Steady-state differential calorimeter measures gamma heating in reactor

Steady-state differential calorimeter, which displays good accuracy and reproducibility of results, is used to measure gamma heating in a reactor environment. The calorimeter has a long life expectancy since it is virtually unharmed by the reactor environment

Gas-grain chemistry in cold interstellar cloud cores with a microscopic Monte Carlo approach to surface chemistry

AIM: We have recently developed a microscopic Monte Carlo approach to study surface chemistry on interstellar grains and the morphology of ice mantles. The method is designed to eliminate the problems inherent in the rate-equation formalism to surface chemistry. Here we report the first use of this method in a chemical model of cold interstellar cloud cores that includes both gas-phase and surface chemistry. The surface chemical network consists of a small number of diffusive reactions that can produce molecular oxygen, water, carbon dioxide, formaldehyde, methanol and assorted radicals. METHOD: The simulation is started by running a gas-phase model including accretion onto grains but no surface chemistry or evaporation. The starting surface consists of either flat or rough olivine. We introduce the surface chemistry of the three species H, O and CO in an iterative manner using our stochastic technique. Under the conditions of the simulation, only atomic hydrogen can evaporate to a significant extent. Although it has little effect on other gas-phase species, the evaporation of atomic hydrogen changes its gas-phase abundance, which in turn changes the flux of atomic hydrogen onto grains. The effect on the surface chemistry is treated until convergence occurs. We neglect all non-thermal desorptive processes. RESULTS: We determine the mantle abundances of assorted molecules as a function of time through 2x10^5 yr. Our method also allows determination of the abundance of each molecule in specific monolayers. The mantle results can be compared with observations of water, carbon dioxide, carbon monoxide, and methanol ices in the sources W33A and Elias 16. Other than a slight underproduction of mantle CO, our results are in very good agreement with observations.Comment: 13 pages, 7 figures, to be published in A. &

Why do Local Unemployment Rates in Poland Vary so Much?

Unemployment continues to bedevil Poland, albeit with striking sub-national differences, which this paper seeks to explain using random effects error component two-stage estimation for the country's NUTS 4 level powiats. Given the economy's peculiar configuration under communism, with its large private agricultural sector, emphasis is placed on rural-urban differences. While less densely populated areas do suffer higher unemployment rates, the effect is moderated by hidden unemployment in farming. On the other hand, powiats that housed the ex-state farms suffer a negative long-term legacy. Other notable results include an evident positive impact of foreign capital on local labour market fortunes.

The Arecibo Galaxy Environment Survey VIII : Discovery of an Isolated Dwarf Galaxy in the Local Volume

The Arecibo Galaxy Environment Survey (AGES) has detected a nearby HI source at a heliocentric velocity of +363 km/s . The object was detected through its neutral hydrogen emission and has an obvious possible optical counterpart in Sloan Digital Sky Survey (SDSS) data (though it does not have an optical redshift measurement). We discuss three possible scenarios for the object : 1) It is within the Local Group, in which case its HI properties are comparable with recently discovered ultra-compact high velocity clouds; 2) It is just behind the Local Group, in which case its optical characteristics are similar to the newly discovered Leo P galaxy; 3) It is a blue compact dwarf galaxy within the local volume but not associated with the Local Group. We find the third possibility to be the most likely, based on distance estimates from the Tully-Fisher relation and its velocity relative to the Local Group.Comment: 5 pages, 6 figures, accepted for publication in MNRAS. Minor correction to institution and addres

Thermal Evaluation of High Voltage Hermetic Motors Experiencing Recurrent Insulation Failures

A high voltage hermetic compressor motor design developed for chiller applications has shown recurrent insulation failures in certain stator end-turn regions. Initial investigations found discoloration of failed coil insulation and suggested that the stator coils over heated during operation at rated load. Thermal modeling was conducted to develop an understanding of the causes of the unacceptably high motor failure rate so that corrective actions could be taken for future motor designs. This paper presents thermal modeling efforts for predicting steady-state temperature distributions within the stator coil in the end-turn region under full-load electrical heating and a refrigerant cooling environment. Insulation thermal conductivity and coil surface convection heat transfer coefficient were identified as two critical heat transfer parameters which dictate the effectiveness of coil heat dissipation. Thermal analysis results have been correlated with measured temperature dependent insulation thermal conductivities and stator coil surface temperatures measured in motor cooling tests. The results of thermal evaluation indicate that the premature motor failures are likely caused by excessive conductor heating due to high operating current density in a non-uniform coolant distribution.Center for Electromechanic

New Dissociative Recombination Product Branching Fractions and Their Effect on Calculated Interstellar Molecular Abundances

Recent storage ring measurements of the complete product distributions for the dissociative recombination of assorted polyatomic ions (H_3^+, H_2O^+, H_3O^+, CH_3^+) show that there is significantly more fragmentation than previously believed. Generalizing these results, we consider the effect on gas-phase chemical models of dense interstellar clouds when a greater degree of fragmentation is assumed for the products of dissociative recombination reactions. In general, we find salient model results to be surprisingly insensitive to the change. We also generalize some conflicting experimental results for the branching fractions of H_3O^+ + e obtained in a flowing afterglow experiment. With this set of generalized branching fractions in our chemical model, there is a stronger change from previous results, especially for more saturated molecules, which are now difficult to produce in the gas phase

Profiles of Strong Permitted Lines in Classical T Tauri Stars

We present a spectral analysis of 30 T Tauri stars observed with the Hamilton echelle spectrograph over more than a decade. One goal is to test magnetospheric accretion model predictions. Observational evidence previously published supporting the model, such as emission line asymmetry and a high frequency of redshifted absorption components, are considered. We also discuss the relation between different line forming regions and search for good accretion rate indicators. In this work we confirm several important points of the models, such as the correlation between accretion and outflow, broad emission components that are mostly central or slightly blueshifted and only the occasional presence of redshifted absorption. We also show, however, that the broad emission components supposedly formed in the magnetospheric accretion flow only partially support the models. Unlike the predictions, they are sometimes redshifted, and are mostly found to be symmetric. The published theoretical profiles do not have a strong resemblance to our observed ones. We emphasize the need for accretion models to include a strong turbulent component before their profiles will match the observations. The effects of rotation, and the outflow components, will also be needed to complete the picture.Comment: 25 pages including 9 figures, 3 tables, accepted for publication in the Astronomical Journa

Boundary states, matrix factorisations and correlation functions for the E-models

The open string spectra of the B-type D-branes of the N=2 E-models are calculated. Using these results we match the boundary states to the matrix factorisations of the corresponding Landau-Ginzburg models. The identification allows us to calculate specific terms in the effective brane superpotential of E_6 using conformal field theory methods, thereby enabling us to test results recently obtained in this context.Comment: 20 pages, no figure

Kitchen-Sink Enlightenment: A Review of “Grace for Amateurs”

Excerpt: Here’s an honest admission: Several times while reading Lily Burana’s new book Grace for Amateurs: Field Notes on a Journey Back to Faith, I consulted the copyright page, confirming again that Grace for Amateurs was really published by Thomas Nelson, the notoriously evangelical (and, in my mind, notoriously traditional) press. After all, it wasn’t that long ago that Thomas Nelson asked another writer to remove the word “vagina” from her book, well aware that Christian readers would balk at language so closely associated with women and S-E-X. Would this same publisher be willing to support a memoir as edgy and progressive as Burana’s

The Arecibo Galaxy Environment Survey VII : A Dense Filament With Extremely Long HI Streams

We present completed observations of the NGC 7448 galaxy group and background volume as part of the blind neutral hydrogen Arecibo Galaxy Environment Survey (AGES). Our observations cover a region spanning 5x4 degrees, over a redshift range of approximately -2,000 < cz < 20,000 km/s. A total of 334 objects are detected, mostly in three overdensities at cz $\sim$7,500, cz $\sim$9,600 and cz $\sim$ 11,400 km/s. The galaxy density is extremely high (15 per square degree) and many ($\sim$24%) show signs of extended HI emission, including some features as much as 800 kpc in projected length. We describe the overall characteristics of this environment : kinematics, typical galaxy colours and mass to light ratios, and substructure. To aid in the cataloguing of this data set, we present a new FITS viewer (FRELLED : Fits Realtime Explorer of Low Latency in Every Dimension). This incorporates interactive source cataloguing tools which increase our source extraction speed by approximately a factor of 50.Comment: 15 pages, 13 figures, accepted for publication in MNRA