1,231 research outputs found
Secondary Structures in Long Compact Polymers
Compact polymers are self-avoiding random walks which visit every site on a
lattice. This polymer model is used widely for studying statistical problems
inspired by protein folding. One difficulty with using compact polymers to
perform numerical calculations is generating a sufficiently large number of
randomly sampled configurations. We present a Monte-Carlo algorithm which
uniformly samples compact polymer configurations in an efficient manner
allowing investigations of chains much longer than previously studied. Chain
configurations generated by the algorithm are used to compute statistics of
secondary structures in compact polymers. We determine the fraction of monomers
participating in secondary structures, and show that it is self averaging in
the long chain limit and strictly less than one. Comparison with results for
lattice models of open polymer chains shows that compact chains are
significantly more likely to form secondary structure.Comment: 14 pages, 14 figure
The impact of the demographic transition on dengue in Thailand: Insights from a statistical analysis and mathematical modeling
Background: An increase in the average age of dengue hemorrhagic fever (DHF) cases has been reported in Thailand. The cause of this increase is not known. Possible explanations include a reduction in transmission due to declining mosquito populations, declining contact between human and mosquito, and changes in reporting. We propose that a demographic shift toward lower birth and death rates has reduced dengue transmission and lengthened the interval between large epidemics. Methods and Findings: Using data from each of the 72 provinces of Thailand, we looked for associations between force of infection (a measure of hazard, defined as the rate per capita at which susceptible individuals become infected) and demographic and climactic variables. We estimated the force of infection from the age distribution of cases from 1985 to 2005. We find that the force of infection has declined by 2% each year since a peak in the late 1970s and early 1980s. Contrary to recent findings suggesting that the incidence of DHF has increased in Thailand, we find a small but statistically significant decline in DHF incidence since 1985 in a majority of provinces. The strongest predictor of the change in force of infection and the mean force of infection is the median age of the population. Using mathematical simulations of dengue transmission we show that a reduced birth rate and a shift in the population's age structure can explain the shift in the age distribution of cases, reduction of the force of infection, and increase in the periodicity of multiannual oscillations of DHF incidence in the absence of other changes. Conclusions: Lower birth and death rates decrease the flow of susceptible individuals into the population and increase the longevity of immune individuals. The increase in the proportion of the population that is immune increases the likelihood that an infectious mosquito will feed on an immune individual, reducing the force of infection. Though the force of infection has decreased by half, we find that the critical vaccination fraction has not changed significantly, declining from an average of 85% to 80%. Clinical guidelines should consider the impact of continued increases in the age of dengue cases in Thailand. Countries in the region lagging behind Thailand in the demographic transition may experience the same increase as their population ages. The impact of demographic changes on the force of infection has been hypothesized for other diseases, but, to our knowledge, this is the first observation of this phenomenon
Publishing and sharing multi-dimensional image data with OMERO
Imaging data are used in the life and biomedical sciences to measure the molecular and structural composition and dynamics of cells, tissues, and organisms. Datasets range in size from megabytes to terabytes and usually contain a combination of binary pixel data and metadata that describe the acquisition process and any derived results. The OMERO image data management platform allows users to securely share image datasets according to specific permissions levels: data can be held privately, shared with a set of colleagues, or made available via a public URL. Users control access by assigning data to specific Groups with defined membership and access rights. OMERO’s Permission system supports simple data sharing in a lab, collaborative data analysis, and even teaching environments. OMERO software is open source and released by the OME Consortium at www.openmicroscopy.org
The Unusual Infrared Object HDF-N J123656.3+621322
We describe an object in the Hubble Deep Field North with very unusual
near-infrared properties. It is readily visible in Hubble Space Telescope
NICMOS images at 1.6um and from the ground at 2.2um, but is undetected (with
signal-to-noise <~ 2) in very deep WFPC2 and NICMOS data from 0.3 to 1.1um. The
f_nu flux density drops by a factor >~ 8.3 (97.7% confidence) from 1.6 to
1.1um. The object is compact but may be slightly resolved in the NICMOS 1.6um
image. In a low-resolution, near-infrared spectrogram, we find a possible
emission line at 1.643um, but a reobservation at higher spectral resolution
failed to confirm the line, leaving its reality in doubt. We consider various
hypotheses for the nature of this object. Its colors are unlike those of known
galactic stars, except perhaps the most extreme carbon stars or Mira variables
with thick circumstellar dust shells. It does not appear to be possible to
explain its spectral energy distribution as that of a normal galaxy at any
redshift without additional opacity from either dust or intergalactic neutral
hydrogen. The colors can be matched by those of a dusty galaxy at z >~ 2, by a
maximally old elliptical galaxy at z >~ 3 (perhaps with some additional
reddening), or by an object at z >~ 10 whose optical and 1.1um light have been
suppressed by the intergalactic medium. Under the latter hypothesis, if the
luminosity results from stars and not an AGN, the object would resemble a
classical, unobscured protogalaxy, with a star formation rate >~ 100 M_sun/yr.
Such UV-bright objects are evidently rare at 2 < z < 12.5, however, with a
space density several hundred times lower than that of present-day L* galaxies.Comment: Accepted for publication in the Astrophysical Journal. 27 pages,
LaTeX, with 7 figures (8 files); citations & references updated + minor
format change
Sheep Updates 2003 - Wool
This session covers six papers from different authors:1.‘Pastures from space’ - an opportunity to increase the profitability of sheep production Richard Coole Farmer Kojonup W.A. Stephen Gherardi Chris Oldham Department of Agriculture Western Australia 2. K. Curtis Department of Agriculture WA J. Stanton Department of Agriculture WA and Curtin University 3. Is selection of ewe hogget replacement on measurement profitable? Johan Greeff Department of Agriculture of Western Australia 4. Optimising the nutrition/grazing management of ewe flocks Chris Oldham Mike Hyder Beth Paganoni Department of Agriculture of Western Australia Andrew Thompson Department of Primary Industries, Hamilton, Victoria Tom Plaisted Kazue Tanaka Department of Agriculture of Western Australia Mark Ferguson Darren Gordon Department of Primary Industries, Hamilton, Victoria 5. How do we produce wool for next-to-skin wear? Andrew Peterson Department of Agriculture Western Australia 6. Measuring fibre contamination post farm gate Peter Sommerville Corporate Development Manager AWTA Lt
The Grizzly, February 11, 1983
Bookstore Explains Pricing Policy • Scottish Scholarships Offered to Sophomores • Weekend Alcohol Policy: Campus is Dry • Ursinus Gets Bucks From Sears Roebuck • President\u27s Corner • Visser Fills Exhibits in Corson • Letters to the Editor: Professor Laments Social Conditions at UC; I.F.C. President Irate; President\u27s Response; Bitter About Policy • Varying Viewpoints • Stravinsky to End Winterfest • U.C. Flu Flattens Students • Reaganomics Forum • Key Shooting Aids Lady Hoopsters\u27 Record • Basketball Laments Second Half Loss • Swimmers Glide to Third Straight Victory • Grapplers Deemed Tough • Basketball: End of an Era?? • Swimmers Stroke for Two Wins • Gymnasts Win by 0.75https://digitalcommons.ursinus.edu/grizzlynews/1093/thumbnail.jp
Influenza D Virus Infection in Feral Swine Populations, United States
Influenza D virus (IDV) has been identified in domestic cattle, swine, camelid, and small ruminant populations across North America, Europe, Asia, South America, and Africa. Our study investigated seroprevalence and transmissibility of IDV in feral swine. During 2012–2013, we evaluated feral swine populations in 4 US states; of 256 swine tested, 57 (19.1%) were IDV seropositive. Among 96 archived influenza A virus–seropositive feral swine samples collected from 16 US states during 2010–2013, 41 (42.7%) were IDV seropositive. Infection studies demonstrated that IDV-inoculated feral swine shed virus 3–5 days postinoculation and seroconverted at 21 days postinoculation; 50% of in-contact naive feral swine shed virus, seroconverted, or both. Immunohistochemical staining showed viral antigen within epithelial cells of the respiratory tract, including trachea, soft palate, and lungs. Our findings suggest that feral swine might serve an important role in the ecology of IDV
Evaluating the potential for the environmentally sustainable control of foot and mouth disease in Sub-Saharan Africa
Strategies to control transboundary diseases have in the past generated unintended negative consequences for both the environment and local human populations. Integrating perspectives from across disciplines, including livestock, veterinary and conservation sectors, is necessary for identifying disease control strategies that optimise environmental goods and services at the wildlife-livestock interface. Prompted by the recent development of a global strategy for the control and elimination of foot-and-mouth disease (FMD), this paper seeks insight into the consequences of, and rational options for potential FMD control measures in relation to environmental, conservation and human poverty considerations in Africa. We suggest a more environmentally nuanced process of FMD control that safe-guards the integrity of wild populations and the ecosystem dynamics on which human livelihoods depend while simultaneously improving socio-economic conditions of rural people. In particular, we outline five major issues that need to be considered: 1) improved understanding of the different FMD viral strains and how they circulate between domestic and wildlife populations; 2) an appreciation for the economic value of wildlife for many African countries whose presence might preclude the country from ever achieving an FMD-free status; 3) exploring ways in which livestock production can be improved without compromising wildlife such as implementing commodity-based trading schemes; 4) introducing a participatory approach involving local farmers and the national veterinary services in the control of FMD; and 5) finally the possibility that transfrontier conservation might offer new hope of integrating decision-making at the wildlife-livestock interface
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