4,451 research outputs found
Supplemental Nutrition Assistance Program Education Evaluation and Database System
Reporting requirements for capturing data on the delivery of Supplemental Nutrition Assistance Program Education (SNAP-Ed) have evolved. University of Minnesota (U of M) Extension developed the SNAP Education Evaluation and Database System (SEEDS) to capture unduplicated participant information for SNAP-Ed programming conducted by U of M Extension across the state of Minnesota. The data collected in SEEDS have utility related to both managing programs and measuring the success of programs at local, regional, and state levels. Extension professionals in other states may benefit from developing a similar centralized database for collecting SNAP-Ed data
Determining the structure of Ru(0001) from low-energy electron diffraction of a single terrace
While a perfect hcp (0001) surface has three-fold symmetry, the diffraction
patterns commonly obtained are six-fold symmetric. This apparent change in
symmetry occurs because on a stepped surface, the atomic layers on adjacent
terraces are rotated by 180 degrees. Here we use a Low-Energy Electron
Microscope to acquire the three-fold diffraction pattern from a single hcp Ru
terrace and measure the intensity-vs-energy curves for several diffracted
beams. By means of multiple scattering calculations fitted to the experimental
data with a Pendry R-factor of 0.077, we find that the surface is contracted by
3.5(+-0.9) at 456 K.Comment: 10 pages, 4 figures. Corrected some typos, added more details.
Accepted for publication in Surface Science (Letters
Evolution of avalanche conducting states in electrorheological liquids
Charge transport in electrorheological fluids is studied experimentally under
strongly nonequlibrium conditions. By injecting an electrical current into a
suspension of conducting nanoparticles we are able to initiate a process of
self-organization which leads, in certain cases, to formation of a stable
pattern which consists of continuous conducting chains of particles. The
evolution of the dissipative state in such system is a complex process. It
starts as an avalanche process characterized by nucleation, growth, and thermal
destruction of such dissipative elements as continuous conducting chains of
particles as well as electroconvective vortices. A power-law distribution of
avalanche sizes and durations, observed at this stage of the evolution,
indicates that the system is in a self-organized critical state. A sharp
transition into an avalanche-free state with a stable pattern of conducting
chains is observed when the power dissipated in the fluid reaches its maximum.
We propose a simple evolution model which obeys the maximum power condition and
also shows a power-law distribution of the avalanche sizes.Comment: 15 pages, 6 figure
How non-linear scaling relations unify dwarf and giant elliptical galaxies
Dwarf elliptical galaxies are frequently excluded from bright galaxy samples
because they do not follow the same linear relations in diagrams involving
effective half light radii R_e or mean effective surface brightnesses _e.
However, using two linear relations which unite dwarf and bright elliptical
galaxies we explain how these lead to curved relations when one introduces
either the half light radius or the associated surface brightness. In
particular, the curved _e - R_e relation is derived here. This and other
previously misunderstood curved relations, once heralded as evidence for a
discontinuity between faint and bright elliptical galaxies at M_B ~ -18 mag,
actually support the unification of such galaxies as a single population whose
structure (i.e. stellar concentration) varies continuously with stellar
luminosity and mass.Comment: 4 pages including 2 figures, to appear in "A Universe of dwarf
galaxies", Conf. Proc. (Lyon, June 14-18, 2010
A Dereplication and Bioguided Discovery Approach to Reveal New Compounds from a Marine-Derived Fungus Stilbella fimetaria
A marine-derived Stilbella fimetaria fungal strain was screened for new bioactive compounds based on two different approaches: (i) bio-guided approach using cytotoxicity and antimicrobial bioassays; and (ii) dereplication based approach using liquid chromatography with both diode array detection and high resolution mass spectrometry. This led to the discovery of several bioactive compound families with different biosynthetic origins, including pimarane-type diterpenoids and hybrid polyketide-non ribosomal peptide derived compounds. Prefractionation before bioassay screening proved to be a great aid in the dereplication process, since separate fractions displaying different bioactivities allowed a quick tentative identification of known antimicrobial compounds and of potential new analogues. A new pimarane-type diterpene, myrocin F, was discovered in trace amounts and displayed cytotoxicity towards various cancer cell lines. Further media optimization led to increased production followed by the purification and bioactivity screening of several new and known pimarane-type diterpenoids. A known broad-spectrum antifungal compound, ilicicolin H, was purified along with two new analogues, hydroxyl-ilicicolin H and ilicicolin I, and their antifungal activity was evaluated
Blue space as caring space – water and the cultivation of care in social and environmental practice
This paper studies three sites or ‘landscapes of care’ in Leeds, Bristol and London where water and associated built and natural environments are used to co-construct and facilitate forms of social and environmental care. Our research narrates the ways in which blue spaces are cultivated for the production of particular forms of caring bodies and sensibilities. Interpreting care as both a doing (caring for) and emotion (caring about), we draw attention to the diverse practices and distributed nature of care in these environments. Our paper has three main insights. First, we draw attention to the role of water as both a material and site of care. Second, we identify a range of more-than-human benefits associated with blue spaces and how these emerge via collaborative, non-linear and reciprocal forms of care. Third, we argue that by understanding how care works in everyday social practice, new forms of ecological care and pro-environmental ways of living with the world can emerge
Galaxy Harassment and the Evolution of Clusters of Galaxies
Disturbed spiral galaxies with high rates of star formation pervaded clusters
of galaxies just a few billion years ago, but nearby clusters exclude spirals
in favor of ellipticals. ``Galaxy harassment" (frequent high speed galaxy
encounters) drives the morphological transformation of galaxies in clusters,
provides fuel for quasars in subluminous hosts and leaves detectable debris
arcs. Simulated images of harassed galaxies are strikingly similar to the
distorted spirals in clusters at observed by the Hubble Space
Telescope.Comment: Submitted to Nature. Latex file, 7 pages, 10 photographs in gif and
jpeg format included. 10 compressed postscript figures and text available
using anonymous ftp from ftp://ftp-hpcc.astro.washington.edu/pub/hpcc/moore/
(mget *) Also available at http://www-hpcc.astro.washington.edu/papers
Nature vs. nurture in the low-density environment: structure and evolution of early-type dwarf galaxies in poor groups
We present the stellar population properties of 13 dwarf galaxies residing in
poor groups (low-density environment, LDE) observed with VIMOS@VLT. Ages,
metallicities, and [alpha/Fe] ratios were derived from the Lick indices Hbeta,
Mgb, Fe5270 and Fe5335 through comparison with our simple stellar population
(SSP) models accounting for variable [alpha/Fe] ratios. For a fiducial
subsample of 10 early-type dwarfs we derive median values and scatters around
the medians of 5.7 \pm 4.4 Gyr, -0.26 \pm 0.28, and -0.04 \pm 0.33 for age, log
Z/Zsun, and [alpha/Fe], respectively. For a selection of bright early-type
galaxies (ETGs) from the Annibali et al.2007 sample residing in comparable
environment we derive median values of 9.8 \pm 4.1 Gyr, 0.06 \pm 0.16, and 0.18
\pm 0.13 for the same stellar population parameters. It follows that dwarfs are
on average younger, less metal rich, and less enhanced in the alpha-elements
than giants, in agreement with the extrapolation to the low mass regime of the
scaling relations derived for giant ETGs. From the total (dwarf + giant) sample
we derive that age \propto sigma^{0.39 \pm 0.22}, Z \propto sigma^{0.80 \pm
0.16}, and alpha/Fe \propto sigma^{0.42 \pm 0.22}. We also find correlations
with morphology, in the sense that the metallicity and the [alpha/Fe] ratio
increase with the Sersic index n or with the bulge-to-total light fraction B/T.
The presence of a strong morphology-[alpha/Fe] relation appears to be in
contradiction to the possible evolution along the Hubble sequence from low B/T
(low n) to high B/T (high n) galaxies. We also investigate the role played by
environment comparing the properties of our LDE dwarfs with those of Coma red
passive dwarfs from the literature. We find possible evidence that LDE dwarfs
experienced more prolonged star formations than Coma dwarfs, however larger
data samples are needed to draw more firm conclusions.Comment: Accepted for publication on A&
Do cancer cells undergo phenotypic switching? The case for imperfect cancer stem cell markers
The identification of cancer stem cells in vivo and in vitro relies on specific surface markers that should allow to sort cancer cells in phenotypically distinct subpopulations. Experiments report that sorted cancer cell populations after some time tend to express again all the original markers, leading to the hypothesis of phenotypic switching, according to which cancer cells can transform stochastically into cancer stem cells. Here we explore an alternative explanation based on the hypothesis that markers are not perfect and are thus unable to identify all cancer stem cells. Our analysis is based on a mathematical model for cancer cell proliferation that takes into account phenotypic switching, imperfect markers and error in the sorting process. Our conclusion is that the observation of reversible expression of surface markers after sorting does not provide sufficient evidence in support of phenotypic switching
A Novel Model of Mixed Vascular Dementia Incorporating Hypertension in a Rat Model of Alzheimer's Disease.
Alzheimer's disease (AD) and mixed dementia (MxD) comprise the majority of dementia cases in the growing global aging population. MxD describes the coexistence of AD pathology with vascular pathology, including cerebral small vessel disease (SVD). Cardiovascular disease increases risk for AD and MxD, but mechanistic synergisms between the coexisting pathologies affecting dementia risk, progression and the ultimate clinical manifestations remain elusive. To explore the additive or synergistic interactions between AD and chronic hypertension, we developed a rat model of MxD, produced by breeding APPswe/PS1ΔE9 transgenes into the stroke-prone spontaneously hypertensive rat (SHRSP) background, resulting in the SHRSP/FAD model and three control groups (FAD, SHRSP and non-hypertensive WKY rats, n = 8-11, both sexes, 16-18 months of age). After behavioral testing, rats were euthanized, and tissue assessed for vascular, neuroinflammatory and AD pathology. Hypertension was preserved in the SHRSP/FAD cross. Results showed that SHRSP increased FAD-dependent neuroinflammation (microglia and astrocytes) and tau pathology, but plaque pathology changes were subtle, including fewer plaques with compact cores and slightly reduced plaque burden. Evidence for vascular pathology included a change in the distribution of astrocytic end-foot protein aquaporin-4, normally distributed in microvessels, but in SHRSP/FAD rats largely dissociated from vessels, appearing disorganized or redistributed into neuropil. Other evidence of SVD-like pathology included increased collagen IV staining in cerebral vessels and PECAM1 levels. We identified a plasma biomarker in SHRSP/FAD rats that was the only group to show increased Aqp-4 in plasma exosomes. Evidence of neuron damage in SHRSP/FAD rats included increased caspase-cleaved actin, loss of myelin and reduced calbindin staining in neurons. Further, there were mitochondrial deficits specific to SHRSP/FAD, notably the loss of complex II, accompanying FAD-dependent loss of mitochondrial complex I. Cognitive deficits exhibited by FAD rats were not exacerbated by the introduction of the SHRSP phenotype, nor was the hyperactivity phenotype associated with SHRSP altered by the FAD transgene. This novel rat model of MxD, encompassing an amyloidogenic transgene with a hypertensive phenotype, exhibits several features associated with human vascular or "mixed" dementia and may be a useful tool in delineating the pathophysiology of MxD and development of therapeutics
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