Separating baryons and dark matter in cluster cores: a full 2-D lensing and dynamic analysis of Abell 383 and MS2137-23

(abridged) We utilize existing imaging and spectroscopic data for the galaxy clusters MS2137-23 and Abell 383 to present improved measures of the distribution of dark and baryonic material in the clusters' central regions. Our method, based on the combination of gravitational lensing and dynamical data, is uniquely capable of separating the distribution of dark and baryonic components at scales below 100 kpc. We find a variety of strong lensing models fit the available data, including some with dark matter profiles as steep as expected from recent simulations. However, when combined with stellar velocity dispersion data for the brightest member, shallower inner slopes than predicted by numerical simulations are preferred. For Abell 383, the preferred shallow inner slopes are statistically a good fit only when the multiple image position uncertainties associated with our lens model are assumed to be 0\farcs5, to account for unknown substructure. No statistically satisfactory fit was obtained matching both the multiple image lensing data and the velocity dispersion profile of the brightest cluster galaxy in MS2137-23. This suggests that the mass model we are using, which comprises a pseudo-elliptical generalized NFW profile and a brightest cluster galaxy component may inadequately represent the inner cluster regions. This may plausibly arise due to halo triaxiality or by the gravitational interaction of baryons and dark matter in cluster cores. However, the progress made via this detailed study highlights the key role that complementary observations of lensed features and stellar dynamics offer in understanding the interaction between dark and baryonic matter on non-linear scales in the central regions of clusters.Comment: 18 pages, 9 figures; accepted for publication in the Astrophysical Journa

Non-Critical Liouville String Escapes Constraints on Generic Models of Quantum Gravity

It has recently been pointed out that generic models of quantum gravity must contend with severe phenomenological constraints imposed by gravitational Cerenkov radiation, neutrino oscillations and the cosmic microwave background radiation. We show how the non-critical Liouville-string model of quantum gravity we have proposed escapes these constraints. It gives energetic particles subluminal velocities, obviating the danger of gravitational Cerenkov radiation. The effect on neutrino propagation is naturally flavour-independent, obviating any impact on oscillation phenomenology. Deviations from the expected black-body spectrum and the effects of time delays and stochastic fluctuations in the propagation of cosmic microwave background photons are negligible, as are their effects on observable spectral lines from high-redshift astrophysical objects.Comment: 15 pages LaTeX, 2 eps figures include

Dynamical Formation of Horizons in Recoiling D Branes

A toy calculation of string/D-particle interactions within a world-sheet approach indicates that quantum recoil effects - reflecting the gravitational back-reaction on space-time foam due to the propagation of energetic particles - induces the appearance of a microscopic event horizon, or `bubble', inside which stable matter can exist. The scattering event causes this horizon to expand, but we expect quantum effects to cause it to contract again, in a `bounce' solution. Within such `bubbles', massless matter propagates with an effective velocity that is less than the velocity of light in vacuo, which may lead to observable violations of Lorentz symmetry that may be tested experimentally. The conformal invariance conditions in the interior geometry of the bubbles select preferentially three for the number of the spatial dimensions, corresponding to a consistent formulation of the interaction of D3 branes with recoiling D particles, which are allowed to fluctuate independently only on the D3-brane hypersurface.Comment: 25 pages LaTeX, 4 eps figures include

Solid Oxide Fuel Cell Process and Apparatus

Conveying gas containing sulfur through a sulfur tolerant planar solid oxide fuel cell (PSOFC) stack for sulfur scrubbing, followed by conveying the gas through a non-sulfur tolerant PSOFC stack. The sulfur tolerant PSOFC stack utilizes anode materials, such as LSV, that selectively convert H2S present in the fuel stream to other non-poisoning sulfur compounds. The remaining balance of gases remaining in the completely or near H2S-free exhaust fuel stream is then used as the fuel for the conventional PSOFC stack that is downstream of the sulfur-tolerant PSOFC. A broad range of fuels such as gasified coal, natural gas and reformed hydrocarbons are used to produce electricity

Antibody Levels in Beef Calves (Birth through Weaning) Following \u3ci\u3eClostridium perfringens \u3c/i\u3eType C Toxoid and/or Antitoxin Administration

According to National Cattlemen\u27s Association data, there are approximately 35 million beef cows and 10 million dairy cows in the United States. Combining pre-calving, pre-weaning, yearling, breeding bulls and replacement heifer vaccination opportunities to utilize Clostridial immunization programs, it is estimated that well in excess of 100 million doses of various Clostridial containing products are used each year. Knowing which products stimulate satisfactory antibody levels and their duration of response is an essential part of making informed recommendations to producers for controlling disease. Presently, non-industry, controlled field studies assessing Clostridial products are not available. Specifically, Clostridium perfringens Type C is a common cause of neonatal calf diarrhea. Although histopathological diagnoses of this disease are made, these cases are frequently difficult to confirm. They are often referred to as sudden/unknown death in calves. From 18 veterinary diagnostic laboratories across the United States contributing to the USDA:APHIS:VS DxMONITOR (summer, 1992), 237 suspected cases of Clostridium perfringens Types C were tested during the period January 1, 1992 to March 31, 1992, but only 22 cases were confirmed. As such, Veterinary Clinicians must rely on gross necropsy results and frequently make recommendations with limited confirmatory information. Anecdotal information from several veterinary clinicians suggests that the incidence of these non-confirmed diagnoses diminished greatly with the use of Clostridium perfringens C&D products prophylactically. Various opinions abound as to whether the best response to controlling Clostridium perfringens Type C or sudden death in young beef calves is achieved with the use of toxoid, antitoxin, or both, and whether an acceptable response is achieved by administration at birth, two-weeks, or at two-months-of-age. Lack of definitive information regarding optimum protection afforded by the use of these products and their timing leads to possible ineffective use. This, therefore, results in increased cost of the production by both product purchase and labor, and possible increased tissue damage as observed by several Beef Quality Assurance Programs using 7-way Clostridial products

Antibody Levels in Beef Calves (Birth through Weaning) Following \u3ci\u3eClostridium perfringens \u3c/i\u3eType C Toxoid and/or Antitoxin Administration

According to National Cattlemen\u27s Association data, there are approximately 35 million beef cows and 10 million dairy cows in the United States. Combining pre-calving, pre-weaning, yearling, breeding bulls and replacement heifer vaccination opportunities to utilize Clostridial immunization programs, it is estimated that well in excess of 100 million doses of various Clostridial containing products are used each year. Knowing which products stimulate satisfactory antibody levels and their duration of response is an essential part of making informed recommendations to producers for controlling disease. Presently, non-industry, controlled field studies assessing Clostridial products are not available. Specifically, Clostridium perfringens Type C is a common cause of neonatal calf diarrhea. Although histopathological diagnoses of this disease are made, these cases are frequently difficult to confirm. They are often referred to as sudden/unknown death in calves. From 18 veterinary diagnostic laboratories across the United States contributing to the USDA:APHIS:VS DxMONITOR (summer, 1992), 237 suspected cases of Clostridium perfringens Types C were tested during the period January 1, 1992 to March 31, 1992, but only 22 cases were confirmed. As such, Veterinary Clinicians must rely on gross necropsy results and frequently make recommendations with limited confirmatory information. Anecdotal information from several veterinary clinicians suggests that the incidence of these non-confirmed diagnoses diminished greatly with the use of Clostridium perfringens C&D products prophylactically. Various opinions abound as to whether the best response to controlling Clostridium perfringens Type C or sudden death in young beef calves is achieved with the use of toxoid, antitoxin, or both, and whether an acceptable response is achieved by administration at birth, two-weeks, or at two-months-of-age. Lack of definitive information regarding optimum protection afforded by the use of these products and their timing leads to possible ineffective use. This, therefore, results in increased cost of the production by both product purchase and labor, and possible increased tissue damage as observed by several Beef Quality Assurance Programs using 7-way Clostridial products

Testing A (Stringy) Model of Quantum Gravity

I discuss a specific model of space-time foam, inspired by the modern non-perturbative approach to string theory (D-branes). The model views our world as a three brane, intersecting with D-particles that represent stringy quantum gravity effects, which can be real or virtual. In this picture, matter is represented generically by (closed or open) strings on the D3 brane propagating in such a background. Scattering of the (matter) strings off the D-particles causes recoil of the latter, which in turn results in a distortion of the surrounding space-time fluid and the formation of (microscopic, i.e. Planckian size) horizons around the defects. As a mean-field result, the dispersion relation of the various particle excitations is modified, leading to non-trivial optical properties of the space time, for instance a non-trivial refractive index for the case of photons or other massless probes. Such models make falsifiable predictions, that may be tested experimentally in the foreseeable future. I describe a few such tests, ranging from observations of light from distant gamma-ray-bursters and ultra high energy cosmic rays, to tests using gravity-wave interferometric devices and terrestrial particle physics experients involving, for instance, neutral kaons.Comment: 25 pages LATEX, four figures incorporated, uses special proceedings style. Invited talk at the third international conference on Dark Matter in Astro and Particle Physics, DARK2000, Heidelberg, Germany, July 10-15 200

Cavity-enhanced radiative emission rate in a single-photon-emitting diode operating at 0.5 GHz

We report the observation of a Purcell enhancement in the electroluminescence decay rate of a single quantum dot, embedded in a microcavity light-emitting-diode structure. Lateral confinement of the optical mode was achieved using an annulus of low-refractive-index aluminium oxide, formed by wet oxidation. The same layer acts as a current aperture, reducing the active area of the device without impeding the electrical properties of the p-i-n diode. This allowed single photon electroluminescence to be demonstrated at repetition rates up to 0.5 GHz.Comment: 11 pages, 4 Figures. To be published in New Journal of Physic

Jet Investigations Using the Radial Moment

We define the radial moment, , for jets produced in hadron-hadron collisions. It can be used as a tool for studying, as a function of the jet transverse energy and pseudorapidity, radiation within the jet and the quality of a perturbative description of the jet shape. We also discuss how non-perturbative corrections to the jet transverse energy affect .Comment: 14 pages, LaTeX, 6 figure