34 Matching Results

Search Results

The Effect of Government Actions on Environmental Technology Innovation: Applications to the Integrated Assessment of Carbon Sequestration Technologies

Description: This project seeks to improve the ability of integrated assessment models (IA) to incorporate changes in technology, especially environmental technologies, cost and performance over time. In this report, we present results of research that examines past experience in controlling other major power plant emissions that might serve as a reasonable guide to future rates of technological progress in carbon capture and sequestration (CCS) systems. In particular, we focus on U.S. and worldwide experience with sulfur dioxide (SO{sub 2}) and nitrogen oxide (NO{sub x}) control technologies over the past 30 years, and derive empirical learning rates for these technologies. The patterns of technology innovation are captured by our analysis of patent activities and trends of cost reduction over time. Overall, we found learning rates of 11% for the capital costs of flue gas desulfurization (FGD) system for SO{sub 2} control, and 13% for selective catalytic reduction (SCR) systems for NO{sub x} control. We explore the key factors responsible for the observed trends, especially the development of regulatory policies for SO{sub 2} and NO{sub x} control, and their implications for environmental control technology innovation.
Date: January 15, 2004
Creator: Rubin, E. S.; Hounshell, D. A.; Yeh, S.; Taylor, M.; Schrattenholzer, L.; Riahi, K. et al.
Partner: UNT Libraries Government Documents Department

Robust Background Subtraction with Foreground Validation for Urban Traffic Video

Description: Identifying moving objects in a video sequence is a fundamental and critical task in many computer-vision applications. Background subtraction techniques are commonly used to separate foreground moving objects from the background. Most background subtraction techniques assume a single rate of adaptation, which is inadequate for complex scenes such as a traffic intersection where objects are moving at different and varying speeds. In this paper, we propose a foreground validation algorithm that first builds a foreground mask using a slow-adapting Kalman filter, and then validates individual foreground pixels by a simple moving object model, built using both the foreground and background statistics as well as the frame difference. Ground-truth experiments with urban traffic sequences show that our proposed algorithm significantly improves upon results using only Kalman filter or frame-differencing, and outperforms other techniques based on mixture of Gaussians, median filter, and approximated media filter.
Date: January 15, 2004
Creator: Cheung, S. S. & Kamath, C
Partner: UNT Libraries Government Documents Department

Effect of GaN template layer strain on the growth of InxGa1-xN/GaN MQW light emitting diodes

Description: GaN template layer strain effects were investigated on the growth of InGaN/GaN LED devices. Seven period InGaN/GaN multiple quantum well structures were deposited on 5{micro}m and 15{micro}m GaN template layers. It was found that the electroluminescence emission of the 15{micro}m device was red-shifted by approximately 132meV. Triple-axis X-Ray Diffraction and Cross-Sectional Transmission Electron Microscopy show that the 15{micro}m templay layer device was virtually unstrained while the 5{micro}m layer experienced tensile strain. Dynamic Secondary Ion Mass Spectrometry depth profiles show that the 15{micro}m template layer device had an average indium concentration of 11% higher than that of the 5{micro}m template layer device even though the structures were deposited during the same growth run. It was also found that the 15{micro}m layer device had a higher growth rate than the 5{micro}m template layer device. This difference in indium concentration and growth rate was due to changes in thermodynamic limitations caused by strain differences in the template layers.
Date: January 15, 2004
Creator: Johnson, M.C.; Bourret-Courchesne, E.D.; Wu, J.; Liliental-Weber, Z.; Zakharov, D.N.; Jorgenson, R.J. et al.
Partner: UNT Libraries Government Documents Department

Mechanism of lipid lowering in mice expressing human apolipoprotein A5

Description: Recently, we reported that apoAV plays key role in triglycerides lowering. Here, we attempted to determine the mechanism underlying this hypotriglyceridemic effect. We showed that triglyceride turnover is faster in hAPOA5 transgenic compared to wild type mice. Moreover, both apoB and apoCIII are decreased and LPL activity is increased in postheparin plasma of hAPOA5 transgenic mice. These data suggest a decrease in size and number of VLDL. To further investigate the mechanism of hAPOA5 in hyperlipidemic background, we intercrossed hAPOA5 and hAPOC3 transgenic mice. The effect resulted in a marked decreased of VLDL triglyceride, cholesterol, apolipoproteins B and CIII. In postprandial state, the triglyceride response is abolished in hAPOA5 transgenic mice. We demonstrated that in response to the fat load in hAPOA5XhAPOC3 mice, apoAV shifted from HDL to VLDL, probably to limit the elevation of triglycerides. In vitro, apoAV activates lipoprotein lipase. However, apoAV does not interact with LPL but interacts physically with apoCIII. This interaction does not seem to displace apoCIII from VLDL but may induce conformational change in apoCIII and consequently change in its function leading the activation of lipoprotein lipase.
Date: January 15, 2004
Creator: Fruchart-Najib, Jamila; Bauge, Eric; Niculescu, Loredan-Stefan; Pham, Tatiana; Thomas, Benoit; Rommens, Corinne et al.
Partner: UNT Libraries Government Documents Department

Cathepsin L is required for endothelial progenitor cell-induced neovascularization

Description: Infusion of endothelial progenitor cells (EPCs), but not of mature endothelial cells (ECs), promotes neovascularization after ischemia. We performed a gene expression profiling of EPCs and ECs to identify genes, which might be important for the neovascularization capacity of EPCs. Intriguingly, the protease cathepsin L (CathL) was highly expressed in EPCs as opposed to ECs and is essential for matrix degradation and invasion by EPCs in vitro. CathL deficient mice showed impaired functional recovery after hind limb ischemia supporting the concept for an important role of CathL in postnatal neovascularization. Infused CathL deficient progenitor cells failed to home to sites of ischemia and to augment neovascularization. In contrast, over expression of CathL in mature ECs significantly enhanced their invasive activity and induced their neovascularization capacity in vivo. Taken together, CathL plays a crucial role for the integration of circulating EPCs into the ischemic tissue and is required for neovascularization mediated by EPCs.
Date: January 15, 2004
Creator: Urbich, Carmen; Heeschen, Christopher; Aicher, Alexandra; Sasaki, Ken-ichiro; Bruhl, Thomas; Hofmann, Wolf K. et al.
Partner: UNT Libraries Government Documents Department

eShadow: A tool for comparing closely related sequences

Description: Primate sequence comparisons are difficult to interpret due to the high degree of sequence similarity shared between such closely related species. Recently, a novel method, phylogenetic shadowing, has been pioneered for predicting functional elements in the human genome through the analysis of multiple primate sequence alignments. We have expanded this theoretical approach to create a computational tool, eShadow, for the identification of elements under selective pressure in multiple sequence alignments of closely related genomes, such as in comparisons of human to primate or mouse to rat DNA. This tool integrates two different statistical methods and allows for the dynamic visualization of the resulting conservation profile. eShadow also includes a versatile optimization module capable of training the underlying Hidden Markov Model to differentially predict functional sequences. This module grants the tool high flexibility in the analysis of multiple sequence alignments and in comparing sequences with different divergence rates. Here, we describe the eShadow comparative tool and its potential uses for analyzing both multiple nucleotide and protein alignments to predict putative functional elements. The eShadow tool is publicly available at http://eshadow.dcode.org/
Date: January 15, 2004
Creator: Ovcharenko, Ivan; Boffelli, Dario & Loots, Gabriela G.
Partner: UNT Libraries Government Documents Department

Sum frequency generation (SFQ) vibrational spectroscopy studies of combustion reactions on platinum single crystal surfaces

Description: We have studied the dissociation of CO catalyzed by platinum single crystals. At 40 torr of CO, the Pt(111) crystal dissociates CO at 673 K. Under the same conditions, Pt(100) dissociates CO at 500 K, and Pt(557) dissociates CO at 548 K. Hence, the CO dissociation reaction is a structure sensitive reaction. SFG was used to monitor the CO top site resonance as the platinum crystals were heated to the dissociation temperature when exposed to 40 torr of CO. In all three systems, the CO resonance shifts to lower frequency as the platinum crystal is heated. However, the frequency of the CO resonance at the dissociation frequency is lower on the (100) and (111) crystal faces than on the Pt(557) crystal. We believe that the (111) and (100) crystal faces must undergo roughening to expose step or kink sites in order to facilitate the dissociation reaction. This is supported by UHV studies of CO dissociation catalyzed by platinum crystals. These studies observe dissociation only when step or kink sites are present. Since the Pt(111) surface is very stable, it needs to be heated to 673 K to produce the low coordination number sites needed for CO dissociation. Since the Pt(100) surface easily reconstructs, it is able to form the active sites for CO dissociation at relatively low temperatures. The SFG spectra support our conclusion that the CO molecules are sitting on low coordination number platinum atoms at the dissociation temperature. Since the Pt(557) surface already has step sites, the dissociation reaction can take place without further roughening of the surface. The CO resonance on the (557) crystal face at the dissociation temperature is at a very similar frequency to CO molecules adsorbed on only the step sites of the crystal. Further studies showed that the dissociation reaction takes place on ...
Date: January 15, 2004
Creator: Gaughan, Jessica S.
Partner: UNT Libraries Government Documents Department

Noise minimization in eukaryotic gene expression

Description: All organisms have elaborate mechanisms to control rates of protein production. However, protein production is also subject to stochastic fluctuations, or noise. Several recent studies in Saccharomyces cerevisiae and Escherichia coli have investigated the relationship between transcription and translation rates and stochastic fluctuations in protein levels, or more generally, how such randomness is a function of intrinsic and extrinsic factors. However, the fundamental question of whether stochasticity in protein expression is generally biologically relevant has not been addressed, and it remains unknown whether random noise in the protein production rate of most genes significantly affects the fitness of any organism. We propose that organisms should be particularly sensitive to variation in the protein levels of two classes of genes: genes whose deletion is lethal to the organism and genes that encode subunits of multiprotein complexes. Using an experimentally verified model of stochastic gene expression in S. cerevisiae, we estimate the noise in protein production for nearly every yeast gene, and confirm our prediction that the production of essential and complex-forming proteins involves lower levels of noise than does the production of most other genes. Our results support the hypothesis that noise in gene expression is a biologically important variable, is generally detrimental to organismal fitness, and is subject to natural selection.
Date: January 15, 2004
Creator: Fraser, Hunter B.; Hirsh, Aaron E.; Giaever, Guri; Kumm, Jochen & Eisen, Michael B.
Partner: UNT Libraries Government Documents Department

Space Shuttle: Further Improvements Needed in NASA's Modernization Efforts

Description: A letter report issued by the General Accounting Office with an abstract that begins "The Columbia tragedy has accentuated the need to modernize the 20-year-old space shuttle, the only U.S. launch system that carries people to and from space. The shuttle will now be needed for another two decades. As it ages, the spacecraft's components will also age, and it may become increasingly unreliable. GAO examined the National Aeronautics and Space Administration's (NASA) plans to upgrade the shuttle through 2020, how it will identify and select what upgrades are needed, how much the upgrades may cost, and what factors will influence that cost over the system's lifetime."
Date: January 15, 2004
Creator: United States. General Accounting Office.
Partner: UNT Libraries Government Documents Department

Regulating Private Pensions: A Brief Summary of ERISA

Description: This report briefly discusses the Employee Retirement Income Security Act of 1974 (ERISA), and how it protects the interests of participants and beneficiaries in private-sector employee benefit plans. ERISA covers a number of fringe benefits provided by employers, but most of its provisions deal with pension plans. Pension plans sponsored by the federal, state, and local governments, or by churches generally are exempt from ERISA.
Date: January 15, 2004
Creator: Purcell, Patrick
Partner: UNT Libraries Government Documents Department

2010 Census: Cost and Design Issues Need to Be Addressed Soon

Description: A letter report issued by the General Accounting Office with an abstract that begins "The key to a successful census is meticulous planning as it helps ensure greater cost-effectiveness. However, the 2000 and previous censuses have been marked by poor planning, which unnecessarily raised the costs and risks of those efforts. GAO was asked to (1) review the U.S. Census Bureau's (Bureau) current plans for 2010 and whether they might address shortcomings of the 2000 Census, (2) analyze the Bureau's cost estimates, and (3) review the rigor of the Bureau's 2010 planning process."
Date: January 15, 2004
Creator: United States. General Accounting Office.
Partner: UNT Libraries Government Documents Department

World Trade Organization: Cancun Ministerial Fails to Move Global Trade Negotiations Forward; Next Steps Uncertain

Description: A letter report issued by the General Accounting Office with an abstract that begins "Trade ministers from 146 members of the World Trade Organization (WTO), representing 93 percent of global commerce, convened in Cancun, Mexico, in September 2003. Their goal was to provide direction for ongoing trade negotiations involving a broad set of issues that included agriculture, nonagricultural market access, services, and special treatment for developing countries. These negotiations, part of the global round of trade liberalizing talks launched in November 2001 at Doha, Qatar, are an important means of providing impetus to the world's economy. The round was supposed to be completed by January 1, 2005. However, the Cancun Ministerial Conference ultimately collapsed without ministers reaching agreement on any of the key issues. GAO was asked to analyze (1) the divisions on key issues for the Cancun Ministerial Conference and how they were dealt with at Cancun and (2) the factors that influenced the outcome of the Cancun Ministerial Conference."
Date: January 15, 2004
Creator: United States. General Accounting Office.
Partner: UNT Libraries Government Documents Department

Optimal Resource Allocation in Electrical Network Defense

Description: Infrastructure networks supplying electricity, natural gas, water, and other commodities are at risk of disruption due to well-engineered and coordinated terrorist attacks. Countermeasures such as hardening targets, acquisition of spare critical components, and surveillance can be undertaken to detect and deter these attacks. Allocation of available countermeasures resources to sites or activities in a manner that maximizes their effectiveness is a challenging problem. This allocation must take into account the adversary's response after the countermeasure assets are in place and consequence mitigation measures the infrastructure operation can undertake after the attack. The adversary may simply switch strategies to avoid countermeasures when executing the attack. Stockpiling spares of critical energy infrastructure components has been identified as a key element of a grid infrastructure defense strategy in a recent National Academy of Sciences report [1]. Consider a scenario where an attacker attempts to interrupt the service of an electrical network by disabling some of its facilities while a defender wants to prevent or minimize the effectiveness of any attack. The interaction between the attacker and the defender can be described in three stages: (1) The defender deploys countermeasures, (2) The attacker disrupts the network, and (3) The defender responds to the attack by rerouting power to maintain service while trying to repair damage. In the first stage, the defender considers all possible attack scenarios and deploys countermeasures to defend against the worst scenarios. Countermeasures can include hardening targets, acquiring spare critical components, and installing surveillance devices. In the second stage, the attacker, with full knowledge of the deployed countermeasures, attempts to disable some nodes or links in the network to inflict the greatest loss on the defender. In the third stage, the defender re-dispatches power and restores disabled nodes or links to minimize the loss. The loss can be measured in costs, ...
Date: January 15, 2004
Creator: Yao, Y; Edmunds, T; Papageorgiou, D & Alvarez, R
Partner: UNT Libraries Government Documents Department

Structure, Vibrational and Electronic Spectra of Heterofullerene C48(BN)6

Description: We report the geometrical structure, vibrational, and excitation spectra of novel, fullerene - analog C{sub 48}(BN){sub 6} using density functional calculations. The lowest energy structure is one in which B-N bonding is present as boron and nitrogen occupy each of the twelve pentagons of the fullerene cage. The cluster is polar with a net dipole moment of 0.55 Debye, which indicates an enhanced tendency toward reactivity with other media. The excitation spectrum shows that the lowest transition of 1.75 eV is dipole-allowed. The optical gap of C{sub 48}(BN){sub 6} is redshifted by 1.17 eV relative to that of C{sub 60}, suggesting possible use as single-molecule fluorescent probes for various applications.
Date: January 15, 2004
Creator: Manaa, M R; Xie, R & Smith, Jr., V H
Partner: UNT Libraries Government Documents Department

Child Support Enforcement: New Reforms and Potential Issues

Description: P.L. 104-193 (the 1996 welfare reform legislation) made major changes to the Child Support Enforcement (CSE) program. Some of the changes include requiring states to increase the percentage of fathers identified, establishing an integrated, automated network linking all states to information about the location and assets of parents, and requiring states to implement more enforcement techniques to obtain collections from debtor parents. Additional legislative changes were made in 1997, 1998, and 1999, but not in 2000, 2001, 2002, or 2003. This report describes several aspects of the revised CSE program and discusses three issues that probably will be reexamined by the 108th Congress — CSE financing, parental access by noncustodial parents, and distribution of support payments.
Date: January 15, 2004
Creator: Solomon-Fears, Carmen
Partner: UNT Libraries Government Documents Department

Threatened and Endangered Species Evaluation for Operating Commercial Nuclear Power Generating Plants

Description: The Endangered Species Act (ESA) of 1973 requires that federal agencies ensure that any action authorized, funded, or carried out under their jurisdiction is not likely to jeopardize the continued existence of any threatened or endangered (T&E) species or result in the destruction or adverse modification of critical habitats for such species. The issuance and maintenance of a federal license, such as a construction permit or operating license issued by the U.S. Nuclear Regulatory Commission (NRC) for a commercial nuclear power generating facility is a federal action under the jurisdiction of a federal agency, and is therefore subject to the provisions of the ESA. The Office of Nuclear Reactor Regulation (NRR) staff have performed appropriate assessments of potential impacts to threatened or endangered species, and consulted with appropriate agencies with regard to protection of such species in authorizing the construction, operation, and relicensing of nuclear power generating facilities. However, the assessments and consultations concerning many facilities were performed during the 1970's or early 1980's, and have not been re-evaluated in detail or updated since those initial evaluations. A review of potential Endangered Species Act issues at licensed nuclear power facilities was completed in 1997. In that review 484 different ESA-listed species were identified as potentially occurring near one or more of the 75 facility sites that were examined. An update of the previous T&E species evaluation at this time is desired because, during the intervening 6 years: nearly 200 species have been added to the ESA list, critical habitats have been designated for many of the listed species, and significantly more information is available online, allowing for more efficient high-level evaluations of potential species presence near sites and the potential operation impacts. The updated evaluation included searching the NRC's ADAMS database to find any documents related to T&E species take, ...
Date: January 15, 2004
Creator: Sackschewsky, Michael R.
Partner: UNT Libraries Government Documents Department

INTERNATIONAL CONFERENCE ON ULTRASHORT HIGH-ENERGY RADIATION AND MATTER

Description: The workshop is intended as a forum to discuss the latest experimental, theoretical and computational results related to the interaction of high energy radiation with matter. High energy is intended to mean soft x-ray and beyond, but important new results from visible systems will be incorporated. The workshop will be interdisciplinary amongst scientists from many fields, including: plasma physics; x-ray physics and optics; solid state physics and material science; biology ; quantum optics. Topics will include, among other subjects: understanding damage thresholds for x-ray interactions with matter developing {approx} 5 keV x-ray sources to investigate damage; developing {approx} 100 keV Thomsom sources for material studies; developing short pulse (100 fs and less) x-ray diagnostics; developing novel X-ray optics; and developing models for the response of biological samples to ultra intense, sub ps x-rays high-energy radiation.
Date: January 15, 2004
Creator: Wootton, A J
Partner: UNT Libraries Government Documents Department