Nonthermal Radiation from Type Ia Supernova Remnants

We present calculations of expected continuum emissions from Sedov-Taylor phase Type Ia supernova remnants (SNRs), using the energy spectra of cosmic ray (CR) electrons and protons from nonlinear diffusive shock acceleration (DSA) simulations. A new, general-purpose radiative process code, Cosmicp, was employed to calculate the radiation expected from CR electrons and protons and their secondary products. These radio, X-ray and gamma-ray emissions are generally consistent with current observations of Type Ia SNRs. The emissions from electrons in these models dominate the radio through X-ray bands. Decays of \pi^0 s from p-p collisions mostly dominate the gamma-ray range, although for a hot, low density ISM case (n_{ISM}=0.003 cm^{-3}), the pion decay contribution is reduced sufficiently to reveal the inverse Compton contribution to TeV gamma-rays. In addition, we present simple scalings for the contributing emission processes to allow a crude exploration of model parameter space, enabling these results to be used more broadly. We also discuss the radial surface brightness profiles expected for these model SNRs in the X-ray and gamma-ray bands.Comment: 37 pages, 7 figures, accepted in MNRA

Water vapor and the dynamics of climate changes

Water vapor is not only Earth's dominant greenhouse gas. Through the release of latent heat when it condenses, it also plays an active role in dynamic processes that shape the global circulation of the atmosphere and thus climate. Here we present an overview of how latent heat release affects atmosphere dynamics in a broad range of climates, ranging from extremely cold to extremely warm. Contrary to widely held beliefs, atmospheric circulation statistics can change non-monotonically with global-mean surface temperature, in part because of dynamic effects of water vapor. For example, the strengths of the tropical Hadley circulation and of zonally asymmetric tropical circulations, as well as the kinetic energy of extratropical baroclinic eddies, can be lower than they presently are both in much warmer climates and in much colder climates. We discuss how latent heat release is implicated in such circulation changes, particularly through its effect on the atmospheric static stability, and we illustrate the circulation changes through simulations with an idealized general circulation model. This allows us to explore a continuum of climates, constrain macroscopic laws governing this climatic continuum, and place past and possible future climate changes in a broader context.Comment: 22 pages, 11 figure

Multidimensional diffusive shock acceleration in the winds from massive stars

<p>Nonthermal radio emission has been seen in the winds around a quarter of all O-stars. The emission is attributed to shock accelerated cosmic rays. The shocks thought to be causing the acceleration are either wind-embedded shocks due to radiative line driving instabilities in the stellar wind, or shocks due to the colliding winds in a binary system. Very few numerical Diffusive Shock Acceleration (DSA) simulations exist for these systems due to the complicated, multidimensional nature of the winds. We present the first 2-D magnetohydrodynamic DSA (MHD-DSA) simulations of massive stellar winds using the Multidimensional Adaptive Subcycling Tridiagonal solver (MAST), which has been incorporated into the WOMBAT (sWift Objects for Mhd BAsed on Tvd) code to solve diffusive shock acceleration for cosmic rays. Shock modification due to cosmic ray pressure is shown to be important in describing the shock dynamics of the colliding wind binary scenario. With 10-4 of the gas particles passing through the shocks being injected as cosmic rays, about 15% of the wind ram pressure is converted into cosmic ray pressure. In the wind-embedded shock scenario, the isothermal conditions in the wind, due to radiative heating and cooling, precluded inclusion of cosmic ray feedback. Future 1-D simulations of cosmic ray modified radiative shocks are suggested, as the combined effects of radiative line cooling and cosmic ray feedback dramatically change the shock dynamics from adiabatic analogues. Both cases show efficient cosmic ray acceleration. In the case of the wind-embedded shocks, the isothermal nature of the wind creates shocks capable of accelerating electrons up to 100 MeV and protons up to 1 GeV with a spectral slope of 4. The colliding wind binary scenario produces very strong shocks which are capable of accelerating electrons up 1 GeV and protons up to 1 TeV with a spectral slope of 4. While full radiation models will be performed in the future, preliminary estimates indicate that the radio emission from the wind-embedded shock scenario may be extinguished due to free-free absorption. This would exclude the wind-embedded shock scenario from being able to explain the observed radio emission.</p

Fibre Bragg grating based effective soil pressure sensor for geotechnical applications

An effective-soil-pressure sensor for geotechnical applications based on Fibre Bragg Gratings is presented. The sensor simultaneous measures total soil pressure and pore pressure, allowing the calculation of the effective stress of soil. Calibration of the sensor using pressurised air demonstrated a pressure sensitivity of 2.02x10 ± 2.84x10nm/kPa and 1.87x10 ± 6.88x10nm/kPa for the total and pore pressure respectively. This corresponds to a pressure resolution of 4.95x10 kPa and 5.46x10kPa for total and pore pressure using a 1pm interrogation system. Measurements undertaken in two types of soil demonstrated dependence of the total pressure sensitivity on soil density/stiffness. Pore pressure measurements agreed well with the preliminary calibrati

Assessment of postprandial triglycerides in clinical practice: Validation in a general population and coronary heart disease patients.

Previous studies have suggested that for clinical purposes, subjects with fasting triglycerides (TGs) between 89-180 mg/dl (1-2 mmol/l) would benefit from postprandial TGs testing. To determine the postprandial TG response in 2 independent studies and validate who should benefit diagnostically from an oral-fat tolerance test (OFTT) in clinical practice. A population of 1002 patients with coronary heart disease (CHD) from the CORDIOPREV clinical trial and 1115 white US subjects from the GOLDN study underwent OFTTs. Subjects were classified into 3 groups according to fasting cut points of TGs to predict the usefulness of OFTT: (1) TG  180 mg/dl (>2 mmol/l). Postprandial TG concentration at any point > 220 mg/dl (>2.5 mmol/l) has been pre-established as an undesirable postprandial response. Of the total, 49% patients with CHD and 42% from the general population showed an undesirable response after the OFTT. The prevalence of undesirable postprandial TG in the CORDIOPREV clinical trial was 12.8, 50.3, and 89.7%, in group 1, 2, and 3, respectively (P  These two studies validate the predictive values reported in a previous consensus. Moreover, the findings of the CORDIOPREV and GOLDN studies show that an OFTT is useful to identify postprandial hyperlipidemia in subjects with fasting TG between 1-2 mmol/l (89-180 mg/dL), because approximately half of them have hidden postprandial hyperlipidemia, which may influence treatment. An OFTT does not provide additional information regarding postprandial hyperlipidemia in subjects with low TG (2 mmol/l, >180 mg/dl)