540 research outputs found
Two fast X-ray transients in archival Chandra data
We present the discovery of two new X-ray transients in archival Chandra
data. The first transient, XRT 110103, occurred in January 2011 and shows a
sharp rise of at least three orders of magnitude in count rate in less than 10
s, a flat peak for about 20 s and decays by two orders of magnitude in the next
60 s. We find no optical or infrared counterpart to this event in preexisting
survey data or in an observation taken by the SIRIUS instrument at the Infrared
Survey Facility 2.1 yr after the transient, providing limiting magnitudes of
J>18.1, H>17.6 and Ks>16.3. This event shows similarities to the transient
previously reported in Jonker et al. which was interpreted as the possible
tidal disruption of a white dwarf by an intermediate mass black hole. We
discuss the possibility that these transients originate from the same type of
event. If we assume these events are related a rough estimate of the rates
gives 1.4*10^5 per year over the whole sky with a peak 0.3-7 keV X-ray flux
greater than 2*10^-10 erg cm^-2 s^-1 . The second transient, XRT 120830,
occurred in August 2012 and shows a rise of at least three orders of magnitude
in count rate and a subsequent decay of around one order of magnitude all
within 10 s, followed by a slower quasi-exponential decay over the remaining 30
ks of the observation. We detect a likely infrared counterpart with magnitudes
J=16.70+/-0.06, H=15.92+/-0.04 and Ks=15.37+/-0.06 which shows an average
proper motion of 74+/-19 milliarcsec per year compared to archival 2MASS
observations. The JHKs magnitudes, proper motion and X-ray flux of XRT 120830
are consistent with a bright flare from a nearby late M or early L dwarf.Comment: Accepted for publication in MNRAS, 6 pages, 5 figure
ShortNotice and Unannounced Survey Methods: Literature review
The Commission’s role is to lead and coordinate national improvements in the safety and quality of health care. The Commission works in partnership with the Australian Government, state and territory governments and the private sector to achieve a safe and high -qu ality, sustainable health system. In doing so, the Commission also works closely with patients, carers, clinicians, managers, policymakers and healthcare organisations. The Commission is responsible under the National Health Reform Act 2011 for the formul ation of standards relating to health care safety and quality matters and for formulating and coordinating national models of accreditation for health service organisations. The Commission developed the National Safety and Quality Health Service (NSQHS) Standards in consultation with the Australian Government , state and territory governments, technical experts and other stakeholders. They aim to protect the public from harm and to improve the quality of health service provision. To become accredited, health service organisations must pass assessments to show they have implemented the NSQHS Standards. The assessments are conducted by independent accrediting agencies, approved by the Commission, as part of the AHSSQA Scheme. However, state and territory regulators and chief executives of health service organisations have raised concerns about several aspects of the accreditation process
Attestation by Governing Bodies: Literature review
Preface This preface was written by the Australian Commission on Safety and Quality in Health Care (the Commission) to provide context and background to the report which follows, Attestation by Governing Bodies: Literature review. The Commission contracted the University of Technology Sydney (UTS) to prepare the literature review, as part of the review of the Australian Health Service Safety and Quality Accreditation (AHSSQA) Scheme. Background The Commission’s role is to lead and coordinate national improvements in the safety and quality of health care. The Commission works in partnership with the Australian Government, state and territory governments and the private sector to achieve a safe and high-quality, sustainable health system. In doing so, the Commission also works closely with patients, carers, clinicians, managers, policymakers and healthcare organisations. The Commission is responsible under the National Health Reform Act 2011 for the formulation of standards relating to healthcare safety and quality matters and for formulating and coordinating national models of accreditation for health service organisations. The Commission developed the National Safety and Quality Health Service (NSQHS) Standards in consultation with the Australian Government, state and territory governments, technical experts and stakeholders. They aim to protect the public from harm and to improve the quality of health service provision. To become accredited, health service organisations must pass assessments to show they have implemented the NSQHS Standards. The assessments are conducted by independent accrediting agencies approved by the Commission as part of the AHSSQA Scheme. However, state and territory regulators and chief executives of health service organisations have raised concerns about several aspects of the accreditation process. The Commission is undertaking a review to update and improve the accreditation process. In May 2017, the Commission contracted four literature reviews to provide an evidence base to inform the Commission’s review of the AHSSQA Scheme. The reviews explored the potential use of the following methods to improve the veracity of health service organisations: • Attestation by a governing body • Short-notice and unannounced surveys • Patient journey and tracer methodologies • Safety culture assessment. The report that follows this preface presents the findings of a literature review that explored the potential use of attestation by governing bodies during accreditation of health service organisations. Key findings The report on attestation by governing bodies includes a definition of attestation, a review of the evidence of the effectiveness of attestation by governing bodies as part of accreditation in healthcare, and examples of the use of attestation in practice
Patient Journey and Tracer Methodologies: Literature review
Preface This preface was written by the Australian Commission on Safety and Quality in Health Care (the Commission) to provide context and background to the report which follows, Patient Journey and Tracer Methodologies: Literature review. The Commission contracted the University of Technology Sydney (UTS) to prepare the literature review, as part of the review of the Australian Health Service Safety and Quality Accreditation (AHSSQA) Scheme. Background The Commission’s role is to lead and coordinate national improvements in the safety and quality of health care. The Commission works in partnership with the Australian Government, state and territory governments and the private sector to achieve a safe and high-quality, sustainable health system. In doing so, the Commission also works closely with patients, carers, clinicians, managers, policymakers and healthcare organisations. The Commission developed the National Safety and Quality Health Service (NSQHS) Standards in consultation with the Australian Government, state and territory governments, technical experts and stakeholders. They aim to protect the public from harm and to improve the quality of health service provision. To become accredited, health service organisations must pass assessments to show they have implemented the NSQHS Standards. The assessments are conducted by independent accrediting agencies, approved by the Commission, as part of the AHSSQA Scheme. However, state and territory regulators and chief executives of health service organisations have raised concerns about several aspects of the accreditation process. The Commission is undertaking a review to update and improve the accreditation process. In May 2017, the Commission contracted four literature reviews to provide an evidence base to inform the Commission’s review of the AHSSQA Scheme. The reviews explored the potential use of the following methods to improve the veracity of health service organisations: • Attestation by a governing body • Short-notice and unannounced surveys • Patient journey and tracer methodologies • Safety culture assessment. The report that follows this preface presents the findings of a literature review that explored the potential use of patient journey and tracer methodologies as part of health service organisation accreditation. Key findings The key findings of the report on patient journey and tracer methodologies (hereafter referred to as ‘patient journey methodologies’) are discussed according to the evidence of its effectiveness and considerations for its use in the AHSSQA Scheme
Open population maximum likelihood spatial capture-recapture
Funding: Part-funded by UK EPSRC grant EP/K041061/1 (DB); Richard Glennie was funded by the Carnegie Trust.Open population capture‐recapture models are widely used to estimate population demographics and abundance over time. Bayesian methods exist to incorporate open population modeling with spatial capture‐recapture (SCR), allowing for estimation of the effective area sampled and population density. Here, open population SCR is formulated as a hidden Markov model (HMM), allowing inference by maximum likelihood for both Cormack‐Jolly‐Seber and Jolly‐Seber models, with and without activity center movement. The method is applied to a 12‐year survey of male jaguars (Panthera onca) in the Cockscomb Basin Wildlife Sanctuary, Belize, to estimate survival probability and population abundance over time. For this application, inference is shown to be biased when assuming activity centers are fixed over time, while including a model for activity center movement provides negligible bias and nominal confidence interval coverage, as demonstrated by a simulation study. The HMM approach is compared with Bayesian data augmentation and closed population models for this application. The method is substantially more computationally efficient than the Bayesian approach and provides a lower root‐mean‐square error in predicting population density compared to closed population models.PostprintPeer reviewe
Cytotoxic CD4+ T cells in patients with B cell chronic lymphocytic leukemia kill via a perforin-mediated pathway
Background and Objectives: B-cell chronic lymphocytic leukemia (B-CLL) is a clonal expansion of CD5+B cells that accumulate due to their uncontrolled growth and resistance
to apoptosis. We have previously shown that up to 50% of blood CD4+ T cells in BCLL patients have a cytotoxicity-related CD28-CD57+ phenotype and high content of both granzyme B and perforin (PF). In this study we investigate the cytotoxic potential of these cells against autologous B-CLL cells.
Design and Methods: Blood CD4+ or CD8+ T cells were positively isolated from B-CLL patients and cultured under a range of conditions with autologous purified B-CLL cells and with bispecific [anti-CD3 x anti-CD19] antibodies. Apoptosis of labeled B-CLL cells was assessed using the change of mitochondrial membrane potential with the fluorescent dye DiOC6 and confirmed by annexin V binding.
Results: There was time- and dose-dependent killing of B-CLL cells by both CD8+ and CD4+ T cells and this ranged from 6.6 - 68.0% for CD4+ cells and 6.4 - 57.8% for CD8+
cells. Almost complete inhibition by concanamycin A suggests that CD4+ T cells like CD8+ T cells induced apoptosis through a perforin-mediated pathway, but not via Fas/FasL (as indicated by lack of blocking with brefeldin A), tumor necrosis factor or TRAIL.
Interpretation and Conclusions: This study shows that blood CD4+PF+ T cells enriched in B-CLL patients, are able to kill autologous B-CLL cells ex vivo, through bispecific antibodies via a perforin mediated mechanism
Dynamic ductile to brittle transition in a one-dimensional model of viscoplasticity
We study two closely related, nonlinear models of a viscoplastic solid. These
models capture essential features of plasticity over a wide range of strain
rates and applied stresses. They exhibit inelastic strain relaxation and steady
flow above a well defined yield stress. In this paper, we describe a first step
in exploring the implications of these models for theories of fracture and
related phenomena. We consider a one dimensional problem of decohesion from a
substrate of a membrane that obeys the viscoplastic constitutive equations that
we have constructed. We find that, quite generally, when the yield stress
becomes smaller than some threshold value, the energy required for steady
decohesion becomes a non-monotonic function of the decohesion speed. As a
consequence, steady state decohesion at certain speeds becomes unstable. We
believe that these results are relevant to understanding the ductile to brittle
transition as well as fracture stability.Comment: 10 pages, REVTeX, 12 postscript figure
Deep Learning Hydrodynamic Forecasting for Flooded Region Assessment in Near-Real-Time (DL Hydro-FRAN)
Hydrodynamic flood modeling improves hydrologic and hydraulic prediction of
storm events. However, the computationally intensive numerical solutions
required for high-resolution hydrodynamics have historically prevented their
implementation in near-real-time flood forecasting. This study examines whether
several Deep Neural Network (DNN) architectures are suitable for optimizing
hydrodynamic flood models. Several pluvial flooding events were simulated in a
low-relief high-resolution urban environment using a 2D HEC-RAS hydrodynamic
model. These simulations were assembled into a training set for the DNNs, which
were then used to forecast flooding depths and velocities. The DNNs' forecasts
were compared to the hydrodynamic flood models, and showed good agreement, with
a median RMSE of around 2 mm for cell flooding depths in the study area. The
DNNs also improved forecast computation time significantly, with the DNNs
providing forecasts between 34.2 and 72.4 times faster than conventional
hydrodynamic models. The study area showed little change between HEC-RAS' Full
Momentum Equations and Diffusion Equations, however, important numerical
stability considerations were discovered that impact equation selection and DNN
architecture configuration. Overall, the results from this study show that DNNs
can greatly optimize hydrodynamic flood modeling, and enable near-real-time
hydrodynamic flood forecasting.Comment: 21 pages, 8 figure
Sociology’s missed opportunity: John Stuart-Glennie’s lost theory of the moral revolution, also known as the axial age
In 1873, 75 years before Karl Jaspers published his theory of the Axial Age in 1949, unknown to Jaspers and to contemporary scholars today, Scottish folklorist John Stuart Stuart-Glennie elaborated the first fully developed and nuanced theory of what he termed “the Moral Revolution” to characterize the historical shift emerging roughly around 600 BCE in a variety of civilizations, most notably ancient China, India, Judaism, and Greece, as part of a broader critical philosophy of history. He continued to write on the idea over decades in books and articles and also presented his ideas to the fledgling Sociological Society of London in 1905, which were published the following year in the volume Sociological Papers, Volume 2. This article discusses Stuart-Glennie’s ideas on the moral revolution in the context of his philosophy of history, including what he termed “panzooinism”; ideas with implications for contemporary debates in theory, comparative history, and sociology of religion. It shows why he should be acknowledged as the originator of the theory now known as the axial age, and also now be included as a significant sociologist in the movement toward the establishment of sociology
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