5,259 research outputs found
Universal Properties of Linear Magnetoresistance in Strongly Disordered Semiconductors
Linear magnetoresistance occurs in semiconductors as a consequence of strong
electrical disorder and is characterized by nonsaturating magnetoresistance
that is proportional to the applied magnetic field. By investigating a
disordered MnAs-GaAs composite material, it is found that the magnitude of the
linear magnetoresistance (LMR) is numerically equal to the carrier mobility
over a wide range and is independent of carrier density. This behavior is
complementary to the Hall effect that is independent of the mobility and
dependent on the carrier density. Moreover, the LMR appears to be insensitive
to the details of the disorder and points to a universal explanation of
classical LMR that can be applied to other material systems.Comment: Accepted by Phys. Rev. B (2010
Community-onset Staphylococcus aureus infections presenting to general practices in South-eastern Australia
Community-acquired Staphylococcus aureus infections are a public health concern, yet little is known about infections that do not present to hospital. We identified community-onset S. aureus infections via specimens submitted to a community-based pathology service. Referring doctors confirmed eligibility and described infection site, severity and treatment. Isolates were characterized on antibiotic resistance, PFGE, MLST/SCCmec, and Panton–Valentine leukocidin (PVL), representing 106 community-onset infections; 34 non-multiresistant methicillin-resistant S. aureus (nmMRSA) (resistant to <3 non-β-lactam antibiotics), 15 multiply antibiotic-resistant MRSA (mMRSA) and 57 methicillin-sensitive S. aureus (MSSA). Most (93%) were skin and soft tissue infections. PVL genes were carried by 42% of nmMRSA isolates [95% confidence interval (CI) 26–61] and 15% of MSSA (95% CI 8–28). PVL was associated with infections of the trunk, head or neck (56•4% vs. 24•3%, P = 0•005) in younger patients (23 vs. 52 years, P < 0•001), and with boils or abscesses (OR 8•67, 95% CI 2•9–26•2), suggesting underlying differences in exposure and/or pathogenesis
Metastatic Squamous Cell Carcinoma in a Northern Brown Bandicoot (<i>Isoodon macrourus</i>)
Aside from a handful of notable exceptions, neoplasia is not reported as a major cause of mortality in wild animal populations and often goes undetected. For northern brown bandicoots specifically, there are few reported tumors in the literature and on file in the Australian Registry of Wildlife Health. This report describes a case of squamous cell carcinoma in a northern brown bandicoot (Isoodon macrourus), with metastases to the draining lymph nodes and lung. This neoplasm consisted predominantly of well-differentiated squamous cells and multifocal keratin pearls, with areas possibly consistent with epithelial to mesenchymal transition, as identified by positive immunohistochemical staining by both pancytokeratin (AE1/AE3) and vimentin. Additional investigations were negative for bandicoot papillomatosis carcinomatosis viruses
Resource Loss and Depressive Symptoms Following Hurricane Katrina: A Principal Component Regression Study
To understand the relationship between the structure of resource loss and depression after disaster exposure, the components of resource loss and the impact of these resource loss components on depression was examined among college students (N=654) at two universities who were affected by Hurricane Katrina. The component of resource loss was analyzed by principal component analysis first. Gender, social relationship loss, and financial loss were then examined with the regression model on depression. Financial loss was a significant predictor of depression. Social relationship loss did not predict depression significantly. In predicting depression, resource loss was more important for females than for males
Observations of the Binary Microlens Event MACHO-98-SMC-1 by the Microlensing Planet Search Collaboration
We present the observations of the binary lensing event MACHO-98-SMC-1
conducted at the Mt.~Stromlo 74" telescope by the Microlensing Planet Search
(MPS) collaboration. The MPS data constrain the first caustic crossing to have
occurred after 1998 June 5.55 UT and thus directly rule out one of the two fits
presented by the PLANET collaboration (model II). This substantially reduces
the uncertainty in the the relative proper motion estimations of the lens
object.
We perform joint binary microlensing fits of the MPS data together with the
publicly available data from the EROS, MACHO/GMAN and OGLE collaborations. We
also study the binary lens fit parameters previously published by the PLANET
and MACHO/GMAN collaborations by using them as initial values for
minimization. Fits based on the PLANET model I appear to be in conflict with
the GMAN-CTIO data. From our best fit, we find that the lens system has a
proper motion of \mu = 1.3\pm 0.2 \kmsk with respect to the source, which
implies that the lens system is most likely to be located in the Small
Magellanic Cloud strengthening the conclusion of previous reports.Comment: 20 pages, 4 color figure
ROMA: a map-making algorithm for polarised CMB data sets
We present ROMA, a parallel code to produce joint optimal temperature and
polarisation maps out of multidetector CMB observations. ROMA is a fast,
accurate and robust implementation of the iterative generalised least squares
approach to map-making. We benchmark ROMA on realistic simulated data from the
last, polarisation sensitive, flight of BOOMERanG.Comment: Accepted for publication in Astronomy & Astrophysics. Version with
higher quality figures available at http://www.fisica.uniroma2.it/~cosmo/ROM
Planetary and Other Short Binary Microlensing Events from the MOA Short Event Analysis
We present the analysis of four candidate short duration binary microlensing
events from the 2006-2007 MOA Project short event analysis. These events were
discovered as a byproduct of an analysis designed to find short timescale
single lens events that may be due to free-floating planets. Three of these
events are determined to be microlensing events, while the fourth is most
likely caused by stellar variability. For each of the three microlensing
events, the signal is almost entirely due to a brief caustic feature with
little or no lensing attributable mainly to the lens primary. One of these
events, MOA-bin-1, is due to a planet, and it is the first example of a
planetary event in which stellar host is only detected through binary
microlensing effects. The mass ratio and separation are q = 4.9 +- 1.4 x
10^{-3} and s = 2.10 +- 0.05, respectively. A Bayesian analysis based on a
standard Galactic model indicates that the planet, MOA-bin-1Lb, has a mass of
m_p = 3.7 +- 2.1 M_{Jup}, and orbits a star of M_* = 0.75{+0.33 -0.41} M_solar
at a semi-major axis of a = 8.3 {+4.5 -2.7} AU. This is one of the most massive
and widest separation planets found by microlensing. The scarcity of such wide
separation planets also has implications for interpretation of the isolated
planetary mass objects found by this analysis. If we assume that we have been
able to detect wide separation planets with a efficiency at least as high as
that for isolated planets, then we can set limits on the distribution on
planets in wide orbits. In particular, if the entire isolated planet sample
found by Sumi et al. (2011) consists of planets bound in wide orbits around
stars, we find that it is likely that the median orbital semi-major axis is >
30 AU.Comment: 47 pages with 14 figure
MOA-2016-BLG-227Lb: A Massive Planet Characterized by Combining Light-curve Analysis and Keck AO Imaging
We report the discovery of a microlensing planet—MOA-2016-BLG-227Lb—with a large planet/host mass ratio of q ≃ 9 × 10−3. This event was located near the K2 Campaign 9 field that was observed by a large number of telescopes. As a result, the event was in the microlensing survey area of a number of these telescopes, and this enabled good coverage of the planetary light-curve signal. High angular resolution adaptive optics images from the Keck telescope reveal excess flux at the position of the source above the flux of the source star, as indicated by the light-curve model. This excess flux could be due to the lens star, but it could also be due to a companion to the source or lens star, or even an unrelated star. We consider all these possibilities in a Bayesian analysis in the context of a standard Galactic model. Our analysis indicates that it is unlikely that a large fraction of the excess flux comes from the lens, unless solar-type stars are much more likely to host planets of this mass ratio than lower mass stars. We recommend that a method similar to the one developed in this paper be used for other events with high angular resolution follow-up observations when the follow-up observations are insufficient to measure the lens–source relative proper motion
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