Effect of exotic S=+1 resonances on KL0pK^0_L p scattering data

We consider the effect of an exotic S=+1 $\Theta^+$ resonance on the scattering of neutral kaons off protons. Explicit results are presented for the $K^0_L p$ total cross sections.Comment: 2 pages, 3 figure

Large harmonic softening of the phonon density of states of uranium

Phonon density-of-states curves were obtained from inelastic neutron scattering spectra from the three crystalline phases of uranium at temperatures from 50 to 1213 K. The alpha -phase showed an unusually large thermal softening of phonon frequencies. Analysis of the vibrational power spectrum showed that this phonon softening originates with the softening of a harmonic solid, as opposed to vibrations in anharmonic potentials. It follows that thermal excitations of electronic states are more significant thermodynamically than are the classical volume effects. For the alpha-beta and beta-gamma phase transitions, vibrational and electronic entropies were comparable

Gentamicin pharmacokinetics during slow daily home hemodialysis

Gentamicin pharmacokinetics during slow daily home hemodialysis.BackgroundGentamicin is commonly used in hemodialysis patients. Gentamicin pharmacokinetics during traditional hemodialysis have been described. Slow daily home (SDH) hemodialysis (7 to 9 hours a day/6 days a week) use is increasing due to benefits observed with increased hemodialysis. We determined gentamicin pharmacokinetics for SDH hemodialysis patients.MethodsEight patients (four male and four female) received a single intravenous dose of 0.6 mg/kg gentamicin post-hemodialysis. Blood samples were collected at 5, 10, 15, 30, and 60 minutes after dose. The next day patients underwent a typical SDH hemodialysis (high-flux F50NR dialyzer) session. Blood samples were taken at 0, 5, 15, 60, 120, 240, 360, 480 minutes during and 15, 30 and 60 minutes post-hemodialysis. Baseline and 24-hour urine samples were collected. Pharmacokinetic parameters were calculated assuming a one-compartment model.ResultsPatients were 42.5 ± 13.1 years old (mean ± SD). Inter-, intra-, and post-hemodialysis collection periods were 17.0 ± 2.1 hours, 8.1 ± 0.4 hours, and 1.1 ± 0.1 hours, respectively. Intra-, and interdialytic gentamicin half-lives were different (intradialytic, 3.7 ± 0.8 hours; interdialytic, 20.4 ± 4.7 hours; P < 0.0001). Hemodialysis clearance accounted for 70.5% gentamicin total clearance. Renal clearance correlated with glomerular filtration rate (GFR) (renal clearance = 1.2 GFR; r2 = 0.98; P < 0.001). Mean peak and trough of hemodialysis concentrations were 1.8 ± 0.6 μg/mL and 0.5 ± 0.2 μg/mL, respectively. Post-hemodialysis rebound was 3.1 ± 8.8% at 1 hour.ConclusionPharmacokinetic model predicts 2.0 to 2.5 mg/kg dose gentamicin post-hemodialysis would provide peak (1 hour post-dose) and trough (end of SDH hemodialysis session) concentrations of 6.0 to 7.5 μg/mL and 0.7 to 0.8 μg/mL, respectively. This would provide adequate coverage for most gram-negative organisms in SDH hemodialysis patients

The energies and residues of the nucleon resonances N(1535) and N(1650)

We extract pole positions for the N(1535) and N(1650) resonances using two different models. The positions are determined from fits to different subsets of the existing $\pi N\to\pi N$, $\pi N\to\eta N$ and $\gamma p\to\eta p$ data and found to be 1515(10)--i85(15)MeV and 1660(10)--i65(10)MeV, when the data is described in terms of two poles. Sensitivity to the choice of fitted data is explored. The corresponding $\pi \pi$ and $\eta \eta$ residues of these poles are also extracted.Comment: 9 page

Filaments as Possible Signatures of Magnetic Field Structure in Planetary Nebulae

We draw attention to the extreme filamentary structures seen in high-resolution optical images of certain planetary nebulae. We determine the physical properties of the filaments in the nebulae IC 418, NGC 3132, and NGC 6537, and based on their large length-to-width ratios, longitudinal coherence, and morphology, we suggest that they may be signatures of the underlying magnetic field. The fields needed for the coherence of the filaments are probably consistent with those measured in the precursor circumstellar envelopes. The filaments suggest that magnetic fields in planetary nebulae may have a localized and thread-like geometry.Comment: 26 pages with 7 figures. To be published in PASP. For full resolution images see http://physics.nyu.edu/~pjh

The benefits of organic farming for biodiversity

Previous studies suggest widespread positive responses of biodiversity to organic farming. Many of these studies, however, have been small-scale. This project tested the generality of habitat and biodiversity differences between matched pairs of organic and non-organic farms containing cereal crops in lowland England on a large-scale across a range of taxa including plants, insects, birds and bats. The extent of both cropped and un-cropped habitats together with their composition and management on a range of scales were also compared. Organic farms was likely to favour higher levels of biodiversity and indeed organic farms tended to support higher numbers of species and overall abundance across most taxa. However, the magnitude of the response differed strikingly; plants showed stronger and more consistent responses than other taxa. Some, but not all, differences in biodiversity between systems appear to be a consequence of differences in habitat quantity

Microstructural strain energy of α-uranium determined by calorimetry and neutron diffractometry

The microstructural contribution to the heat capacity of α-uranium was determined by measuring the heat-capacity difference between polycrystalline and single-crystal samples from 77 to 320 K. When cooled to 77 K and then heated to about 280 K, the uranium microstructure released (3±1) J/mol of strain energy. On further heating to 300 K, the microstructure absorbed energy as it began to redevelop microstrains. Anisotropic strain-broadening parameters were extracted from neutron-diffraction measurements on polycrystals. Combining the strain-broadening parameters with anisotropic elastic constants from the literature, the microstructural strain energy is predicted in the two limiting cases of statistically isotropic stress and statistically isotropic strain. The result calculated in the limit of statistically isotropic stress was (3.7±0.5) J/mol K at 77 K and (1±0.5) J/mol at room temperature. In the limit of statistically isotropic strain, the values were (7.8±0.5) J/mol K at 77 K and (4.5±0.5) J/mol at room temperature. In both cases the changes in the microstructural strain energy showed good agreement with the calorimetry