A case report: isolation of alysiella filiformis from pig"s lungs

Alysiella filiformis is considered a common resident in the oral cavities of many animals. All reports of Alysiella indicate that it is restricted to the oral cavity of warm-blooded vertebrates, where it apparently is nonpathogenic. However, increased losses of young pigs occured in one farm in Serbia. Spumous content in bronchia and partly clotted blood in blood vesels o f the lungs were present. Characteristic signs of oedema disease were present and E. coli serogroup 0139 was isolated. Furthermore, Alysiella filiformis was the single agent isolated from the lungs of diseased pigs. This is the first isolation of Alysiella filiformis from pig lungs

Spin relaxation in the impurity band of a semiconductor in the external magnetic field

Spin relaxation in the impurity band of a 2D semiconductor with spin-split spectrum in the external magnetic field is considered. Several mechanisms of spin relaxation are shown to be relevant. The first one is attributed to phonon-assisted transitions between Zeeman sublevels of the ground state of an isolated impurity, while other mechanisms can be described in terms of spin precession in a random magnetic field during the electron motion over the impurity band. In the later case there are two contributions to the spin relaxation: the one given by optimal impurity configurations with the hop-waiting time inversely proportional to the external magnetic field and another one related to the electron motion on a large scale. The average spin relaxation rate is calculated

Low Temperature Behavior of the Vortex Lattice in Unconventional Superconductors

We study the effect of the superconducting gap nodes on the vortex lattice properties of high temperature superconductors at very low temperatures. The nonlinear, nonlocal and nonanalytic nature of this effect is shown to have measurable consequences for the vortex lattice geometry and the effective penetration depth in the mixed state as measured by muon-spin-rotation experiments.Comment: 3 figures and extensive discussion added, Version to appear in September 1 issue of PR

Electronic States of Magnetic Quantum Dots

We study quantum states of electrons in magnetically doped quantum dots as a function of exchange coupling between electron and impurity spins, the strength of Coulomb interaction, confining potential, and the number of electrons. The magnetic phase diagram of quantum dots, doped with a large number of magnetic Mn impurities, can be described by the energy gap in the spectrum of electrons and the mean field electron-Mn exchange coupling. A competition between these two parameters leads to a transition between spin-unpolarized and spin-polarized states, in the absence of applied magnetic field. Tuning the energy gap by electrostatic control of nonparabolicity of the confining potential can enable control of magnetization even at the fixed number of electrons. We illustrate our findings by directly comparing Mn-doped quantum dots with parabolic and Gaussian confining potential.Comment: 5 pages, 5 figures, Part of Focus on Spintronics in Reduced Dimension

Electronic measurement and control of spin transport in Silicon

The electron spin lifetime and diffusion length are transport parameters that define the scale of coherence in spintronic devices and circuits. Since these parameters are many orders of magnitude larger in semiconductors than in metals, semiconductors could be the most suitable for spintronics. Thus far, spin transport has only been measured in direct-bandgap semiconductors or in combination with magnetic semiconductors, excluding a wide range of non-magnetic semiconductors with indirect bandgaps. Most notable in this group is silicon (Si), which (in addition to its market entrenchment in electronics) has long been predicted a superior semiconductor for spintronics with enhanced lifetime and diffusion length due to low spin-orbit scattering and lattice inversion symmetry. Despite its exciting promise, a demonstration of coherent spin transport in Si has remained elusive, because most experiments focused on magnetoresistive devices; these methods fail because of universal impedance mismatch obstacles, and are obscured by Lorentz magnetoresistance and Hall effects. Here we demonstrate conduction band spin transport across 10 microns undoped Si, by using spin-dependent ballistic hot-electron filtering through ferromagnetic thin films for both spin-injection and detection. Not based on magnetoresistance, the hot electron spin-injection and detection avoids impedance mismatch issues and prevents interference from parasitic effects. The clean collector current thus shows independent magnetic and electrical control of spin precession and confirms spin coherent drift in the conduction band of silicon.Comment: Single PDF file with 4 Figure

Charge current in ferromagnet-superconductor junction with pairing state of broken time-reversal symmetry

We calculate the tunneling conductance spectra of a ferromagnetic metal/insulator/superconductor using the Blonder-Tinkham-Klapwijk (BTK) formulation. Two possible states for the superconductor are considered with the time reversal symmetry ($\cal{T}$) broken, i.e., $d_{x^2-y^2}+is$, or $d_{x^2-y^2}+id_{xy}$. In both cases the tunneling conductance within the gap is suppressed with the increase of the exchange interaction due to the suppression of the Andreev reflection. In the $(d_{x^2-y^2}+is)$-wave case the peaks that exist when the ferromagnet is a normal metal in the amplitude of the s-wave component due to the bound state formation are reduced symmetrically, with the increase of the exchange field, while in the $(d_{x^2-y^2}+id_{xy})$-wave case the residual density of states within the gap develops a dip around E=0 with the increase of the exchange field. These results would be useful to discriminate between $\cal{T}$-broken pairing states near the surface in high-$T_c$ superconductorsComment: 17 pages with 11 figure

Spin-orbit interaction effects on the magnetoplasmon spectrum of modulated two-dimensional electron gas

We present a theoretical study of magnetoplasmon spectrum of a two-dimensional electron gas in the presence of Rashba spin-orbit interaction (RSOI), one-dimensional weak electric modulation and a perpendicular magnetic field. The intra-Landau-band magnetoplasmon spectrum is determined in the presence of spin-orbit interaction within the self consistent field approach at finite temperature. Due to Rashba effect, the spin of finite-momentum electrons feels a magnetic field perpendicular to the electron momentum in the inversion plane. The magnetoplasmon spectrum of the modulated two-dimensional electron gas (M2DEG) system is found to exhibit beating of Weiss oscillations due to Rashba effect which is the focus of this work. This effect is absent in the magnetoplasmon spectrum of M2DEG if Rashba spin-orbit interaction is not taken into account. In addition, our finite temperature theory ficilitates analysis of effects of temperature on the magnetoplasmon spectrum of M2DEG in the presence of RSOI. We find that the beating pattern is damped but continues to persist at a finite but low temperature.Comment: Accepted in Physica

Angular Dependence of the Nonlinear Transverse Magnetic Moment of YBCO in the Meissner state

The angular dependence of the nonlinear transverse magnetic moment of untwinned high-quality single crystals of optimally doped YBCO have been studied at a temperature of 2.5K using a low frequency AC technique. The absence of any signature at angular period 2\pi/4is analyzed in light of the numerical predictions of such a signal for a pure d-wave order parameter with line nodes. Implications of this null result for the existence of a non-zero gap at all angles on the Fermi surface are discussed.Comment: 4 pages, 2 ps figures (submitted to Phys. Rev. Lett.