Experimental and computational analyses reveal that environmental restrictions shape HIV-1 spread in 3D cultures

Here, using an integrative experimental and computational approach, Imle et al. show how cell motility and density affect HIV cell-associated transmission in a three-dimensional tissue-like culture system of CD4+ T cells and collagen, and how different collagen matrices restrict infection by cell-free virions

Experiment to measure the electron neutrino mass using a frozen tritium source

We are performing an experiment to determine the electron neutrino mass with the precision of a few eV by measuring the tritium beta decay energy distribution near the endpoint. Key features of the experiment are a 2 eV resolution electrostatic spectrometer and a high-activity frozen tritium source. It is important that the source have electronic wavefunctions which can be accurately calculated. These calculations can be precisely made for tritium and the HeT/sup +/ daughter ion and allow determination of branching fractions to 0.1% and energy of the excited states to 0.1 eV. We discuss the excited final molecular state calculations and describe the experimental apparatus. 2 references, 6 figures

Solar models and solar neutrino oscillations

We provide a summary of the current knowledge, theoretical and experimental, of solar neutrino fluxes and of the masses and mixing angles that characterize solar neutrino oscillations. We also summarize the principal reasons for doing new solar neutrino experiments and what we think may be learned from the future measurements.Comment: Submitted to the Neutrino Focus Issue of New Journal of Physics at http://www.njp.or

Molecular effects in the neutrino mass determination from beta-decay of the tritium molecule

Molecular final state energies and transition probabilities have been computed for beta-decay of the tritium molecule. The results are of sufficient accuracy to make a determination of the electron neutrino rest mass with an error not exceeding a few tenths of an electron volt. Effects of approximate models of tritium beta-decay on the neutrino mass determination are discussed. 14 refs., 3 figs., 1 tab

A search for direct muon production in the forward direction

We propose to search for direct muon production in the forward direction from 300 GeV protons incident on a heavy nuclear target. By using the first stage of the Ml beam as a source of a diffracted proton beam and the second and third stages of Ml as a spectrometer, one can make a measurement of the direct muon to pion ratio at values of x between 0.3 and 0.75. If this ratio is on the order of 10{sup -4}, the event rates are on the order of 800 direct muons/hr. at an x of .5. The modifications to the Ml beam are minor

Testing the inverse-square law of gravity on a 465-m tower

We have performed a test of Newton’s universal theory of gravitation by comparing gravity measured on a tower to an upward continuation of the surface gravity field. We measured gravity at 12 heights on a 465-m tower at the Nevada Test Site and, in addition, made measurements at 281 locations on the ground. The surface points fell within 91 optimally chosen sectors that extended out to 2.6 km from the tower. These data were combined with 60000 additional surface gravity measurements within 300 km of the tower. We used a surface integral derived from Laplace’s equation to upward continue the surface gravity field and our observations are consistent with the Newtonian predictions to within (-60±95)×10^-8 m sec^-2 at the top of the tower

An experiment to measure the electron neutrino mass using a cryogenic tritium source

An experiment has been performed to determine the electron neutrino mass with the precision of a few eV by measuring the tritium beta decay energy distribution near the endpoint. Key features of the experiment are a 2 eV resolution electrostatic spectrometer and a high-activity frozen tritium source. It is important that the source have electronic wavefunctions which can be accurately calculated. These calculations have been made for tritium and the HeT/sup +/ daughter ion and allow determination of branching fractions to 0.1% and energy of the excited states to 0.1 eV. The excited final molecular state calculations and the experimental apparatus are discussed. 4 refs., 5 figs

Damping of supernova neutrino transitions in stochastic shock-wave density profiles

Supernova neutrino flavor transitions during the shock wave propagation are known to encode relevant information not only about the matter density profile but also about unknown neutrino properties, such as the mass hierarchy (normal or inverted) and the mixing angle theta_13. While previous studies have focussed on "deterministic" density profiles, we investigate the effect of possible stochastic matter density fluctuations in the wake of supernova shock waves. In particular, we study the impact of small-scale fluctuations on the electron (anti)neutrino survival probability, and on the observable spectra of inverse-beta-decay events in future water-Cherenkov detectors. We find that such fluctuations, even with relatively small amplitudes, can have significant damping effects on the flavor transition pattern, and can partly erase the shock-wave imprint on the observable time spectra, especially for sin^2(theta_13) > O(10^-3).Comment: v2 (23 pages, including 6 eps figures). Typos removed, references updated, matches the published versio