2,321 research outputs found
Determination of the X-ray reflection emissivity profile of 1H 0707-495
When considering the X-ray spectrum resulting from the reflection off the
surface of accretion discs of AGN, it is necessary to account for the variation
in reflected flux over the disc, i.e. the emissivity profile. This will depend
on factors including the location and geometry of the X-ray source and the disc
characteristics. We directly obtain the emissivity profile of the disc from the
observed spectrum by considering the reflection component as the sum of
contributions from successive radii in the disc and fitting to find the
relative weightings of these components in a relativistically-broadened
emission line. This method has successfully recovered known emissivity profiles
from synthetic spectra and is applied to XMM-Newton spectra of the Narrow Line
Seyfert 1 galaxy 1H 0707-495. The data imply a twice-broken power law form of
the emissivity law with a steep profile in the inner regions of the disc (index
7.8) and then a flat region between 5.6rg and 34.8rg before tending to a
constant index of 3.3 over the outer regions of the disc. The form of the
observed emissivity profile is consistent with theoretical predictions, thus
reinforcing the reflection interpretation.Comment: 9 pages, 10 figures. Accepted for publication in MNRA
Degrees of change: between and within population variation in thermal reaction norms of phenology in a viviparous lizard
As the earth warms, populations will be faced with novel environments to which they may not be adapted. In the short term, populations can be buffered against the negative effects, or maximize the beneficial effects, of such environmental change via phenotypic plasticity and, in the longer term, via adaptive evolution. However, the extent and direction of these population-level responses will be dependent on the degree to which responses vary among the individuals within them (i.e., within population variation in plasticity), which is, itself, likely to vary among populations. Despite this, we have estimates of among-individual variation in plastic responses across multiple populations for only a few systems. This lack of data limits our ability to predict the consequences of environmental change for population and species persistence accurately. Here, we utilized a 16-yr data set from climatically distinct populations of the viviparous skink Niveoscincus ocellatus tracking over 1,200 litters from more than 600 females from each population to examine inter- and intrapopulation variability in the response of parturition date to environmental temperature. We found that these populations share a common population-mean reaction norm but differ in the degree to which reaction norms vary among individuals. These results suggest that even where populations share a common mean-level response, we cannot assume that they will be affected similarly by altered environmental conditions. If we are to assess how changing climates will impact species and populations accurately, we require estimates of how plastic responses vary both among and within populations.publishedVersio
Elite male Flat jockeys display lower bone density and lower resting metabolic rate than their female counterparts: implications for athlete welfare
To test the hypothesis that daily weight-making is more problematic to health in male compared with female jockeys, we compared the bone-density and resting metabolic rate (RMR) in weight-matched male and female Flat-jockeys. RMR (kcal.kg-1 lean mass) was lower in males compared with females as well as lower bone-density Z-scores at the hip and lumbar spine. Data suggest the lifestyle of male jockeysâ compromise health more severely than females, possibly due to making-weight more frequently
X-ray iron line variability for the model of an orbiting flare above a black hole accretion disc
The broad X-ray iron line, detected in many active galactic nuclei, is likely
to be produced by fluorescence from the X-ray illuminated central parts of an
accretion disc close to a supermassive black hole. The time-averaged shape of
the line can be explained most naturally by a combination of special and
general relativistic effects. Such line profiles contain information about the
black hole spin and the accretion disc as well as the geometry of the emitting
region and may help to test general relativity in the strong gravity regime. In
this paper we embark on the computation of the temporal response of the line to
the illuminating flux. Previous studies concentrated on the calculation of
reverberation signatures from static sources illuminating the disc. In this
paper we focus on the more physically justified case of flares located above
the accretion disc and corotating with it. We compute the time dependent iron
line taking into account all general relativistic effects and show that its
shape is of very complex nature, and also present light curves accompanying the
iron line variability. We suggest that future X-ray satellites like XMM or
Constellation-X may be capable of detecting features present in the computed
reverberation maps.Comment: Accepted for publication in MNRAS, 11 pages, 12 figure
Automated detection and staging of malaria parasites from cytological smears using convolutional neural networks
Microscopic examination of blood smears remains the gold standard for laboratory inspection and diagnosis of malaria. Smear inspection is, however, time-consuming and dependent on trained microscopists with results varying in accuracy. We sought to develop an automated image analysis method to improve accuracy and standardization of smear inspection that retains capacity for expert confirmation and image archiving. Here, we present a machine learning method that achieves red blood cell (RBC) detection, differentiation between infected/uninfected cells, and parasite life stage categorization from unprocessed, heterogeneous smear images. Based on a pretrained Faster Region-Based Convolutional Neural Networks (R-CNN) model for RBC detection, our model performs accurately, with an average precision of 0.99 at an intersection-over-union threshold of 0.5. Application of a residual neural network-50 model to infected cells also performs accurately, with an area under the receiver operating characteristic curve of 0.98. Finally, combining our method with a regression model successfully recapitulates intraerythrocytic developmental cycle with accurate lifecycle stage categorization. Combined with a mobile-friendly web-based interface, called PlasmoCount, our method permits rapid navigation through and review of results for quality assurance. By standardizing assessment of Giemsa smears, our method markedly improves inspection reproducibility and presents a realistic route to both routine lab and future field-based automated malaria diagnosis
Early Psychosis Intervention-Spreading Evidence-based Treatment (EPI-SET) : Protocol for an effectiveness-implementation study of a structured model of care for psychosis in youth and emerging adults
Introduction While early psychosis intervention (EPI) has proliferated in recent years amid evidence of its effectiveness, programmes often struggle to deliver consistent, recovery-based care. NAVIGATE is a manualised model of EPI with demonstrated effectiveness consisting of four components: individualised medication management, individual resiliency training, supported employment and education and family education. We aim to implement NAVIGATE in geographically diverse EPI programmes in Ontario, Canada, evaluating implementation and its effect on fidelity to the EPI model, as well as individual-level outcomes (patient/family member-reported and interviewer-rated), system-level outcomes (captured in provincial administrative databases) and engagement of participants with lived experience. Methods and analysis This is a multisite, non-randomised pragmatic hybrid effectiveness-implementation type III mixed methods study coordinated at the Centre for Addiction and Mental Health (CAMH) in Toronto. Implementation is supported by the Provincial System Support Program, a CAMH-based programme with provincial offices across Ontario, and Extension of Community Healthcare Outcomes Ontario Mental Health at CAMH and the University of Toronto. The primary outcome is fidelity to the EPI model as measured using the First Episode Psychosis Services-Fidelity Scale. Four hundred participants in the EPI programmes will be recruited and followed using both individual-level assessments and health administrative data for 2 years following NAVIGATE initiation. People with lived experience will be engaged in all aspects of the project, including through youth and family advisory committees. Ethics and dissemination Research ethics board approval has been obtained from CAMH and institutions overseeing the local EPI programmes. Study findings will be reported in scientific journal articles and shared with key stakeholders including youth, family members, programme staff and policymakers. Trial registration number NCT03919760; Pre-results
The Importance of Ethics and Ethical Leadership in the Accounting Profession
The emergence of the twenty-first century was plagued with extensive, evasive and disheartening leadership failures. Despite the accounting professionâs standards of professional ethics, it was also tainted with ethical leadership indiscretions during this era. In response to these ethical leadership failings, renewed interest in developing accounting professionals with strong ethical principles and ethical leadership behaviors has emerged. In many firms training and development of ethical behavior is now at the forefront of the firmâs communications and professional development efforts. The question remains however, can the profession instill in its members the importance of ethical conduct? Can ethical leaders be developed that model and monitor ethical behavior? In response to the call for leaders who are ethical and moral, this research examined a model that examines ethical leadership and its impact on leader effectiveness for leaders within the accounting industry. The analysis shows that ethical and transformational leadership make incremental independent contributions in explaining leader effectiveness. The study comments on how the findings that ethically and morally focused leaders may impact the accounting profession and restore an industry tarnished with accusations of unethical behavior to one that regains its original prominence based on consistent, moral, ethical, and effective leaders
The life cycle of stars and their planets from the high energy perspective
One of the key research themes identified by the Astro2020 decadal survey is
Worlds and Suns in Context. The Advanced X-ray Imaging Satellite (AXIS) is a
proposed NASA APEX mission that will become the prime high-energy instrument
for studying star-planet connections from birth to death. This work explores
the major advances in this broad domain of research that will be enabled by the
AXIS mission, through X-ray observations of stars in clusters spanning a broad
range of ages, flaring M-dwarf stars known to host exoplanets, and young stars
exhibiting accretion interactions with their protoplanetary disks. In addition,
we explore the ability of AXIS to use planetary nebulae, white dwarfs, and the
Solar System to constrain important physical processes from the microscopic
(e.g., charge exchange) to the macroscopic (e.g., stellar wind interactions
with the surrounding interstellar medium).Comment: This White Paper is part of a series commissioned for the AXIS Probe
Concept Missio
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of
continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a
fully coherent search, based on matched filtering, which uses the position and rotational parameters
obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto-
noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch
between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have
been developed, allowing a fully coherent search for gravitational waves from known pulsars over a
fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of
11 pulsars using data from Advanced LIGOâs first observing run. Although we have found several initial
outliers, further studies show no significant evidence for the presence of a gravitational wave signal.
Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of
the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for
the first time. For an additional 3 targets, the median upper limit across the search bands is below the
spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried
out so far
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