Bail-Out or Work-Out? Theoretical Considerations

In recent years, we appear to have entered an era of capital account crises. In response, a number of new crisis resolution ideas have been put forward, including the establishment of supranational institutions such as an international lender of last resort or an international bankruptcy court, temporary payments standstills and the inclusion of collective action clauses in debt contracts. This paper assesses these proposals using a theoretical model of crisis. The model underscores the importance of adapting policy interventions to the nature of the crisis at hand. For example, it finds that payments standstills and last-resort lending are an equally efficient means of dealing with liquidity crises, both ex-ante and ex-post, while creditor committees are second-best. It finds that debt-write-downs are a preferred means of dealing with solvency crises than subsidized IMF financing because of the negative moral hazard implications of the latter tool. And it finds that international bankruptcy court proposals may be superior to contractual approaches in securing such write-downscrisis resolution, international lender of last resort, standstills, IMF

Ca II triplet spectroscopy of RGB stars in NGC 6822: kinematics and metallicities

We present a detailed analysis of the chemistry and kinematics of red giants in the dwarf irregular galaxy NGC 6822. Spectroscopy at 8500 Angstroms was acquired for 72 red giant stars across two fields using FORS2 at the VLT. Line of sight extinction was individually estimated for each target star to accommodate the variable reddening across NGC 6822. The mean radial velocity was found to be v_helio = (52.8 +/- 2.2) km/s with dispersion rms = 24.1 km/s, in agreement with other studies. Ca II triplet equivalent widths were converted into [Fe/H] metallicities using a V magnitude proxy for surface gravity. The average metallicity was [Fe/H] = (-0.84 +/- 0.04) with dispersion rms = 0.31 dex and interquartile range 0.48. Our assignment of individual reddening values makes our analysis more sensitive to spatial variations in metallicity than previous studies. We divide our sample into metal-rich and metal-poor stars; the former are found to cluster towards small radii with the metal-poor stars more evenly distributed across the galaxy. The velocity dispersion of the metal-poor stars is higher than that of the metal-rich stars; combined with the age-metallicity relation this indicates that older populations have either been dynamically heated or were born in a less disclike distribution. The low ratio (v_rot/v_rms) suggests that within the inner 10', NGC 6822's stars are dynamically decoupled from the HI gas, possibly in a thick disc or spheroid.Comment: 15 pages, 12 figures, includes tabular dat

An empirical calibration to estimate cool dwarf fundamental parameters from H-band spectra

Interferometric radius measurements provide a direct probe of the fundamental parameters of M dwarfs, but is within reach for only a limited sample of nearby, bright stars. We use interferometrically-measured radii, bolometric luminosities, and effective temperatures to develop new empirical calibrations based on low-resolution, near-infrared spectra. We use H-band Mg and Al features to derive calibrations for effective temperature, radius and log luminosity; the standard deviations in the residuals of our best fits are, respectively, 73K, 0.027Rsun, and 0.049 dex (11% error on luminosity). These relationships are valid for mid K to mid M dwarf stars, roughly corresponding to temperatures between 3100 and 4800K. We apply our calibrations to M dwarfs targeted by the MEarth transiting planet survey and to the cool Kepler Objects of Interest (KOIs). We independently validate our calibrations by demonstrating a clear relationship between our inferred parameters and the absolute K magnitudes of the MEarth stars, and we identify objects with magnitudes too bright for their estimated luminosities as candidate multiple systems. We also use our inferred luminosities to address the applicability of near-infrared metallicity calibrations to mid and late M dwarfs. The temperatures we infer for the KOIs agree remarkably well with those from the literature; however, our stellar radii are systematically larger than those presented in previous works that derive radii from model isochrones. This results in a mean planet radius that is 15% larger than one would infer using the stellar properties from recent catalogs. Our results confirm those of previous in-depth studies of Kepler-42, Kepler-45, and Kepler-186.Comment: Accepted to ApJ. Tables 4 and 5, and machine readable versions of Tables 5 and 7 are available in the ApJ journal articl

Memory and mutualism in species sustainability: a time-fractional Lotka-Volterra model with harvesting

We first present a predator-prey model for two species and then extend the model to three species where the two predator species engage in mutualistic predation. Constant effort harvesting and the impact of by-catch issue are also incorporated. Necessary sufficient conditions for the existence and stability of positive equilibrium points are examined. It is shown that harvesting is sustainable, and the memory concept of the fractional derivative damps out oscillations in the population numbers so that the system as a whole settles on an equilibrium quicker than it would with integer time derivatives. Finally, some possible physical explanations are given for the obtained results. It is shown that the stability requires the memory concept in the model

Pediatric Emergency Preparedness for Natural Disasters, Terrorism, and Public Health Emergencies: A National Consensus Conference: 2009 Update

This is the third consensus document in an ongoing process to convene experts from the multiple disciplines that are involved in the planning for children affected by disasters

Pediatric Emergency Preparedness for Natural Disasters, Terrorism, and Public Health Emergencies: A National Consensus Conference: 2009 Update

This is the third consensus document in an ongoing process to convene experts from the multiple disciplines that are involved in the planning for children affected by disasters

Removal of Perchloroethylene within a Silt Confining Layer Using Hydrogen Release Compound

The Site is a former dry cleaning operation where a release of perchloroethylene (PCE) to soil and groundwater had occurred. Hydrogen Release Compound® (HRC) is being used for source control to mitigate vapor intrusion to the existing building. The Site is located in the Connecticut River basin with PCE up to 250 mg/L in perched groundwater above a silt-layer aquitard. Site risk is driven by the soil vapor intrusion pathway into the commercial building. Soil vapor extraction was implemented to mitigate vapor intrusion, with no appreciable change in the perched groundwater conditions and rapid rebound of PCE in soil gas to pre-treatment levels in four months. Our evaluation of soil data following multiple HRC applications over an 8-year period into the perched groundwater on top of a Connecticut River basin silt deposit finds that treatment in the sandy unit above the aquitard achieved significant reduction of PCE in the silt layer below. This discovery changed the project Conceptual Site Model and led to further evaluation of the source of PCE feeding into soil gas. With decreased groundwater concentrations of PCE but persistent soil gas concentrations, Membrane Interface Probe (MIP) work was done to further assess the extent of additional area within the perched groundwater that required treatment. The results indicated that the extent of significant concentrations of PCE was in a peripheral area around the initial treatment zones. Following the MIP results, additional in-situ HRC treatment in the perched aquifer over a broader area than previous injections was implemented with the intent of removing a significant mass of PCE. As we expected, there was a PCE source in the silt layer below the treatment area. Subsequent data show further decreases in PCE concentrations measured in perched groundwater and soil gas

Using the Ca II Triplet to Trace Abundance Variations in Individual Red Giant Branch stars in Three Nearby Galaxies

Spectroscopic abundance determinations for stars spanning a Hubble time in age are necessary in order to unambiguously determine the evolutionary histories of galaxies. Using FORS1 in Multi-Object Spectroscopy mode on ANTU (UT1) at the ESO-VLT on Paranal we obtained near infrared spectra from which we measured the equivalent widths of the two strongest Ca II triplet lines to determine metal abundances for a sample of Red Giant Branch stars, selected from ESO-NTT optical (I, V-I) photometry of three nearby, Local Group, galaxies: the Sculptor Dwarf Spheroidal, the Fornax Dwarf Spheroidal and the Dwarf Irregular NGC 6822. The summed equivalent width of the two strongest lines in the Ca II triplet absorption line feature, centered at 8500A, can be readily converted into an [Fe/H] abundance using the previously established calibrations by Armandroff & Da Costa (1991) and Rutledge, Hesser & Stetson (1997). We measured metallicities for 37 stars in Sculptor, 32 stars in Fornax, and 23 stars in NGC 6822, yielding more precise estimates of the metallicity distribution functions for these galaxies than it is possible to obtain photometrically. In the case of NGC 6822, this is the first direct measurement of the abundances of the intermediate-age and old stellar populations. We find metallicity spreads in each galaxy which are broadly consistent with the photometric width of the Red Giant Branch, although the abundances of individual stars do not always appear to correspond to their colour. This is almost certainly predominantly due to a highly variable star formation rate with time in these galaxies, which results in a non-uniform, non-globular-cluster-like, evolution of the Ca/Fe ratio.Comment: Accepted for publication in MNRA