The Effect of Multiple Cooling Channels on the Formation of Dark Compact Objects

A dissipative dark sector can result in the formation of compact objects with masses comparable to stars and planets. In this work, we investigate the formation of such compact objects from a subdominant inelastic dark matter model, and study the resulting distributions of these objects. In particular, we consider cooling from dark Bremsstrahlung and a rapid decay process that occurs after inelastic upscattering. Inelastic transitions introduce an additional radiative processes which can impact the formation of compact objects via multiple cooling channels. We find that having multiple cooling processes changes the mass and abundance of compact objects formed, as compared to a scenario with only one cooling channel. The resulting distribution of these astrophysical compact objects and their properties can be used to further constrain and differentiate between dark sectors.Comment: 20 pages, 4 figure

The Maluridae: Inferring Avian Biology and Evolutionary History from DNA Sequences

The Australo-Papuan fairy-wrens, emu-wrens and grasswrens comprise the passerine family Maluridae. They have long been known for their spectacular plumages, remarkable behavioural ecology and intriguing biogeography. The family has provided an ideal model with which to explore how phylogenetic and phylogeographic analyses of DNA-sequence data can inform understanding of evolutionary history and present-day biology. We review what has been learned of the phylogeny of the group and the phylogeographic history of individual species. We conclude that there is now a strong framework within which to pursue the remaining species-level taxonomic issues, and to extend ecological and behavioural studies into a new era of more detailed genetic questions such as the role of gene–environment interactions in adaptation. We highlight some remaining examples of such questions and discuss how they might be addressed.Organismic and Evolutionary Biolog

Contributors to the March Issue/Notes

Notes by Robert E. Richardson, Bernard F. Grainey, Leo L. Linck, Joseph J. Miller, Jr., James E. Diver, William B. Mooney, John M. Speca, Timothy M. Green, and Daniel D. Dahill

Dust Temperatures in the Infrared Space Observatory Atlas of Bright Spiral Galaxies

We examine far-infrared and submillimeter spectral energy distributions for galaxies in the Infrared Space Observatory Atlas of Bright Spiral Galaxies. For the 71 galaxies where we had complete 60-180 micron data, we fit blackbodies with lambda^-1 emissivities and average temperatures of 31 K or lambda^-2 emissivities and average temperatures of 22 K. Except for high temperatures determined in some early-type galaxies, the temperatures show no dependence on any galaxy characteristic. For the 60-850 micron range in eight galaxies, we fit blackbodies with lambda^-1, lambda-2, and lambda^-beta (with beta variable) emissivities to the data. The best results were with the lambda^-beta emissivities, where the temperatures were ~30 K and the emissivity coefficient beta ranged from 0.9 to 1.9. These results produced gas to dust ratios that ranged from 150 to 580, which were consistent with the ratio for the Milky Way and which exhibited relatively little dispersion compared to fits with fixed emissivities.Comment: AJ, 2003, in pres

Towards Space-like Photometric Precision from the Ground with Beam-Shaping Diffusers

We demonstrate a path to hitherto unachievable differential photometric precisions from the ground, both in the optical and near-infrared (NIR), using custom-fabricated beam-shaping diffusers produced using specialized nanofabrication techniques. Such diffusers mold the focal plane image of a star into a broad and stable top-hat shape, minimizing photometric errors due to non-uniform pixel response, atmospheric seeing effects, imperfect guiding, and telescope-induced variable aberrations seen in defocusing. This PSF reshaping significantly increases the achievable dynamic range of our observations, increasing our observing efficiency and thus better averages over scintillation. Diffusers work in both collimated and converging beams. We present diffuser-assisted optical observations demonstrating $62^{+26}_{-16}$ppm precision in 30 minute bins on a nearby bright star 16-Cygni A (V=5.95) using the ARC 3.5m telescope---within a factor of $\sim$2 of Kepler's photometric precision on the same star. We also show a transit of WASP-85-Ab (V=11.2) and TRES-3b (V=12.4), where the residuals bin down to $180^{+66}_{-41}$ppm in 30 minute bins for WASP-85-Ab---a factor of $\sim$4 of the precision achieved by the K2 mission on this target---and to 101ppm for TRES-3b. In the NIR, where diffusers may provide even more significant improvements over the current state of the art, our preliminary tests have demonstrated $137^{+64}_{-36}$ppm precision for a $K_S =10.8$ star on the 200" Hale Telescope. These photometric precisions match or surpass the expected photometric precisions of TESS for the same magnitude range. This technology is inexpensive, scalable, easily adaptable, and can have an important and immediate impact on the observations of transits and secondary eclipses of exoplanets.Comment: Accepted for publication in ApJ. 30 pages, 20 figure

Navigating the structural landscape of de Novo α-helical bundles

The association of amphipathic α helices in water leads to α-helical-bundle protein structures. However, the driving force for thisthe hydrophobic effectis not specific and does not define the number or the orientation of helices in the associated state. Rather, this is achieved through deeper sequence-to-structure relationships, which are increasingly being discerned. For example, for one structurally extreme but nevertheless ubiquitous class of bundlethe α-helical coiled coilsrelationships have been established that discriminate between all-parallel dimers, trimers, and tetramers. Association states above this are known, as are antiparallel and mixed arrangements of the helices. However, these alternative states are less well understood. Here, we describe a synthetic-peptide system that switches between parallel hexamers and various up–down–up–down tetramers in response to single-amino-acid changes and solution conditions. The main accessible states of each peptide variant are characterized fully in solution and, in most cases, to high resolution with X-ray crystal structures. Analysis and inspection of these structures helps rationalize the different states formed. This navigation of the structural landscape of α-helical coiled coils above the dimers and trimers that dominate in nature has allowed us to design rationally a well-defined and hyperstable antiparallel coiled-coil tetramer (apCC-Tet). This robust de novo protein provides another scaffold for further structural and functional designs in protein engineering and synthetic biology

Fall 1956

Greetings from the Club President (page 2) Winter School and Turf Conference Cancelled for 1957 (2) Value of Turf Clippings (3) Dedication--Minor J. Markuson (4) Interrelations between Design, Construction and Maintenance (6) Golf Course Design (6) Relationship of Golf Course Design to Maintenance Costs (9) Influence of Construction upon maintenance (12) Snow Blue - Snow White (14) Post Emergence Control of Crabgrass (15) Third Generation in Greenkeeping (16) Hand Greens Mowers (17) Equipment (18) Pelham Country Club vs New England Thruway (18) Should Junior Memberships be Allowed (19) Meet the Staff (20) Turf Club News (23) Chairman-superintendent Relationship: Quote by Dickinson (24) Letter To Dean Sieling from New England Golf Course Superintendent\u27s Association (24) Associate Members of Stockbridge Turf Management Club (25) Membership Application Form for Turf Management Club (26

Psychometric validation of the BDI-II among HIV-positive CHARTER study participants.

Rates of depression are high among individuals living with HIV. Accurate assessment of depressive symptoms among this population is important for ensuring proper diagnosis and treatment. The Beck Depression Inventory-II (BDI-II) is a widely used measure for assessing depression, however its psychometric properties have not yet been investigated for use with HIV-positive populations in the U.S. The current study was the first to assess the psychometric properties of the BDI-II among a large cohort of HIV-positive participants sampled at multiple sites across the U.S. as part of the CNS HIV Antiretroviral Therapy Effects Research (CHARTER) study. The BDI-II test scores showed good internal consistency (α = 0.93) and adequate test-retest reliability (ICC = 0.83) over a 6-month period. Using a ‘gold standard’ of major depressive disorder determined by the Composite International Diagnostic Interview (CIDI), sensitivity and specificity were maximized at a total cut-off score of 17 and a Receiver Operating Characteristic (ROC) analysis confirmed that the BDI-II is an adequate diagnostic measure for the sample (AUC = 0.83). The sensitivity and specificity of each score are provided graphically. Confirmatory factor analyses confirmed the best fit for a 3-factor model over 1-factor and 2-factor models and models with a higher-order factor included. The results suggest that the BDI-II is an adequate measure for assessing depressive symptoms among U.S. HIV-positive patients. Cut-off scores should be adjusted to enhance sensitivity or specificity as needed and the measure can be differentiated into cognitive, affective, and somatic depressive symptoms