686 research outputs found
Star formation in infrared bright and infrared faint starburst interacting galaxies
Short wavelength IUE spectra of Arp 248b and UGC 8315N are combined with optical spectra and interpreted using a combination of spectrum synthesis and spectral diagnostics to place constraints on the massive star populations of the central regions of these galaxies and to deduce information about the star formation histories in the last 10(exp 8) years. The authors find that both galaxies have substantial fractions of their optical light coming from massive stars and that Arp 248b may be dominated in the UV by WR stars. The UV spectra are dominated by radiation from evolved massive stars and the authors place and age on the burst in Arp 248b of a few tens of millions of years
Revisiting the equity debate in COVID-19 : ICU is no panacea
Copyright information No commercial re-use. See rights and permissions. Published by BMJ. This article is made freely available for use in accordance with BMJ's website terms and conditions for the duration of the covid-19 pandemic or until otherwise determined by BMJ. You may use, download and print the article for any lawful, non-commercial purpose (including text and data mining) provided that all copyright notices and trade marks are retained. https://bmj.com/coronavirus/usagePeer reviewedPostprin
Evaluation of a compact multi-contrast and multi-resolution X-ray phase contrast edge illumination system for small animal imaging
PURPOSE: In this work the performance of a compact multi-resolution and multi-contrast X-ray phase system based on edge illumination is investigated. It has been designed for small animal imaging and with a limited footprint for ease of deployment in laboratories. METHODS: The presented edge illumination system is based on a compact microfocus tungsten X-ray source combined with a at panel detector. The source has a maximum output of 10 W when the minimum spot size of about 15 µm is used. The system has an overall length of 70 cm. A new double sample mask design, obtained by arranging both skipped and non-skipped configurations on the same structure, provides dual resolution capability. To test the system, we carried out CT scans of a plastic phantom with different source settings using both single-image and multi-image acquisition schemes at different spatial resolutions. In addition, CT scans of an ex-vivo mouse specimen were acquired at the best identified working conditions to demonstrate the application of the presented system to small animal imaging. RESULTS: We found this system delivers good image quality, allowing for an efficient material separation and improving detail visibility in small animals thanks to the higher signal-to-noise ratio (SNR) of phase contrast with respect to conventional attenuation contrast. The system offers high versatility in terms of spatial resolution thanks to the double sample mask design integrated into a single scanner. The availability of both multi and single image acquisition schemes coupled with their dedicated retrieval algorithms, allows different working modes which can be selected based on user preference. Multi-image acquisition provides quantitative separation of the real and imaginary part of the refractive index, however it requires a long scanning time. On the other hand, the single image approach delivers the best material separation and image quality at all the investigated source settings with a shorter scanning time but at the cost of quantitativeness. Finally, we also observed that the single image approach combined with a high-power X-ray source may result in a fast acquisition protocol compatible with in-vivo imaging
Weight Changes Post-Phentermine Use
Purpose: Evaluate weight maintenance in subjects who lost weight while taking phentermine (PTM). Methods: This study was conducted by utilizing a validated survey to collect self-reported data about weight changes post-PTM use. The survey was sent to 19,986 email addresses of current and former patients of a PTM-based outpatient clinic, located in Chicago, IL; 546 participants completed the survey. Results were analyzed using a variety of techniques. Results: At the time of the survey, 42% of responders maintained all the weight lost while on PTM, and 25.2% had maintained a weight loss of at least 10% of their body weight. The average weight lost and maintained at the time of the survey was 3.75% ± 13.8% of body weight or 8.74 lbs ± 27.45 lbs. Nineteen responders had no net weight change. Fifty-nine responders reported a net weight gain, ranging from 2 to 70 lbs with a mean net weight gain of 16.07 lbs ± 13.87 lbs. The duration of time since discontinuing PTM use had a significant correlation with weight maintenance: r = 0.340, p value = .000. There was no significant correlation between duration of time using PTM and weight maintenance. No correlations were identified between education, income, or ethnicity and weight maintenance. A correlation was identified between weight maintenance and current exercise level: r = 0.218, p value = .000. Conclusions: Although more research is needed, with the results of this study, the investigators suggest that post-PTM use, weight regain is not significantly higher than weight regain through other weight loss programs. In order to achieve long-term weight loss maintenance, it may behoove patients to receive professional guidance about behavior modifications to maintain weight lost, particularly related to exercise and dietary changes. The investigators of this study suggest greater emphasis on behavior modification in patients taking PTM is indicated
HDArray: Parallel Array Interface for Distributed Heterogeneous Devices
Heterogeneous clusters with nodes containing one or more accelerators, such as GPUs, have become common. While MPI provides a mechanism and management of interaddress space communication, and OpenCL provides a way to manage computation and communication within a process with access to heterogeneous computational resources, programmers are forced to write hybrid programs that manage the interaction of both of these systems. This paper describes an array programming interface that provides users with automatic or manual distributions of data and work. Using the distribution and information about what data is used and defined by kernels, communication among processes and among devices in a process is performed automatically. The interface provides a unified programming model to the user, thus simplifying program development
Three dimensional numerical relativity: the evolution of black holes
We report on a new 3D numerical code designed to solve the Einstein equations
for general vacuum spacetimes. This code is based on the standard 3+1 approach
using cartesian coordinates. We discuss the numerical techniques used in
developing this code, and its performance on massively parallel and vector
supercomputers. As a test case, we present evolutions for the first 3D black
hole spacetimes. We identify a number of difficulties in evolving 3D black
holes and suggest approaches to overcome them. We show how special treatment of
the conformal factor can lead to more accurate evolution, and discuss
techniques we developed to handle black hole spacetimes in the absence of
symmetries. Many different slicing conditions are tested, including geodesic,
maximal, and various algebraic conditions on the lapse. With current
resolutions, limited by computer memory sizes, we show that with certain lapse
conditions we can evolve the black hole to about , where is the
black hole mass. Comparisons are made with results obtained by evolving
spherical initial black hole data sets with a 1D spherically symmetric code. We
also demonstrate that an ``apparent horizon locking shift'' can be used to
prevent the development of large gradients in the metric functions that result
from singularity avoiding time slicings. We compute the mass of the apparent
horizon in these spacetimes, and find that in many cases it can be conserved to
within about 5\% throughout the evolution with our techniques and current
resolution.Comment: 35 pages, LaTeX with RevTeX 3.0 macros. 27 postscript figures taking
7 MB of space, uuencoded and gz-compressed into a 2MB uufile. Also available
at http://jean-luc.ncsa.uiuc.edu/Papers/ and mpeg simulations at
http://jean-luc.ncsa.uiuc.edu/Movies/ Submitted to Physical Review
Захист від недобросовісної конкуренції у медичній сфері: проблеми правововго регулювання
Кожна людина має право на здорові умови життя, але напевно ще жодному не вдавалось уникнути звернень до лікарень, аптек, та інших організацій медичної сфери. Метою даної статті є дослідження захисту від недобросовісної конкуренції у медичній сфері в Україні та інших країнах та розроблення наукових рекомендацій щодо вдосконалення українського законодавства щодо врегулювання відносин щодо здійснення господарювання в медичній сфері
Center for Research on the Education of Students Placed at Risk: Report #44
The Center for Research on the Education of Students Placed at Risk (CRESPAR) was established in 1994 and continued until 2004. It was a collaboration between Johns Hopkins University and Howard University. CRESPAR’s mission was to conduct research, development, evaluation, and dissemination of replicable strategies designed to transform schooling for students who were placed at risk due to inadequate institutional responses to such factors as poverty, ethnic minority status, and non-English-speaking home background.The purpose of this study was to gain descriptive insights into the routines, practices, perceptions, and interactions that constitute the everyday ecology of classrooms serving African American children from low-income backgrounds.Office of Educational Research and Improvement (OERI), U.S. Department of Education (R-117-D40005
A Preliminary Investigation into the Use of Edge Illumination X-ray Phase Contrast Micro-CT for Preclinical Imaging
Purpose: To enable a preliminary assessment of the suitability of edge illumination (EI) x-ray
phase contrast (XPC) micro x-ray computed tomography (micro-CT) to preclinical imaging.
Specifically, to understand how different acquisition schemes and their combination with
dedicated data processing affect contrast-to-noise ratio (CNR) and spatial resolution, while
providing control over scan time and radiation dose delivery.
Procedures: Deceased mice (n = 3) were scanned with an EI XPC micro-CT setup operated
under different settings, leading to scan times between 18 h and 13 min. For the shortest scan,
the entrance dose was measured with a calibrated PTW 23344 ion chamber. Different data
processing methods were applied, retrieving either separate attenuation and phase images, or
hybrid (combined attenuation and phase) images. A quantitative comparison was performed
based on CNR and spatial resolution measurements for a soft tissue interface.
Results: All phase-based images have led to a higher CNR for the considered soft tissue
interface than the attenuation image, independent of scan time. The best relative CNR (a sixfold
increase) was observed in one of the hybrid images. Spatial resolution was found to be
connected to scan time, with a resolution of approximately 20 μm and 60 μm achieved for the
longest and shortest scans, respectively. An entrance dose of approximately 300 mGy was
estimated for the scan performed within 13 min.
Conclusions: Despite their preliminary nature, our results suggest that EI XPC bears potential for
enhancing the utility of preclinical micro-CT, and, pending further research and development,
could ultimately become a valuable technique in this field
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