5,028 research outputs found
UV Upturn in Elliptical Galaxies: Theory
The UV upturn is the rising flux with decreasing wavelength between the Lyman
limit and 2500\AA found virtually in all bright spheroidal galaxies. It has
been a mystery ever since it was first detected by the OAO-2 space telescope
(Code & Welch 1979) because such old metal-rich populations were not expected
to contain any substantial number of hot stars. It was confirmed by following
space missions, ANS (de Boer 1982), IUE (Bertola et al. 1982) and HUT (Brown et
al. 1997). The positive correlation between the UV-to-optical colour (i.e., the
strength of the UV upturn) and the Mg2 line strength found by Burstein et al.
(1987) through IUE observations has urged theorists to construct novel
scenarios in which metal-rich () old ( a few Gyr)
stars become UV bright (Greggio & Renzini 1990; Horch et al. 1992). Also
interesting was to find using HUT that, regardless of the UV strength, the UV
spectral slopes at 1000--2000\AA in the six UV bright galaxies were nearly
identical suggesting a very small range of temperatures of the UV sources in
these galaxies (Brown et al. 1997), which corresponds to K. This, together with other evidence, effectively ruled out
young stars as the main driver of the UV upturn. A good review on the
observational side of the story is given in the next article by Tom Brown, as
well as in the recent articles of Greggio & Renzini (1999) and O'Connell
(1999).Comment: 6 figures; belated paper from Keele Conferenc
Some recent progress on quark pairings in dense quark and nuclear matter
We give a brief overview on some recent progress in quark pairings in dense
quark/nuclear matter mostly developed in the past five years. We focus on
following aspects in particular: the BCS-BEC crossover in the CSC phase, the
baryon formation and dissociation in dense quark/nuclear matter, the
Ginzburg-Landau theory for three-flavor dense matter with (1) anomaly,
and the collective and Nambu-Goldstone modes for the spin-one CSC.Comment: RevTex 4, 25 pages, 9 figures, presented for the KITPC (Kavli
Institute for Theoretical Physics China) program "AdS/CFT and Novel
Approaches to Hadron and Heavy Ion Physics' in Oct. 11- Dec. 3, 201
Decoding study-independent mind-wandering from EEG using convolutional neural networks
Objective. Mind-wandering is a mental phenomenon where the internal thought process disengages from the external environment periodically. In the current study, we trained EEG classifiers using convolutional neural networks (CNNs) to track mind-wandering across studies. Approach. We transformed the input from raw EEG to band-frequency information (power), single-trial ERP (stERP) patterns, and connectivity matrices between channels (based on inter-site phase clustering). We trained CNN models for each input type from each EEG channel as the input model for the meta-learner. To verify the generalizability, we used leave-N-participant-out cross-validations (N = 6) and tested the meta-learner on the data from an independent study for across-study predictions. Main results. The current results show limited generalizability across participants and tasks. Nevertheless, our meta-learner trained with the stERPs performed the best among the state-of-the-art neural networks. The mapping of each input model to the output of the meta-learner indicates the importance of each EEG channel. Significance. Our study makes the first attempt to train study-independent mind-wandering classifiers. The results indicate that this remains challenging. The stacking neural network design we used allows an easy inspection of channel importance and feature maps.</p
Distinguishing Vigilance Decrement and Low Task Demands from Mind-wandering:A Machine Learning Analysis of EEG
Mind-wandering is a ubiquitous mental phenomenon that is defined as self-generated thought irrelevant to the ongoing task. Mind-wandering tends to occur when people are in a low-vigilance state or when they are performing a very easy task. In the current study, we investigated whether mind-wandering is completely dependent on vigilance and current task demands, or whether it is an independent phenomenon. To this end, we trained support vector machine (SVM) classifiers on EEG data in conditions of low and high vigilance, as well as under conditions of low and high task demands, and subsequently tested those classifiers on participants' self-reported mind-wandering. Participants' momentary mental state was measured by means of intermittent thought probes in which they reported on their current mental state. The results showed that neither the vigilance classifier nor the task demands classifier could predict mind-wandering above-chance level, while a classifier trained on self-reports of mind-wandering was able to do so. This suggests that mind-wandering is a mental state different from low vigilance or performing tasks with low demands—both which could be discriminated from the EEG above chance. Furthermore, we used dipole fitting to source-localize the neural correlates of the most import features in each of the three classifiers, indeed finding a few distinct neural structures between the three phenomena. Our study demonstrates the value of machine-learning classifiers in unveiling patterns in neural data and uncovering the associated neural structures by combining it with an EEG source analysis technique
Transportation and language access as crucial pillars for an immigrant-inclusive 21st-century food security program
Though food insecurity has long been recognised to impact health, population-specific determinants of food insecurity have recently been studied systematically as an important public health concern. Indeed, while immigrant populations face particular challenges to equitable access to the food system, many of these concerns have not been systematically described. To this end, we critically review recent work that demonstrates the importance of transportation and language access as independent determinants of access to food for immigrant populations. Furthermore, we highlight proposals to mitigate barriers to access, including both academic and community-driven approaches to create overlapping institutional commitments for inclusive policymaking that meets the specific needs of diverse populations
Probing dipolar effects with condensate shape oscillation
We discuss the low energy shape oscillations of a magnetic trapped atomic
condensate including the spin dipole interaction. When the nominal isotropic
s-wave interaction strength becomes tunable through a Feshbach resonance (e.g.
as for Rb atoms), anisotropic dipolar effects are shown to be detectable
under current experimental conditions [E. A. Donley {\it et al.}, Nature {\bf
412}, 295 (2001)].Comment: revised version, submitte
Mural granulosa cell gene expression associated with oocyte developmental competence
<p>Abstract</p> <p>Background</p> <p>Ovarian follicle development is a complex process. Paracrine interactions between somatic and germ cells are critical for normal follicular development and oocyte maturation. Studies have suggested that the health and function of the granulosa and cumulus cells may be reflective of the health status of the enclosed oocyte. The objective of the present study is to assess, using an <it>in vivo </it>immature rat model, gene expression profile in granulosa cells, which may be linked to the developmental competence of the oocyte. We hypothesized that expression of specific genes in granulosa cells may be correlated with the developmental competence of the oocyte.</p> <p>Methods</p> <p>Immature rats were injected with eCG and 24 h thereafter with anti-eCG antibody to induce follicular atresia or with pre-immune serum to stimulate follicle development. A high percentage (30-50%, normal developmental competence, NDC) of oocytes from eCG/pre-immune serum group developed to term after embryo transfer compared to those from eCG/anti-eCG (0%, poor developmental competence, PDC). Gene expression profiles of mural granulosa cells from the above oocyte-collected follicles were assessed by Affymetrix rat whole genome array.</p> <p>Results</p> <p>The result showed that twelve genes were up-regulated, while one gene was down-regulated more than 1.5 folds in the NDC group compared with those in the PDC group. Gene ontology classification showed that the up-regulated genes included lysyl oxidase (<it>Lox</it>) and nerve growth factor receptor associated protein 1 (<it>Ngfrap1</it>), which are important in the regulation of protein-lysine 6-oxidase activity, and in apoptosis induction, respectively. The down-regulated genes included glycoprotein-4-beta galactosyltransferase 2 (<it>Ggbt2</it>), which is involved in the regulation of extracellular matrix organization and biogenesis.</p> <p>Conclusions</p> <p>The data in the present study demonstrate a close association between specific gene expression in mural granulosa cells and the developmental competence of oocytes. This finding suggests that the most differentially expressed gene, lysyl oxidase, may be a candidate biomarker of oocyte health and useful for the selection of good quality oocytes for assisted reproduction.</p
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