Josephson effect in two-band superconductors

We study theoretically the Josephson effect between two time-reversal two-band superconductors, where we assume the equal-time spin-singlet $s$-wave pair potential in each conduction band. %as well as the band asymmetry and the band hybridization in the normal state. The superconducting phase at the first band $\varphi_1$ and that at the second band $\varphi_2$ characterize a two-band superconducting state. We consider a Josephson junction where an insulating barrier separates two such two-band superconductors. By applying the tunnel Hamiltonian description, the Josephson current is calculated in terms of the anomalous Green's function on either side of the junction. We find that the Josephson current consists of three components which depend on three types of phase differences across the junction: the phase difference at the first band $\delta\varphi_1$, the phase difference at the second band $\delta\varphi_2$, and the difference at the center-of-mass phase $\delta(\varphi_1+\varphi_2)/2$. A Cooper pairs generated by the band hybridization carries the last current component. In some cases, the current-phase relationship deviates from the sinusoidal function as a result of time-reversal symmetry breaking down.Comment: 6 page, 2 figure

Galactic-Center Hyper-Shell Model for the North Polar Spurs

The bipolar-hyper shell (BHS) model for the North Polar Spurs (NPS-E, -W, and Loop I) and counter southern spurs (SPS-E and -W) is revisited based on numerical hydrodynamical simulations. Propagations of shock waves produced by energetic explosive events in the Galactic Center are examined. Distributions of soft X-ray brightness on the sky at 0.25, 0.7, and 1.5 keV in a +/-50 deg x +/-50 deg region around the Galactic Center are modeled by thermal emission from high-temperature plasma in the shock-compressed shell considering shadowing by the interstellar HI and H2 gases. The result is compared with the ROSAT wide field X-ray images in R2, 4 and 6 bands. The NPS and southern spurs are well reproduced by the simulation as shadowed dumbbell-shaped shock waves. We discuss the origin and energetics of the event in relation to the starburst and/or AGN activities in the Galactic Center. [ High resolution pdf is available at http://www.ioa.s.u-tokyo.ac.jp/~sofue/htdocs/2016bhs/ ]Comment: 13 pages, 20 figures; To appear in MNRA

Why do starless cores appear more flattened than protostellar cores?

We evaluate the intrinsic three dimensional shapes of molecular cores, by analysing their projected shapes. We use the recent catalogue of molecular line observations of Jijina et al. and model the data by the method originally devised for elliptical galaxies. Our analysis broadly supports the conclusion of Jones et al. that molecular cores are better represented by triaxial intrinsic shapes (ellipsoids) than biaxial intrinsic shapes (spheroids). However, we find that the best fit to all of the data is obtained with more extreme axial ratios ($1:0.8:0.4$) than those derived by Jones et al. More surprisingly, we find that starless cores have more extreme axial ratios than protostellar cores -- starless cores appear more `flattened'. This is the opposite of what would be expected from modeling the freefall collapse of triaxial ellipsoids. The collapse of starless cores would be expected to proceed most swiftly along the shortest axis - as has been predicted by every modeller since Zel'dovich - which should produce more flattened cores around protostars, the opposite of what is seen.Comment: 7 pages, 3 figure

Application of the Limit Cycle Model to Star Formation Histories in Spiral Galaxies: Variation among Morphological Types

We propose a limit-cycle scenario of star formation history for any morphological type of spiral galaxies. It is known observationally that the early-type spiral sample has a wider range of the present star formation rate (SFR) than the late-type sample. This tendency is understood in the framework of the limit-cycle model of the interstellar medium (ISM), in which the SFR cyclically changes in accordance with the temporal variation of the mass fraction of the three ISM components. When the limit-cycle model of the ISM is applied, the amplitude of variation of the SFR is expected to change with the supernova (SN) rate. Observational evidence indicates that the early-type spiral galaxies show smaller rates of present SN than late-type ones. Combining this evidence with the limit-cycle model of the ISM, we predict that the early-type spiral galaxies show larger amplitudes in their SFR variation than the late-types. Indeed, this prediction is consistent with the observed wider range of the SFR in the early-type sample than in the late-type sample. Thus, in the framework of the limit-cycle model of the ISM, we are able to interpret the difference in the amplitude of SFR variation among the morphological classes of spiral galaxies.Comment: 12 pages LaTeX, to appear in A

Anomalous Surface Impedance in a Normal-metal/Superconductor Junction with a Spin-active Interface

We discuss the surface impedance (Z=R-iX) of a normal-metal/superconductor proximity structure taking into account the spin-dependent potential at the junction interface. Because of the spin mixing transport at the interface, odd-frequency spin-triplet s-wave Cooper pairs penetrate into the normal metal and cause the anomalous response to electromagnetic fields. At low temperature, the local impedance at a surface of the normal metal shows the nonmonotonic temperature dependence and the anomalous relation R>X. We also discuss a possibility of observing such anomalous impedance in experiments.Comment: 7pages, 7 figure

Avaliacao da eficiência de fungicidas no controle da cercosporiose (Cercospora zeae-maydis) na cultura do milho.

A cercosporiose do milho, causada pelo fungo Cercospora Zeae-maydis, é atualmente, no Brasil, uma das mais importantes doenças foliares dessa cultura, apresentando maior severidade de danos no sudoeste de Goiás. Este experimento foi conduzido em área de plantio direto de milho sobre milho, no município de Montividíu, ao, infectada com Cercospora zeae-maydis. O delineamento experimental foi o de blocos ao acaso, com 8 tratamentos em 4 repetições. Foi utilizado o híbrido simples Avant, de ciclo precoce. Os fungicidas foram aplicados mediante pulverizador manual pressurizado com 4 bicos pulverizadores. O volume de calda aplicado em cada parcela foi de I ,4 litros. Foram utilizados os seguintes fungicidas (g i.a.ha-1): propiconazole (100,0), propiconazole (125,0), difenoconazole (50,0), difenoconazole (75,0), azoxystrobin (50,0), azoxystrobin (75,0) e tebuconazole (200,0). Parcelas sem tratamento fungicida constituíram a testemunha. A primeira pulverização dos fungicidas foi realizada em plantas no estádio V8 (43 Dias Após o Plantio - DAP) e a segunda no estádio de pré_ emborrachamento (58 DAP). Aos 85 DAP, com plantas com espigas no estádio de grão pastoso, procedeu-se à avaliação dos sintomas foliares causados por Cercospora zeae-maydis, utilizando-se do seguinte esquema de notas: O =sem sintoma; 1 = poucas lesões nas folhas abaixo da espiga, nenhuma lesão acima; 2 = muitas lesões nas folhas abaixo da espiga, poucas lesões acima; 3 = severo desenvolvimento de lesões nas folhas abaixo da espiga, todas as folhas acima da espiga com lesões; 4 = todas as folhas com severo desenvolvimento de lesões, mas tecido verde ainda visível; 5 = todas as folhas secas e mortas. Os resultados obtidos mostram que os fungicidas propiconazole, difenoconazole, azoxystrobin e tebuconazole foram eficientes no controle da cercosporiose (Cercospora zeae-maydis) do milho e todos os tratamentos fungicida garantiram a produção de grãos de milho, sendo que a maior diferença percentual foi de 38,9% em relação à testemunha. Conclui-se que os fungicidas propiconazole, difenoconazole, azoxystrobin e tebuconazole são eficientes no controle da cercosporiose do milho causada por Cercospora zeae-maydis e que a aplicação destes produtos garantem significativamente a produção de grãos