The Stokes-Einstein Relation in Supercooled Aqueous Solutions of Glycerol

The diffusion of glycerol molecules decreases with decreasing temperature as its viscosity increases in a manner simply described by the Stokes-Einstein(SE) relation. Approaching the glass transition, this relation breaks down as it does with a number of other pure liquid glass formers. We have measured the diffusion coefficient for binary mixtures of glycerol and water and find that the Stokes-Einstein relation is restored with increasing water concentration. Our comparison with theory suggests that addition of water postpones the formation of frustration domainsComment: 4 Pages and 3 Figure

Galactic Binary Gravitational Wave Noise within LISA Frequency Band

Gravitational wave noise associated with unresolved binary stars in the Galaxy is studied with the special aim of determining the upper frequency at which it stops to contribute at the rms noise level of the proposed space-born interferometer (LISA). The upper limit to this background is derived from the statistics of SN Ia explosions, part of which can be triggered by binary white dwarf coalescences. The upper limiting frequency at which binary stochastic noise crosses LISA rms sensitivity is found to lie within the range 0.03-0.07 Hz, depending on the galactic binary white dwarf coalescence rate. To be reliably detectable by LISA, the energy density of relic cosmological background per logarithmic frequency interval should be Omega_{GW}h_{100}^2>10^{-8} at f>0.03 Hz.Comment: 16 pages with 1 eps figure, aasms4.sty, to appear in the ApJ vol. 494 February 20, 1998 issu

Statistical Mechanics of Glass Formation in Molecular Liquids with OTP as an Example

We extend our statistical mechanical theory of the glass transition from examples consisting of point particles to molecular liquids with internal degrees of freedom. As before, the fundamental assertion is that super-cooled liquids are ergodic, although becoming very viscous at lower temperatures, and are therefore describable in principle by statistical mechanics. The theory is based on analyzing the local neighborhoods of each molecule, and a statistical mechanical weight is assigned to every possible local organization. This results in an approximate theory that is in very good agreement with simulations regarding both thermodynamical and dynamical properties

Calibration of the distance scale from galactic Cepheids: I Calibration based on the GFG sample

New estimates of the distances of 36 nearby galaxies are presented based on accurate distances of galactic Cepheids obtained by Gieren, Fouque and Gomez (1998) from the geometrical Barnes-Evans method. The concept of 'sosie' is applied to extend the distance determination to extragalactic Cepheids without assuming the linearity of the PL relation. Doing so, the distance moduli are obtained in a straightforward way. The correction for extinction is made using two photometric bands (V and I) according to the principles introduced by Freedman and Madore (1990). Finally, the statistical bias due to the incompleteness of the sample is corrected according to the precepts introduced by Teerikorpi (1987) without introducing any free parameters (except the distance modulus itself in an iterative scheme). The final distance moduli depend on the adopted extinction ratio {R_V}/{R_I} and on the limiting apparent magnitude of the sample. A comparison with the distance moduli recently published by the Hubble Space Telescope Key Project (HSTKP) team reveals a fair agreement when the same ratio {R_V}/{R_I} is used but shows a small discrepancy at large distance. In order to bypass the uncertainty due to the metallicity effect it is suggested to consider only galaxies having nearly the same metallicity as the calibrating Cepheids (i.e. Solar metallicity). The internal uncertainty of the distances is about 0.1 magnitude but the total uncertainty may reach 0.3 magnitude.Comment: 12 pages, 4 figures, access to a database of extragalactic Cepheids. Astronomy & Astrophysics (in press) 200

Supernova rates from the Southern inTermediate Redshift ESO Supernova Search (STRESS)

To measure the supernova (SN) rates at intermediate redshift we performed the Southern inTermediate Redshift ESO Supernova Search (STRESS). Unlike most of the current high redshift SN searches, this survey was specifically designed to estimate the rate for both type Ia and core collapse (CC) SNe. We counted the SNe discovered in a selected galaxy sample measuring SN rate per unit blue band luminosity. Our analysis is based on a sample of ~43000 galaxies and on 25 spectroscopically confirmed SNe plus 64 selected SN candidates. Our approach is aimed at obtaining a direct comparison of the high redshift and local rates and at investigating the dependence of the rates on specific galaxy properties, most notably their colour. The type Ia SN rate, at mean redshift z=0.3, amounts to 0.22^{+0.10+0.16}_{-0.08 -0.14} h_{70}^2 SNu, while the CC SN rate, at z=0.21, is 0.82^{+0.31 +0.30}_{-0.24 -0.26} h_{70}^2 SNu. The quoted errors are the statistical and systematic uncertainties. With respect to local value, the CC SN rate at z=0.2 is higher by a factor of ~2 already at redshift, whereas the type Ia SN rate remains almost constant. This implies that a significant fraction of SN Ia progenitors has a lifetime longer than 2-3 Gyr. We also measured the SN rates in the red and blue galaxies and found that the SN Ia rate seems to be constant in galaxies of different colour, whereas the CC SN rate seems to peak in blue galaxies, as in the local Universe. SN rates per unit volume were found to be consistent with other measurements showing a steeper evolution with redshift for CC SNe with respect to SNe Ia. Finally we have exploited the link between star formation (SF) and SN rates to predict the evolutionary behaviour of the SN rates and compare it with the path indicated by observations.Comment: Accepted for publication in A&A; 25 pages (including on line material), 13 figure

Interferon β-1a in relapsing multiple sclerosis: four-year extension of the European IFNβ-1a Dose-C omparison Study

Background: Multiple sclerosis (MS) is a chronic disease requiring long-term monitoring of treatment. Objective: To assess the four-year clinical efficacy of intramuscular (IM) IFNb-1a in patients with relapsing MS from the European IFNb-1a Dose-C omparison Study. Methods: Patients who completed 36 months of treatment (Part 1) of the European IFNb-1a Dose-C omparison Study were given the option to continue double-blind treatment with IFNb-1a 30 mcg or 60 mcg IM once weekly (Part 2). Analyses of 48-month data were performed on sustained disability progression, relapses, and neutralizing antibody (NA b) formation. Results: O f 608/802 subjects who completed 36 months of treatment, 493 subjects continued treatment and 446 completed 48 months of treatment and follow-up. IFNb-1a 30 mcg and 60 mcg IM once weekly were equally effective for up to 48 months. There were no significant differences between doses over 48 months on any of the clinical endpoints, including rate of disability progression, cumulative percentage of patients who progressed (48 and 43, respectively), and annual relapse rates; relapses tended to decrease over 48 months. The incidence of patients who were positive for NAbs at any time during the study was low in both treatment groups. Conclusion: C ompared with 60-mcg IM IFNb-1a once weekly, a dose of 30 mcg IM IFNb-1a once weekly maintains the same clinical efficacy over four years

γ-Secretase inhibitor enhances antitumour effect of radiation in Notch-expressing lung cancer

BACKGROUND: Notch receptor has an important role in both development and cancer. We previously reported that inhibition of the Notch3 by γ-secretase inhibitor (GSI) induces apoptosis and suppresses tumour proliferation in non-small-cell lung cancer. Although radiation is reported to induce Notch activation, little is known about the relationship between radiation and Notch pathway. METHODS: We examined the effect of combining GSI and radiation at different dosing in three Notch expressing lung cancer cell lines. The cytotoxic effect of GSI and radiation was evaluated using MTT assay and clonogenic assay in vitro and xenograft models. Expressions of Notch pathway, mitogen-activated protein kinase (MAPK) pathway and Bcl-2 family proteins were investigated using western blot analysis. RESULTS: We discovered that the antitumour effect of combining GSI and radiation was dependent on treatment schedule. γ-Secretase inhibitor administration after radiation had the greatest growth inhibition of lung cancer in vitro and in vivo. We showed that the combination induced apoptosis of lung cancer cell lines through the regulation of MAPK and Bcl-2 family proteins. Furthermore, activation of Notch after radiation was ameliorated by GSI administration, suggesting that treatment with GSI prevents Notch-induced radiation resistance. CONCLUSION: Notch has an important role in lung cancer. Treatment with GSI after radiation can significantly enhance radiation-mediated tumour cytotoxicity