Isolated Light Chain of Tetanus Toxin Inhibits Exocytosis: Studies in Digitonin-Permeabilized Cells

Previous work indicates that the heavy chain of tetanus toxin is responsible for the binding of the toxin to the neuronal membrane and its subsequent internalization. In the present study, the light chain of tetanus toxin mimicked the holotoxin in inhibiting Ca 2+ -dependent secretion of [ 3 H]norepinephrine from digitonin-permeabilized adrenal chromaffin cells. Preincubation of tetanus toxin with monoclonal antibodies to the light chain prevented the inhibition by tetanus toxin. Preincubation of tetanus toxin with nonimmune ascites fluid or with monoclonal antibodies directed against the C fragment (the C-terminal of the heavy chains or the heavy-chain portion of the B fragment did not prevent inhibition by tetanus toxin. The data indicate that the light chain is responsible for the intracellular blockade of exostosis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65694/1/j.1471-4159.1989.tb11800.x.pd

Muon Simulations for Super-Kamiokande, KamLAND and CHOOZ

Muon backgrounds at Super-Kamiokande, KamLAND and CHOOZ are calculated using MUSIC. A modified version of the Gaisser sea level muon distribution and a well-tested Monte Carlo integration method are introduced. Average muon energy, flux and rate are tabulated. Plots of average energy and angular distributions are given. Implications on muon tracker design for future experiments are discussed.Comment: Revtex4 33 pages, 16 figures and 4 table

No anomalous supersaturation in ultracold cirrus laboratory experiments

High-altitude cirrus clouds are climatically important: their formation freeze-dries air ascending to the stratosphere to its final value, and their radiative impact is disproportionately large. However, their formation and growth are not fully understood, and multiple in situ aircraft campaigns have observed frequent and persistent apparent water vapor supersaturations of 5 %–25 % in ultracold cirrus (T<205 K), even in the presence of ice particles. A variety of explanations for these observations have been put forth, including that ultracold cirrus are dominated by metastable ice whose vapor pressure exceeds that of hexagonal ice. The 2013 IsoCloud campaign at the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud and aerosol chamber allowed explicit testing of cirrus formation dynamics at these low temperatures. A series of 28 experiments allows robust estimation of the saturation vapor pressure over ice for temperatures between 189 and 235 K, with a variety of ice nucleating particles. Experiments are rapid enough (∼10 min) to allow detection of any metastable ice that may form, as the timescale for annealing to hexagonal ice is hours or longer over the whole experimental temperature range. We show that in all experiments, saturation vapor pressures are fully consistent with expected values for hexagonal ice and inconsistent with the highest values postulated for metastable ice, with no temperature-dependent deviations from expected saturation vapor pressure. If metastable ice forms in ultracold cirrus clouds, it appears to have a vapor pressure indistinguishable from that of hexagonal ice to within about 4.5 %

Search for Dark Matter WIMPs using Upward Through-going Muons in Super-Kamiokande

We present the results of indirect searches for Weakly Interacting Massive Particles (WIMPs) with 1679.6 live days of data from the Super-Kamiokande detector using neutrino-induced upward through-going muons. The search is performed by looking for an excess of high energy muon neutrinos from WIMP annihilations in the Sun, the core of the Earth, and the Galactic Center, as compared to the number expected from the atmospheric neutrino background. No statistically significant excess was seen. We calculate flux limits in various angular cones around each of the above celestial objects. We obtain conservative model-independent upper limits on WIMP-nucleon cross-section as a function of WIMP mass and compare these results with the corresponding results from direct dark matter detection experiments.Comment: 10 pages, 14 figures, Submitted to Phys. Rev.

Observation of the east-west anisotropy of the atmospheric neutrino flux

The east-west anisotropy, caused by the deflection of primary cosmic rays in the Earth's magnetic field, is observed for the first time in the flux of atmospheric neutrinos. Using a 45 kt-year exposure of the Super-Kamiokande detector, 552 e-like and 633 mu-like horizontally-going events are selected in the momentum range between 400 and 3000 MeV/c. The azimuthal distribution of e-like and mu-like events agrees with the expectation from atmospheric neutrino flux calculations that account for the geomagnetic field, verifying that the geomagnetic field effects in the production of atmospheric neutrinos in the GeV energy range are well understood.Comment: 8 pages,3 figures revtex, submitted to PR

Solar neutrino measurements in Super-Kamiokande-I

The details of Super--Kamiokande--I's solar neutrino analysis are given. Solar neutrino measurement in Super--Kamiokande is a high statistics collection of $^8$B solar neutrinos via neutrino-electron scattering. The analysis method and results of the 1496 day data sample are presented. The final oscillation results for the data are also presented.Comment: 32pages, 57figures, submitted to Physical Review