Catalytic surface effects on contaminated space shuttle tile in a dissociated nitrogen stream

Visual inspection revealed contamination on the surface of tiles removed from the lower section of the space shuttle orbiter after the second flight of Columbia (STS-2). Possible sources of this contamination and the effect on surface catalycity are presented

Nuclear symmetry energy and the r-mode instability of neutron stars

We analyze the role of the symmetry energy slope parameter $L$ on the {\it r}-mode instability of neutron stars. Our study is performed using both microscopic and phenomenological approaches of the nuclear equation of state. The microscopic ones include the Brueckner--Hartree--Fock approximation, the well known variational equation of state of Akmal, Pandharipande and Ravenhall, and a parametrization of recent Auxiliary Field Diffusion Monte Carlo calculations. For the phenomenological approaches, we use several Skyrme forces and relativisic mean field models. Our results show that the {\it r}-mode instability region is smaller for those models which give larger values of $L$. The reason is that both bulk ($\xi$) and shear ($\eta$) viscosities increase with $L$ and, therefore, the damping of the mode is more efficient for the models with larger $L$. We show also that the dependence of both viscosities on $L$ can be described at each density by simple power-laws of the type $\xi=A_{\xi}L^{B_\xi}$ and $\eta=A_{\eta}L^{B_\eta}$. Using the measured spin frequency and the estimated core temperature of the pulsar in the low-mass X-ray binary 4U 1608-52, we conclude that observational data seem to favor values of $L$ larger than $\sim 50$ MeV if this object is assumed to be outside the instability region, its radius is in the range $11.5-12$($11.5-13$) km, and its mass $1.4M_\odot$($2M_\odot$). Outside this range it is not possible to draw any conclusion on $L$ from this pulsar.Comment: 10 pages, 6 figures. Version published in Physical Review

Final Cultural Resources Report of the Salt Creek Midstream, LLC Proposed Olifant Eight Inch Pipeline Project on University Lands in Ward County, Texas

Enercon Services, Inc. (ENERCON), in support of Salt Creek Midstream, LLC, conducted an intensive archeological survey for the proposed Olifant Eight Inch Pipeline Project located near Pyote in Ward County, Texas. The proposed project consists of the construction of an approximately 800 foot (244 m) long eight inch steel pipeline on University Lands, extending from a tie-in at an existing well pad, trending generally south-southeast to a tie-in on the existing Quito Draw pipeline. The Olifant Eight Inch Pipeline Project area is mapped on the United States Geological Survey (USGS) Soda Lake NE, Texas (1967, photorevised 1981) 7.5 Minute Quadrangle map. The construction corridor consists of a 50 foot (15 m) wide permanent pipeline right-of-way (ROW) and a 50 foot (15 m) wide temporary workspace corridor. The cultural resources survey corridor and the area of potential effect (APE) was 100 feet (30 m) wide for the entire 800 foot (244 m) length of the proposed Olifant Eight Inch Pipeline Project, totaling 1.84 acres (.74 hectares). The proposed project is entirely on University Lands, a political subdivision of the State of Texas. The archeological survey was completed under Texas Antiquities Permit No. 9012. The cultural resources field investigation on University Lands was conducted on February 26, 2019 by ENERCON archeologist Gary Edington, who meets the U.S. Secretary of the Interior’s Professional Qualification Standards for archeology as set forth in 36 CFR 61, and consisted of an intensive pedestrian survey utilizing transects spaced no greater than 15 m apart, with shovel tests in areas which had the potential for buried cultural resources. The field investigation was conducted in accordance with the Texas Historical Commission (THC) Archeological Survey Standards for Texas. The entire project was supervised by Michael Margolis, an ENERCON archeologist who meets the U.S. Secretary of the Interior’s Professional Qualification Standards for archeology as set forth in 36 CFR 61. The cultural resources survey did not result in finding any historic or prehistoric artifacts, features, cultural lenses, or sites over 50 years of age on University Lands. Therefore, it is recommended that the project will have no effect on any historic property that may qualify for inclusion in the National Register of Historic Places (NRHP) on University Lands. No further cultural resources investigations are recommended prior to construction of the proposed Olifant Eight Inch Pipeline Project on University Lands. If cultural material, including sites, features, or artifacts that are 50 years old or older are encountered within the ROW during construction of this project, work in the area must cease and the THC must be immediately be notified

Pairing and alpha-like quartet condensation in N=Z nuclei

We discuss the treatment of isovector pairing by an alpha-like quartet condensate which conserves exactly the particle number, the spin and the isospin. The results show that the quartet condensate describes accurately the isovector pairing correlations in the ground state of systems with an equal number of protons and neutronsComment: 4 pages, to appear in Journal of Physics: Conference Serie

Neutrino Pair Bremsstrahlung in Neutron Star Crusts: a Reappraisal

We demonstrate that band-structure effects suppress bremsstrahlung of neutrino pairs by electrons in the crusts of neutron stars at temperatures of the order of $5\times 10^9 \,{\rm K}$ and below. Taking this into account, together with the fact that recent work indicates that the masses of neutron star crusts are considerably smaller than previously estimated, we find neutrino pair bremsstrahlung to be much less important for the thermal evolution of neutron stars than earlier calculations suggested.Comment: 11 plain LaTeX pages, 3 figures available on request, NORDITA-93/72 A/S/

Mu and Tau Neutrino Thermalization and Production in Supernovae: Processes and Timescales

We investigate the rates of production and thermalization of $\nu_\mu$ and $\nu_\tau$ neutrinos at temperatures and densities relevant to core-collapse supernovae and protoneutron stars. Included are contributions from electron scattering, electron-positron annihilation, nucleon-nucleon bremsstrahlung, and nucleon scattering. For the scattering processes, in order to incorporate the full scattering kinematics at arbitrary degeneracy, the structure function formalism developed by Reddy et al. (1998) and Burrows and Sawyer (1998) is employed. Furthermore, we derive formulae for the total and differential rates of nucleon-nucleon bremsstrahlung for arbitrary nucleon degeneracy in asymmetric matter. We find that electron scattering dominates nucleon scattering as a thermalization process at low neutrino energies ($\epsilon_\nu\lesssim 10$ MeV), but that nucleon scattering is always faster than or comparable to electron scattering above $\epsilon_\nu\simeq10$ MeV. In addition, for $\rho\gtrsim 10^{13}$ g cm$^{-3}$, $T\lesssim14$ MeV, and neutrino energies $\lesssim60$ MeV, nucleon-nucleon bremsstrahlung always dominates electron-positron annihilation as a production mechanism for $\nu_\mu$ and $\nu_\tau$ neutrinos.Comment: 29 pages, LaTeX (RevTeX), 13 figures, submitted to Phys. Rev. C. Also to be found at anonymous ftp site http://www.astrophysics.arizona.edu; cd to pub/thompso