516 research outputs found
Saturation of nuclear matter and short-range correlations
A fully self-consistent treatment of short-range correlations in nuclear
matter is presented. Different implementations of the determination of the
nucleon spectral functions for different interactions are shown to be
consistent with each other. The resulting saturation densities are closer to
the empirical result when compared with (continuous-choice)
Brueckner-Hartree-Fock values. Arguments for the dominance of short-range
correlations in determining the nuclear-matter saturation density are
presented. A further survey of the role of long-range correlations suggests
that the inclusion of pionic contributions to ring diagrams in nuclear matter
leads to higher saturation densities than empirically observed. A possible
resolution of the nuclear-matter saturation problem is suggested.Comment: 5 pages, 1 figure, to be published in Phys.Rev.Let
Fitness Correlates Of Song Repertoire Size In Free-Living Song Sparrows (Melospiza Melodia)
Models of sexual selection propose that exaggerated secondary sexual ornaments indicate a male\u27s own fitness and the fitness of his offspring. These hypotheses have rarely been thoroughly tested in free-living individuals because overall fitness, as opposed to fitness components, is difficult to measure. We used 20 years of data from song sparrows ( Melospiza melodia) inhabiting Mandarte Island, British Columbia, Canada, to test whether a male\u27s song repertoire size, a secondary sexual trait, predicted overall measures of male or offspring fitness. Males with larger song repertoires contributed more independent and recruited offspring, and independent and recruited grandoffspring, to Mandarte\u27s population. This was because these males lived longer and reared a greater proportion of hatched chicks to independence from parental care, not because females mated to males with larger repertoires laid or hatched more eggs. Furthermore, independent offspring of males with larger repertoires were more likely to recruit and then to leave more grandoffspring than were offspring of males with small repertoires. Although we cannot distinguish whether observed fitness variation reflected genetic or environmental effects on males or their offspring, these data suggest that female song sparrows would gain immediate and intergenerational fitness benefits by pairing with males with large song repertoires
Feasibility of TEE-guided stroke risk assessment in atrial fibrillation—background, aims, design and baseline data of the TIARA pilot study
Contains fulltext :
97916.pdf (publisher's version ) (Open Access)BACKGROUND: Antithrombotic management in atrial fibrillation (AF) is currently based on clinical characteristics, despite evidence of potential fine-tuning with transoesophageal echocardiography (TEE). This open, randomised, multicentre study addresses the hypothesis that a comprehensive strategy of TEE-based aspirin treatment in AF patients is feasible and safe. METHODS: Between 2005 and 2009, ten large hospitals in the Netherlands enrolled AF patients with a moderate risk of stroke. Patients without thrombogenic TEE characteristics were randomised to aspirin or vitamin K antagonists (VKA). The primary objective is to show that TEE-based aspirin treatment is safe compared with VKA therapy. The secondary objective tests feasibility of TEE as a tool to detect echocardiographic features of high stroke risk. This report compares randomised to non-randomised patients and describes the feasibility of a TEE-based approach. RESULTS: In total, 310 patients were included. Sixty-nine patients were not randomised because of non-visualisation (n = 6) or TEE risk factors (n = 63). Compared with non-randomised patients, randomised patients (n = 241) were younger (65 +/- 11 vs. 69 +/- 9 years, p = 0.004), had less coronary artery disease (9 vs. 20%, p = 0.018), previous TIA (1.7 vs. 7.2%, p = 0.029), AF during TEE (25 vs. 54%, p < 0.001), mitral incompetence (55 vs. 70%, p = 0.038), VKA use (69 vs. 82%, p = 0.032), had a lower mean CHADS(2) score (1.2 +/- 0.6 vs. 1.6 +/- 1.0, p = 0.004), and left ventricular ejection fraction (59 +/- 8 vs. 56 +/- 8%, p = 0.016). CONCLUSIONS: This study shows that a TEE-based approach for fine-tuning stroke risk in AF patients with a moderate risk for stroke is feasible. Follow-up data will address the safety of this TEE-based approach
A Novel Method for Teaching the First Instances of Simple Discrimination to Nonverbal Children with Autism in a Laboratory Environment
A nomenclature for restriction enzymes, DNA methyltransferases, homing endonucleases and their genes
A nomenclature is described for restriction endonucleases, DNA methyltransferases, homing endonucleases and related genes and gene products. It provides explicit categories for the many different Type II enzymes now identified and provides a system for naming the putative genes found by sequence analysis of microbial genomes
Atypical development of the executive attention network in children with chromosome 22q11.2 deletion syndrome
Impairment in the executive control of attention has been found in youth with chromosome 22q11.2 deletion syndrome (22q11.2DS). However, how this impairment is modified by other factors, particularly age, is unknown. Forty-six typically developing and 53 children with 22q11.2DS were tested with the attention networks task (ANT) in this cross-sectional study. We used logarithmic transform and linear modeling to assess age effects on the executive index of the ANT. Mixed modeling accounted for between subject variability, age, handedness, catecholamine-O-transferase (COMT; codon 158) genotype, and gender on performance for all experimental conditions (cue × flanker) and their two-level interactions. Children with 22q11.2DS showed a relative, age-dependent executive index impairment but not orienting or alerting network index impairments. In factorial analysis, age was a major predictor of overall performance. There was a significant effect of the 22q11.2DS on overall performance. Of note, children with 22q11.2DS are specifically vulnerable to incongruent flanker interference, especially at younger ages. We did not find an overall effect of COMT genotype or handedness. Children with 22q11.2DS demonstrated age-related impairment in the executive control of attention. Future investigation will likely reveal that there are different developmental trajectories of executive attentional function likely related to the development of schizophrenia in 22q11.2DS
A preliminary fishery quality index for Portuguese streams
There is a need to quantify the multivariate quality of a recreational fishery at the site scale to
better communicate the relative quality among sites to the public and anglers. Borrowing on the general
approach of multimetric indices of biotic integrity (IBIs), we developed fishery quality indices (FQIs) from
species quality indices (SQIs) based on measures of fish abundance and size structure for northern and central
Portuguese streams. Our FQIs showed regional patterns indicating a range in fishery quality. Higher coldwater
FQI scores were mostly found in the northwestern (Minho and Lima), northeastern Douro, and northern Tagus
basins. Higher warmwater FQI scores occurred in the eastern Tagus basin. The species that contributed the
most to warmwater FQI scores were largemouth bass Micropterus salmoides, pumpkinseed Lepomis
gibbosus, the cyprinid Luciobarbus bocagei, chubs Squalius carolitertii and S. pyrenaicus, and nases
Pseudochondrostoma duriense and P. polylepis. The chubs, nases, and brown trout Salmo trutta contributed
the most to coldwater FQI scores. As expected, our indices were correlated with river size and with
disturbance at the catchment, segment, and site scales. Regression models for separate coldwater and
warmwater FQIs were stronger than those for the individual SQIs and for an all-site FQI. The correlation was
positive between the coldwater FQI and a coldwater IBI but negative between the warmwater FQI and
warmwater IBIs. The proposed FQIs offer a quantitative approach for assessing relative fishery quality among
sites and for making regional assessments given an appropriate study design. The component SQIs and SQI
metrics of the FQIs can be disassociated to determine the population and species characteristics most affected
by various environmental variables
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