High time resolution observation of the transient event of 5 March 1979

The detection of an intense gamma ray burst with the monitor proportional counter on the HEAO 2 spacecraft is discussed with particular emphasis on the measurement of the time of onset of the event. Based on the mean observed counting rate in the burst and assuming a sharp rise, the uncertainty in the burst onset is found to be + or - 220 microseconds. The time of occurrence was 57124.826908 + or - 0.000220 s UT on March 5, 1979, and the location of the HEAO 2 satellite at this time was latitude 22.15 deg, longitude -27.60 deg at an altitude of 525.0 km

The Complex of Solutions of the Nested Bethe Ansatz. The A_2 Spin Chain

The full set of polynomial solutions of the nested Bethe Ansatz is constructed for the case of A_2 rational spin chain. The structure and properties of these associated solutions are more various then in the case of usual XXX (A_1) spin chain but their role is similar

Why is timing of bird migration advancing when individuals are not?

Recent advances in spring arrival dates have been reported in many migratory species but the mechanism driving these advances is unknown. As population declines are most widely reported in species that are not advancing migration, there is an urgent need to identify the mechanisms facilitating and constraining these advances. Individual plasticity in timing of migration in response to changing climatic conditions is commonly proposed to drive these advances but plasticity in individual migratory timings is rarely observed. For a shorebird population that has significantly advanced migration in recent decades, we show that individual arrival dates are highly consistent between years, but that the arrival dates of new recruits to the population are significantly earlier now than in previous years. Several mechanisms could drive advances in recruit arrival, none of which require individual plasticity or rapid evolution of migration timings. In particular, advances in nest-laying dates could result in advanced recruit arrival, if benefits of early hatching facilitate early subsequent spring migration. This mechanism could also explain why arrival dates of short-distance migrants, which generally return to breeding sites earlier and have greater scope for advance laying, are advancing more rapidly than long-distance migrants

Probabilistic Cross-Identification of Astronomical Sources

We present a general probabilistic formalism for cross-identifying astronomical point sources in multiple observations. Our Bayesian approach, symmetric in all observations, is the foundation of a unified framework for object matching, where not only spatial information, but physical properties, such as colors, redshift and luminosity, can also be considered in a natural way. We provide a practical recipe to implement an efficient recursive algorithm to evaluate the Bayes factor over a set of catalogs with known circular errors in positions. This new methodology is crucial for studies leveraging the synergy of today's multi-wavelength observations and to enter the time-domain science of the upcoming survey telescopes.Comment: Accepted for publication in the Astrophysical Journal, 8 pages, 1 figure, emulateapj w/ apjfont

Gamma-ray transfer and energy deposition in supernovae

Solutions to the energy-independent (gray) radiative transfer equations are compared to results of Monte Carlo simulations of the \Ni\ and \Co\ radioactive decay \GR\ energy deposition in supernovae. The comparison shows that an effective, purely absorptive, gray opacity, \KG\ \sim (0.06 \pm 0.01)Y_e cm^2 g^{-1}, where Y_e is the total number of electrons per baryon, accurately describes the interaction of \GRs\ with the cool supernova gas and the local \GR\ energy deposition within the gas. The nature of the \GR\ interaction process (dominated by Compton scattering in the relativistic regime) creates a weak dependence of \KG\ on the optical thickness of the (spherically symmetric) supernova atmosphere: The maximum value of \KG\ applies during optically thick conditions when individual \GRs\ undergo multiple scattering encounters and the lower bound is reached at the phase characterized by a total Thomson optical depth to the center of the atmosphere \te\ \LA\ 1. Our results quantitatively confirm that the quick and efficient solution to the gray transfer problem provides an accurate representation of \GR\ energy deposition for a broad range of supernova conditions

Some Properties of the Calogero-Sutherland Model with Reflections

We prove that the Calogero-Sutherland Model with reflections (the BC_N model) possesses a property of duality relating the eigenfunctions of two Hamiltonians with different coupling constants. We obtain a generating function for their polynomial eigenfunctions, the generalized Jacobi polynomials. The symmetry of the wave-functions for certain particular cases (associated to the root systems of the classical Lie groups B_N, C_N and D_N) is also discussed.Comment: 16 pages, harvmac.te

Discovery of Extreme Examples of Superclustering in Aquarius

We report the discovery of two highly extended filaments and one extremely high density knot within the region of Aquarius. The supercluster candidates were chosen via percolation analysis of the Abell and ACO catalogs and include only the richest clusters (R >= 1). The region examined is a 10x45 degree strip and is now 87% complete in cluster redshift measurements to mag_10 = 18.3. In all, we report 737 galaxy redshifts in 46 cluster fields. One of the superclusters, dubbed Aquarius, is comprised of 14 Abell/ACO clusters and extends 110h^-1Mpc in length only 7 degrees off the line-of-sight. On the near-end of the Aquarius filament, another supercluster, dubbed Aquarius-Cetus, extends for 75h^-1Mpc perpendicular to the line-of-sight. After fitting ellipsoids to both Aquarius and Aquarius-Cetus, we find axis ratios (long-to- midlength axis) of 4.3 for Aquarius and 3.0 for Aquarius-Cetus. We fit ellipsoids to all N>=5 clumps of clusters in the Abell/ACO measured-z cluster sample. The frequency of filaments with axis ratios >=3.0 (~20%) is nearly identical with that found among `superclusters' in Monte Carlo simulations of random and random- clumped clusters, however, so the rich Abell/ACO clusters have no particular tendency toward filamentation. The Aquarius filament also contains a `knot' of 6 clusters at Z ~0.11, with five of the clusters near enough togeteher to represent an apparent overdensity of 150. There are three other R >= 1 cluster density enhancements similar to this knot at lower redshifts: Corona Borealis, the Shapely Concentration, and another grouping of seven clusters in Microscopium. All four of these dense superclusters appear near the point of breaking away from the Hubble Flow, and some may now be in collapse, but there is little evidence of any being virialized.Comment: 45 pages (+ e-tables), 7 figures, AASTeX Accepted for Publication in Ap

Starburst Galaxies: Why the Calzetti Dust Extinction Law?

The empirical reddening function for starburst galaxies generated by Calzetti and her co-workers has proven very successful, and is now used widely in the observational literature. Despite its success, however, the physical basis for this extinction law, or more correctly, attenuation law remains weak. Here we provide a physical explanation for the Calzetti Law based on a turbulent interstellar medium. In essence, this provides a log-normal distribution of column densities, giving a wide range of column densities in the dusty foreground screen. Therefore, extended sources such as starburst regions or HII regions seen through it suffer a point-to-point stochastic extinction and reddening. Regions of high column densities are "black" in the UV, but translucent in the IR, which leads to a flatter extinction law, and a larger value of the total to selective extinction, R_V. We fit the Calzetti Law, and infer that the variance sigma of the log-normal distribution lies in the range 0.6<sigma<2.2. The absolute to selective extinction R_V is found to be in the range 4.3 to 5.2 consistent with R_V=4.05+/-0.80 of the Calzetti Law.Comment: accepted for publication in ApJ

Artesunate reduces but does not prevent posttreatment transmission of Plasmodium falciparum to Anopheles gambiae.

Combination therapy that includes artemisinin derivatives cures most falciparum malaria infections. Lowering transmission by reducing gametocyte infectivity would be an additional benefit. To examine the effect of such therapy on transmission, Gambian children with Plasmodium falciparum malaria were treated with standard regimens of chloroquine or pyrimethamine-sulfadoxine alone or in combination with 1 or 3 doses of artesunate. The infectivity to mosquitoes of gametocytes in peripheral blood was determined 4 or 7 days after treatment. Infection of mosquitoes was observed in all treatment groups and was positively associated with gametocyte density. The probability of transmission was lowest in those who received pyrimethamine-sulfadoxine and 3 doses of artesunate, and it was 8-fold higher in the group that received pyrimethamine-sulfadoxine alone. Artesunate reduced posttreatment infectivity dramatically but did not abolish it completely. The study raises questions about any policy to use pyrimethamine-sulfadoxine alone as the first-line treatment for malaria