3,116 research outputs found
Mesoscopic rings with Spin-Orbit interactions
A didactic description of charge and spin equilibrium currents on mesoscopic
rings in the presence of Spin-Orbit interaction is presented. Emphasis is made
on the non trivial construction of the correct Hamiltonian in polar
coordinates, the calculation of eigenvalues and eigenfunctions and the
symmetries of the ground state properties. Spin currents are derived following
an intuitive definition and then a more thorough derivation is built upon the
canonical Lagrangian formulation that emphasizes the SU(2) gauge structure of
the transport problem of spin 1/2 fermions in spin-orbit active media. The
quantization conditions that follow from the constraint of single-valued Pauli
spinors are also discussed. The targeted students are those of a graduate
Condensed Matter Physics course
Smoothened receptor signaling regulates the developmental shift of GABA polarity in rat somatosensory cortex.
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordSonic Hedgehog (Shh) and its patched-smoothened receptor complex control a variety of functions in the developing central nervous system such as neural cell proliferation and differentiation. Recently, Shh signaling components have been found to be expressed at the synaptic level in the postnatal brain, suggesting a potential role in the regulation of synaptic transmission. Using in utero electroporation of constitutively active and negative-phenotype forms of the Shh signal transducer smoothened (Smo), we studied the role of Smo signaling in the development and maturation of GABAergic transmission in the somatosensory cortex. Our results show that enhancing Smo activity during development accelerates the shift from depolarizing to hyperpolarizing GABA in dependence on functional expression of potassium-chloride cotransporter type 2 (KCC2). On the other hand, blocking Smo activity maintains GABA response in a depolarizing state in mature cortical neurons resulting in altered chloride homeostasis and increased seizure susceptibility. This study reveals an unexpected function of Smo signaling on the regulation of chloride homeostasis through the control of KCC2 cell surface stability and on the timing of the GABA inhibitory/excitatory shift in brain maturation
Perfect spin filtering device through a Mach Zehnder interferometer in GaAs/AlGaAs electron gas
Spin filtering through quantum spin interference is addressed exactly, in two
dimensions, in a medium that has both Rashba and Dresselhaus spin-orbit
couplings and an applied external magnetic field. The problem is addressed from
the fully non-Abelian Gauge formulation. We propose an experimentally feasible
electronic Mach Zehnder Interferometer and solve for the perfect spin filtering
conditions. We find two broad solutions, one where filtering is achieved in the
original incoming basis, that is purely a non-Abelian solution, and the other
where one needs a tilted axis to observe the polarized output spinor. The
latter solution is well approximated by an Abelianized approximation. Both
solutions apply for arbitrary incoming polarization, and are only limited by
the randomness of the incoming spinor state.Comment: published version, one figure adde
Gauge symmetry breaking and topological quantization for the Pauli Hamiltonian
We discuss the Pauli Hamiltonian within a gauge theory
interpretation, where the gauge symmetry is broken. This interpretation carries
directly over to the structural inversion asymmetric spin-orbit interactions in
semiconductors and offers new insight into the problem of spin currents in the
condensed matter environment. The central results is that symmetry breaking
leads to zero spin conductivity in contrast to predictions of Gauge symmetric
treatments. Computing the translation operator commutation relations comprising
the simplest possible structural inversion asymmetry due to an external
electric field, we derive a new condition for orbit quantization. The relation
between the topological nature of this effect is consistent with our
non-Abelian gauge symmetry breaking scenario.Comment: 7 pages, 1 figur
Overview of telematics-based prognostics and health management systems for commercial vehicles
Prognostics and Health Management/Monitoring (PHM) are methods to assess the health condition and reliability of systems for the purpose of maximising operational reliability and safety. Recently, PHM systems are emerging in the automotive industry. In the commercial vehicle sector, reducing the maintenance cost and downtime while also improving the reliability of vehicle components can have a major impact on fleet performance and hence business competitiveness. Nowadays, telematics and GPS are used mainly for fleet tracking and diagnostics purposes. Increased numbers of sensors installed on commercial vehicles, advancement of data analytics and computational intelligence methods, increased capabilities for on-board data processing as well as in the cloud, are creating an opportunity for PHM systems to be deployed on commercial vehicles and hence improve the overall operational efficiency
Driven diffusive system with non-local perturbations
We investigate the impact of non-local perturbations on driven diffusive
systems. Two different problems are considered here. In one case, we introduce
a non-local particle conservation along the direction of the drive and in
another case, we incorporate a long-range temporal correlation in the noise
present in the equation of motion. The effect of these perturbations on the
anisotropy exponent or on the scaling of the two-point correlation function is
studied using renormalization group analysis.Comment: 11 pages, 2 figure
- …