56 research outputs found

    Detailed Spectroscopic and Photometric Analysis of DQ White Dwarfs

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    We present an analysis of spectroscopic and photometric data for cool DQ white dwarfs based on improved model atmosphere calculations. In particular, we revise the atmospheric parameters of the trigonometric parallax sample of Bergeron et al.(2001), and discuss the astrophysical implications on the temperature scale and mean mass, as well as the chemical evolution of these stars. We also analyze 40 new DQ stars discovered in the first data release of the Sloan Digital Sky Survey.Comment: 6 pages,3 figures, 14th European Workshop on White Dwarfs, ASP Conference Series, in pres

    Assessment of neuroactive steroids in cerebrospinal fluid comparing acute relapse and stable disease in relapsing-remitting multiple sclerosis

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    Previous studies have reported an involvement of neuroactive steroids as neuroprotective and anti-inflammatory agents in neurological disorders such as multiple sclerosis (MS); an analysis of their profile during a specific clinical phase of MS is largely unknown. The pregnenolone (PREG), dehydroepiandrosterone (DHEA), and allopregnanolone (ALLO) profile was evaluated in cerebrospinal fluid (CSF) in relapsing-remitting multiple sclerosis (RR-MS) patients as well as those in patients affected by non-inflammatory neurological (control group I) and without neurological disorders (control group II). An increase of PREG and DHEA values was shown in CSF of male and female RR-MS patients compared to those observed in both control groups. The ALLO values were significantly lower in female RR-MS patients than those found in male RR-MS patients and in female without neurological disorder. During the clinical relapse, we observed female RR-MS patients showing significantly increased PREG values compared to female RR-MS patients in stable phase, while their ALLO values showed a significant decrease compared to male RR-MS patients of the same group. Male RR-MS patients with gadolinium-enhanced lesions showed PREG and DHEA values higher than those found in female RR-MS patients with gadolinium-enhanced lesions. Similary, male RR-MS patients with gadolinium-enhanced lesions showed PREG and DHEA values higher than male without gadolinium-enhanced lesions. Female RR-MS patients with gadolinium-enhanced lesions showed DHEA values higher than those found in female RR-MS patients with gadolinium-enhanced lesions. Male and female RR-MS patients with gadolinium-enhanced lesions showed ALLO values higher than those found in respective gender groups without gadolinium-enhanced lesions. ALLO values were lower in male than in female RR-MS patients without gadolinium-enhanced lesions. Considering the pharmacological properties of neuroactive steroids and the observation that neurological disorders influence their concentrations, these endogenous compounds may have an important role as prognostic factors of the disease and used as markers of MS activity such as relapses

    Digital technologies, legal design and the future of the legal profession

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    Legal Technology – or “Legal Tech” – is disrupting the traditional operations and self-understanding of the legal profession. This chapter introduces the central claim of this book, namely that these developments are having and will continue to have a disruptive effect on the work of lawyers and that adapting to this new operating environment is crucial for legal professionals remaining relevant in an increasingly technology-driven world. This introductory chapter outlines some of the main features of this on-going transformation process, introduces some of the pressures it is creating for lawyers, and provides short summaries of the chapters that comprise this collection.fi=vertaisarvioitu|en=peerReviewed

    Consensus Statement on Proton Therapy in Mesothelioma

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    Purpose: Radiation therapy for mesothelioma remains challenging, as normal tissue toxicity limits the amount of radiation that can be safely delivered to the pleural surfaces, especially radiation dose to the contralateral lung. The physical properties of proton therapy result in better sparing of normal tissues when treating the pleura, both in the postpneumonectomy setting and the lung-intact setting. Compared with photon radiation, there are dramatic reductions in dose to the contralateral lung, heart, liver, kidneys, and stomach. However, the tissue heterogeneity in the thorax, organ motion, and potential for changing anatomy during the treatment course all present challenges to optimal irradiation with protons. Methods: The clinical data underlying proton therapy in mesothelioma are reviewed here, including indications, advantages, and limitations. Results: The Particle Therapy Cooperative Group Thoracic Subcommittee task group provides specific guidelines for the use of proton therapy for mesothelioma. Conclusions: This consensus report can be used to guide clinical practice, insurance approval, and future research

    The origin and abundances of the chemical elements

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    The influence of diffusion and mass loss on the chemical composition of subdwarf B stars

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    We investigate the influence of diffusion and mass loss on the chemical composition in subdwarf B stars in the range 25000KTeff35000K25 000 {\rm K} \leq T_{\rm eff} \leq 35 000 {\rm K}, 5.5logg6.05.5 \leq \log g \leq 6.0. Within the outer hydrogen-rich envelope characterized by mass < 102M10^{-2} M_{*} for the elements H, He, C, N and O the equations of continuity, the momentum equations and the equation of radiative transfer are solved simultaneously. For various mass loss rates the time evolution of the chemical composition is predicted within time scales of ≈ 108yr10^{8} {\rm yr}, which correspond to the typical lifetimes of the sdB's near the Extended Horizontal Branch. According to the results weak winds with M˙1013M/yr\dot M \approx 10^{-13} M_{\odot} / \rm yr may explain the typical helium deficiencies by more than one order of magnitude in the atmospheres of these stars. Winds with 1014M/yr<M˙<1013M/yr10^{-14} M_{\odot} / {\rm yr} < \dot M < 10^{-13} M_{\odot} / \rm yr may lead to strong deficiencies as well as to enrichments of the CNO elements. The composition in the outer envelope changes in time scales similar to the typical lifetimes of the sdB's. From estimates of the radiative acceleration in the wind region, which make the existence of weak winds plausible, and from a comparison with the case of hot white dwarfs we suggest that the abundance anomalies observed in sdB stars are related to the combined effects of diffusion and mass loss
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