Anisotropic magnetoresistance and anisotropic tunneling magnetoresistance due to quantum interference in ferromagnetic metal break junctions

We measure the low-temperature resistance of permalloy break junctions as a function of contact size and the magnetic field angle, in applied fields large enough to saturate the magnetization. For both nanometer-scale metallic contacts and tunneling devices we observe large changes in resistance with angle, as large as 25% in the tunneling regime. The pattern of magnetoresistance is sensitive to changes in bias on a scale of a few mV. We interpret the effect as a consequence of conductance fluctuations due to quantum interference.Comment: 4 pages, 4 figures. Changes in response to reviewer comments. New data provide information about the mechanism causing the AMR and TAM

Experimental verification of position-dependent angular-momentum selection rules for absorption of twisted light by a bound electron

We analyze the multipole excitation of atoms with twisted light, i.e, by a vortex light field that carries orbital angular momentum. A single trapped 40Ca+ ion serves as a localized and positioned probe of the exciting field. We drive the transition and observe the relative strengths of different transitions, depending on the ion's transversal position with respect to the center of the vortex light field. On the other hand, transition amplitudes are calculated for a twisted light field in form of a Bessel beam, a Bessel-Gauss and a Laguerre-Gauss mode. Analyzing experimental obtained transition amplitudes we find agreement with the theoretical predictions at a level of better than 3%. Finally, we propose measurement schemes with two-ion crystals to enhance the sensing accuracy of vortex modes in future experiments.Fil: Afanasev, Andrei. The George Washington University; Estados UnidosFil: Carlson, Carl E.. College of William and Mary; Estados UnidosFil: Schmiegelow, Christian Tomás. Johannes Gutenberg University Mainz. Institute of Physics; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Schulz, Jonas. Johannes Gutenberg University Mainz. Institute of Physics; AlemaniaFil: Schmidt-kaler, Ferdinand. Johannes Gutenberg University Mainz. Institute of Physics; AlemaniaFil: Solyanik, Maria. The George Washington University; Estados Unido

Management of Acute Stroke in the Older Person.

The majority of people who suffer a stroke are older adults. The last two decades have brought major progress in the diagnosis and management of stroke, which has led to significant reductions in mortality, long-term disability, and the need for institutional care. However, acute, interventional and preventative treatments have mostly been trialled in younger age groups. In this article we will provide an overview of the evidence for acute stroke treatments in relation to age, discuss special considerations in the older person, and contemplate patient choice, quality of life, and end-of-life-decisions

The critical pressures of gas vesicles in Planktorhrix rubescens in relation tothe depth of winter mixing in Lake Zürich, Switzerland

The vertical distribution of the cyanobacterium Planktothrir (Oscillazoria) rubescens in Lake Zürich was investigated from March 1993 to June 1995 by collecting filaments on filters and measuring them by epifluorescence microscopy and computer image analysis. The initial population, which began to stratify in April, decreased by up to 99% by June. During the summer, the population peaked at depths of 8-15 m; it reached a maximum areal filament-volume concentration of -60 cm −3 of lake surface in early September and was then entrained in the deepening surface layer. It became mixed progressively deeper, to the lake bottom in the cold winter of 1993-94, but less completely in the milder winter of 1994-95. Most of the filaments remained viable during the winter. At the end of the mild winter of 1994-5, 70% of filaments in the water column retained buoyancy, but after the cold winter of 1996-7 only 22% were buoyant. Few remained buoyant below 80 m, where the hydrostatic pressure caused gas vesicle collapse. The proportion that remain buoyant decreases with the depth and duration of winter mixing, and increases with the critical collapse pressure (Pc) of the gas vesicles, which provide buoyancy. Strains of P.rubescens isolated from Lake Zürich differed in mean (Pc) of their gas vesicles, from 0.9 to 1.1 MPa, the highest values in freshwater cyanobacteria. Allowing for a turgor pressure of 0.2 MPa. these strains would remain buoyant at depths down to 70 and 90 m, respectively. Natural selection for gas vesicles of high (Pc) will operate by increasing the proportion of filaments that remain buoyant in the upper parts of the water column after circulation to various depths during the winter because only buoyant filaments will form the inoculum for the following seaso

How to improve drug dosing for patients with renal impairment in primary care - a cluster-randomized controlled trial

Background: Patients with chronic kidney disease (CKD) are at increased risk for inappropriate or potentially harmful prescribing. The aim of this study was to examine whether a multifaceted intervention including the use of a software programme for the estimation of creatinine clearance and recommendation of individual dosage requirements may improve correct dosage adjustment of relevant medications for patients with CKD in primary care. Methods: A cluster-randomized controlled trial was conducted between January and December 2007 in small primary care practices in Germany. Practices were randomly allocated to intervention or control groups. In each practice, we included patients with known CKD and elderly patients (>=70 years) suffering from hypertension. The practices in the intervention group received interactive training and were provided a software programme to assist with individual dose adjustment. The control group performed usual care. Data were collected at baseline and at 6 months. The outcome measures, analyzed across individual patients, included prescriptions exceeding recommended maximum daily doses, with the primary outcome being prescriptions exceeding recommended standard daily doses by 30% or more. Results: Data from 44 general practitioners and 404 patients are included. The intervention was effective in reducing prescriptions exceeding the maximum daily dose per patients, with a trend in reducing prescriptions exceeding the standard daily dose by more than 30%. Conclusions: A multifaceted intervention including the use of a software program effectively reduced inappropriately high doses of renally excreted medications in patients with CKD in the setting of small primary care practices