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GAO Performance and Accountability Highlights: Fiscal Year 2004 (open access)

GAO Performance and Accountability Highlights: Fiscal Year 2004

Other written product issued by the Government Accountability Office with an abstract that begins "This report presents the highlights of GAO's fiscal year 2004 Performance and Accountability report. In short, fiscal year 2004 was an exceptional year for GAO. For example, we received a clean opinion from independent auditors on our financial statements and met or exceeded all but one of our key performance measures. In addition, we exceeded or equaled our all-time record for six of our seven key performance indicators while continuing to improve our client and employee feedback survey results. We documented $44 billion in financial benefits--a return of $95 for every dollar spent, or $13.7 million per employee. We also recorded over 1,000 nonfinancial benefits that helped to shape important legislation and increase the efficiency of various federal programs, thus improving the lives of millions of Americans. In addition, the rate at which our recommendations had been implemented by the Congress or federal agencies rose to 83 percent, and we made over 2,700 new recommendations in fiscal year 2004. We just missed our timeliness goal by delivering 97 percent of our products to the Congress when promised. This summary of our performance and accountability report highlights …
Date: January 1, 2005
Creator: United States. Government Accountability Office.
Object Type: Text
System: The UNT Digital Library
High-Risk Series: An Update (open access)

High-Risk Series: An Update

A letter report issued by the Government Accountability Office with an abstract that begins "GAO's audits and evaluations identify federal programs and operations that, in some cases, are high risk due to their greater vulnerabilities to fraud, waste, abuse, and mismanagement. Increasingly, GAO also is identifying high-risk areas to focus on the need for broad-based transformations to address major economy, efficiency, or effectiveness challenges. Since 1990, GAO has periodically reported on government operations that it has designated as high risk. In this 2005 update for the 109th Congress, GAO presents the status of high-risk areas identified in 2003 and new high-risk areas warranting attention by the Congress and the administration. Lasting solutions to high-risk problems offer the potential to save billions of dollars, dramatically improve service to the American public, strengthen public confidence and trust in the performance and accountability of our national government, and ensure the ability of government to deliver on its promises."
Date: January 1, 2005
Creator: United States. Government Accountability Office.
Object Type: Report
System: The UNT Digital Library
System of systems modeling and analysis. (open access)

System of systems modeling and analysis.

This report documents the results of an LDRD program entitled 'System of Systems Modeling and Analysis' that was conducted during FY 2003 and FY 2004. Systems that themselves consist of multiple systems (referred to here as System of Systems or SoS) introduce a level of complexity to systems performance analysis and optimization that is not readily addressable by existing capabilities. The objective of the 'System of Systems Modeling and Analysis' project was to develop an integrated modeling and simulation environment that addresses the complex SoS modeling and analysis needs. The approach to meeting this objective involved two key efforts. First, a static analysis approach, called state modeling, has been developed that is useful for analyzing the average performance of systems over defined use conditions. The state modeling capability supports analysis and optimization of multiple systems and multiple performance measures or measures of effectiveness. The second effort involves time simulation which represents every system in the simulation using an encapsulated state model (State Model Object or SMO). The time simulation can analyze any number of systems including cross-platform dependencies and a detailed treatment of the logistics required to support the systems in a defined mission.
Date: January 1, 2005
Creator: Campbell, James E.; Anderson, Dennis James; Longsine, Dennis E. & Shirah, Donald N.
Object Type: Report
System: The UNT Digital Library
External Second Gate-Fourier Transform Ion Mobility Spectrometry. (open access)

External Second Gate-Fourier Transform Ion Mobility Spectrometry.

Ion mobility spectrometry (IMS) is recognized as one of the most sensitive and versatile techniques for the detection of trace levels of organic vapors. IMS is widely used for detecting contraband narcotics, explosives, toxic industrial compounds and chemical warfare agents. Increasing threat of terrorist attacks, the proliferation of narcotics, Chemical Weapons Convention treaty verification as well as humanitarian de-mining efforts has mandated that equal importance be placed on the analysis time as well as the quality of the analytical data. (1) IMS is unrivaled when both speed of response and sensitivity has to be considered. (2) With conventional (signal averaging) IMS systems the number of available ions contributing to the measured signal to less than 1%. Furthermore, the signal averaging process incorporates scan-to-scan variations decreasing resolution. With external second gate Fourier Transform ion mobility spectrometry (FT-IMS), the entrance gate frequency is variable and can be altered in conjunction with other data acquisition parameters to increase the spectral resolution. The FT-IMS entrance gate operates with a 50% duty cycle and so affords a 7 to 10-fold increase in sensitivity. Recent data on high explosives are presented to demonstrate the parametric optimization in sensitivity and resolution of our system.
Date: January 1, 2005
Creator: Tarver, Edward E., III
Object Type: Report
System: The UNT Digital Library
Technology Gap Analysis for the Detection of Process Signatures Using Less Than Remote Methods (open access)

Technology Gap Analysis for the Detection of Process Signatures Using Less Than Remote Methods

Although remote sensing methods offer advantages for monitoring important illicit process activities, remote and stand-off technologies cannot successfully detect all important processes with the sensitivity and certainty that is desired. The main scope of the program is observables, with a primary focus on chemical signatures. A number of key process signatures elude remote or stand-off detection for a variety of reasons (e.g., heavy particulate emissions that do not propagate far enough for detection at stand-off distances, semi-volatile chemicals that do not tend to vaporize and remain in the environment near the source, etc.). Some of these compounds can provide persistent, process-specific information that is not available through remote techniques; however, the associated measurement technologies have their own set of advantages, disadvantages and technical challenges that may need to be overcome before additional signature data can be effectively and reliably exploited. The main objective of this report is to describe a process to identify high impact technology gaps for important less-than-remote detection applications. The subsequent analysis focuses on the technology development needed to enable exploitation of important process signatures. The evaluation process that was developed involves three interrelated and often conflicting requirements generation activities: • Identification of target signature chemicals with …
Date: January 1, 2005
Creator: Hartman, John S.; Atkinson, David A.; Lind, Michael A.; Maughan, A. D. & Kelly, James F.
Object Type: Report
System: The UNT Digital Library
Synthesis of a photoresponsive polymer and its incorporation into an organic superlattice. (open access)

Synthesis of a photoresponsive polymer and its incorporation into an organic superlattice.

The synthesis of a photoswitchable polymer by grafting an azobenzene dye to methacrylate followed by polymerization is presented. The azobenzene dye undergoes a trans-cis photoisomerization that causes a persistent change in the refractive index of cast polymer films. This novel polymer was incorporated into superlattices prepared by spin casting and the optical activity of the polymer was maintained. A modified coextruder that allows the rapid production of soft matter superlattices was designed and fabricated.
Date: January 1, 2005
Creator: Morales, Alfredo Martin; Rondeau, Chris J. (Sandia National Laboratories, Albuquerque, NM); McElhanon, James Ross & Cole, Phillip James (Sandia National Laboratories, Albuquerque, NM)
Object Type: Report
System: The UNT Digital Library
LDRD final report on engineered superconductivity in electron-hole bilayers. (open access)

LDRD final report on engineered superconductivity in electron-hole bilayers.

Macroscopic quantum states such as superconductors, Bose-Einstein condensates and superfluids are some of the most unusual states in nature. In this project, we proposed to design a semiconductor system with a 2D layer of electrons separated from a 2D layer of holes by a narrow (but high) barrier. Under certain conditions, the electrons would pair with the nearby holes and form excitons. At low temperature, these excitons could condense to a macroscopic quantum state either through a Bose-Einstein condensation (for weak exciton interactions) or a BCS transition to a superconductor (for strong exciton interactions). While the theoretical predictions have been around since the 1960's, experimental realization of electron-hole bilayer systems has been extremely difficult due to technical challenges. We identified four characteristics that if successfully incorporated into a device would give the best chances for excitonic condensation to be observed. These characteristics are closely spaced layers, low disorder, low density, and independent contacts to allow transport measurements. We demonstrated each of these characteristics separately, and then incorporated all of them into a single electron-hole bilayer device. The key to the sample design is using undoped GaAs/AlGaAs heterostructures processed in a field-effect transistor geometry. In such samples, the density of single …
Date: January 1, 2005
Creator: Lyo, Sungkwun Kenneth; Dunn, Roberto G.; Lilly, Michael Patrick; Tibbetts-Russell, D. R.; Stephenson, Larry L.; Seamons, John Andrew et al.
Object Type: Report
System: The UNT Digital Library
Model-building codes for membrane proteins. (open access)

Model-building codes for membrane proteins.

We have developed a novel approach to modeling the transmembrane spanning helical bundles of integral membrane proteins using only a sparse set of distance constraints, such as those derived from MS3-D, dipolar-EPR and FRET experiments. Algorithms have been written for searching the conformational space of membrane protein folds matching the set of distance constraints, which provides initial structures for local conformational searches. Local conformation search is achieved by optimizing these candidates against a custom penalty function that incorporates both measures derived from statistical analysis of solved membrane protein structures and distance constraints obtained from experiments. This results in refined helical bundles to which the interhelical loops and amino acid side-chains are added. Using a set of only 27 distance constraints extracted from the literature, our methods successfully recover the structure of dark-adapted rhodopsin to within 3.2 {angstrom} of the crystal structure.
Date: January 1, 2005
Creator: Shirley, David Noyes; Hunt, Thomas W.; Brown, W. Michael; Schoeniger, Joseph S. (Sandia National Laboratories, Livermore, CA); Slepoy, Alexander; Sale, Kenneth L. (Sandia National Laboratories, Livermore, CA) et al.
Object Type: Report
System: The UNT Digital Library
Near net shape forming processes for chemically prepared zinc oxide varistors. (open access)

Near net shape forming processes for chemically prepared zinc oxide varistors.

Chemically prepared zinc oxide powders are fabricated for the production of high aspect ratio varistor components. Colloidal processing in water was performed to reduce agglomerates to primary particles, form a high solids loading slurry, and prevent dopant migration. The milled and dispersed powder exhibited a viscoelastic to elastic behavioral transition at a volume loading of 43-46%. The origin of this transition was studied using acoustic spectroscopy, zeta potential measurements and oscillatory rheology. The phenomenon occurs due to a volume fraction solids dependent reduction in the zeta potential of the solid phase. It is postulated to result from divalent ion binding within the polyelectrolyte dispersant chain, and was mitigated using a polyethylene glycol plasticizing additive. Chemically prepared zinc oxide powders were processed for the production of high aspect ratio varistor components. Near net shape casting methods including slip casting and agarose gelcasting were evaluated for effectiveness in achieving a uniform green microstructure achieving density values near the theoretical maximum during sintering. The structure of the green parts was examined by mercury porisimetry. Agarose gelcasting produced green parts with low solids loading values and did not achieve high fired density. Isopressing the agarose cast parts after drying raised the fired density to …
Date: January 1, 2005
Creator: Lockwood, Steven John; Voigt, James A.; Tuttle, Bruce Andrew & Bell, Nelson Simmons
Object Type: Report
System: The UNT Digital Library
A Search for Long-Lived Doubly-Charged Higgs Boson Production in anti-p p Collisions at sqrt(s)=1.96 TeV using RunII CDF (open access)

A Search for Long-Lived Doubly-Charged Higgs Boson Production in anti-p p Collisions at sqrt(s)=1.96 TeV using RunII CDF

We present a search for a quasi-stable doubly-charged Higgs particle at CDF using the Fermilab Tevatron for {radical}s = 1.96 TeV. The data presented are from approximately 290 pb{sup -1} of integrated luminosity collected using the upgraded Run 2 Collider Detector at Fermilab. These data were taken between February, 2002 and February, 2004. The long-lived decay products of Z's are selected in the central detector region (|{eta}| < 1.0). They select events triggered on a muon candidate having p{sub T} > 18 GeV in the event. After offline reconstruction, they require two isolated tracks (p{sub T} > 20 GeV) in the event, one of which points to a stub in a muon detector. Since the search is based on the increased ionization a doubly-charged particle would produce as it passes through the detector, they require that both tracks be highly ionizing for an event to be selected as a H{sup {+-}{+-}} candidate. No such candidates are observed in the data. They set a lower mass limit of 146 GeV on a quasi-stable H{sup {+-}{+-}} boson.
Date: January 1, 2005
Creator: Tuttle, Joshua P. & U., /Duke
Object Type: Report
System: The UNT Digital Library
Performance of Ultra-Scale Applications on Leading Vector andScalar HPC Platforms (open access)

Performance of Ultra-Scale Applications on Leading Vector andScalar HPC Platforms

The last decade has witnessed a rapid proliferation of superscalar cache-based microprocessors to build high-end capability and capacity computers primarily because of their generality, scalability, and cost effectiveness. However, the constant degradation of superscalar sustained performance, has become a well-known problem in the scientific computing community. This trend has been widely attributed to the use of superscalar-based commodity components who's architectural designs offer a balance between memory performance, network capability, and execution rate that is poorly matched to the requirements of large-scale numerical computations. The recent development of massively parallel vector systems offers the potential to increase the performance gap for many important classes of algorithms. In this study we examine four diverse scientific applications with the potential to run at ultrascale, from the areas of plasma physics, material science, astrophysics, and magnetic fusion. We compare performance between the vector-based Earth Simulator (ES) and Cray X1, with leading superscalar-based platforms: the IBM Power3/4 and the SGI Altix. Results demonstrate that the ES vector systems achieve excellent performance on our application suite - the highest of any architecture tested to date.
Date: January 1, 2005
Creator: Oliker, Leonid; Canning, Andrew; Carter, Jonathan Carter; Shalf,John; Simon, Horst; Ethier, Stephane et al.
Object Type: Article
System: The UNT Digital Library
Graduated embodiment for sophisticated agent evolution and optimization. (open access)

Graduated embodiment for sophisticated agent evolution and optimization.

We summarize the results of a project to develop evolutionary computing methods for the design of behaviors of embodied agents in the form of autonomous vehicles. We conceived and implemented a strategy called graduated embodiment. This method allows high-level behavior algorithms to be developed using genetic programming methods in a low-fidelity, disembodied modeling environment for migration to high-fidelity, complex embodied applications. This project applies our methods to the problem domain of robot navigation using adaptive waypoints, which allow navigation behaviors to be ported among autonomous mobile robots with different degrees of embodiment, using incremental adaptation and staged optimization. Our approach to biomimetic behavior engineering is a hybrid of human design and artificial evolution, with the application of evolutionary computing in stages to preserve building blocks and limit search space. The methods and tools developed for this project are directly applicable to other agent-based modeling needs, including climate-related conflict analysis, multiplayer training methods, and market-based hypothesis evaluation.
Date: January 1, 2005
Creator: Pierson, Arthurine Renee; Peters, Michael D. & Boslough, Mark Bruce Elrick
Object Type: Report
System: The UNT Digital Library
Simplifying the assessment of building vulnerability to chemical,biological and radiological releases (open access)

Simplifying the assessment of building vulnerability to chemical,biological and radiological releases

The intentional or accidental release of airborne chemical, biological, or radiological materials can pose a significant threat to the health of building occupants. Pre-planning and emergency response measures, such as HVAC system manipulation and sheltering during an event, can significantly reduce the exposure of building occupants. A straightforward and comprehensive vulnerability assessment methodology is an essential tool for assisting building managers and operators in preparing for airborne hazards.
Date: January 1, 2005
Creator: Thatcher, T. L.; Wood, E. E.; Edelson, E. C. & Sextro, R. G.
Object Type: Report
System: The UNT Digital Library
MiniSAR composite gimbal arm development. (open access)

MiniSAR composite gimbal arm development.

An exploratory effort in the application of carbon epoxy composite structural materials to a multi-axis gimbal arm design is described. An existing design in aluminum was used as a baseline for a functionally equivalent redesigned outer gimbal arm using a carbon epoxy composite material. The existing arm was analyzed using finite element techniques to characterize performance in terms of strength, stiffness, and weight. A new design was virtually prototyped. using the same tools to produce a design with similar stiffness and strength, but reduced overall weight, than the original arm. The new design was prototyped using Rapid Prototyping technology, which was subsequently used to produce molds for fabricating the carbon epoxy composite parts. The design tools, process, and results are discussed.
Date: January 1, 2005
Creator: Klarer, Paul Richard & Winscott, Mark (Orion International, Albuquerque, NM)
Object Type: Report
System: The UNT Digital Library
Characterizing the effects of scale and heating rate on micro-scale explosive ignition criteria. (open access)

Characterizing the effects of scale and heating rate on micro-scale explosive ignition criteria.

Laser diode ignition experiments were conducted in an effort to characterize the effects of scale and heating rate on micro-scale explosive ignition criteria. Over forty experiments were conducted with various laser power densities and laser spot sizes. In addition, relatively simple analytical and numerical calculations were performed to assist with interpretation of the experimental data and characterization of the explosive ignition criteria.
Date: January 1, 2005
Creator: Hafenrichter, Everett Shingo & Pahl, Robert J.
Object Type: Report
System: The UNT Digital Library
Measurement and modeling of energetic material mass transfer to soil pore water : Project CP-1227 : FY04 annual technical report. (open access)

Measurement and modeling of energetic material mass transfer to soil pore water : Project CP-1227 : FY04 annual technical report.

Military test and training ranges operate with live fire engagements to provide realism important to the maintenance of key tactical skills. Ordnance detonations during these operations typically produce minute residues of parent explosive chemical compounds. Occasional low order detonations also disperse solid phase energetic material onto the surface soil. These detonation remnants are implicated in chemical contamination impacts to groundwater on a limited set of ranges where environmental characterization projects have occurred. Key questions arise regarding how these residues and the environmental conditions (e.g., weather and geostratigraphy) contribute to groundwater pollution impacts. This report documents interim results of a mass transfer model evaluating mass transfer processes from solid phase energetics to soil pore water based on experimental work obtained earlier in this project. This mass transfer numerical model has been incorporated into the porous media simulation code T2TNT. Next year, the energetic material mass transfer model will be developed further using additional experimental data.
Date: January 1, 2005
Creator: Stein, Joshua S. & Webb, Stephen Walter
Object Type: Report
System: The UNT Digital Library
Biomolecular decision-making process for self assembly. (open access)

Biomolecular decision-making process for self assembly.

The brain is often identified with decision-making processes in the biological world. In fact, single cells, single macromolecules (proteins) and populations of molecules also make simple decisions. These decision processes are essential to survival and to the biological self-assembly and self-repair processes that we seek to emulate. How do these tiny systems make effective decisions? How do they make decisions in concert with a cooperative network of other molecules or cells? How can we emulate the decision-making behaviors of small-scale biological systems to program and self-assemble microsystems? This LDRD supported research to answer these questions. Our work included modeling and simulation of protein populations to help us understand, mimic, and categorize molecular decision-making mechanisms that nonequilibrium systems can exhibit. This work is an early step towards mimicking such nanoscale and microscale biomolecular decision-making processes in inorganic systems.
Date: January 1, 2005
Creator: Osbourn, Gordon Cecil
Object Type: Report
System: The UNT Digital Library
In-vessel Retention Strategy for High Power Reactors - K-INERI Final Report (includes SBLB Test Results for Task 3 on External Reactor Vessel Cooling (ERVC) Boiling Data and CHF Enhancement Correlations) (open access)

In-vessel Retention Strategy for High Power Reactors - K-INERI Final Report (includes SBLB Test Results for Task 3 on External Reactor Vessel Cooling (ERVC) Boiling Data and CHF Enhancement Correlations)

In-vessel retention (IVR) of core melt is a key severe accident management strategy adopted by some operating nuclear power plants and proposed for some advanced light water reactors (ALWRs). If there were inadequate cooling during a reactor accident, a significant amount of core material could become molten and relocate to the lower head of the reactor vessel, as happened in the Three Mile Island Unit 2 (TMI-2) accident. If it is possible to ensure that the vessel head remains intact so that relocated core materials are retained within the vessel, the enhanced safety associated with these plants can reduce concerns about containment failure and associated risk. For example, the enhanced safety of the Westinghouse Advanced 600 MWe PWR (AP600), which relied upon External Reactor Vessel Cooling (ERVC) for IVR, resulted in the U.S. Nuclear Regulatory Commission (US NRC) approving the design without requiring certain conventional features common to existing LWRs. However, it is not clear that currently proposed external reactor vessel cooling (ERVC) without additional enhancements could provide sufficient heat removal for higher-power reactors (up to 1500 MWe). Hence, a collaborative, three-year, U.S. - Korean International Nuclear Energy Research Initiative (INERI) project was completed in which the Idaho National Engineering …
Date: January 1, 2005
Creator: Cheung, F. B.; Yang, J.; Dizon, M. B. & Rempe, J.
Object Type: Report
System: The UNT Digital Library
Genomes to life project quarterly report June 2004. (open access)

Genomes to life project quarterly report June 2004.

This SAND report provides the technical progress through June 2004 of the Sandia-led project, ''Carbon Sequestration in Synechococcus Sp.: From Molecular Machines to Hierarchical Modeling'', funded by the DOE Office of Science Genomes to Life Program. Understanding, predicting, and perhaps manipulating carbon fixation in the oceans has long been a major focus of biological oceanography and has more recently been of interest to a broader audience of scientists and policy makers. It is clear that the oceanic sinks and sources of CO{sub 2} are important terms in the global environmental response to anthropogenic atmospheric inputs of CO{sub 2} and that oceanic microorganisms play a key role in this response. However, the relationship between this global phenomenon and the biochemical mechanisms of carbon fixation in these microorganisms is poorly understood. In this project, we will investigate the carbon sequestration behavior of Synechococcus Sp., an abundant marine cyanobacteria known to be important to environmental responses to carbon dioxide levels, through experimental and computational methods. This project is a combined experimental and computational effort with emphasis on developing and applying new computational tools and methods. Our experimental effort will provide the biology and data to drive the computational efforts and include significant investment …
Date: January 1, 2005
Creator: Heffelfinger, Grant S.
Object Type: Report
System: The UNT Digital Library
Nanomaterials for directed energy transfer. (open access)

Nanomaterials for directed energy transfer.

None
Date: January 1, 2005
Creator: Sinclair, Michael B.; Last, Julie A.; Slade, Andrea Lynn; Westrich, Thomas A.; Sasaki, Darryl Yoshio; Floro, Jerrold Anthony et al.
Object Type: Report
System: The UNT Digital Library
Suitability of Magnesium Oxide as a Visar Window (open access)

Suitability of Magnesium Oxide as a Visar Window

Impedance matching of a velocity interferometer for any reflector (VISAR) window to a material under study helps simplify a shock experiment by effectively allowing one to measure an in situ particle velocity. The shock impedance of magnesium oxide (MgO) falls roughly midway between those of sapphire and LiF, two of the most frequently used VISAR window materials. A series of symmetric impact experiments was performed to characterize the suitability of single crystal, (100) oriented magnesium oxide as a VISAR window material. These experiments yielded good results and show the viability of MgO as a VISAR window up to 23 GPa. Results were used to determine window correction factors and, subsequently, to estimate the pressure induced change in index of refraction. In many of the shots in this work we exceeded the Hugoniot elastic limit (HEL) of MgO, and both elastic and plastic waves are evident in the velocity profiles. The presence of both waves within the VISAR window complicates the typical VISAR window correction analysis. Preliminary analysis of the elastic and plastic contributions to the window correction is presented.
Date: January 1, 2005
Creator: Stevens, G. D.; Veeser, L. R.; Rigg, P. A. & Hixson, R. S.
Object Type: Article
System: The UNT Digital Library
Advanced polychromator systems for remote chemical sensing (LDRD project 52575). (open access)

Advanced polychromator systems for remote chemical sensing (LDRD project 52575).

The objective of this LDRD project was to develop a programmable diffraction grating fabricated in SUMMiT V{trademark}. Two types of grating elements (vertical and rotational) were designed and demonstrated. The vertical grating element utilized compound leveraged bending and the rotational grating element used vertical comb drive actuation. This work resulted in two technical advances and one patent application. Also a new optical configuration of the Polychromator was demonstrated. The new optical configuration improved the optical efficiency of the system without degrading any other aspect of the system. The new configuration also relaxes some constraint on the programmable diffraction grating.
Date: January 1, 2005
Creator: Sinclair, Michael B.; Pfeifer, Kent Bryant & Allen, James Joe
Object Type: Report
System: The UNT Digital Library
Saturation of CVD Diamond Detectors (open access)

Saturation of CVD Diamond Detectors

A 5 x 0.25 mm Chemical Vapor Deposited (CVD) diamond detector, with a voltage bias of + 250V, was excited by a 400 nm laser (3.1 eV photons) in order to study the saturation of the wafer and its surrounding electronics. In a first experiment, the laser beam energy was increased from a few tens of a pJ to about 100 µJ, and the signal from the diamond was recorded until full saturation of the detection system was achieved. Clear saturation of the detection system was observed at about 40 V, which corresponds with the expected saturation at 10% of the applied bias (250V). The results indicate that the interaction mechanism of the 3.1 eV photons in the diamond (Ebandgap = 5.45 eV) is not a multi-photon process but is linked to the impurities and defects of the crystal. In a second experiment, the detector was irradiated by a saturating first laser pulse and then by a delayed laser pulse of equal or smaller amplitude with delays of 5, 10, and 20 ns. The results suggest that the diamond and associated electronics recover within 10 to 20 ns after a strong saturating pulse.
Date: January 1, 2005
Creator: Dauffy, Lucile S.; Lerche, Richard A.; Schmid, Greg J.; Koch, Jeffrey A. & Silbernagel, Christopher
Object Type: Article
System: The UNT Digital Library
Quantum squeezed light for probing mitochondrial membranes and study of neuroprotectants. (open access)

Quantum squeezed light for probing mitochondrial membranes and study of neuroprotectants.

We report a new nanolaser technique for measuring characteristics of human mitochondria. Because mitochondria are so small, it has been difficult to study large populations using standard light microscope or flow cytometry techniques. We recently discovered a nano-optical transduction method for high-speed analysis of submicron organelles that is well suited to mitochondrial studies. This ultrasensitive detection technique uses nano-squeezing of light into photon modes imposed by the ultrasmall organelle dimensions in a semiconductor biocavity laser. In this paper, we use the method to study the lasing spectra of normal and diseased mitochondria. We find that the diseased mitochondria exhibit larger physical diameter and standard deviation. This morphological differences are also revealed in the lasing spectra. The diseased specimens have a larger spectral linewidth than the normal, and have more variability in their statistical distributions.
Date: January 1, 2005
Creator: Gourley, Paul Lee; Copeland, Robert Guild; McDonald, Anthony Eugene; Hendricks, Judy K. & Naviaux, Robert K. (University of California, San Diego, CA)
Object Type: Report
System: The UNT Digital Library