Ultrahard spectra of PeV neutrinos from supernovae in compact star clusters

Starburst regions with multiple powerful winds of young massive stars and supernova remnants are favorable sites for high-energy cosmic ray acceleration. A supernova shock colliding with a fast wind from a compact cluster of young stars allows the acceleration of protons to energies well above the standard limits of diffusive shock acceleration in an isolated SN. The proton spectrum in such a wind-supernova PeV accelerator is hard with a large flux in the high-energy-end of the spectrum producing copious gamma-rays and neutrinos in inelastic nuclear collisions. We argue that SN shocks in the Westerlund 1 cluster in the Milky Way may accelerate protons to about 40 PeV. Once accelerated, these CRs will diffuse into surrounding dense clouds and produce neutrinos with fluxes sufficient to explain a fraction of the events detected by IceCube Observatory from the inner Galaxy.Comment: 10 pages, 7 figures, MNRAS v.453, p.113-121, 201

Methods for structural design at elevated temperatures

A procedure which can be used to design elevated temperature structures is discussed. The desired goal is to have the same confidence in the structural integrity at elevated temperature as the factor of safety gives on mechanical loads at room temperature. Methods of design and analysis for creep, creep rupture, and creep buckling are presented. Example problems are included to illustrate the analytical methods. Creep data for some common structural materials are presented. Appendix B is description, user's manual, and listing for the creep analysis program. The program predicts time to a given creep or to creep rupture for a material subjected to a specified stress-temperature-time spectrum. Fatigue at elevated temperature is discussed. Methods of analysis for high stress-low cycle fatigue, fatigue below the creep range, and fatigue in the creep range are included. The interaction of thermal fatigue and mechanical loads is considered, and a detailed approach to fatigue analysis is given for structures operating below the creep range

Colorado’s legalization of medicinal marijuana is linked to a rise in marijuana-related arrests in some parts of Nebraska.

Marijuana has now been legal in Colorado for medicinal use for more than 15 years. Over this time, authorities in neighboring Nebraska (where the drug remains illegal) have become concerned about the potential spillover of marijuana into their state’s counties. In new research, Jared M. Ellison and Ryan E. Spohn find that Nebraska’s border counties, and to a lesser extent those along the I-80 highway corridor, have experienced an upward trend in marijuana-related arrests and jail admissions. In light of these findings, they write, both states and the federal government may need to rethink their marijuana laws and make decisions about penalties and potential legalization

Borders Up in Smoke: Marijuana Enforcement in Nebraska After Colorado’s Legalization of Medicinal Marijuana

With the passage of Amendments 20 (2000) and 64 (2012), Colorado legalized the medicinal and recreational use of marijuana. Nebraskan law enforcement in border counties subsequently reported increases in arrests and reductions in jail space. In response, the Nebraska state legislature passed LR-520 to study the potential increased costs incurred by criminal justice agencies in border counties. To investigate this situation, we compare trends in drug arrests and jail occupancy across three areas: border counties, those that contain Interstate 80 (I-80) as a major transportation route, and the remaining counties in the state of Nebraska from 2000 through 2013. We found that border counties, but not necessarily those along the I-80 corridor, experienced significant growth in marijuana-related arrests and jail admissions after the expansion of the medical marijuana program in Colorado. Implications for research and policy are discussed

Colorado’s legalization of medicinal marijuana: The effects on Nebraska’s law enforcement and local jail system

With the passage of Amendment 20 in 2000 and Amendment 64 in 2012, Colorado legalized the medicinal and recreational use of marijuana. Subsequently, Nebraskan law enforcement agencies in border counties have reported increases in arrests and jail admissions for marijuana-related offenses. In response, the Nebraska Legislature passed Legislative Resolution 520 to study potential increased costs incurred by criminal justice agencies in border counties. In order to better understand how Colorado drug policy may have affected counties along the border, we compared trends in marijuana-related criminal justice activity among county agencies following the enactment of both Amendments. Border county arrests, jail admissions, and associated costs of incarceration were compared to two other county groups, those that contain Interstate I-80 as a major transportation route, and a “control group” comprised of the remaining counties in the state of Nebraska from 2000 through 2013. This analysis approximates a “natural experiment” based on the assumption that Nebraska counties that border Colorado will experience the largest impact from the legal changes in Colorado. Because Interstate 80 is the major east/west thoroughfare in Nebraska linking Colorado to the east, we assume the counties along the I-80 corridor will experience an impact that is less than that of border counties, but higher than control counties. Finally, we assume that “control counties” that are neither border counties, nor I-80 corridor counties, will be affected the least since 2000

Nonlinear Diffusive Shock Acceleration with Magnetic Field Amplification

We introduce a Monte Carlo model of nonlinear diffusive shock acceleration allowing for the generation of large-amplitude magnetic turbulence. The model is the first to include strong wave generation, efficient particle acceleration to relativistic energies in nonrelativistic shocks, and thermal particle injection in an internally self-consistent manner. We find that the upstream magnetic field can be amplified by large factors and show that this amplification depends strongly on the ambient Alfven Mach number. We also show that in the nonlinear model large increases in the magnetic field do not necessarily translate into a large increase in the maximum particle momentum a particular shock can produce, a consequence of high momentum particles diffusing in the shock precursor where the large amplified field converges to the low ambient value. To deal with the field growth rate in the regime of strong fluctuations, we extend to strong turbulence a parameterization that is consistent with the resonant quasi-linear growth rate in the weak turbulence limit. We believe our parameterization spans the maximum and minimum range of the fluctuation growth and, within these limits, we show that the nonlinear shock structure, acceleration efficiency, and thermal particle injection rates depend strongly on the yet to be determined details of wave growth in strongly turbulent fields. The most direct application of our results will be to estimate magnetic fields amplified by strong cosmic-ray modified shocks in supernova remnants.Comment: Accepted in ApJ July 2006, typos corrected in this versio

The host galaxy of GRB010222: The strongest damped Lyman-alpha system known

Analysis of the absorption lines in the afterglow spectrum of the gamma-ray burst GRB010222 indicates that its host galaxy (at a redshift of z=1.476) is the strongest damped Lyman-alpha (DLA) system known, having a very low metallicity and modest dust content. This conclusion is based on the detection of the red wing of Lyman-alpha plus a comparison of the equivalent widths of ultraviolet Mg I, Mg II, and Fe II lines with those in other DLAs. The column density of H I, deduced from a fit to the wing of Lyman-alpha, is (5 +/- 2) 10^22 cm^-2. The ratio of the column densities of Zn and Cr lines suggests that the dust content in our line of sight through the galaxy is low. This could be due to either dust destruction by the ultraviolet emission of the afterglow or to an initial dust composition different to that of the diffuse interstellar material, or a combination of both.Comment: Submitted to MNRAS 12 page