Theory of the tunneling spectroscopy of ferromagnetic superconductors

We study tunneling conductance in normal metal / insulator / ferromagnetic superconductor junctions. The tunneling spectra show a clear difference between spin-singlet s-wave pairing, spin-triplet opposite spin pairing and spin-triplet equal spin pairing: These pairings exhibit, respectively, gap struture, double peak structure and zero bias peak in the spectra. The obtained result may serve as a tool for determining the pairing symmetry of ferromagnetic superconductors.Comment: 4 pages, 2 figure

Production of a T cell hybridoma that expresses the T cell receptor gamma/delta heterodimer.

We have produced a T cell hybridoma line by fusion of an IL-2-dependent, long-term T cell receptor (TCR) gamma/delta+ Thy-1+, bone marrow-derived, dendritic epidermal cell line to the BW5147 tumor line. The resultant hybridoma was rapidly growing, lymphokine independent, and expressed T3 in association with the TCR gamma/delta heterodimer. Several subclones of the hybridoma line produced easily detectable levels of IL-2 after stimulation by anti-T3 or Con A. The availability of these cloned cell lines should greatly facilitate further functional, biochemical, and molecular studies of the TCR delta chain

A-VIP: Anonymous Verification and Inference of Positions in Vehicular Networks

MiniconferenceInternational audienceKnowledge of the location of vehicles and tracking of the routes they follow are a requirement for a number of applications, including e-tolling and liability attribution in case of accidents. However, public disclosure of the identity and position of drivers jeopardizes user privacy, and securing the tracking through asymmetric cryptography may have an exceedingly high computational cost. Additionally, there is currently no way an authority can verify the correctness of the position information provided by a potentially misbehaving car. In this paper, we address all of the issues above by introducing A-VIP, a lightweight framework for privacy preserving and tracking of vehicles. A-VIP leverages anonymous position beacons from vehicles, and the cooperation of nearby cars collecting and reporting the beacons they hear. Such information allows an authority to verify the locations announced by vehicles, or to infer the actual ones if needed. We assess the effectiveness of A-VIP through both realistic simulation and testbed implementation results, analyzing also its resilience to adversarial attacks

Efeito da arcelina na biologia de Zabrotes subfasciatus (Bohemann, 1833) (Coleoptera-bruchidae).

A proteina arcelina constitui-se em alternativa promissora para o controle de Zabrotes subfasciatus, importante praga do feijao (Phaseolus vulgaris) armazenado. Nas progenies de dez casais, avaliou-se o efeito de quatro variantes de arcelina (Arc1, Arc2, Arc3, Arc4), comparativamente aos controles suscetiveis 'Porrillo 70' e 'Goiano Precoce'. Os parametros avaliados foram: oviposicao, insetos emergidos, periodo ovo-adulto, razao sexual, proporcao e longevidade de machos e femeas. O menor numero medio de ovos foi observado em Arc1 (20,1) e Arc3 (28,2), seguidos por Arc4 (35,7), Arc2 (36,0), 'Porrillo 70' (44,2) e 'Goiano Precoce' (50,1). Em todos os tratamentos a postura foi iniciada no primeiro dia de vida sendo que o periodo de oviposicao mais longo foi observado e, 'Goiano Precoce' (12 dias) e o menor em Arc1, Arc3 e Arc4 (7 dias). Na oviposicao, do segundo ate o quinto dia, detectou-se a maior emergencia. O menor numero medio de insetos emergidos ocorreu em Arc1 e Arc2, seguidos por Arc3, Arc4, 'Porrillo 70' e 'Goiano Precoce', respectivamente, com 3,3;8,1; 18,2; 22,1; 27,5 e 33,9 insetos. Nas linhagens contendo arcelina, o periodo ovo-adulto foi alongado, sendo de 43,7; 36,5; 37,5; 36,6; 32,4 e 31,1 dias, respectivamente, para Arc1, Arc2, Arc3, Arc4, 'Porrillo 70' e 'Goiano Precoce'. A menor longevidade dos adultos foi observada em Arc1 e, com excecao dessa linhagem, foi maior nos machos que nas femeas. A razao sexual (0,52-0,54), e a proporcao entre machos e femeas (1:1,08-1:1,20), nao foi afetada pela (...

Charge transport in two dimensional electron gas/superconductor junctions with Rashba spin-orbit coupling

We have studied the tunneling conductance in two dimensional electron gas / insulator / superconductor junctions in the presence of Rashba spin-orbit coupling (RSOC). It is found that for low insulating barrier the tunneling conductance is suppressed by the RSOC while for high insulating barrier it is almost independent of the RSOC. We also find the reentrant behavior of the conductance at zero voltage as a function of RSOC for intermediate insulating barrier strength. The results are essentially different from those predicted in ferromagnet / superconductor junctions. The present derivation of the conductance is applicable to arbitrary velocity operator with off-diagonal components.Comment: 8 pages, 6 figure

Theory of Josephson effect in chiral p-wave superconductor / diffusive normal metal / chiral p-wave superconductor junctions

We study the Josephson effect between chiral p-wave superconductor / diffusive normal metal (DN) / chiral p-wave superconductor (CP/DN/CP) junctions using quasiclassical Green's function formalism with proper boundary conditions. The px+ipy-wave symmetry of superconducting order parameter is chosen which is believed to be a pairing state in Sr2RuO4. It is shown that the Cooper pairs induced in DN have an odd-frequency spin-triplet s-wave symmetry, where pair amplitude is an odd function of Matsubara frequency. Despite the peculiar symmetry properties of the Cooper pairs, the behavior of the Josephson current is rather conventional. We have found that the current phase relation is almost sinusoidal and the Josephson current is proportional to exp(-L/xi), where xi is the coherence length of the Cooper pair in DN and L is the length of DN. The Josephson current between CP / diffusive ferromagnet metal (DF) / CP junctions is also calculated. It is shown that the 0-pi transition can be realized by varying temperature or junction length L similar to the case of conventional s-wave junctions. These results may serve as a guide to study superconducting state of Sr2RuO4.Comment: 9 pages, 9 figure

Crossover of superconducting properties and kinetic-energy gain in two-dimensional Hubbard model

Superconductivity in the Hubbard model on a square lattice near half filling is studied using an optimization (or correlated) variational Monte Carlo method. Second-order processes of the strong-coupling expansion are considered in the wave functions beyond the Gutzwiller factor. Superconductivity of d_x^2-y^2-wave is widely stable, and exhibits a crossover around U=U_co\sim 12t from a BCS type to a new type. For U\gsim U_co (U\lsim U_co), the energy gain in the superconducting state is derived from the kinetic (potential) energy. Condensation energy is large and \propto exp(-t/J) [tiny] on the strong [weak] coupling side of U_co. Cuprates belong to the strong-coupling regime.Comment: 4 pages, 6 figure

Mott Transitions and d-wave Superconductivity in Half-Filled-Band Hubbard Model on Square Lattice with Geometric Frustration

Mechanisms of Mott transitions and dx2-y2-wave superconductivity (SC) are studied in the half-filled-band Hubbard model on square lattices with a diagonal hopping term (t'), using an optimization (or correlated) variational Monte Carlo method. In the trial wave functions, a doublon-holon binding effect is introduced in addition to the onsite Gutzwiller projection. We mainly treat a d-wave singlet state and a projected Fermi sea. In both wave functions, first-order Mott transitions without direct relevance to magnetic orders take place at U=Uc approximately of the bandwidth for arbitrary t'/t. These transitions originate in the binding or unbinding of a doublon to a holon. d-wave SC appears in a narrow range immediately below Uc. The robust d-wave superconducting correlation are necessarily accompanied by enhanced antiferromagnetic correlation; the strength of SC becomes weak, as t'/t increases.Comment: 18 pages, 30 figure