Committees in Corporate Governance: A Cross-Disciplinary Review and Agenda for the Future
The importance of board committees â specialized subgroups that exist to perform many of the board\u27s most critical functions, such as setting executive compensation, identifying potential board members, and overseeing financial reporting â has grown over time due to increased legal requirements and greater complexity of the environment in which firms operate. This has resulted in a large body of work examining board committees across the accounting, finance, and management disciplines. However, this research has developed rather independently within each discipline, preventing scholars and practitioners from developing a comprehensive understanding of board committees. To address this issue, we conduct a comprehensive review of the literature that: 1) summarizes and synthesizes antecedents and outcomes associated with board committees in publicly-traded firms in English common law countries; and 2) offers a critical analysis of existing research, providing recommendations for advancements and new directions in board committee research
The Marco Gonzalez Maya site, Ambergris Caye, Belize: assessing the impact of human activities by examining diachronic processes at the local scale
Research at the Maya archaeological site of Marco Gonzalez on Ambergris Caye in Belize is socio-ecological because human activities have been a factor in the formation and fluctuation of the local marine and terrestrial environments over time. The site is one of many on Belize's coast and cayes that exhibit anomalous vegetation and dark-coloured soils. These soils, although sought for cultivation, are not typical 'Amazonian Dark Earths' but instead are distinctive to the weathering of carbonate-rich anthropogenic deposits. We tentatively term these location-specific soils as Maya Dark Earths. Our research seeks to quantify the role of human activities in long-term environmental change and to develop strategies, specifically Life Cycle Assessment (LCA), that can be applied to environmental impact modelling today
Trait-Like Brain Activity during Adolescence Predicts Anxious Temperament in Primates
Early theorists (Freud and Darwin) speculated that extremely shy children, or those with anxious temperament, were likely to have anxiety problems as adults. More recent studies demonstrate that these children have heightened responses to potentially threatening situations reacting with intense defensive responses that are characterized by behavioral inhibition (BI) (inhibited motor behavior and decreased vocalizations) and physiological arousal. Confirming the earlier impressions, data now demonstrate that children with this disposition are at increased risk to develop anxiety, depression, and comorbid substance abuse. Additional key features of anxious temperament are that it appears at a young age, it is a stable characteristic of individuals, and even in non-threatening environments it is associated with increased psychic anxiety and somatic tension. To understand the neural underpinnings of anxious temperament, we performed imaging studies with 18-fluoro-deoxyglucose (FDG) high-resolution Positron Emission Tomography (PET) in young rhesus monkeys. Rhesus monkeys were used because they provide a well validated model of anxious temperament for studies that cannot be performed in human children. Imaging the same animal in stressful and secure contexts, we examined the relation between regional metabolic brain activity and a trait-like measure of anxious temperament that encompasses measures of BI and pituitary-adrenal reactivity. Regardless of context, results demonstrated a trait-like pattern of brain activity (amygdala, bed nucleus of stria terminalis, hippocampus, and periaqueductal gray) that is predictive of individual phenotypic differences. Importantly, individuals with extreme anxious temperament also displayed increased activity of this circuit when assessed in the security of their home environment. These findings suggest that increased activity of this circuit early in life mediates the childhood temperamental risk to develop anxiety and depression. In addition, the findings provide an explanation for why individuals with anxious temperament have difficulty relaxing in environments that others perceive as non-stressful
Depth concentrations of deuterium ions implanted into some pure metals and alloys
Pure metals (Cu, Ti, Zr, V, Pd) and diluted Pd-alloys (Pd-Ag, Pd-Pt, Pd-Ru,
Pd-Rh) were implanted by 25 keV deuterium ions at fluences in the range
(1.2{\div}2.3)x1022 D+/m2. The post-treatment depth distributions of deuterium
ions were measured 10 days and three months after the implantation using
Elastic Recoil Detection Analysis (ERDA) and Rutherford Backscattering (RBS).
Comparison of the obtained results allowed to make conclusions about relative
stability of deuterium and hydrogen gases in pure metals and diluted Pd alloys.
Very high diffusion rates of implanted deuterium ions from V and Pd pure metals
and Pd alloys were observed. Small-angle X-ray scattering revealed formation of
nanosized defects in implanted corundum and titanium.Comment: 12 pages, 9 figure
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