Off-equilibrium corrections to energy and conserved charge densities in the relativistic fluid in heavy-ion collisions

Dissipative processes in relativistic fluids are known to be important in the analyses of the hot QCD matter created in high-energy heavy-ion collisions. In this work, I consider dissipative corrections to energy and conserved charge densities, which are conventionally assumed to be vanishing but could be finite. Causal dissipative hydrodynamics is formulated in the presence of those dissipative currents. The relation between hydrodynamic stability and transport coefficients is discussed. I then study their phenomenological consequences on the observables of heavy-ion collisions in numerical simulations. It is shown that particle spectra and elliptic flow can be visibly modified.Comment: 10 pages, 5 figures; title changed, references added, conclusions unchange

Room temperature Giant Spin-dependent Photoconductivity in dilute nitride semiconductors

By combining optical spin injection techniques with transport spectroscopy tools, we demonstrate a spin-photodetector allowing for the electrical measurement and active filtering of conduction band electron spin at room temperature in a non-magnetic GaAsN semiconductor structure. By switching the polarization of the incident light from linear to circular, we observe a Giant Spin-dependent Photoconductivity (GSP) reaching up to 40 % without the need of an external magnetic field. We show that the GSP is due to a very efficient spin filtering effect of conduction band electrons on Nitrogen-induced Ga self-interstitial deep paramagnetic centers.Comment: 4 pages, 3 figure

Spin and recombination dynamics of excitons and free electrons in p-type GaAs : effect of carrier density

Carrier and spin recombination are investigated in p-type GaAs of acceptor concentration NA = 1.5 x 10^(17) cm^(-3) using time-resolved photoluminescence spectroscopy at 15 K. At low pho- tocarrier concentration, acceptors are mostly neutral and photoelectrons can either recombine with holes bound to acceptors (e-A0 line) or form excitons which are mostly trapped on neutral acceptors forming the (A0X) complex. It is found that the spin lifetime is shorter for electrons that recombine through the e-A0 transition due to spin relaxation generated by the exchange scattering of free electrons with either trapped or free holes, whereas spin flip processes are less likely to occur once the electron forms with a free hole an exciton bound to a neutral acceptor. An increase of exci- tation power induces a cross-over to a regime where the bimolecular band-to-band (b-b) emission becomes more favorable due to screening of the electron-hole Coulomb interaction and ionization of excitonic complexes and free excitons. Then, the formation of excitons is no longer possible, the carrier recombination lifetime increases and the spin lifetime is found to decrease dramatically with concentration due to fast spin relaxation with free photoholes. In this high density regime, both the electrons that recombine through the e-A0 transition and through the b-b transition have the same spin relaxation time.Comment: 4 pages, 5 figure

In situ relationships between microbiota and potential pathobiota in Arabidopsis thaliana.

A current challenge in microbial pathogenesis is to identify biological control agents that may prevent and/or limit host invasion by microbial pathogens. In natura, hosts are often infected by multiple pathogens. However, most of the current studies have been performed under laboratory controlled conditions and by taking into account the interaction between a single commensal species and a single pathogenic species. The next step is therefore to explore the relationships between host-microbial communities (microbiota) and microbial members with potential pathogenic behavior (pathobiota) in a realistic ecological context. In the present study, we investigated such relationships within root-associated and leaf-associated bacterial communities of 163 ecologically contrasted Arabidopsis thaliana populations sampled across two seasons in southwest of France. In agreement with the theory of the invasion paradox, we observed a significant humped-back relationship between microbiota and pathobiota α-diversity that was robust between both seasons and plant organs. In most populations, we also observed a strong dynamics of microbiota composition between seasons. Accordingly, the potential pathobiota composition was explained by combinations of season-specific microbiota operational taxonomic units. This result suggests that the potential biomarkers controlling pathogen\u27s invasion are highly dynamic

Production of negative ions on graphite surface in H₂/D₂ plasmas: experiments and SRIM calculations

In previous works, surface-produced negative-ion distribution-functions have been measured in H2 and D2 plasmas using graphite surfaces (highly oriented pyrolitic graphite). In the present paper, we use the srim software to interpret the measured negative-ion distribution-functions. For this purpose, the distribution-functions of backscattered and sputtered atoms arising due to the impact of hydrogen ions on a-CH and a-CD surfaces are calculated. The srim calculations confirm the experimental deduction that backscattering and sputtering are the mechanisms of the origin of the creation of negative ions at the surface. It is shown that the srim calculations compare well with the experiments regarding the maximum energy of the negative ions and reproduce the experimentally observed isotopic effect. A discrepancy between calculations and measurements is found concerning the yields for backscattering and sputtering. An explanation is proposed based on a study of the emitted-particle angular-distributions as calculated by srim

Electron-Shading Characterization in a HDP Contact Etching Process Using a Patterned CHARM Wafer

In this work, a CHARM-2 wafer with high aspect ratio resist patterns has been used to quantitatively I. Introduction To understand the origin of plasma-induced damage, useful plasma parameters such as floating potentials and J-V characteristics can be measured using the non-invasive CHARM method To study this effect, we have designed different resist patterns on a 200 mm CHARM™-2 wafer with an e-beam lithography. This allows to obtain realistic variable aspect ratio as high as 4, contrary to previous studie