Gamma-ray Bursts, Classified Physically

From Galactic binary sources, to extragalactic magnetized neutron stars, to long-duration GRBs without associated supernovae, the types of sources we now believe capable of producing bursts of gamma-rays continues to grow apace. With this emergent diversity comes the recognition that the traditional (and newly formulated) high-energy observables used for identifying sub-classes does not provide an adequate one-to-one mapping to progenitors. The popular classification of some > 100 sec duration GRBs as ``short bursts'' is not only an unpalatable retronym and syntactically oxymoronic but highlights the difficultly of using what was once a purely phenomenological classification to encode our understanding of the physics that gives rise to the events. Here we propose a physically based classification scheme designed to coexist with the phenomenological system already in place and argue for its utility and necessity.Comment: 6 pages, 3 figures. Slightly expanded version of solicited paper to be published in the Proceedings of ''Gamma Ray Bursts 2007,'' Santa Fe, New Mexico, November 5-9. Edited by E. E. Fenimore, M. Galassi, D. Palme

Three-dimensional structure of I(to); Kv4.2-KChIP2 ion channels by electron microscopy at 21 Angstrom resolution.

Regulatory KChIP2 subunits assemble with pore-forming Kv4.2 subunits in 4:4 complexes to produce native voltage-gated potassium (Kv) channels like cardiac I(to) and neuronal I(A) subtypes. Here, negative stain electron microscopy (EM) and single particle averaging reveal KChIP2 to create a novel approximately 35 x 115 x 115 Angstrom, intracellular fenestrated rotunda: four peripheral columns that extend down from the membrane-embedded portion of the channel to enclose the Kv4.2 "hanging gondola" (a platform held beneath the transmembrane conduction pore by four internal columns). To reach the pore from the cytosol, ions traverse one of four external fenestrae to enter the rotundal vestibule and then cross one of four internal windows in the gondola

The Influence of High School Activity Portfolios on Risky Behaviors in Emerging Adulthood

Extracurricular participation in adolescence is often linked to the development of a prosocial identity and social relationships. Through these social psychological mechanisms, participation is thought to prevent risky behavior in adolescence and into emerging adulthood. This study examined the relationship between high school activity portfolios and risky behaviors (i.e. binge drinking, drug use, and law violation) among a college sample. Five activity portfolios were identified, including sports-focused, low involvement, highly engaged, and two combination portfolios. There were significant differences between portfolios on social psychological measures (e.g. prosocial beliefs and social responsibility), current extracurricular involvement, and risky behaviors. Regression models indicated that social psychological factors and current involvement partially mediated the association between portfolios and risky behaviors, but portfolio type retained direct effects. Portfolios associated with involvement across several activity domains were more protective for emerging adults, in part by shaping their beliefs, sense of social responsibility, and continuing involvement

FORTE antenna element and release mechanism design

The Fast On-Orbit Recording of Transient Events (FORTE) satellite being built by Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) has as its most prominent feature a large deployable (11 m by 5 m) log periodic antenna to monitor emissions from electrical storms on the Earth. This paper describes the antenna and the design for the long elements and explains the dynamics of their deployment and the damping system employed. It also describes the unique paraffin-actuated reusable tie-down and release mechanism employed in the system

Evidence of recent interkingdom horizontal gene transfer between bacteria and Candida parapsilosis

<p>Abstract</p> <p>Background</p> <p>To date very few incidences of interdomain gene transfer into fungi have been identified. Here, we used the emerging genome sequences of <it>Candida albicans </it>WO-1, <it>Candida tropicalis, Candida parapsilosis, Clavispora lusitaniae, Pichia guilliermondii</it>, and <it>Lodderomyces elongisporus </it>to identify recent interdomain HGT events. We refer to these as CTG species because they translate the CTG codon as serine rather than leucine, and share a recent common ancestor.</p> <p>Results</p> <p>Phylogenetic and syntenic information infer that two <it>C. parapsilosis </it>genes originate from bacterial sources. One encodes a putative proline racemase (PR). Phylogenetic analysis also infers that there were independent transfers of bacterial PR enzymes into members of the Pezizomycotina, and protists. The second HGT gene in <it>C. parapsilosis </it>belongs to the phenazine F (PhzF) superfamily. Most CTG species also contain a fungal PhzF homolog. Our phylogeny suggests that the CTG homolog originated from an ancient HGT event, from a member of the proteobacteria. An analysis of synteny suggests that <it>C. parapsilosis </it>has lost the endogenous fungal form of PhzF, and subsequently reacquired it from a proteobacterial source. There is evidence that <it>Schizosaccharomyces pombe </it>and Basidiomycotina also obtained a PhzF homolog through HGT.</p> <p>Conclusion</p> <p>Our search revealed two instances of well-supported HGT from bacteria into the CTG clade, both specific to <it>C. parapsilosis</it>. Therefore, while recent interkingdom gene transfer has taken place in the CTG lineage, its occurrence is rare. However, our analysis will not detect ancient gene transfers, and we may have underestimated the global extent of HGT into CTG species.</p

Impact of the Academic-Social Context on American Indian/Alaska Native Students’ Academic Performance

Impact of the Academic-Social Context on American Indian/Alaska Native Students’ Academic Performanc

Cutting to Order in the Rough Mill: A Sampling Approach

A cutting order is a list of dimension parts along with demanded quantities. The cutting-order problem is to minimize the total cost of filling a cutting order from a given lumber supply. Similar cutting-order problems arise in many industrial situations outside of forest products. This paper adapts an earlier, linear programming approach that was developed for uniform, defect-free stock materials. The adaptation presented here allows the method to handle nonuniform stock material (e.g., lumber) that contains defects that are not known in advance of cutting. The main differences are the use of a random sample to construct the linear program and the use of prices rather than cutting patterns to specify a solution. The primary result of this research is that the expected cost of filling an order under the proposed method is approximately equal to the minimum possible expected cost for sufficiently large order and sample sizes. A secondary result is a lower bound on the minimum possible expected cost. Computer simulations suggest that the proposed method is capable of attaining nearly minimal expected costs in moderately large orders