Neutron-diffraction study of field-induced transitions in the heavy-fermion compound Ce2RhIn8

We present neutron diffraction measurements in high magnetic fields (0 to 14.5 T) and at low temperatures (2.5, 2.3, 0.77 and 0.068 K) on single crystals of the tetragonal heavy fermion antiferromagnet Ce2RhIn8. For B//[110] the field dependence of selected magnetic and nuclear reflections reveals that the material undergoes several transitions, the temperature dependence of which suggests a complex B-T phase diagram. We present the detailed evolution of the integrated intensities of selected reflections and discuss the associated field-induced transitions.Comment: 12 pages, 3 figures Proceeding Euro-conference "Properties of Condensed Matter probed by x-ray and neutron scattering"; to appear in Physica

Vortex pinning in high-Tc materials via randomly oriented columnar defects, created by GeV proton-induced fission fragments

Extensive work has shown that irradiation with 0.8 GeV protons can produce randomly oriented columnar defects (CD's) in a large number of HTS materials, specifically those cuprates containing Hg, Tl, Pb, Bi, and similar heavy elements. Absorbing the incident proton causes the nucleus of these species to fission, and the recoiling fission fragments create amorphous tracks, i.e., CD's. The superconductive transition temperature Tc decreases linearly with proton fluence and we analyze how the rate depends on the family of superconductors. In a study of Tl-2212 materials, adding defects decreases the equilibrium magnetization Meq(H) significantly in magnitude and changes its field dependence; this result is modeled in terms of vortex pinning. Analysis of the irreversible magnetization and its time dependence shows marked increases in the persistent current density and effective pinning energy, and leads to an estimate for the elementary attempt time for vortex hopping, tau ~ 4x10^(-9) s.Comment: Submitted to Physica C; presentation at ISS-2001. PDF file only, 13 pp. tota

Non-Fermi Liquid behavior in CeIrIn5_5 near a metamagnetic transition

We present specific heat and resistivity study of CeIrIn5 in magnetic fields up to 17 T and temperature down to 50 mK. Both quantities were measured with the magnetic field parallel to the c-axis (H || [001]) and within the a-b plane (H \perp [001]). Non-Fermi-liquid (NFL) behavior develops above 12 T for H || [001]. The Fermi liquid state is much more robust for H \perp [001] and is suppressed only moderately at the highest applied field. Based on the observed trends and the proximity to a metamagnetic phase transition, which exists at fields above 25 T for H || [001], we suggest that the observed NFL behavior in CeIrIn5 is a consequence of a metamagnetic quantum critical point.Comment: 5 pages, 4 figures, submitted to Phys. Rev. Letter

Selectron Studies at e-e- and e+e- Colliders

Selectrons may be studied in both e-e- and e+e- collisions at future linear colliders. Relative to e+e-, the e-e- mode benefits from negligible backgrounds and \beta threshold behavior for identical selectron pair production, but suffers from luminosity degradation and increased initial state radiation and beamstrahlung. We include all of these effects and compare the potential for selectron mass measurements in the two modes. The virtues of the e-e- collider far outweigh its disadvantages. In particular, the selectron mass may be measured to 100 MeV with a total integrated luminosity of 1 fb^-1, while more than 100 fb^-1 is required in e+e- collisions for similar precision.Comment: 16 pages, 11 figure

Laboratory and field studies related to the Hydrology/Radionuclide Migration Project

This annual report describes research conducted in FY 1990 by Los Alamos National Laboratory for the Hydrology/Radionuclide Migration Project. This multi-agency project measures the underground movement of radionuclides related to nuclear testing at the Nevada Test Site. This project continues the long-term experiment at the site of the Cambric nuclear test. Water pumped from a well adjacent to the explosion cavity continues to show decreasing amounts of tritium and Krypton 85 but no Cesium 139. Analyses of drillback debris shows a distinction between refractory and volatile materials in respect to both their location in the test cavity and their leachability with groundwater. We surveyed materials used during nuclear testing to evaluate any post-test hazard; we concluded that most such materials pose a minimal hazard. The Los Alamos drilling program provided an opportunity for us to sample a collapsed zone above the cavity of a test, which was fired 2 years ago. We continue our research in colloid characterization and in detection of low levels of Technetium 99 in Nevada Test Site water. During FY 1990, we drilled a new hole in the Yucca Flat area to study radionuclide migration. This report also describes Los Alamos management and planning activities in support of this project. 20 refs., 2 figs., 14 tabs

Laboratory and field studies related to the Hydrology/Radionuclide Migration Project

This annual report describes research conducted in FY1989 by Los Alamos National Laboratory in the Hydrology/Radionuclide Migration Project. This work, which is done in coordination with several other organizations, relates to the movement of radionuclides underground at the Nevada Test Site. This project continues the long-term monitoring of tritium and fission product concentrations in water at the Cambric study area. As water has been pumped from an adjacent well, radionuclide concentrations in the cavity region have diminished to near the limits of detection. Neutral and anionic radionuclides have been measured in the effluent of the pumped well, but cations such as {sup 90}Sr and {sup 137}Cs have not been detected. This year a study was initiated to measure the spatial distribution of refractory and volatile elements in the cavity/chimney regions of underground nuclear tests. Differences in both distribution and leachability were observed for the two sites studied. Colloidal material from the Cambric site was collected and analyzed by transmission electron microscopy. We believe we were able to distinguish natural colloids from those introduced in drilling fluids. We tested the hypothesis that the {sup 87}Sr/{sup 86}Sr isotopic ratio would be useful in making this distinction and concluded that it was not. We reported a first measurement of {sup 99}Tc in water from the Cambric site. We also participated in the hydrologic study of a highly pressurized zone in the tuff aquifer at the Nevada Test Site that was apparently created by nuclear testing. 25 refs

Counting the cost of preventable diabetes-related lower limb amputations at a single district hospital in KwaZulu-Natal: what does this mean, what can be done?

Background: Healthcare policy decisions are driven by many factors, including cost, hence the need to show costs of diabetes mellitus-related lower limb amputations (DMLLA) to inform amendments to health care. Substantial decreases in amputation rates are associated with specialised podiatry foot clinics and ongoing foot education, as per national guidelines on the multidisciplinary team approach (MDTA) to diabetes health care. There are only two podiatry posts in KwaZulu-Natal (KZN) state health department (DoH).Objectives: Aims were to draft the medical costs for 660 DMLLA at Greys Hospital for the period 2013–2017; to extrapolate costs on annual DMLLA in KZN; to outline socio-economic costs for future investigation; to present evidence that podiatry in the MDTA can decrease numbers of DMLLA.Methods: A retrospective review on clinical data captured in real time and maintained by the Pietermaritzburg Metropolitan Trauma Service (PMTS) and Surgical Service (PMSS) was performed. Costs were analysed on data for 660 patients’ DMLLA at Greys Hospital between 2013 and 2017, and psychological and socio-economic costs via literature review.Results: Medical care at Greys Hospital for 660 DMLLA in the five years cost in excess of ZAR 213 million. Extrapolated to the 1 231 diabetic amputations (2014) equals an annual cost to KZN DoH in excess of ZAR 398 million. Personal, family loss and socio-economic costs are estimated in excess of ZAR five million per amputee, resulting in further cost of ZAR 6.155 billion per annum to KZN. Extrapolation across 11 provinces signifies a national cost of at least ZAR 68 billion.Conclusions: We present a gauge of the cost of DMLLA to KZN and national health. Substantial possible socio-economic losses compound these. The role of podiatrists within MDTA teams has an evidence base to prevent DMLLA

Advance telephone calls ahead of reminder questionnaires increase response rate in non-responders compared to questionnaire reminders only : The RECORD phone trial

Peer reviewedPublisher PD