The πN→e+e−N\pi N \to e^+e^- N reaction close to the vector meson production threshold

The $\pi^-p \to e^+e^- n$ and $\pi^+n \to e^+e^- p$ reaction cross sections are calculated below and in the vicinity of the vector meson ($\rho^0$, $\omega$) production threshold. These processes are largely responsible for the emission of $e^+e^-$ pairs in pion-nucleus reactions and contribute to the dilepton spectra observed in relativistic heavy ion collisions. They are dominated by the decay of low-lying baryon resonances into vector meson-nucleon channels. The vector mesons materialize subsequently into $e^+e^-$ pairs. Using $\pi N\to \rho^0 N$ and $\pi N \to \omega N$ amplitudes calculated in the center of mass energy interval $1.4<\sqrt s <1.8$ GeV, we compute the $\pi^-p \to e^+e^- n$ and $\pi^+n \to e^+e^- p$ reaction cross sections in these kinematics. Below the vector meson production threshold, the $\rho^0 - \omega$ interference in the $e^+e^-$ channel appears largely destructive for the $\pi^-p \to e^+e^- n$ cross section and constructive for the $\pi^+n \to e^+e^- p$ cross section. The pion beam and the HADES detector at GSI offer a unique possibility to measure these effects. Such data would provide strong constraints on the coupling of vector meson-nucleon channels to low-lying baryon resonances.Comment: Talk given at the Budapest'02 Workshop on Quark and Hadron Dynamics, Budapest (Hungary), March 3rd-7th, 200

Status of the Beryllium Industry in the United States of America

THE first industrial production of metal beryllium in the United States dates back to 1939, when The Brush Beryllium Co. established a small plant. The earlier activities connected with beryllium industry were however confined only to the sales of beryllium nitr- ate and beryllium oxide in minor quantities. In the 1930's, alloys of beryllium copper became the industry's main product and have so remained almost up to the present time. Sales of beryllium metal started to grow slowly in the early 1940's. The increasing demand for the metal, which in the following ten years fluctuated greatly, has now become more steady and has, particul- arly during the last 3-4 years, grown so rapidly that the dollar value of sales of beryllium metal in primary or fabricated form now is exceeding the dollar sales volume of beryllium copper alloys and fabricated alloy products

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Smoking and the risk of hospitalization for symptomatic diverticular disease: a population-based cohort study from Sweden

BACKGROUND: Current studies reporting on the risk of smoking and development of symptomatic diverticular disease have reported conflicting results. OBJECTIVE: The aim of this study was to investigate the association between smoking and symptomatic diverticular disease. DESIGN: This is a cohort study. SETTINGS: : Information was derived from the Swedish Construction Workers Cohort 1971-1993. PATIENTS: Patients were selected from construction workers in Sweden. MAIN OUTCOME MEASURES: The primary outcome measured was the development of symptomatic diverticular disease and complicated diverticular disease (abscess and perforation) as identified in the Swedish Hospital Discharge Register. Adjusted relative risks of symptomatic diverticular disease according to smoking status were estimated by using negative binomial regression analysis. RESULTS: In total, the study included 232,685 men and 14,592 women. During follow-up, 3891 men and 318 women had a diagnosis of later symptomatic diverticular disease. In men, heavy smokers (>/=15 cigarettes a day) had a 1.6-fold increased risk of developing symptomatic diverticular disease compared with nonsmokers (adjusted relative risk, 1.56; 95% CI, 1.42-1.72). There was evidence of a dose-response relationship, because moderate and ex-smokers had a 1.4- and 1.2-fold increased risk compared with nonsmokers (adjusted relative risk, 1.39; 95% CI, 1.27-1.52 and adjusted relative risk, 1.14; 95% CI, 1.04-1.27). These relationships were similar in women, but the risk estimates were less precise owing to smaller numbers. Male ever-smokers had a 2.7-fold increased risk of developing complicated diverticular disease (perforation/abscess) compared with nonsmokers (adjusted relative risks, 2.73; 95% CI, 1.69-4.41). LIMITATIONS: We were unable to account for other confounding variables such as comorbidity, prescription medication, or lifestyle factors. CONCLUSIONS: Smoking is associated with symptomatic diverticular disease in both men and women and with an increased risk of developing complicated diverticular disease

Structural Raman Enhancement in Graphite Nano-Discs

Raman scattering in disc-shaped graphite nanostructures, etched out of bulk HOPG, are investigated using an excitation wavelength of 532 nm at different laser power. The G-band is fitted using two Lorentzian functions, G(L) and G(H). The difference of Raman shift between the two Lorentzian functions increase with laser power as a consequence of selective absorption and heating of the discs. Further, the G-band from the nanostructured HOPG reveal a Raman enhancement (R-E) of similar to 2.2 and similar to 1.5 for the components associated with the discs (G(L)) and the supporting substrate (G(H)), respectively. The quantitative agreement between the experimental results and performed finite difference time domain calculations make possible to conclude that electromagnetic energy penetrates considerably into the discs from the circular periphery probably due to multiple scattering. In addition, the dependence of R-E of the G(L) component on the laser power is attributed to a temperature dependent electron-phonon coupling

Visualisation of ectomycorrhizal rhizomorph structure using laser scanning confocal microscopy

A method for the observation of the three-dimensional structure of intact ectomycorrhizal rhizomorphs is described. The method is based on a combination of clearing the material with KOH followed by staining with congo red and subsequent imaging under a laser scanning confocal microscope (LSCM). The images obtained are of a much higher three-dimensional resolution than those obtained previously by use of conventional light microscopical techniques. The structure of highly differentiated and undifferentiated rhizomorphs is described. Applications of the method are briefly discussed

Charge fluctuations in chiral models and the QCD phase transition

We consider the Polyakov loop-extended two flavor chiral quark--meson model and discuss critical phenomena related with the spontaneous breaking of the chiral symmetry. The model is explored beyond the mean-field approximation in the framework of the functional renormalisation group. We discuss properties of the net-quark number density fluctuations as well as their higher cumulants. We show that with the increasing net-quark number density, the higher order cumulants exhibit a strong sensitivity to the chiral crossover transition. We discuss their role as probes of the chiral phase transition in heavy-ion collisions at RHIC and LHC.Comment: 4 pages, 3 figures, to appear in the proceedings of Quark Matter 2011, 23-28 May 2011, Annecy, Franc

Novel roles for JNK1 in metabolism

Activation of stress-kinase signaling has recently been recognized as an important pathophysiological mechanism in the development of diet-induced obesity, type 2 diabetes mellitus and other aging-related pathologies. Here, c-Jun N-terminal Kinase (JNK) 1 knockout mice have been shown to exhibit protection from diet-induced obesity, glucose intolerance, and insulin resistance. Nonetheless, the tissue-specific role of JNK1-activation in the development of the metabolic syndrome has been poorly defined so far. Recently, it was demonstrated that JNK1 signaling plays a crucial role in the central nervous system (CNS) and in the pituitary to control systemic glucose and lipid metabolism partially through regulation of hormones involved in growth and energy expenditure

On the Use of Blanketed Atmospheres as Boundary Conditions for Stellar Evolutionary Models

Stellar models have been computed for stars having [Fe/H] = 0.0 and -2.0 to determine the effects of using boundary conditions derived from the latest MARCS model atmospheres. The latter were fitted to the interior models at both the photosphere and at tau = 100, and at least for the 0.8-1.0 solar mass stars considered here, the resultant evolutionary tracks were found to be nearly independent of the chosen fitting point. Particular care was taken to treat the entire star as consistently as possible; i.e., both the interior and atmosphere codes assumed the same abundances and the same treatment of convection. Tracks were also computed using either the classical gray T(tau,T_eff) relation or that derived by Krishna Swamy (1966) to derive the boundary pressure. The latter predict warmer giant branches (by ~150 K) at solar abundances than those based on gray or MARCS atmospheres, which happens to be in good agreement with the inferred temperatures of giants in the open cluster M67 from the latest (V-K)-T_eff relations. Most of the calculations assumed Z=0.0125 (Asplund et al.), though a few models were computed for Z=0.0165 (Grevesse & Sauval) to determine the dependence of the tracks on Z_\odot. Grids of "scaled solar, differentially corrected" (SDC) atmospheres were also computed to try to improve upon theoretical MARCS models. When they were used as boundary conditions, the resultant tracks agreed very well with those based on a standard scaled-solar (e.g., Krishna Swamy) T(tau,T_eff) relation, independently of the assumed metal abundance. Fits of isochrones to the C-M diagram of the [Fe/H] = -2 globular cluster M68 were examined, as was the possibility that the mixing-length parameter varies with stellar parameters.Comment: 54 pages, including 20 figures and 3 tables; accepted (July 2007) for publication in the Astrophysical Journa

Van der Waals effect in weak adsorption affecting trends in adsorption, reactivity, and the view of substrate nobility

The ubiquitous van der Waals (vdW) force, particularly discernible in weak adsorption, is studied on noble and transition metals. In calculations with the vdW density functional (DF) [ M. Dion et al., Phys. Rev. Lett. 92, 246401 (2004)], the atomic structure near the adsorption site is systematically varied, including dense fcc(111) surface, adatom, pyramid, and step defects. In weak adsorption the vdW force (i) is shown necessary to account for, (ii) is sizable, (iii) has a strong spatial variation, relevant for adsorption on surface defects, (iv) changes reaction rules, and (v) changes adsorption trends in agreement with experimental data. Traditional physisorption theory is also given support and interpretation