Conditional Analysis of an Internal Boundary Layer

Data from a convective internal boundary layer (IBL) are analyzed by focusing on the instantaneousstructure of the top of the IBL instead of the time-average structure.A conditional averaging technique is developed todiscriminate between air from above the IBL and air from below the IBL , which alternately invade some instrument levels due tosubstantial variation of the top of the convective IBL.Sensitivity to the conditional sampling criteria is examined.Inside the IBL , buoyant and mechanicalproduction and dissipation dominate the turbulent kinetic energy budget.The horizontal advection and turbulent transport terms are smaller, but not negligible. The inferred pressure correlation term is negligible.Above the IBL , buoyant production and dissipation, although weak,dominate the turbulent kinetic energy budget. Shear generation andturbulent transport are smaller but significant.     

Swift observations of CSS081007:030559+054715

CSS081007:030559+054715 was discovered by the Catalina Real‐time Transient Survey. Optical spectroscopy revealed a multi‐peaked Hα emission line profile with radial velocities exceeding 1500 km/s, as well as strong Ne emission, suggestive of a neon nova. We monitored the source extensively with the Swift satellite, obtaining a unique dataset spanning 270 days in the soft X‐ray and UV bands. The data reveal a soft, blackbody‐like spectrum with a temperature around 55 eV (though dependent on the modelling), variable X‐ray and UV light curves with a 1.77 day period in both the X‐ray and UV bands, a longer timescale modulation of ∼ 50 days, followed by a slowly declining trend in the soft X‐ray and UV flux. We highlight the Swift observations and their implications for the SSS nature of this object (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Cooling of neutron stars with strong toroidal magnetic fields

We present models of temperature distribution in the crust of a neutron star in the presence of a strong toroidal component superposed to the poloidal component of the magnetic field. The presence of such a toroidal field hinders heat flow toward the surface in a large part of the crust. As a result, the neutron star surface presents two warm regions surrounded by extended cold regions and has a thermal luminosity much lower than in the case the magnetic field is purely poloidal. We apply these models to calculate the thermal evolution of such neutron stars and show that the lowered photon luminosity naturally extends their life-time as detectable thermal X-ray sources. Work partially supported by UNAM-DGAPA grant #IN119306.     

Climate impact of transportation A model comparison

Transportation contributes to a significant and rising share of global energy use and GHG emissions. Therefore modeling future travel demand, its fuel use, and resulting CO₂ emission is highly relevant for climate change mitigation. In this study we compare the baseline projections for global service demand (passenger-kilometers, ton-kilometers), fuel use, and CO₂ emissions of five different global transport models using harmonized input assumptions on income and population. For four models we also evaluate the impact of a carbon tax. All models project a steep increase in service demand over the century. Technology change is important for limiting energy consumption and CO₂ emissions, the study also shows that in order to stabilise or even decrease emissions radical changes would be required. While all models project liquid fossil fuels dominating up to 2050, they differ regarding the use of alternative fuels (natural gas, hydrogen, biofuels, and electricity), because of different fuel price projections. The carbon tax of 200 USD/tCO₂ in 2050 stabilizes or reverses global emission growth in all models. Besides common findings many differences in the model assumptions and projections indicate room for further understanding long-term trends and uncertainty in future transport systems.     

A Bayesian Approach to Establishing a Reference Particle Size Distribution in the Presence of Outliers

The presence of observations or measurements that are unlike the majority is fairly common in studies conducted to establish particle size (or weight fraction) distributions. Therefore, there is a need to develop methods that are capable of producing estimates of particle size distributions that are not overly sensitive to the presence of a few observations that might be considered outliers. This article proposes a type of contamination mixture model that probabilistically allocates each observation to either a majority component or a contamination component. Observations that are allocated to a contamination component are down-weighted when estimating the particle size distribution (while the uncertainty of contamination classification is automatically accounted for in estimation). Computational methods are developed and the utility of the proposed methodology is demonstrated via a simulation study. The method is then applied to data produced from an inter-laboratory study conducted to establish a particle size distribution in cement.