584 research outputs found

    Dissociative excitation transfer in the reaction of O-2(a(1)Delta(g)) with OH-(H2O)(1,2) clusters.

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    Rate constants for the dissociation of OH-(H2O) and OH-(H2O)(2) by transfer of electronic energy from O-2(a(1)Delta(g)) were measured. Values of 1.8x10(-11) and 2.2x10(-11) cm(3) molecule(-1) s(-1), respectively, at 300 K were derived and temperature dependences were obtained from 300 to 500 K for OH-(H2O) and from 300 to 400 K for OH-(H2O)(2). Dissociative excitation transfer with OH-(H2O) is slightly endothermic and the reaction appears to have a positive temperature dependence, but barely outside the uncertainty range. In contrast, the reaction of OH-(H2O)(2) is exothermic and appears to have a negative temperature dependence. The rate constants are analyzed in terms of unimolecular rate theory, which suggests that the dissociation is prompt and is not affected by collisions with the helium buffer gas

    Formation of Massive Black Holes in Dense Star Clusters. II. IMF and Primordial Mass Segregation

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    A promising mechanism to form intermediate-mass black holes (IMBHs) is the runaway merger in dense star clusters, where main-sequence stars collide and form a very massive star (VMS), which then collapses to a black hole. In this paper we study the effects of primordial mass segregation and the importance of the stellar initial mass function (IMF) on the runaway growth of VMSs using a dynamical Monte Carlo code for N-body systems with N as high as 10^6 stars. Our code now includes an explicit treatment of all stellar collisions. We place special emphasis on the possibility of top-heavy IMFs, as observed in some very young massive clusters. We find that both primordial mass segregation and the shape of the IMF affect the rate of core collapse of star clusters and thus the time of the runaway. When we include primordial mass segregation we generally see a decrease in core collapse time (tcc). Moreover, primordial mass segregation increases the average mass in the core, thus reducing the central relaxation time, which also decreases tcc. The final mass of the VMS formed is always close to \sim 10^-3 of the total cluster mass, in agreement with the previous studies and is reminiscent of the observed correlation between the central black hole mass and the bulge mass of the galaxies. As the degree of primordial mass segregation is increased, the mass of the VMS increases at most by a factor of 3. Flatter IMFs generally increase the average mass in the whole cluster, which increases tcc. For the range of IMFs investigated in this paper, this increase in tcc is to some degree balanced by stellar collisions, which accelerate core collapse. Thus there is no significant change in tcc for the somewhat flatter global IMFs observed in very young massive clusters.Comment: Accepted for publication in Ap

    Studies with Artificial Fever in Experimental Tuberculosis

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    Author Institution: Department of Medical and Surgical Research, Ohio State Universit

    Donor characteristics and the allocation of aid to climate mitigation finance

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    We make use of a panel dataset of 22 donor countries from 1998 to 2009 to examine the links between donor characteristics and the share of overseas development assistance allocated to climate mitigation finance. We find that donors with a larger green domestic budget tend to allocate a smaller portion of overseas aid to mitigation finance (possibly as a result of a competing interest between spending on domestic environmental projects and international climate projects). The opposite holds for donor countries with better institutions (governance) that have ratified the Kyoto Protocol. We also find important discrepancies when comparing the effects of donor characteristics on committed versus disbursed mitigation finance (as a share of aid). For the latter, only commitment to the Kyoto Protocol appears to be of high statistical significance

    Dimensions of safety culture: A systematic review of quantitative, qualitative and mixed methods for assessing safety culture in hospitals

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    Background The study of safety culture and its relationship to patient care have been challenged by variation in definition, dimensionality and methods of assessment. This systematic review aimed to map methods to assess safety culture in hospitals, analyse the prevalence of these methods in the published research literature and examine the dimensions of safety culture captured through these processes. Methods We included studies reporting on quantitative, qualitative and mixed methods to assess safety culture in hospitals. The review was conducted using four academic databases (PubMed, CINAHL, Scopus and Web of Science) with studies from January 2008 to May 2020. A formal quality appraisal was not conducted. Study purpose, type of method and safety culture dimensions were extracted from all studies, coded thematically, and summarised narratively and using descriptive statistics where appropriate. Results A total of 694 studies were included. A third (n=244, 35.2%) had a descriptive or exploratory purpose, 225 (32.4%) tested relationships among variables, 129 (18.6%) evaluated an intervention, while 13.8% (n=96) had a methodological focus. Most studies exclusively used surveys (n=663; 95.5%), with 88 different surveys identified. Only 31 studies (4.5%) used qualitative or mixed methods. Thematic analysis identified 11 themes related to safety culture dimensions across the methods, with € Leadership' being the most common. Qualitative and mixed methods approaches were more likely to identify additional dimensions of safety culture not covered by the 11 themes, including improvisation and contextual pressures. Discussion We assessed the extent to which safety culture dimensions mapped to specific quantitative and qualitative tools and methods of assessing safety culture. No single method or tool appeared to measure all 11 themes of safety culture. Risk of publication bias was high in this review. Future attempts to assess safety culture in hospitals should consider incorporating qualitative methods into survey studies to evaluate this multi-faceted construct

    Communicating risk in active surveillance of localised prostate cancer: A protocol for a qualitative study

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    Introduction One in five men is likely to receive a diagnosis of prostate cancer (PCa) by the age of 85 years. Men diagnosed with low-risk PCa may be eligible for active surveillance (AS) to monitor their cancer to ensure that any changes are discovered and responded to in a timely way. Communication of risk in this context is more complicated than determining a numerical probability of risk, as patients wish to understand the implications of risk on their lives in concrete terms. Our study will examine how risk for PCa is perceived, experienced and communicated by patients using AS with their health professionals, and the implications for treatment and care. Methods and analysis This is a proof of concept study, testing out a multimethod, qualitative approach to data collection in the context of PCa for the first time in Australia. It is being conducted from November 2016 to December 2017 in an Australian university hospital urology clinic. Participants are 10 men with a diagnosis of localised PCa, who are using an AS protocol, and 5 health professionals who work with this patient group (eg, urologists and Pca nurses). Data will be collected using observations of patient consultations with health professionals, patient questionnaires and interviews, and interviews with healthcare professionals. Analysis will be conducted in two stages. First, observational data from consultations will be analysed thematically to encapsulate various dimensions of risk classification and consultation dialogue. Second, interview data will be coded to derive meaning in text and analysed thematically. Overarching themes will represent patient and health professional perspectives of risk communication. Ethics and dissemination Ethical approval for the study has been granted by Macquarie University Human Research Ethics Committee, approval 5201600638. Knowledge translation will be achieved through publications, reports and conference presentations to patients, families, clinicians and researchers

    Relational autonomy in breast diseases care: A qualitative study of contextual and social conditions of patients' capacity for decision-making 17 Psychology and Cognitive Sciences 1701 Psychology

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    Background: A relational approach to autonomy refers to the way in which social conditions and relationships shape a person's self-identity and capacity in decision-making. This article provides an empirical account of how treatment choices for women undergoing breast diseases care are fostered within the dynamics of their relationships with clinicians, family members, and other aspects of their social environment. Methods: This qualitative study recruited ten women undergoing treatment at a breast programme, and eight clinicians supporting their care, in a private teaching hospital in New South Wales, Australia. Fourteen patient-clinician consultation observations and 17 semi-structured interviews were conducted. Schema analysis of interview transcripts were undertaken by a team of researchers and corroborated by observational fieldnotes. Results: Relational identities of patients influenced the rationale for treatment decision-making. Patients drew on supportive resources from family and medical advice from clinicians to progress with treatment goals. While clinicians held much social power over patients as the medical experts, patients highlighted the need for clinicians to earn their trust through demonstrated professionalism. Information exchange created a communicative space for clinicians and patients to negotiate shared values, promoting greater patient ownership of treatment decisions. As treatment progressed, patients' personal experiences of illness and treatment became a source of self-reflection, with a transformative impact on self-confidence and assertiveness. Conclusion: Patients' confidence and self-trust can be fostered by opportunities for communicative engagement and self-reflection over the course of treatment in breast disease, and better integration of their self-identity and social values in treatment decisions
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