Axion-like-particle decay in strong electromagnetic backgrounds

The decay of a massive pseudoscalar, scalar and U(1) boson into an electron-positron pair in the presence of strong electromagnetic backgrounds is calculated. Of particular interest is the constant-crossed-field limit, relevant for experiments that aim to measure high-energy axion-like-particle conversion into electron-positron pairs in a magnetic field. The total probability depends on the quantum nonlinearity parameter - a product of field and lightfront momentum invariants. Depending on the seed particle mass, different decay regimes are identified. In the below-threshold case, we find the probability depends on a non-perturbative tunnelling exponent depending on the quantum parameter and the particle mass. In the above-threshold case, we find that when the quantum parameter is varied linearly, the probability oscillates nonlinearly around the spontaneous decay probability. A strong-field limit is identified in which the threshold is found to disappear. In modelling the fall-off of a quasi-constant-crossed magnetic field, we calculate probabilities beyond the constant limit and investigate when the decay probability can be regarded as locally constant.Comment: 22 pages, 7 figure

Constructive counterexamples to additivity of minimum output R\'enyi entropy of quantum channels for all p>2

We present a constructive example of violation of additivity of minimum output R\'enyi entropy for each p>2. The example is provided by antisymmetric subspace of a suitable dimension. We discuss possibility of extension of the result to go beyond p>2 and obtain additivity for p=0 for a class of entanglement breaking channels.Comment: 4 pages; a reference adde

Dielectric molding apparatus Patent

Dielectric apparatus for heating, fusing, and hardening of organic matrix to form plastic material into shaped produc

Saturated laser fluorescence in turbulent sooting flames at high pressure

The primary objective was to develop a quantitative, single pulse, laser-saturated fluorescence (LSF) technique for measurement of radical species concentrations in practical flames. The species of immediate interest was the hydroxyl radical. Measurements were made in both turbulent premixed diffusion flames at pressures between 1 and 20 atm. Interferences from Mie scattering were assessed by doping with particles or by controlling soot loading through variation of equivalence ratio and fuel type. The efficacy of the LSF method at high pressure was addressed by comparing fluorescence and adsorption measurements in a premixed, laminar flat flame at 1-20 atm. Signal-averaging over many laser shots is sufficient to determine the local concentration of radical species in laminar flames. However, for turbulent flames, single pulse measurements are more appropriate since a statistically significant number of laser pulses is needed to determine the probability function (PDF). PDFs can be analyzed to give true average properties and true local kinetics in turbulent, chemically reactive flows

Model for the unidirectional motion of a dynein molecule

Cytoplasmic dyneins transport cellular organelles by moving on a microtubule filament. It has been found recently that depending on the applied force and the concentration of the adenosine triphosphate (ATP) molecules, dynein's step size varies. Based on these studies, we propose a simple model for dynein's unidirectional motion taking into account the variations in its step size. We study how the average velocity and the relative dispersion in the displacement vary with the applied load. The model is amenable to further extensions by inclusion of details associated with the structure and the processivity of the molecule.Comment: 10 pages, 5 figure

Molding a high-density laminate

Molding press is used to form phenolic resin impregnated glass fiber cloth into a high-density, cylindrical-ring laminate. The press applies clamping pressure and heat to a mold containing the glass fiber cloth laminate, which has hydrostatic pressure applied to it by means of a specially designed pressure plug

The causes of full ocean depth interannual variability in Drake Passage

In recent years a number of large scale modes of Southern Hemisphere climate variability have been observed, most notably the Southern Annular Mode (SAM, e.g. Thompson and Solomon, 2002), the Pacific South American modes (PSA, e.g. Mo and Peagle, 2001), the Antarctic Dipole (e.g. Martinson and Ianuzzi, 2003), the Antarctic Circumpolar Wave (e.g. White and Peterson, 1996), and of course the El Niño Southern Oscillation (ENSO). All have pronounced effects over or in the Southern Ocean, and may be expected to account for a significant part of the interannual variability observed there. Most studies analyse these phenomena from a large-scale point of view, often by extracting modes from Southern Hemisphere atmospheric and oceanic fields using various mathematical techniques. In this study we have taken an alternative approach, and tried to understand the causes of the full ocean depth variability in Drake Passage observed in the WOCE SR1b repeat hydrographic sections (Cunningham et al. 2003)