Remarks on the Isotopic Volume Effect in Superconductors

One possible manner in which the change in isotopic volume contributes to the isotope effect in superconductors is discussed with relation to the empirical formula of Olsen et al., α=0.25+0.1φ, which represents a relation between the exponent α in T_c∞M^ and the volume dependence of the transition temperature, φ=∂ln[T_c/θ]/∂lnV・{ln(0.85θ/T_c)^. Here, the volume effect being taken into consideration, α is expressed in terms of the mass and volume effects of the Debye temperatureθand those of the phonon mediated electron-electron interaction N(0)J in the BCS relation. In addition to this, the limitations of the argument concerning the relation between the isotope effect and the volume dependence of the transition temperature are briefly examined in connection with the isotopic volume in some isotopic compounds

Nonlinear Pressure Dependence of the Superconducting Transition Temperature of Copper Sulfide CuS

The superconducting transition temperatures of copper sulfide CuS are measured as a function of hydrostatic pressure up to about 9 katm by an ice bomb technique. The superconducting transition is detected with the ac Hartshorn mutual inductance bridge. In contrast to ordinary superconductors the curve of the shift of the transition temperature with increasing pressure decrease nonlinearly with downward curvature over the whole range of applied pressures and its slope changes discontinuously at about 3.5 katm. The maximum peak of the imaginary part of the ac susceptibility vanishes under pressurs above about 1.6 katm. It is discussed that the observed unusual behaviour of the transition temperature is probably attributed to a change of the Fermi surface of the type proposed by Lifshitz

Generation of breast cancer stem cells by steroid hormones in irradiated human mammary cell lines.

Exposure to ionizing radiation was shown to result in an increased risk of breast cancer. There is strong evidence that steroid hormones influence radiosensitivity and breast cancer risk. Tumors may be initiated by a small subpopulation of cancer stem cells (CSCs). In order to assess whether the modulation of radiation-induced breast cancer risk by steroid hormones could involve CSCs, we measured by flow cytometry the proportion of CSCs in irradiated breast cancer cell lines after progesterone and estrogen treatment. Progesterone stimulated the expansion of the CSC compartment both in progesterone receptor (PR)-positive breast cancer cells and in PR-negative normal cells. In MCF10A normal epithelial PR-negative cells, progesterone-treatment and irradiation triggered cancer and stemness-associated microRNA regulations (such as the downregulation of miR-22 and miR-29c expression), which resulted in increased proportions of radiation-resistant tumor-initiating CSCs

Denudation Process of Crystalline Nappes in a Continental Collision Zone Constrained by Inversion of Fission‐Track Data and Thermokinematic Forward Modeling: An Example From Eastern Nepalese Himalaya

Thermochronological methods were applied to the Higher Himalayan Crystalline (HHC) nappe and the underlying Lesser Himalayan Sequences (LHS) to elucidate the denudation process for the middle- and upper-crust of eastern Nepal over millions of years. Thermochronological inverse modeling was undertaken for new results of fission-track (FT) age and FT length data of zircon and apatite in order to reconstruct the time-temperature (t-T) paths in the temperature range of 60–350°C. Eight t-T paths calculated along the across-strike section show that the cooling process of the HHC nappe in this study area is characterized by the following three aspects: (a) gradual cooling followed by rapid cooling and subsequent gradual cooling, (b) northward-younging of the timing of the rapid cooling, and (c) gradual cooling followed by <2 Myr rapid cooling in the frontmost part of the HHC nappe. The observed FT ages and t-T paths were then compared with those predicted by forwarding thermokinematic modeling. The results of the thermokinematic modeling for the “Flat-Ramp-Flat MHT model”, in which the HHC and the underlying LHS are denudated in direct proportion to the uplift of rocks transported along the Main Himalayan Thrust (MHT), reproduced the observed t-T paths and FT ages in eastern Nepal. This indicates that the observed FT ages and t-T paths reflect a denudation process driven by the movement of the MHT with a flat-ramp-flat geometry and that the denudation rate and its spatial distribution have roughly been constant in eastern Nepal since ca. 9 Ma

VLBI Monitoring Observations of Water Masers Around the Semi-Regular Variable Star R Crateris

We monitored water-vapor masers around the semi-regular variable star R Crateris with the Japanese VLBI Network (J-Net) at the 22 GHz band during four epochs with intervals of one month. The relative proper motions and Doppler-velocity drifts of twelve maser features were measured. Most of them existed for longer than 80 days. The 3-D kinematics of the features indicates a bipolar expanding flow. The major axis of the asymmetric flow was estimated to be at P.A. = 136 degrees. The existence of a bipolar outflow suggests that a Mira variable star had already formed a bipolar outflow. The water masers are in a region of apparent minimum radii of 1.3 x 10^12 m and maximum radii of 2.6 x 10^12 m, between which the expansion velocity ranges from 4.3 to 7.4 km/s. These values suggest that the water masers are radially accelerated, but still gravitationally bound, in the water-maser region. The most positive and negative velocity-drifting features were found relatively close to the systemic velocity of the star. We found that the blue-shifted features are apparently accelerated and the red-shifted apparently decelerated. The acceleration of only the blue-shifted features seems to be consistent with that of the expanding flow from the star.Comment: 15 pages, 5 figures, Accepted for publication in PASJ (2001), preprint can be obtained via WWW on http://www.nro.nao.ac.jp/library/report/list.htm

Jugular Vein Technique for Serial Blood Sampling in the Hamster

The puncture is performed via the external jugular vein in hamster (100g) under appropriate anesthesia and will give 1 ml within 30 seconds with certainty and security. Blood volumes up to 1 ml have been obtained once a week for a period of 20 weeks