Modern meson--exchange potential and superfluid neutron star crust matter

In this work we study properties of neutron star crusts, where matter is expected to consist of nuclei surrounded by superfluid neutrons and a homogeneous background of relativistic electrons. The nuclei are disposed in a Coulomb lattice, and it is believed that the structure of the lattice influences considerably the specific heat of the neutronic matter inside the crust of a neutron star. Using a modern meson--exchange potential in the framework of a local--density approximation we calculate the neutronic specific heat accounting for various shapes of the Coulomb lattice, from spherical to non--spherical nuclear shapes. We find that a realistic nucleon--nucleon potential leads to a significant increase in the neutronic specific heat with respect to that obtained assuming a uniform neutron distribution. The increase is largest for the non--spherical phase of the crust. These results may have consequences for the thermal history of young neutron stars.Comment: Revtex, 5 pages, 4 figures included as uuencoded p

Sequential processing in young and older adults in the equiprobable auditory Go/NoGo task

Objective: We recently proposed a sequential processing schema for the equiprobable auditory Go/NoGo task, based on a principal components analysis (PCA) of event-related potentials (ERPs) from a university student sample. Here we sought to replicate the schema, and use it to explore processing in well-functioning older adults. Methods: We compared behavioural responding and ERPs of 20 independent-living older adults (Mage = 68.2 years) to data from a sex- and handedness-matched group of university students (Mage = 20.4 years). ERPs had substantial latency differences between the groups, and hence were subjected to separate group temporal PCAs. Results: Component latencies were systematically increased in the older group by some 26%, with no significant increase in RT or error rates. Despite some differences in their identified components, each group displayed differential component responsivity to Go versus NoGo; this was reduced in the older participants. Conclusion: The results support our processing schema, and provide insight into the processing stages in well-functioning older adults. Significance: Understanding the perceptual and cognitive processing stages in normal ageing is a pre-requisite for research on mild cognitive impairment and dementia. This study may also provide a simple paradigm and schema suitable for further exploration of functionality in ageing

Preliminary study on the assessment of visceral adipose tissue using dual-energy x-ray absorptiometry in chronic obstructive pulmonary disease

Background: Visceral adipose tissue (VAT) was shown to be increased in patients with chronic obstructive pulmonary disease (COPD) compared to control subjects with comparable body mass index (BMI). Our aim was to determine the relation of VAT by dual-energy x-ray absorptiometry (DEXA) in patients with COPD by disease severity, BMI, other indices of body composition and static lung volumes. Methods: 294 COPD patients admitted for rehabilitation were studied. Lung function, static lung volumes and body composition (i.e. BMI, waist circumference, fat-free mass, fat mass and fat distribution between android and gynoid fat mass) were assessed before entering pulmonary rehabilitation. VAT was estimated within the android region by using DEXA. Patients were stratified for gender, BMI (cut-off of 25 kg/m2) and GOLD stage. To assess the impact of VAT on lung volumes, patients were also stratified for VAT less and above 50th percentile. Results: Both male and female patients with more severe airflow limitation had significantly lower VAT values, but these differences disappeared after stratification for BMI. VAT was significantly and strongly correlated with other body composition parameters (all p < 0.001). Patients with moderate to severe airflow limitation and lower VAT had increased static lung hyperinflation and lower diffusing capacity for carbon monoxide. Nevertheless, multivariate stepwise regression models including for BMI, age, gender and forced expiratory volume in 1 s (FEV1) as confounders did not confirm an independent role for VAT on static lung hyperinflation and diffusion capacity. Conclusion: After stratification for BMI, VAT is comparable in moderate to very severe COPD patients. Furthermore, BMI and demographics, but not VAT, were independent predictors of static lung hyperinflation and diffusing capacity in COPD

Direct and indirect effects of rotavirus vaccination: Comparing predictions from transmission dynamic models

Early observations from countries that have introduced rotavirus vaccination suggest that there may be indirect protection for unvaccinated individuals, but it is unclear whether these benefits will extend to the long term. Transmission dynamic models have attempted to quantify the indirect protection that might be expected from rotavirus vaccination in developed countries, but results have varied. To better understand the magnitude and sources of variability in model projections, we undertook a comparative analysis of transmission dynamic models for rotavirus. We fit five models to reported rotavirus gastroenteritis (RVGE) data from England and Wales, and evaluated outcomes for short- and long-term vaccination effects. All of our models reproduced the important features of rotavirus epidemics in England and Wales. Models predicted that during the initial year after vaccine introduction, incidence of severe RVGE would be reduced 1.8-2.9 times more than expected from the direct effects of the vaccine alone (28-50% at 90% coverage), but over a 5-year period following vaccine introduction severe RVGE would be reduced only by 1.1-1.7 times more than expected from the direct effects (54-90% at 90% coverage). Projections for the long-term reduction of severe RVGE ranged from a 55% reduction at full coverage to elimination with at least 80% coverage. Our models predicted short-term reductions in the incidence of RVGE that exceeded estimates of the direct effects, consistent with observations from the United States and other countries. Some of the models predicted that the short-term indirect benefits may be offset by a partial shifting of the burden of RVGE to older unvaccinated individuals. Nonetheless, even when such a shift occurs, the overall reduction in severe RVGE is considerable. Discrepancies among model predictions reflect uncertainties about age variation in the risk and reporting of RVGE, and the duration of natural and vaccine-induced immunity, highlighting important questions for future research

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A Transgenic Rat for Investigating the Anatomy and Function of Corticotrophin Releasing Factor Circuits.

Corticotrophin-releasing factor (CRF) is a 41 amino acid neuropeptide that coordinates adaptive responses to stress. CRF projections from neurons in the central nucleus of the amygdala (CeA) to the brainstem are of particular interest for their role in motivated behavior. To directly examine the anatomy and function of CRF neurons, we generated a BAC transgenic Crh-Cre rat in which bacterial Cre recombinase is expressed from the Crh promoter. Using Cre-dependent reporters, we found that Cre expressing neurons in these rats are immunoreactive for CRF and are clustered in the lateral CeA (CeL) and the oval nucleus of the BNST. We detected major projections from CeA CRF neurons to parabrachial nuclei and the locus coeruleus, dorsal and ventral BNST, and more minor projections to lateral portions of the substantia nigra, ventral tegmental area, and lateral hypothalamus. Optogenetic stimulation of CeA CRF neurons evoked GABA-ergic responses in 11% of non-CRF neurons in the medial CeA (CeM) and 44% of non-CRF neurons in the CeL. Chemogenetic stimulation of CeA CRF neurons induced Fos in a similar proportion of non-CRF CeM neurons but a smaller proportion of non-CRF CeL neurons. The CRF1 receptor antagonist R121919 reduced this Fos induction by two-thirds in these regions. These results indicate that CeL CRF neurons provide both local inhibitory GABA and excitatory CRF signals to other CeA neurons, and demonstrate the value of the Crh-Cre rat as a tool for studying circuit function and physiology of CRF neurons

Effects of a walking aid in COPD patients receiving oxygen therapy

STUDY OBJECTIVES: To elucidate whether a simple walking aid may improve physical performance in COPD patients with chronic respiratory insufficiency who usually carry their own heavy oxygen canister. DESIGN: Randomized crossover trial. SETTING: Physiopathology laboratory of three rehabilitation centers. PATIENTS AND INTERVENTIONS: We studied 60 stable COPD patients (mean age, 70.6 +/- 7.9 years; FEV(1), 44.8 +/- 14.3% of predicted [+/- SD]) with chronic respiratory insufficiency who randomly performed, on 2 consecutive days, a standardized 6-min walking test using two different modalities: a full-weight oxygen canister transported using a small wheeled cart and pulled by the patient (Aid modality) or full-weight oxygen canister carried on the patient's shoulder (No-Aid modality). MEASUREMENTS AND RESULTS: The distance walked, peak effort dyspnea, and leg fatigue scores as primary outcomes, and other cardiorespiratory parameters as secondary outcomes were recorded during both tests. A significant difference (p &lt; 0.05) between the two tests occurred for all the measured outcomes in favor of the Aid modality. Most importantly, significant changes for distance (+ 43 m, p &lt; 0.001), peak effort dyspnea (- 2.0 points, p &lt; 0.001), leg fatigue (- 1.4 points, p &lt; 0.001), as well as for mean and nadir oxygen saturation and heart rate with the Aid modality (but not with the No-Aid modality) were recorded in the subgroup of patients walking &lt; 300 m at baseline. CONCLUSIONS: This study suggests that a simple walking aid may be helpful in COPD patients receiving long-term oxygen therapy, particularly in those with lower residual exercise capacity

Semiclassical Approximation to Neutron Star Superfluidity Corrected for Proximity Effects

The inner crust of a neutron star is a superfluid and inhomogeneous system, consisting of a lattice of nuclei immersed in a sea of neutrons. We perform a quantum calculation of the associated pairing gap and compare it to the results one obtains in the Local Density Approximation (LDA). It is found that the LDA overestimates the spatial dependence of the gap, and leads to a specific heat of the system which is too large at low temperatures, as compared with the quantal result. This is caused by the neglect of proximity effects and the delocalized character of the single-particle wavefunctions close to the Fermi energy. It is possible to introduce an alternative, simple semiclassical approximation of the pairing gap which leads to a specific heat that is in good agreement with the quantum calculation.Comment: RevteX, 8 Postscript Figure