13,524 research outputs found
Simultaneous analysis of elastic scattering and transfer/breakup channels for the 6He+208Pb reaction at energies near the Coulomb barrier
The elastic and alpha-production channels for the 6He+208Pb reaction are
investigated at energies around the Coulomb barrier (E_{lab}=14, 16, 18, 22,
and 27 MeV). The effect of the two-neutron transfer channels on the elastic
scattering has been studied within the Coupled-Reaction-Channels (CRC) method.
We find that the explicit inclusion of these channels allows a simultaneous
description of the elastic data and the inclusive alpha cross sections at
backward angles. Three-body Continuum-Discretized Coupled-Channels (CDCC)
calculations are found to reproduce the elastic data, but not the
transfer/breakup data. The trivially-equivalent local polarization potential
(TELP) derived from the CRC and CDCC calculations are found to explain the
features found in previous phenomenological optical model calculations for this
system.Comment: 7 pages, 6 figures (replaced with updated version
Acute fasting before conception affects metabolic and endocrine status without impacting follicle and oocyte development and embryo gene expression in the rabbit.
Food deprivation affects female reproduction. The goal of the present study was to elucidate in the rabbit model the effects of acute energy restriction on ovarian function (follicle development, atresia rate and in vitro oocyte maturation) and embryonic development and gene expression of some candidate genes. Serum metabolic parameters (non-esterified fatty acids (NEFA), triglycerides, glucose, insulin and leptin concentrations) and endocrine markers (oestradiol-17β and progesterone concentrations) were also studied. A control group of nulliparous does fed ad libitum and a 72-h fasted group were used. At the end of the nutritional treatment, the ovaries of half of the animals were retrieved while the other animals were re-fed and artificially inseminated to recover embryos at 84 h after insemination, during the luteal phase. At the end of fasting, increased serum NEFA and decreased leptin concentrations were observed in the fasted group, but no differences appeared in serum steroid concentrations, follicle population and atresia rate or nuclear and cytoplasmic oocyte maturation. In the luteal phase, insulin concentrations increased notably in the fasted group. The number of recovered embryos per female and the speed of embryo development were reduced in the food-deprived group. Acute fasting altered both metabolic and endocrine markers and embryo development, but follicle and oocyte development and embryo gene expression were not affected
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Inverse association between negative symptoms and body mass index in chronic schizophrenia.
BACKGROUND: We investigated whether negative symptoms, such as poor motivation or anhedonia, were associated with higher body mass index (BMI) in stable patients with schizophrenia chronically treated with antipsychotic medication. METHODS: 62 olanzapine- or clozapine-treated patients with illness duration of at least four years were selected from an international multicenter study on the characterization of negative symptoms. All participants completed the Brief Negative Symptom Scale (BNSS) and the Positive and Negative Syndrome Scale (PANSS). Bivariate correlations between BMI and negative symptoms (BNSS) were explored, as well as multiple regression analyses. We further explored the association of two principal component factors of the BNSS and BMI. Subsidiary analyses re-modeled the above using the negative symptoms subscale of the PANSS and the EMSLEY factor for negative symptoms for convergent validity. RESULTS: Lower negative symptoms (BNSS score) were associated with higher BMI (r=-0.31; p=0.015). A multiple regression analysis showed that negative symptoms (BNSS score) and age were significant predictors of BMI (p=0.037). This was mostly driven by the motivation/pleasure factor of the BNSS. Within this second factor, BMI was negatively associated with anhedonia (r=-0.254; p=0.046) and asociality (r=-0.253; p=0.048), but not avolition (r=-0.169; p=0.188). EMSLEY score was positively associated with BNSS (r=0.873, p<0.001), but negatively associated with BMI (r=-0.308; p=0.015). The association between PANSS and BMI did not reach significance (r=-224, p=0.080). CONCLUSIONS: We conclude that lower negative symptoms were associated with higher BMI (assessed using both the BNSS and EMSLEY) in chronic stable schizophrenia patients, mostly due to lower anhedonia and asociality levels
Overview of methods used to evaluate the adequacy of nutrient intakes for individuals and populations
The objective of the present paper is to review the methods of measuring micronutrient intake adequacy for individuals and for populations in order to ascertain best practice. A systematic review was conducted to locate studies on the methodological aspects of measuring nutrient adequacy. The results showed that for individuals, qualitative methods (to find probability of adequacy) and quantitative methods (to find confidence of adequacy) have been proposed for micronutrients where there is enough data to set an average nutrient requirement (ANR). If micronutrients do not have ANR, an adequate intake (AI) is often defined and can be used to assess adequacy, provided the distribution of daily intake over a number of days is known. The probability of an individual's intake being excessive can also be compared with the upper level of safe intake and the confidence of this estimate determined in a similar way. At the population level, adequacy can be judged from the ANR using the probability approach or its short cut – the estimated average requirement cut-point method. If the micronutrient does not have an ANR, adequacy cannot be determined from the average intake and must be expressed differently. The upper level of safe intake can be used for populations in a similar way to that of individuals. All of the methodological studies reviewed were from the American continent and all used the methodology described in the Institute of Medicine publications. The present methodology should now be adapted for use in Europe
Ultra-short Period Binaries from the Catalina Surveys
We investigate the properties of 367 ultra-short period binary candidates
selected from 31,000 sources recently identified from Catalina Surveys data.
Based on light curve morphology, along with WISE, SDSS and GALEX multi-colour
photometry, we identify two distinct groups of binaries with periods below the
0.22 day contact binary minimum. In contrast to most recent work, we
spectroscopically confirm the existence of M-dwarf+M-dwarf contact binary
systems. By measuring the radial velocity variations for five of the
shortest-period systems, we find examples of rare cool-white dwarf+M-dwarf
binaries. Only a few such systems are currently known. Unlike warmer white
dwarf systems, their UV flux and their optical colours and spectra are
dominated by the M-dwarf companion. We contrast our discoveries with previous
photometrically-selected ultra-short period contact binary candidates, and
highlight the ongoing need for confirmation using spectra and associated radial
velocity measurements. Overall, our analysis increases the number of
ultra-short period contact binary candidates by more than an order of
magnitude.Comment: 12 pages, 12 figures, accepted Ap
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