176,010 research outputs found
Bridging the Innovation Divide: An Agenda for Disseminating Technology Innovations within the Nonprofit Sector
Examines technology practices -- such as neighborhood information systems, electronic advocacy, Internet-based micro enterprise support, and digital inclusion initiatives -- that strengthen the capacity of nonprofits and community organizations
On the need of the Light Elements Primary Process (LEPP)
Extant chemical evolution models underestimate the Galactic production of Sr,
Y and Zr as well as the Solar System abundances of s-only isotopes with
90<A<130. To solve this problem, an additional (unknown) process has been
invoked, the so-called LEPP (Light Element Primary Process). In this paper we
investigate possible alternative solutions. Basing on Full Network Stellar
evolutionary calculations, we investigate the effects on the Solar System
s-only distribution induced by the inclusion of some commonly ignored physical
processes (e.g. rotation) or by the variation of the treatment of convective
overshoot, mass-loss and the efficiency of nuclear processes. Our main findings
are: 1) at the epoch of the formation of the Solar System, our reference model
produces super-solar abundances for the whole s-only distribution, even in the
range 90<A<130; 2) within errors, the s-only distribution relative to 150Sm is
flat; 3) the s-process contribution of the less massive AGB stars (M<1.5 M_SUN)
as well as of the more massive ones (M>4.0 M_SUN) are negligible; 4) the
inclusion of rotation implies a downward shift of the whole distribution with
an higher efficiency for the heavy s-only isotopes, leading to a flatter s-only
distribution; 5) different prescriptions on convection or mass-loss produce
nearly rigid shifts of the whole distribution. In summary, a variation of the
standard paradigm of AGB nucleosynthesis would allow to reconcile models
predictions with Solar System s-only abundances. Nonetheless, the LEPP cannot
be definitely ruled out, because of the uncertainties still affecting stellar
and Galactic chemical evolution models.Comment: Accepted for publication on Ap
The radio and IR counterparts of the ring nebula around HD211564
We report the detection of the radio and infrared counterparts of the ring
nebula around the WN3(h) star HD211564 (WR152), located to the southwest of the
HII region Sh2132. Using radio continuum data from the Canadian Galactic Plane
Survey, we identified the radio counterparts of the two concentric rings, of
about 9' and 16' in radius, related to the star. After applying a filling
factor f = 0.05-0.12, electron densities and ionized masses are in the range
10-16 cm^-3 and 450-700 Mo, respectively. The analysis of the HI gas emission
distribution allowed the identification of 5900 Mo of neutral atomic gas with
velocities between -52 and -43 km/s probably linked to the nebula. The region
of the nebula is almost free of molecular gas. Only four small clumps were
detected, with a total molecular mass of 790 Mo. About 310 Mo are related to a
small infrared shell-like source linked to the inner ring, which is also
detected in the MSX band A. An IRAS YSO candidate is detected in coincidence
with the shell-like IR source.
We suggest that the optical nebula and its neutral counterparts originated
from the stellar winds from the WR star and its massive progenitor, and are
evolving in the envelope of a slowly expanding shell centered at (l,b) = (102
30, -0 50), of about 31 pc in radius. The bubble's energy conversion efficiency
is in agreement with recent numerical analysis and with observational results.Comment: 11 pages, 7 figures, accepted in MNRA
Molecular line profiles as diagnostics of protostellar collapse: modelling the `blue asymmetry' in inside-out infall
The evolution of star-forming core analogues undergoing inside-out collapse
is studied with a multi-point chemodynamical model which self-consistently
computes the abundance distribution of chemical species in the core. For
several collapse periods the output chemistry of infall tracer species such as
HCO+, CS, and N2H+, is then coupled to an accelerated Lambda-iteration
radiative transfer code, which predicts the emerging molecular line profiles
using two different input gas/dust temperature distributions. We investigate
the sensitivity of the predicted spectral line profiles and line asymmetry
ratios to the core temperature distribution, the time-dependent model
chemistry, as well as to ad hoc abundance distributions. The line asymmetry is
found to be strongly dependent on the adopted chemical abundance distribution.
In general, models with a warm central region show higher values of blue
asymmetry in optically thick HCO+ and CS lines than models with a starless core
temperature profile. We find that in the formal context of Shu-type inside-out
infall, and in the absence of rotation or outflows, the relative blue asymmetry
of certain HCO+ and CS transitions is a function of time and, subject to the
foregoing caveats, can act as a collapse chronometer. The sensitivity of
simulated HCO+ line profiles to linear radial variations, subsonic or
supersonic, of the internal turbulence field is investigated in the separate
case of static cores.Comment: Accepted to MNRAS; 20 pages, 13 fig
Interpreting broad emission-line variations I : Factors influencing the emission-line response
We investigate the sensitivity of the measured broad emission-line
responsivity dlog f_line/dlog f_cont to continuum variations in the context of
straw-man BLR geometries of varying size with fixed BLR boundaries, and for
which the intrinsic emission-line responsivity is known a priori. We find for a
generic emission-line that the measured responsivity, delay and maximum of the
cross-correlation function are correlated for characteristic continuum
variability timescales T_char less than the maximum delay for that line
tau_max(line) for a particular choice of BLR geometry and observer orientation.
The above correlations are manifestations of geometric dilution arising from
reverberation effects within the spatially extended BLR. When present,
geometric dilution reduces the measured responsivity, delay and maximum of the
cross-correlation function. We also find that the measured responsivity and
delay show a strong dependence on light-curve duration, with shorter campaigns
resulting in smaller than expected values, and only a weak dependence on
sampling rate.
The observed strong negative correlation between continuum level and line
responsivity found in previous studies cannot be explained by differences in
the sampling pattern, light-curve duration or in terms of purely geometrical
effects. To explain this and to satisfy the observed positive correlation
between continuum luminosity and BLR size in an individual source, the
responsivity-weighted radius must increase with increasing continuum
luminosity. For a BLR with fixed inner and outer boundaries this requires
radial surface emissivity distributions which deviate significantly from a
simple power-law, and in such a way that the intrinsic emission-line
responsivity increases toward larger BLR radii, in line with photoionisation
calculations.Comment: 21 pages, 17 figures, accepted for publication in MNRAS July 201
Fostering implementation of health services research findings into practice: a consolidated framework for advancing implementation science
Abstract Background Many interventions found to be effective in health services research studies fail to translate into meaningful patient care outcomes across multiple contexts. Health services researchers recognize the need to evaluate not only summative outcomes but also formative outcomes to assess the extent to which implementation is effective in a specific setting, prolongs sustainability, and promotes dissemination into other settings. Many implementation theories have been published to help promote effective implementation. However, they overlap considerably in the constructs included in individual theories, and a comparison of theories reveals that each is missing important constructs included in other theories. In addition, terminology and definitions are not consistent across theories. We describe the Consolidated Framework For Implementation Research (CFIR) that offers an overarching typology to promote implementation theory development and verification about what works where and why across multiple contexts. Methods We used a snowball sampling approach to identify published theories that were evaluated to identify constructs based on strength of conceptual or empirical support for influence on implementation, consistency in definitions, alignment with our own findings, and potential for measurement. We combined constructs across published theories that had different labels but were redundant or overlapping in definition, and we parsed apart constructs that conflated underlying concepts. Results The CFIR is composed of five major domains: intervention characteristics, outer setting, inner setting, characteristics of the individuals involved, and the process of implementation. Eight constructs were identified related to the intervention (e.g., evidence strength and quality), four constructs were identified related to outer setting (e.g., patient needs and resources), 12 constructs were identified related to inner setting (e.g., culture, leadership engagement), five constructs were identified related to individual characteristics, and eight constructs were identified related to process (e.g., plan, evaluate, and reflect). We present explicit definitions for each construct. Conclusion The CFIR provides a pragmatic structure for approaching complex, interacting, multi-level, and transient states of constructs in the real world by embracing, consolidating, and unifying key constructs from published implementation theories. It can be used to guide formative evaluations and build the implementation knowledge base across multiple studies and settings.http://deepblue.lib.umich.edu/bitstream/2027.42/78272/1/1748-5908-4-50.xmlhttp://deepblue.lib.umich.edu/bitstream/2027.42/78272/2/1748-5908-4-50-S1.PDFhttp://deepblue.lib.umich.edu/bitstream/2027.42/78272/3/1748-5908-4-50-S3.PDFhttp://deepblue.lib.umich.edu/bitstream/2027.42/78272/4/1748-5908-4-50-S4.PDFhttp://deepblue.lib.umich.edu/bitstream/2027.42/78272/5/1748-5908-4-50.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/78272/6/1748-5908-4-50-S2.PDFPeer Reviewe
Dusty shells surrounding the carbon variables S Scuti and RT Capricorni
For the Mass-loss of Evolved StarS (MESS) programme, the unprecedented
spatial resolution of the PACS photometer on board the Herschel space
observatory was employed to map the dusty environments of asymptotic giant
branch (AGB) and red supergiant (RSG) stars. Among the morphologically
heterogeneous sample, a small fraction of targets is enclosed by spherically
symmetric detached envelopes. Based on observations in the 70 {\mu}m and 160
{\mu}m wavelength bands, we investigated the surroundings of the two carbon
semiregular variables S Sct and RT Cap, which both show evidence for a history
of highly variable mass-loss. S Sct exhibits a bright, spherically symmetric
detached shell, 138" in diameter and co-spatial with an already known CO
structure. Moreover, weak emission is detected at the outskirts, where the
morphology seems indicative of a mild shaping by interaction of the wind with
the interstellar medium, which is also supported by the stellar space motion.
Two shells are found around RT Cap that were not known so far in either dust
emission or from molecular line observations. The inner shell with a diameter
of 188" shows an almost immaculate spherical symmetry, while the outer ~5'
structure is more irregularly shaped. MoD, a modification of the DUSTY
radiative transfer code, was used to model the detached shells. Dust
temperatures, shell dust masses, and mass-loss rates are derived for both
targets
Diffuse -rays and flux from dark matter annihilation -- a model for consistent results with EGRET and cosmic ray data
In this work we develop a new propagation model for the Galactic cosmic rays
based on the GALPROP code, including contributions from dark matter
annihilation. The model predicts compatible Galactic diffuse ray
spectra with EGRET data in all sky regions. It also gives consistent results of
the diffuse ray longitude and latitude distributions. Further the
results for B/C, Be/Be, proton, electron and antiproton spectra are
also consistent with cosmic ray measurements. In the model we have taken a
universal proton spectrum throughout the Galaxy without introducing large
fluctuation for the proton energy loss is negligible. The dark matter
annihilation signals are `boosted' after taking the contribution from subhalos
into account. Another interesting feature of the model is that it gives better
description of the diffuse rays when taking the source distribution
compatible with supernova remnants data, which is different from previous
studies.Comment: 29 pages, 13 figures; the published versio
Microquasar models for 3EG J1828+0142 and 3EG J1735-1500
Microquasars are promising candidates to emit high-energy gamma-rays.
Moreover, statistical studies show that variable EGRET sources at low galactic
latitudes could be associated with the inner spiral arms. The variable nature
and the location in the Galaxy of the high-mass microquasars, concentrated in
the galactic plane and within 55 degrees from the galactic center, give to
these objects the status of likely counterparts of the variable low-latitude
EGRET sources. We consider in this work the two most variable EGRET sources at
low-latitudes: 3EG J1828+0142 and 3EG J1735-1500, proposing a microquasar model
to explain the EGRET data in consistency with the observations at lower
energies (from radio frequencies to soft gamma-rays) within the EGRET error
box.Comment: (1)Universitat de Barcelona, (2)Instituto Argentino de
Radioastronomia (3) Facultad de Ciencias Astronomicas y Geofisicas
(4)Lawrence Livermore National Laboratory 6 pages, 2 figures. Presented as a
poster at the V Microquasar Workshop, Beijing, June 2004. Accepted for
publication in the Chinese Journal of Astronomy & Astrophysic
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