Baryon Number Transport in a Cosmic QCD-Phase Transition

We investigate the transport of baryon number across phase boundaries in a putative first order QCD-phase transition. Two independent phenomenological models are employed to estimate the baryon penetrability at the phase boundary: chromoelectric flux tube models; and an analogy to baryon-baryon coalescence in nuclear physics. Our analysis indicates that baryon transport across phase boundaries may be order of magnitude more efficient than other work has suggested. We discuss the substantial uncertainties involved in estimating baryon penetrability at phase boundaries.Comment: 25 pages, 4 figures (available upon request by mail or fax), plain tex, UCRL-JC-00000

An evaluation of the utilization of remote sensing in resource and environmental management of the Chesapeake Bay region

A nine-month study was conducted to assess the effectiveness of the NASA Wallops Chesapeake Bay Ecological Program in remote sensing. The study consisted of a follow-up investigation and information analysis of actual cases in which remote sensing was utilized by management and research personnel in the Chesapeake Bay region. The study concludes that the NASA Wallops Chesapeake Bay Ecological Program is effective, both in terms of costs and performance

Librarians as Members of Integrated Institutional Information Programs: Management and Organizational Issues

published or submitted for publicatio

Bearing detection in the presence of two sources of varying coherence using the complex cepstrum

The effect of the presence of two acoustic sources (one, the primary, whose location is to be detected) of varying coherence on a cepstral bearing finding procedure is experimentally studied. The coherence between the acoustic sources was altered by adding random noise of various SNR (signal-to-noise ratio) to the input signal of the primary source; the same base signal being fed to both sources. The results demonstrate that, when block liftering is used, the primary source bearing is reliably estimated for coherences as low as gamma sup 2 greater than or approx equal to 0.5. The results also imply that background noise (unreflected) of SNR greater than or approx equal to 10 dB will not markedly affect the accuracy of the bearing estimation algorithm

User's manual for PRESTO: A computer code for the performance of regenerative steam turbine cycles

Standard turbine cycles for baseload power plants and cycles with such additional features as process steam extraction and induction and feedwater heating by external heat sources may be modeled. Peaking and high back pressure cycles are also included. The code's methodology is to use the expansion line efficiencies, exhaust loss, leakages, mechanical losses, and generator losses to calculate the heat rate and generator output. A general description of the code is given as well as the instructions for input data preparation. Appended are two complete example cases

Absence of a Lower Limit on Omega_b in Inhomogeneous Primordial Nucleosynthesis

We show that a class of inhomogeneous big bang nucleosynthesis models exist which yield light-element abundances in agreement with observational constraints for baryon-to-photon ratios significantly smaller than those inferred from standard homogeneous big bang nucleosynthesis (HBBN). These inhomogeneous nucleosynthesis models are characterized by a bimodal distribution of baryons in which some regions have a local baryon-to-photon ratio eta=3*10e-10, while the remaining regions are baryon-depleted. HBBN scenarios with primordial (2H+3He)/H<9*10e-5 necessarily require that most baryons be in a dark or non-luminous form, although new observations of a possible high deuterium abundance in Lyman-alpha clouds may relax this requirement somewhat. The models described here present another way to relax this requirement and can even eliminate any lower bound on the baryon-to-photon ratio.Comment: 13 pages, 2 figures (available upon request by email), plain te

Presupernova collapse models with improved weak-interaction rates

Improved values for stellar weak interaction rates have been recently calculated based upon a large shell model diagonalization. Using these new rates (for both beta decay and electron capture), we have examined the presupernova evolution of massive stars in the range 15-40 Msun. Comparing our new models with a standard set of presupernova models by Woosley and Weaver, we find significantly larger values for the electron-to-baryon ratio Ye at the onset of collapse and iron core masses reduced by approximately 0.1 Msun. The inclusion of beta-decay accounts for roughly half of the revisions, while the other half is a consequence of the improved nuclear physics. These changes will have important consequences for nucleosynthesis and the supernova explosion mechanism.Comment: 4 pages, 2 figure

Enhanced Heavy-Element Formation in Baryon-Inhomogeneous Big-Bang Models

We show that primordial nucleosynthesis in baryon inhomogeneous big-bang models can lead to significant heavy-element production while still satisfying all the light-element abundance constraints including the low lithium abundance observed in population II stars. The parameters which admit this solution arise naturally from the process of neutrino induced inflation of baryon inhomogeneities prior to the epoch of nucleosynthesis. These solutions entail a small fraction of baryons (\le 2\%) in very high density regions with local baryon-to-photon ratio $\eta^h\approx 10^{-4}$, while most baryons are at a baryon-to-photon ratio which optimizes the agreement with light-element abundances. The model would imply a unique signature of baryon inhomogeneities in the early universe, evidenced by the existence of primordial material containing heavy-element products of proton and alpha- burning reactions with an abundance of $[Z]\sim -6 to -4$.Comment: 19 pages in plain Tex, 5 figures (not included) available by fax or mail upon request, ApJ in press, L