SU(3) Breaking Effects in Hyperon Semi-Leptonic Decays and the extraction of F and D

The analysis of hyperon semi-leptonic decay data is re-examined in the light of a recent suggestion that SU(3) symmetry breaking effects may be taken into account by applying a correction to the $F/D$ ratio obtained via naive linear extrapolation in the hyperon masses. Comparison is made with the physically better motivated approach of applying so-called centre-of-mass corrections. This study (including all available data) reveals certain short-comings of the former of the above treatments, highlights some interesting aspects of this type of analysis and attempts to pinpoint the decay data that might usefully be improved. A tantalising result of the SU(3) breaking analysis performed here is that the magnitude of recoil correction required by the data corresponds closely to that required for the standard explanation of the reduction of \gA from its SU(6) value of 5/3. We also comment on other recent suggestions for taking into account the effects of SU(3) breaking. Finally a few remarks are made on the relevance for predicting the flavour non-singlet contribution to the proton $g_1$ and the Ellis-Jaffe sum rule.Comment: 12 pages, latex, no figures. Removed extended ascii set characters in the source file that were being corrupted by some mailer

Temperature coefficients of crystalline-quartz elastic constants over the cryogenic range [4 K, 15 K]

This paper brings out results of a measurement campaign aiming to determine the temperature coefficients of synthetic quartz elastic constants at liquid helium temperature. The method is based on the relationship between the resonance frequencies of a quartz acoustic cavity and the elastic constants of the material. The temperature coefficients of the elastic constants are extracted from experimental frequency-temperature data collected from a set of resonators of various cut angles, because of the anisotropy of quartz, measured on the very useful cryogenic range [4 K - 15 K]. The knowledge of these temperature coefficients would allow to further design either quartz temperature sensors or conversely frequency-temperature compensated quartz cuts. With extremely low losses, lower than $10^{-9}$ for the best ones, key applications of such devices are ultra-low loss mechanical systems used in many research areas including frequency control and fundamental measurements. The Eulerian formalism is used in this study to identify the temperature coefficients.Comment: 6 pages,4 figure

Who benefits the most from peer effects within ethnic group ? Empirical evidence on the South African Labour Market

This paper provides evidence that local social interactions within etnic groups may explain the puzzling variations in labour-market outcomes across individuals. Peer effects work first by creating pressure on labor-market participation, second, by conveying information about job opportunities and by raising wages. These effects differ through a selection effect : gender and ethnic groups who are less integrated in the labour market benefit more from peer effect. Finally, networks exhibit decreasing returns. The problems of endogeneity and simultaneity of local peer effects are addressed by using (i) data aggregated at the province level, (ii) the distribution of the sex of the peers' siblings as an instrumental variable and (iii) a quasi-panel data approach relying on the Hausman-Taylor estimator. The importance of social interactions in the labour market suggests that a social multiplier exists and our estimates show that any labour-market shock is magnified with an elasticity of 0.5.Peer effects, development economics, labour, South Africa.

Laser Doppler instrument measures fluid velocity without reference beam

Fluid velocity is measured by focusing laser beam on moving fluid and measuring Doppler shift in frequency which results when radiation is scattered by particles either originally present or deliberately injected into moving fluid

Investigation of air-flow velocity by laser backscatter

Laser light backscatter investigation of air flow velocity in contaminated atmospheres for application to clear air turbulence detector

Swimming using surface acoustic waves

Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs) have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel

Protocol for the monitoring of fauna and flora within Ngamiland, Botswana

During a wildlife expert workshop held at Maun Lodge, 26th & 27th January 2012, the Southern Africa Regional Environmental Program (SAREP) and the Department of Wildlife and National Parks (DWNP) co-hosted a seminar aimed at tackling the issue of the decline of wildlife in Botswana. This document details the outputs of this seminar, and the deliberations that took place follow its conclusion. These deliberations included several additional meetings between SAREP, DWNP and various experts, who subsequently the guidelines for the basic monitoring of flora and fauna within the Ngamiland concessions in Botswana. Designed to mesh seamlessly with the Management Orientated Monitoring System (MOMS), these monitoring data are collected by guides, under the responsibility of concessionaires, for the long-term trend assessment of flora and fauna and observation of wildlife population demographics in Ngamiland. The data collected from the protocol will be applicable at the local and national level. Predator densities and movements, as well as long-term herbivore population trends, will be obtained for management purposes; local game hotspots can be determined, rare species recorded and general dynamics (bush encroachment, stochastic local processes such as disease outbreaks etc.) can be observed and addressed fairly rapidly. The table below outlines wildlife monitoring activities that have been selected for standardised monitorin

New approaches to the management of adult acute lymphoblastic leukemia

Traditional treatment regimens for adult acute lymphoblastic leukemia, including allogeneic hematopoietic cell transplantation, result in an overall survival of about 40%, a figure hardly comparable with the extraordinary 80-90% cure rate currently reported in children. When translated to the adult setting, modern pediatric-type regimens improve the survival to about 60% in young adults. The addition of tyrosine kinase inhibitors for patients with Philadelphia chromosome positive disease and the measurement of minimal residual disease to guide risk stratification and post-remission approaches has led to further improvements in outcomes. Relapsed disease and treatment toxicity - sparing no patient but representing a major concern especially in the elderly - are the most critical current issues awaiting further therapeutic advancement. Recently, there has been considerable progress in understanding the disease biology, specifically the Philadelphia-like signature as well as other high-risk subgroups. In addition, there are several new agents that will undoubtedly contribute to further improvement in the current outcomes. The most promising agents are new the monoclonal antibodies, immunomodulators, and chimeric antigen receptor T cells and, to a lesser extent, several new drugs targeting key molecular pathways involved in leukemic cell growth and proliferation. This review examines the evidence supporting the increasing role of the new therapeutic tools and treatment options in different disease subgroups, including frontline and relapsed/refractory disease. It is now possible to define the best individual approach based on to the emerging concepts of precision medicine

The high-intensity hyperon beam at CERN

A high-intensity hyperon beam was constructed at CERN to deliver Sigma- to experiment WA89 at the Omega facility and operated from 1989 to 1994. The setup allowed rapid changeover between hyperon and conventional hadron beam configurations. The beam provided a Sigma-flux of 1.4 x 10^5 per burst at mean momenta between 330 and 345 Gev/c, produced by about 3 x 10^10 protons of 450 GeV/c . At the experiment target the beam had a Sigma-/pi- ratio close to 0.4 and a size of 1.6 x 3.7 cm^2. The beam particle trajectories and their momenta were measured with a scintillating fibre hodoscope in the beam channel and a silicon microstrip detector at the exit of the channel. A fast transition radiation detector was used to identify the pion component of the beam.Comment: 20 pages, 13 figures. Submitted to Nucl. Instr. Meth.

Ω−\Omega^- Hyperon Decay Modes with the HyperCP Experiment at Fermilab

The HyperCP experiment (Fermilab E871) has the largest recorded sample of $\Omega^-$ hyperon decays, allowing new searches for three rare decay modes, each with five charged tracks in the final state. Results are presented for $\Omega^-\to\Xi^-\pi^+\pi^-$; $\Omega^- \to \Xi^0(1530)\pi^-$; and the flavor-changing neutral-current decay $\Omega^- \to \Xi^-\mu^+\mu^-$. Normalization of these measurements were to the decay $\Omega^- \to \Lambda K^-$ with a five-track topology similar to the signal mode with the subsequent decay of $\Lambda \to p \pi^-$ and $K^- \to \pi^- \pi^+ \pi^-$ in the decay volume.Comment: Presented at the 5th International Conference on Hyperons, Charm and Beauty Hadrons, June 2002., Vancouver, Canada: 4 pages, 5 figures, New Result