Gamma-Ray Bursts Observed with the Spectrometer SPI Onboard INTEGRAL

The spectrometer SPI is one of the main detectors of ESA's INTEGRAL mission. The instrument offers two interesting and valuable capabilities for the detection of the prompt emission of Gamma-ray bursts. Within a field of view of 16 degrees, SPI is able to localize Gamma-ray bursts with an accuracy of 10 arcmin. The large anticoincidence shield, ACS, consisting of 512 kg of BGO crystals, detects Gamma-ray bursts quasi omnidirectionally above ~70 keV. Burst alerts from SPI/ACS are distributed to the interested community via the INTEGRAL Burst Alert System. The ACS data have been implemented into the 3rd Interplanetary Network and have proven valuable for the localization of bursts using the triangulation method. During the first 8 months of the mission approximately one Gamma-ray burst per month was localized within the field of fiew of SPI and 145 Gamma-ray burst candidates were detected by the ACS from which 40 % have been confirmed by other instruments.Comment: 4 pages, 2 figures, to appear in the Proceedings of the Conference "30 Years of GRB Discovery", Santa Fe, New Mexico, USA, September 8-12, 200

Critical Evaluation and Compilation of Viscosity and Diffusivity Data Semiannual Status Report No. 1, Jul. 1 - Dec. 31, 1965

Compilation and evaluation of diffusivity and viscosity data on gas and liquid turbulent flow system

The Bis(ferrocenyl)phosphenium Ion Revisited

The bis(ferrocenyl)phosphenium ion, [Fc2P]+, reported by Cowley et al. (J. Am. Chem. Soc. 1981, 103, 714–715), was the only claimed donor‐free divalent phosphenium ion. Our examination of the molecular and electronic structure reveals that [Fc2P]+ possesses significant intramolecular Fe⋅⋅⋅P contacts, which are predominantly electrostatic and moderate the Lewis acidity. Nonetheless, [Fc2P]+ undergoes complex formation with the Lewis bases PPh3 and IPr to give the donor–acceptor complexes [Fc2P(PPh3)]+ and [Fc2P(IPr)]+ (IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazole‐2‐ylidene)

Evidence for crossed Andreev reflection in superconductor-ferromagnet hybrid structures

We have measured the non-local resistance of aluminum-iron spin-valve structures fabricated by e-beam lithography and shadow evaporation. The sample geometry consists of an aluminum bar with two or more ferromagnetic wires forming point contacts to the aluminum at varying distances from each other. In the normal state of aluminum, we observe a spin-valve signal which allows us to control the relative orientation of the magnetizations of the ferromagnetic contacts. In the superconducting state, at low temperatures and excitation voltages well below the gap, we observe a spin-dependent non-local resistance which decays on a smaller length scale than the normal-state spin-valve signal. The sign, magnitude and decay length of this signal is consistent with predictions made for crossed Andreev reflection (CAR).Comment: RevTeX, 4 page

A comparison of resistance patterns on swine farms using or excluding antimicrobial products

The effects of farm use or exclusion of antibiotics on antibiotic resistance patterns of bacteria were compared using fecal samples from live swine. Four farms that used antibiotics and three farms that excluded antibiotics from production were selected and from each farm, 6 pigs from each of 4 weight groups (4.5, 23, 45, and 109 kg) and 5 sows were randomly selected for collection of fecal samples. E. coli, O157:H7 E. coli, and Salmonella spp. were isolated from fecal samples and tested for sensitivity to gentamicin, sulfamethazine, oxytetracycline, ceftiofur, and ampicillin using a standardized minimum inhibitory concentration (MIC) analysis. Resistance patterns were markedly different between farm types in E. coli, and moderately so in Salmonella. In both cases, isolates from farms that excluded antibiotics had lower (P \u3c 0.05) MICs. The number of resistant isolates and those that demonstrated multiple resistance patterns was greater (P \u3c 0.05) on farms that used antibiotics. E. coli from farms that excluded antibiotics had significantly lower (P \u3c 0.001) MICs for gentamicin, sulfamethazine, oxytetracycline, and ampicillin and lower (P \u3c 0.10) MICs for ceftiofur. Farm type differences were most evident for isolates from younger pigs for gentamicin, ceftiofur, and ampicillin but were also noted among all pig groups for sulfamethazine and oxytetracycline. In Salmonella, the MICs were higher from farms that used antibiotics particularly for oxytetracycline and ceftiofur (P \u3c 0.001). O157:H7 E. coli were isolated from 2 farms, both of which used antibiotics in production, thus a relevant analysis on that bacterium was not possible. In total, these data indicate that exclusion of antibiotics in swine production decreases antibiotic resistance in E. coli, and to a lesser extent resistance in salmonellae

Nonexponential 1H Spin-Lattice Relaxation and Methyl Group Rotation in Molecular Solids

We report a quantitative measure of the nonexponential 1H spin-lattice relaxation resulting from methyl group (CH3) rotation in six polycrystalline van der Waals solids. We briefly review the subject in general to put the report in context. We then summarize several significant issues to consider when reporting 1H or 19F spin-lattice relaxation measurements when the relaxation is resulting from the rotation of a CH3 or CF3 group in a molecular solid