We have systematically studied the thermodynamic stabilities of various phases of the nitrides of the platinum metal elements using density functional theory. We show that for the nitrides of Rh, Pd, Ir and Pt two new crystal structures, in which the metal ions occupy simple tetragonal lattice sites, have lower formation enthalpies at ambient conditions than any previously proposed structures. The region of stability can extend up to 17 GPa for PtN{sub 2}. Furthermore, we show that according to calculations using the local density approximation, these new compounds are also thermodynamically stable at ambient pressure and thus may be the ground state phases for these materials. We further discuss the fact that the local density and generalized gradient approximations predict different values of the absolute formation enthalpies as well different relative stabilities between simple tetragonal and the pyrite or marcasite structures.

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

This report discusses the polar bear status and they are affected by climate change, contaminants, and subsistence and sport hunting.

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

If the collisional time scale for Coulomb collisions is comparable to the characteristic time scales for a plasma, then simulation of Coulomb collisions may be important for computation of kinetic plasma dynamics. This can be a computational bottleneck because of the large number of simulated particles and collisions (or phase-space resolution requirements in continuum algorithms), as well as the wide range of collision rates over the velocity distribution function. This paper considers Monte Carlo simulation of Coulomb collisions using the binary collision models of Takizuka & Abe and Nanbu. It presents a hybrid method for accelerating the computation of Coulomb collisions. The hybrid method represents the velocity distribution function as a combination of a thermal component (a Maxwellian distribution) and a kinetic component (a set of discrete particles). Collisions between particles from the thermal component preserve the Maxwellian; collisions between particles from the kinetic component are performed using the method of or Nanbu. Collisions between the kinetic and thermal components are performed by sampling a particle from the thermal component and selecting a particle from the kinetic component. Particles are also transferred between the two components according to thermalization and dethermalization probabilities, which are functions of phase space.

In this lecture we presented a methodology to obtain free energies from empirical potentials and applied it to the study of the phase diagram of FeCr. Subsequently, we used Metropolis Monte Carlo to analyze homogeneous and heterogeneous precipitation of the Cr rich solid solution {alpha}{prime}. These examples are part of our work in the area of steels for nuclear applications and can be found in several publications of our group cited as References.

Semiweekly newspaper from Boerne, Texas that includes local, state, and national news along with advertising.

Daily newspaper from Baytown, Texas that includes local, state, and national news along with advertising.

A search for charmonium and other new states is performed in a study of exclusive initial-state-radiation production of D{bar D} events from electron-positron annihilations at a center-of-mass energy of 10.58 GeV. The data sample corresponds to an integrated luminosity of 384 fb{sup -1} and was recorded by the BABAR experiment at the PEP-II storage ring. The D{bar D} mass spectrum shows clear evidence of the {psi}(3770) plus other structures near 3.9, 4.1, and 4.4 GeV/c2. No evidence for Y (4260) {yields} D{bar D} is observed, leading to an upper limit of {Beta}(Y (4260) {yields} D{bar D})/{Beta}(Y (4260) {yields} J/{psi}{pi}{sup +}{pi}{sup -}) < 1.0 at 90% confidence level.

Weekly student newspaper from the University of Dallas in Irving, Texas that includes campus news and commentaries along with advertising.

The Gamma-ray Large Area Space Telescope (GLAST) is a next generation high energy gamma-ray observatory due for launch in Fall 2007. The primary instrument is the Large Area Telescope (LAT), which will measure gamma-ray flux and spectra from 20 MeV to > 300 GeV and is a successor to the highly successful EGRET experiment on CGRO. The LAT will have better angular resolution, greater effective area, wider field of view and broader energy coverage than any previous experiment in this energy range. This poster will present performance estimates with particular emphasis on how these apply to studies of microquasars. The LAT's scanning mode will provide unprecedented uniformity of sky coverage and permit measurements of light curves for any source. We will show results from recent detailed simulations that illustrate the potential of the LAT to observe microquasar variability and spectra, including source sensitivity and ability to detect orbital modulation.

None

None

By comparison with thermal neutrons, cold neutrons are attenuated to a greater extent by elements such as H, O, N, B, Cd, Gd and to a leser extent by metals such as Be, Al, Fe, Zr, Sn, W, Bi, Pb. Such unique nuclear properties to interact with materials enable to provide better non-destructive inspections.

Purpose. This study was designed to elucidate the role of amplification at 8q24 in the pathophysiology of ovarian and breast cancer since increased copy number at this locus is one of the most frequent genomic abnormalities in these cancers. Experimental Design. To accomplish this, we assessed the association of amplification at 8q24 with outcome in ovarian cancers using FISH to tissue microarrays and measured responses of ovarian and breast cancer cell lines to specific small interfering RNAs (siRNA) against the oncogene, MYC, and a putative noncoding RNA, PVT1, both of which map to 8q24. Results. Amplification of 8q24 was associated with significantly reduced survival duration. In addition, siRNA-mediated reduction in either PVT1 or MYC expression inhibited proliferation in breast and ovarian cancer cell lines in which they were both amplified and over expressed but not in lines in which they were not amplified/over expressed. Inhibition of PVT1 expression also induced a strong apoptotic response in cell lines in which it was over expressed but not in lines in which it was not amplified/over expressed. Inhibition of MYC, on the other hand, did not induce an apoptotic response in cell lines in which MYC was amplified and over expressed. Conclusions. These …

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

A Lower Hybrid Current Drive (LHCD) system has been installed on the Alcator C-MOD tokamak at MIT. Twelve klystrons at 4.6 GHz feed a 4x22 waveguide array. This system was designed for maximum flexibility in the launched parallel wave-number spectrum. This flexibility allows tailoring of the lower hybrid deposition under a variety of plasma conditions. Power levels up to 900 kW have been injected into the tokomak. The parallel wave number has been varied over a wide range, n|| ~ 1.6–4. Driven currents have been inferred from magnetic measurements by extrapolating to zero loop voltage and by direct comparison to Fisch-Karney theory, yielding an efficiency of n20IR/P ~ 0.3. Modeling using the CQL3D code supports these efficiencies. Sawtooth oscillations vanish, accompanied with peaking of the electron temperature (Te0 rises from 2.8 to 3.8 keV). Central q is inferred to rise above unity from the collapse of the sawtooth inversion radius, indicating off-axis cd as expected. Measurements of non-thermal x-ray and electron cyclotron emission confirm the presence of a significant fast electron population that varies with phase and plasma density. The x-ray emission is observed to be radialy broader than that predicted by simple ray tracing codes. Possible explanations for this …

The present state of the theory of fluctuations in gyrokinetic GK plasmas and especially its application to sampling noise in GK particle-in-cell PIC simulations is reviewed. Topics addressed include the Δf method, the fluctuation-dissipation theorem for both classical and GK many-body plasmas, the Klimontovich formalism, sampling noise in PIC simulations, statistical closure for partial differential equations, the theoretical foundations of spectral balance in the presence of arbitrary noise sources, and the derivation of Kadomtsev-type equations from the general formalism.

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

Ti:sapphire has become the premier lasing medium material for use in solid-state femtosecond high-peak power laser systems because of its wide wavelength tuning range. With a tuneable range from 680 to 1100 nm, peaking at 800 nm, Ti:sapphire lasing crystals can easily be tuned to the required pump wavelength and provide very high pump brightness due to their good beam quality and high output power of typically several watts. Femtosecond lasers are used for precision cutting and machining of materials ranging from steel to tooth enamel to delicate heart tissue and high explosives. These ultra-short pulses are too brief to transfer heat or shock to the material being cut, which means that cutting, drilling, and machining occur with virtually no damage to surrounding material. Furthermore, these lasers can cut with high precision, making hairline cuts of less than 100 microns in thick materials along a computer-generated path. Extension of laser output to higher energies is limited by the size of the amplification medium. Yields of high quality large diameter crystals have been constrained by lattice distortions that may appear in the boule limiting the usable area from which high quality optics can be harvested. Lattice distortions affect the transmitted wavefront …

Interview with Sharon "Tommie" Acierno, Vietnam War veteran, as part of the Tarrant County War Veterans Oral History Project. The interview includes Acierno's personal experiences about childhood, dropping out of high school and enlisting in the U.S. Army, basic and clerical training, working as drill sergeant at Ft. McClellan, struggling with alcoholism and post-traumatic stress disorder, and working with the Vietnam Veterans of America group. Acierno also discusses her coming out experience, volunteering for assignment to Vietnam, her clerical duties with a logistics unit at Long Binh, the camaraderie among gay and straight troops, her experiences with apathetic citizens and antiwar protesters upon return to the U.S., deciding to leave the Army and relocate to Dallas, her experience in the Veterans Administration psychiatric ward, and her opinions regarding the "Don't ask, don't tell" policy and the treatment of women in the military generally. The interview includes an appendix with photographs.

The objective of this report was to create a low-cost, modest-power RF coupler for a SRF spoke cavity beam test of electrons test to be done at LANL. Developing the design for this magnetically-coupled SRF spoke cavity testing coupler was basically straightforward since the cavity coupling port needed to be one of the 1.22-inch ID ports, and the power level was limited by the available RF to less than 400 W TW power. In addition, the coupler would be immersed in bath cryostat filled with liquid helium, and ultimately used in a pulsed mode to accelerate beam, thereby significantly relaxing the thermal loads on the coupler. Combining the above considerations with the level of resources available for this task, emphasis was placed on rapidly developing a robust, reliable design that would use commercially-available components as available to save design, engineering, and fabrication costs. Analysis was also kept to a minimum. As such, the design incorporates the following features: (1) Use of a commercially-available Type-N ceramic feedthrough. For the power and frequency range of the test, with the feedthrough immersed in LHe, it was felt the Type-N feedthrough would provide a robust, low-cost vacuum window solution. (2) The coupler outer conductors …

Diagnosis and management of dust inventories generated in next-step magnetic fusion devices is necessary for their safe operation. A novel electrostatic dust detector, based on a fine grid of interlocking circuit traces biased to 30 or 50 ν has been developed for the detection of dust particles on remote surfaces in air and vacuum environments. Impinging dust particles create a temporary short circuit and the resulting current pulse is recorded by counting electronics. Up to 90% of the particles are ejected from the grid or vaporized suggesting the device may be useful for controlling dust inventories. We report measurements of the sensitivity of a large area (5x5 cm) detector to microgram quantities of dust particles and review its applications to contemporary tokamaks and ITER.

We discuss the contribution of kiloparsec-scale jets in FR I radio galaxies to the diffuse {gamma}-ray background radiation. The analyzed {gamma}-ray emission comes from inverse-Compton scattering of starlight photon fields by the ultrarelativistic electrons whose synchrotron radiation is detected from such sources at radio, optical and X-ray energies. We find that these objects, under the minimum-power hypothesis (corresponding to a magnetic field of 300 {micro}G in the brightest knots of these jets), can contribute about one percent to the extragalactic {gamma}-ray background measured by EGRET. We point out that this result already indicates that the magnetic fields in kpc-scale jets of low-power radio galaxies are not likely to be smaller than 10 {micro}G on average, as otherwise the extragalactic {gamma}-ray background would be overproduced.