Direct Detection of Planets Orbiting Large Angular Diameter Stars: Sensitivity of an Internally Occulting Space-based Coronagraph

High-contrast imaging observations of large angular diameter stars enable complementary science questions to be addressed compared to the baseline goals of proposed missions like the Terrestrial Planet Finder-Coronagraph, New World's Observer, and others. Such targets, however, present a practical problem in that finite stellar size results in unwanted starlight reaching the detector, which degrades contrast. In this paper, we quantify the sensitivity, in terms of contrast, of an internally occulting, space-based coronagraph as a function of stellar angular diameter, from unresolved dwarfs to the largest evolved stars. Our calculations show that an assortment of band-limited image masks can accommodate a diverse set of observations to help maximize mission scientific return. We discuss two applications based on the results: the spectro-photometric study of planets already discovered with the radial velocity technique to orbit evolved stars, which we elucidate with the example of Pollux b, and the direct detection of planets orbiting our closest neighbor, α Centauri, whose primary component is on the main sequence but subtends an appreciable angle on the sky. It is recommended that similar trade studies be performed with other promising internal, external, and hybrid occulter designs for comparison, as there is relevance to a host of interesting topics in planetary science and related fields

Has Korean Manufacturing Production Reached its Full Potential?

This paper sheds some light on the relevance of the assimilation view for South Korea, whereby successful mastering of foreign technology in its adoption and use would lead to firms producing at their full potential output. This is investigated by studying the technical efficiency performance of firms in four manufacturing industries using firm-level data from 1980-94 and applying the random coefficient frontier model. Empirical results show that the assimilation view holds true in the heavy industries but not in the light industries. Although the rate of technical efficiency varied within the two industries, the variation was statistically significant only for firms in the heavy industries since the late 1980s

Transitions to Nematic states in homogeneous suspensions of high aspect ratio magnetic rods

Isotropic-Nematic and Nematic-Nematic transitions from a homogeneous base state of a suspension of high aspect ratio, rod-like magnetic particles are studied for both Maier-Saupe and the Onsager excluded volume potentials. A combination of classical linear stability and asymptotic analyses provides insight into possible nematic states emanating from both the isotropic and nematic non-polarized equilibrium states. Local analytical results close to critical points in conjunction with global numerical results (Bhandar, 2002) yields a unified picture of the bifurcation diagram and provides a convenient base state to study effects of external orienting fields.Comment: 3 Figure

Refining Exoplanet Ephemerides and Transit Observing Strategies

Transiting planet discoveries have yielded a plethora of information regarding the internal structure and atmospheres of extra-solar planets. These discoveries have been restricted to the low-periastron distance regime due to the bias inherent in the geometric transit probability. Monitoring known radial velocity planets at predicted transit times is a proven method of detecting transits, and presents an avenue through which to explore the mass-radius relationship of exoplanets in new regions of period/periastron space. Here we describe transit window calculations for known radial velocity planets, techniques for refining their transit ephemerides, target selection criteria, and observational methods for obtaining maximum coverage of transit windows. These methods are currently being implemented by the Transit Ephemeris Refinement and Monitoring Survey (TERMS).Comment: 8 pages, 6 figures, accepted for publication in PAS

Thermal Bremsstrahlung Radiation in a Two-Temperature Plasma

In the normal one-temperature plasma the motion of ions is usually neglected when calculating the Bremsstrahlung radiation of the plasma. Here we calculate the Bremsstrahlung radiation of a two-temperature plasma by taking into account of the motion of ions. Our results show that the total radiation power is always lower if the motion of ions is considered. We also apply the two-temperature Bremsstrahlung radiation mechanism for an analytical Advection-Dominated Accretion Flow (ADAF) model; we find the two-temperature correction to the total Bremsstrahlung radiation for ADAF is negligible.Comment: 5 pages, 4 figures, accepted for publication in CHJAA. Some discussions and references adde

System Geometries and Transit / Eclipse Probabilities

Transiting exoplanets provide access to data to study the mass-radius relation and internal structure of extrasolar planets. Long-period transiting planets allow insight into planetary environments similar to the Solar System where, in contrast to hot Jupiters, planets are not constantly exposed to the intense radiation of their parent stars. Observations of secondary eclipses additionally permit studies of exoplanet temperatures and large-scale exo-atmospheric properties. We show how transit and eclipse probabilities are related to planet-star system geometries, particularly for long-period, eccentric orbits. The resulting target selection and observational strategies represent the principal ingredients of our photometric survey of known radial-velocity planets with the aim of detecting transit signatures (TERMS).Comment: 3 pages, 2 figures. Comments: To appear in the ASP Conference Proceedings: Detection and Dynamics of Transiting Exoplanets; Proceedings of Haute Provence Observatory Colloquium (23-27 August 2010); Edited by F. Bouchy, R. F. Diaz, and C. Mouto

Minimum inhibitory concentration of drugs against Mycobacterium leprae as determined by anin vitro assay

The observations that liveMycobacterium leprae after entry into cultured peritoneal macrophages from mice, reduced the EA rosetting macrophages, have been exploited to determine the minimum inhibitory concentration of diamino diphenyl sulphone and rifampicin. Diamino diphenyl sulphone showed a minimum inhibitory concentration of 0.028 μg/ml and rifampicin 0.11μg/ml when given externally. However, there was accumulation of diamino diphenyl sulphone inside the macrophages. At an external concentration of 0.028 μg/ml the concentration inside the macrophage was 0.5μg/ml. The minimum inhibitory concentration for diamino diphenyl sulphone in this assay system is higher by several folds and that for rifampicin is slightly lower, than what is reported earlier with mice foot pad experiments. The minimum inhibitory concentration reported in this assay system is quite close to what is observed forin vitro inhibition ofMycobacterium lufu with both the drug