Weekly student newspaper from Tarleton State University in Stephenville, Texas that includes local, state and campus news along with advertising.

We report numerical computations of the PAC perturbation factor G{sub 2}(t) for spin 5/2 nuclei subject to a static EFG symmetric about the z-axis and an additional axially-symmetric EFG hose symmetry axis fluctuates randomly among the x,y,z directions. For sufficiently large fluctuation rates, the numerical results are described by the expression for the static interaction alone with the addition of relaxation terms. Results of applying this model to {sup 111}Cd TDPAC measurements on tetragonal ZrO{sub 2} are described briefly. The model allows one to evaluate the probability that oxygen vacancies are trapped, the energy of association of vacancy-metal pairs, and the vacancy activation energy of motion. 4 refs., 3 figs.

Perturbed angular correlation measurements in tetragonal and cubic zirconia and in ceria are described. A physically reasonable and self-consistent interpretation of these data implies that oxygen vacancies are trapped at a second neighbor position by Cd in tetragonal zirconia and by In in ceria. For Cd in tetragonal zirconia, the vacancy trap energy is found to be 0.44 eV, and the energy barrier between adjacent trap sites is approximately 0.8 eV. The activation energy of an oxygen vacancy hopping between trap sites around {sup 111}Cd in ceria is found to be 0.55 eV. The activation energy for oxygen vacancy hopping in cubic zirconia, as detected by {sup 181}Ta PAC, is about 1.0 eV and independent of the Y concentration. 12 refs., 4 figs.

Using Blume's stochastic model and the approach of Winkler and Gerdau, we have computed-time-dependent effects on perturbed angular correlation (PAC) spectra due to defect motion in solids in the case of I = (5/2) electric quadrupole interactions. We report detailed analysis for a family of simple models: XYZ + Z'' models, in which the symmetry axis of an axial efg is allowed to fluctuate among orientations along x, y, and z axes, and a static axial efg oriented along the z axis is added to the fluctuating efgs. When the static efg is zero, this model is termed the XYZ'' model. Approximate forms are given for G{sub 2}(t) in the slow and rapid fluctuation regimes, i.e. suitable for the low and high temperature regions, respectively. Where they adequately reflect the underlying physical processes, these expressions allow one to fit PAC data for a wide range of temperatures and dopant concentrations to a single model, thus increasing the uniqueness of the interpretation of the defect properties. Application of the models are given for zirconia and ceria ceramics. 14 refs.

Many enhanced oil recovery (EOR) processes involve injecting an agent, such as steam or CO{sub 2}, that is much more mobile than the resident oil. Other EOR processes attempt to improve sweep efficiency by adding polymer or surfactant to the injected water to create a favorable mobility ratio. This study examines the effect of statistically generated heterogeneity on miscible displacements at unfavorable and favorable mobility ratios. The principal goal is to delineate the effects of fingering, dispersion and channeling on volumetric sweep efficiency. Two-dimensional heterogeneous permeability fields are generated with variability (heterogeneity) and spatial correlation as characterizing parameters. Four levels of correlation and three of variability make up a 12 element matrix. At each element of the matrix, a miscible displacement simulation at unit mobility ratio shows the effect of the heterogeneity, and simulations at mobility ratios of 10 and 0.5 show the effect of viscous force differences combined with heterogeneity. 20 refs., 7 figs., 3 tabs.

The purpose of this report is to present water-balance data collected in 1988 and 1989 from the 300 Area Buried Waste Test Facility and Grass Site, and the 200 East Area closed-bottom lysimeter. This report is an annual update of previous recharge status reports by Gee, Rockhold, and Downs, and Gee. Data from several other lysimeter sites are included for comparison. 43 refs., 28 figs., 7 tabs.

We review the status of Green's Function Monte Carlo (GFMC) methods as applied to problems in nuclear physics. New methods have been developed to handle the spin and isospin degrees of freedom that are a vital part of any realistic nuclear physics problem, whether at the level of quarks or nucleons. We discuss these methods and then summarize results obtained recently for light nuclei, including ground state energies, three-body forces, charge form factors and the coulomb sum. As an illustration of the applicability of GFMC to quark models, we also consider the possible existence of bound exotic multi-quark states within the framework of flux-tube quark models. 44 refs., 8 figs., 1 tab.

Identification of products formed by the reaction of plutonium metal with liquid water at 23{degree}C indicates that the plutonium-oxygen phase diagram is similar to the cerium-oxygen and praseodymium-oxygen diagrams. Quantitative measurements of H{sub 2} formation and analytical data suggest that a sequence of hydrolysis reactions produces oxide hydrides of trivalent plutonium, Pu{sub 2}O{sub 3}, mixed-valent oxides and PuO{sub 2}. The intermediate oxides are the n {equals} 7, 9, 10 and 12 members of the Pu{sub n}O{sub 2n{minus}2} homologous series. Properties of the residue formed by thermal decomposition of the initial hydrolysis product, plutonium monoxide monhydride (PuOH), are consistent with the formation of metastable plutonium monoxide. Crystal-chemical, thermodynamic, and kinetic factors are evaluated, but definitive assignment of the equilibrium Pu-O diagram is not possible. 22 refs., 6 figs., 1 tab.

Daily newspaper from Perry, Oklahoma that includes local, state, and national news along with advertising.

A geothermal gradient core hole (TCB-1) was drilled to a depth of 700+ m at the Tecuamburro geothermal site, Guatemala during February and March, 1990. The core hole is located low on the northern flank of the Tecuamburro Volcano complex. Preliminary analysis of cores (>98% core recovery) indicates that the hydrothermal system may be centered in the 4-km-diameter Chupadero Crater, which has been proposed as the source of pyroxene pumice deposits in the Tecuamburro area. TCB-1 is located 300 m south of a 300-m-diameter phreatic crater, Laguna Ixpaco; the core hole penetrates the thin edge of a tuff ring surrounding Ixpaco and zones of hydrothermal brecciation within the upper 150 m may be related to the phreatic blast, dated at 2,910 {sup 14}C years. At the time of this writing, the unequilibrated temperature at a depth of 570m was 180{degree}C. Data on fracturing, permeability, hydrothermal alteration, and temperature will be presented. 3 refs., 3 figs.

Daily newspaper from Perry, Oklahoma that includes local, state, and national news along with advertising.

Daily newspaper from Perry, Oklahoma that includes local, state, and national news along with advertising.

Daily newspaper from Perry, Oklahoma that includes local, state, and national news along with advertising.

Daily newspaper from Perry, Oklahoma that includes local, state, and national news along with advertising.

Daily newspaper from Perry, Oklahoma that includes local, state, and national news along with advertising.

Daily newspaper from Perry, Oklahoma that includes local, state, and national news along with advertising.

Weekly newspaper from Clifton, Texas that includes local, state, and national news along with advertising.

Weekly newspaper from Clifton, Texas that includes local, state, and national news along with advertising.

Monthly newspaper from Oklahoma City, Oklahoma that includes news and information about the Churches of Christ along with advertising.

We have investigated a new continuum {gamma}-ray spectroscopy technique which is based on the detection of all emitted {gamma} rays in a 4{pi} detector system, and ordering them according to their energies on an event-by-event basis. The technique allows determination of gamma strength functions, and rotational damping width as a function of spin and temperature. Thus, it opens up the possibility of studying the onset of motional narrowing, order-to-chaos transition, and the mapping of the evolution of nuclear collectivity with a spin and temperature. Application of the technique for preferential entry-state population, exit-channel selection, and feeding of the discrete states via selective pathways will be discussed. 20 refs., 4 figs.

Perfluoroisobutylene (PFIB) is an extremely toxic organofluoride that can be produced during pyrolysis of tetrafluoroethylene polymers, including Teflon{reg sign}. Inhalation of PFIB at very low concentrations causes acute lung injury, the hallmark of which is pulmonary edema. Several lines of evidence have suggested that hydrolysis of PFIB and resulting production of hydrofluoric acid may be responsible for pulmonary damage. In order to investigate the potential involvement of hydrofluoric acid in producing lung injury and its relationship to the mechanism of fluorocarbon toxicity, we have compared the pulmonary injury produced by PFIB, by dissociated (H{sup +} and F{sup {minus}}), and by undissociated (HF) hydrofluoric acid in the deep lung. By delivering hydrofluoric acid by intratracheal instillation in neutral buffer, we demonstrate that F{sup {minus}} produces no significant pulmonary injury as assessed by increased in lung weight and ultrastructural changes. Similarly, instillation of acid buffer alone demonstrated that H{sup +} did not produce detectable lung injury. Instillation of HF produced changes in lung weight and ultrastructure similar to those observed in PFIB-treated rats. However, the ultrastructural studies show that in contrast to inhalation of PFIB, which produces both endothelial and epithelial cell damage, instillation of HF appears to exert its injurious effects …

A weekly student newspaper from the Rice University in Houston, Texas that includes campus news and commentaries along with advertising.

A variety of experiments have been performed on the TFTR tokamak utilizing ICFR heating. Of special interest has been the insight into plasma performance gained by utilizing a different heating scheme other than the usual NBI. Utilizing ICRF heating allows control over the power deposition profile independent of the plasma fueling profile. In addition, by varying the minority concentration the power split between ion and electron heating can be varied. Confinement has been examined in high recycling gas fueled discharges, low recycling supershot plasmas, and peaked density pellet fueled discharges. Global confinement is found not to be affected by the method or localization of plasma heating, but the calculated local diffusivities vary with the power deposition profile to yield similar local values. In addition, sawtooth stabilization observed with ICRF heating has been investigated and found to occur in qualitative agreement with theory. ICRF sawtooth stabilized discharges exhibit peaked temperature and density profiles and have a safety factor q which appears to fall well below unity on axis. 11 refs., 10 figs.

In situ fluid operations were conducted at VC-2B in January 1990 using two flow-through tools of different designs. Of eight attempts, no runs obtained samples from their intended depth of collection or, if they did, the tools gained additional fluid by inward leakage during their trips back to the surface. Interpretation of the salinity and mass of the fluid samples indicates that they were collected from apparent depths of about 204 to 1045 m, at collection temperatures of about 125{degree} to 240{degree}C. The data show a remarkable two-fold increase in fluid salinity (>9000 versus about 4000 mg/kg Cl) near the top of the well and a relatively thin, dilute cap'' of condensed steam at the top of the water column. Various criteria suggest that these salinity gradients are caused by boiling and condensation of steam in the wellbore during a seven month period of logging, stimulation, flow testing, and other in-hole experiments. 8 refs., 3 figs., 5 tabs.