On the kHz QPO frequency correlations in bright neutron star X-ray binaries

We re-examine the correlation between the frequencies of upper and lower kHz quasi-periodic oscillations (QPO) in bright neutron-star low-mass X-ray binaries. By including the kHz QPO frequencies of the X-ray binary Cir X-1 and two accreting millisecond pulsars in our sample, we show that the full sample does not support the class of theoretical models based on a single resonance, while models based on relativistic precession or Alfven waves describe the data better. Moreover, we show that the fact that all sources follow roughly the same correlation over a finite frequency range creates a correlation between the linear parameters of the fits to any sub-sample.Comment: Accepted for publication in MNRAS; 7 pages, 4 figure

Globalization, Urbanization and Nutritional Change in the Developing World

Urbanization and globalization may enhance access to non traditional foods as a result of changing prices and production practices, as well as trade and marketing practices. These forces have influenced dietary patterns throughout the developing world. Longitudinal case study data from China indicate that consumption patterns closely reflect changes in availability, and that potentially obesogenic dietary patterns are emerging, with especially large changes in rural areas with high levels of urban infrastructure and resources. Recent data on women from 36 developing countries illustrate that these dietary shifts may have implications for overweight/obesity in urban and rural settings. These data emphasize the importance of developing country policies that include preventive measures to minimize further adverse shifts in diet and activity, and risk of continued rises in overweight.dietary patterns, developing countries, overweight, food policy, Agricultural and Food Policy, Community/Rural/Urban Development, Food Security and Poverty,

Magnetotunneling in a Two-Dimensional Electron-Hole System Near Equilibrium

We have measured the zero-bias differential tunneling conductance of InAs/AlSb/GaS b/AlSb/InAs heterostructures at low temperatures (1.7K < T < 60K) and unde r a magnetic field at various angles with the heterostructure's interfaces. Shubni kov-de Haas oscillations in the magnetoconductance reveal the two-dimensional (2D) character of the electrons accumulated at the InAs interfaces and yield their num ber in each of them. The temperature dependence of the oscillations suggests the f ormation of a field-induced energy gap at the Fermi level, similar to that observe d before in simpler 2D-2D tunneling systems. A calculation of the magnetoconductan ce that considers different 2D densities in the two InAs electrodes agrees with th e main observations, but fails to explain features that might be related to the pr esence of 2D holes in the GaSb region.Comment: 4 papes, 3 eps figures. Submit to Phys. Rev.

Shear localization as a mesoscopic stress-relaxation mechanism in fused silica glass at high strain rates

Molecular dynamics (MD) simulations of fused silica glass deforming in pressure-shear, while revealing useful insights into processes unfolding at the atomic level, fail spectacularly in that they grossly overestimate the magnitude of the stresses relative to those observed, e. g., in plate-impact experiments. We interpret this gap as evidence of relaxation mechanisms that operate at mesoscopic lengthscales and which, therefore, are not taken into account in atomic-level calculations. We specifically hypothesize that the dominant mesoscopic relaxation mechanism is shear banding. We evaluate this hypothesis by first generating MD data over the relevant range of temperature and strain rate and then carrying out continuum shear-banding calculations in a plate-impact configuration using a critical-state plasticity model fitted to the MD data. The main outcome of the analysis is a knock-down factor due to shear banding that effectively brings the predicted level of stress into alignment with experimental observation, thus resolving the predictive gap of MD calculations

A catalog of planetary nebulae in the elliptical galaxy NGC 4697

We present a catalog of 535 planetary nebulae discovered in the flattened elliptical galaxy NGC 4697, using the FORS1 Cassegrain spectrograph of the Very Large Telescope of the European Southern Observatory at Cerro Paranal, Chile. The catalog provides positions (x, y coordinates relative to the center of light of NGC 4697, as well as RA, Dec.), and, for almost all PNs, the magnitude m(5007) and the heliocentric radial velocity in km/s.Comment: 16 pages, 5 figures, ApJS in pres