Ballistic electron transport through magnetic domain walls

Electron transport limited by the rotating exchange-potential of domain walls is calculated in the ballistic limit for the itinerant ferromagnets Fe, Co, and Ni. When realistic band structures are used, the domain wall magnetoresistance is enhanced by orders of magnitude compared to the results for previously studied two-band models. Increasing the pitch of a domain wall by confinement in a nano-structured point contact is predicted to give rise to a strongly enhanced magnetoresistance.Comment: 4 pages, 2 figures; to appear in PRB as a brief repor

Primary Shoulder Arthroplasty Versus Conservative Treatment for Comminuted Proximal Humeral Fractures: A Systematic Literature Review

The objective was to identify whether arthroplasty or conservative treatment is the best available treatment for three- and four-part proximal humeral fractures by analyzing the outcome measure of the Constant score. We conducted an electronic search. The systematic review included 33 studies encompassing 1096 patients with three- or four-part proximal humeral fractures that used the Constant score as outcome measure. The mean Constant score in the conservative group was 66.5 and in the arthroplasty group was 55.5. The difference could be attributed to selection bias, unreliable classification of the fractures and inter-observer differences in the assessment of the Constant score

Universal distribution of transparencies in highly conductive Nb/AlOx_x/Nb junctions

We report the observation of the universal distribution of transparencies, predicted by Schep and Bauer [Phys. Rev. Lett. {\bf 78}, 3015 (1997)] for dirty sharp interfaces, in uniform Nb/AlO$_x$/Nb junctions with high specific conductance ($10^8$ Ohm$^{-1}$cm$^{-2}$). Experiments used the BCS density of states in superconducting niobium for transparency distribution probing. Experimental results for both the dc $I-V$ curves at magnetic-field-suppressed supercurrent and the Josephson critical current in zero magnetic field coincide remarkably well with calculations based on the multimode theory of multiple Andreev reflections and the Schep-Bauer distribution.Comment: 4 pages, 4 figures, references adde

Spin Torques in Ferromagnetic/Normal Metal Structures

Recent theories of spin-current-induced magnetization reversal are formulated in terms of a spin-mixing conductance $G^{mix}$. We evaluate $G^{mix}$ from first-principles for a number of (dis)ordered interfaces between magnetic and non-magnetic materials. In multi-terminal devices, the magnetization direction of a one side of a tunnel junction or a ferromagnetic insulator can ideally be switched with negligible charge current dissipation.Comment: 4 pages, 1 figur

Scattering theory of interface resistance in magnetic multilayers

The scattering theory of transport has to be applied with care in a diffuse environment. Here we discuss how the scattering matrices of heterointerfaces can be used to compute interface resistances of dirty magnetic multilayers. First principles calculations of these interface resistances agree well with experiments in the CPP (current perpendicular to the interface plane) configuration.Comment: submitted to J. Phys. D (special issue at the occasion of Prof. T. Shinjo's 60th birthday

Participation in and adherence to physical exercise after completion of primary cancer treatment

Contains fulltext : 171131.pdf (publisher's version ) (Open Access)BACKGROUND: The purpose of this study was to identify demographic, clinical, psychosocial, physical and environmental factors that are associated with participation in and adherence to a combined resistance and endurance exercise program among cancer survivors, shortly after completion of primary cancer treatment. Data from the randomized controlled Resistance and Endurance exercise After ChemoTherapy (REACT) study were used for this study. METHODS: The participants of the REACT study were randomly allocated to either a high intensity (HI) or low-to-moderate intensity (LMI) exercise program. Patients' participation rate was defined as the cancer survivors' decision to participate in the REACT study. Exercise adherence reflected participants' attendance to the scheduled exercise sessions and their compliance to the prescribed exercises. High session attendance rates were defined as attending at least 80 % of the sessions. High compliance rates were defined as performing at least of 90 % of the prescribed exercise across all sessions. Correlates of exercise adherence were studied separately for HI and LMI exercise. Demographic, clinical, and physical factors were assessed using self-reported questionnaires. Relevant clinical information was extracted from medical records. Multivariable logistic regression analyses were applied to identify correlates that were significantly associated with participation, high session attendance, high compliance with resistance and high compliance with endurance exercises. RESULTS: Participants were more likely to have higher education, be non-smokers, have lower psychological distress, higher outcome expectations, and perceive more exercise barriers than non-participants. In HI exercise, higher self-efficacy was significantly associated with high session attendance and high compliance with endurance exercises, and lower psychological distress was significantly associated with high compliance with resistance exercises. In LMI exercise, being a non-smoker was significantly associated with high compliance with resistance exercises and higher BMI was significantly associated with high compliance with resistance and endurance exercises. Furthermore, breast cancer survivors were less likely to report high compliance with resistance and endurance exercises in LMI exercise compared to survivors of other types of cancer. The discriminative ability of the multivariable models ranged from 0.62 to 0.75. CONCLUSION: Several demographic, clinical and psychosocial factors were associated with participation in and adherence to exercise among cancer survivors. Psychosocial factors were more strongly associated with adherence in HI than LMI exercise. TRIAL REGISTRATION: This study was registered at the Netherlands Trial Register [ NTR2153 ] on the 5(th) of January 2010

Shot Noise in Mesoscopic Diffusive Andreev Wires

We study shot noise in mesoscopic diffusive wires between a normal and a superconducting terminal. We particularly focus on the regime, in which the proximity-induced reentrance effect is important. We will examine the difference between a simple Boltzmann-Langevin description, which neglects induced correlations beyond the simple conductivity correction, and a full quantum calculation. In the latter approach, it turns out that two Andreev pairs propagating coherently into the normal metal are anti-correlated for E<E_c, where E_c=D/L^2 is the Thouless energy. In a fork geometry the flux-sensitive suppression of the effective charge was confirmed experimentally.Comment: 12 pages, proceedings of the NATO ARW MQO, Bled, Sloveni

Observation of a controllable PI-junction in a 3-terminal Josephson device

Recently Baselmans et al. [Nature, 397, 43 (1999)] showed that the direction of the supercurrent in a superconductor/normal/superconductor Josephson junction can be reversed by applying, perpendicularly to the supercurrent, a sufficiently large control current between two normal reservoirs. The novel behavior of their 4-terminal device (called a controllable PI-junction) arises from the nonequilibrium electron energy distribution established in the normal wire between the two superconductors. We have observed a similar supercurrent reversal in a 3-terminal device, where the control current passes from a single normal reservoir into the two superconductors. We show theoretically that this behavior, although intuitively less obvious, arises from the same nonequilibrium physics present in the 4-terminal device. Moreover, we argue that the amplitude of the PI-state critical current should be at least as large in the 3-terminal device as in a comparable 4-terminal device.Comment: 4 pages, 4 figures, to appear in Physical Review B Rapid Communication

Spin-accumulation and Andreev-reflection in a mesoscopic ferromagnetic wire

The electron transport though ferromagnetic metal-superconducting hybrid devices is considered in the non-equilibrium Green's function formalism in the quasiclassical approximation. Attention if focused on the limit in which the exchange splitting in the ferromagnet is much larger than the superconducting energy gap. Transport properties are then governed by an interplay between spin-accumulation close to the interface and Andreev reflection at the interface. We find that the resistance can either be enhanced or lowered in comparison to the normal case and can have a non-monotonic temperature and voltage dependence. In the non-linear voltage regime electron heating effects may govern the transport properties, leading to qualitative different behaviour than in the absence of heating effects. Recent experimental results on the effect of the superconductor on the conductance of the ferromagnet can be understood by our results for the energy-dependent interface resistance together with effects of spin- accumulation without invoking long range pairing correlations in the ferromagnet.Comment: 15 pages, 12 figures included, submitted to PR

Impurity Scattering from δ\delta-layers in Giant Magnetoresistance Systems

The properties of the archetypal Co/Cu giant magnetoresistance (GMR) spin-valve structure have been modified by the insertion of very thin (sub-monolayer) $\delta$-layers of various elements at different points within the Co layers, and at the Co/Cu interface. Different effects are observed depending on the nature of the impurity, its position within the periodic table, and its location within the spin-valve. The GMR can be strongly enhanced or suppressed for various specific combinations of these parameters, giving insight into the microscopic mechanisms giving rise to the GMR.Comment: 5 pages, 2 figure