568 research outputs found
The Gluonic Field of a Heavy Quark in Conformal Field Theories at Strong Coupling
We determine the gluonic field configuration sourced by a heavy quark
undergoing arbitrary motion in N=4 super-Yang-Mills at strong coupling and
large number of colors. More specifically, we compute the expectation value of
the operator tr[F^2+...] in the presence of such a quark, by means of the
AdS/CFT correspondence. Our results for this observable show that signals
propagate without temporal broadening, just as was found for the expectation
value of the energy density in recent work by Hatta et al. We attempt to shed
some additional light on the origin of this feature, and propose a different
interpretation for its physical significance. As an application of our general
results, we examine when the quark undergoes oscillatory motion,
uniform circular motion, and uniform acceleration. Via the AdS/CFT
correspondence, all of our results are pertinent to any conformal field theory
in 3+1 dimensions with a dual gravity formulation.Comment: 1+38 pages, 16 eps figures; v2: completed affiliation; v3: corrected
typo, version to appear in JHE
Sequential decoupling of negative-energy states in Douglas-Kroll-Hess theory
Here, we review the historical development, current status, and prospects of
Douglas--Kroll--Hess theory as a quantum chemical relativistic electrons-only
theory.Comment: 15 page
An overview of the current status of CMB observations
In this paper we briefly review the current status of the Cosmic Microwave
Background (CMB) observations, summarising the latest results obtained from CMB
experiments, both in intensity and polarization, and the constraints imposed on
the cosmological parameters. We also present a summary of current and future
CMB experiments, with a special focus on the quest for the CMB B-mode
polarization.Comment: Latest CMB results have been included. References added. To appear in
"Highlights of Spanish Astrophysics V", Proceedings of the VIII Scientific
Meeting of the Spanish Astronomical Society (SEA) held in Santander, 7-11
July, 200
Patient-reported outcomes in the aging population of adults with congenital heart disease: results from APPROACH-IS.
The congenital heart disease (CHD) population now comprises an increasing number of older persons in their 6th decade of life and beyond. We cross-sectionally evaluated patient-reported outcomes (PROs) in persons with CHD aged 60 years or older, and contrasted these with PROs of younger patients aged 40-59 years and 18-39 years. Adjusted for demographic and medical characteristics, patients ≥60 years had a lower Physical Component Summary, higher Mental Component Summary, and lower anxiety (Hospital Anxiety and Depression Scale-Anxiety) scores than patients in the two younger categories. For satisfaction with life, older persons had a higher score than patients aged 40-59 years. Registration: ClinicalTrials.gov NCT02150603
The construction of ethnic identity: insights from identity process theory
Ethnicity has received much empirical and theoretical attention in the social sciences. Yet, it has scarcely been explored in terms of its relationship with the motivational principles of identity. Here it is argued that there is much heuristic and predictive value in applying identity process theory (IPT), a socio-psychological model of identity threat, to the substantive literature on ethnicity. The paper explores the potential psychological benefits of ethnic identification. Key theoretical strands from anthropology and sociology, such as the ‘relational self’ in ethnic identification, are discussed in relation to IPT. The intergroup dimension of ethnic identification is explored through the discussion of ethnic 'boundaries'. Finally, the paper discusses the construct of 'hybridization' in relation to social psychology. This paper attempts to reconcile psychological and sociological perspectives on ethnic identification, advocating a multi-methodological approach. Key theoretical points are outlined in the form of testable hypotheses which are open to empirical exploration
A potential nitrergic mechanism of action for indomethacin, but not of other COX inhibitors: relevance to indomethacin-sensitive headaches
Non-steroidal anti-inflammatory drugs (NSAIDs) that act as cyclo-oxygenase (COX) inhibitors are commonly used in the treatment of a range of headache disorders, although their mechanism of action is unclear. Indomethacin is of particular interest given its very special effect in some primary headaches. Here the in vivo technique of intravital microscopy in rats has been utilised as a model of trigeminovascular nociception to study the potential mechanism of action of indomethacin. Dural vascular changes were produced using electrical (neurogenic) dural vasodilation (NDV), calcitonin gene-related peptide (CGRP) induced dural vasodilation and nitric oxide (NO) induced dural vasodilation using NO donors. In each of these settings the effect of intravenously administered indomethacin (5 mg kg−1), naproxen (30 mg kg−1) and ibuprofen (30 mg kg−1) was tested. All of the tested drugs significantly inhibited NDV (between 30 and 52%). Whilst none of them was able to inhibit CGRP-induced dural vasodilation, only indomethacin reduced NO induced dural vasodilation (35 ± 7%, 10 min post administration). We conclude NSAIDs inhibit release of CGRP after NDV without an effect on CGRP directly. Further we describe a differentiating effect of indomethacin inhibiting nitric oxide induced dural vasodilation that is potentially relevant to understanding its unique action in disorders such as paroxysmal hemicrania and hemicrania continua
Education, sense of mastery and mental health: results from a nation wide health monitoring study in Norway
<p>Abstract</p> <p>Background</p> <p>Earlier studies have shown that people with low level of education have increased rates of mental health problems. The aim of the present study is to investigate the association between level of education and psychological distress, and to explore to which extent the association is mediated by sense of mastery, and social variables like social support, negative life events, household income, employment and marital status.</p> <p>Methods</p> <p>The data for the study were obtained from the Level of Living Survey conducted by Statistics Norway in 2002. Data on psychological distress and psychosocial variables were gathered by a self-administered questionnaire, whereas socio-demographic data were based on register statistics. Psychological distress was measured by Hopkins Symptom Checklist 25 items.</p> <p>Results</p> <p>There was a significant association between low level of education and psychological distress in both genders, the association being strongest in women aged 55–67 years. Low level of education was also significantly associated with low sense of mastery, low social support, many negative life events (only in men), low household income and unemployment,. Sense of mastery emerged as a strong mediating variable between level of education and psychological distress, whereas the other variables played a minor role when adjusting for sense of mastery.</p> <p>Conclusion</p> <p>Low sense of mastery seems to account for much of the association between low educational level and psychological distress, and should be an important target in mental health promotion for groups with low level of education.</p
Participant Nonnaiveté and the reproducibility of cognitive psychology
Many argue that there is a reproducibility crisis in psychology. We investigated nine well-known effects from the cognitive psychology literature—three each from the domains of perception/action, memory, and language, respectively—and found that they are highly reproducible. Not only can they be reproduced in online environments, but they also can be reproduced with nonnaïve participants with no reduction of effect size. Apparently, some cognitive tasks are so constraining that they encapsulate behavior from external influences, such as testing situation and prior recent experience with the experiment to yield highly robust effects
Regulation of Progranulin Expression in Human Microglia and Proteolysis of Progranulin by Matrix Metalloproteinase-12 (MMP-12)
Background: The essential role of progranulin (PGRN) as a neurotrophic factor has been demonstrated by the discovery that haploinsufficiency due to GRN gene mutations causes frontotemporal lobar dementia. In addition to neurons, microglia in vivo express PGRN, but little is known about the regulation of PGRN expression by microglia. Goal: In the current study, we examined the regulation of expression and function of PGRN, its proteolytic enzyme macrophage elastase (MMP-12), as well as the inhibitor of PGRN proteolysis, secretory leukocyte protease inhibitor (SLPI), in human CNS cells. Methods: Cultures of primary human microglia and astrocytes were stimulated with the TLR ligands (LPS or poly IC), Th1 cytokines (IL-1/IFNc), or Th2 cytokines (IL-4, IL-13). Results were analyzed by Q-PCR, immunoblotting or ELISA. The roles of MMP-12 and SLPI in PGRN cleavage were also examined. Results: Unstimulated microglia produced nanogram levels of PGRN, and PGRN release from microglia was suppressed by the TLR ligands or IL-1/IFNc, but increased by IL-4 or IL-13. Unexpectedly, while astrocytes stimulated with proinflammatory factors released large amounts of SLPI, none were detected in microglial cultures. We also identified MMP-12 as a PGRN proteolytic enzyme, and SLPI as an inhibitor of MMP-12-induced PGRN proteolysis. Experiments employing PGRN siRNA demonstrated that microglial PGRN was involved in the cytokine and chemokine production following TLR3/4 activation
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