6,395 research outputs found
Rural development through local initiatives: observations on Kenya's experiences with Harambee projects in selected rural commnunities
This paper on Harambee in Kenya focuses on two questions: l) Are
locally-initiated Harambee projects an equitable means of resource
distribution, providing benefits across social and economic strata, and
increasing the community's levels of welfare and productivity? 2) In
what ways does Harambee foster local-level initiative, self-reliance and
organizational capability? It draws on data collected in six Locations
in three Districts of Kenya during 1978 and 1979.
Evidence from this study suggests that local development through
Harambee efforts is not characterized by an overall pattern of discrimination
against the poor, and that costs and benefits are distributed among all socioeconomic
groups. Contribution levels are higher among more affluent socioeconomic
groups while benefits are enjoyed across socio-economic strata.
Benefits accruing particularly to higher or lower socio-economic groups
vary according to type of project.
Although heavily dependent on local official leadership, the
Harambee project committee structure does provide some limited organizational
experience as well as an opportunity for the rural population to develop
management skills. However, at present these experiences are enjoyed
primarily, although not exclusively, by the more affluent members of rural
communities
Interpreting Spectral Energy Distributions from Young Stellar Objects. I. A grid of 200,000 YSO model SEDs
We present a grid of radiation transfer models of axisymmetric young stellar
objects (YSOs), covering a wide range of stellar masses (from 0.1Msun to
50Msun) and evolutionary stages (from the early envelope infall stage to the
late disk-only stage). The grid consists of 20,000 YSO models, with spectral
energy distributions (SEDs) and polarization spectra computed at ten viewing
angles for each model, resulting in a total of 200,000 SEDs. [...]. These
models are publicly available on a dedicated WWW server:
http://www.astro.wisc.edu/protostars/ . In this paper we summarize the main
features of our models, as well as the range of parameters explored. [...]. We
examine the dependence of the spectral indices of the model SEDs on envelope
accretion rate and disk mass. In addition, we show variations of spectral
indices with stellar temperature, disk inner radius, and disk flaring power for
a subset of disk-only models. We also examine how changing the wavelength range
of data used to calculate spectral indices affects their values. We show sample
color-color plots of the entire grid as well as simulated clusters at various
distances with typical {\it Spitzer Space Telescope} sensitivities. We find
that young embedded sources generally occupy a large region of color-color
space due to inclination and stellar temperature effects. Disk sources occupy a
smaller region of color-color space, but overlap substantially with the region
occupied by embedded sources, especially in the near- and mid-IR. We identify
regions in color-color space where our models indicate that only sources at a
given evolutionary stage should lie. [...].Comment: 69 pages, 28 figures, Accepted for publication in ApJS. Preprint with
full resolution figures available at http://www.astro.wisc.edu/protostars
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VA Accountability Act of 2015 (H.R. 1994), as Reported to the House
[Excerpt] This report describes the VA Accountability Act of 2015 (H.R. 1994) as reported to the House by the Committee on Veterans Affairs on July 23 2015 and compares it to current law where appropriate. A press account has reported that Chairman Jeff Miller may meet with all committee members to seek views of the minority before floor action. As a result of this meeting, it is possible that the final bill that will go to the House floor may have some provisions that differ from those that the Committee reported.
This report provides a section-by-section description of the act
2-D and 3-D Radiation Transfer Models of High-Mass Star Formation
2-D and 3-D radiation transfer models of forming stars generally produce
bluer 1-10 micron colors than 1-D models of the same evolutionary state and
envelope mass. Therefore, 1-D models of the shortwave radiation will generally
estimate a lower envelope mass and later evolutionary state than
multidimensional models. 1-D models are probably reasonable for very young
sources, or longwave analysis (wavelengths > 100 microns). In our 3-D models of
high-mass stars in clumpy molecular clouds, we find no correlation between the
depth of the 10 micron silicate feature and the longwave (> 100 micron) SED
(which sets the envelope mass), even when the average optical extinction of the
envelope is >100 magnitudes. This is in agreement with the observations of
Faison et al. (1998) of several UltraCompact HII (UCHII) regions, suggesting
that many of these sources are more evolved than embedded protostars.
We have calculated a large grid of 2-D models and find substantial overlap
between different evolutionary states in the mid-IR color-color diagrams. We
have developed a model fitter to work in conjunction with the grid to analyze
large datasets. This grid and fitter will be expanded and tested in 2005 and
released to the public in 2006.Comment: 10 pages, 8 figures, to appear in the proceedings of IAU Symp 227,
Massive Star Birth: A Crossroads of Astrophysics, (Cesaroni R., Churchwell
E., Felli M., Walmsley C. editors
Superluminous supernovae: No threat from Eta Carinae
Recently Supernova 2006gy was noted as the most luminous ever recorded, with
a total radiated energy of ~10^44 Joules. It was proposed that the progenitor
may have been a massive evolved star similar to eta Carinae, which resides in
our own galaxy at a distance of about 2.3 kpc. eta Carinae appears ready to
detonate. Although it is too distant to pose a serious threat as a normal
supernova, and given its rotation axis is unlikely to produce a Gamma-Ray Burst
oriented toward the Earth, eta Carinae is about 30,000 times nearer than
2006gy, and we re-evaluate it as a potential superluminous supernova. We find
that given the large ratio of emission in the optical to the X-ray, atmospheric
effects are negligible. Ionization of the atmosphere and concomitant ozone
depletion are unlikely to be important. Any cosmic ray effects should be spread
out over ~10^4 y, and similarly unlikely to produce any serious perturbation to
the biosphere. We also discuss a new possible effect of supernovae, endocrine
disruption induced by blue light near the peak of the optical spectrum. This is
a possibility for nearby supernovae at distances too large to be considered
"dangerous" for other reasons. However, due to reddening and extinction by the
interstellar medium, eta Carinae is unlikely to trigger such effects to any
significant degree.Comment: 19 pages, 2 figures; Revised version as accepted for publication in
Astrobiolog
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Wnt5a induces ROR1 to recruit cortactin to promote breast-cancer migration and metastasis.
ROR1 is a conserved oncoembryonic surface protein expressed in breast cancer. Here we report that ROR1 associates with cortactin in primary breast-cancer cells or in MCF7 transfected to express ROR1. Wnt5a also induced ROR1-dependent tyrosine phosphorylation of cortactin (Y421), which recruited ARHGEF1 to activate RhoA and promote breast-cancer-cell migration; such effects could be inhibited by cirmtuzumab, a humanized mAb specific for ROR1. Furthermore, treatment of mice bearing breast-cancer xenograft with cirmtuzumab inhibited cortactin phosphorylation in vivo and impaired metastatic development. We established that the proline at 841 of ROR1 was required for it to recruit cortactin and ARHGEF1, activate RhoA, and enhance breast-cancer-cell migration in vitro or development of metastases in vivo. Collectively, these studies demonstrate that the interaction of ROR1 with cortactin plays an important role in breast-cancer-cell migration and metastasis
Rapid Circumstellar Disk Evolution and an Accelerating Star Formation Rate in the Infrared Dark Cloud M17 SWex
We present a catalog of 840 X-ray sources and first results from a 100 ks
Chandra X-ray Observatory imaging study of the filamentary infrared dark cloud
G014.22500.506, which forms the central regions of a larger cloud complex
known as the M17 southwest extension (M17 SWex). In addition to the rich
population of protostars and young stellar objects with dusty circumstellar
disks revealed by Spitzer Space Telescope archival data, we discover a
population of X-ray-emitting, intermediate-mass pre--main-sequence stars (IMPS)
that lack infrared excess emission from circumstellar disks. We model the
infrared spectral energy distributions of this source population to measure its
mass function and place new constraints on the inner dust disk destruction
timescales for 2-8 stars. We also place a lower limit on the star
formation rate (SFR) and find that it is quite high ( yr), equivalent to several Orion Nebula Clusters in
G14.2250.506 alone, and likely accelerating. The cloud complex has not
produced a population of massive, O-type stars commensurate with its SFR. This
absence of very massive () stars suggests that either (1)
M17 SWex is an example of a distributed mode of star formation that will
produce a large OB association dominated by intermediate-mass stars but
relatively few massive clusters, or (2) the massive cores are still in the
process of accreting sufficient mass to form massive clusters hosting O stars.Comment: 29 pages, 9 figures, accepted to Ap
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