We have measured the flux flow Hall effect in the superconducting state of various high-T c superconductors (HTSC) from the underdoped to the overdoped regime. We show that the Hall sign is universal and is determined by the doping level; the sign is electronlike in the underdoped regime and holelike in the overdoped regime. This tendency contradicts the prediction of the time dependent Ginzburg-Landau equation based on the s-wave weak coupling theory, suggesting that such a theory fails to evaluate the Hall force acting on the vortices in HTSC. This discrepancy may be attributed to the novel electronic structure of the vortex in HTSC. [S0031-9007(98)05831-1] PACS numbers: 74.25.Fy, 74.25.Jb, 74.60.GeThe vortex motion in the superfluid electrons has presented a persistent problem in the superconducting state of type II superconductors. Knowledge of the Hall effect enables us to obtain clear and important information on this problem. One of the most puzzling and controversial phenomena is the sign change that has been observed in the Hall effect in the superconducting state in most high-T c superconductors (HTSC) and some conventional superconductors [1]. The Hall sign is determined by the topology of the Fermi surface in the normal state, while it is determined by the vortex motion in the superconducting state. The classical theories of vortex motion, the Bardeen-Stephen [2] and Nozieres-Vinen [3] models, predict that the superconducting and normal states will have the same Hall sign, and thus cannot explain this anomaly. Recent experiments have ruled out the possibility that some form of pinning induces the sign reversal [4,5]. Moreover, the occurrence of the sign reversal in one-unitcell-thick ultrathin YBa 2 Cu 3 O 72d film demonstrates that the Hall anomaly occurs in a two-dimensional CuO 2 plane [6]. Several attempts to understand the Hall anomaly have been undertaken, but the microscopic origin of this phenomenon remains a controversial and vexing problem that demonstrates explicitly our incomplete knowledge of vortex dynamics.A recent phenomenological theory based on the time dependent Ginzburg-Landau (TDGL) equation has been shown to be quite successful in describing the Hall effect in the superconducting state [7,8]. According to the TDGL theory, the vortex Hall conductivity s V xy arising from the hydrodynamic contribution plays an important role in determining the Hall sign at low fields. The Hall sign reversal occurs when s V xy has a sign opposite that of the normal state Hall effect. In the framework within the BCS theory, several authors have calculated s V xy and emphasized the importance of the electronic structure of the materials for understanding the Hall effect. Fukuyama, Ebisawa, and Tsuzuki (FET) [9] have derived the TDGL equation from the microscopic BCS theory and found that s V xy appears as a result of the electronhole asymmetry, which is quantified by ≠N͑m͒͞≠mj m´F , where N(m) is the density of states, m is the chemical potential, and´F is the Fermi energy. Recently, Aronov, Hikami, a...

The authors successfully treated patients with writer's cramp by thalamic DBS. Insofar as they are aware, this is the first series in which writer's cramp has been treated with DBS. Thalamic stimulation appears to be a safe and valuable therapeutic option for writer's cramp.

Aims:  The present study was conducted to screen for psychrophilic yeasts that are able to degrade pectin compounds at low temperature, and to examine the cold‐active pectinolytic enzymes produced by the isolated psychrophilic yeasts. Methods and Results:  Psychrophilic yeasts, which grow on pectin as a sole carbon source, pectinolytic–psychrophilic yeast (PPY) strains PPY‐3, 4, 5 and 6, were isolated from soil from Abashiri (Hokkaido, Japan). The sequences of 28S rDNA D1/D2 of strains PPY‐3 and 4 indicated a taxonomic affiliation to Cryptococcus cylindricus and Mrakia frigida, respectively, strains PPY‐5 and 6 belonged to Cystofilobasidium capitatum. The isolated strains were able to grow on pectin at below 5°C, and showed the activities of several cold‐active pectinolytic enzymes. Conclusion:  The findings of this study indicate the possibility that the isolated strains produce novel pectinolytic enzymes that are able to degrade pectin compounds at low temperature. Significance and Impact of the Study:  It is possible that the cold‐active pectinolytic enzymes from the isolated strains can be applied to the food industry, e.g. the clarification of fruit juice below 5°C.

No abstract

An antifungal metabolite, oosporein, was isolated from the culture of Verticillium psalliotae that produced the antagonistic effects on Phytophthora infestans. Oosporein exhibited a significant growth-inhibitory effect on P. infestans in comparison with other phytopathogenic fungi.