1,931 research outputs found

    Radio Frequency Models of Novae in eruption. I. The Free-Free Process in Bipolar Morphologies

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    Observations of novae at radio frequencies provide us with a measure of the total ejected mass, density profile and kinetic energy of a nova eruption. The radio emission is typically well characterized by the free-free emission process. Most models to date have assumed spherical symmetry for the eruption, although it has been known for as long as there have been radio observations of these systems, that spherical eruptions are to simplistic a geometry. In this paper, we build bipolar models of the nova eruption, assuming the free-free process, and show the effects of varying different parameters on the radio light curves. The parameters considered include the ratio of the minor- to major-axis, the inclination angle and shell thickness (further parameters are provided in the appendix). We also show the uncertainty introduced when fitting spherical model synthetic light curves to bipolar model synthetic light curves. We find that the optically thick phase rises with the same power law (Sν∝t2S_{\nu} \propto t^2) for both the spherical and bipolar models. In the bipolar case there is a "plateau" phase -- depending on the thickness of the shell as well as the ratio of the minor- to major-axis -- before the final decline, that follows the same power law (Sν∝t−3S_{\nu} \propto t^{-3}) as in the spherical case. Finally, fitting spherical models to the bipolar model synthetic light curves requires, in the worst case scenario, doubling the ejected mass, more than halving the electron temperature and reducing the shell thickness by nearly a factor of 10. This implies that in some systems we have been over predicting the ejected masses and under predicting the electron temperature of the ejecta.Comment: 9 pages, 6 figures, accepted for publication in ApJ, accompanying movie to figure 3 available at http://www.ast.uct.ac.za/~valerio/papers/radioI

    Burden and Needs of Patients with Severe GvHD from the Supportive and Palliative Care Perspective—A Literature Review

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    Graft-versus-host disease (GvHD) is a frequent, and often life-threatening, complication after an allogeneic, hematopoietic stem cell transplantation (allo-SCT). It can appear in an acute or a chronic form and presents different grades of severity. Particularly, the severe forms of GvHD are often responsible for a change of the curative intent for allo-SCT into a palliative goal of care. For this non-systematic review, we conducted a focused literature search in the MEDLINE database via PubMed to examine whether patients with severe forms of GvHD might have special needs and burdens from a supportive and palliative care perspective. To draw a comprehensive picture of this patient group, we included findings on quality of life (QoL) and physical symptoms and function as well as psychological and spiritual well-being. In most domains, patients with severe forms of GvHD showed greater impairment and a higher symptom burden compared to patients with milder forms of GvHD. However, we could not identify any studies that specifically investigated patients with severe forms of GvHD. Further research in this field is necessary to guarantee the highest standard of care for this very special patient group

    Point-of-care detection and differentiation of anticoagulant therapy - development of thromboelastometry-guided decision-making support algorithms

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    BACKGROUND DOAC detection is challenging in emergency situations. Here, we demonstrated recently, that modified thromboelastometric tests can reliably detect and differentiate dabigatran and rivaroxaban. However, whether all DOACs can be detected and differentiated to other coagulopathies is unclear. Therefore, we now tested the hypothesis that a decision tree-based thromboelastometry algorithm enables detection and differentiation of all direct Xa-inhibitors (DXaIs), the direct thrombin inhibitor (DTI) dabigatran, as well as vitamin K antagonists (VKA) and dilutional coagulopathy (DIL) with high accuracy. METHODS Following ethics committee approval (No 17-525-4), and registration by the German clinical trials database we conducted a prospective observational trial including 50 anticoagulated patients (n = 10 of either DOAC/VKA) and 20 healthy volunteers. Blood was drawn independent of last intake of coagulation inhibitor. Healthy volunteers served as controls and their blood was diluted to simulate a 50% dilution in vitro. Standard (extrinsic coagulation assay, fibrinogen assay, etc.) and modified thromboelastometric tests (ecarin assay and extrinsic coagulation assay with low tissue factor) were performed. Statistical analyzes included a decision tree analyzes, with depiction of accuracy, sensitivity and specificity, as well as receiver-operating-characteristics (ROC) curve analysis including optimal cut-off values (Youden-Index). RESULTS First, standard thromboelastometric tests allow a good differentiation between DOACs and VKA, DIL and controls, however they fail to differentiate DXaIs, DTIs and VKAs reliably resulting in an overall accuracy of 78%. Second, adding modified thromboelastometric tests, 9/10 DTI and 28/30 DXaI patients were detected, resulting in an overall accuracy of 94%. Complex decision trees even increased overall accuracy to 98%. ROC curve analyses confirm the decision-tree-based results showing high sensitivity and specificity for detection and differentiation of DTI, DXaIs, VKA, DIL, and controls. CONCLUSIONS Decision tree-based machine-learning algorithms using standard and modified thromboelastometric tests allow reliable detection of DTI and DXaIs, and differentiation to VKA, DIL and controls. TRIAL REGISTRATION Clinical trial number: German clinical trials database ID: DRKS00015704

    A Dynamical Mass Constraint for Pre-Main-Sequence Evolutionary Tracks: The Binary NTT 045251+3016

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    We present an astrometric/spectroscopic orbital solution for the pre-main-sequence binary NTT 045251+3016. Our measurements for the primary and secondary masses are 1.45 +/- 0.19 M_sun and 0.81 +/- 0.09 M_sun, respectively, and 145 +/- 8 pc for the distance of the system, consistent with prior estimates for the Taurus-Auriga star-forming region. The evolutionary tracks of D'Antona & Mazzitelli (1997), Baraffe et al. (1998), and Palla & Stahler (1999) are tested against these dynamical mass measurements. Due to the intrinsic color/T_eff variation within the K5 spectral class, each pre-main-sequence model provides a mass range for the primary. The theoretical mass range derived from the Baraffe et al. (1998) tracks that use a mixing length parameter alpha=1.0 is closest to our measured primary mass, deviating between 1.3 and 1.6 sigma. The set of Baraffe et al. (1998) tracks that use alpha=1.9 deviate between 1.6 and 2.1 sigma from our measured primary mass. The mass range given by the Palla & Stahler (1999) tracks for the primary star deviate between 1.6 and 2.9 sigma. The D'Antona & Mazzitelli (1997) tracks give a mass range that deviates by at least 3.0 sigma from our derived primary mass, strongly suggesting that these tracks are inconsistent with our observation. Observations of the secondary are less constraining than those of the primary, but the deviations between the dynamical mass of the secondary and the mass inferred for the secondary from the various pre-main-sequence tracks mirror the deviations of the primary star. All of the pre-main-sequence tracks are consistent with coevality of the components of NTT 045251+3016.Comment: 27 pages, 6 figures, 5 tables -- accepted by A

    Preliminary Orbit of the Young Binary Haro 1-14c

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    Using the Keck Interferometer, we spatially resolved the orbit of the pre-main sequence binary, Haro 1-14c, for the first time. We present these interferometric observations along with additional spectroscopic radial velocity measurements of the components. We performed a simultaneous orbit fit to the interferometric visibilities and the radial velocities of Haro 1-14c. Based on a statistical analysis of the possible orbital solutions that fit the data, we determined component masses of M_1 = 0.96 (+0.27/-0.08) Msun and M_2 = 0.33 (+0.09/-0.02) Msun for the primary and secondary, respectively, and a distance to the system of 111 (+19/-18) pc. The distance measurement is consistent with the close distance estimates of the Ophiuchus molecular cloud. Comparing our results with evolutionary tracks suggests an age of 3-4 Myr for Haro 1-14c. With additional interferometric measurements to improve the uncertainties in the masses and distance, we expect the low-mass secondary to provide important empirical data for calibrating the theoretical evolutionary tracks for pre-main sequence stars.Comment: 28 pages, 9 figures, accepted for publication in A

    Implementing patient reported outcome measures (PROMs) in palliative care - users' cry for help

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    <p>Abstract</p> <p>Background</p> <p>Patient-reported outcome measurement (PROM) plays an increasingly important role in palliative care. A variety of measures exists and is used in clinical care, audit and research. However, little is known about professionals' views using these measures. The aim of this study is to describe the use and experiences of palliative care professionals with outcome measures.</p> <p>Methods</p> <p>A web-based online survey was conducted in Europe and Africa. Professionals working in clinical care, audit and research in palliative care were invited to the survey via national palliative care associations and various databases. Invitation e-mails were sent with a link to the questionnaire.</p> <p>Results</p> <p>Overall participation rate 42% (663/1592), overall completion rate 59% (392/663). The majority of respondents were female (63.4%), mean age 46 years (SD 9). 68.1% respondents from Europe and 73.3% from Africa had experiences with outcome measures in palliative care. Non-users reported time constraints, burden, lack of training and guidance as main reasons. In clinical care/audit, assessment of patients' situation, monitoring changes and evaluation of services were main reasons for use. Choice of OMs for research was influenced by validity of the instrument in palliative care and comparability with international literature. Main problems were related to patient characteristics, staff, and outcome measures. Participants expressed the need for more guidance and training in the use of PROMs.</p> <p>Conclusions</p> <p>Professionals need more support for the use and implementation of PROMs in clinical practice and research through training and guidance in order to improve patient care.</p

    Administration and Probate Act Amendment Act, 1970, No. 4

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    Context. As the European population ages and the number of cancer deaths annually increases, there is an urgent requirement to provide high-quality, effective care. The measurement of outcomes in advanced disease is complex, and to conduct comparative research and meta-analyses, appropriate tool selection is essential. Objectives. This study aimed to identify the outcome tools currently in use in end-of-life care (both clinically and for research) across Europe and investigate the preferred features of outcome tools from the perspective of those who select and apply them. Methods. A pan-European Internet-based survey of tool users was conducted in research and clinical populations. Respondents were asked to identify the tools they are using and describe ideal features of the measures. The study was conducted in accordance with guidance for best practice in web-based research. Results. Of the 311 participants who completed a survey, 99 tools in clinical care and audit, and 94 in research, were cited by less than 10 participants. Further data revealed that respondents require the number of potential tools to be rationalized and that brief tools are favored. Conclusion. The selection of valid and appropriate tools for palliative care populations requires expert guidance and support to ensure that clinicians and researchers are collecting data that have validity and potential for comparison within and between populations and countries. J Pain Symptom Manage 2011;42:493-500. (C) 2011 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved

    Critical attitudes and beliefs towards guidelines amongst palliative care professionals - results from a national survey

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    BACKGROUND Little is known about palliative care professionals' attitudes towards guidelines. In 2015, the German Association for Palliative Medicine (DGP) published an evidence based guideline for palliative care in adults with incurable cancer. Before publication we conducted a national survey among members of the DGP to detect possible barriers and facilitators for its implementation. The aim of the present publication was to evaluate critical attitudes and beliefs which could hinder the effective implementation of the new guideline and to evaluate differences within professional groups and medical specialisations. METHODS This web-based online survey was addressed to all members of the DGP in summer 2014. Twenty-one questions concerning attitudes and beliefs towards guidelines were a priori developed to represent the following topics: scepticism regarding the quality of guidelines, doubts about the implementation of guidelines, restrictions in treatment options through guidelines, discrepancy between palliative care values and guidelines. Differences within professions and specialisations were tested using Kruskal-Wallis tests. RESULTS All 4.786 members with known email address were invited, 1.181 followed the link, 1.138 began to answer the questionnaire and 1.031 completed the questionnaire. More than half of participating members were physicians and one third nurses. Scepticism regarding the quality of existing guidelines was high (range 12.8-73.2%). Doubts regarding practical aspects of guidelines were less prevalent but still high (range 21.8-57.6%). About one third (range 5.4-31.4%) think that guidelines restrict their treatment options. In addition, 38.8% believed that guidelines are a kind of cookbook and restrict the flexibility of individual patient care. The majority saw no or little discrepancy between palliative care values and guidelines (range 68.4-82.6%). There were relatively small but significant differences between professions and specialisations. CONCLUSION The person-centred and individual approach of palliative care does not seem to contradict the acceptance of guidelines. Main barriers were related to scepticism regarding the quality of guidelines and the implementation of guidelines in general
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