2,886 research outputs found
The Opacity of Spiral Galaxy Disks IV: Radial Extinction Profiles from Counts of Distant Galaxies seen through Foreground Disks
Dust extinction can be determined from the number of distant field galaxies
seen through a spiral disk. To calibrate this number for the crowding and
confusion introduced by the foreground image, Gonzalez et al.(1998) and
Holwerda et al. (2005) developed the ``Synthetic Field Method'' (SFM), which
analyses synthetic fields constructed by adding various deep exposures of
unobstructed background fields to the candidate foreground galaxy field.
The advantage of the SFM is that it gives the average opacity for area of
galaxy disk without assumptions about either the distribution of absorbers or
of the disk starlight. However it is limited by low statistics of the surviving
field galaxies, hence the need to combine a larger sample of fields. This paper
presents the first results for a sample of 32 deep HST/WFPC2 archival fields of
29 spirals.
The radial profiles of average dust extinction in spiral galaxies based on
calibrated counts of distant field galaxies is presented here, both for
individual galaxies as well as for composites from our sample. The effects of
inclination, spiral arms and Hubble type on the radial extinction profile are
discussed. (Abbreviated)Comment: 43 pages, 16 figures, 3 tables, accepted for publication in the
Astronomical Journal, (typos, table update, updates abstract
Shotgun Cloning of Transposon Insertions in the Genome of Caenorhabditis elegans
We present a strategy to identify and map large numbers of transposon insertions in
the genome of Caenorhabditis elegans. Our approach makes use of the mutator strain
mut-7, which has germline-transposition activity of the Tc1/mariner family of transposons,
a display protocol to detect new transposon insertions, and the availability of
the genomic sequence of C. elegans. From a pilot insertional mutagenesis screen, we
have obtained 351 new Tc1 transposons inserted in or near 219 predicted C. elegans
genes. The strategy presented provides an approach to isolate insertions of natural
transposable elements in many C. elegans genes and to create a large-scale collection
of C. elegans mutants
The demand for corporate financial reporting: A survey among financial analysts
Abstract:
We examine financial analystsâ views on corporate financial reporting issues by means of a survey among 306 analysts and interviews among 21 analysts and compare their views with that of CFOs. Since CFOs believe that meeting or beating analystsâ forecasts and managing earnings to achieve this benchmark can enhance firm value, examining analystsâ perspectives on these actions improves our understanding on whether CFOsâ beliefs are rational or heuristic. Our findings suggest that CFOsâ beliefs tend to be rational regarding their focus on earnings and their views on earnings management and smoothing. The main reason is that analysts have difficulty in unraveling certain types of earnings management in a specific firm even though they anticipate earnings management in general. Yet, CFOs are heuristic in their optimism about the consequences of managing earnings, which potentially has negative implications for the value of their firm
Reproducibility of coronary artery calcium quantification on dual-source CT and dual-source photon-counting CT:a dynamic phantom study
To systematically compare coronary artery calcium (CAC) quantification between conventional computed tomography (CT) and photon-counting CT (PCCT) at different virtual monoenergetic (monoE) levels for different heart rates. A dynamic (heart rates of 0,ââ75 bpm) anthropomorphic phantom with three calcification densities was scanned using routine clinical CAC protocols with CT and PCCT. In addition to the standard clinical protocol of 70 keV, PCCT images were reconstructed at monoE levels of 72, 74, and 76 keV. CAC was quantified using Agatston, volume, and mass scores. Agatston scores 95% confidence intervals (CI) were calculated and compared between PCCT and CT. Volume and mass scores were compared with physical quantities. For all CAC densities, routine clinical protocol Agatston scores of static CAC were higher for PCCT compared to CT. Atâ<â60 bpm, Agatston scores at 74 and 76 keV reconstructions were reproducible (overlapping CI) for PCCT and CT. Increased heart rates yielded different Agatston scores for PCCT in comparison with CT, for all monoE levels. Low density CAC volume scores showed the largest deviation from physical volume, with mean deviations of 59% and 77% for CT and PCCT, respectively. Overall, mass scores underestimated physical mass by 10%, 38%, and 59% for low, medium, and high density CAC, respectively. PCCT allows for reproducible Agatston scores for dynamic CAC (<â60 bpm) when reconstructed at monoE levels of 74 or 76 keV, regardless of CAC density. Deviations from physical volume and mass were, in general, large for both CT and PCCT
Experiences of case managers in providing person-centered and integrated care based on the Chronic Care Model:A qualitative study on embrace
<div><p>Background</p><p>Due to the rise in the number of older adults within the population, healthcare demands are changing drastically, all while healthcare expenditure continues to grow. Person-centered and integrated-care models are used to support the redesigning the provision of care and support. Little is known, however, about how redesigning healthcare delivery affects the professionals involved.</p><p>Objectives</p><p>To explore how district nurses and social workers experience their new professional roles as case managers within Embrace, a person-centered and integrated-care service for community-living older adults.</p><p>Methods</p><p>We performed a qualitative study consisting of in-depth interviews with case managers (district nurses, n = 6; social workers, n = 5), using a topic-based interview guide. Audiotaped interviews were transcribed verbatim and analyzed using qualitative content analysis.</p><p>Results</p><p>The experiences of the case managers involved four major themes: 1) the changing relationship with older adults, 2) establishing the case-manager role, 3) the case managerâs toolkit, and 4) the benefits of case management. Within these four themes, subthemes addressed the shift to a person-centered approach, building a relationship of trust, the process of case management, knowledge and experience, competencies of and requirements for case managers, and the differences in professional background.</p><p>Discussion</p><p>We found that this major change in role was experienced as a learning process, one that provided opportunities for personal and professional growth. Case managers felt that they were able to make a difference, and found their new roles satisfying and challenging, although stressful at times. Ongoing training and support were found to be a prerequisite in helping to shift the focus towards person-centered and integrated care.</p></div
De Berckepoort in Dordrecht; De praktische toepassing van bouwhistorisch onderzoek (ontleding) in het ontwerpproces
No abstract available[No abstract available
UNAMBIGUOUS EVALUATIONS OF BIDECIC JACOBI AND JACOBSTHAL SUMS
Abstract For a class of primes p = 1 (mod 20) for which 2 is a quintic nonresidue, unambiguous evaluations of parameters of bidecic Jacobi and Jacobsthal sums (modp
Control and Local Measurement of the Spin Chemical Potential in a Magnetic Insulator
The spin chemical potential characterizes the tendency of spins to diffuse.
Probing the spin chemical potential could provide insight into materials such
as magnetic insulators and spin liquids and aid optimization of spintronic
devices. Here, we introduce single-spin magnetometry as a generic platform for
non-perturbative, nanoscale characterization of spin chemical potentials. We
use this platform to investigate magnons in a magnetic insulator, surprisingly
finding that the magnon chemical potential can be efficiently controlled by
driving the system's ferromagnetic resonance. We introduce a symmetry-based
two-fluid theory describing the underlying magnon processes, realize the first
experimental determination of the local thermomagnonic torque, and illustrate
the detection sensitivity using electrically controlled spin injection. Our
results open the way for nanoscale control and imaging of spin transport in
mesoscopic spin systems.Comment: 18 pages, 4 figure
XTE J1701-462 and its Implications for the Nature of Subclasses in Low-Magnetic-Field Neutron Star Low-Mass X-Ray Binaries
We report on an analysis of RXTE data of the transient neutron star low-mass
X-ray binary (NS-LMXB) XTE J1701-462, obtained during its 2006-2007 outburst.
The X-ray properties of the source changed between those of various types of
NS-LMXB subclasses. At high luminosities the source switched between two types
of Z source behavior and at low luminosities we observed a transition from Z
source to atoll source behavior. These transitions between subclasses primarily
manifest themselves as changes in the shapes of the tracks in X-ray color-color
and hardness-intensity diagrams, but they are accompanied by changes in the kHz
quasi-periodic oscillations, broad-band variability, burst behavior, and/or
X-ray spectra. We find that the low-energy X-ray flux is a good parameter to
track the gradual evolution of the tracks in color-color and hardness-intensity
diagrams, allowing us to resolve the evolution of the source in greater detail
than before and relate the observed properties to other NS-LMXBs. We further
find that during the transition from Z to atoll, characteristic behavior known
as the atoll upper banana can equivalently be described as the final stage of a
weakening Z source flaring branch, thereby blurring the line between the two
subclasses. Our findings strongly suggest that the wide variety in behavior
observed in NS-LXMBs with different luminosities can be linked through changes
in a single variable parameter, namely the mass accretion rate, without the
need for additional differences in the neutron star parameters or viewing
angle. We briefly discuss the implications of our findings for the spectral
changes observed in NS LMXBs and suggest that, contrary to what is often
assumed, the position along the color-color tracks of Z sources is not
determined by the instantaneous mass accretion rate.Comment: Submitted to ApJ, comments are welcome. 13 pages, 8 figure
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