Emergence of bound states in ballistic magnetotransport of graphene antidots

An experimental method for detection of bound states around an antidot formed from a hole in a graphene sheet is proposed by measuring the ballistic two terminal conductances. In particularly, we consider the effect of bound states formed by magnetic field on the two terminal conductance and show that one can observe Breit-Wigner like resonances in the conductance as a function of the Fermi level close to the energies of the bound states. In addition, we develop a new numerical method in which the computational effort is proportional to the linear dimensions, instead of the area of the scattering region beeing typical for the existing numerical recursive Green's function method.Comment: 7 pages, 6 figure

Additive trees in the analysis of community data

The paper advocates a more extensive use of additive trees in community ecology. When the distance/dissimilarity coefficient is selected carefully, these trees can illuminate structural aspects that are not obvious otherwise. In particular, starting from squared distances based on presence/absence data, the resulting trees approximate relationships in species richness, a feature not available through other graphical techniques. The construction of additive trees is illustrated by three actual examples, representing different circumstances in the analysis of grassland community data

Lande-like formula for the g factors of hole-nanowire subband edges

We have analyzed theoretically the Zeeman splitting of hole-quantum-wire subband edges. As is typical for any bound state, their g factor depends on both an intrinsic g factor of the material and an additional contribution arising from a finite bound-state orbital angular momentum. We discuss the quantum-confinement-induced interplay between bulk-material and orbital effects, which is nontrivial due to the presence of strong spin-orbit coupling. A compact analytical formula is provided that elucidates this interplay and can be useful for predicting Zeeman splitting in generic hole-wire geometries.Comment: 4 pages, 2 figure

Magnetic and Transport Properties of Fe-Ag granular multilayers

Results of magnetization, magnetotransport and Mossbauer spectroscopy measurements of sequentially evaporated Fe-Ag granular composites are presented. The strong magnetic scattering of the conduction electrons is reflected in the sublinear temperature dependence of the resistance and in the large negative magnetoresistance. The simultaneous analysis of the magnetic properties and the transport behavior suggests a bimodal grain size distribution. A detailed quantitative description of the unusual features observed in the transport properties is given

A Comparison Of Hip And Knee Joint Kinematics Between Two Alpine Ski Ergometers

This study was conducted to determine if hip and knee joint kinematics differed between conditions as subjects "skied" on two alpine ski ergometers. Eleven male recreational skiers, ages 18-23, participated in the study. During the random test, sagittal plane motions of the hip and knee joints were videotaped as subjects skied on each ski ergometer at a slow speed (92 turns/minute) and a fast speed (102 turns/minute). Each subject was vid.eotaped at 30 frames per second during the last thirty seconds of a two minute exercise bout. Three turns were randomly selected and digitized on the Ariel Performance Analysis System (APAS). Relative angular displacements of the left hip and knee were measured and compared. Hip and knee flexion were significantly different between the two ergometers at the fast speed. A comparison of the fast and slow trials revealed that subjects were able to achieve more knee flexion at the fast speed on one ergometer. However, on the other ergometer, the degree of knee flexion was greater at the slow speed. How closely the two ski ergometers simulate actual downhill skiing is unknown and warrants further investigation

Nanoscale spin-polarization in dilute magnetic semiconductor (In,Mn)Sb

Results of point contact Andreev reflection (PCAR) experiments on (In,Mn)Sb are presented and analyzed in terms of current models of charge conversion at a superconductor-ferromagnet interface. We investigate the influence of surface transparency, and study the crossover from ballistic to diffusive transport regime as contact size is varied. Application of a Nb tip to a (In,Mn)Sb sample with Curie temperature Tc of 5.4 K allowed the determination of spin-polarization when the ferromagnetic phase transition temperature is crossed. We find a striking difference between the temperature dependence of the local spin polarization and of the macroscopic magnetization, and demonstrate that nanoscale clusters with magnetization close to the saturated value are present even well above the magnetic phase transition temperature.Comment: 4 page

Single-born XX /XY chimaeric bulls with normal phenotype

International audienc

Strong spin relaxation length dependence on electric field gradients

We discuss the influence of electrical effects on spin transport, and in particular the propagation and relaxation of spin polarized electrons in the presence of inhomogeneous electric fields. We show that the spin relaxation length strongly depends on electric field gradients, and that significant suppression of electron spin polarization can occur as a result thereof. A discussion in terms of a drift-diffusion picture, and self-consistent numerical calculations based on a Boltzmann-Poisson approach shows that the spin relaxation length in fact can be of the order of the charge screening length.Comment: 4 pages, 3 figures, to be presented at PASPSI