Measurement of the elastic scattering cross section of neutrons from argon and neon

Background: The most significant source of background in direct dark matter searches are neutrons that scatter elastically from nuclei in the detector's sensitive volume. Experimental data for the elastic scattering cross section of neutrons from argon and neon, which are target materials of interest to the dark matter community, were previously unavailable. Purpose: Measure the differential cross section for elastic scattering of neutrons from argon and neon in the energy range relevant to backgrounds from (alpha,n) reactions in direct dark matter searches. Method: Cross-section data were taken at the Triangle Universities Nuclear Laboratory (TUNL) using the neutron time-of-flight technique. These data were fit using the spherical optical model. Results: The differential cross section for elastic scatting of neutrons from neon at 5.0 and 8.0 MeV and argon at 6.0 MeV was measured. Optical-model parameters for the elastic scattering reactions were determined from the best fit to these data. The total elastic scattering cross section for neon was found to differ by 6% at 5.0 MeV and 13% at 8.0 MeV from global optical-model predictions. Compared to a local optical-model for 40Ar, the elastic scattering cross section was found to differ from the data by 8% at 6.0 MeV. Conclusions: These new data are important for improving Monte-Carlo simulations and background estimates for direct dark matter searches and for benchmarking optical models of neutron elastic scattering from these nuclei

The clinical utility and cost effectiveness of routine thyroid screening in adult psychiatric patients presenting at Stikland Hospital, Cape Town, South Africa

Objective: The use of thyroid tests to assess psychiatric patients remains debatable. Therefore, this study was conducted to examine the utility and cost effectiveness of the current protocol used in thyroid testing in adult psychiatric patients presenting at Stikland Hospital, Cape Town, South Africa. Method: This was a retrospective chart review conducted at Stikland Hospital between 1 January 2000 and 31 December 2005. The following data was recorded: demographic variables, clinical diagnoses at admission and discharge, number of days from admission to a thyroid test request, the reason for thyroid screening, number of thyroid tests, their yield and costs involved, as well as the action taken following an abnormal thyroid test result. Results: The mean age of patients (n = 1080: n = 364 male, n = 716 female) was 42.8 years (SD ±16.6). Pre-existing thyroid disease was documented in 70 (6%) of patients. Normal Thyroid Stimulating Hormone (TSH) test results significantly (p = 0.0001) increased, whilst abnormal TSH test results significantly (p = 0.0001) decreased from baseline to follow-up. Except for gender, the outcome of TSH screening was independent of demographic and clinical diagnoses. Only 16% of TSH tests yielded clinically significant results. Conclusion: The findings of this study do not support the early, routine screening for thyroid dysfunction in psychiatric patients at this facility. It is possible that thyroid screening may present with transient abnormalities of no particular clinical significance, and would therefore not be a cost effective practice.Keywords: Psychiatry; Screening; Thyroid abnormality; Thyroid stimulating hormon

Quantum chaos in a Bose-Hubbard dimer with modulated tunnelling

In the large-$N$, classical limit, the Bose-Hubbard dimer undergoes a transition to chaos when its tunnelling rate is modulated in time. We use exact and approximate numerical simulations to determine the features of the dynamically evolving state that are correlated with the presence of chaos in the classical limit. We propose the statistical distance between initially similar number distributions as a reliable measure to distinguish regular from chaotic behaviour in the quantum dynamics. Besides being experimentally accessible, number distributions can be efficiently reconstructed numerically from binned phase-space trajectories in a truncated Wigner approximation. Although the evolving Wigner function becomes very irregular in the chaotic regions, the truncated Wigner method is nevertheless able to capture accurately the beyond mean-field dynamics.Comment: 10 pages, 10 figure

Banda Aceh-The Value of Earth Observation Data in Disaster Recovery and Reconstruction: A Case Study

On 26 December 2004, Banda Aceh in Indonesia was at the center of one of the worst natural disasters to affect mankind. Large amounts of international aid poured in to assist in the relief and reconstruction efforts. Amongst this effort, were investments in basic earth observation data from in-situ, airborne and space observations. While the use of this data is assumed to be crucial, few efforts have gone into quantifying the benefits of its acquisition. The objectives of this study were to interview a cross-section of agencies operating in Banda Aceh and across the province of Nanggroe Aceh Darussalam on the use, sources and quality of earth observation data in the relief/reconstruction effort; and to analyze and quantify the value that earth observation data brings to the relief/reconstruction effort based on the survey results and specific examples. Key findings from the interviews point to an overall improvement in the spatial data situation since the tsunami. Problems identified included insufficient training, lack of timely data and sometimes poor spatial resolution. Specific examples of the cost-benefits of earth observation data were typically on the order of millions of dollars and involved large time savings. IIASA is one of 12 partners in the European Union sponsored project "Global Earth Observation/Benefit Estimation: Now, Next and Emerging" (GEO-BENE). Additional GEO-BENE partner countries include Germany, Switzerland, Slovakia, Netherlands, Finland, South Africa and Japan. Within GEO-BENE we are developing methodologies and analytical tools to assess societal benefits of GEO in nine societal benefit areas- one of which is disasters. The tsunami affected province of Nanggroe Aceh Darussalam, and specifically Banda Aceh, has been selected as a case study. Other case studies representing different societal benefit areas include: biodiversity in South Africa, health and climate in Finland, fire in Europe, etc. For more information please refer to: www.geo-bene.eu