2,662 research outputs found

    XMM-Newton reveals ~100 new LMXBs in M31 from variability studies

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    We have conducted a survey of X-ray sources in XMM-Newton observations of M31, examining their power density spectra (PDS) and spectral energy distributions (SEDs). Our automated source detection yielded 535 good X-ray sources; to date, we have studied 225 of them. In particular, we examined the PDS because low mass X-ray binaries (LMXBs) exhibit two distinctive types of PDS. At low accretion rates, the PDS is characterised by a broken power law, with the spectral index changing from ~0 to ~1 at some frequency in the range \~0.01--1 Hz; we refer to such PDS as Type A. At higher accretion rates, the PDS is described by a simple power law; we call these PDS Type B. Of the 225 sources studied to date, 75 exhibit Type A variability, and are almost certainly LMXBs, while 6 show Type B but not Type A, and are likely LMXBs. Of these 81 candidate LMXBs, 71 are newly identified in this survey; furthermore, they are mostly found near the centre of M31. Furthermore, most of the X-ray population in the disc are associated with the spiral arms, making them likely high mass X-ray binaries (HMXBs). In general these HMXBs do not exhibit Type A variability, while many central X-ray sources (LMXBs) in the same luminosity range do. Hence the PDS may distinguish between LMXBs and HMXBs in this luminosity range.Comment: 4 pages, 2 figures. To appear in proceedings of IAUS230: "Populations of High Energy Sources in Galaxies", 14-19 August 2005, Dublin, Eds E.J.A. Meurs and G. Fabbian

    SN contributions to GRB lightcurves

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    Several of the nearer GRB afterglows (up to z āˆ¼ 1) show bumps in their lightcurves that have been interpreted as contributions from associated SNae. Thebumps arecustomarily modelled likethet ype-Ic SN 1998bw, but wein vestigate here, for several low-z GRBs, whether other SN types might offer alternatives. While several SN types are ruled out, or are unlikely, a type ā€œII-blā€ could also explain the observations

    Muscarinic receptor signaling in the pathophysiology of asthma and COPD

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    Anticholinergics are widely used for the treatment of COPD, and to a lesser extent for asthma. Primarily used as bronchodilators, they reverse the action of vagally derived acetylcholine on airway smooth muscle contraction. Recent novel studies suggest that the effects of anticholinergics likely extend far beyond inducing bronchodilation, as the novel anticholinergic drug tiotropium bromide can effectively inhibit accelerated decline of lung function in COPD patients. Vagal tone is increased in airway inflammation associated with asthma and COPD; this results from exaggerated acetylcholine release and enhanced expression of downstream signaling components in airway smooth muscle. Vagally derived acetylcholine also regulates mucus production in the airways. A number of recent research papers also indicate that acetylcholine, acting through muscarinic receptors, may in part regulate pathological changes associated with airway remodeling. Muscarinic receptor signalling regulates airway smooth muscle thickening and differentiation, both in vitro and in vivo. Furthermore, acetylcholine and its synthesizing enzyme, choline acetyl transferase (ChAT), are ubiquitously expressed throughout the airways. Most notably epithelial cells and inflammatory cells generate acetylcholine, and express functional muscarinic receptors. Interestingly, recent work indicates the expression and function of muscarinic receptors on neutrophils is increased in COPD. Considering the potential broad role for endogenous acetylcholine in airway biology, this review summarizes established and novel aspects of muscarinic receptor signaling in relation to the pathophysiology and treatment of asthma and COPD

    Conscientiousness, extraversion, and field sales performance: Combining narrow personality, social skill, emotional stability, and nonlinearity

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    This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordAlthough prior research indicated that extraversion and conscientiousness are uniformly beneficial to sales performance, recent evidence suggests that scholars should consider nonlinearity, narrow personality, social skill, and the research context in the personality-performance relation. Further, scholars have found conscientiousness to have inverted U-shaped relationships with performance. Taking these into account, the present study examines the nonlinear relation that the combined conscientiousness facets of discipline and achievement motivation (i.e., disciplined achievement motivation) have with objective sales performance in a predictive study with a nine month time interval. We argue that stable social potency, composed of the activity facet of extraversion, social skill, and emotional stability, will moderate this nonlinear relation in the context of insurance field sales, such that the greatest sales performance will be from those high on both constructs. Our findings support our hypotheses, demonstrating that a relevant social-related trait (i.e., stable social potency) can offset the potential downsides of high disciplined achievement motivation (e.g., perfectionism, and workaholism), helping such individuals to achieve high objective sales. Implications for theory and future research directions are discussed

    Towards sex-specific osteoarthritis risk models: evaluation of risk factors for knee osteoarthritis in males and females

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    Objectives The aim of this study was to identify sex-specific prevalence and strength of risk factors for the incidence of radiographic knee OA (incRKOA). Methods Our study population consisted of 10ā€‰958 Rotterdam Study participants free of knee OA in one or both knees at baseline. One thousand and sixty-four participants developed RKOA after a median follow-up time of 9.6ā€‰years. We estimated the association between each available risk factor and incRKOA using sex stratified multivariate regression models with generalized estimating equations. Subsequently, we statistically tested sex differences between risk estimates and calculated the population attributable fractions (PAFs) for modifiable risk factors. Results The prevalence of the investigated risk factors was, in general, higher in women compared with men, except that alcohol intake and smoking were higher in men and high BMI showed equal prevalence. We found significantly different risk estimates between men and women: high level of physical activity [relative risk (RR) 1.76 (95% CI: 1.29ā€“2.40)] or a Kellgren and Lawrence score 1 at baseline [RR 5.48 (95% CI: 4.51ā€“6.65)] was higher in men. Among borderline significantly different risk estimates was BMI ā‰„27, associated with higher risk for incRKOA in women [RR 2.00 (95% CI: 1.74ā€“2.31)]. The PAF for higher BMI was 25.6% in women and 19.3% in men. Conclusion We found sex-specific differences in both presence and relative risk of several risk factors for incRKOA. Especially BMI, a modifiable risk factor, impacts women more strongly than men. These risk factors can be used in the development of personalized prevention strategies and in building sex-specific prediction tools to identify high risk profile patients

    Prescription of the first prosthesis and later use in children with congenital unilateral upper limb deficiency: A systematic review

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    Background: The prosthetic rejection rates in children with an upper limb transversal reduction deficiency are considerable. It is unclear whether the timing of the first prescription of the prosthesis contributes to the rejection rates. Objective: To reveal whether scientific evidence is available in literature to confirm the hypothesis that the first prosthesis of children with an upper limb deficiency should be prescribed before two years of age. We expect lower rejection rates and better functional outcomes in children fitted at young age. Methods: A computerized search was performed in several databases (Medline, Embase, Cinahl, Amed, Psycinfo, PiCarta and the Cochrane database). A combination of the following keywords and their synonyms was used: "prostheses, upper limb, upper extremity, arm and congenital''. Furthermore, references of conference reports, references of most relevant studies, citations of most relevant studies and related articles were checked for relevancy. Results: The search yielded 285 publications, of which four studies met the selection criteria. The methodological quality of the studies was low. All studies showed a trend of lower rejection rates in children who were provided with their first prosthesis at less than two years of age. The pooled odds ratio of two studies showed a higher rejection rate in children who were fitted over two years of age ( pooled OR 3.6, 95% CI 1.6-8.0). No scientific evidence was found concerning the relation between the age at which a prosthesis was prescribed for the first time and functional outcomes. Conclusion: In literature only little evidence was found for a relationship between the fitting of a first prosthesis in children with a congenital upper limb deficiency and rejection rates or functional outcomes. As such, clinical practice of the introduction of a prosthesis is guided by clinical experience rather than by evidence-based medicine

    ICU at home, with the use of mobile IC unit services:intensive care goes that extra mile

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    In this report we describe a patient with a long ICU stay because of severe Guillain BarrƩ syndrome. Treatment was patient-centred and Mobile ICU facilities were used to facilitate an ICU at home for one day. Early focus on individual needs and wishes and close communication with and within ICU treatment teams can help to improve the long-term consequences of ICU admission. Research on which interventions are effective and most cost-effective need to be performed
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