Article discussing a cross-sectional survey study of Hispanic physicians' tobacco intervention practices.

Article on simvastatin sensitizes human gastric cancer xenograft in nude mice to capecitabine by suppressing nuclear factor-kappa B-regulated gene products.

It is well known that the NMR method for protein structure determination applies to small proteins and that its effectiveness decreases very rapidly as the molecular weight increases beyond about 30 kD. We have recently developed a method for protein structure determination that can fully utilize partial NMR data as calculation constraints. The core of the method is a threading algorithm that guarantees to find a globally optimal alignment between a query sequence and a template structure, under distance constraints specified by NMR/NOE data. Our preliminary tests have demonstrated that a small number of NMR/NOE distance restraints can significantly improve threading performance in both fold recognition and threading-alignment accuracy, and can possibly extend threading's scope of applicability from structural homologs to structural analogs. An accurate backbone structure generated by NMR-constrained threading can then provide a significant amount of structural information, equivalent to that provided by the NMR method with many NMR/NOE restraints; and hence can greatly reduce the amount of NMR data typically required for accurate structure determination. Our preliminary study suggests that a small number of NMR/NOE restraints may suffice to determine adequately the all-atom structure when those restraints are incorporated in a procedure combining threading, modeling of loops …

As environmental laws become increasingly protective, and with possible future changes in global climate, thermal effects on aquatic resources are likely to receive increasing attention. Lethal temperatures for a variety of species have been determined for situations where temperatures rise rapidly resulting in lethal effects. However, less is known about the effects of chronic exposure to high (but not immediately lethal) temperatures and even less about stress accumulation during periods of fluctuating temperatures. In this paper we present a modeling framework for assessing cumulative thermal stress in fish. The model assumes that stress accumulation occurs above a threshold temperature at a rate depending on the degree to which the threshold is exceeded. The model also includes stress recovery (or alleviation) when temperatures drop below the threshold temperature as in systems with large daily variation. In addition to non-specific physiological stress, the model also simulates thermal effects on growth.

The Oak Ridge National Laboratory (ORNL) is ''bringing science to life'' through the creation of knowledge; the invention of new tools and techniques; the scientific analysis of complex situations; and the design, construction and operation of research facilities used by scientists and engineers from throughout the world. ORNL creates and uses partnerships as a means for conducting collaborative research and development (R and D), facilitating access to its capabilities, improving the utilization of its unique science and technological facilities, and assisting in commercialization of technology. This paper will concentrate on seven of the mechanisms used to access ORNL facilities and expertise namely, Cooperative Research and Development Agreements, License Agreements, Personnel Exchanges, Small Business Innovative Research and Small Business Technology Transfer Partnerships, Technical Assistance Program, User Facility Agreements, and Work For Others Agreements. Cooperative Research and Development Agreements, also known as CRADAs, create formal teams of researchers from ORNL and private industry for the purpose of collaborating on an R and D area of interest to both partners. License Agreements give commercial entities authorization to use ORNL-developed technologies for specified purposes. A Personnel Exchange either locates ORNL employees at the site of the partner organization, or, brings the employee(s) of the …

The Spallation Neutron Source (SNS) will provide an intense source of low-energy neutrons for experimental use. The low-energy neutrons are produced by the interaction of a high-energy (1.0 GeV) proton beam on a mercury (Hg) target and slowed down in liquid hydrogen or light water moderators. Computer codes and computational techniques are being benchmarked against relevant experimental data to validate and verify the tools being used to predict the performance of the SNS. The LAHET Code System (LCS), which includes LAHET, HTAPE ad HMCNP (a modified version of MCNP version 3b), have been applied to the analysis of experiments that were conducted in the Alternating Gradient Synchrotron (AGS) facility at Brookhaven National Laboratory (BNL). In the AGS experiments, foils of various materials were placed around a mercury-filled stainless steel cylinder, which was bombarded with protons at 1.6 GeV. Neutrons created in the mercury target, activated the foils. Activities of the relevant isotopes were accurately measured and compared with calculated predictions. Measurements at BNL were provided in part by collaborating scientists from JAERI as part of the AGS Spallation Target Experiment (ASTE) collaboration. To date, calculations have shown good agreement with measurements.

This paper summarizes results of Spallation Neutron Source calculations to estimate radiation hazards and shielding requirements for activated Mercury, target components, target cooling water, and {sup 7}Be plateout. Dose rates in the accelerator tunnel from activation of magnets and concrete were investigated. The impact of gaps and other streaming paths on the radiation environment inside the test cell during operation and after shutdown were also assessed.

We report results from three distinct but related thrusts that aim to elucidate the atomic-scale structure and properties of the Sic-SiO{sub 2} interface. (a) First-principles theoretical calculations probe the global bonding arrangements and the local processes during oxidation; (b) Z-contrast atomic-resolution transmission electron microscopy and electron-energy-loss spectroscopy provide images and interface spectra, and (c) nuclear techniques and electrical measurements are used to profile N at the interface and determine interface trap densities.

Transient and static cavitation thresholds for mercury as a function of the cover gas (helium or air), and pressure are reported. Both static and transient cavitation onset pressure thresholds increase linearly with cover gas pressure. Additionally, the cavitation thresholds as a function of dissolved gases were also measured and are reported.

THERE ARE ONLY A FEW OTHER HIGH ENERGY PARTICLE ACCELERATORS LIKE RHIC IN THE WORLD. THEREFORE, THE DESIGNERS OF THE MACHINE DO NOT ALWAYS HAVE CONSENSUS DESIGN STANDARDS AND REGULATORY GUIDANCE AVAILABLE TO ESTABLISH THE ENGINEERING PARAMETERS FOR SAFETY. SOME OF THE AREAS WHERE STANDARDS ARE NOT AVAILABLE RELATE TO THE CRYOGENIC SYSTEM, CONTAINMENT OF LARGE VOLUMES OF FLAMMABLE GAS IN FRAGILE VESSELS IN THE EXPERIMENTAL APPARATUS AND MITIGATION OF A DESIGN BASIS ACCIDENT WITH A STORED PARTICLE BEAM. UNIQUE BUT EQUIVALENT SAFETY ENGINEERING MUST BE DETERMINED. SPECIAL DESIGN CRITERIA FOR PROMPT RADIATION WERE DEVELOPED TO PROVIDE GUIDANCE FOR THE DESIGN OF RADIATION SHIELDING.

The Spherical Torus (ST) configuration has recently emerged as an example of confinement concept innovation that enables attractive steps in the development of fusion energy. The scientific potential for the ST has been indicated by recent encouraging results from START,2 CDX-U, and HIT. The scientific principles for the D-fueled ST will soon be tested by NSTX (National Spherical Torus Experiment3) in the U.S. and MAST (Mega-Amp Spherical Tokamak4) in the U.K. at the level of l-2 MA in plasma current. More recently, interest has grown in the U.S. in the possibility of near-term ST fusion burn devices at the level of 10 MA in plasma current. The missions for these devices would be to test burning plasma performance in a small, pulsed D-T-fueled ST (i.e., DTST) and to develop fusion energy technologies in a small steady state ST-based Volume Neutron Source (VNS). This paper reports the results of analysis of the key science and technology issues for these devices.

Experimental studies involving equilibrium solubility and dissolution/precipitation rates were initiated on boehmite (AIOOH) using a hydrogen-electrode concentration cell (HECC). This cell provides continuous, accurate in situ pH measurements of solid/solution mixtures to 295 C with provision for either removing solution samples for analysis of the metal content, or adding either of two titrants. This cell has been recently used to measure the solubility of minerals such as brucite; boehmite, zincite, arid magnetite. The ability to perturb pH, isothermally by addition of acidic or basic titrant opens the door for studies of the kinetics of dissolution/precipitation, even for relatively fast reactions. By monitoring the change in pH, with time, detailed kinetic information can be obtained without the need for sampling.

Radiocesium is one of the more prevalent radionuclides in the environment as a result of weapons production related atomic projects in the United States and the former Soviet Union. Radiocesium discharges during the 1950's account for a large fraction of the historical releases from U.S. weapons production facilities. Releases of radiocesium to terrestrial and aquatic ecosystems during the early ,years of nuclear weapons production provided the opportunity to conduct multidisciplinary studies on the transport mechanisms of this potentially hazardous radionuclide. The major U.S. Department of Energy facilities (Oak Ridge Reservation in Tennessee, Hanford Site near Richland, Washington, and Savannah River Site near Aiken, South Carolina) are located in regions of the country that have different geographical characteristics. The facility siting provided diverse backgrounds for the development of an understanding of environmental factors contributing to the fate and transport of radiocesium. In this paper, we summarize the significant environmental releases of radiocesium in the early -years of weapons production and then discuss the historically significant transport mechanisms for r37Cs at the three facilities that were part of the U.S. nuclear weapons complex.

Calculations of the gamma dose rates inside and outside of the Target Service Cell (TSC) of the Spallation Neutron Source (SNS) are complicated by the large size of the structure, large volume of air (internal void), optical thickness of the enclosing walls, and multiplicity of radiation sources. Furthermore, a reasonably detailed distribution of the dose rate over the volume of the TSC, and on the outside of its walls is necessary in order to optimize electronic instrument locations, and plan access control. For all these reasons a deterministic transport method was preferred over Monte Carlo, The three- dimensional neutral particle transport code TORT was employed for this purpose with support from other peripheral codes in the Discrete Ordinates of Oak Ridge System (DOORS). The computational model for the TSC is described and the features of TORT and its companion codes that enable such a difficult calculation are discussed. Most prominent is the presence of severe ray effects in the air cavity of the TSC that persists in the transport through the concrete walls and is pronounced throughout the problem volume. Initial attempts at eliminating ray effects from the computed results using the newly developed three-dimensional uncollided flux and first collided …

Geophysical data were acquired at a site on the Oak Ridge Reservation, Tennessee to determine the characteristics of a mud-filled void and to evaluate the effectiveness of a suite of geophysical methods at the site. Methods that were used included microgravity, electrical resistivity, and seismic refraction. Both microgravity and resistivity were able to detect the void as well as overlying structural features. The seismic data provide bedrock depth control for the other two methods, and show other effects that are caused by the void.

Experimental and computational thermal-hydraulic research is underway to support the liquid mercury target design for the Spallation Neutron Source (SNS) facility. The SNS target will be subjected to internal nuclear heat generation that results from pulsed proton beam collisions with the mercury nuclei. Recirculation and stagnation zones within the target are of particular concern because of the likelihood that they will result in local hot spots and diminished heat removal from the target structure. Computational fluid dynamics (CFD) models are being used as a part of this research. Recent improvements to the 3D target model include the addition of the flow adapter which joins the inlet/outlet coolant pipes to the target body and an updated heat load distribution at the new baseline proton beam power level of 2 MW. Two thermal-hydraulic experiments are planned to validate the CFD model.

The Measurement Applications and Development Group at the Oak Ridge National Laboratory has used a FIDLER to characterize a site where numerous localized and dispersed concentrations of uranium had been previously discovered beneath a poured concrete floor. The thick floor impeded the evaluation of the distribution of regions containing uranium without boring numerous holes through the concrete. The purpose of this study was to perform a radiological assessment of the building in preparation for remediation of the site. Integrated counts were taken with the FIDLER probes fixed in place on a systematic grid across the area to be evaluated. The results were then superimposed on a drawing of the area of evaluation. This approach allowed the boundaries of the regions with subsurface contamination to be resolved much better than by using standard survey techniques and decreased the number of borehole samples and subsequent analyses. The study demonstrated that this survey technique provides rapid and essential characterization information and reduces sampling, analytical, and remediation costs.

The effects of implanted oxygen on the damage accumulation in sapphire which was previously implanted with iron was studied for (0001) sapphire implanted with iron and then with oxygen. The energies were chosen to give similar projected ranges. One series was implanted with a 1:l ratio (4x10{sup 16} ions/cm{sup 2} each) and another with a ratio of 2:3 (4x10{sup 16} fe{sup +}/cm{sup 2}; 6x10{sup 16} O{sup +}/cm{sup 2}). Retained damage, X, in the Al-sublattice, was compared to that produced by implantation of iron alone. The observed disorder was less for the dual implantations suggesting that implantation of oxygen enhanced dynamic recovery during implantation. Samples were annealed for one hour at 800 and 1200 C in an oxidizing and in a reducing atmosphere. No difference was found in the kinetics of recovery in the Al-sublattice between the two dual implant conditions. However, the rate of recovery was different for each from samples implanted with iron alone.

As a U.S. Department of Energy (DOE) Office of Science (SC) National Laboratory, the Oak Ridge National Lab (ORNL) participates in the Laboratory Technology Research (LTR) Program. The mission of the LTR Program is to advance science and technology, in support of DOE missions, toward innovative applications through cost-shared partnerships with the private sector. The benefits to industry participants include gaining access to world-class researchers and facilities, while the benefits to the ORNL researchers includes leveraging the declining government-provided funds. Thus, the importance placed upon industry partner satisfaction is large, especially if the LTR Program is to be sustained during episodes of government budget constraints. Realizing the critical nature of partner satisfaction, in 1998 the DOE-SC National Laboratories surveyed industrial partners to assess their satisfaction with the cooperative research projects in which they were involved. This paper will describe the survey methodology including development of the questionnaire and a summary of the responses (particularly those which are germane to the ORNL.) The results of the survey will be categorized as follows: (1) Desire to partner again with ORNL; (2) Benefits obtained by the company from the partnership; and (3) LTR Program ratings assigned in 11 key areas (i.e., quality of …

An overview is provided on modeling and analysis of thermal shock experiments conducted during 1998 with high-energy, short-pulse energy deposition in a mercury filled container in the Alternating Gradient Synchrotron (AGS) facility at Brookhaven National Laboratory (BNL). The simulation framework utilized along with the results of simulations for pressure and strain profiles are presented. While the magnitude of penk strain predictions versus data are in reasonable agreement, the temporal variations were found to differ significantly in selected cases, indicating lack of modeling of certain physical phenomena or due to uncertainties in the experimental data gathering techniques. Key thermal-shock related issues and uncertainties are highlighted. Specific experiments conducted at BNL's AGS facility during 1998 (the subject of this paper) involved high-energy (24 GeV) proton energy deposition in the mercury target over a time frame of - 0.1s. The target consisted of an - 1 m. long cylindrical stainless steel shell with a hemispherical dome at the leading edge. It was filled with mercury at room temperature and pressure. Several optical strain gages were attached to the surface of the steel target. Figure 1 shows a schematic representation of the test vessel along with the main dimensions and positions of three optical …

Measurements of fission and capture in {sup 235}U, {sup 238}U, {sup 239}Pu and {sup 237}Np and in their product actinides have been made following irradiation in the metal-fuel core of EBR-II. The reactor has a peak flux around 500keV and the data complement measurements in the softer spectrum of an LMFBR. Irradiations were made at the same time for a set of standard dosimeter samples. These provide a test of calculated spectra and are also used for validation of steel activations and calculated atomic displacement rates. Calculation were made with modem transport codes using ENDF/B-5.2 data. Comparisons are made, using a simple homogeneous model, producing a similar spectrum, using ENDF/B-6.2 and JEFF-2 data.

US transportation regulations require that a Type B package certified for the transport of fissile material be capable of withstanding a series of tests that demonstrate package integrity under hypothetical accident conditions (HAC). These tests, which are similar to those specified in IAEA regulations, include a sequence consisting of (1) a 9-m (30-ft.) free drop onto an unyielding surface, (2) a 1-m (40-in.) free drop onto a mild steel puncture bar, (3) an exposure to a 30-minute fire of at least 800{degrees}C, and (4) an 8-hour immersion in 0.9 m (3 ft.) of water. This paper presents a possible alternative to conducting an 8-hour immersion test. This alternative would be especially attractive in the case where the water immersion requirement arises after the initial test program, but may also support omission of the immersion test for other cases. In previous Safety Analysis Reports for package certification, applicants have sometimes justified ommission of the immersion test by merely asserting that a structurally sound package which passes the drop, puncture, and fire tests will not permit water in leakage. The method discussed in this paper presents an analytical justification for such a conclusion.

A study was undertaken at Lawrence Livermore National Laboratory to characterize uranium, 6% niobium ingots produced via electron beam melting, hearth refining and continuous casting and to compare this material with conventional VIM/skull melt/VAR material. Samples of both the ingot and feed material were analyzed for niobium and trace metallic elements, carbon, oxygen and nitrogen. This material was also inspected metallographically and via microprobe analysis.

The Urals Electrochemical Integrated Plant (UEIP) is the Russian Federation`s largest uranium enrichment plant and one of three sites in Russia blending high enriched uranium (HEU) into commercial grade low enriched uranium. UEIP is located approximately 70 km north of Yekaterinburg in the closed city of Novouralsk (formerly Sverdlovsk- 44). DOE`s MPC&A program first met with UEIP in June of 1996, however because of some contractual issues the work did not start until September of 1997. The six national laboratories participating in DOE`s Material Protection Control and Accounting program are cooperating with UEIP to enhance the capabilities of the physical protection, access control, and nuclear material control and accounting systems. The MPC&A work at UEIP is expected to be completed during fiscal year 2001.