A peak in the resistance versus temperature measurements, just above
T
c, has been observed in Nb/CuMn multilayers with a regular array of holes. The peak is present in zero magnetic field and its ...height becomes smaller as the perpendicular field is increased. The presence of the peak could be related to the nonhomogeneity of the sample consistently giving an explanation for the upward curvature observed in the
H
c2 versus temperature curve.
Transport properties of Nb/CuMn multilayers with a regular array of antidots have been measured at different temperatures in the presence of external perpendicular magnetic fields. Two series of ...samples, which differ for the Mn percentage, for the diameter, and for distance of the antidots have been analyzed. In both the series, hysteresis in current–voltage characteristics has been observed, which disappears when approaching the upper critical magnetic field. We have related the onset of this hysteresis to the presence of an irreversibility line in the
H–
T plane, due to the quantum melting of the vortex lattice.
We present a detailed study of the critical current density of YBa
2Cu
3O
7−
δ
thin films grown by pulsed laser deposition. Among the salient features are the total absence of any traits ...characteristic for pinning by extended linear defects, and an unexpected increase of the critical current density with film thickness. It turns out that critical current the dependence of critical current density on thickness is correlated with the field dependence of the same quantity; thicknesses of the both are very well described by extending to finite film thickness the Ovchinnikov–Ivlev theory of strong pinning Phys. Rev. B 43 (1991) 8024.
The efficacy of anti-herpetic drugs in decreasing HIV disease progression has not been clarified. We studied a cohort of 126 HIV-positive individuals with known date of seroconversion who were ...HSV-2-seropositive to determine if progression to AIDS was influenced by treatment with acyclovir. In the multivariate analysis, being homosexual and low CD4 count were associated with a faster progression to AIDS, whereas treatment with acyclovir showed a 37.0% protective effect compared to those who did not receive it when antiretroviral treatment was not included in the model. When including antiretroviral therapy, the protective effect of acyclovir decreased to 9.0% and that of antiretroviral therapy was 43.0% for monotherapy and 36.0% for double therapy, suggesting that most of the protective effect of acyclovir in the previous model was due to antiretroviral therapy. In conclusion, treatment with acyclovir does not seem to prolong significantly survival to AIDS among HIV-positive individuals who are HSV-2-infected.
Transport properties of Nb/CuMn multilayers with a regular array of antidots have been measured at different temperatures in the presence of external perpendicular magnetic fields. Two series of ...samples, which differ for the Mn percentage, for the diameter, and for distance of the antidots have been analyzed. In both the series, hysteresis in current-voltage characteristics has been observed, which disappears when approaching the upper critical magnetic field. We have related the onset of this hysteresis to the presence of an irreversibility line in the H-T plane, due to the quantum melting of the vortex lattice.
We present a detailed study of the critical current density of YBa sub(2)Cu sub(3 )O sub(7- delta ) thin films grown by pulsed laser deposition. Among the salient features are the total absence of ...any traits characteristic for pinning by extended linear defects, and an unexpected increase of the critical current density with film thickness. It turns out that critical current the dependence of critical current density on thickness is correlated with the field dependence of the same quantity; thicknesses of the both are very well described by extending to finite film thickness the Ovchinnikov-Ivlev theory of strong pinning Phys. Rev. B 43 (1991) 8024. copyright 2001 Elsevier Science B.V. All rights reserved.
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