The authors report the resonant Raman scattering of the optical phonon in Ge nanocrystals with radius ranging from 2 to 5 nm. They have observed the effect of quantum confinement on both the optical phonon and the E{sub 1} exciton. The confinement energy of the E{sub 1} exciton has been explained within the effective mass approximation.

We present the pressure dependence of the defect emissions in the chalcopyrite alloy semiconductor Ag{sub x}Cu{sub 1-x}GaS{sub 2} for values of the alloy concentration x varying between 0 and 1. A large variation in the pressure coefficients of the different defect emissions with x was found. In one alloy concentration x=0.25 deep levels were found to appear under pressure. Plausible explanations of our results have been proposed.

Raman scattering in the chalcopyrite quaternary alloy Ag{sub x}Cu{sub 1-x}GaS{sub 2} has been studied under high pressure (up to 7 GPa) and at low temperature (50 K) using a diamond anvil high pressure cell for alloy concentrations x=1, 0.75, 0.5, 0.25 and 0. This has allowed us to determine the dependence of their zone-center phonon modes on both pressure and alloy concentration. The resultant phonon pressure coefficients are helpful in understanding the nature of the phonon modes in these chalcopyrites.

The emission at {approx}2.8 eV from heavily doped p-GaN, known as the blue luminescence (BL), has been studied by selective excitation using a dye laser tunable between 2.7-3.0 eV. The peak position and intensity of the BL are found to exhibit an unusual dependence on the excitation photon energy. We have explained our results with a shallow-donor and deep-acceptors pair recombination model which includes potential fluctuations induced by heavy doping. We found a ''critical energy'' of {approx}2.8 eV for the BL. Electron-hole pairs with energies above this energy are able to achieve quasi-thermal equilibrium while those with energies below 2.8 eV are strongly ''localized''.

Photoluminescence upconversion (PLU) is a phenomenon in which a sample emits photons with energy higher than that of the excitation photon. This effect has been observed in many materials including rare earth ions doped in insulating hosts and semiconductor heterostructures without using high power lasers as the excitation source. Recently, this effect has been observed also in partially CuPt-ordered GaInP{sub 2} epilayers grown on GaAs substrates. As a spectroscopic technique photoluminescence upconversion is particularly well suited for studying band alignment at heterojunction interface. The value of band-offset has been determined with meV precision using magneto-photoluminescence. Using the fact that the pressure coefficient of electrons in GaAs is higher than those in GaInP{sub 2} they have been able to manipulate the band-offset at the GaInP/GaAs interface. By converting the band-offset from Type I to Type II they were able to demonstrate that the efficiency of the upconversion process is greatly enhanced by a Type II band-offset.

We discuss the extension of the powerful technique of Thomson scattering to the x-ray regime for providing an independent measure of plasma parameters for dense plasmas. By spectrally-resolving the scattering, the coherent (Rayleigh) unshifted scattering component can be separated from the incoherent Thomson component, which is both Compton and Doppler shifted. The free electron density and temperature can then be inferred from the spectral shape of the high frequency Thomson scattering component. In addition, as the plasma temperature is decreased, the electron velocity distribution as measured by incoherent Thomson scattering will make a transition from the traditional Gaussian Boltzmann distribution to a density-dependent parabolic Fermi distribution to. We also present a discussion for a proof-of-principle experiment appropriate for a high energy laser facility.

This article discusses an analysis of ultraviolet observations with the FAUST shuttle-borne telescope toward the Antennae and NGC 6752 celestial regions resulting in the detection of 46 and 221 candidate sources respectively, for a signal-to-noise ratio of 8.

This article reports on the growth, fabrication, and device characterization of NbN internally shunted Josephson junctions with a TaNx barrier.

Many membrane element manufacturers provide a computer program to aid buyers in the use of their elements. However, to date there are few examples of fully integrated public domain software available for calculating reverse osmosis and nanofiltration system performance. The Total Flux and Scaling Program (TFSP), written for Excel 97 and above, provides designers and operators new tools to predict membrane system performance, including scaling and fouling parameters, for a wide variety of membrane system configurations and feedwaters. The TFSP development was funded under EPA contract 9C-R193-NTSX. It is freely downloadable at www.reverseosmosis.com/download/TFSP.zip. TFSP includes detailed calculations of reverse osmosis and nanofiltration system performance. Of special significance, the program provides scaling calculations for mineral species not normally addressed in commercial programs, including aluminum, iron, and phosphate species. In addition, ASTM calculations for common species such as calcium sulfate (CaSO{sub 4}{times}2H{sub 2}O), BaSO{sub 4}, SrSO{sub 4}, SiO{sub 2}, and LSI are also provided. Scaling calculations in commercial membrane design programs are normally limited to the common minerals and typically follow basic ASTM methods, which are for the most part graphical approaches adapted to curves. In TFSP, the scaling calculations for the less common minerals use subsets of the USGS PHREEQE and …

The nonlinear Poisson-Boltzmann (PB) equation is solved using Pseudo Transient Continuation. The PB solver is constructed by modifying the nonlinear diffusion module of a 3D, massively parallel, unstructured-grid, finite element, radiation-hydrodynamics code. The solver also computes the electrostatic energy and evaluates the force on a user-specified contour. Either Dirichlet or mixed boundary conditions are allowed. The latter specifies surface charges, approximates far-field conditions, or linearizes conditions ''regulating'' the surface charge. The code may be run in either Cartesian, cylindrical, or spherical coordinates. The potential and force due to a conical probe interacting with a flat plate is computed and the result compared with direct force measurements by chemical force microscopy.

We built a bi-directional scatter diagnostics to measure and quantify losses due to scattering and absorption of harmonic conversion crystals (DKDP) for the National Ignition Facility (NIF). The main issues to be addressed are (1) amount of total energy reaching the target if the target hole was {+-}200 {micro}rad in size, (2) distribution of energy inside the target hole, (3) collateral damage of other optics by scattered light. The scatter diagnostics enables angle-resolved measurements at 351 nm, and is capable of both near specular transmission and large angle scatter measurements. In the near specular setup, the transmission can be measured within {+-}65 {micro}rad up to {+-}60 mrad acceptance angle. A silicon photo detector and a scientific-grade CCD camera provide total energy and energy distribution. A linear swing arm detection system enables large angle scatter measurements of 360{sup o}, in principal, with step sizes as small as 0.01{sup o} and different collection angle ranging between 1 and 20 mad. In this paper, scatter effects from laser damage and final finishing process of DKDP are discussed.

We investigated chemical etching as a possible means to mitigate the growth of UV laser-induced surface damage on fused silica. The intent of this work is to examine the growth behavior of existing damage sites that have been processed to remove the UV absorbing, thermo-chemically modified material within the affected area. The study involved chemical etching of laser-induced surface damage sites on fused silica substrates, characterizing the etched sites using scanning electron microscopy (SEM) and laser fluorescence, and testing the growth behavior of the etched sites upon illumination with multiple pulses of 351nm laser light. The results show that damage sites that have been etched to depths greater than about 9 {micro}m have about a 40% chance for zero growth with 1000 shots at fluences of 6.8-9.4 J/cm{sup 2}. For the etched sites that grow, the growth rates are consistent with those for non-etched sites. There is a weak dependence of the total fluorescence emission with the etch depth of a site, but the total fluorescence intensity from an etched site is not well correlated with the propensity of the site to grow. Deep wet etching shows some promise for mitigating damage growth in fused silica, but fluorescence does not …

An interactive Beamline Matching application has been developed using beamline and automatic differentiation class libraries. Various freely available components were used; in particular, the user interface is based on FLTK, a C++ toolkit distributed under the terms of the GNU Public License (GPL). The result is an application that compiles without modifications under both X-Windows and Win32 and offers the same look and feel under both operating environments. In this paper, we discuss some of the practical issues that were confronted and the choices that were made. In particular, we discuss object-based event propagation mechanisms, multithreading, language mixing and persistence.

Article discussing a case study on community and university collaboration in health care planning.

The DOIM (Dense Optical-electrical Interface Modules) is a custom-designed optical data transmission module employed in the upgrade of Silicon Vertex Detector of CDF experiment at Fermilab. Each DOIM module consists of a transmitter (TX) converting electrical differential input signals to optical outputs, a middle segment of jacketed fiber ribbon cable, and a receiver (RX) which senses the light inputs and converts them back to electrical signals. The targeted operational frequency is 53 MHz, and higher rate is achievable. This article outlines the design goals, implementation methods, production test results, and radiation hardness tests of these modules.

The authors report the observation of dijet events with a Double Pomeron Exchange topology produced in {bar p}p collisions at {radical}s = 1,800 GeV. The events are characterized by a leading antiproton, two jets in the central pseudorapidity region, and a rapidity gap on the outgoing proton side. Results on kinematics, production rates, and comparisons with corresponding results from single diffractive and inclusive dijet production are presented.

Double-diffusive finger convection is a hydrodynamic instability that can occur when two components with different diffusivities are oppositely stratified with respect to the fluid density gradient as a critical condition is exceeded. Laboratory experiments were designed using sodium chloride and sucrose solutions in a Hele-Shaw cell. A high resolution, full field, light transmission technique was used to study the development of the instability. The initial buoyancy ratio (R{sub p}), which is a ratio of fluid density contributions by the two solutes, was varied systematically in the experiments so that the range of parameter space spanned conditions that were nearly stable (R{sub p} = 2.8) to those that were moderately unstable (R{sub p} = 1.4). In systems of low R{sub p}, fingers develop within several minutes, merge with adjacent fingers, form conduits, and stall before newer-generated fingers travel through the conduits and continue the process. Solute fluxes in low R{sub p} systems quickly reach steady state and are on the order of 10{sup {minus}6} m{sup 2} sec{sup {minus}1}. In the higher R{sub p} experiments, fingers are slower to evolve and do not interact as dynamically as in the lower R{sub p} systems. Our experiment with initial R{sub p} = 2.8 exhibited …

Article provides an account of the American mindset in the early twentieth century and how human interests dictated the state's early environmental history and the creation of the Wichita Mountains Wildlife Refuge in southwestern Oklahoma.

For the Record section including the minutes of the Quarterly Board Meeting of the Oklahoma Historical Society that was held on July 26, 2000.

An important feature of a {mu}-storage ring {nu}-source is that it can be extended to the possibility of a future high-energy muon collider. The neutrino source provides a useful physics device that initiates key technologies required for future {mu}{sup +}-{mu}{sup {minus}} Colliders, but with much less demanding parameter requirements. These technologies include high-intensity {mu}-production, {mu}-capture, {mu}-cooling, {mu}-acceleration and multiturn {mu} storage rings. {mu}{sup +}-{mu}{sup {minus}} colliders require a similar number of muons, but they require that the muons be cooled to a much smaller phase space and formed into a small number of bunches, and both positive and negative bunches must be simultaneously captured. These differences are discussed, and the extension of the {nu}-source to {mu}{sup +}-{mu}{sup {minus}} collider specifications is described.

Article delineates the fascination H. L. Mencken, influential social critic, journalist, and editor, had with Oklahoma-centered literature and poetry. Lawrence R. Rodgers discusses the works of several writers the critic openly supported. Many of these writers had an affiliation with the University of Oklahoma.

An experimental investigation was conducted to study double-diffusive finger convection in a Hele-Shaw cell by layering a sucrose solution over a more-dense sodium chloride (NaCl) solution. The solutal Rayleigh numbers were on the order of 60,000, based upon the height of the cell (25 cm), and the buoyancy ratio was 1.2. A full-field light transmission technique was used to measure a dye tracer dissolved in the NaCl solution. They analyze the concentration fields to yield the temporal evolution of length scales associated with the vertical and horizontal finger structure as well as the mass flux. These measures show a rapid progression through two early stages to a mature stage and finally a rundown period where mass flux decays rapidly. The data are useful for the development and evaluation of numerical simulators designed to model diffusion and convection of multiple components in porous media. The results are useful for correct formulation at both the process scale (the scale of the experiment) and effective scale (where the lab-scale processes are averaged-up to produce averaged parameters). A fundamental understanding of the fine-scale dynamics of double-diffusive finger convection is necessary in order to successfully parameterize large-scale systems.

Article describes the life and political career of William "Alfalfa Bill" Murray and his efforts to promote free access to education and textbooks in the Oklahoma public school system. Karen McKellips illuminates the contrast between his progressive political and economic views on reform and his support of racial segregation.

Article attempting to show that the sequence of a typical near-death experience (NDE) is predictable and reproducible, enough to suggest that the NDE is a symptom of a specific altered mental state seen in a large number of medical and surgical conditions.