Quasiclassical approach to the spin-Hall effect in the two-dimensional electron gas

We study the spin-charge coupled transport in a two-dimensional electron system using the method of quasiclassical ($\xi$-integrated) Green's functions. In particular we derive the Eilenberger equation in the presence of a generic spin-orbit field. The method allows us to study spin and charge transport from ballistic to diffusive regimes and continuity equations for spin and charge are automatically incorporated. In the clean limit we establish the connection between the spin-Hall conductivity and the Berry phase in momentum space. For finite systems we solve the Eilenberger equation numerically for the special case of the Rashba spin-orbit coupling and a two-terminal geometry. In particular, we calculate explicitly the spin-Hall induced spin polarization in the corners, predicted by Mishchenko et al. [13]. Furthermore we find universal spin currents in the short-time dynamics after switching on the voltage across the sample, and calculate the corresponding spin-Hall polarization at the edges. Where available, we find perfect agreement with analytical results.Comment: 9 pages, 6 figure

Effects of the electron-phonon coupling near and within the insulating Mott phase

The role of the electron-phonon interaction in the Holstein-Hubbard model is investigated in the metallic phase close to the Mott transition and in the insulating Mott phase. The model is studied by means of a variational slave boson technique. At half-filling, mean-field static quantities are in good agreement with the results obtained by numerical techniques. By taking into account gaussian fluctuations, an analytic expression of the spectral density is derived in the Mott insulating phase showing that an increase of the electron-phonon coupling leads to a sensitive reduction of the Mott gap through a reduced effective repulsion. The relation of the results with recent experimental observations in strongly correlated systems is discussed.Comment: 4 pages, 4 figure

A model for trustworthy orchestration in the internet of things

Embedded systems such as Cyber-Physical Systems (CPS) are typically designed as a network of multiple interacting elements with physical input (or sensors) and output (or actuators). One aspect of interest of open systems is fidelity, or the compliance between physical figures of interest and their internal representation. High fidelity is defined as a stable mapping between actions in the physical domain and intended or expected values in the system domain and deviations from fidelity are quantifiable over time by some appropriate informative variable. In this paper, we provide a model for designing such systems based on a framework for trustworthiness monitoring and we provide a Jason implementation to evaluate the feasibility of our approach. In particular, we build a bridge between a standard publish/subscribe framework for CPS called MQTT and Jason to enable automatic reasoning about trustworthines

Current-induced spin polarization in InGaAs and GaAs epilayers with varying doping densities

The current-induced spin polarization and momentum-dependent spin-orbit field were measured in In$_{x}$Ga$_{1-x}$As epilayers with varying indium concentrations and silicon doping densities. Samples with higher indium concentrations and carrier concentrations and lower mobilities were found to have larger electrical spin generation efficiencies. Furthermore, current-induced spin polarization was detected in GaAs epilayers despite the absence of measurable spin-orbit fields, indicating that the extrinsic contributions to the spin polarization mechanism must be considered. Theoretical calculations based on a model that includes extrinsic contributions to the spin dephasing and the spin Hall effect, in addition to the intrinsic Rashba and Dresselhaus spin-orbit coupling, are found to qualitatively agree with the experimental results.Comment: 16 pages, 8 figure

Trade effects of geographical indication policy: The EU case

Using a new detailed dataset on country-product information on European Union (EU) Geographical Indications (GIs), we study the impact of this food quality policy on trade margins over the 1996–2014 period. We consider the effect of GIs on both intra- and extra-EU trade margins (extensive and intensive), as well as on export (and import) unit values. Our main results show that GIs affect trade flows differently depending on whether GIs are produced by the exporter or importer country. The presence of GIs in the exporter country systematically exerts a positive trade effect on both the extensive and intensive trade margin. When registered only in the importer country, GIs seem to act weakly as a trade-reducing measure, at least at the intensive trade margin. In addition, GIs positively affect export prices, consistent with the idea that GI products are perceived by consumers as higher quality goods. Importantly, extra-EU trade margins react similarly to those on intra-EU trade. These results have clear and interesting implications concerning the EU strategy of promoting the protection of GIs worldwide

Neuropilin-1 Controls Endothelial Homeostasis by Regulating Mitochondrial Function and Iron-Dependent Oxidative Stress.

The transmembrane protein neuropilin-1 (NRP1) promotes vascular endothelial growth factor (VEGF) and extracellular matrix signaling in endothelial cells (ECs). Although it is established that NRP1 is essential for angiogenesis, little is known about its role in EC homeostasis. Here, we report that NRP1 promotes mitochondrial function in ECs by preventing iron accumulation and iron-induced oxidative stress through a VEGF-independent mechanism in non-angiogenic ECs. Furthermore, NRP1-deficient ECs have reduced growth and show the hallmarks of cellular senescence. We show that a subcellular pool of NRP1 localizes in mitochondria and interacts with the mitochondrial transporter ATP-binding cassette B8 (ABCB8). NRP1 loss reduces ABCB8 levels, resulting in iron accumulation, iron-induced mitochondrial superoxide production, and iron-dependent EC senescence. Treatment of NRP1-deficient ECs with the mitochondria-targeted antioxidant compound mitoTEMPO or with the iron chelator deferoxamine restores mitochondrial activity, inhibits superoxide production, and protects from cellular senescence. This finding identifies an unexpected role of NRP1 in EC homeostasis

Synchrotron oscillation damping due to beam-beam collisions

In DA{\Phi}NE, the Frascati e+/e- collider, the crab waist collision scheme has been successfully implemented in 2008 and 2009. During the collision operations for Siddharta experiment, an unusual synchrotron damping effect has been observed. Indeed, with the longitudinal feedback switched off, the positron beam becomes unstable with beam currents in the order of 200-300 mA. The longitudinal instability is damped by bringing the positron beam in collision with a high current electron beam (~2A). Besides, we have observed a shift of \approx 600Hz in the residual synchrotron sidebands. Precise measurements have been performed by using both a commercial spectrum analyzer and the diagnostics capabilities of the DA{\Phi}NE longitudinal bunch-by-bunch feedback. This damping effect has been observed in DA{\Phi}NE for the first time during collisions with the crab waist scheme. Our explanation is that beam collisions with a large crossing angle produce a longitudinal tune shift and a longitudinal tune spread, providing Landau damping of synchrotron oscillations.Comment: 3 pages, 5 figures, talk presented to IPAC'10 - Kyoto - May 24-28 201

Non-Abelian gauge fields in the gradient expansion: generalized Boltzmann and Eilenberger equations

We present a microscopic derivation of the generalized Boltzmann and Eilenberger equations in the presence of non-Abelian gauges, for the case of a non-relativistic disordered Fermi gas. A unified and symmetric treatment of the charge $[U(1)]$ and spin $[SU(2)]$ degrees of freedom is achieved. Within this framework, just as the $U(1)$ Lorentz force generates the Hall effect, so does its $SU(2)$ counterpart give rise to the spin Hall effect. Considering elastic and spin-independent disorder we obtain diffusion equations for charge and spin densities and show how the interplay between an in-plane magnetic field and a time dependent Rashba term generates in-plane charge currents.Comment: 11 pages, 1 figure; some corrections and updated/extended reference

Multiparametric advanced research tool for meteo satellites data interfacing with space observation of ultra high energy cosmic rays

To approach the study of the cosmic rays in the energy range E > 1020 eV, the upper end of the spectrum observed to date, with a large statistical significance (103 events/year), and hence address the solution of several astrophysical and cosmological problems related to their existence and behaviour, a new generation of experiments will probably have to be conceived and realised. They will be based on the observation and measurements of cosmic rays from space. The extremely low rate of these events (∼ 1 event/(century × km2 × sr)) imposes a very large effective area to be monitored, of the order of 105 km2, as an observational requirement to meet the target statistics. The Extreme Universe Space Observatory (EUSO)mission has been proposed as the precursor of this new generation of experiments. Its approach consists in fact in looking downwards to the Earth atmosphere by means of a large field-of-view telescope accommodated aboard an orbiting satellite. The fluorescence strike produced by a cosmic ray through the atmosphere will be recorded by the detector, which will reconstruct the kinematical and dynamical features of the primary cosmic ray. The atmosphere acts therefore as an active target for the detectable event. A strategic tool for the success of EUSO as well as for all the experiments of its category will be a correct and detailed atmospheric sounding system, in order to monitor the atmospheric parameters within the field-of-view of the telescope. Beside an on-board measurement by means of dedicated devices such an infrared camera (IR)and possibly a LIDAR (LIght Detection And Ranging)coupled to the main instrument, the Atmosphere Sounding will take advantage from the continuous observation of the atmospheric parameters given by the orbiting meteorological satellites. Their databases have thus to be interfaced to the experimental data and used picking-up the relevant data according to the space and time coordinates corresponding to each triggered event. The present work outlines a software module (MARVIN-Multiparametric Advanced Research tool for Visualisation In the Network) able to build-up such an interface, and shows a preliminary implementation of it, using a sample of existing satellites and ISCCP meteorological data collection. It has been developed during the phase A study of the EUSO mission but is general enough to be adapted to different missions observing the Earth atmosphere from space