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Modeling human risk: Cell & molecular biology in context

Description: It is anticipated that early in the next century manned missions into outer space will occur, with a mission to Mars scheduled between 2015 and 2020. However, before such missions can be undertaken, a realistic estimation of the potential risks to the flight crews is required. One of the uncertainties remaining in this risk estimation is that posed by the effects of exposure to the radiation environment of outer space. Although the composition of this environment is fairly well understood, the biological effects arising from exposure to it are not. The reasons for this are three-fold: (1) A small but highly significant component of the radiation spectrum in outer space consists of highly charged, high energy (HZE) particles which are not routinely experienced on earth, and for which there are insufficient data on biological effects; (2) Most studies on the biological effects of radiation to date have been high-dose, high dose-rate, whereas in space, with the exception of solar particle events, radiation exposures will be low-dose, low dose-rate; (3) Although it has been established that the virtual absence of gravity in space has a profound effect on human physiology, it is not clear whether these effects will act synergistically with those of radiation exposure. A select panel will evaluate the utilizing experiments and models to accurately predict the risks associated with exposure to HZE particles. Topics of research include cellular and tissue response, health effects associated with radiation damage, model animal systems, and critical markers of Radiation response.
Date: June 1, 1997
Partner: UNT Libraries Government Documents Department

The Thermal Expansion of Synthetic Graphites at Temperature Intervals Between 80 and 2000f

Description: The mean linear and cubical coefficients of thermal expansion of eight commercial samples of graphite were determined for temperature intervals between 80 and 2000 deg F. The linear thermal expansion was measured with an automatic recording dilatometer using a rod-shaped specimen 2 in. long and 1/4 in. across. The specimen was heated in an atmosphere of helium. The results were in good agreement with those of Currie, Hamister, and MacPherson. The mean linear coefficient was found to increase with temperature. For the samples studied, the mean linear coefficients from 80 to 2000 deg F were 1.50 to 2.34 x 10/sup -6// deg F parallel and 2.26 to 3.45 x 10/sup -6// deg F perpendicular to the grain and were found to vary linearly with the electrical resistivity measured at 32 deg F. (auth)
Date: November 30, 1959
Creator: Allen, R. D.
Partner: UNT Libraries Government Documents Department

Global and Regional Ecosystem Modeling: Databases of Model Drivers and Validation Measurements

Description: Understanding global-scale ecosystem responses to changing environmental conditions is important both as a scientific question and as the basis for making policy decisions. The confidence in regional models depends on how well the field data used to develop the model represent the region of interest, how well the environmental model driving variables (e.g., vegetation type, climate, and soils associated with a site used to parameterize ecosystem models) represent the region of interest, and how well regional model predictions agree with observed data for the region. To assess the accuracy of global model forecasts of terrestrial carbon cycling, two Ecosystem Model-Data Intercomparison (EMDI) workshops were held (December 1999 and April 2001). The workshops included 17 biogeochemical, satellite-driven, detailed process, and dynamic vegetation global model types. The approach was to run regional or global versions of the models for sites with net primary productivity (NPP) measurements (i.e., not fine-tuned for specific site conditions) and analyze the model-data differences. Extensive worldwide NPP data were assembled with model driver data, including vegetation, climate, and soils data, to perform the intercomparison. This report describes the compilation of NPP estimates for 2,523 sites and 5,164 0.5{sup o}-grid cells under the Global Primary Production Data Initiative (GPPDI) and the results of the EMDI review and outlier analysis that produced a refined set of NPP estimates and model driver data. The EMDI process resulted in 81 Class A sites, 933 Class B sites, and 3,855 Class C cells derived from the original synthesis of NPP measurements and associated driver data. Class A sites represent well-documented study sites that have complete aboveground and below ground NPP measurements. Class B sites represent more numerous ''extensive'' sites with less documentation and site-specific information available. Class C cells represent estimates of NPP for 0.5{sup o}-grid cells for which inventory, modeling, or remote-sensing ...
Date: March 19, 2002
Creator: Olson, R.J.
Partner: UNT Libraries Government Documents Department

Investigations of Pressure Distribution on Fast Flying Bodies

Description: The question to be treated is: how high is the pressure in the bow wave caused by a body flying at supersonic speed, and how far reaching are the destructive effects of that wave? The pressure distribution on an s.S. and an S. projectile of normal speed has been ascertained already by the methods of measurement used at the Ballistic Institute of the Technical Academy of the German Air Forces. Now similar investigations of the conditions on especially fast-flying bodies were carried out.
Date: September 1, 1946
Creator: Stamm, G.
Partner: UNT Libraries Government Documents Department

Suggestions for popularizing civil aviation

Description: The public generally is taking very little interest in the progress of Civil Aviation, and the time has come to educate the public in aeronautics and to make them realize the far-reaching importance of air transport. Briefly, the whole problem resolves itself into discovering and applying means for bringing some of the many aspects and effects of civil aviation into the everyday lives of the public. The report suggests three principal groups of methods: (1) Bring aviation into daily contact with the public. (2) Bring the public into daily contact with aviation. (3) General publicity.
Date: January 1926
Creator: Eliott-Lynn
Partner: UNT Libraries Government Documents Department

Angular signatures, and a space-borne measurement concept

Description: The nature and value of angular signatures in remote sensing are reviewed with emphasis on the canopy hot-spot as a directionally localized angular signature and an important special case of a BRDF (bidirectional reflectance distribution function). A new concept is presented that allows hot spot measurements from space by using active (laser) illumination and bistatic detection. The detectors are proposed as imaging array sensors that are circulating the illumination source (or vice versa) and are connected with it through tethers in space which also provide the directional controls needed so that the entire system becomes pointable like a search light. Near infrared or IR operation in an atmospheric transmission winodw is envisioned with night-time data acquistion. Detailed feasibility and systems analyses have yet to be performed.
Date: May 1, 1996
Creator: Gerstl, S.A.W.
Partner: UNT Libraries Government Documents Department

New perspectives on substorm injections

Description: There has been significant progress in understanding substorm injections since the Third International Conference on Substorms in 1996. Progress has come from a combination of new theories, quantitative modeling, and observations--particularly multi-satellite observations. There is now mounting evidence that fast convective flows are the mechanism that directly couples substorm processes in the mid tail, where reconnection occurs, with substorm processes the inner magnetosphere where Pi2 pulsations, auroral breakups, and substorm injections occur. This paper presents evidence that those flows combined with an earthward-propagating compressional wave are responsible for substorm injections and discusses how that model can account for various substorm injection signatures.
Date: December 1, 1998
Creator: Reeves, G.D.
Partner: UNT Libraries Government Documents Department

Applying lessons learned to enhance human performance and reduce human error for ISS operations

Description: A major component of reliability, safety, and mission success for space missions is ensuring that the humans involved (flight crew, ground crew, mission control, etc.) perform their tasks and functions as required. This includes compliance with training and procedures during normal conditions, and successful compensation when malfunctions or unexpected conditions occur. A very significant issue that affects human performance in space flight is human error. Human errors can invalidate carefully designed equipment and procedures. If certain errors combine with equipment failures or design flaws, mission failure or loss of life can occur. The control of human error during operation of the International Space Station (ISS) will be critical to the overall success of the program. As experience from Mir operations has shown, human performance plays a vital role in the success or failure of long duration space missions. The Department of Energy`s Idaho National Engineering and Environmental Laboratory (INEEL) is developed a systematic approach to enhance human performance and reduce human errors for ISS operations. This approach is based on the systematic identification and evaluation of lessons learned from past space missions such as Mir to enhance the design and operation of ISS. This paper describes previous INEEL research on human error sponsored by NASA and how it can be applied to enhance human reliability for ISS.
Date: September 1, 1998
Creator: Nelson, W.R.
Partner: UNT Libraries Government Documents Department

Nonlinear spectral mixing theory to model multispectral signatures

Description: Nonlinear spectral mixing occurs due to multiple reflections and transmissions between discrete surfaces, e.g. leaves or facets of a rough surface. The radiosity method is an energy conserving computational method used in thermal engineering and it models nonlinear spectral mixing realistically and accurately. In contrast to the radiative transfer method the radiosity method takes into account the discreteness of the scattering surfaces (e.g. exact location, orientation and shape) such as leaves and includes mutual shading between them. An analytic radiosity-based scattering model for vegetation was developed and used to compute vegetation indices for various configurations. The leaf reflectance and transmittance was modeled using the PROSPECT model for various amounts of water, chlorophyll and variable leaf structure. The soil background was modeled using SOILSPEC with a linear mixture of reflectances of sand, clay and peat. A neural network and a geometry based retrieval scheme were used to retrieve leaf area index and chlorophyll concentration for dense canopies. Only simulated canopy reflectances in the 6 visible through short wave IR Landsat TM channels were used. The authors used an empirical function to compute the signal-to-noise ratio of a retrieved quantity.
Date: February 1, 1996
Creator: Borel, C.C.
Partner: UNT Libraries Government Documents Department

Studies of modern and ancient solar energetic particles

Description: Modern solar energetic particles (SEPs) have been studied for about 50 years by satellites and ground-based observations. These measurements indicate much about the nature of SEPs but cover too short a period to quantify the probabilities of very large solar particle events. Many SEPs have high enough energies to make nuclides in material in which they interact. Some nuclides measured in lunar samples have been used to extend the record about SEPs back several million years. Some new measurements of modern SEPs during the last solar cycle and new results for nuclides made by SEPs in lunar samples are presented and their implications discussed. Both the modern and ancient records need to be improved, and methods to get a better understanding of solar energetic particles are discussed. The SEP average fluxes from both sets of records are similar, and both sets can be used to show that huge fluxes of SEPs are very rare.
Date: October 1, 1998
Creator: Reedy, R.C.
Partner: UNT Libraries Government Documents Department

A measurement concept for hot-spot BRDFs from space

Description: Several concepts for canopy hot-spot measurements from space have been investigated. The most promising involves active illumination and bistatic detection that would allow hot-spot angular distribution (BRDF) measurements from space in a search-light mode. The concept includes a pointable illumination source, such as a laser operating at an atmospheric window wavelength, coupled with a number of high spatial-resolution detectors that are clustered around the illumination source in space, receiving photons nearly coaxial with the reto-reflection direction. Microwave control and command among the satellite cluster would allow orienting the direction of the laser beam as well as the focusing detectors simultaneously so that the coupled system can function like a search light with almost unlimited pointing capabilities. The concept is called the Hot-Spot Search-Light (HSSL) satellite. A nominal satellite altitude of 600 km will allow hot-spot BRDF measurements out to about 18 degrees phase angle. The distributed are taking radiometric measurements of the intensity wings of the hot-spot angular distribution without the need for complex imaging detectors. The system can be operated at night for increased signal-to-noise ratio. This way the hot-spot angular signatures can be quantified and parameterized in sufficient detail to extract the biophysical information content of plant architectures.
Date: September 1, 1996
Creator: Gerstl, S.A.W.
Partner: UNT Libraries Government Documents Department

Delta Scuti stars: Theory

Description: The purpose of asteroseismology is not only to derive the internal structure of individual stars from their observed oscillation frequencies, but also to test and extend one`s understanding of the physics of matter under the extremes of temperature, density, and pressure found in stellar interiors. In this review, the author hopes to point out what one can learn about the Sun by studying {delta} Scuti stars, as well as what one can learn about stars more massive or evolved than the Sun. He discusses some of the difficulties in theoretical approaches to asteroseismology for {delta} Scuti stars, using FG Vir, {delta} Scuti, and CD-24{degree} 7599 as examples.
Date: March 1, 1998
Creator: Guzik, J.A.
Partner: UNT Libraries Government Documents Department

Variable White Dwarf Data Tables

Description: Below, I give a brief explanation of the information in these tables. In all cases, I list the WD {number_sign}, either from the catalog of McCook {ampersand} Sion (1987) or determined by me from the epoch 1950 coordinates. Next, I list the most commonly used name (or alias), then I list the variable star designation if it is available. If not, I list the constellation name and a V** or?? depending on what the last designated variable star for that constellation is. I present epoch 2000 coordinates for all of the stars, which I precessed from the 1950 ones in most cases. I do not include proper motion effects; this is negligible for all except the largest proper motion DAV stars, such as L 19-2, BPM 37093, B 808, and G 29-38. Even in these cases, the error is no more than 30` in declination and 2 s in right ascension. I culled effective temperatures from the latest work (listed under each table); they are now much more homogeneous than before. I pulled the magnitude estimates from the appropriate paper, and they are mean values integrated over several cycles. The amplitude given is for the height of a typical pulse in the light curve. The periods correspond the dominant ones found in the light curve. In some cases, there is a band of power in a given period range, or the light curve is very complex, and I indicate this in the table. In the references, I generally list the paper with the most comprehensive pulsation analysis for the star in question. In some cases, there is more than one good reference, and I list them as well.
Date: December 31, 1997
Creator: Bradley, P. A.
Partner: UNT Libraries Government Documents Department

Advanced turbine technology applications project (ATTAP): Hybrid vehicle turbine engine technology support (HVTE-TS): Annual report, 1993-1994

Description: This is the sixth of a series of reports documenting work performed on the ATTAP/HVTETS. This is a combined report to cover work performed in both 1993 and 1994. Progress is reported on ceramic component design and characterization, powertrain development, component rig testing and performance and durability testing.
Date: March 1996
Partner: UNT Libraries Government Documents Department

High Temperature Surface Measurements Using Lifetime Imaging of Thermographic Phosphors: Bonding Tests

Description: Temperature-sensitive paint (TSP) comprised of thermally sensitive phosphor can provide a viable means for noncontact thermometry in wind tunnel and other aeropropulsion applications. Described here are recent results aimed at developing a phosphor and binder system that will cover a wide temperature range, ambient to 1000 C. The phosphor/binder mixture is to be sprayed directly on the surface with an airbrush. Whereas many surfaces are candidates for various uses, the present effort concerned silicon carbide, silicon nitride and silica substrates. Initial tests show that a phosphor mixture with two water-soluble materials, designated LK and HPC and manufactured by ZYP Inc., adhered well to these substrates. This same material was earlier shown to function well on a high strength nickel alloy.
Date: October 29, 2001
Creator: Allison, S. W.
Partner: UNT Libraries Government Documents Department

Advanced far infrared detector and double donor studies in Ge

Description: This has application to astronomy and astrophysics. Selenium in Ge has been studied with a doping technique which limits complex formation. Only one ionization level has been found to correspond to selenium, which presumably occupies a substitutional site. This level is extremely unstable and its concentration decreases after annealing at 400C. Future work is planned to anneal the fast neutron damage before much selenium has formed in the {sup 74/76}Ge samples. It is expected that the observed selenium level can be better characterized and the missing selenium level is more likely to be discovered if other defects are removed before {sup 77}Se formation.
Date: December 1, 1994
Creator: Olsen, C.S.
Partner: UNT Libraries Government Documents Department

Asteroseismology of DAV White Dwarf Stars

Description: The author reviews the seismological structural determinations of ZZ Ceti stars done to date, and supplement these with additional preliminary determinations of his own. He compares the constraints on the hydrogen layer mass to see what trends emerge and also determines if the observed hydrogen layer masses are consistent with proposed theories. He then looks ahead to the prospects of further DAV white dwarf seismology.
Date: December 31, 1997
Creator: Bradley, Paul A.
Partner: UNT Libraries Government Documents Department

Seismological procedures for ZZ Ceti stars and an application to G 117-B15A

Description: In this paper, we outline the procedure for seismological analysis of the ZZ Ceti stars, which are pulsating white dwarfs with hydrogen atmospheres. We use G 117-B15A as the example for this process and derive constraints on the mass and internal structure. The hydrogen layer mass is either about 10(-4)M* or 10(-7)M* depending on whether the l = 1 mode near 215 s is k = 2 or k = 1, respectively. In both cases, the best fitting mass is 0.60M solar, in agreement with spectroscopic log g values.
Date: June 1, 1997
Creator: Bradley, P.A.
Partner: UNT Libraries Government Documents Department

Advanced far infrared blocked impurity band detectors based on germanium liquid phase epitaxy

Description: This research has shown that epilayers with residual impurity concentrations of 5 x 10{sup 13} cm{sup {minus}3} can be grown by producing the purest Pb available in the world. These epilayers have extremely low minority acceptor concentrations, which is ideal for fabrication of IR absorbing layers. The Pb LPE growth of Ge also has the advantageous property of gettering Cu from the epilayer and the substrate. Epilayers have been grown with intentional Sb doping for IR absorption on lightly doped substrates. This research has proven that properly working Ge BIB detectors can be fabricated from the liquid phase as long as pure enough solvents are available. The detectors have responded at proper wavelengths when reversed biased even though the response did not quite reach minimum wavenumbers. Optimization of the Sb doping concentration should further decrease the photoionization energy of these detectors. Ge BIB detectors have been fabricated that respond to 60 cm{sup {minus}1} with low responsivity. Through reduction of the minority residual impurities, detector performance has reached responsivities of 1 A/W. These detectors have exhibited quantum efficiency and NEP values that rival conventional photoconductors and are expected to provide a much more sensitive tool for new scientific discoveries in a number of fields, including solid state studies, astronomy, and cosmology.
Date: May 1, 1998
Creator: Olsen, C.S.
Partner: UNT Libraries Government Documents Department

Advanced Turbine Technology Applications Project (ATTAP). 1944 Annual report

Description: This report summarizes work performed in development and demonstration of structural ceramics technology for automotive gas turbine engines. At the end of this period, the project name was changed to ``Ceramic Turbine Engine Demonstration Project``, effective Jan. 1995. Objectives are to provide early field experience demonstrating the reliability and durability of ceramic components in a modified, available gas turbine engine application, and to scale up and improve the manufacturing processes for ceramic turbine engine components and demonstrate the application of these processes in the production environment. The 1994 ATTAP activities emphasized demonstration and refinement of the ceramic turbine nozzles in the AlliedSignal/Garrett Model 331-200[CT] engine test bed in preparation for field testing; improvements in understanding the vibration characteristics of the ceramic turbine blades; improvements in critical ceramics technologies; and scaleup of the process used to manufacture ceramic turbine components.
Date: June 1995
Partner: UNT Libraries Government Documents Department

Proceedings of the fourth international conference and exhibition: World Congress on superconductivity. Volume 1

Description: The goals of the World Congress on Superconductivity (WCS) have been to establish and foster the development and commercial application of superconductivity technology on a global scale by providing a non-adversarial, non-advocacy forum where scientists, engineers, businessmen and government personnel can freely exchange information and ideas on recent developments and directions for the future of superconductive research. Sessions were held on: accelerator technology, power and energy, persistent magnetic fields, performance characterization, physical properties, fabrication methodology, superconductive magnetic energy storage (SMES), thin films, high temperature materials, device applications, wire fabrication, and granular superconductors. Individual papers are indexed separately.
Date: December 31, 1994
Creator: Krishen, K. & Burnham, C.
Partner: UNT Libraries Government Documents Department

Proceedings of the fourth international conference and exhibition: World Congress on superconductivity. Volume 2

Description: This document contains papers presented at the 4th International Conference Exhibition: World Congress on Superconductivity held at the Marriott Orlando World Center, Orlando, Florida, June 27--July 1, 1994. This conference encompassed research, technology, applications, funding, political, and social aspects of superconductivity. Specifically, the areas of research, technology, and development covered during the conference included high-temperature materials, thin films, C-60 based superconductors, persistent magnetic fields and shielding, fabrication methodology, space applications, physical applications, performance characterization, device applications, weak link effects and flux motion, accelerator technology, superconductivity energy, storage, future research and development directions, medical applications, granular superconductors, wire fabrication technology, computer applications, technical and commercial challenges, and power and energy applications. The key objective of this conference was to provide a forum for the world community to share technological results of recent advances made in the field of superconductivity and to discuss translation of the research to technology which will benefit humanity. More than 150 presentations were made at this conference. Individual papers are indexed separately on the Energy Data Bases.
Date: December 31, 1994
Creator: Krishen, K. & Burnham, C.
Partner: UNT Libraries Government Documents Department

Production systematics of cosmogenic nuclides in the earth

Description: The high-energy particles in the galactic cosmic rays, (GCR) can produce nuclides deep in any object exposed to them. These cosmic-ray-produced (cosmogenic) nuclides have been extensively studied during the last four decades, mainly in meteorites and lunar samples (e.g., 1,2). In extraterrestrial matter, several approaches have been used to determine the production systematics of these cosmogenic nuclides. Production rates of most cosmogenic nuclides in the Earth axe much lower, especially those nuclides made ``in situ`` in the Earth`s surface. Many of these @trial cosmogenic nuclides are only now being measured because of improved techniques, such as accelerator mass spectrometry (AMS). There have been very few determinations of the production rates of nuclides made in the Earth by cosmic rays. The work being done for terrestrial cosmogenic nuclides is following the approaches used for, studying the production of extraterrestrial nuclides.
Date: January 1, 1995
Creator: Reedy, R.C.
Partner: UNT Libraries Government Documents Department