A Sensitive Moving-Coil Galvanometer

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EGRET Observations of the Diffuse Gamma-Ray Emission in Orion: Analysis Through Cycle 6

We present a study of the high-energy diffuse emission observed toward Orion by the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma-Ray Observatory. The total exposure by EGRET in this region has increased by more than a factor of two since a previous study. A simple model for the diffuse emission adequately fits the data; no significant point sources are detected in the region studied ($l = 195^\circ$ to $220^\circ$ and $b = -25^\circ to -10^\circ$) in either the composite dataset or in two separate groups of EGRET viewing periods considered. The gamma-ray emissivity in Orion is found to be $(1.65 \pm 0.11) \times 10^{-26} {s sr}^{-1}$ for E > 100 MeV, and the differential emissivity is well-described as a combination of contributions from cosmic-ray electrons and protons with approximately the local density. The molecular mass calibrating ratio is $N(H_2)/W_{CO} = (1.35 \pm 0.15) \times 10^{20} cm^{-2} (K km/s)^{-1}$.Comment: 16 pages, including 5 figures. 3 Tables as three separate files. Latex document, needs AASTEX style files. Accepted for publication in Ap

Tradeoff between short-term and long-term adaptation in a changing environment

We investigate the competition dynamics of two microbial or viral strains that live in an environment that switches periodically between two states. One of the strains is adapted to the long-term environment, but pays a short-term cost, while the other is adapted to the short-term environment and pays a cost in the long term. We explore the tradeoff between these alternative strategies in extensive numerical simulations, and present a simple analytic model that can predict the outcome of these competitions as a function of the mutation rate and the time scale of the environmental changes. Our model is relevant for arboviruses, which alternate between different host species on a regular basis.Comment: 9 pages, 3 figures, PRE in pres

A trivial observation on time reversal in random matrix theory

It is commonly thought that a state-dependent quantity, after being averaged over a classical ensemble of random Hamiltonians, will always become independent of the state. We point out that this is in general incorrect: if the ensemble of Hamiltonians is time reversal invariant, and the quantity involves the state in higher than bilinear order, then we show that the quantity is only a constant over the orbits of the invariance group on the Hilbert space. Examples include fidelity and decoherence in appropriate models.Comment: 7 pages 3 figure

Training Effects on Emergency Management Activation Response

Emergency management personnel play an important role in keeping our citizens safe. This study considered whether local and long-term emergency management training could produce different behavioral reactions to severe weather situations. Results indicate a significant positive effect for both long-term and local training on emergency management behavioral response. Individuals with higher levels of training initiated a significantly higher proportion of emergency response activation. Discussion centers on the notion that while these results indicate training has an effect on behavioral reaction, quantity of training rather than the specific type of training was most important

X-ray imaging of the Seyfert 2 galaxy Circinus with Chandra

We present results from the zeroth-order imaging of a Chandra HETGS observation of the nearby Seyfert 2 galaxy Circinus. Twelve X-ray sources were detected in the ACIS-S image of the galaxy, embedded in diffuse X-ray emission. The latter shows a prominent (~18arcsec) soft ``plume'' in the N-W direction, coincident with the [OIII] ionization cone. The radial profiles of the brightest X-ray source at various energies are consistent with an unresolved (FWHM ~0.8arcsec) component, which we identify as the active nucleus, plus two extended components with FWHMs ~ 2.3arcsec and 18arcsec, respectively. In a radius of 3arcsec, the nucleus contributes roughly the same flux as the extended components at the softest energies (< 2 keV). However, at harder energies (> 2 keV), the contribution of the nucleus is dominant. The zeroth-order ACIS spectrum of the nucleus exhibits emission lines at both soft and hard X-rays, including a prominent Fe Kalpha line at 6.4 keV, showing that most of the X-ray lines previously detected with ASCA originate in a compact region (<15 pc). Based on its X-ray spectrum, we argue that the 2.3arcsec extended component is scattered nuclear radiation from nearby ionized gas. The large-scale extended component includes the emission from the N-W plume and possibly from the outer starburst ring.Comment: Figure 1 in color. ApJ Letters, in pres

An S2 Fluorescence Model for Interpreting High-Resolution Cometary Spectra. I. Model Description and Initial Results

A new versatile model providing S2 fluorescence spectrum as a function of time is developed with the aim of interpreting high resolution cometary spectra. For the S2 molecule, it is important to take into account both chemical and dynamic processes because S2 has a short lifetime and is confined in the inner coma where these processes are most important. The combination of the fluorescence model with a global coma model allows for the comparison with observations of column densities taken through an aperture and for the analysis of S2 fluorescence in different parts of the coma. Moreover, the model includes the rotational structure of the molecule. Such a model is needed for interpreting recent high spectral resolution observations of cometary S2. A systematic study of the vibrational-rotational spectrum of S2 is undertaken, including relevant effects, such as non-equilibrium state superposition and the number density profile within the coma due to dynamics and chemistry, to investigate the importance of the above effects on the scale length and abundance of S2 in comets.Comment: 20 pages, 7 figure

Spitzer observations of the asteroid-comet transition object and potential spacecraft target 107P (4015) Wilson-Harrington

Context. Near-Earth asteroid-comet transition object 107P/ (4015) Wilson-Harrington is a possible target of the joint European Space Agency (ESA) and Japanese Aerospace Exploration Agency (JAXA) Marco Polo sample return mission. Physical studies of this object are relevant to this mission, and also to understanding its asteroidal or cometary nature. Aims. Our aim is to obtain significant new constraints on the surface thermal properties of this object. Methods. We present mid-infrared photometry in two filters (16 and 22 microns) obtained with NASA's Spitzer Space Telescope on February 12, 2007, and results from the application of the Near Earth Asteroid Thermal Model (NEATM).We obtained high S/N in two mid-IR bands allowing accurate measurements of its thermal emission. Results. We obtain a well constrained beaming parameter (eta = 1.39 +/- 0.26) and obtain a diameter and geometric albedo of D = 3.46 +/- 0.32 km, and pV = 0.059 +/- 0.011. We also obtain similar results when we apply this best-fitting thermal model to single-band mid-IR photometry reported by Campins et al. (1995), Kraemer et al. (2005) and Reach et al. (2007). Conclusions. The albedo of 4015 Wilson-Harrington is low, consistent with those of comet nuclei and primitive C-, P-, D-type asteorids. We establish a rough lower limit for the thermal inertia of W-H of 60 Jm^-2s^(-0.5)K^-1 when it is at r=1AU, which is slightly over the limit of 30 Jm^-2s^(-0.5)K-1 derived by Groussin et al. (2009) for the thermal inertia of the nucleus of comet 22P/Kopff.Comment: 4 pages, 1 figure and 3 tables. Paper accepted for publicatio