2,947 research outputs found
Spin current swapping and Hanle spin Hall effect in the two dimensional electron gas
We analyze the effect known as "spin current swapping" (SCS) due to
electron-impurity scattering in a uniform spin-polarized two-dimensional
electron gas. In this effect a primary spin current (lower index for
spatial direction, upper index for spin direction) generates a secondary spin
current if , or , with , if . Contrary
to naive expectation, the homogeneous spin current associated with the uniform
drift of the spin polarization in the electron gas does not generate a swapped
spin current by the SCS mechanism. Nevertheless, a swapped spin current will be
generated, if a magnetic field is present, by a completely different mechanism,
namely, the precession of the spin Hall spin current in the magnetic field. We
refer to this second mechanism as Hanle spin Hall effect, and we notice that it
can be observed in an experiment in which a homogeneous drift current is passed
through a uniformly magnetized electron gas. In contrast to this, we show that
an unambiguous observation of SCS requires inhomogeneous spin currents, such as
those that are associated with spin diffusion in a metal, and no magnetic
field. An experimental setup for the observation of the SCS is therefore
proposed.Comment: 8 pages, 5 figure
Effective pseudopotential for energy density functionals with higher order derivatives
We derive a zero-range pseudopotential that includes all possible terms up to
sixth order in derivatives. Within the Hartree-Fock approximation, it gives the
average energy that corresponds to a quasi-local nuclear Energy Density
Functional (EDF) built of derivatives of the one-body density matrix up to
sixth order. The direct reference of the EDF to the pseudopotential acts as a
constraint that divides the number of independent coupling constants of the EDF
by two. This allows, e.g., for expressing the isovector part of the functional
in terms of the isoscalar part, or vice versa. We also derive the analogous set
of constraints for the coupling constants of the EDF that is restricted by
spherical, space-inversion, and time-reversal symmetries.Comment: 18 LaTeX pages, 2 EPS Figures, 27 Tables, and 18 files of the
supplemental material (LaTeX, Mathematica, and Fortran), introduction
rewritten, table XXVII and figure 2 corrected, in press in Physical Review
Spin Hall and Edelstein effects in metallic films: from 2D to 3D
A normal metallic film sandwiched between two insulators may have strong
spin-orbit coupling near the metal-insulator interfaces, even if spin-orbit
coupling is negligible in the bulk of the film. In this paper we study two
technologically important and deeply interconnected effects that arise from
interfacial spin-orbit coupling in metallic films. The first is the spin Hall
effect, whereby a charge current in the plane of the film is partially
converted into an orthogonal spin current in the same plane. The second is the
Edelstein effect, in which a charge current produces an in-plane, transverse
spin polarization. At variance with strictly two-dimensional Rashba systems, we
find that the spin Hall conductivity has a finite value even if spin-orbit
interaction with impurities is neglected and "vertex corrections" are properly
taken into account. Even more remarkably, such finite value becomes "universal"
in a certain configuration. This is a direct consequence of the spatial
dependence of spin-orbit coupling on the third dimension, perpendicular to the
film plane. The non-vanishing spin Hall conductivity has a profound influence
on the Edelstein effect, which we show to consist of two terms, the first with
the standard form valid in a strictly two-dimensional Rashba system, and a
second arising from the presence of the third dimension. Whereas the standard
term is proportional to the momentum relaxation time, the new one scales with
the spin relaxation time. Our results, although derived in a specific model,
should be valid rather generally, whenever a spatially dependent Rashba
spin-orbit coupling is present and the electron motion is not strictly
two-dimensional.Comment: 23 pages, 3 figure
Artificial intelligence for heart rate variability analyzing with arrhythmias
Introduction. Existing standards of Heart Rate Variability (HRV) technology limit its use to sinus rhythm. A small number of extrasystoles is allowed, if the device used has special procedures for the detection and replacement of ectopic complexes. However, it is important to expand the indicated limits of the applicability of the HRV technology. This specially regards the cases when the HRV technology looks promising in the diagnostics, as, for example, in atrial fibrillation and atrial flutter.
Materials and Methods. All ECG measurements were performed on XAI-MEDICA® equipment and software. Processing of the obtained RR Series was carried out using the software Kubios® HRV Standard. All recommended HRV characteristics for Time-Domain, Frequency-Domain and Nonlinear were calculated.
The purpose of the work. The article presents an artificial intelligence (AI) procedure for detecting episodes of arrhythmias
and reconstruction of core patient’s rhythm, and demonstrates the efficacy of its use for the HRV analysis in patients with varying degrees of arrhythmias.
The results of the study. It was shown efficiency of developed artificial intelligence procedure for HRV analyzing of patients with different level of arrhythmias. These were demonstrated for Time-Domain, Frequency-Domain and Nonlinear methods. The direct inclusion into review of Arrhythmia Episodes and the use of the initial RR Series leads to a significant distortion of the results of the HRV analysis for the whole set of methods and for all considered options for arrhythmia.
Conclusion. High efficacy of operation of the procedure AI core rhythm extraction from initial RR Series for patients with arrhythmia was reported in all cases
Theory of the spin galvanic effect at oxide interfaces
The spin galvanic effect (SGE) describes the conversion of a non-equilibrium
spin polarization into a transverse charge current. Recent experiments have
demonstrated a large conversion efficiency for the two-dimensional electron gas
formed at the interface between two insulating oxides, LaAlO and SrTiO.
Here we analyze the SGE for oxide interfaces within a three-band model for the
Ti t orbitals which displays an interesting variety of effective
spin-orbit couplings in the individual bands that contribute differently to the
spin-charge conversion. Our analytical approach is supplemented by a numerical
treatment where we also investigate the influence of disorder and temperature,
which turns out to be crucial to provide an appropriate description of the
experimental data.Comment: 5 pages, 3 figure
Software theory change for resilient near-complete specifications
Software evolution and its laws are essential for antifragile system design and development. In this paper we model early-stage
perfective and corrective changes to software system architecture in terms of logical operations of expansion and safe contraction
on a theory. As a result, we formulate an inference-based notion of property specification resilience for computational systems,
intended as resistance to change. The individuated resilient core of a software system is used to characterize adaptability properties
A typed natural deduction calculus to reason about secure trust
System integrity can be put at risk by unintentional transitivity of resource access. We present a natural deduction calculus for an access control model with an explicit trust function on resources. Its inference relation is designed to limit unintentionally transitive access from untrusted parties. We also offer results for ordered cut and normalization related to security and hint at a prototype implementation
Effect of insulin glargine on cardiovascular risk analysed by mean HRV
Type 2 diabetes mellitus is an insidious disease that is increasingly present in geriatric population [1]. The greatest difficulty is represented by glycaemic control in geriatric patients often not very compliant with diet therapy and drug therapy. A new insulin glargine 300 units/ml formulation seems im- prove patient compliance due to the lower volume of insulin to be injected and improved glycaemic control over 24 hours. The HRV signal, derived from digital electrocardiographic recording, is the simplest and most imme- diate analysis that consists in calculating some temporal parameters [2]. HRV is a simple statistics derived from beat-beat intervals of sinus origin expressed as units of time in milliseconds. Data in the literature indicate that a decrease in HRV, measured with time domain analysis, denotes a worse prognosis and/or an increased risk of mortality in patients with heart disease, especially in the elderly ones
High luminosity interaction region design for collisions with detector solenoid
An innovatory interaction region has been recently conceived and realized on
the Frascati DA{\Phi}NE lepton collider. The concept of tight focusing and
small crossing angle adopted until now to achieve high luminosity in multibunch
collisions has evolved towards enhanced beam focusing at the interaction point
with large horizontal crossing angle, thanks to a new compensation mechanism
for the beam-beam resonances. The novel configuration has been tested with a
small detector without solenoidal field yielding a remarkable improvement in
terms of peak as well as integrated luminosity. The high luminosity interaction
region has now been modified to host a large detector with a strong solenoidal
field which significantly perturbs the beam optics introducing new design
challenges in terms of interaction region optics design, beam transverse
coupling control and beam stay clear requirementsComment: 3 pages, 4 figures, presented to the IPAC10 conferenc
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