The Effect of Crystallization on the Pulsations of White Dwarf Stars

We consider the pulsational properties of white dwarf star models with temperatures appropriate for the ZZ Ceti instability strip and with masses large enough that they should be substantially crystallized. Our work is motivated by the existence of a potentially crystallized DAV, BPM 37093, and the expectation that digital surveys in progress will yield many more such massive pulsators. A crystallized core makes possible a new class of oscillations, the torsional modes, although we expect these modes to couple at most weakly to any motions in the fluid and therefore to remain unobservable. The p-modes should be affected at the level of a few percent in period, but are unlikely to be present with observable amplitudes in crystallizing white dwarfs any more than they are in the other ZZ Ceti's. Most relevant to the observed light variations in white dwarfs are the g-modes. We find that the kinetic energy of these modes is effectively excluded from the crystallized cores of our models. As increasing crystallization pushes these modes farther out from the center, the mean period spacing between radial overtones increases substantially with the crystallized mass fraction. In addition, the degree and structure of mode trapping is affected. The fact that some periods are strongly affected by changes in the crystallized mass fraction while others are not suggests that we may be able to disentangle the effects of crystallization from those due to different surface layer masses.Comment: 18 pages, 5 figures, accepted on 1999 July 2 for publication in the Astrophysical Journa

Large-scale ATLAS simulated production on EGEE

In preparation for first data at the LHC, a series of Data Challenges, of increasing scale and complexity, have been performed. Large quantities of simulated data have been produced on three different Grids, integrated into the ATLAS production system. During 2006, the emphasis moved towards providing stable continuous production, as is required in the immediate run-up to first data, and thereafter. Here, we discuss the experience of the production done on EGEE resources, using submission based on the gLite WMS, CondorG and a system using Condor Glide-ins. The overall walltime efficiency of around 90% is largely independent of the submission method, and the dominant source of wasted cpu comes from data handling issues. The efficiency of grid job submission is significantly worse than this, and the glide-in method benefits greatly from factorising this out

Catalog of Galactic Beta Cephei Stars

We present an extensive and up-to-date catalog of Galactic Beta Cephei stars. This catalog is intended to give a comprehensive overview of observational characteristics of all known Beta Cephei stars. 93 stars could be confirmed to be Beta Cephei stars. For some stars we re-analyzed published data or conducted our own analyses. 61 stars were rejected from the final Beta Cephei list, and 77 stars are suspected to be Beta Cephei stars. A list of critically selected pulsation frequencies for confirmed Beta Cephei stars is also presented. We analyze the Beta Cephei stars as a group, such as the distributions of their spectral types, projected rotational velocities, radial velocities, pulsation periods, and Galactic coordinates. We confirm that the majority of these stars are multiperiodic pulsators. We show that, besides two exceptions, the Beta Cephei stars with high pulsation amplitudes are slow rotators. We construct a theoretical HR diagram that suggests that almost all 93 Beta Cephei stars are MS objects. We discuss the observational boundaries of Beta Cephei pulsation and their physical parameters. We corroborate that the excited pulsation modes are near to the radial fundamental mode in frequency and we show that the mass distribution of the stars peaks at 12 solar masses. We point out that the theoretical instability strip of the Beta Cephei stars is filled neither at the cool nor at the hot end and attempt to explain this observation

Obesity treatment—more than food and exercise: a qualitative study exploring obese adolescents' and their parents' views on the former's obesity

The aim of this study was to explore obese adolescents’ and their parents’ views on the former's obesity; especially to gain knowledge about barriers and motivational factors that influence obese adolescents’ ability to lose weight. This is a qualitative study involving field observation and semi-structured interviews with obese adolescents and their parents. The analysis takes a phenomenological–hermeneutic approach. Fifteen obese adolescents aged 13–16 years and their parents/grandparents participated in this study (one father, seven mothers, five sets of parents and two sets of grandparents). The results showed that obese adolescents’ are aware that they have unhealthy eating habits and they wish they were able to attain to a healthier diet. Although in poor physical shape, obese adolescents perceive their daily level of exercise as moderate. Obese adolescents blame themselves for being obese and blame their parents for an unhealthy diet, and for being unsupportive regarding exercise. Parents blame their obese child of lacking will power to change eating and exercise habits. As a consequence, the homely atmosphere is often characterised by quarrels and negative feelings. The conclusion is that despite obese adolescents’ intention of reducing weight, underlying issues interfere with this goal. This is particularly related to quarrels with parents, self-blame and misguided understanding of eating and exercising habits. These matters need to be addressed when treating obesity among adolescents

Single-Unit Activity in the Medial Prefrontal Cortex during Immediate and Delayed Extinction of Fear in Rats

Delivering extinction trials minutes after fear conditioning yields only a short-term fear suppression that fully recovers the following day. Because extinction has been reported to increase CS-evoked spike firing and spontaneous bursting in the infralimbic (IL) division of the medial prefrontal cortex (mPFC), we explored the possibility that this immediate extinction deficit is related to altered mPFC function. Single-units were simultaneously recorded in rats from neurons in IL and the prelimbic (PrL) division of the mPFC during an extinction session conducted 10 minutes (immediate) or 24 hours (delayed) after auditory fear conditioning. In contrast to previous reports, IL neurons exhibited CS-evoked responses early in extinction training in both immediate and delayed conditions and these responses decreased in magnitude over the course of extinction training. During the retention test, CS-evoked firing in IL was significantly greater in animals that failed to acquire extinction. Spontaneous bursting during the extinction and test sessions was also different in the immediate and delayed groups. There were no group differences in PrL activity during extinction or retention testing. Alterations in both spontaneous and CS-evoked neuronal activity in the IL may contribute to the immediate extinction deficit

Restoring the orangutan in a Whole- or Half-Earth context

Various global-scale proposals exist to reduce the loss of biological diversity. These include the Half-Earth and Whole-Earth visions that respectively seek to set aside half the planet for wildlife conservation or to diversify conservation practices fundamentally and change the economic systems that determine environmental harm. Here we assess these visions in the specific context of Bornean orangutans Pongo pygmaeus and their conservation. Using an expert-led process we explored three scenarios over a 10-year time frame: continuation of Current Conditions, a Half-Earth approach and a Whole-Earth approach. In addition, we examined a 100-year population recovery scenario assuming 0% offtake of Bornean orangutans. Current Conditions were predicted to result in a population c. 73% of its current size by 2032. Half-Earth was judged comparatively easy to achieve and predicted to result in an orangutan population of c. 87% of its current size by 2032. Whole-Earth was anticipated to lead to greater forest loss and ape killing, resulting in a prediction of c. 44% of the current orangutan population for 2032. Finally, under the recovery scenario, populations could be c. 148% of their current size by 2122. Although we acknowledge uncertainties in all of these predictions, we conclude that the Half-Earth and Whole-Earth visions operate along different timelines, with the implementation of Whole-Earth requiring too much time to benefit orangutans. None of the theorized proposals provided a complete solution, so drawing elements from each will be required. We provide recommendations for equitable outcomes

Subacute and chronic, non-specific back and neck pain: cognitive-behavioural rehabilitation versus primary care. A randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>In the industrial world, non-specific back and neck pain (BNP) is the largest diagnostic group underlying sick-listing. For patients with subacute and chronic (= full-time sick-listed for 43 – 84 and 85 – 730 days, respectively) BNP, cognitive-behavioural rehabilitation was compared with primary care. The specific aim was to answer the question: within an 18-month follow-up, will the outcomes differ in respect of sick-listing and number of health-care visits?</p> <p>Methods</p> <p>After stratification by age (≤ 44/≥ 45 years) and subacute/chronic BNP, 125 Swedish primary-care patients were randomly allocated to cognitive-behavioural rehabilitation (rehabilitation group) or continued primary care (primary-care group). Outcome measures were <it>Return-to-work share </it>(percentage) and <it>Return-to-work chance </it>(hazard ratios) over 18 months, <it>Net days </it>(crude sick-listing days × degree), and the number of <it>Visits </it>(to physicians, physiotherapists etc.) over 18 months and the three component six-month periods. Descriptive statistics, Cox regression and mixed-linear models were used.</p> <p>Results</p> <p>All patients: <it>Return-to-work share </it>and <it>Return-to-work chance </it>were equivalent between the groups. <it>Net days </it>and <it>Visits </it>were equivalent over 18 months but decreased significantly more rapidly for the rehabilitation group over the six-month periods (<it>p </it>< .05). Subacute patients: <it>Return-to-work share </it>was equivalent. <it>Return-to-work chance </it>was significantly greater for the rehabilitation group (hazard ratio 3.5 [95%CI1.001 – 12.2]). <it>Net days </it>were equivalent over 18 months but decreased significantly more rapidly for the rehabilitation group over the six-month periods and there were 31 days fewer in the third period. <it>Visits </it>showed similar though non-significant differences and there were half as many in the third period. Chronic patients: <it>Return-to-work share, Return-to-work chance </it>and <it>Net days </it>were equivalent. <it>Visits </it>were equivalent over 18 months but tended to decrease more rapidly for the rehabilitation group and there were half as many in the third period (non-significant).</p> <p>Conclusion</p> <p>The results were equivalent over 18 months. However, there were indications that cognitive-behavioural rehabilitation in the longer run might be superior to primary care. For subacute BNP, it might be superior in terms of sick-listing and health-care visits; for chronic BNP, in terms of health-care visits only. More conclusive results concerning this possible long-term effect might require a longer follow-up.</p> <p>Trial registration</p> <p>NCT00488735.</p

Changes in Brain MicroRNAs Contribute to Cholinergic Stress Reactions

Mental stress modifies both cholinergic neurotransmission and alternative splicing in the brain, via incompletely understood mechanisms. Here, we report that stress changes brain microRNA (miR) expression and that some of these stress-regulated miRs regulate alternative splicing. Acute and chronic immobilization stress differentially altered the expression of numerous miRs in two stress-responsive regions of the rat brain, the hippocampal CA1 region and the central nucleus of the amygdala. miR-134 and miR-183 levels both increased in the amygdala following acute stress, compared to unstressed controls. Chronic stress decreased miR-134 levels, whereas miR-183 remained unchanged in both the amygdala and CA1. Importantly, miR-134 and miR-183 share a common predicted mRNA target, encoding the splicing factor SC35. Stress was previously shown to upregulate SC35, which promotes the alternative splicing of acetylcholinesterase (AChE) from the synapse-associated isoform AChE-S to the, normally rare, soluble AChE-R protein. Knockdown of miR-183 expression increased SC35 protein levels in vitro, whereas overexpression of miR-183 reduced SC35 protein levels, suggesting a physiological role for miR-183 regulation under stress. We show stress-induced changes in miR-183 and miR-134 and suggest that, by regulating splicing factors and their targets, these changes modify both alternative splicing and cholinergic neurotransmission in the stressed brain

Overexpression of Dyrk1A Is Implicated in Several Cognitive, Electrophysiological and Neuromorphological Alterations Found in a Mouse Model of Down Syndrome

Down syndrome (DS) phenotypes result from the overexpression of several dosage-sensitive genes. The DYRK1A (dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A) gene, which has been implicated in the behavioral and neuronal alterations that are characteristic of DS, plays a role in neuronal progenitor proliferation, neuronal differentiation and long-term potentiation (LTP) mechanisms that contribute to the cognitive deficits found in DS. The purpose of this study was to evaluate the effect of Dyrk1A overexpression on the behavioral and cognitive alterations in the Ts65Dn (TS) mouse model, which is the most commonly utilized mouse model of DS, as well as on several neuromorphological and electrophysiological properties proposed to underlie these deficits. In this study, we analyzed the phenotypic differences in the progeny obtained from crosses of TS females and heterozygous Dyrk1A (+/-) male mice. Our results revealed that normalization of the Dyrk1A copy number in TS mice improved working and reference memory based on the Morris water maze and contextual conditioning based on the fear conditioning test and rescued hippocampal LTP. Concomitant with these functional improvements, normalization of the Dyrk1A expression level in TS mice restored the proliferation and differentiation of hippocampal cells in the adult dentate gyrus (DG) and the density of GABAergic and glutamatergic synapse markers in the molecular layer of the hippocampus. However, normalization of the Dyrk1A gene dosage did not affect other structural (e.g., the density of mature hippocampal granule cells, the DG volume and the subgranular zone area) or behavioral (i.e., hyperactivity/attention) alterations found in the TS mouse. These results suggest that Dyrk1A overexpression is involved in some of the cognitive, electrophysiological and neuromorphological alterations, but not in the structural alterations found in DS, and suggest that pharmacological strategies targeting this gene may improve the treatment of DS-associated learning disabilities