3,373 research outputs found
Double Sivers effect asymmetries and their impact on transversity measurements at RHIC
We study double transverse spin asymmetries in the Drell-Yan process at
measured transverse momentum of the lepton pair. Contrary to what a collinear
factorization approach would suggest, a nonzero double transverse spin
asymmetry in the laboratory frame a priori does not imply nonzero transversity.
TMD effects, such as the double Sivers effect, in principle form a background.
Using the current knowledge of the relevant TMDs we estimate their contribution
in the laboratory frame for Drell-Yan and W production at RHIC and point out a
cross check asymmetry measurement to bound the TMD contributions. We also
comment on the transverse momentum integrated asymmetries that only receive
power suppressed background contributions.Comment: 12 pages, 11 eps figures, minor changes, matches the published
versio
Genetics in heart failure:where are we headed?
Heart failure is a complex disease with many precipitating factors. Novel insights into the genetic background of heart failure have boosted new areas of research that gave rise to the concept of genetic predisposition for heart failure. Various genetic defects and variances have been identified and subsequently linked to the onset of or progression to heart failure. Nevertheless, our understanding of the genetic basis for heart failure is incomplete because we lack knowledge of the functionality of genetic variances. We also do not understand the impact of genetic variances in noncoding DNA because of logistic problems in performing whole-genome scans and difficulties in statistical evaluation of large amounts of data generated by the genetic boom. It is expected that in the future we will be able to overcome these problems and apply the knowledge gained by genetic analyses to target and optimize treatment.</p
Paediatric Residents and Fellows Ethics (PERFEct) survey: Perceptions of European trainees regarding ethical dilemmas
With an increasingly complex healthcare environment, ethics is becoming a more critical part of medical education. We aimed to explore European paediatric trainees’ experiences of facing ethical dilemmas and their medical ethics education whilst assessing their perceptions of ethical dilemmas in current and future practice. The Young Sections of the European Academy of Paediatrics and European Society of Paediatric and Neonatal Intensive Care developed an explorative online survey covering demographics, ethical dilemmas faced and ethics training. The survey was made available in nine languages from November 2019 to January 2020 via newsletters and social media. Participants (n = 253) from 22 countries, predominantly female (82%) and residents (70%), with a median age of 29-years, completed the survey. The majority (58%) faced ethical dilemmas monthly or more frequently. Most ethics training was received by ethics lectures in medical school (81%) and on the job (60%). A disagreement between the healthcare team and patient/family was the most frequently faced moral dilemma (45%); the second was withholding/withdrawing life-prolonging measures (33%). The latter was considered the most challenging dilemma to resolve (50%). Respondents reported that ethical issues are not sufficiently addressed during their training and wished for more case-based teaching. Many have been personally affected by moral dilemmas, especially regarding withholding/withdrawing life-prolonging measures, and often felt inadequately supported. Conclusion: Paediatric trainees face many moral issues in daily practice and consider that training about managing current and future ethical dilemmas should be improved, such as by the provision of a core European paediatric ethics curriculum. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00431-021-04231-8
Social welfare and profit maximization from revealed preferences
Consider the seller's problem of finding optimal prices for her
(divisible) goods when faced with a set of consumers, given that she can
only observe their purchased bundles at posted prices, i.e., revealed
preferences. We study both social welfare and profit maximization with revealed
preferences. Although social welfare maximization is a seemingly non-convex
optimization problem in prices, we show that (i) it can be reduced to a dual
convex optimization problem in prices, and (ii) the revealed preferences can be
interpreted as supergradients of the concave conjugate of valuation, with which
subgradients of the dual function can be computed. We thereby obtain a simple
subgradient-based algorithm for strongly concave valuations and convex cost,
with query complexity , where is the additive
difference between the social welfare induced by our algorithm and the optimum
social welfare. We also study social welfare maximization under the online
setting, specifically the random permutation model, where consumers arrive
one-by-one in a random order. For the case where consumer valuations can be
arbitrary continuous functions, we propose a price posting mechanism that
achieves an expected social welfare up to an additive factor of
from the maximum social welfare. Finally, for profit maximization (which may be
non-convex in simple cases), we give nearly matching upper and lower bounds on
the query complexity for separable valuations and cost (i.e., each good can be
treated independently)
Long-term social restrictions and lack of work activities during the COVID-19 pandemic:Impact on the daily lives of people with intellectual disabilities
Purpose: Lockdowns due to the Covid-19 pandemic may have had a disproportionate impact on the daily lives of people with intellectual disabilities. Many of them had to deal with limited social contacts for an extended period. This study explores in depth how people with intellectual disabilities in the Netherlands experienced their daily lives, in particular due to lack of access to regular work activities. Materials and methods: Eight participants with intellectual disabilities were interviewed. Interpretative Phenomenological Analysis (IPA) was employed in conducting and analysing interviews. Results and conclusions: Analysis yielded three overarching themes that are conceptually linked. Participants experienced a prolonged lack of social connections that resulted in experiences of social isolation and feelings of loneliness. This led to different kinds of struggles: either internal struggles involving negative thoughts or depressive feelings, or a perceived threat to their autonomous position in society. Meanwhile participants had to sustain their sense of self-worth in the absence of work activities. The findings emphasise the importance of social opportunities through the access to work activities for people with intellectual disabilities. Interventions are suggested to help reverse the increased social inequalities and enhance rehabilitation via work activities for people with intellectual disabilities. Implications for rehabilitation: More awareness may be raised among authorities, employers and the general public about the significant value people with intellectual disabilities attribute to meaningful social connections, in particular through work activities. Also, more awareness may be raised about the potential adverse effects of the loss of work activities and social connections on the quality of life of people with intellectual disabilities. Providing social support to others may help people with intellectual disabilities to construct social valued roles, either in or outside the work situation. Professionals and employers can support people with intellectual disabilities to find opportunities to provide social support to others. It is important to invest in sustainable and innovative post-pandemic community participation initiatives and particularly in accessible post-pandemic employment support, for example by organising paid in-company training placements. It is essential that professionals support people with intellectual disabilities to enhance their sources of resilience and coping strategies, that may have diminished as a result of the pandemic
Improved stability regions for ground states of the extended Hubbard model
The ground state phase diagram of the extended Hubbard model containing
nearest and next-to-nearest neighbor interactions is investigated in the
thermodynamic limit using an exact method. It is found that taking into account
local correlations and adding next-to-nearest neighbor interactions both have
significant effects on the position of the phase boundaries. Improved stability
domains for the -pairing state and for the fully saturated ferromagnetic
state at half filling have been constructed. The results show that these states
are the ground states for model Hamiltonians with realistic values of the
interaction parameters.Comment: 21 pages (10 figures are included) Revtex, revised version. To be
published in Phys. Rev. B. E-mail: [email protected]
Edge detection versus densitometry in the quantitative assessment of stenosis phantoms: an in vivo comparison in procine coronary arteries
The aim of this study was the in vivo validation and comparison of the geometric and densitometric technique of a computer-assisted automatic quantitative angiographic system (CAAS system). In six Landrace Yorkshire pigs (45 to 55 kg), precision-drilled phantoms with a circular lumen of 0.5, 0.7, 1.0, 1.4, and 1.9 mm were percutaneously introduced into the left anterior descending or left circumflex coronary artery. Twenty-eight coronary angiograms obtained with the phantom in a wedged intracoronary position could be quantitatively analyzed. Minimal lumen diameter, minimal cross-sectional area, percent diameter stenosis, and cross-sectional area stenosis were automatically measured with both the geometric and densitometric technique and were compared with the known phantom dimensions. When minimal lumen diameter was measured using the geometric approach, a nonsignificant underestimation of the phantom size was observed, with a mean difference of -0.06 +/- 0.14 mm. The larger mean difference observed with videodensitometry (-0.11 +/- 0.20 mm) was the result of the failure of the technique to differentiate the low lumen videodensities of two phantoms of smaller size (0.5 and 0.7 mm) from a dense background. Percent cross-sectional area stenosis measured with the two techniques showed a good correlation with the corresponding phantom measurements (mean difference between percent cross-sectional area stenosis calculated from the quantitative angiographic measurements and the corresponding phantom dimensions was equal to 2 +/- 6% for both techniques, correlation coefficient = 0.93 with both techniques, SEE = 5% with the geometric technique and 6% with the densitometric approach).(ABSTRACT TRUNCATED AT 250 WORDS
Ovariectomy-induced depressive-like behavior and brain glucose metabolism changes in female rats are not affected by chronic mild stress
The increased incidence of depression in women going through peri-menopause suggests that fluctuations in estrogen levels may increase the risk of developing depression. Nonetheless, this psychiatric disorder is likely to be multifactorial and consequently an additional trigger may be needed to induce depression in this population. Stress could be such a trigger. We therefore investigated the effect of ovarian estrogen depletion and chronic mild stress (CMS) on depressive-like behavior and brain metabolism in female rats. Approximately 2 and 9 weeks after estrogen depletion by ovariectomy, behavioral changes were assessed in the open-field test and the forced swim test, and brain metabolism was measured with [18F]FDG PET imaging. A subset of animals was subjected to a 6-weeks CMS protocol starting 17 days after ovariectomy. Short-term estrogen depletion had a significant effect on brain metabolism in subcortical areas, but not on behavior. Differences in depressive-like behavior were only found after prolonged estrogen depletion, leading to an increased immobility time in the forced swim test. Prolonged estrogen depletion also resulted in an increase in glucose metabolism in frontal cortical areas and hippocampus, whereas a decrease glucose metabolism was found in temporal cortical areas, hypothalamus and brainstem. Neither short-term nor prolonged estrogen depletion caused anxiety-like behavior. Changes in body weight, behavior and brain glucose metabolism were not significantly affected by CMS. In conclusion, ovarian estrogen depletion resulted in changes in brain metabolism and depressive-like behavior, but these changes were not enhanced by CMS
Effects of the mGluR2/3 agonist LY379268 on ketamine-evoked behaviours and neurochemical changes in the dentate gyrus of the rat
One of the functions of group 11 metabotropic glutamate receptors (mGluR2/3) is to modulate glutamate release. Thus, targeting mGluR2/3s might be a novel treatment for several psychiatric disorders associated with inappropriate glutamatergic neurotransmission, such as schizophrenia. In an effort to evaluate the antipsychotic properties of LY379268; a potent and selective mGluR2/3 agonist, we examined its effect on ketamine-evoked hyperlocomotion and sensorimotor gating deficit (PPI) in rats, an animal model of schizophrenia. We also measured the ex vivo tissue level of glutamate (Glu), dopamine (DA) and serotonin (5-HT) as well as the DA metabolites DOPAC and the major 5-HT metabolite HIAA to determine the neurochemical effects of ketamine (12 mg/kg) and LY379268 (1 mg/kg) in the dentate gyrus (DG). While LY379268 (1-3 mg/kg) reduced ketamine-evoked hyperlocomotion (12 mg/kg), it could not restore ketamine-evoked PPI deficits (4-12 mg/kg). In the DG we found that ketamine decreased Glu and DA levels, as well as HIAA/5-HT turnover, and that LY379268 could prevent ketamine effects on Glu level but not on monoamine transmission. These results may indicate that the inability of LY379268 to reverse PPI deficits is attributable to its lack of effect on ketamine-induced changes in monoamine transmission, but that LY379268 can prevent ketamine-evoked changes in glutamate, which is sufficient to block hyperlocomotion. In addition to the partial effectiveness of LY379268 in the ketamine model of schizophrenia, we observed a dual effect of LY379268 on anxious states, whereby a low dose of this compound (1 mg/kg) produced anxiolytic effects, while a higher dose (3 mg/kg) appeared to be anxiogenic. Additional work is needed to address a possible role of LY379268 in schizophrenia and anxiety treatment. (c) 2006 Elsevier Inc. All rights reserved
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