1,537 research outputs found

    Nonlinear Interactions Between Gravitational Radiation and Modified Alfven Modes in Astrophysical Dusty Plasmas

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    We present an investigation of nonlinear interactions between Gravitational Radiation and modified Alfv\'{e}n modes in astrophysical dusty plasmas. Assuming that stationary charged dust grains form neutralizing background in an electron-ion-dust plasma, we obtain the three wave coupling coefficients, and calculate the growth rates for parametrically coupled gravitational radiation and modified Alfv\'{e}n-Rao modes. The threshold value of the gravitational wave amplitude associated with convective stabilization is particularly small if the gravitational frequency is close to twice the modified Alfv\'en wave-frequency. The implication of our results to astrophysical dusty plasmas is discussed.Comment: A few typos corrected. Published in Phys. Rev.

    Perceived Differences in the Management of Mental Health Patients in Remote and Rural Australia and Strategies for Improvement: Findings from a National Qualitative Study of Emergency Clinicians

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    Introduction. We aimed to describe perceptions of Australian emergency clinicians of differences in management of mental health patients in rural and remote Australia compared with metropolitan hospitals, and what could be improved. Methods. Descriptive exploratory study using semi-structured telephone interviews of doctors and nurses in Australian emergency departments (EDs), stratified to represent states and territories and rural or metropolitan location. Content analysis of responses developed themes and sub-themes. Results. Of 39 doctors and 32 nurses responding to email invitation, 20 doctors and 16 nurses were interviewed. Major themes were resources/environment, staff and patient issues. Clinicians noted lack of access in rural areas to psychiatric support services, especially alcohol and drug services, limited referral options, and a lack of knowledge, understanding and acceptance of mental health issues. The clinicians suggested resource, education and guideline improvements, wanting better access to mental health experts in rural areas, better support networks and visiting specialist coverage, and educational courses tailored to the needs of rural clinicians. Conclusion. Clinicians managing mental health patients in rural and remote Australian EDs lack resources, support services and referral capacity, and access to appropriate education and training. Improvements would better enable access to support and referral services, and educational opportunities

    First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Angular Power Spectrum

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    We present the angular power spectrum derived from the first-year Wilkinson Microwave Anisotropy Probe (WMAP) sky maps. We study a variety of power spectrum estimation methods and data combinations and demonstrate that the results are robust. The data are modestly contaminated by diffuse Galactic foreground emission, but we show that a simple Galactic template model is sufficient to remove the signal. Point sources produce a modest contamination in the low frequency data. After masking ~700 known bright sources from the maps, we estimate residual sources contribute ~3500 uK^2 at 41 GHz, and ~130 uK^2 at 94 GHz, to the power spectrum l*(l+1)*C_l/(2*pi) at l=1000. Systematic errors are negligible compared to the (modest) level of foreground emission. Our best estimate of the power spectrum is derived from 28 cross-power spectra of statistically independent channels. The final spectrum is essentially independent of the noise properties of an individual radiometer. The resulting spectrum provides a definitive measurement of the CMB power spectrum, with uncertainties limited by cosmic variance, up to l~350. The spectrum clearly exhibits a first acoustic peak at l=220 and a second acoustic peak at l~540 and it provides strong support for adiabatic initial conditions. Kogut et al. (2003) analyze the C_l^TE power spectrum, and present evidence for a relatively high optical depth, and an early period of cosmic reionization. Among other things, this implies that the temperature power spectrum has been suppressed by \~30% on degree angular scales, due to secondary scattering.Comment: One of thirteen companion papers on first-year WMAP results submitted to ApJ; 44 pages, 14 figures; a version with higher quality figures is also available at http://lambda.gsfc.nasa.gov/product/map/map_bibliography.htm

    A novel IEF peptide fractionation method reveals a detailed profile of N-terminal Acetylation in chemotherapy-responsive and -resistant ovarian cancer cells

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    Although acetylation is regarded as a common protein modification, a detailed proteome wide profile of this posttranslational modification may reveal important biological insight regarding differential acetylation of individual proteins. Here we optimised a novel peptide IEF fractionation method for use prior to LC-MS/MS analysis in order to obtain a more in depth coverage of N-terminally acetylated proteins from complex samples. Application of the method to the analysis of the serous ovarian cancer cell line OVCAR-5 identified 341 N-terminally acetylated proteins, 23 of which are previously un-reported. The protein peptidyl-prolyl cis-trans isomerase A (PPIA) was detected in both the N-terminally acetylated and un-modified forms, and was further analysed by data independent acquisition in Carboplatin responsive parental OVCAR-5 cells and Carboplatin resistant OVCAR-5 cells. This revealed a higher ratio of un-acetylated to acetylated N-terminal PPIA in the parental compared to the Carboplatin resistant OVCAR-5 cells, and a 4.1-fold increase in PPIA abundance overall in the parental cells relative to Carboplatin-resistant OVCAR-5 cells (P = 0.015). In summary, the novel IEF peptide fractionation method presented here is robust, reproducible, and can be applied to the profiling of N-terminally acetylated proteins. All mass spectrometry data is available as a ProteomeXchange repository (PXD003547).Florian Weiland, Georgia Arentz, Manuela Klingler-Hoffmann, Peter McCarthy, Noor A. Lokman, Gurjeet Kaur, Martin K. Oehler, and Peter Hoffman

    The Wilkinson Microwave Anisotropy Probe (WMAP) Source Catalog

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    We present the list of point sources found in the WMAP 5-year maps. The technique used in the first-year and three-year analysis now finds 390 point sources, and the five-year source catalog is complete for regions of the sky away from the galactic plane to a 2 Jy limit, with SNR > 4.7 in all bands in the least covered parts of the sky. The noise at high frequencies is still mainly radiometer noise, but at low frequencies the CMB anisotropy is the largest uncertainty. A separate search of CMB-free V-W maps finds 99 sources of which all but one can be identified with known radio sources. The sources seen by WMAP are not strongly polarized. Many of the WMAP sources show significant variability from year to year, with more than a 2:1 range between the minimum and maximum fluxes.Comment: 31 pages Latex with 4 embedded figures. Version accepted by the ApJ Supplement

    Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results

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    We present cosmological parameter constraints based on the final nine-year WMAP data, in conjunction with additional cosmological data sets. The WMAP data alone, and in combination, continue to be remarkably well fit by a six-parameter LCDM model. When WMAP data are combined with measurements of the high-l CMB anisotropy, the BAO scale, and the Hubble constant, the densities, Omegabh2, Omegach2, and Omega_L, are each determined to a precision of ~1.5%. The amplitude of the primordial spectrum is measured to within 3%, and there is now evidence for a tilt in the primordial spectrum at the 5sigma level, confirming the first detection of tilt based on the five-year WMAP data. At the end of the WMAP mission, the nine-year data decrease the allowable volume of the six-dimensional LCDM parameter space by a factor of 68,000 relative to pre-WMAP measurements. We investigate a number of data combinations and show that their LCDM parameter fits are consistent. New limits on deviations from the six-parameter model are presented, for example: the fractional contribution of tensor modes is limited to r<0.13 (95% CL); the spatial curvature parameter is limited to -0.0027 (+0.0039/-0.0038); the summed mass of neutrinos is <0.44 eV (95% CL); and the number of relativistic species is found to be 3.84+/-0.40 when the full data are analyzed. The joint constraint on Neff and the primordial helium abundance agrees with the prediction of standard Big Bang nucleosynthesis. We compare recent PLANCK measurements of the Sunyaev-Zel'dovich effect with our seven-year measurements, and show their mutual agreement. Our analysis of the polarization pattern around temperature extrema is updated. This confirms a fundamental prediction of the standard cosmological model and provides a striking illustration of acoustic oscillations and adiabatic initial conditions in the early universe.Comment: 32 pages, 12 figures, v3: Version accepted to Astrophysical Journal Supplement Series. Includes improvements in response to referee and community; corrected 3 entries in Table 10, (w0 & wa model). See the Legacy Archive for Microwave Background Data Analysis (LAMBDA): http://lambda.gsfc.nasa.gov/product/map/current/ for further detai

    Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Polarization

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    We present a full-sky model of polarized Galactic microwave emission based on three years of observations by the Wilkinson Microwave Anisotropy Probe (WMAP) at frequencies from 23 to 94 GHz. The model compares maps of the Stokes Q and U components from each of the 5 WMAP frequency bands in order to separate synchrotron from dust emission, taking into account the spatial and frequency dependence of the synchrotron and dust components. This simple two-component model of the interstellar medium accounts for at least 97% of the polarized emission in the WMAP maps of the microwave sky. Synchrotron emission dominates the polarized foregrounds at frequencies below 50 GHz, and is comparable to the dust contribution at 65 GHz. The spectral index of the synchrotron component, derived solely from polarization data, is -3.2 averaged over the full sky, with a modestly flatter index on the Galactic plane. The synchrotron emission has mean polarization fraction 2--4% in the Galactic plane and rising to over 20% at high latitude, with prominent features such as the North Galactic Spur more polarized than the diffuse component. Thermal dust emission has polarization fraction 1% near the Galactic center, rising to 6% at the anti-center. Diffuse emission from high-latitude dust is also polarized with mean fractional polarization 0.036 +/- 0.011.Comment: 9 pages with 8 figures. For higher quality figures, see the version posted at http://lambda.gsfc.nasa.gov/product/map/dr2/map_bibliography.cf

    Five-Year Wilkinson Microwave Anisotropy Probe Observations: Source Catalog

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    We present the list of point sources found in the Wilkinson Microwave Anisotropy Probe (WMAP) five-year maps. The technique used in the first-year and three-year analyses now finds 390 point sources, and the five-year source catalog is complete for regions of the sky away from the Galactic plane to a 2 Jy limit, with SNR > 4.7 in all bands in the least covered parts of the sky. The noise at high frequencies is still mainly radiometer noise, but at low frequencies the cosmic microwave background (CMB) anisotropy is the largest uncertainty. A separate search of CMB-free V-W maps finds 99 sources of which all but one can be identified with known radio sources. The sources seen by WMAP are not strongly polarized. Many of the WMAP sources show significant variability from year to year, with more than a 2: 1 range between the minimum and maximum fluxes.NASA NNG05GE76G, NNX07AL75G S01, LTSA03-000-0090, ATPNNG04GK55G, ADP03-0000-092Astronom
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