696 research outputs found
Faxen relations in solids - a generalized approach to particle motion in elasticity and viscoelasticity
A movable inclusion in an elastic material oscillates as a rigid body with
six degrees of freedom. Displacement/rotation and force/moment tensors which
express the motion of the inclusion in terms of the displacement and force at
arbitrary exterior points are introduced. Using reciprocity arguments two
general identities are derived relating these tensors. Applications of the
identities to spherical particles provide several new results, including simple
expressions for the force and moment on the particle due to plane wave
excitation.Comment: 11 pages, 4 figure
Unbound states of 32Cl and the 31S(p,\gamma)32Cl reaction rate
The 31S(p,\gamma)32Cl reaction is expected to provide the dominant break-out
path from the SiP cycle in novae and is important for understanding enrichments
of sulfur observed in some nova ejecta. We studied the 32S(3He,t)32Cl
charge-exchange reaction to determine properties of proton-unbound levels in
32Cl that have previously contributed significant uncertainties to the
31S(p,\gamma)32Cl reaction rate. Measured triton magnetic rigidities were used
to determine excitation energies in 32Cl. Proton-branching ratios were obtained
by detecting decay protons from unbound 32Cl states in coincidence with
tritons. An improved 31S(p,\gamma)32Cl reaction rate was calculated including
robust statistical and systematic uncertainties
Guiding neutral atoms around curves with lithographically patterned current-carrying wires
Laser-cooled neutral atoms from a low-velocity atomic source are guided via a
magnetic field generated between two parallel wires on a glass substrate. The
atoms bend around three curves, each with a 15-cm radius of curvature, while
traveling along a 10-cm-long track. A maximum flux of 2*10^6 atoms/sec is
achieved with a current density of 3*10^4 A/cm^2 in the
100x100-micrometer-cross-section wires. The kinetic energy of the guided atoms
in one transverse dimension is measured to be 42 microKelvin.Comment: 9 page
Time to go global: a consultation on global health competencies for postgraduate doctors
BACKGROUND: Globalisation is having profound impacts on health and healthcare. We solicited the views of a wide range of stakeholders in order to develop core global health competencies for postgraduate doctors. METHODS: Published literature and existing curricula informed writing of seven global health competencies for consultation. A modified policy Delphi involved an online survey and face-to-face and telephone interviews over three rounds. RESULTS: Over 250 stakeholders participated, including doctors, other health professionals, policymakers and members of the public from all continents of the world. Participants indicated that global health competence is essential for postgraduate doctors and other health professionals. Concerns were expressed about overburdening curricula and identifying what is 'essential' for whom. Conflicting perspectives emerged about the importance and relevance of different global health topics. Five core competencies were developed: (1) diversity, human rights and ethics; (2) environmental, social and economic determinants of health; (3) global epidemiology; (4) global health governance; and (5) health systems and health professionals. CONCLUSIONS: Global health can bring important perspectives to postgraduate curricula, enhancing the ability of doctors to provide quality care. These global health competencies require tailoring to meet different trainees' needs and facilitate their incorporation into curricula. Healthcare and global health are ever-changing; therefore, the competencies will need to be regularly reviewed and updated
RNAi suppression of xylan synthase genes in wheat starchy endosperm
The xylan backbone of arabinoxylan (AX), the major cell wall polysaccharide in the wheat starchy endosperm, is synthesised by xylan synthase which is a complex of three subunits encoded by the GT43_1, GT43_2 and GT47_2 genes. RNAi knock-down of either GT43_1 or all three genes (triple lines) resulted in decreased AX measured by digestion with endoxylanase (to 33 and 34.9% of the controls) and by monosaccharide analysis (to 45.9% and 47.4% of the controls) with greater effects on the amount of water-extractable AX (to 20.6 and 19.9% of the controls). Both sets of RNAi lines also had greater decreases in the amounts of substituted oligosaccharides released by digestion of AX with endoxylanase than in fragments derived only from the xylan backbone. Although the GT43_1 and triple lines had similar effects on AX they did differ in their contents of soluble sugars (increased in triple only) and on grain size (decreased in triple only). Both sets of transgenic lines had decreased grain hardness, indicating effects on cell wall mechanics. These results, and previously published studies of RNAi suppression of GT43_2 and GT47_2 and of a triple mutant of GT43_2, are consistent with the model of xylan synthase comprising three subunits one of which (GT47_2) is responsible for catalysis with the other two subunits being required for correct functioning but indicate that separate xylan synthase complexes may be responsible for the synthesis of populations of AX which differ in their structure and solubility
A microsatellite repeat in PCA3 long non-coding RNA is associated with prostate cancer risk and aggressiveness.
Short tandem repeats (STRs) are repetitive sequences of a polymorphic stretch of two to six nucleotides. We hypothesized that STRs are associated with prostate cancer development and/or progression. We undertook RNA sequencing analysis of prostate tumors and adjacent non-malignant cells to identify polymorphic STRs that are readily expressed in these cells. Most of the expressed STRs in the clinical samples mapped to intronic and intergenic DNA. Our analysis indicated that three of these STRs (TAAA-ACTG2, TTTTG-TRIB1, and TG-PCA3) are polymorphic and differentially expressed in prostate tumors compared to adjacent non-malignant cells. TG-PCA3 STR expression was repressed by the anti-androgen drug enzalutamide in prostate cancer cells. Genetic analysis of prostate cancer patients and healthy controls (N > 2,000) showed a significant association of the most common 11 repeat allele of TG-PCA3 STR with prostate cancer risk (OR = 1.49; 95% CI 1.11-1.99; P = 0.008). A significant association was also observed with aggressive disease (OR = 2.00; 95% CI 1.06-3.76; P = 0.031) and high mortality rates (HR = 3.0; 95% CI 1.03-8.77; P = 0.045). We propose that TG-PCA3 STR has both diagnostic and prognostic potential for prostate cancer. We provided a proof of concept to be applied to other RNA sequencing datasets to identify disease-associated STRs for future clinical exploratory studies
A Global Perspective on Trends in Nature-Based Tourism
Falling attendance at United States and Japanese national parks has led to claims of a pervasive shift away from nature-based recreation. A global analysis, however, now suggests that while visit rates are declining slightly in some richer countries, elsewhere nature tourism is booming
Elemental energy spectra of cosmic rays measured by CREAM-II
We present new measurements of the energy spectra of cosmic-ray (CR) nuclei
from the second flight of the balloon-borne experiment CREAM (Cosmic Ray
Energetics And Mass). The instrument (CREAM-II) was comprised of detectors
based on different techniques (Cherenkov light, specific ionization in
scintillators and silicon sensors) to provide a redundant charge identification
and a thin ionization calorimeter capable of measuring the energy of cosmic
rays up to several hundreds of TeV. The data analysis is described and the
individual energy spectra of C, O, Ne, Mg, Si and Fe are reported up to ~ 10^14
eV. The spectral shape looks nearly the same for all the primary elements and
can be expressed as a power law in energy E^{-2.66+/-0.04}. The nitrogen
absolute intensity in the energy range 100-800 GeV/n is also measured.Comment: 4 pages, 3 figures, presented at ICRC 2009, Lodz, Polan
Measurements of cosmic-ray energy spectra with the 2nd CREAM flight
During its second Antarctic flight, the CREAM (Cosmic Ray Energetics And
Mass) balloon experiment collected data for 28 days, measuring the charge and
the energy of cosmic rays (CR) with a redundant system of particle
identification and an imaging thin ionization calorimeter. Preliminary direct
measurements of the absolute intensities of individual CR nuclei are reported
in the elemental range from carbon to iron at very high energy.Comment: 4 pages, 3 figures, presented at XV International Symposium on Very
High Energy Cosmic Ray Interactions (ISVHECRI 2008
Agent-based model of angiogenesis simulates capillary sprout initiation in multicellular networks
We developed an agent-based model of endothelial sprout initiations based on time-lapse confocal imaging in vitro that outperforms Monte Carlo simulations, suggesting that sprout location and frequency are not purely stochastic behaviors
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