Sub-barrier fusion and transfers in the 40Ca + 58,64Ni systems

NASA Astrophysics Data System (ADS)

Bourgin, D.; Courtin, S.; Haas, F.; Goasduff, A.; Stefanini, A. M.; Montagnoli, G.; Montanari, D.; Corradi, L.; Huiming, J.; Scarlassara, F.; Fioretto, E.; Simenel, C.; Rowley, N.; Szilner, S.; Mijatović, T.

2016-05-01

Fusion cross sections have been measured in the 40Ca + 58Ni and 40Ca + 64Ni systems at energies around and below the Coulomb barrier. The 40Ca beam was delivered by the XTU Tandem accelerator of the Laboratori Nazionali di Legnaro and evaporation residues were measured at very forward angles with the LNL electrostatic beam deflector. Coupled-channels calculations were performed which highlight possible strong effects of neutron transfers on the fusion below the barrier in the 40Ca + 64Ni system. Microscopic time-dependent Hartree-Fock calculations have also been performed for both systems. Preliminary results are shown.

10 CFR 63.113 - Performance objectives for the geologic repository after permanent closure.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 2 2014-01-01 2014-01-01 false Performance objectives for the geologic repository after permanent closure. 63.113 Section 63.113 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) DISPOSAL OF HIGH... and an engineered barrier system. (b) The engineered barrier system must be designed so that, working...

10 CFR 63.113 - Performance objectives for the geologic repository after permanent closure.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Performance objectives for the geologic repository after permanent closure. 63.113 Section 63.113 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) DISPOSAL OF HIGH... and an engineered barrier system. (b) The engineered barrier system must be designed so that, working...

10 CFR 63.113 - Performance objectives for the geologic repository after permanent closure.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Performance objectives for the geologic repository after permanent closure. 63.113 Section 63.113 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) DISPOSAL OF HIGH... and an engineered barrier system. (b) The engineered barrier system must be designed so that, working...

10 CFR 63.113 - Performance objectives for the geologic repository after permanent closure.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 2 2012-01-01 2012-01-01 false Performance objectives for the geologic repository after permanent closure. 63.113 Section 63.113 Energy NUCLEAR REGULATORY COMMISSION (CONTINUED) DISPOSAL OF HIGH... and an engineered barrier system. (b) The engineered barrier system must be designed so that, working...

Barriers to using eHealth data for clinical performance feedback in Malawi: A case study

PubMed Central

Landis-Lewis, Zach; Manjomo, Ronald; Gadabu, Oliver J; Kam, Matthew; Simwaka, Bertha N; Zickmund, Susan L; Chimbwandira, Frank; Douglas, Gerald P; Jacobson, Rebecca S

2016-01-01

Introduction Sub-optimal performance of healthcare providers in low-income countries is a critical and persistent global problem. The use of electronic health information technology (eHealth) in these settings is creating large-scale opportunities to automate performance measurement and provision of feedback to individual healthcare providers, to support clinical learning and behavior change. An electronic medical record system (EMR) deployed in 66 antiretroviral therapy clinics in Malawi collects data that supervisors use to provide quarterly, clinic-level performance feedback. Understanding barriers to provision of eHealth-based performance feedback for individual healthcare providers in this setting could present a relatively low-cost opportunity to significantly improve the quality of care. Objective The aims of this study were to identify and describe barriers to using EMR data for individualized audit and feedback for healthcare providers in Malawi and to consider how to design technology to overcome these barriers. Methods We conducted a qualitative study using interviews, observations, and informant feedback in eight public hospitals in Malawi where an EMR is used. We interviewed 32 healthcare providers and conducted seven hours of observation of system use. Results We identified four key barriers to the use of EMR data for clinical performance feedback: provider rotations, disruptions to care processes, user acceptance of eHealth, and performance indicator lifespan. Each of these factors varied across sites and affected the quality of EMR data that could be used for the purpose of generating performance feedback for individual healthcare providers. Conclusion Using routinely collected eHealth data to generate individualized performance feedback shows potential at large-scale for improving clinical performance in low-resource settings. However, technology used for this purpose must accommodate ongoing changes in barriers to eHealth data use. Understanding the clinical setting as a complex adaptive system (CAS) may enable designers of technology to effectively model change processes to mitigate these barriers. PMID:26238704

Retrofit of existing statewide Louisiana safety walk bridge barrier railing systems : research project capsule.

DOT National Transportation Integrated Search

2016-07-01

Currently, the Louisiana Department of Transportation and Development (DOTD) : maintains approximately 200 miles of concrete safety walk barrier railing systems on : its bridges. Some of these vintage systems do not meet the current crash performance...

PERMEABLE REACTIVE BARRIER PERFORMANCE MONITORING: LONG-TERM TRENDS IN GEOCHEMICAL PARAMETERS AT TWO SITES

EPA Science Inventory

A major goal of research on the long-term performance of subsurface reactive barriers is to identify standard ground water monitoring parameters that may be useful indicators of declining performance or impending system failure. Results are presented from ground water monitoring ...

PERMEABLE REACTIVE BARRIER PERFORMANCE MONITORING: LONG-TERM TRENDS IN GEOCHEMICAL PARAMETERS AT TWO SITES

EPA Science Inventory

A major goal of research on the long-term performance of subsurface reactive barriers is to identify standard ground-water monitoring parameters that may be useful indicators of declining performance or impending system failure. Results are presented from studies conducted over ...

Scientific evaluation of the ArmorGuard mobile barrier system.

DOT National Transportation Integrated Search

2011-06-17

"Accidents and injuries occur during maintenance activities that could be protected by the ArmorGuard or BalsiBeam mobile barrier systems. The main purpose of this study is to perform a scientific evaluation of the utility of the ArmorGuard system in...

Investigation of the Mechanical Performance of Compliant Thermal Barriers

NASA Technical Reports Server (NTRS)

DeMange, Jeffrey J.; Bott, Robert J.; Dunlap, Patrick H.

2011-01-01

Compliant thermal barriers play a pivotal role in the thermal protection systems of advanced aerospace vehicles. Both the thermal properties and mechanical performance of these barriers are critical in determining their successful implementation. Due to the custom nature of many thermal barriers, designers of advanced spacecraft have little guidance as to the design, selection, and implementation of these elements. As part of an effort to develop a more fundamental understanding of the interrelationship between thermal barrier design and performance, mechanical testing of thermal barriers was conducted. Two different types of thermal barriers with several core insulation density levels ranging from 62 to 141 kg/cu m were investigated. Room-temperature compression tests were conducted on samples to determine load performance and assess thermal barrier resiliency. Results showed that the loading behavior of these thermal barriers was similar to other porous, low-density, compliant materials, such as elastomeric foams. Additionally, the insulation density level had a significant non-linear impact on the stiffness and peak loads of the thermal barriers. In contrast, neither the thermal barrier type nor the level of insulation density significantly influenced the room-temperature resiliency of the samples.

New research opportunities for roadside safety barriers improvement

NASA Astrophysics Data System (ADS)

Cantisani, Giuseppe; Di Mascio, Paola; Polidori, Carlo

2017-09-01

Among the major topics regarding the protection of roads, restraint systems still represent a big opportunity in order to increase safety performances. When accidents happen, in fact, the infrastructure can substantially contribute to the reduction of consequences if its marginal spaces are well designed and/or effective restraint systems are installed there. Nevertheless, basic concepts and technology of road safety barriers have not significantly changed for the last two decades. The paper proposes a new approach to the study aimed to define possible enhancements of restraint safety systems performances, by using new materials and defining innovative design principles. In particular, roadside systems can be developed with regard to vehicle-barrier interaction, vehicle-oriented design (included low-mass and extremely low-mass vehicles), traffic suitability, user protection, working width reduction. In addition, thanks to sensors embedded into the barriers, it is also expected to deal with new challenges related to the guidance of automatic vehicles and I2V communication.

Creep Behavior of Hafnia and Ytterbium Silicate Environmental Barrier Coating Systems on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis J.; Harder, Bryan

2011-01-01

Environmental barrier coatings will play a crucial role in future advanced gas turbine engines because of their ability to significantly extend the temperature capability and stability of SiC/SiC ceramic matrix composite (CMC) engine components, thus improving the engine performance. In order to develop high performance, robust coating systems for engine components, appropriate test approaches simulating operating temperature gradient and stress environments for evaluating the critical coating properties must be established. In this paper, thermal gradient mechanical testing approaches for evaluating creep and fatigue behavior of environmental barrier coated SiC/SiC CMC systems will be described. The creep and fatigue behavior of Hafnia and ytterbium silicate environmental barrier coatings on SiC/SiC CMC systems will be reported in simulated environmental exposure conditions. The coating failure mechanisms will also be discussed under the heat flux and stress conditions.

MASH TL-4 crash testing and evaluation of the RESTORE barrier.

DOT National Transportation Integrated Search

2015-11-01

Three full-scale vehicle crash tests were conducted according to the MASH Test Level 4 (TL-4) safety performance criteria on a : restorable and reusable energy-absorbing roadside/median barrier, designated the RESTORE barrier. The system utilized for...

Engineered Barrier System: Physical and Chemical Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

P. Dixon

2004-04-26

The conceptual and predictive models documented in this Engineered Barrier System: Physical and Chemical Environment Model report describe the evolution of the physical and chemical conditions within the waste emplacement drifts of the repository. The modeling approaches and model output data will be used in the total system performance assessment (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. These models evaluate the range of potential water compositions within the emplacement drifts, resulting from the interaction of introduced materials and minerals in dust with water seeping into the drifts and with aqueous solutions forming bymore » deliquescence of dust (as influenced by atmospheric conditions), and from thermal-hydrological-chemical (THC) processes in the drift. These models also consider the uncertainty and variability in water chemistry inside the drift and the compositions of introduced materials within the drift. This report develops and documents a set of process- and abstraction-level models that constitute the engineered barrier system: physical and chemical environment model. Where possible, these models use information directly from other process model reports as input, which promotes integration among process models used for total system performance assessment. Specific tasks and activities of modeling the physical and chemical environment are included in the technical work plan ''Technical Work Plan for: In-Drift Geochemistry Modeling'' (BSC 2004 [DIRS 166519]). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system analysis model reports.« less

Application of CFRP with High Hydrogen Gas Barrier Characteristics to Fuel Tanks of Space Transportation System

NASA Astrophysics Data System (ADS)

Yonemoto, Koichi; Yamamoto, Yuta; Okuyama, Keiichi; Ebina, Takeo

In the future, carbon fiber reinforced plastics (CFRPs) with high hydrogen gas barrier performance will find wide applications in all industrial hydrogen tanks that aim at weight reduction; the use of such materials will be preferred to the use of conventional metallic materials such as stainless steel or aluminum. The hydrogen gas barrier performance of CFRP will become an important issue with the introduction of hydrogen-fuel aircraft. It will also play an important role in realizing fully reusable space transportation system that will have high specific tensile CFRP structures. Such materials are also required for the manufacture of high-pressure hydrogen gas vessels for use in the fuel cell systems of automobiles. This paper introduces a new composite concept that can be used to realize CFRPs with high hydrogen gas barrier performance for applications in the cryogenic tanks of fully reusable space transportation system by the incorporation of a nonmetallic crystal layer, which is actually a dense and highly oriented clay crystal laminate. The preliminary test results show that the hydrogen gas barrier characteristics of this material after cryogenic heat shocks and cyclic loads are still better than those of other polymer materials by approximately two orders of magnitude.

Evaluation of Subsurface Engineered Barriers at Waste Sites Volumes 1 and 2

EPA Pesticide Factsheets

This report provides the U.S. Environmental Protection Agency’s (EPA) waste programs with a national retrospective analysis of barrier field performance, as well as information that useful in developing guidance on the use and evaluation of barrier systems

PERFORMANCE EVALUATION OF A CARBON-BASED REACTIVE BARRIER FOR NITRATE REMEDIATION

EPA Science Inventory

Nitrate (NO3-) is a common ground water contaminant related to agricultural activity, waste water disposal, leachate from landfills, septic systems, and industrial processes. This study reports on the performance of a carbon-based permeable reactive barrier (PRB) that was constr...

CRASH TEST AND EVALUATION OF RESTRAINED SAFETY-SHAPE CONCRETE BARRIERS ON CONCRETE BRIDGE DECK

DOT National Transportation Integrated Search

2018-01-01

This research designed and tested a new portable concrete barrier that meets the performance of MASH TL-4 and can be used in temporary and permanent applications on bridge decks. Additionally, this new barrier system will minimize deflection, allowin...

Current-induced changes of migration energy barriers in graphene and carbon nanotubes

NASA Astrophysics Data System (ADS)

Obodo, J. T.; Rungger, I.; Sanvito, S.; Schwingenschlögl, U.

2016-05-01

An electron current can move atoms in a nanoscale device with important consequences for the device operation and breakdown. We perform first principles calculations aimed at evaluating the possibility of changing the energy barriers for atom migration in carbon-based systems. In particular, we consider the migration of adatoms and defects in graphene and carbon nanotubes. Although the current-induced forces are large for both the systems, in graphene the force component along the migration path is small and therefore the barrier height is little affected by the current flow. In contrast, the same barrier is significantly reduced in carbon nanotubes as the current increases. Our work also provides a real-system numerical demonstration that current-induced forces within density functional theory are non-conservative.An electron current can move atoms in a nanoscale device with important consequences for the device operation and breakdown. We perform first principles calculations aimed at evaluating the possibility of changing the energy barriers for atom migration in carbon-based systems. In particular, we consider the migration of adatoms and defects in graphene and carbon nanotubes. Although the current-induced forces are large for both the systems, in graphene the force component along the migration path is small and therefore the barrier height is little affected by the current flow. In contrast, the same barrier is significantly reduced in carbon nanotubes as the current increases. Our work also provides a real-system numerical demonstration that current-induced forces within density functional theory are non-conservative. Electronic supplementary information (ESI) available. See DOI: 10.1039/C6NR00534A

Overcoming barriers to high performance seismic design using lessons learned from the green building industry

NASA Astrophysics Data System (ADS)

Glezil, Dorothy

NEHRP's Provisions today currently governing conventional seismic resistant design. These provisions, though they ensure the life-safety of building occupants, extensive damage and economic losses may still occur in the structures. This minimum performance can be enhanced using the Performance-Based Earthquake Engineering methodology and passive control systems like base isolation and energy dissipation systems. Even though these technologies and the PBEE methodology are effective reducing economic losses and fatalities during earthquakes, getting them implemented into seismic resistant design has been challenging. One of the many barriers to their implementation has been their upfront costs. The green building community has faced some of the same challenges that the high performance seismic design community currently faces. The goal of this thesis is to draw on the success of the green building industry to provide recommendations that may be used overcome the barriers that high performance seismic design (HPSD) is currently facing.

Thermal model of attic systems with radiant barriers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilkes, K.E.

This report summarizes the first phase of a project to model the thermal performance of radiant barriers. The objective of this phase of the project was to develop a refined model for the thermal performance of residential house attics, with and without radiant barriers, and to verify the model by comparing its predictions against selected existing experimental thermal performance data. Models for the thermal performance of attics with and without radiant barriers have been developed and implemented on an IBM PC/AT computer. The validity of the models has been tested by comparing their predictions with ceiling heat fluxes measured inmore » a number of laboratory and field experiments on attics with and without radiant barriers. Cumulative heat flows predicted by the models were usually within about 5 to 10 percent of measured values. In future phases of the project, the models for attic/radiant barrier performance will be coupled with a whole-house model and further comparisons with experimental data will be made. Following this, the models will be utilized to provide an initial assessment of the energy savings potential of radiant barriers in various configurations and under various climatic conditions. 38 refs., 14 figs., 22 tabs.« less

ENVIRONMENTAL RESEARCH BRIEF: LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS USING ZERO-VALENT IRON: AN EVALUATION AT TWO SITES

EPA Science Inventory

Geochemical and microbiological factors that control long-term performance of subsurface permeable reactive barriers were evaluated at the Elizabeth City, NC and the Denver Federal Center, CO sites. These groundwater treatment systems use zero-valent iron filings to intercept an...

Analytical investigation of thermal barrier coatings for advanced power generation combustion turbines

NASA Technical Reports Server (NTRS)

Amos, D. J.

1977-01-01

An analytical evaluation was conducted to determine quantitatively the improvement potential in cycle efficiency and cost of electricity made possible by the introduction of thermal barrier coatings to power generation combustion turbine systems. The thermal barrier system, a metallic bond coat and yttria stabilized zirconia outer layer applied by plasma spray techniques, acts as a heat insulator to provide substantial metal temperature reductions below that of the exposed thermal barrier surface. The study results show the thermal barrier to be a potentially attractive means for improving performance and reducing cost of electricity for the simple, recuperated, and combined cycles evaluated.

The Effect of Core Configuration on Thermal Barrier Thermal Performance

NASA Technical Reports Server (NTRS)

DeMange, Jeffrey J.; Bott, Robert H.; Druesedow, Anne S.

2015-01-01

Thermal barriers and seals are integral components in the thermal protection systems (TPS) of nearly all aerospace vehicles. They are used to minimize heat transfer through interfaces and gaps and protect underlying temperature-sensitive components. The core insulation has a significant impact on both the thermal and mechanical properties of compliant thermal barriers. Proper selection of an appropriate core configuration to mitigate conductive, convective and radiative heat transfer through the thermal barrier is challenging. Additionally, optimization of the thermal barrier for thermal performance may have counteracting effects on mechanical performance. Experimental evaluations have been conducted to better understand the effect of insulation density on permeability and leakage performance, which can significantly impact the resistance to convective heat transfer. The effect of core density on mechanical performance was also previously investigated and will be reviewed. Simple thermal models were also developed to determine the impact of various core parameters on downstream temperatures. An extended understanding of these factors can improve the ability to design and implement these critical TPS components.

Global interrupt and barrier networks

DOEpatents

Blumrich, Matthias A.; Chen, Dong; Coteus, Paul W.; Gara, Alan G.; Giampapa, Mark E; Heidelberger, Philip; Kopcsay, Gerard V.; Steinmacher-Burow, Burkhard D.; Takken, Todd E.

2008-10-28

A system and method for generating global asynchronous signals in a computing structure. Particularly, a global interrupt and barrier network is implemented that implements logic for generating global interrupt and barrier signals for controlling global asynchronous operations performed by processing elements at selected processing nodes of a computing structure in accordance with a processing algorithm; and includes the physical interconnecting of the processing nodes for communicating the global interrupt and barrier signals to the elements via low-latency paths. The global asynchronous signals respectively initiate interrupt and barrier operations at the processing nodes at times selected for optimizing performance of the processing algorithms. In one embodiment, the global interrupt and barrier network is implemented in a scalable, massively parallel supercomputing device structure comprising a plurality of processing nodes interconnected by multiple independent networks, with each node including one or more processing elements for performing computation or communication activity as required when performing parallel algorithm operations. One multiple independent network includes a global tree network for enabling high-speed global tree communications among global tree network nodes or sub-trees thereof. The global interrupt and barrier network may operate in parallel with the global tree network for providing global asynchronous sideband signals.

Underutilization of Mental Health Services among College Students: An Examination of System-Related Barriers

ERIC Educational Resources Information Center

Marsh, Carey N.; Wilcoxon, S. Allen

2015-01-01

Despite the documented benefits of counseling and mental health services on academic performance and degree attainment, only about 10% of psychologically distressed college students ever seek professional help. This investigation examined mental health care system-related barriers that might distinguish help seekers from nonhelp seekers among…

Thick thermal barrier coatings for diesel engines

NASA Technical Reports Server (NTRS)

Beardsley, M. Brad

1995-01-01

Caterpillar's approach to applying thick thermal barrier coatings (TTBC's) to diesel engine combustion chambers has been to use advanced modeling techniques to predict engine conditions and combine this information with fundamental property evaluation of TTBC systems to predict engine performance and TTBC stress states. Engine testing has been used to verify the predicted performance of the TTBC systems and provide information on failure mechanisms. The objective Caterpillar's program to date has been to advance the fundamental understanding of thick thermal barrier coating systems. Previous reviews of thermal barrier coating technology concluded that the current level of understanding of coating system behavior is inadequate and the lack of fundamental understanding may impeded the application of TTBC's to diesel engines. Areas of TTBC technology being examined in this program include powder characteristics and chemistry; bond coat composition; coating design, microstructure, and thickness as they affect properties, durability, and reliability; and TTBC 'aging' effects (microstructural and property changes) under diesel engine operating conditions. Methods to evaluate the reliability and durability of TTBC's have been developed that attempt to understand the fundamental strength of TTBC's for particular stress states.

Thick thermal barrier coatings for diesel engines

NASA Technical Reports Server (NTRS)

Beardsley, M. B.

1995-01-01

Caterpillar's approach to applying Thick Thermal Barrier Coatings (TTBC's) to diesel engine combustion chambers has been to use advanced modeling techniques to predict engine conditions and combine this information with fundamental property evaluation of TTBC systems to predict engine performance and TTBC stress states. Engine testing has been used to verify the predicted performance of the TTBC systems and provide information on failure mechanisms. The objective of Caterpillar's subcontract with ORNL is to advance the fundamental understanding of thick thermal barrier coating systems. Previous reviews of thermal barrier coating technology concluded that the current level of understanding of coating system behavior is inadequate and the lack of fundamental understanding may impede the application of TTBC's to diesel engines. Areas of TTBC technology being examined in this program include powder characteristics and chemistry; bond coat composition; coating design, microstructure, and thickness as they affect properties, durability, and reliability; and TTBC 'aging' effects (microstructural and property changes) under diesel engine operating conditions. Methods to evaluate the reliability and durability of TTBC's have been developed that attempt to understand the fundamental strength of TTBC's for particular stress states.

Perceived barriers to effective implementation of public reporting of hospital performance data in Australia: a qualitative study.

PubMed

Canaway, Rachel; Bismark, Marie; Dunt, David; Kelaher, Margaret

2017-06-07

Public reporting of government funded (public) hospital performance data was mandated in Australia in 2011. Studies suggest some benefit associated with such public reporting, but also considerable scope to improve reporting systems. In 2015, a purposive sample of 41 expert informants were interviewed, representing consumer, provider and purchasers perspectives across Australia's public and private health sectors, to ascertain expert opinion on the utility and impact of public reporting of health service performance. Qualitative data was thematically analysed with a focus on reporting perceived strengths and barriers to public reporting of hospital performance data (PR). Many more weaknesses and barriers to PR were identified than strengths. Barriers were: conceptual (unclear objective, audience and reporting framework); systems-level (including lack of consumer choice, lack of consumer and clinician involvement, jurisdictional barriers, lack of mandate for private sector reporting); technical and resource related (including data complexity, lack of data relevance consistency, rigour); and socio-cultural (including provider resistance to public reporting, poor consumer health literacy, lack of consumer empowerment). Perceptions of the Australian experience of PR highlight important issues in its implementation that can provide lessons for Australia and elsewhere. A considerable weakness of PR in Australia is that the public are often not considered its major audience, resulting in information ineffectually framed to meet the objective of PR informing consumer decision-making about treatment options. Greater alignment is needed between the primary objective of PR, its audience and audience needs; more than one system of PR might be necessary to meet different audience needs and objectives. Further research is required to assess objectively the potency of the barriers to PR suggested by our panel of informants.

Development of Advanced Environmental Barrier Coatings for SiC/SiC Composites at NASA GRC: Prime-Reliant Design and Durability Perspectives

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2017-01-01

Environmental barrier coatings (EBCs) are considered technologically important because of the critical needs and their ability to effectively protect the turbine hot-section SiC/SiC ceramic matrix composite (CMC) components in harsh engine combustion environments. The development of NASA's advanced environmental barrier coatings have been aimed at significantly improved the coating system temperature capability, stability, erosion-impact, and CMAS resistance for SiC/SiC turbine airfoil and combustors component applications. The NASA environmental barrier coating developments have also emphasized thermo-mechanical creep and fatigue resistance in simulated engine heat flux and environments. Experimental results and models for advanced EBC systems will be presented to help establishing advanced EBC composition design methodologies, performance modeling and life predictions, for achieving prime-reliant, durable environmental coating systems for 2700-3000 F engine component applications. Major technical barriers in developing environmental barrier coating systems and the coating integration with next generation composites having further improved temperature capability, environmental stability, EBC-CMC fatigue-environment system durability will be discussed.

Design and Performance Optimizations of Advanced Erosion-Resistant Low Conductivity Thermal Barrier Coatings for Rotorcraft Engines

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

2012-01-01

Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future rotorcraft engine higher fuel efficiency and lower emission goals. For thermal barrier coatings designed for rotorcraft turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability, because the rotorcraft are often operated in the most severe sand erosive environments. Advanced low thermal conductivity and erosion-resistant thermal barrier coatings are being developed, with the current emphasis being placed on thermal barrier coating toughness improvements using multicomponent alloying and processing optimization approaches. The performance of the advanced thermal barrier coatings has been evaluated in a high temperature erosion burner rig and a laser heat-flux rig to simulate engine erosion and thermal gradient environments. The results have shown that the coating composition and architecture optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic oxidation durability

10 CFR 60.113 - Performance of particular barriers after permanent closure.

Code of Federal Regulations, 2011 CFR

2011-01-01

... the engineered barrier system are dominated by fission product decay; and (B) any release of... the time during which the thermal pulse is dominated by the decay heat from the fission products; (3...

10 CFR 60.113 - Performance of particular barriers after permanent closure.

Code of Federal Regulations, 2010 CFR

2010-01-01

... the engineered barrier system are dominated by fission product decay; and (B) any release of... the time during which the thermal pulse is dominated by the decay heat from the fission products; (3...

Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna; Kiser, Doug; Wiesner, Valerie L.

2016-01-01

This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiCSiC Ceramic Matrix Composite (CMC) components for next generation turbine engines. The emphasis has been placed on the current design challenges of the 2700F environmental barrier coatings; coating processing and integration with SiCSiC CMCs and component systems; and performance evaluation and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements through advanced compositions and architecture designs, as shown in recent simulated engine high heat flux, combustion environment, in conjunction with mechanical creep and fatigue loading testing conditions.

Thermal and Environmental Barrier Coatings for Advanced Propulsion Engine Systems

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Miller, Robert A.

2004-01-01

Ceramic thermal and environmental barrier coatings (TEBCs) are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments, and extend component lifetimes. For future high performance engines, the development of advanced ceramic barrier coating systems will allow these coatings to be used to simultaneously increase engine operating temperature and reduce cooling requirements, thereby leading to significant improvements in engine power density and efficiency. In order to meet future engine performance and reliability requirements, the coating systems must be designed with increased high temperature stability, lower thermal conductivity, and improved thermal stress and erosion resistance. In this paper, ceramic coating design and testing considerations will be described for high temperature and high-heat-flux engine applications in hot corrosion and oxidation, erosion, and combustion water vapor environments. Further coating performance and life improvements will be expected by utilizing advanced coating architecture design, composition optimization, and improved processing techniques, in conjunction with modeling and design tools.

Performance and Durability of Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna

2016-01-01

This presentation highlights advanced environmental barrier coating (EBC) and SiC-SiC Ceramic Matrix Composites (CMC) systems for next generation turbine engines. The emphasis will be placed on fundamental coating and CMC property evaluations; and the integrated system performance and degradation mechanisms in simulated laboratory turbine engine testing environments. Long term durability tests in laser rig simulated high heat flux the rmomechanical creep and fatigue loading conditions will also be presented. The results can help improve the future EBC-CMC system designs, validating the advanced EBC-CMC technologies for hot section turbine engine applications.

Performance evaluation of cable median barrier systems in Texas.

DOT National Transportation Integrated Search

2009-08-01

Since 2003, the Texas Department of Transportation (TxDOT) has embarked on an aggressive campaign to install : median barriers to prevent cross-median crashes on freeway facilities statewide. In the few years prior to 2003, : virtually all fatalities...

Application of dimensional analysis to predict the performance of rockfall barrier

NASA Astrophysics Data System (ADS)

Spadari, M.; Giacomini, A.; Buzzi, O.; Hambleton, J.

2012-04-01

Natural hazards involving rocks or rock slopes are responsible for loss of life and damage to infrastructure and are consequently widely studied. Rock fall barriers are a common type of protection structures that is usually designed on the basis of total impact energy. However, the systems are usually tested in free fall where the predominant component of energy is kinematic and it has been shown that there is not a unique relationship between the response of a barrier and the kinetic energy of the impacting block. In particular, recent studies have discussed the so called "bullet effect" i.e. relatively small blocks traveling at high speed can perforate the barriers yet having acceptable level of energy. This effect compromises the use of kinetic energy as an adequate design criterion since there is not a threshold value defining clearly acceptable and unacceptable values of energy. This issue can be addressed empirically by using different block sizes when it comes to test a system. However, the literature still lacks a characterization of a rockfall barrier performance regarding the bullet effect. This note presents the results of the application of dimensional analysis to the physical problem of the bullet effect. This latter has been formulated as a function involving eight key variables: v = f(ρ, K, σy, H, A, Db,Dw) where v is the minimum speed of a given block to break the barrier, ρgs the density of the block, Kis the stiffness of the system, σy is the strength of the wires, H is the height of the barrier, A is the aperture of the mesh, Db is the dimension of the block and Dw is the diameter of the wire. Applying the Buckingham Pi theorem allows reducing the equation above to a simpler problem involving only three dimensionless parameters: E*=F(S*, G*) Where E* is the performance parameter, S* is the strength-stiffness parameter and G* is the geometrical parameters defined as: E*= (ρ.v2.H)/K S*=K/(H.gσy) And G*=A-0.25.Db-0.75.Db F in the simplified equation is referred to as the Rockfall Barrier Performance, or RoBaP, Model. Results suggest that the dimensional analysis can satisfactorily be used to assess the performance of a barrier when impacted by variable block size. A calibration-prediction exercise has been conducted using data form the literature to assess the predictive capability of the RoBaP model. It has been found that the RoBaP model gives satisfactory results. In particular, the progressive loss of performance of the rock fall barrier as the block size diminishes has been well captured.

200-BP-1 Prototype Hanford Barrier -- 15 Years of Performance Monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, Anderson L.; Draper, Kathryn E.; Link, Steven O.

2011-09-30

Monitoring is an essential component of engineered barrier system design and operation. A composite capacitive cover, including a capillary break and an evapotranspiration (ET) barrier at the Hanford Site, is generating data that can be used to help resolve these issues. The prototype Hanford barrier was constructed over the 216-B-57 Crib in 1994 to evaluate surface-barrier constructability, construction costs, and physical and hydrologic performance at the field scale. The barrier has been routinely monitored between November 1994 and September 1998 as part of a Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) treatability test of barrier performance formore » the 200 BP 1 Operable Unit. Since FY 1998, monitoring has focused on a more limited set of key water balance, stability, and biotic parameters. In FY 2009, data collection was focused on: (1) water-balance monitoring, consisting of precipitation, runoff, soil moisture storage, and drainage measurements with evapotranspiration calculated by difference; (2) stability monitoring, consisting of asphalt-layer-settlement, basalt-side-slope-stability, and surface-elevation measurements; (3) vegetation dynamics; and (4) animal use. September 2009 marked 15 years since the start of monitoring and the collection of performance data. This report describes the results of monitoring activities during the period October 1, 2008, through September 30, 2009, and summarizes the 15 years of performance data collected from September 1994 through September 2009.« less

Optimistic barrier synchronization

NASA Technical Reports Server (NTRS)

Nicol, David M.

1992-01-01

Barrier synchronization is fundamental operation in parallel computation. In many contexts, at the point a processor enters a barrier it knows that it has already processed all the work required of it prior to synchronization. The alternative case, when a processor cannot enter a barrier with the assurance that it has already performed all the necessary pre-synchronization computation, is treated. The problem arises when the number of pre-sychronization messages to be received by a processor is unkown, for example, in a parallel discrete simulation or any other computation that is largely driven by an unpredictable exchange of messages. We describe an optimistic O(log sup 2 P) barrier algorithm for such problems, study its performance on a large-scale parallel system, and consider extensions to general associative reductions as well as associative parallel prefix computations.

Engineered Barrier System performance requirements systems study report. Revision 02

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balady, M.A.

This study evaluates the current design concept for the Engineered Barrier System (EBS), in concert with the current understanding of the geologic setting to assess whether enhancements to the required performance of the EBS are necessary. The performance assessment calculations are performed by coupling the EBS with the geologic setting based on the models (some of which were updated for this study) and assumptions used for the 1995 Total System Performance Assessment (TSPA). The need for enhancements is determined by comparing the performance assessment results against the EBS related performance requirements. Subsystem quantitative performance requirements related to the EBS includemore » the requirement to allow no more than 1% of the waste packages (WPs) to fail before 1,000 years after permanent closure of the repository, as well as a requirement to control the release rate of radionuclides from the EBS. The EBS performance enhancements considered included additional engineered components as well as evaluating additional performance available from existing design features but for which no performance credit is currently being taken.« less

Analysis of developed transition road safety barrier systems.

PubMed

Soltani, Mehrtash; Moghaddam, Taher Baghaee; Karim, Mohamed Rehan; Sulong, N H Ramli

2013-10-01

Road safety barriers protect vehicles from roadside hazards by redirecting errant vehicles in a safe manner as well as providing high levels of safety during and after impact. This paper focused on transition safety barrier systems which were located at the point of attachment between a bridge and roadside barriers. The aim of this study was to provide an overview of the behavior of transition systems located at upstream bridge rail with different designs and performance levels. Design factors such as occupant risk and vehicle trajectory for different systems were collected and compared. To achieve this aim a comprehensive database was developed using previous studies. The comparison showed that Test 3-21, which is conducted by impacting a pickup truck with speed of 100 km/h and angle of 25° to transition system, was the most severe test. Occupant impact velocity and ridedown acceleration for heavy vehicles were lower than the amounts for passenger cars and pickup trucks, and in most cases higher occupant lateral impact ridedown acceleration was observed on vehicles subjected to higher levels of damage. The best transition system was selected to give optimum performance which reduced occupant risk factors using the similar crashes in accordance with Test 3-21. Copyright © 2013 Elsevier Ltd. All rights reserved.

Development of Advanced Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites: Path Toward 2700 F Temperature Capability and Beyond

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Good, Brian; Costa, Gustavo; Bhatt, Ramakrishna T.; Fox, Dennis S.

2017-01-01

Advanced environmental barrier coating systems for SiC-SiC Ceramic Matrix Composite (CMC) turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant coating development challenges is to achieve prime-reliant environmental barrier coating systems to meet the future 2700F EBC-CMC temperature stability and environmental durability requirements. This presentation will emphasize recent NASA environmental barrier coating system testing and down-selects, particularly the development path and properties towards 2700-3000F durability goals by using NASA hafnium-hafnia-rare earth-silicon-silicate composition EBC systems for the SiC-SiC CMC turbine component applications. Advanced hafnium-based compositions for enabling next generation EBC and CMCs capabilities towards ultra-high temperature ceramic coating systems will also be briefly mentioned.

Development and Life Prediction of Erosion Resistant Turbine Low Conductivity Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

2010-01-01

Future rotorcraft propulsion systems are required to operate under highly-loaded conditions and in harsh sand erosion environments, thereby imposing significant material design and durability issues. The incorporation of advanced thermal barrier coatings (TBC) in high pressure turbine systems enables engine designs with higher inlet temperatures, thus improving the engine efficiency, power density and reliability. The impact and erosion resistance of turbine thermal barrier coating systems are crucial to the turbine coating technology application, because a robust turbine blade TBC system is a prerequisite for fully utilizing the potential coating technology benefit in the rotorcraft propulsion. This paper describes the turbine blade TBC development in addressing the coating impact and erosion resistance. Advanced thermal barrier coating systems with improved performance have also been validated in laboratory simulated engine erosion and/or thermal gradient environments. A preliminary life prediction modeling approach to emphasize the turbine blade coating erosion is also presented.

The Development of Erosion and Impact Resistant Turbine Airfoil Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

2007-01-01

Thermal barrier coatings are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments and extend component lifetimes. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Advanced erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the doped thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion and impact damage mechanisms of the thermal barrier coatings will also be discussed.

Computational design and experimental validation of new thermal barrier systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Shengmin

2015-03-31

The focus of this project is on the development of a reliable and efficient ab initio based computational high temperature material design method which can be used to assist the Thermal Barrier Coating (TBC) bond-coat and top-coat design. Experimental evaluations on the new TBCs are conducted to confirm the new TBCs’ properties. Southern University is the subcontractor on this project with a focus on the computational simulation method development. We have performed ab initio density functional theory (DFT) method and molecular dynamics simulation on screening the top coats and bond coats for gas turbine thermal barrier coating design and validationmore » applications. For experimental validations, our focus is on the hot corrosion performance of different TBC systems. For example, for one of the top coatings studied, we examined the thermal stability of TaZr 2.75O 8 and confirmed it’s hot corrosion performance.« less

Durability and CMAS Resistance of Advanced Environmental Barrier Coatings Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2015-01-01

Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. This paper will emphasize advanced environmental barrier coating developments for SiCSiC turbine airfoil components, by using advanced coating compositions and processing, in conjunction with mechanical and environment testing and durability validations. The coating-CMC degradations and durability in the laboratory simulated engine fatigue-creep and complex operating environments are being addressed. The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will be discussed. The results help understand the advanced EBC-CMC system performance, aiming at the durability improvements of more robust, prime-reliant environmental barrier coatings for successful applications of the component technologies and lifing methodologies.

Microstructure Evolution and Durability of Advanced Environmental Barrier Coating Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Evans, Laura J.; McCue, Terry R.; Harder, Bryan

2016-01-01

Environmental barrier coated SiC-SiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. Advanced HfO2 and rare earth silicate environmental barrier coatings (EBCs), along with multicomponent hafnium and rare earth silicide EBC bond coats have been developed. The coating degradation mechanisms in the laboratory simulated engine thermal cycling, and fatigue-creep operating environments are also being investigated. This paper will focus on the microstructural and compositional evolutions of an advanced environmental barrier coating system on a SiC-SiC CMC substrate during the high temperature simulated durability tests, by using a Field Emission Gun Scanning Electron Microscopy, Energy Dispersive Spectroscopy (EDS) and Wavelength Dispersive Spectroscopy (WDS). The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will also be discussed. The detailed analysis results help understand the EBC-CMC system performance, aiming at the durability improvements to achieve more robust, prime-reliant environmental barrier coatings.

Asymmetric reproductive barriers and mosaic reproductive isolation: insights from Misty lake–stream stickleback

PubMed Central

Räsänen, Katja; Hendry, Andrew P

2014-01-01

Ecological speciation seems to occur readily but is clearly not ubiquitous – and the relative contributions of different reproductive barriers remain unclear in most systems. We here investigate the potential importance of selection against migrants in lake/stream stickleback (Gasterosteus aculeatus) from the Misty Lake system, Canada. This system is of particular interest because one population contrast (Lake vs. Outlet stream) shows very low genetic and morphological divergence, whereas another population contrast (Lake vs. Inlet stream) shows dramatic genetic and morphological divergence apparently without strong and symmetric reproductive barriers. To test whether selection against migrants might solve this “conundrum of missing reproductive isolation”, we performed a fully factorial reciprocal transplant experiment using 225 individually marked stickleback collected from the wild. Relative fitness of the different ecotypes (Lake, Inlet, and Outlet) was assessed based on survival and mass change in experimental enclosures. We found that Inlet fish performed poorly in the lake (selection against migrants in that direction), whereas Lake fish outperformed Inlet fish in all environments (no selection against migrants in the opposite direction). As predicted from their phenotypic and genetic similarity, Outlet and Lake fish performed similarly in all environments. These results suggest that selection against migrants is asymmetric and, together with previous work, indicates that multiple reproductive barriers contribute to reproductive isolation. Similar mosaic patterns of reproductive isolation are likely in other natural systems. PMID:24772291

Social, ethical and legal barriers to e-health.

PubMed

Anderson, James G

2007-01-01

Information technology such as electronic medical records (EMRs), electronic prescribing and decision support systems are recognized as essential tools in Europe, the U.S., Canada, Australia, and New Zealand. But significant barriers impede wide-scale adoption of these tools, especially EMR systems. The objectives of this study were to investigate the present status of information technology in health care, the perceived benefits and barriers by primary care physicians. Literature analysis and survey data from primary care physicians on adoption of information technology are reviewed. The U.S. trails European countries as well as Canada, Australia and New Zealand in the use of information technology in primary care. The results of the study indicate that physicians in general perceive benefits to information technology, but also cite major barriers to its implementation in their practices. These barriers include lack of access to capital by health care providers, complex systems and lack of data standards that permit exchange of clinical data, privacy concerns and legal barriers. Overcoming these barriers will require subsidies and performance incentives by payers and government; certification and standardization of vendor applications that permit clinical data exchange; removal of legal barriers; and greater security of medical data to convince practitioners and patients of the value of EMRs.

High Pressure Burner Rig Testing of Advanced Environmental Barrier Coatings for Si3N4 Turbine Components

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Pastel, Robert T.

2007-01-01

Advanced thermal and environmental barrier coatings are being developed for Si3N4 components for turbine engine propulsion applications. High pressure burner rig testing was used to evaluate the coating system performance and durability. Test results demonstrated the feasibility and durability of the coating component systems under the simulated engine environments.

Current-induced changes of migration energy barriers in graphene and carbon nanotubes.

PubMed

Obodo, J T; Rungger, I; Sanvito, S; Schwingenschlögl, U

2016-05-21

An electron current can move atoms in a nanoscale device with important consequences for the device operation and breakdown. We perform first principles calculations aimed at evaluating the possibility of changing the energy barriers for atom migration in carbon-based systems. In particular, we consider the migration of adatoms and defects in graphene and carbon nanotubes. Although the current-induced forces are large for both the systems, in graphene the force component along the migration path is small and therefore the barrier height is little affected by the current flow. In contrast, the same barrier is significantly reduced in carbon nanotubes as the current increases. Our work also provides a real-system numerical demonstration that current-induced forces within density functional theory are non-conservative.

Dissolved organic matter effects on the performance of a barrier to polycyclic aromatic hydrocarbon transport by groundwater

NASA Astrophysics Data System (ADS)

Moon, Jung-Won; Goltz, Mark N.; Ahn, Kyu-Hong; Park, Jae-Woo

2003-02-01

In order to contain the movement of organic contaminants in groundwater, a subsurface sorption barrier consisting of sand or clay minerals coated with a cationic surfactant has been proposed. The effectiveness of such a sorption barrier might be affected by the presence of dissolved organic matter (DOM) in the groundwater. To study the impact of DOM on barrier performance, a series of batch experiments were performed by measuring naphthalene and phenanthrene sorption onto sand coated with cetylpyridinium chloride (CPC) and bentonite coated with hexadecyltrimethylammonium bromide (HDTMA) in the presence of various concentrations of DOM. The overall soil-water distribution coefficient ( K*) of naphthalene and phenanthrene onto CPC-coated sand decreased with increasing DOM concentration, whereas the K* of the compounds onto HDTMA-coated bentonite slightly increased with increasing DOM concentration. To describe the overall distribution of polycyclic aromatic hydrocarbons (PAHs) in the systems, a competitive multiphase sorption (CMS) model was developed and compared with an overall mechanistic sorption (OMS) model. The modeling studies showed that while the OMS model did not explain the CPC-coated sand experimental results, a model that included competitive sorption between DOM and PAH did. The experimental results and the modeling study indicated that there was no apparent competition between DOM and PAH in the HDTMA-coated bentonite system, and indicated that in groundwater systems with high DOM, a barrier using HDTMA-coated bentonite might be more effective.

Barrier infrared detector research at the Jet Propulsion Laboratory

NASA Astrophysics Data System (ADS)

Ting, David Z.; Keo, Sam A.; Liu, John K.; Mumolo, Jason M.; Khoshakhlagh, Arezou; Soibel, Alexander; Nguyen, Jean; Höglund, Linda; Rafol, B., , Sir; Hill, Cory J.; Gunapala, Sarath D.

2012-10-01

The barrier infrared detector device architecture offers the advantage of reduced dark current resulting from suppressed Shockley-Read-Hall (SRH) recombination and surface leakage. The versatility of the antimonide material system, with the availability of three different types of band offsets for flexibility in device design, provides the ideal setting for implementing barrier infrared detectors. We describe the progress made at the NASA Jet Propulsion Laboratory in recent years in Barrier infrared detector research that resulted in high-performance quantum structure infrared detectors, including the type-II superlattice complementary barrier infrared detector (CBIRD), and the high operating quantum dot barrier infrared detector (HOT QD-BIRD).

Reactive barrier system for nitrate removal from mine effluents in northern Sweden: Laboratory experiments

NASA Astrophysics Data System (ADS)

Herbert, Roger

2010-05-01

Laboratory column experiments have been conducted to determine nitrate removal rates from mine effluents by denitrification, with the purpose of providing initial data for the construction of a pilot scale reactive barrier system at the Malmberget iron mine, Sweden. Experiments were conducted at several different flow rates at 5C, 10C and room temperature; annual mean temperatures at the Malmberget site lie close to 0C. Columns were filled with an organic substrate consisting of sawdust mixed with sewage sludge, the source of denitrifying bacteria, supported by oven-dried clay pellets. Apparent denitrification rates, calculated from inflow and outflow nitrate concentrations and column hydraulic residence time, ranged from 5 to 13 mg N/L/d, with the lowest rates corresponding to the 5C experiments. These rates are, however, limited to a certain degree by the low flow rate and the supply of electrons acceptors (i.e. nitrate) to denitrifying bacteria. Results from the column experiment have been used to construct a barrier system in Malmberget, Sweden. Trial runs with the pilot-scale barrier will be conducted during 2010, with the purpose of determining the performance of the barrier as mean air temperatures increase from below to above 0C and saturated flow commences in the barrier. The barrier system is constructed as a rectangular container with steel sheet walls (9m length in flow direction, 1.5m deep), and the flow rate will be adjusted to a hydraulic residence time of 1 day. The pilot-scale barrier system currently lies above ground, but a permanent barrier system would be installed below the ground surface so that the system can be maintained at positive temperatures throughout the year.

Integrated evaluation of the performance of a more than seven year old permeable reactive barrier at a site contaminated with chlorinated aliphatic hydrocarbons (CAHs)

NASA Astrophysics Data System (ADS)

Muchitsch, Nanna; Van Nooten, Thomas; Bastiaens, Leen; Kjeldsen, Peter

2011-11-01

An important issue of concern for permeable reactive iron barriers is the long-term efficiency of the barriers due to the long operational periods required. Mineral precipitation resulting from the anaerobic corrosion of the iron filings and bacteria present in the barrier may play an important role in the long-term performance. An integrated study was performed on the Vapokon permeable reactive barrier (PRB) in Denmark by groundwater and iron core sample characterization. The detailed field groundwater sampling carried out from more than 75 well screens up and downstream the barrier showed a very efficient removal (> 99%) for the most important CAHs (PCE, TCE and 1,1,1-TCA). However, significant formation of cis-DCE within the PRB resulted in an overall insufficient efficiency for cis-DCE removal. The detailed analysis of the upstream groundwater revealed a very heterogeneous spatial distribution of contaminant loading into the PRB, which resulted in that only about a quarter of the barrier system is treating significant loads of CAHs. Laboratory batch experiments using contaminated groundwater from the site and iron material from the core samples revealed that the aged iron material performed equally well as virgin granular iron of the same type based on determined degradation rates despite that parts of the cored iron material were covered by mineral precipitates (especially iron sulfides, carbonate green rust and aragonite). The PCR analysis performed on the iron core samples indicated the presence of a microbial consortium in the barrier. A wide range of species were identified including sulfate and iron reducing bacteria, together with Dehalococcoides and Desulfuromonas species indicating microbial reductive dehalogenation potential. The microbes had a profound effect on the performance of the barrier, as indicated by significant degradation of dichloromethane (which is typically unaffected by zero valent iron) within the barrier.

Development of a continuous motorcycle protection barrier system using computer simulation and full-scale crash testing.

PubMed

Atahan, Ali O; Hiekmann, J Marten; Himpe, Jeffrey; Marra, Joseph

2018-07-01

Road restraint systems are designed to minimize the undesirable effects of roadside accidents and improve safety of road users. These systems are utilized at either side or median section of roads to contain and redirect errant vehicles. Although restraint systems are mainly designed against car, truck and bus impacts there is an increasing pressure by the motorcycle industry to incorporate motorcycle protection systems into these systems. In this paper development details of a new and versatile motorcycle barrier, CMPS, coupled with an existing vehicle barrier is presented. CMPS is intended to safely contain and redirect motorcyclists during a collision event. First, crash performance of CMPS design is evaluated by means of a three dimensional computer simulation program LS-DYNA. Then full-scale crash tests are used to verify the acceptability of CMPS design. Crash tests were performed at CSI proving ground facility using a motorcycle dummy in accordance with prEN 1317-8 specification. Full-scale crash test results show that CMPS is able to successfully contain and redirect dummy with minimal injury risk on the dummy. Damage on the barrier is also minimal proving the robustness of the CMPS design. Based on the test findings and further review by the authorities the implementation of CMPS was recommended at highway system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Endurance of rockfall protection fences

NASA Astrophysics Data System (ADS)

Gerber, W.; Meyer, M.

2009-04-01

Research on rockfall protection systems usually focuses on the performance of flexible barriers regarding their limit or design energy retention capacity. This research increased the maximum retention by a factor 15 within the last 15-20 years. Today rockfall energies up to 5'000 kJ can be retained. But this is relevant only for actual projects and newly erected barriers. However, the majority of all barriers installed in the alpine area were built many years ago and there is little knowledge on their long-term performance. Among others this includes not only the consideration of maintenance works such as man and machine power as well as yearly costs, but also the endurance of such barriers over the years. Such information normally stays at the authority or institution that initiated the construction of a protection system and/or is responsible for the maintenance of the object. But even if an institution maintains a large number of barriers, there mostly does not exist a general inventory because the barriers were installed over a time period of sometimes more than 30 years enduring many changes in the inventory procedures, drawings and documentations. Therefore, an actual investigation of all rockfall barriers protecting a sector of the Swiss railways (SBB) was performed in order to obtain an overview of their conditions. This project delivers both a detailed analysis of more than 100 single barriers and a statistically evaluable overview. It also allows a comparison between different generations of barrier types, independently from the different producers of the barriers. In a first step existing catalogues and data belonging to the relevant barriers were evaluated, summarized and mapped into topographic maps using GIS allowing a proper planning of the field trip, optimised regarding route, time consumption and possibly necessary closures of rail tracks. During the field investigations each barrier was inspected and all details regarding structural system, geometry, age, retained rockfall volume, probable remaining load capacity, damages, mistakes during erection, sufficient distance to rail tracks for the stopping process of the falling rock etc. were logged and photographically documented. The posterior analyses then lead to an overall classification of the single barriers into the three groups good/sufficent/insufficent resulting in different priority levels regarding the next suggested maintenance steps. The classification depends on whether a barrier can stop a frequent and a medium-sized rockfall event or not. The analysis gives a general overview of all barriers as well as a separate describtion of all criticised barriers to enable a proper planning of the repair tasks. The final summary over all barriers within the investigated sector can also be used to predict the expenditure on repairs for other areas assuming that the investigated barriers reflect the average of barriers installed in other areas. It also revealed that the barriers can be divided into two main groups older and younger than 1990. Around this date the rockfall retention techniques changed completely from more or less rigid fences towards full dynamically operating systems with net curtain effects along support ropes and special energy absorbing devices. For the first time, such an extensive inventory has been compiled and revealed its necessity to now have a unified data basis. The investigation also showed - and this will be shown more closely in the presentation - an in general good status of the protection systems after many years of operation. Although most of the modern flexible barriers are general in a good status, too, it has to be pointed out, that they are not necessarily appropriate to protect the railway infrastructure if they are erected to close to the tracks. The required stopping distance of the barriers has to be taken into account.

10 CFR 36.23 - Access control.

Code of Federal Regulations, 2010 CFR

2010-01-01

... REGULATORY COMMISSION LICENSES AND RADIATION SAFETY REQUIREMENTS FOR IRRADIATORS Design and Performance... irradiator must have a door or other physical barrier to prevent inadvertent entry of personnel if the sources are not in the shielded position. Product conveyor systems may serve as barriers as long as they...

CARBON-BASED REACTIVE BARRIER FOR NITRATE REMEDIATION AT A FORMER SWINE CAFO

EPA Science Inventory

Nitrate (NO3-) is a common ground water contaminant related to agricultural activity, waste water disposal, leachate from landfills, septic systems, and industrial processes. This study reports on the performance of a carbon-based permeable reactive barrier (PRB) that was constr...

Future Optical Communications Systems

DTIC Science & Technology

2008-06-01

rich handsets are driving growth in the wireless backhaul market. Both the iPhone and Blackberry are growing in popularity. Figure 49 forecasts the...electronic emission and tunneling , and hetero-barrier leakage. In barrier thermo-electronic emission, the conduction band of the quantum well laser is...barrier can reduce the mod- ulation bandwidth of the laser and reduce high-temperature performance due to tunneling out of the p-n junction or due

HgCdTe barrier infrared detectors

NASA Astrophysics Data System (ADS)

Kopytko, M.; Rogalski, A.

2016-05-01

In the last decade, new strategies to achieve high-operating temperature (HOT) detectors have been proposed, including barrier structures such as nBn devices, unipolar barrier photodiodes, and multistage (cascade) infrared detectors. The ability to tune the positions of the conduction and valence band edges independently in a broken-gap type-II superlattices is especially helpful in the design of unipolar barriers. This idea has been also implemented in HgCdTe ternary material system. However, the implementation of this detector structure in HgCdTe material system is not straightforward due to the existence of a valence band discontinuity (barrier) at the absorber-barrier interface. In this paper we present status of HgCdTe barrier detectors with emphasis on technological progress in fabrication of MOCVD-grown HgCdTe barrier detectors achieved recently at the Institute of Applied Physics, Military University of Technology. Their performance is comparable with state-of-the-art of HgCdTe photodiodes. From the perspective of device fabrication their important technological advantage results from less stringent surface passivation requirements and tolerance to threading dislocations.

Effects of yttrium, aluminum, and chromium concentrations in bond coatings on the performance of zirconia-yttria thermal barriers

NASA Technical Reports Server (NTRS)

Stecura, S.

1979-01-01

A cyclic furnace study was conducted between 990 - 280 C and 1095 - 280 C to evaluate the effects of yttrium, chromium, and aluminum concentrations in nickel base alloy bond coatings and also the effect of the bond coating thickness on the performance of yttria-stabilized zirconia thermal barrier coatings. The presence and the concentration of yttrium is very critical. Without yttrium, rapid oxidation of Ni-Al, Ni-Cr, and Ni-Cr-Al bond coatings causes zirconia thermal barrier coatings to fail very rapidly. Concentrations of chrominum and aluminum in Ni-Cr-Al-Y bond coating have a very significant effect on the thermal barrier coating life. This effect, however, is not as great as that due to yttrium. Furthermore, the thickness and the thickness uniformity also have a very significant effect on the life of the thermal barrier system.

An Evaluation of High Temperature Airframe Seals for Advanced Hypersonic Vehicles

NASA Technical Reports Server (NTRS)

DeMange, Jeffrey J.; Dunlap, Patrick H.; Steinetz, Bruce M.; Drlik, Gary J.

2007-01-01

High temperature seals are required for advanced hypersonic airframe applications. In this study, both spring tube thermal barriers and innovative wafer seal systems were evaluated under relevant hypersonic test conditions (temperatures, pressures, etc.) via high temperature compression testing and room temperature flow assessments. Thermal barriers composed of a Rene 41 spring tube filled with Saffil insulation and overbraided with a Nextel 312 sheath showed acceptable performance at 1500 F in both short term and longer term compression testing. Nextel 440 thermal barriers with Rene 41 spring tubes and Saffil insulation demonstrated good compression performance up to 1750 F. A silicon nitride wafer seal/compression spring system displayed excellent load performance at temperatures as high as 2200 F and exhibited room temperature leakage values that were only 1/3 those for the spring tube rope seals. For all seal candidates evaluated, no significant degradation in leakage resistance was noted after high temperature compression testing. In addition to these tests, a superalloy seal suitable for dynamic seal applications was optimized through finite element techniques.

California's digital divide: clinical information systems for the haves and have-nots.

PubMed

Miller, Robert H; D'Amato, Katherine; Oliva, Nancy; West, Christopher E; Adelson, Joel W

2009-01-01

Strong barriers prevent the financing of clinical information systems (CIS) in health care delivery system organizations in market segments serving disadvantaged patients. These segments include community health centers, public hospitals, unaffiliated rural hospitals, and some Medicaid-oriented solo and small-group medical practices. Policy interventions such as loans, grants, pay-for-performance and other reimbursement changes, and support services assistance will help lower these barriers. Without intervention, progress will be slow and worsen health care disparities between the advantaged and disadvantaged populations.

Combined Thermomechanical and Environmental Durability of Environmental Barrier Coating Systems on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna

2016-01-01

Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) will play a crucial role in next generation turbine engines for hot-section component applications. The development of prime-reliant environmental barrier coatings is essential to the EBC-CMC system durability, ensuring the successful implementations of the high temperature and lightweight engine component technologies for engine applications.This paper will emphasize recent NASA environmental barrier coating and CMC developments for SiC/SiC turbine airfoil components, utilizing advanced coating compositions and processing methods. The emphasis has been particularly placed on thermomechanical and environment durability evaluations of EBC-CMC systems. We have also addressed the integration of the EBCs with advanced SiC/SiC CMCs, and studied the effects of combustion environments and Calcium-Magnesium-Alumino-Silicate (CMAS) deposits on the durability of the EBC-CMC systems under thermal gradient and mechanical loading conditions. Advanced environmental barrier coating systems, including multicomponent rare earth silicate EBCs and HfO2-Si based bond coats, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

Workplace barriers encountered by employed persons with systemic sclerosis.

PubMed

Poole, Janet L; Anwar, Sahar; Mendelson, Cindy; Allaire, Saralynn

2016-01-01

Systemic sclerosis (SSc) is an auto-immune connective tissue disease characterized by fibrosis of skin, blood vessels, and internal organs that results in significant disability. To identify the work barriers faced by people with systemic sclerosis (SSc) in maintaining employment. Thirty-six people with SSc who were working more than 8 hours per week completed the Work Experience Survey, which contains lists of potential work barriers, including the ability to travel to and from work; get around at work; perform essential job functions, including physical, cognitive, and task-related activities; work with others; and manage work conditions. Thirty-three participants completed and returned the questionnaires, most of whom were female, and working full time and in professional careers. Principal disease symptoms included fatigue, Raynaud's phenomenon, esophageal involvement, and leg or hand/wrist pain. All participants reported some barriers with a mean of 18 barriers per participant. At least three quarters of participants cited outside temperature (82%), cold temperatures inside the workplace (76%), and household work (76%), as barriers. The next most common barriers were using both hands (64%), arranging and taking part in social activities (64%), being able to provide self-care (61%) and working 8 hours (58%). Participants reported a wide range of barriers, from cold temperatures, to physical job, fatigue related, and non-workplace demands, in maintaining the worker role. The barriers reflect the disease symptoms they reported. Identifying workplace barriers facilitates the creation of job accommodations or adaptations that will allow people with SSc to continue working.

Assessing barriers to adherence in routine clinical care for pediatric kidney transplant patients.

PubMed

Varnell, Charles D; Rich, Kristin L; Nichols, Melissa; Dahale, Devesh; Goebel, Jens W; Pai, Ahna L H; Hooper, David K; Modi, Avani C

2017-11-01

Patient-identified barriers to immunosuppressive medications are associated with poor adherence and negative clinical outcomes in transplant patients. Assessment of adherence barriers is not part of routine post-transplant care, and studies regarding implementing such a process in a reliable way are lacking. Using the Model for Improvement and PDSA cycles, we implemented a system to identify adherence barriers, including patient-centered design of a barriers assessment tool, identification of eligible patients, clear roles for clinic staff, and creating a culture of non-judgmental discussion around adherence. We performed time-series analysis of our process measure. Secondary analyses examined the endorsement and concordance of adherence barriers between patient-caregiver dyads. After three methods of testing, the most reliable delivery system was an EHR-integrated tablet that alerted staff of patient eligibility for assessment. Barriers were endorsed by 35% of caregivers (n=85) and 43% of patients (n=60). The most frequently patient-endorsed barriers were forgetting, poor taste, and side effects. Caregivers endorsed forgetting and side effects. Concordance between patient-caregiver dyads was fair (k=0.299). Standardized adherence barriers assessment is feasible in the clinical care of pediatric kidney transplant patients. Features necessary for success included automation, redundant systems with designated staff to identify and mitigate failures, aligned reporting structures, and reliable measurement approaches. Future studies will examine whether barriers predict clinical outcomes (eg, organ rejection, graft loss). © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Healthcare waste management: an interpretive structural modeling approach.

PubMed

Thakur, Vikas; Anbanandam, Ramesh

2016-06-13

Purpose - The World Health Organization identified infectious healthcare waste as a threat to the environment and human health. India's current medical waste management system has limitations, which lead to ineffective and inefficient waste handling practices. Hence, the purpose of this paper is to: first, identify the important barriers that hinder India's healthcare waste management (HCWM) systems; second, classify operational, tactical and strategical issues to discuss the managerial implications at different management levels; and third, define all barriers into four quadrants depending upon their driving and dependence power. Design/methodology/approach - India's HCWM system barriers were identified through the literature, field surveys and brainstorming sessions. Interrelationships among all the barriers were analyzed using interpretive structural modeling (ISM). Fuzzy-Matrice d'Impacts Croisés Multiplication Appliquée á un Classement (MICMAC) analysis was used to classify HCWM barriers into four groups. Findings - In total, 25 HCWM system barriers were identified and placed in 12 different ISM model hierarchy levels. Fuzzy-MICMAC analysis placed eight barriers in the second quadrant, five in third and 12 in fourth quadrant to define their relative ISM model importance. Research limitations/implications - The study's main limitation is that all the barriers were identified through a field survey and barnstorming sessions conducted only in Uttarakhand, Northern State, India. The problems in implementing HCWM practices may differ with the region, hence, the current study needs to be replicated in different Indian states to define the waste disposal strategies for hospitals. Practical implications - The model will help hospital managers and Pollution Control Boards, to plan their resources accordingly and make policies, targeting key performance areas. Originality/value - The study is the first attempt to identify India's HCWM system barriers and prioritize them.

Development and Performance Evaluations of HfO2-Si and Rare Earth-Si Based Environmental Barrier Bond Coat Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2014-01-01

Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si based EBC bond coat systems for SiCSiC CMC combustor and turbine airfoil applications are investigated. The coating design approach and stability requirements are specifically emphasized, with the development and implementation focusing on Plasma Sprayed (PS) and Electron Beam-Physic Vapor Deposited (EB-PVD) coating systems and the composition optimizations. High temperature properties of the HfO2-Si based bond coat systems, including the strength, fracture toughness, creep resistance, and oxidation resistance were evaluated in the temperature range of 1200 to 1500 C. Thermal gradient heat flux low cycle fatigue and furnace cyclic oxidation durability tests were also performed at temperatures up to 1500 C. The coating strength improvements, degradation and failure modes of the environmental barrier coating bond coat systems on SiCSiC CMCs tested in simulated stress-environment interactions are briefly discussed and supported by modeling. The performance enhancements of the HfO2-Si bond coat systems with rare earth element dopants and rare earth-silicon based bond coats are also highlighted. The advanced bond coat systems, when integrated with advanced EBC top coats, showed promise to achieve 1500 C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and long-term durability.

Environmental Stability and Oxidation Behavior of HfO2-Si and YbGd(O) Based Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Farmer, Serene; McCue, Terry R.; Harder, Bryan; Hurst, Janet B.

2017-01-01

Ceramic environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiCSiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, environmental durable environmental barrier coating systems. In this paper, the durability and performance of advanced Electron Beam-Physical Vapor Deposition (EB-PVD) NASA HfO2-Si and YbGdSi(O) EBC bond coat top coat systems for SiCSiC CMC have been summarized. The high temperature thermomechanical creep, fatigue and oxidation resistance have been investigated in the laboratory simulated high-heat-flux environmental test conditions. The advanced NASA EBC systems showed promise to achieve 1500C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and durability.

Restructuring Resources for High-Performing Schools: A Primer for State Policymakers

ERIC Educational Resources Information Center

Miles, Karen Hawley; Baroody, Karen

2011-01-01

There are very real barriers to using people, time, money, and technology well in today's public schools systems. To begin to break down these barriers, the Education Resource Strategies (ERS) has created a framework to prioritize seven urgent restructuring priorities. The authors have found that these areas represent the largest opportunities for…

Effect of joint mechanism on vehicle redirectional capability of water-filled road safety barrier systems.

PubMed

Thiyahuddin, M I; Thambiratnam, D P; Gu, Y T

2014-10-01

Portable water-filled barriers (PWFBs) are roadside appurtenances that prevent vehicles from penetrating into temporary construction zones on roadways. PWFBs are required to satisfy the strict regulations for vehicle re-direction in tests. However, many of the current PWFBs fail to re-direct the vehicle at high speeds due to the inability of the joints to provide appropriate stiffness. The joint mechanism hence plays a crucial role in the performance of a PWFB system at high speed impacts. This paper investigates the desired features of the joint mechanism in a PWFB system that can re-direct vehicles at high speeds, while limiting the lateral displacement to acceptable limits. A rectangular "wall" representative of a 30m long barrier system was modeled and a novel method of joining adjacent road barriers was introduced through appropriate pin-joint connections. The impact response of the barrier "wall" and the vehicle was obtained and the results show that a rotational stiffness of 3000kNm/rad at the joints seems to provide the desired features of the PWFB system to re-direct impacting vehicles and restrict the lateral deflection. These research findings will be useful to safety engineers and road barrier designers in developing a new generation of PWFBs for increased road safety. Copyright © 2014 Elsevier Ltd. All rights reserved.

Performance reporting for consumers: issues for the Australian private hospital sector.

PubMed

Sheahan, Margo; Little, Russ; Leggat, Sandra G

2007-05-30

A group of consumers of private hospital services and their carers collaborated with staff of a Melbourne private hospital and with industry representatives to develop a consumer-driven performance report on cardiac services. During the development process participating consumers identified situational and structural barriers to their right to be informed of costs, to choice and to quality care. Their growing appreciation of these barriers led them to a different perspective on performance reporting, which resulted in their redirecting the project. The consumer participants no longer wanted a performance report that provided comparative quantitative data. Instead they designed a report that outlined the structures, systems and processes the hospital had in place to address the quality and safety of services provided. In addition, consumer participants developed a decision support tool for consumers to use in navigating the private health care sector. The journey of these consumers in creating a consumer driven performance report for a private hospital service may assist those responsible for governance of Australia's health system in choosing appropriate strategies and mechanisms to enhance private hospital accountability. The situational and institutional industry barriers to choice, information and quality identified by these consumers need to be addressed before public performance reporting for private hospitals is introduced in Australia.

Performance reporting for consumers: issues for the Australian private hospital sector

PubMed Central

Sheahan, Margo; Little, Russ; Leggat, Sandra G

2007-01-01

A group of consumers of private hospital services and their carers collaborated with staff of a Melbourne private hospital and with industry representatives to develop a consumer-driven performance report on cardiac services. During the development process participating consumers identified situational and structural barriers to their right to be informed of costs, to choice and to quality care. Their growing appreciation of these barriers led them to a different perspective on performance reporting, which resulted in their redirecting the project. The consumer participants no longer wanted a performance report that provided comparative quantitative data. Instead they designed a report that outlined the structures, systems and processes the hospital had in place to address the quality and safety of services provided. In addition, consumer participants developed a decision support tool for consumers to use in navigating the private health care sector. The journey of these consumers in creating a consumer driven performance report for a private hospital service may assist those responsible for governance of Australia's health system in choosing appropriate strategies and mechanisms to enhance private hospital accountability. The situational and institutional industry barriers to choice, information and quality identified by these consumers need to be addressed before public performance reporting for private hospitals is introduced in Australia. PMID:17537238

Geothermal Academy: Focus Center for Data Collection, Analysis, and Dissemination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakagawa, Masami, Ph.D.; Fujiono, Hendro, Ph.D.; McCartney, John S., Ph.D.

2011-10-31

Geothermal Academy: A Pathway for Confirmation of Ground-Source Heat Pumps in the United States. In 2008, Oak Ridge National Laboratory issued a report on geothermal heats pumps (GHPs) focused on the market status, barriers to adoption, and actions to overcome these barriers (Hughes 2008). Of the barriers raised in this report, of the most pressing is the lack of performance and energy usage data for GHPs. Further, an associated barrier is a lack of a fair comparison of the energy usage of conventional heating and cooling systems for the same building. Because of these barriers, we are not able tomore » say how much energy is used by well-designed GHP systems on a long-term basis, nor are we able to say how better their energy usage is compared to conventional systems. The need for a fair comparison with conventional systems is particularly relevant as modern versions of conventional air conditioners, gas furnaces, and boilers have also incorporated energy saving technologies. As a first step to address this barrier, the Geothermal Academy has developed a framework for data collection. This framework has already been applied to several geothermal installations in Colorado (Nakagawa etal. 2010). The framework classifies data into different categories based on the relevance of the dat to understanding the energy consumption of a GHP system. The categories are: direct energy consumption data, heat exchange performance data, and GHP design parameter data. The main recommendation of this project is to include a minimal data collection system on each heat pump installed in the U.S., capable of measuring the electrical energy consumed, the entering/exiting fluid temperatures, and circulation rates. This is a viable and cost effective solution which will provide performance data, as data collection systems are only a fraction of the cost of a GHP unit and modern GHP units already incorporate sensors to monitor energy usage and the entering and exiting fluid temperatures. Specifically, these sensors are used to control the GHP unit to provide the heat exchange required to provide a desired temperature within a building. Accordingly, it is straightforward for this operational data to be collected to start building a database of GHP performance such that can provide statistically relevant comparison with other heating and cooling systems. In addition to collecting the data, such a system could be easily implemented with a wireless transmitter so that data could be sent to a home PC where it could be transmitted to a central database. Display of the data on a user's PC would provide feedback on the performance of their system which could perhaps refine their use of the system to reach their personal energy goals. Although a system such as that described above has yet to be incorporated directly into commercial GHP systems, it is straightforward and inexpensive to outfit a GHP with a data acquisition system and supplemental sensors. A secondary recommendation is to consider funding a pilot effort that will collect the energy and performance time series data from a representative sample of installations. A preliminary pilot effort was undertaken by the Geothermal Academy at a middle school in Ft. Collins, Colorado, which demonstrated the feasibility and ease of such an effort. A full-scale pilot effort would be most suited to evaluate the performance of GHP installations in different climate settings, preferably focusing on residential, commercial, and public buildings. If a full-scale pilot effort were to be undertaken, it is recommended to also identify large buildings which may incorporate a back-up conventional heating and cooling system in order to provide statistically relevant comparison data to assess the improvement in GHP energy usage over other heating and cooling technologies. Such a data collection system would provide several benefits to the different sectors of society (consumers, installers, policy makers, researchers, utility companies, government regulators) which are concerned with GHP technology and implementation.« less

Complex Cognitive Performance and Antihistamine Use

DTIC Science & Technology

1990-04-01

22 Antihistamine Use and Sedation ...........................................24 Antihistamine Use and Physiological Measures...Reactivity and Sedation in Healthy Volunteers after Administration of Hismanal, Alone or in Combination with Central Nervous System Depressants...cross the blood-brain barrier easily, resulting in central nervous system effects such as sedation , drowsiness, and altered psychomotor performance

Effect of thermal barrier coatings on the performance of steam and water-cooled gas turbine/steam turbine combined cycle system

NASA Technical Reports Server (NTRS)

Nainiger, J. J.

1978-01-01

An analytical study was made of the performance of air, steam, and water-cooled gas-turbine/steam turbine combined-cycle systems with and without thermal-barrier coatings. For steam cooling, thermal barrier coatings permit an increase in the turbine inlet temperature from 1205 C (2200 F), resulting in an efficiency improvement of 1.9 percentage points. The maximum specific power improvement with thermal barriers is 32.4 percent, when the turbine inlet temperature is increased from 1425 C (2600 F) to 1675 C (3050 F) and the airfoil temperature is kept the same. For water cooling, the maximum efficiency improvement is 2.2 percentage points at a turbine inlet temperature of 1683 C (3062 F) and the maximum specific power improvement is 36.6 percent by increasing the turbine inlet temperature from 1425 C (2600 F) to 1730 C (3150 F) and keeping the airfoil temperatures the same. These improvements are greater than that obtained with combined cycles using air cooling at a turbine inlet temperature of 1205 C (2200 F). The large temperature differences across the thermal barriers at these high temperatures, however, indicate that thermal stresses may present obstacles to the use of coatings at high turbine inlet temperatures.

Barrier distributions and signatures of transfer channels in the Ca40+Ni58,64 fusion reactions at energies around and below the Coulomb barrier

NASA Astrophysics Data System (ADS)

Bourgin, D.; Courtin, S.; Haas, F.; Stefanini, A. M.; Montagnoli, G.; Goasduff, A.; Montanari, D.; Corradi, L.; Fioretto, E.; Huiming, J.; Scarlassara, F.; Rowley, N.; Szilner, S.; Mijatović, T.

2014-10-01

Background: The nuclear structure of colliding nuclei is known to influence the fusion process. Couplings of the relative motion to nuclear shape deformations and vibrations lead to an enhancement of the sub-barrier fusion cross section in comparison with the predictions of one-dimensional barrier penetration models. This enhancement is explained by coupled-channels calculations including these couplings. The sub-barrier fusion cross section is also affected by nucleon transfer channels between the colliding nuclei. Purpose: The aim of the present experiment is to investigate the influence of the projectile and target nuclear structures on the fusion cross sections in the Ca40+Ni58 and Ca40+Ni64 systems. Methods: The experimental and theoretical fusion excitation functions as well as the barrier distributions were compared for these two systems. Coupled-channels calculations were performed using the ccfull code. Results: Good agreement was found between the measured and calculated fusion cross sections for the Ca40+Ni58 system. The situation is different for the Ca40+Ni64 system where the coupled-channels calculations with no nucleon transfer clearly underestimate the fusion cross sections below the Coulomb barrier. The fusion excitation function was, however, well reproduced at low and high energies by including the coupling to the neutron pair-transfer channel in the calculations. Conclusions: The nuclear structure of the colliding nuclei influences the fusion cross sections below the Coulomb barrier for both Ca40+Ni58,64 systems. Moreover, we highlighted the effect of the neutron pair-transfer channel on the fusion cross sections in Ca40+Ni64.

Evaluation of Oxidation Damage in Thermal Barrier Coating Systems

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.

1996-01-01

A method based on the technique of dilatometry has been established to quantitatively evaluate the interfacial damage due to the oxidation in a thermal barrier coating system. Strain isolation and adhesion coefficients have been proposed to characterize the thermal barrier coating (TBC) performance based on its thermal expansion behavior. It has been found that, for a thermal barrier coating system consisting of ZrO2-8%Y2O3/FeCrAlY/4140 steel substrate, the oxidation of the bond coat and substrate significantly reduced the ceramic coating adherence, as inferred from the dilatometry measurements. The in-situ thermal expansion measurements under 30 deg C to 700 deg C thermal cycling in air showed that the adhesion coefficient, A(sub i) decreased by 25% during the first 35 oxidation cycles. Metallography showed that delamination occurred at both the ceramic/bond coat and bond coat/substrate interfaces. In addition, the strain isolation effect has been improved by increasing the FeCrAlY bond coat thickness. The strain isolation coefficient, Si, increased from about 0.04 to 0.25, as the bond coat thickness changed from 0.1 mm to 1.0 mm. It may be possible to design optimum values of strain isolation and interface adhesion coefficients to achieve the best TBC performance.

Thermal and Environmental Barrier Coating Development for Advanced Propulsion Engine Systems

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Miller, Robert A.; Fox, Dennis S.

2008-01-01

Ceramic thermal and environmental barrier coatings (TEBCs) are used in gas turbine engines to protect engine hot-section components in the harsh combustion environments, and extend component lifetimes. Advanced TEBCs that have significantly lower thermal conductivity, better thermal stability and higher toughness than current coatings will be beneficial for future low emission and high performance propulsion engine systems. In this paper, ceramic coating design and testing considerations will be described for turbine engine high temperature and high-heat-flux applications. Thermal barrier coatings for metallic turbine airfoils and thermal/environmental barrier coatings for SiC/SiC ceramic matrix composite (CMC) components for future supersonic aircraft propulsion engines will be emphasized. Further coating capability and durability improvements for the engine hot-section component applications can be expected by utilizing advanced modeling and design tools.

A new physical barrier system for seawater intrusion control

NASA Astrophysics Data System (ADS)

Abdoulhalik, Antoifi; Ahmed, Ashraf; Hamill, G. A.

2017-06-01

The construction of subsurface physical barriers is one of various methods used to control seawater intrusion (SWI) in coastal aquifers. This study proposes the mixed physical barrier (MPB) as a new barrier system for seawater intrusion control, which combines an impermeable cutoff wall and a semi-permeable subsurface dam. The effect of the traditionally-used physical barriers on transient saltwater wedge dynamics was first explored for various hydraulic gradients, and the workability of the MPB was thereafter thoroughly analysed. A newly developed automated image analysis based on light-concentration conversion was used in the experiments, which were completed in a porous media tank. The numerical code SEAWAT was used to assess the consistency of the experimental data and examine the sensitivity of the performance of the barriers to various key parameters. The results show that the MPB induced a visible lifting of the dense saline flux upward towards the outlet by the light freshwater. This saltwater lifting mechanism, observed for the first time, induced significant reduction to the saline water intrusion length. The use of the MPB yielded up to 62% and 42% more reduction of the saltwater intrusion length than the semi-permeable dam and the cutoff wall, respectively. The performance achieved by the MPB with a wall depth of 40% of the aquifer thickness was greater than that of a single cutoff wall with a penetration depth of 90% of the aquifer thickness (about 13% extra reduction). This means that the MPB could produce better seawater intrusion reduction than the traditionally used barriers at even lower cost.

[On Atomic Nuclear Fusion Processes at Low-Temperatures. An Enhancement of the Probability of Transition through a Potential Barrier Due to the So-Called Barrier Anti-Zeno Effect].

PubMed

Namiot, V A

2016-01-01

It is known that in quantum mechanics the act of observing the experiment can affect the experimental findings in some cases. In particular, it happens under the so-called Zeno effect. In this work it is shown that in contrast to the "standard" Zeno-effect where the act of observing a process reduces the probability of its reality, an inverse situation when a particle transmits through a potential barrier (a so-called barrier anti-Zeno effect) can be observed, the observation of the particle essentially increases the probability of its transmission through the barrier. The possibility of using the barrier anti-Zeno effect is discussed to explain paradoxical results of experiments on "cold nuclear fusion" observed in various systems including biological ones. (According to the observers who performed the observations, the energy generation, which could not be explained by any chemical processes, as well as the change in the isotope and even element composition of the studied object may occur in these systems.

Investigating the influence on safety of retrofitting Italian motorways with barriers meeting a new EU standard.

PubMed

Cafiso, Salvatore; D'Agostino, Carmelo; Persaud, Bhagwant

2017-04-03

A new European Union (EU) regulation for safety barriers, which is based on performance, has encouraged road agencies to perform an upgrade of old barriers, with the expectation that there will be safety benefits at the retrofitted sites. The new class of barriers was designed and installed in compliance with the 1998 (European Norm) EN 1317 standards for road restraint systems, which lays down common requirements for the testing and certification of road restraint systems in all countries of the European Committee for Standardization (CEN). Both the older and new barriers are made of steel and are installed in such a way as to avoid vehicle intrusion, but the older ones are thought to be only effective at low speeds and large angles of impact. The new standard seeks to remedy this by providing better protection at higher speeds. This article seeks to quantify the effect on the frequency of fatal and injury crashes of retrofitting motorways with barriers meeting the new standards. The estimation of the crash modification was carried out by performing an empirical Bayes before-after analysis based on data from the A18 Messina-Catania motorway in Italy. The methodology has the great advantage to account for the regression to the mean effects. Besides, to account for time trend effects and dispersion of crash data, a modified calibration methodology of safety performance was used. This study, based on data collected on 76 km of motorway in the period 2000-2012, derived Crash Modification Factor point estimates that indicate reductions of 72% for run-off-road fatal and injury crashes and 38% in total fatal and injury crashes that could be expected by upgrading an old safety barrier by complying with new EU 1317 standards. The estimated benefit-cost ratio of 5.57 for total crashes indicates that the treatment is cost effective. The magnitude of this benefit indicates that the retrofits are cost-effective even for total crashes and should continue in any European country inasmuch as the estimated Crash Modification Factors are based on treatment sites that are reasonably representative of all European motorways.

EMS Provider Perceptions on Termination of Resuscitation in a Large, Urban EMS System.

PubMed

Tataris, Katie L; Richards, Christopher T; Stein-Spencer, Leslee; Ryan, Stephanie; Lazzara, Pete; Weber, Joseph M

2017-01-01

Despite the value of out-of-hospital Termination of Resuscitation (TOR) and the scientific evidence in favor of this practice, TOR has not been uniformly adopted or consistently practiced in EMS systems. Previous focus group studies have identified multiple barriers to implementation of out of hospital TOR but existing literature on EMS provider perceptions is limited. We sought to identify EMS providers' perceived barriers to performing out-of-hospital TOR in a large urban EMS system. The Chicago EMS System is a regional collaborative of EMS physicians, nurses and provider agencies, including the Chicago Fire Department (CFD), which provides exclusive emergency response for 9-1-1 calls in Chicago. CFD is an urban, fire-based EMS agency with a tiered response, with fire-fighter EMTs and paramedics providing initial care, and single role paramedics providing supplemental care and transport. A 2-page written survey was distributed to understand providers' experiences with managing OHCA and perceived barriers to TOR to inform subsequent improvements in protocol development and education. Of 3500 EMS providers that received the survey, 2309 were completed (66%). Survey respondent demographics were fire-fighter/EMTB (69%), fire-fighter/paramedic (14%), and single role paramedic (17%). The most frequent barrier to field TOR was scene safety (86%). The most common safety issue identified was family reaction to TOR (68%) and many providers felt threatened by family when trying to perform TOR (38%). Providers with a higher career numbers of OHCA were more likely to have felt threatened by the family (OR 6.70, 95% CI 2.99-15.00) and single role paramedics were more likely than FF/EMTBs to have felt threatened (OR 3.34, 95% CI 2.65-4.22). Barriers to delivering a death notification after TOR, include being uncomfortable or threatened with possible family reaction (52%) and family asking to continue the resuscitation (45%). There was lack of formal prior death notification training, the majority learned from colleagues through on the job training. Our study identifies scene safety, death notification delivery, and lack of formal training in death notification as barriers that EMS providers face while performing TOR in a large urban EMS system. These findings informed educational and operational initiatives to overcome the identified provider level issues and improve compliance with TOR policies.

Band structure effects on resonant tunneling in III-V quantum wells versus two-dimensional vertical heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campbell, Philip M., E-mail: philip.campbell@gatech.edu; Electronic Systems Laboratory, Georgia Tech Research Institute, Atlanta, Georgia 30332; Tarasov, Alexey

Since the invention of the Esaki diode, resonant tunneling devices have been of interest for applications including multi-valued logic and communication systems. These devices are characterized by the presence of negative differential resistance in the current-voltage characteristic, resulting from lateral momentum conservation during the tunneling process. While a large amount of research has focused on III-V material systems, such as the GaAs/AlGaAs system, for resonant tunneling devices, poor device performance and device-to-device variability have limited widespread adoption. Recently, the symmetric field-effect transistor (symFET) was proposed as a resonant tunneling device incorporating symmetric 2-D materials, such as transition metal dichalcogenides (TMDs),more » separated by an interlayer barrier, such as hexagonal boron-nitride. The achievable peak-to-valley ratio for TMD symFETs has been predicted to be higher than has been observed for III-V resonant tunneling devices. This work examines the effect that band structure differences between III-V devices and TMDs has on device performance. It is shown that tunneling between the quantized subbands in III-V devices increases the valley current and decreases device performance, while the interlayer barrier height has a negligible impact on performance for barrier heights greater than approximately 0.5 eV.« less

Shakeoff Ionization near the Coulomb Barrier Energy.

PubMed

Sharma, Prashant; Nandi, T

2017-11-17

We measure the projectile K x-ray spectra as a function of the beam energies around the Coulomb barrier in different collision systems. The energy is scanned in small steps around the barrier aiming to explore the nuclear effects on the elastically scattered projectile ions. The variation of the projectile x-ray energy with the ion-beam energies exhibits an unusual increase in between the interaction barrier and fusion barrier energies. This additional contribution to the projectile ionization can be attributed to the shakeoff of outer-shell electrons of the projectile ions due to the sudden nuclear recoil (∼10^{-21}  sec) caused by the attractive nuclear potential, which gets switched on near the interaction barrier energy. In the sudden approximation limit, the theoretical shakeoff probability calculation due to the nuclear recoil explains the observed data well. In addition to its fundamental interest, such processes can play a significant role in dark matter detection through the possible mechanism of x-ray emissions, where the weakly interacting massive particle-nucleus elastic scattering can lead to the nuclear-recoil-induced inner-shell vacancy creations. Furthermore, the present work may provide new prospects for atomic physics research at barrier energies as well as provide a novel technique to perform barrier distribution studies for two-body systems.

Shakeoff Ionization near the Coulomb Barrier Energy

NASA Astrophysics Data System (ADS)

Sharma, Prashant; Nandi, T.

2017-11-01

We measure the projectile K x-ray spectra as a function of the beam energies around the Coulomb barrier in different collision systems. The energy is scanned in small steps around the barrier aiming to explore the nuclear effects on the elastically scattered projectile ions. The variation of the projectile x-ray energy with the ion-beam energies exhibits an unusual increase in between the interaction barrier and fusion barrier energies. This additional contribution to the projectile ionization can be attributed to the shakeoff of outer-shell electrons of the projectile ions due to the sudden nuclear recoil (˜10-21 sec ) caused by the attractive nuclear potential, which gets switched on near the interaction barrier energy. In the sudden approximation limit, the theoretical shakeoff probability calculation due to the nuclear recoil explains the observed data well. In addition to its fundamental interest, such processes can play a significant role in dark matter detection through the possible mechanism of x-ray emissions, where the weakly interacting massive particle-nucleus elastic scattering can lead to the nuclear-recoil-induced inner-shell vacancy creations. Furthermore, the present work may provide new prospects for atomic physics research at barrier energies as well as provide a novel technique to perform barrier distribution studies for two-body systems.

Implementing a Lean Management System in Primary Care: Facilitators and Barriers From the Front Lines.

PubMed

Hung, Dorothy; Martinez, Meghan; Yakir, Maayan; Gray, Caroline

2015-01-01

Although Lean management techniques are increasingly used in health care to improve quality and reduce costs, lessons about how to successfully implement this approach on the front lines of care delivery are not well documented. In this study, we highlight key facilitators and barriers to implementing Lean among frontline primary care providers. This case study took place at a large, ambulatory care delivery system serving nearly 1 million patients. In-depth interviews were conducted with primary care physicians, staff, and administrators to identify key factors impacting Lean redesigns in primary care. Overall, staff engagement and performance management, sensitivity to the professional values and culture of medicine, and perceived adequacy of organizational resources were critical when introducing Lean changes. Specific drivers of change included empowerment of staff at all levels, visual display of performance metrics, and a culture of innovation and collaboration. Barriers included physician resistance to standardized work, difficulty transferring management responsibilities to non-physician staff, and time and staffing required for participating in improvement efforts. Although Lean offers a new approach to delivering care, the implementation process itself is both complex and crucial to success. Understanding early facilitators and barriers can maximize Lean's, potential to improve health care delivery.

Demonstration of close-coupled barriers for subsurface containment of buried waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dwyer, B.P.

1996-05-01

A close-coupled barrier is produced by first installing a conventional cement grout curtain followed by a thin inner lining of a polymer grout. The resultant barrier is a cement polymer composite that has economic benefits derived from the cement and performance benefits from the durable and resistant polymer layer. Close-coupled barrier technology is applicable for final, interim, or emergency containment of subsurface waste forms. Consequently, when considering the diversity of technology application, the construction emplacement and material technology maturity, general site operational requirements, and regulatory compliance incentives, the close-coupled barrier system provides an alternative for any hazardous or mixed wastemore » remediation plan. This paper discusses the installation of a close-coupled barrier and the subsequent integrity verification. The demonstration was installed at a benign site at the Hanford Geotechnical Test Facility, 400 Area, Hanford, Washington. The composite barrier was emplaced beneath a 7,500 liter tank. The tank was chosen to simulate a typical DOE Complex waste form. The stresses induced on the waste form were evaluated during barrier construction. The barrier was constructed using conventional jet grouting techniques. Drilling was completed at a 45{degree} angle to the ground, forming a conical shaped barrier with the waste form inside the cone. Two overlapping rows of cylindrical cement columns were grouted in a honeycomb fashion to form the secondary backdrop barrier layer. The primary barrier, a high molecular weight polymer manufactured by 3M Company, was then installed providing a relatively thin inner liner for the secondary barrier. The primary barrier was emplaced by panel jet grouting with a dual wall drill stem, two phase jet grouting system.« less

Development and Implementation of Sepsis Alert Systems.

PubMed

Harrison, Andrew M; Gajic, Ognjen; Pickering, Brian W; Herasevich, Vitaly

2016-06-01

Development and implementation of sepsis alert systems is challenging, particularly outside the monitored intensive care unit (ICU) setting. Barriers to wider use of sepsis alerts include evolving clinical definitions of sepsis, information overload, and alert fatigue, due to suboptimal alert performance. Outside the ICU, barriers include differences in health care delivery models, charting behaviors, and availability of electronic data. Current evidence does not support routine use of sepsis alert systems in clinical practice. Continuous improvement in the afferent and efferent aspects will help translate theoretic advantages into measurable patient benefit. Copyright © 2016 Elsevier Inc. All rights reserved.

The Cementitious Barriers Partnership (CBP) Software Toolbox Capabilities in Assessing the Degradation of Cementitious Barriers - 13487

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flach, G.P.; Burns, H.H.; Langton, C.

2013-07-01

The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the U.S. Department of Energy (US DOE) Office of Tank Waste and Nuclear Materials Management. The CBP program has developed a set of integrated tools (based on state-of-the-art models and leaching test methods) that help improve understanding and predictions of the long-term structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. Tools selected for and developed under this program have been used to evaluate and predict the behavior of cementitious barriers used in near-surface engineered waste disposal systems for periods of performance up tomore » 100 years and longer for operating facilities and longer than 1000 years for waste disposal. The CBP Software Toolbox has produced tangible benefits to the DOE Performance Assessment (PA) community. A review of prior DOE PAs has provided a list of potential opportunities for improving cementitious barrier performance predictions through the use of the CBP software tools. These opportunities include: 1) impact of atmospheric exposure to concrete and grout before closure, such as accelerated slag and Tc-99 oxidation, 2) prediction of changes in K{sub d}/mobility as a function of time that result from changing pH and redox conditions, 3) concrete degradation from rebar corrosion due to carbonation, 4) early age cracking from drying and/or thermal shrinkage and 5) degradation due to sulfate attack. The CBP has already had opportunity to provide near-term, tangible support to ongoing DOE-EM PAs such as the Savannah River Saltstone Disposal Facility (SDF) by providing a sulfate attack analysis that predicts the extent and damage that sulfate ingress will have on the concrete vaults over extended time (i.e., > 1000 years). This analysis is one of the many technical opportunities in cementitious barrier performance that can be addressed by the DOE-EM sponsored CBP software tools. Modification of the existing tools can provide many opportunities to bring defense in depth in prediction of the performance of cementitious barriers over time. (authors)« less

Two-well terahertz quantum cascade lasers with suppressed carrier leakage

DOE PAGES

Albo, Asaf; Flores, Yuri V.; Hu, Qing; ...

2017-09-11

The mechanisms that limit the temperature performance of diagonal GaAs/Al 0.15GaAs 0.85-based terahertz quantum cascade lasers (THz-QCLs) have been identified as thermally activated leakage of charge carriers through excited states into the continuum. THz-QCLs with energetically higher-laying excited states supported by sufficiently high barriers aim to eliminate these leakage mechanisms and lead to improved temperature performance. Although suppression of thermally activated carrier leakage was realized in a three-well THz-QCL based on a resonant-phonon scheme, no improvement in the temperature performance was reported thus far. Here, we report a major improvement in the temperature performance of a two-quantum-well direct-phonon THz-QCL structure.more » We show that the improved laser performance is due to the suppression of the thermally activated carrier leakage into the continuum with the increase in the injection barrier height. Furthermore, we demonstrate that high-barrier two-well structures can support a clean three-level laser system at elevated temperatures, which opens the opportunity to achieve temperature performance beyond the state-of-the-art.« less

Two-well terahertz quantum cascade lasers with suppressed carrier leakage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albo, Asaf; Flores, Yuri V.; Hu, Qing

The mechanisms that limit the temperature performance of diagonal GaAs/Al 0.15GaAs 0.85-based terahertz quantum cascade lasers (THz-QCLs) have been identified as thermally activated leakage of charge carriers through excited states into the continuum. THz-QCLs with energetically higher-laying excited states supported by sufficiently high barriers aim to eliminate these leakage mechanisms and lead to improved temperature performance. Although suppression of thermally activated carrier leakage was realized in a three-well THz-QCL based on a resonant-phonon scheme, no improvement in the temperature performance was reported thus far. Here, we report a major improvement in the temperature performance of a two-quantum-well direct-phonon THz-QCL structure.more » We show that the improved laser performance is due to the suppression of the thermally activated carrier leakage into the continuum with the increase in the injection barrier height. Furthermore, we demonstrate that high-barrier two-well structures can support a clean three-level laser system at elevated temperatures, which opens the opportunity to achieve temperature performance beyond the state-of-the-art.« less

Two-well terahertz quantum cascade lasers with suppressed carrier leakage

NASA Astrophysics Data System (ADS)

Albo, Asaf; Flores, Yuri V.; Hu, Qing; Reno, John L.

2017-09-01

The mechanisms that limit the temperature performance of diagonal GaAs/Al0.15GaAs0.85-based terahertz quantum cascade lasers (THz-QCLs) have been identified as thermally activated leakage of charge carriers through excited states into the continuum. THz-QCLs with energetically higher-laying excited states supported by sufficiently high barriers aim to eliminate these leakage mechanisms and lead to improved temperature performance. Although suppression of thermally activated carrier leakage was realized in a three-well THz-QCL based on a resonant-phonon scheme, no improvement in the temperature performance was reported thus far. Here, we report a major improvement in the temperature performance of a two-quantum-well direct-phonon THz-QCL structure. We show that the improved laser performance is due to the suppression of the thermally activated carrier leakage into the continuum with the increase in the injection barrier height. Moreover, we demonstrate that high-barrier two-well structures can support a clean three-level laser system at elevated temperatures, which opens the opportunity to achieve temperature performance beyond the state-of-the-art.

On the performance of capillary barriers as landfill cover

NASA Astrophysics Data System (ADS)

Kämpf, M.; Montenegro, H.

Landfills and waste heaps require an engineered surface cover upon closure. The capping system can vary from a simple soil cover to multiple layers of earth and geosynthetic materials. Conventional design features a compacted soil layer, which suffers from drying out and cracking, as well as root and animal intrusion. Capillary barriers consisting of inclined fine-over-coarse soil layers are investigated as an alternative cover system. Under unsaturated conditions, the textural contrast delays vertical drainage by capillary forces. The moisture that builds up above the contact will flow downdip along the interface of the layers. Theoretical studies of capillary barriers have identified the hydraulic properties of the layers, the inclination angle, the length of the field and the infiltration rate as the fundamental characteristics of the system. However, it is unclear how these findings can lead to design criteria for capillary barriers. To assess the uncertainty involved in such approaches, experiments have been carried out in a 8 m long flume and on large scale test sites (40 m x 15 m). In addition, the ability of a numerical model to represent the relevant flow processes in capillary barriers has been examined.

Barriers and facilitators to provide quality TIA care in the Veterans Healthcare Administration

PubMed Central

Miech, Edward J.; Sico, Jason J.; Phipps, Michael S.; Arling, Greg; Ferguson, Jared; Austin, Charles; Myers, Laura; Baye, Fitsum; Luckhurst, Cherie; Keating, Ava B.; Moran, Eileen; Bravata, Dawn M.

2017-01-01

Objective: To identify key barriers and facilitators to the delivery of guideline-based care of patients with TIA in the national Veterans Health Administration (VHA). Methods: We conducted a cross-sectional, observational study of 70 audiotaped interviews of multidisciplinary clinical staff involved in TIA care at 14 VHA hospitals. We de-identified and analyzed all transcribed interviews. We identified emergent themes and patterns of barriers to providing TIA care and of facilitators applied to overcome these barriers. Results: Identified barriers to providing timely acute and follow-up TIA care included difficulties accessing brain imaging, a constantly rotating pool of housestaff, lack of care coordination, resource constraints, and inadequate staff education. Key informants revealed that both stroke nurse coordinators and system-level factors facilitated the provision of TIA care. Few facilities had specific TIA protocols. However, stroke nurse coordinators often expanded upon their role to include TIA. They facilitated TIA care by (1) coordinating patient care across services, communicating across service lines, and educating clinical staff about facility policies and evidence-based practices; (2) tracking individual patients from emergency departments to inpatient settings and to discharge for timely follow-up care; (3) providing and referring TIA patients to risk factor management programs; and (4) performing regular audit and feedback of quality performance data. System-level facilitators included clinical service leadership engagement and use of electronic tools for continuous care across services. Conclusions: The local organization within a health care facility may be targeted to cultivate internal facilitators and a systemic infrastructure to provide evidence-based TIA care. PMID:29117959

Surface Conduction in III-V Semiconductor Infrared Detector Materials

NASA Astrophysics Data System (ADS)

Sidor, Daniel Evan

III-V semiconductors are increasingly used to produce high performance infrared photodetectors; however a significant challenge inherent to working with these materials is presented by unintended electrical conduction pathways that form along their surfaces. Resulting leakage currents contribute to system noise and are ineffectively mitigated by device cooling, and therefore limit ultimate performance. When the mechanism of surface conduction is understood, the unipolar barrier device architecture offers a potential solution. III-V bulk unipolar barrier detectors that effectively suppress surface leakage have approached the performance of the best II-VI pn-based structures. This thesis begins with a review of empirically determined Schottky barrier heights and uses this information to present a simple model of semiconductor surface conductivity. The model is validated through measurements of degenerate n-type surface conductivity on InAs pn junctions, and non-degenerate surface conductivity on GaSb pn junctions. It is then extended, along with design principles inspired by the InAs-based nBn detector, to create a flat-band pn-based unipolar barrier detector possessing a conductive surface but free of detrimental surface leakage current. Consideration is then given to the relative success of these and related bulk detectors in suppressing surface leakage when compared to analogous superlattice-based designs, and general limitations of unipolar barriers in suppressing surface leakage are proposed. Finally, refinements to the molecular beam epitaxy crystal growth techniques used to produce InAs-based unipolar barrier heterostructure devices are discussed. Improvements leading to III-V device performance well within an order of magnitude of the state-of-the-art are demonstrated.

CARRIER PREPARATION BUILDING MATERIALS HANDLING SYSTEM DESCRIPTION DOCUMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

E.F. Loros

2000-06-28

The Carrier Preparation Building Materials Handling System receives rail and truck shipping casks from the Carrier/Cask Transport System, and inspects and prepares the shipping casks for return to the Carrier/Cask Transport System. Carrier preparation operations for carriers/casks received at the surface repository include performing a radiation survey of the carrier and cask, removing/retracting the personnel barrier, measuring the cask temperature, removing/retracting the impact limiters, removing the cask tie-downs (if any), and installing the cask trunnions (if any). The shipping operations for carriers/casks leaving the surface repository include removing the cask trunnions (if any), installing the cask tie-downs (if any), installingmore » the impact limiters, performing a radiation survey of the cask, and installing the personnel barrier. There are four parallel carrier/cask preparation lines installed in the Carrier Preparation Building with two preparation bays in each line, each of which can accommodate carrier/cask shipping and receiving. The lines are operated concurrently to handle the waste shipping throughputs and to allow system maintenance operations. One remotely operated overhead bridge crane and one remotely operated manipulator is provided for each pair of carrier/cask preparation lines servicing four preparation bays. Remotely operated support equipment includes a manipulator and tooling and fixtures for removing and installing personnel barriers, impact limiters, cask trunnions, and cask tie-downs. Remote handling equipment is designed to facilitate maintenance, dose reduction, and replacement of interchangeable components where appropriate. Semi-automatic, manual, and backup control methods support normal, abnormal, and recovery operations. Laydown areas and equipment are included as required for transportation system components (e.g., personnel barriers and impact limiters), fixtures, and tooling to support abnormal and recovery operations. The Carrier Preparation Building Materials Handling System interfaces with the Cask/Carrier Transport System to move the carriers to and from the system. The Carrier Preparation Building System houses the equipment and provides the facility, utility, safety, communications, and auxiliary systems supporting operations and protecting personnel.« less

Evaluation of the Lifetime and Thermal Conductivity of Dysprosia-Stabilized Thermal Barrier Coating Systems

NASA Astrophysics Data System (ADS)

Curry, Nicholas; Markocsan, Nicolaie; Östergren, Lars; Li, Xin-Hai; Dorfman, Mitch

2013-08-01

The aim of this study was the further development of dysprosia-stabilized zirconia coatings for gas turbine applications. The target for these coatings was a longer lifetime and higher insulating performance compared to today's industrial standard thermal barrier coating. Two morphologies of ceramic top coat were studied: one using a dual-layer system and the second using a polymer to generate porosity. Evaluations were carried out using a laser flash technique to measure thermal properties. Lifetime testing was conducted using thermo-cyclic fatigue testing. Microstructure was assessed with SEM and Image analysis was used to characterize porosity content. The results show that coatings with an engineered microstructure give performance twice that of the present reference coating.

A pushing chronic care forward in Abu Dhabi by identifying priorities and addressing barriers: a modified Delphi technique

PubMed Central

Loney, Tom; Lapão, Luis V

2018-01-01

Objective This study aimed to elucidate the top five key priorities and barriers to chronic care in the health system of Abu Dhabi, United Arab Emirates (UAE). Design A modified Delphi study was performed to reach consensus on priority areas and barriers to the development of the Chronic Care Model in the health system of Abu Dhabi. Individual wireless audience response devices (keypads) linked to a computer were used to reduce 28 priorities and 20 barriers to the top five during three iterative rounds over three consecutive days. Setting Chronic care services for patients with diabetes, cardiovascular diseases and cancer, in both private and publicly funded healthcare services in the emirate of Abu Dhabi. Participants A purposive sample of 20 health systems’ experts were recruited. They were front-line healthcare workers from the public and private sector working in the delivery of care for patients with diabetes, cardiovascular diseases and cancer. Results The ‘overall organizational leadership in chronic illness care’ was ranked as the most important priority to address (26.3%) and ‘patient compliance’ was ranked as the most important barrier (36.8%) to the development of the Chronic Care Model. Conclusions This study has identified the current priorities and barriers to improving chronic care within Abu Dhabi’s healthcare system. Our paper addresses the UAE’s 2021 Agenda of achieving a world-class healthcare system, and findings may help inform strategic changes required to achieve this mission. PMID:29866724

Internal Medicine Hospitalists' Perceived Barriers and Recommendations for Optimizing Secondary Prevention of Osteoporotic Hip Fractures.

PubMed

Tan, Eng Keong; Loh, Kah Poh; Goff, Sarah L

2017-12-01

Osteoporosis is a major public health concern affecting an estimated 10 million people in the United States. To the best of our knowledge, no qualitative study has explored barriers perceived by medicine hospitalists to secondary prevention of osteoporotic hip fractures. We aimed to describe these perceived barriers and recommendations regarding how to optimize secondary prevention of osteoporotic hip fracture. In-depth, semistructured interviews were performed with 15 internal medicine hospitalists in a tertiary-care referral medical center. The interviews were analyzed with directed content analysis. Internal medicine hospitalists consider secondary osteoporotic hip fracture prevention as the responsibility of outpatient physicians. Identified barriers were stratified based on themes including physicians' perception, patients' characteristics, risks and benefits of osteoporosis treatment, healthcare delivery system, and patient care transition from the inpatient to the outpatient setting. Some of the recommendations include building an integrated system that involves a multidisciplinary team such as the fracture liaison service, initiating a change to the hospital policy to facilitate inpatient care and management of osteoporosis, and creating a smooth patient care transition to the outpatient setting. Our study highlighted how internal medicine hospitalists perceive their role in the secondary prevention of osteoporotic hip fractures and what they perceive as barriers to initiating preventive measures in the hospital. Inconsistency in patient care transition and the fragmented nature of the existing healthcare system were identified as major barriers. A fracture liaison service could remove some of these barriers.

Perceived barriers to the regionalization of adult critical care in the United States: a qualitative preliminary study

PubMed Central

Kahn, Jeremy M; Asch, Rebecca J; Iwashyna, Theodore J; Rubenfeld, Gordon D; Angus, Derek C; Asch, David A

2008-01-01

Background Regionalization of adult critical care services may improve outcomes for critically ill patients. We sought to develop a framework for understanding clinician attitudes toward regionalization and potential barriers to developing a tiered, regionalized system of care in the United States. Methods We performed a qualitative study using semi-structured interviews of critical care stakeholders in the United States, including physicians, nurses and hospital administrators. Stakeholders were identified from a stratified-random sample of United States general medical and surgical hospitals. Key barriers and potential solutions were identified by performing content analysis of the interview transcriptions. Results We interviewed 30 stakeholders from 24 different hospitals, representing a broad range of hospital locations and sizes. Key barriers to regionalization included personal and economic strain on families, loss of autonomy on the part of referring physicians and hospitals, loss of revenue on the part of referring physicians and hospitals, the potential to worsen outcomes at small hospitals by limiting services, and the potential to overwhelm large hospitals. Improving communication between destination and source hospitals, provider education, instituting voluntary objective criteria to become a designated referral center, and mechanisms to feed back patients and revenue to source hospitals were identified as potential solutions to some of these barriers. Conclusion Regionalization efforts will be met with significant conceptual and structural barriers. These data provide a foundation for future research and can be used to inform policy decisions regarding the design and implementation of a regionalized system of critical care. PMID:19014704

Advanced Environmental Barrier Coating and SA Tyrannohex SiC Composites Integration for Improved Thermomechanical and Environmental Durability

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Halbig, Michael; Singh, Mrityunjay

2018-01-01

The development of 2700 degF capable environmental barrier coating (EBC) systems, particularly, the Rare Earth "Hafnium" Silicon bond coat systems, have significantly improved the temperature capability and environmental stability of SiC/SiC Ceramic Matrix Composite Systems. We have specifically developed the advanced 2700 degF EBC systems, integrating the EBC to the high temperature SA Tyrannohex SiC fiber composites, for comprehensive performance and durability evaluations for potential turbine engine airfoil component applications. The fundamental mechanical properties, environmental stability and thermal gradient cyclic durability performance of the EBC - SA Tyrannohex composites were investigated. The paper will particularly emphasize the high pressure combustion rig recession, cyclic thermal stress resistance and thermomechanical low cycle fatigue testing of uncoated and environmental barrier coated Tyrannohex SiC SA composites in these simulated turbine engine combustion water vapor, thermal gradients, and mechanical loading conditions. We have also investigated high heat flux and flexural fatigue degradation mechanisms, determined the upper limits of operating temperature conditions for the coated SA composite material systems in thermomechanical fatigue conditions. Recent progress has also been made by using the self-healing rare earth-silicon based EBCs, thus enhancing the SA composite hexagonal fiber columns bonding for improved thermomechanical and environmental durability in turbine engine operation environments. More advanced EBC- composite systems based on the new EBC-Fiber Interphases will also be discussed.

Creep, Fatigue and Fracture Behavior of Environmental Barrier Coating and SiC-SiC Ceramic Matrix Composite Systems: The Role of Environment Effects

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Ghosn, Louis J.

2015-01-01

Advanced environmental barrier coating (EBC) systems for low emission SiCSiC CMC combustors and turbine airfoils have been developed to meet next generation engine emission and performance goals. This presentation will highlight the developments of NASAs current EBC system technologies for SiC-SiC ceramic matrix composite combustors and turbine airfoils, their performance evaluation and modeling progress towards improving the engine SiCSiC component temperature capability and long-term durability. Our emphasis has also been placed on the fundamental aspects of the EBC-CMC creep and fatigue behaviors, and their interactions with turbine engine oxidizing and moisture environments. The EBC-CMC environmental degradation and failure modes, under various simulated engine testing environments, in particular involving high heat flux, high pressure, high velocity combustion conditions, will be discussed aiming at quantifying the protective coating functions, performance and durability, and in conjunction with damage mechanics and fracture mechanics approaches.

NASA's Advanced Environmental Barrier Coatings Development for SiC/SiC Ceramic Matrix Composites: Understanding Calcium Magnesium Alumino-Silicate (CMAS) Degradations and Resistance

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2014-01-01

Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is essential to the viability and reliability of the envisioned CMC engine component applications, ensuring integrated EBC-CMC system durability and designs are achievable for successful applications of the game-changing component technologies and lifing methodologies.This paper will emphasize recent NASA environmental barrier coating developments for SiCSiC turbine airfoil components, utilizing advanced coating compositions, state-of-the-art processing methods, and combined mechanical and environment testing and durability evaluations. The coating-CMC degradations in the engine fatigue-creep and operating environments are particularly complex; one of the important coating development aspects is to better understand engine environmental interactions and coating life debits, and we have particularly addressed the effect of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the durability of the environmental barrier coating systems, and how the temperature capability, stability and cyclic life of the candidate rare earth oxide and silicate coating systems will be impacted in the presence of the CMAS at high temperatures and under simulated heat flux conditions. Advanced environmental barrier coating systems, including HfO2-Si with rare earth dopant based bond coat systems, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

Thermal Conductivity of Advanced Ceramic Thermal Barrier Coatings Determined by a Steady-state Laser Heat-flux Approach

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Miller, Robert A.

2004-01-01

The development of low conductivity and high temperature capable thermal barrier coatings requires advanced testing techniques that can accurately and effectively evaluate coating thermal conductivity under future high-performance and low-emission engine heat-flux conditions. In this paper, a unique steady-state CO2 laser (wavelength 10.6 microns) heat-flux approach is described for determining the thermal conductivity and conductivity deduced cyclic durability of ceramic thermal and environmental barrier coating systems at very high temperatures (up to 1700 C) under large thermal gradients. The thermal conductivity behavior of advanced thermal and environmental barrier coatings for metallic and Si-based ceramic matrix composite (CMC) component applications has also been investigated using the laser conductivity approach. The relationships between the lattice and radiation conductivities as a function of heat flux and thermal gradient at high temperatures have been examined for the ceramic coating systems. The steady-state laser heat-flux conductivity approach has been demonstrated as a viable means for the development and life prediction of advanced thermal barrier coatings for future turbine engine applications.

Predicting performance and performance satisfaction: mindfulness and beliefs about the ability to deal with social barriers in sport.

PubMed

Blecharz, Jan; Luszczynska, Aleksandra; Scholz, Urte; Schwarzer, Ralf; Siekanska, Malgorzata; Cieslak, Roman

2014-05-01

This research investigates the role of beliefs about the ability to deal with specific social barriers and its relationships to mindfulness, football performance, and satisfaction with one's own and team performance. Study 1 aimed at eliciting these social barriers. Study 2 tested (i) whether self-efficacy referring to social barriers would predict performance over and above task-related self-efficacy and collective efficacy and (ii) the mediating role of self-efficacy to overcome social barriers in the relationship between mindfulness and performance. Participants were football (soccer) players aged 16-21 years (Study 1: N=30; Study 2: N=101, longitudinal sample: n=88). Study 1 resulted in eliciting 82 social barriers referring to team, peer leadership, and coaches. Study 2 showed that task-related self-efficacy and collective efficacy explained performance satisfaction at seven-month follow-up, whereas self-efficacy referring to social barriers explained shooting performance at seven-month follow-up. Indirect associations between mindfulness and performance were found with three types of self-efficacy referring to social barriers, operating as parallel mediators. Results provide evidence for the role of beliefs about the ability to cope with social barriers and show a complex interplay between different types of self-efficacy and collective efficacy in predicting team sport performance.

How Can Medical Students Add Value? Identifying Roles, Barriers, and Strategies to Advance the Value of Undergraduate Medical Education to Patient Care and the Health System.

PubMed

Gonzalo, Jed D; Dekhtyar, Michael; Hawkins, Richard E; Wolpaw, Daniel R

2017-09-01

As health systems evolve, the education community is seeking to reimagine student roles that combine learning with meaningful contributions to patient care. The authors sought to identify potential stakeholders regarding the value of student work, and roles and tasks students could perform to add value to the health system, including key barriers and associated strategies to promote value-added roles in undergraduate medical education. In 2016, 32 U.S. medical schools in the American Medical Association's (AMA's) Accelerating Change in Education Consortium met for a two-day national meeting to explore value-added medical education; 121 educators, systems leaders, clinical mentors, AMA staff leadership and advisory board members, and medical students were included. A thematic qualitative analysis of workshop discussions and written responses was performed, which extracted key themes. In current clinical roles, students can enhance value by performing detailed patient histories to identify social determinants of health and care barriers, providing evidence-based medicine contributions at the point-of-care, and undertaking health system research projects. Novel value-added roles include students serving as patient navigators/health coaches, care transition facilitators, population health managers, and quality improvement team extenders. Six priority areas for advancing value-added roles are student engagement, skills, and assessments; balance of service versus learning; resources, logistics, and supervision; productivity/billing pressures; current health systems design and culture; and faculty factors. These findings provide a starting point for collaborative work to positively impact clinical care and medical education through the enhanced integration of value-added medical student roles into care delivery systems.

Systematics of capture and fusion dynamics in heavy-ion collisions

NASA Astrophysics Data System (ADS)

Wang, Bing; Wen, Kai; Zhao, Wei-Juan; Zhao, En-Guang; Zhou, Shan-Gui

2017-03-01

We perform a systematic study of capture excitation functions by using an empirical coupled-channel (ECC) model. In this model, a barrier distribution is used to take effectively into account the effects of couplings between the relative motion and intrinsic degrees of freedom. The shape of the barrier distribution is of an asymmetric Gaussian form. The effect of neutron transfer channels is also included in the barrier distribution. Based on the interaction potential between the projectile and the target, empirical formulas are proposed to determine the parameters of the barrier distribution. Theoretical estimates for barrier distributions and calculated capture cross sections together with experimental cross sections of 220 reaction systems with 182 ⩽ZPZT ⩽ 1640 are tabulated. The results show that the ECC model together with the empirical formulas for parameters of the barrier distribution work quite well in the energy region around the Coulomb barrier. This ECC model can provide prediction of capture cross sections for the synthesis of superheavy nuclei as well as valuable information on capture and fusion dynamics.

[Analysis on barriers of urban sustainable development based on DEMATEL: a case of Shenyang City].

PubMed

Li, Chun-Rong; Geng, Yong; Xue, Bing; Ren, Wan-Xia; Dong, Hui-Juan

2012-10-01

To scientifically identify the key barriers which the urban sustainable development is facing and to analyze the interrelationships among the barriers are of significance to promote urban sustainable development. Through literature review, site investigation and structural interview, 21 factors affecting the Shenyang City's sustainable development were recognized, and based on questionnaire survey and statistics analysis, 12 main factors were screened. Further, by employing decision-making and trial evaluation laboratory (DEMATEL) method, the interrelationships among these factors were analyzed. The key factors affecting the Shenyang's sustainable development included the lack of leaders' attention, the economy-oriented governmental performance evaluation system, the lower public awareness on sustainable development, and the lack of academic understanding on regional eco-carrying capacity and related key projects. It was suggested that the local government should pay more attention on sustainable development, increase propaganda activities, reform governmental performance evaluation system, establish a reward-punishment system for promoting sustainable development and an effective monitoring mechanism, and enhance the implementation of related regulations, the local enterprises should establish research and development funds to support the researches of key technologies and introduce key projects, and general publics should improve their awareness on sustainable development and actively participate in related activities.

Development and implementation of sepsis alert systems

PubMed Central

Harrison, Andrew M.; Gajic, Ognjen; Pickering, Brian W.; Herasevich, Vitaly

2016-01-01

Synopsis/Summary Development and implementation of sepsis alert systems is challenging, particularly outside the monitored intensive care unit (ICU) setting. Important barriers to wider use of sepsis alerts include evolving clinical definitions of sepsis, information overload & alert fatigue, due to suboptimal alert performance. Outside the ICU, additional barriers include differences in health care delivery models, charting behaviors, and availability of electronic data. Currently available evidence does not support routine use of sepsis alert systems in clinical practice. However, continuous improvement in both the afferent (data availability and accuracy of detection algorithms) and efferent (evidence-based decision support and smoother integration into clinical workflow) limbs of sepsis alert systems will help translate theoretical advantages into measurable patient benefit. PMID:27229639

Enhanced bioremediation of BTEX using immobilized nutrients: Field demonstration and monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borden, R.C.; Goin, R.T.; Kao, C.M.

1996-12-01

A permeable barrier system was developed for controlling the migration of dissolved contaminant plumes in ground water. The barrier system consisted of a line of closely spaced wells installed perpendicular to the contaminant plume. Each well contained concrete briquets that released oxygen and nitrate at a controlled rate, enhancing the aerobic biodegradation of dissolved hydrocarbons in the downgradient aquifer. A full scale permeable barrier system was constructed at a gasoline-spill site near Leland, NC. Initially, increased dissolved oxygen and decreased benzene, toluene, ethylbenzene, and xylene isomer (BTEX) concentrations in the downgradient aquifer indicated that oxygen released from the remediation wellsmore » was enhancing biodegradation. Field tracer tests and soil analyses performed at the conclusion of the project indicated that the aquifer in the vicinity of the remediation wells was being clogged by precipitation from iron minerals.« less

"Where to find those doctors?" A qualitative study on barriers and facilitators in access to and utilization of health care services by Polish migrants in Norway.

PubMed

Czapka, Elżbieta Anna; Sagbakken, Mette

2016-09-01

Poles constitute the largest group of migrants in Norway. Research confirms a steady inflow and a minimal outflow of Polish migrants. One of the key aspects of migrants' structural integration is access to health care services. This study explored barriers to and facilitators of Polish migrants' access to Norwegian health care services. A qualitative interview-based study was carried out between November 2013 and July 2014. The study is part of a larger, ongoing mixed-method study of Polish migrants' access to health care services in Norway. Semi-structured interviews were conducted with 19 Polish migrants in Oslo. The interviews were transcribed, coded, and analyzed. Thematic analysis was performed to identify barriers and facilitators related to the use of Norwegian health care services. Migrants experienced several barriers to and facilitators of access to health care services in Norway. The barriers most often mentioned were problems resulting from insufficient command of the language, related communication problems, and lack of knowledge about navigating the Norwegian health care system. Other barriers related to the organization of the health care system, perceptions of doctors' skills and practices, and attitudes among health personnel. Factors such as having a Polish social network, meeting friendly health personnel, and perceptions of equal treatment of all patients, facilitated access to and use of health care services. The study shows that there are both system- and patient-related barriers to and facilitators of migrants' access to health services in Norway. These findings suggest that successful inclusion of migrants into the Norwegian health system requires regular evaluation of access and utilization of health care services.

Defining Human Failure Events for Petroleum Risk Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ronald L. Boring; Knut Øien

2014-06-01

In this paper, an identification and description of barriers and human failure events (HFEs) for human reliability analysis (HRA) is performed. The barriers, called target systems, are identified from risk significant accident scenarios represented as defined situations of hazard and accident (DSHAs). This report serves as the foundation for further work to develop petroleum HFEs compatible with the SPAR-H method and intended for reuse in future HRAs.

Review of potential subsurface permeable barrier emplacement and monitoring technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riggsbee, W.H.; Treat, R.L.; Stansfield, H.J.

1994-02-01

This report focuses on subsurface permeable barrier technologies potentially applicable to existing waste disposal sites. This report describes candidate subsurface permeable barriers, methods for emplacing these barriers, and methods used to monitor the barrier performance. Two types of subsurface barrier systems are described: those that apply to contamination.in the unsaturated zone, and those that apply to groundwater and to mobile contamination near the groundwater table. These barriers may be emplaced either horizontally or vertically depending on waste and site characteristics. Materials for creating permeable subsurface barriers are emplaced using one of three basic methods: injection, in situ mechanical mixing, ormore » excavation-insertion. Injection is the emplacement of dissolved reagents or colloidal suspensions into the soil at elevated pressures. In situ mechanical mixing is the physical blending of the soil and the barrier material underground. Excavation-insertion is the removal of a soil volume and adding barrier materials to the space created. Major vertical barrier emplacement technologies include trenching-backfilling; slurry trenching; and vertical drilling and injection, including boring (earth augering), cable tool drilling, rotary drilling, sonic drilling, jetting methods, injection-mixing in drilled holes, and deep soil mixing. Major horizontal barrier emplacement technologies include horizontal drilling, microtunneling, compaction boring, horizontal emplacement, longwall mining, hydraulic fracturing, and jetting methods.« less

Control of Internal Transport Barriers in Magnetically Confined Fusion Plasmas

NASA Astrophysics Data System (ADS)

Panta, Soma; Newman, David; Sanchez, Raul; Terry, Paul

2016-10-01

In magnetic confinement fusion devices the best performance often involves some sort of transport barriers to reduce the energy and particle flow from core to edge. Those barriers create gradients in the temperature and density profiles. If gradients in the profiles are too steep that can lead to instabilities and the system collapses. Control of these barriers is therefore an important challenge for fusion devices (burning plasmas). In this work we focus on the dynamics of internal transport barriers. Using a simple 7 field transport model, extensively used for barrier dynamics and control studies, we explore the use of RF heating to control the local gradients and therefore the growth rates and shearing rates for barrier initiation and control in self-heated fusion plasmas. Ion channel barriers can be formed in self-heated plasmas with some NBI heating but electron channel barriers are very sensitive. They can be formed in self-heated plasmas with additional auxiliary heating i.e. NBI and radio-frequency(RF). Using RF heating on both electrons and ions at proper locations, electron channel barriers along with ion channel barriers can be formed and removed demonstrating a control technique. Investigating the role of pellet injection in controlling the barriers is our next goal. Work supported by DOE Grant DE-FG02-04ER54741.

Barriers and facilitators to provide quality TIA care in the Veterans Healthcare Administration.

PubMed

Damush, Teresa M; Miech, Edward J; Sico, Jason J; Phipps, Michael S; Arling, Greg; Ferguson, Jared; Austin, Charles; Myers, Laura; Baye, Fitsum; Luckhurst, Cherie; Keating, Ava B; Moran, Eileen; Bravata, Dawn M

2017-12-12

To identify key barriers and facilitators to the delivery of guideline-based care of patients with TIA in the national Veterans Health Administration (VHA). We conducted a cross-sectional, observational study of 70 audiotaped interviews of multidisciplinary clinical staff involved in TIA care at 14 VHA hospitals. We de-identified and analyzed all transcribed interviews. We identified emergent themes and patterns of barriers to providing TIA care and of facilitators applied to overcome these barriers. Identified barriers to providing timely acute and follow-up TIA care included difficulties accessing brain imaging, a constantly rotating pool of housestaff, lack of care coordination, resource constraints, and inadequate staff education. Key informants revealed that both stroke nurse coordinators and system-level factors facilitated the provision of TIA care. Few facilities had specific TIA protocols. However, stroke nurse coordinators often expanded upon their role to include TIA. They facilitated TIA care by (1) coordinating patient care across services, communicating across service lines, and educating clinical staff about facility policies and evidence-based practices; (2) tracking individual patients from emergency departments to inpatient settings and to discharge for timely follow-up care; (3) providing and referring TIA patients to risk factor management programs; and (4) performing regular audit and feedback of quality performance data. System-level facilitators included clinical service leadership engagement and use of electronic tools for continuous care across services. The local organization within a health care facility may be targeted to cultivate internal facilitators and a systemic infrastructure to provide evidence-based TIA care. Copyright © 2017 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.

Implementing clinical governance in English primary care groups/trusts: reconciling quality improvement and quality assurance.

PubMed

Campbell, S M; Sheaff, R; Sibbald, B; Marshall, M N; Pickard, S; Gask, L; Halliwell, S; Rogers, A; Roland, M O

2002-03-01

To investigate the concept of clinical governance being advocated by primary care groups/trusts (PCG/Ts), approaches being used to implement clinical governance, and potential barriers to its successful implementation in primary care. Qualitative case studies using semi-structured interviews and documentation review. Twelve purposively sampled PCG/Ts in England. Fifty senior staff including chief executives, clinical governance leads, mental health leads, and lay board members. Participants' perceptions of the role of clinical governance in PCG/Ts. PCG/Ts recognise that the successful implementation of clinical governance in general practice will require cultural as well as organisational changes, and the support of practices. They are focusing their energies on supporting practices and getting them involved in quality improvement activities. These activities include, but move beyond, conventional approaches to quality assessment (audit, incentives) to incorporate approaches which emphasise corporate and shared learning. PCG/Ts are also engaged in setting up systems for monitoring quality and for dealing with poor performance. Barriers include structural barriers (weak contractual levers to influence general practices), resource barriers (perceived lack of staff or money), and cultural barriers (suspicion by practice staff or problems overcoming the perceived blame culture associated with quality assessment). PCG/Ts are focusing on setting up systems for implementing clinical governance which seek to emphasise developmental and supportive approaches which will engage health professionals. Progress is intentionally incremental but formidable challenges lie ahead, not least reconciling the dual role of supporting practices while monitoring (and dealing with poor) performance.

GUIDANCE DOCUMENT ON IMPLEMENTATION OF THE ...

EPA Pesticide Factsheets

The Agreement in Principle for the Stage 2 M-DBP Federal Advisory Committee contains a list of treatment processes and management practices for water systems to use in meeting additional Cryptosporidium treatment requirements under the LT2ESWTR. This list, termed the microbial toolbox, includes watershed control programs, alternative intake locations, pretreatment processes, additional filtration barriers, inactivation technologies, and enhanced plant performance. The intent of the microbial toolbox is to provide water systems with broad flexibility in selecting cost-effective LT2ESWTR compliance strategies. Moreover, the toolbox allows systems that currently provide additional pathogen barriers or that can demonstrate enhanced performance to receive additional Cryptosporidium treatment credit. Provide guidance to utilities with surface water supplies and to state drinking water programs on the use of different treatment technologies to reduce the level of Cryptosporidium in drinking water. Technologies included in the guidance manual may be used to achieve compliance with the requirements of the LT2ESWTR.

Barriers to implementing infection prevention and control guidelines during crises: experiences of health care professionals.

PubMed

Timen, Aura; Hulscher, Marlies E J L; Rust, Laura; van Steenbergen, Jim E; Akkermans, Reinier P; Grol, Richard P T M; van der Meer, Jos W M

2010-11-01

Communicable disease crises can endanger the health care system and often require special guidelines. Understanding reasons for nonadherence to crisis guidelines is needed to improve crisis management. We identified and measured barriers and conditions for optimal adherence as perceived by 4 categories of health care professionals. In-depth interviews were performed (n = 26) to develop a questionnaire for a cross-sectional survey of microbiologists (100% response), infection preventionists (74% response), public health physicians (96% response), and public health nurses (82% response). The groups were asked to appraise barriers encountered during 4 outbreaks (severe acute respiratory syndrome [SARS], Clostridium difficile ribotype 027, rubella, and avian influenza) according to a 5-point Likert scale. When at least 33% of the participants responded "strongly agree," "agree," or "rather agree than disagree," a barrier was defined as "often experienced." The common ("generic") barriers were included in a univariate and multivariate model. Barriers specific to the various groups were studied as well. Crisis guidelines were found to have 4 generic barriers to adherence: (1) lack of imperative or precise wording, (2) lack of easily identifiable instructions specific to each profession, (3) lack of concrete performance targets, and (4) lack of timely and adequate guidance on personal protective equipment and other safety measures. The cross-sectional study also yielded profession-specific sets of often-experienced barriers. To improve adherence to crisis guidelines, the generic barriers should be addressed when developing guidelines, irrespective of the infectious agent. Profession-specific barriers require profession-specific strategies to change attitudes, ensure organizational facilities, and provide an adequate setting for crisis management. Copyright © 2010 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Clinical Saccharomyces cerevisiae isolates cannot cross the epithelial barrier in vitro.

PubMed

Pérez-Torrado, Roberto; Llopis, Silvia; Jespersen, Lene; Fernández-Espinar, Teresa; Querol, Amparo

2012-06-15

Saccharomyces cerevisiae is generally considered to be a safe organism and is essential to produce many different kinds of foods as well as being widely used as a dietary supplement. However, several isolates, which are genetically related to brewing and baking yeasts, have shown virulent traits, being able to produce human infections in immunodeficient patients. Previously it has been shown that the administration of S. cerevisiae clinical isolates can lead to systemic infections, reaching several organs in murine systems. In this work, we studied S. cerevisiae clinical isolates in an in vitro intestinal epithelial barrier model, comparing their behaviour with that of several strains of the related pathogens Candida glabrata and Candida albicans. The results showed that, in contrast to C. glabrata and C. albicans, S. cerevisiae was not able to cross the intestinal barrier. We concluded that S. cerevisiae can only perform opportunistic or passive crossings when epithelial barrier integrity is previously compromised. Copyright © 2012 Elsevier B.V. All rights reserved.

Remediation of groundwater contaminated with the lead-phenol binary system by granular dead anaerobic sludge-permeable reactive barrier.

PubMed

Faisal, Ayad A H; Abd Ali, Ziad T

2017-10-01

Computer solutions (COMSOL) Multiphysics 3.5a software was used for simulating the one-dimensional equilibrium transport of the lead-phenol binary system including the sorption process through saturated sandy soil as the aquifer and granular dead anaerobic sludge (GDAS) as the permeable reactive barrier. Fourier-transform infrared spectroscopy analysis proved that the carboxylic and alcohol groups are responsible for the bio-sorption of lead onto GDAS, while phosphines, aromatic and alkane are the functional groups responsible for the bio-sorption of phenol. Batch tests have been performed to characterize the equilibrium sorption properties of the GDAS and sandy soil in lead and/or phenol containing aqueous solutions. Numerical and experimental results proved that the barrier plays a potential role in the restriction of the contaminant plume migration and there is a linear relationship between longevity and thickness of the barrier. A good agreement between these results was recognized with root mean squared error not exceeding 0.04.

FY2016 Propulsion Materials Annual Progress Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

The Propulsion Materials Program actively supports the energy security and reduction of greenhouse emissions goals of VTO by investigating and identifying the materials properties that are most essential for continued development of cost-effective, highly efficient, and environmentally friendly next-generation heavy and light-duty powertrains. The technical approaches available to enhance propulsion systems focus on improvements in both vehicle efficiency and fuel substitution, both of which must overcome the performance limitations of the materials currently in use. Propulsion Materials Program activities work with national laboratories, industry experts, and VTO powertrain systems (e.g., Advanced Combustion Engines and Fuels) teams to develop strategies thatmore » overcome materials limitations in future powertrain performance. The technical maturity of the portfolio of funded projects ranges from basic science to subsystem prototype validation. Projects within a Propulsion Materials Program activity address materials concerns that directly impact critical technology barriers within each of the above programs, including barriers that impact fuel efficiency, thermal management, emissions reduction, improved reliability, and reduced manufacturing costs. The program engages only the barriers that result from material property limitations and represent fundamental, high-risk materials issues.« less

Comparing barrier algorithms

NASA Technical Reports Server (NTRS)

Arenstorf, Norbert S.; Jordan, Harry F.

1987-01-01

A barrier is a method for synchronizing a large number of concurrent computer processes. After considering some basic synchronization mechanisms, a collection of barrier algorithms with either linear or logarithmic depth are presented. A graphical model is described that profiles the execution of the barriers and other parallel programming constructs. This model shows how the interaction between the barrier algorithms and the work that they synchronize can impact their performance. One result is that logarithmic tree structured barriers show good performance when synchronizing fixed length work, while linear self-scheduled barriers show better performance when synchronizing fixed length work with an imbedded critical section. The linear barriers are better able to exploit the process skew associated with critical sections. Timing experiments, performed on an eighteen processor Flex/32 shared memory multiprocessor, that support these conclusions are detailed.

Altered Blood-Brain Barrier Permeability in Patients With Systemic Lupus Erythematosus: A Novel Imaging Approach.

PubMed

Gulati, Gaurav; Jones, Jordan T; Lee, Gregory; Altaye, Mekibib; Beebe, Dean W; Meyers-Eaton, Jamie; Wiley, Kasha; Brunner, Hermine I; DiFrancesco, Mark W

2017-02-01

To evaluate a safe, noninvasive magnetic resonance imaging (MRI) method to measure regional blood-brain barrier integrity and investigate its relationship with neurocognitive function and regional gray matter volume in juvenile-onset systemic lupus erythematosus (SLE). In this cross-sectional, case-control study, capillary permeability was measured as a marker of blood-brain barrier integrity in juvenile SLE patients and matched healthy controls, using a combination of arterial spin labeling and diffusion-weighted brain MRI. Regional gray matter volume was measured by voxel-based morphometry. Correlation analysis was done to investigate the relationship between regional capillary permeability and regional gray matter volume. Formal neurocognitive testing was completed (measuring attention, visuoconstructional ability, working memory, and psychomotor speed), and scores were regressed against regional blood-brain barrier integrity among juvenile SLE patients. Formal cognitive testing confirmed normal cognitive ability in all juvenile SLE subjects (n = 11) included in the analysis. Regional capillary permeability was negatively associated (P = 0.026) with neurocognitive performance concerning psychomotor speed in the juvenile SLE cohort. Compared with controls (n = 11), juvenile SLE patients had significantly greater capillary permeability involving Brodmann's areas 19, 28, 36, and 37 and caudate structures (P < 0.05 for all). There is imaging evidence of increased regional capillary permeability in juvenile SLE patients with normal cognitive performance using a novel noninvasive MRI technique. These blood-brain barrier outcomes appear consistent with functional neuronal network alterations and gray matter volume loss previously observed in juvenile SLE patients with overt neurocognitive deficits, supporting the notion that blood-brain barrier integrity loss precedes the loss of cognitive ability in juvenile SLE. Longitudinal studies are needed to confirm the findings of this pilot study. © 2016, American College of Rheumatology.

Exploring the Factors of an Enterprise Resource Planning System in a Local Government Organization

ERIC Educational Resources Information Center

Shaw, Bryan T.

2012-01-01

The enterprise resource planning (ERP) system industry accounts for $8.8 billion annually. Enterprise resource planning systems are not performing as expected due to implementation barriers, changes in job responsibilities, and access to information; 50% of all information technology failures are due to the implementation of ERP systems. Guided by…

Structural Conditions for Collaboration and Learning in Innovation Networks: Using an Innovation System Performance Lens to Analyse Agricultural Knowledge Systems

ERIC Educational Resources Information Center

Hermans, Frans; Klerkx, Laurens; Roep, Dirk

2015-01-01

Purpose: We investigate how the structural conditions of eight different European agricultural innovation systems can facilitate or hinder collaboration and social learning in multidisciplinary innovation networks. Methodology: We have adapted the Innovation System Failure Matrix to investigate the main barriers and enablers eight countries…

Early Detection of Junctional Adhesion Molecule-1 (JAM-1) in the Circulation after Experimental and Clinical Polytrauma

PubMed Central

Denk, Stephanie; Wiegner, Rebecca; Hönes, Felix M.; Messerer, David A. C.; Radermacher, Peter; Kalbitz, Miriam; Braumüller, Sonja; McCook, Oscar; Gebhard, Florian; Weckbach, Sebastian; Huber-Lang, Markus

2015-01-01

Severe tissue trauma-induced systemic inflammation is often accompanied by evident or occult blood-organ barrier dysfunctions, frequently leading to multiple organ dysfunction. However, it is unknown whether specific barrier molecules are shed into the circulation early after trauma as potential indicators of an initial barrier dysfunction. The release of the barrier molecule junctional adhesion molecule-1 (JAM-1) was investigated in plasma of C57BL/6 mice 2 h after experimental mono- and polytrauma as well as in polytrauma patients (ISS ≥ 18) during a 10-day period. Correlation analyses were performed to indicate a linkage between JAM-1 plasma concentrations and organ failure. JAM-1 was systemically detected after experimental trauma in mice with blunt chest trauma as a driving force. Accordingly, JAM-1 was reduced in lung tissue after pulmonary contusion and JAM-1 plasma levels significantly correlated with increased protein levels in the bronchoalveolar lavage as a sign for alveolocapillary barrier dysfunction. Furthermore, JAM-1 was markedly released into the plasma of polytrauma patients as early as 4 h after the trauma insult and significantly correlated with severity of disease and organ dysfunction (APACHE II and SOFA score). The data support an early injury- and time-dependent appearance of the barrier molecule JAM-1 in the circulation indicative of a commencing trauma-induced barrier dysfunction. PMID:26556956

Overview of Glenn Mechanical Components Branch Research

NASA Astrophysics Data System (ADS)

Zakrajsek, James

2002-09-01

Mr. James Zakrajsek, chief of the Mechanical Components Branch, gave an overview of research conducted by the branch. Branch members perform basic research on mechanical components and systems, including gears and bearings, turbine seals, structural and thermal barrier seals, and space mechanisms. The research is focused on propulsion systems for present and advanced aerospace vehicles. For rotorcraft and conventional aircraft, we conduct research to develop technology needed to enable the design of low noise, ultra safe geared drive systems. We develop and validate analytical models for gear crack propagation, gear dynamics and noise, gear diagnostics, bearing dynamics, and thermal analyses of gear systems using experimental data from various component test rigs. In seal research we develop and test advanced turbine seal concepts to increase efficiency and durability of turbine engines. We perform experimental and analytical research to develop advanced thermal barrier seals and structural seals for current and next generation space vehicles. Our space mechanisms research involves fundamental investigation of lubricants, materials, components and mechanisms for deep space and planetary environments.

Microfibre barrier laundry adds value.

PubMed

Fryer, Kurt

2011-04-01

London's Guy's and St Thomas' NHS Foundation Trust has installed a complete barrier laundry system from Electrolux Professional at its St Thomas' Hospital location for specialist washing of an estimated 7,000 microfibre cloths and 5,000 microfibre mops each day from both the St Thomas' and Guy's Hospital sites. Since the installation, as Electrolux Professional national account manager Kurt Fryer reports, the "cost-effective" equipment's high performance has seen laundry staff achieve a significant increase in productivity.

Development of an ultrahigh-performance infrared detector platform for advanced spectroscopic sensing systems

NASA Astrophysics Data System (ADS)

Jain, Manish; Wicks, Gary; Marshall, Andrew; Craig, Adam; Golding, Terry; Hossain, Khalid; McEwan, Ken; Howle, Chris

2014-05-01

Laser-based stand-off sensing of threat agents (e.g. explosives, toxic industrial chemicals or chemical warfare agents), by detection of distinct infrared spectral absorption signature of these materials, has made significant advances recently. This is due in part to the availability of infrared and terahertz laser sources with significantly improved power and tunability. However, there is a pressing need for a versatile, high performance infrared sensor that can complement and enhance the recent advances achieved in laser technology. This work presents new, high performance infrared detectors based on III-V barrier diodes. Unipolar barrier diodes, such as the nBn, have been very successful in the MWIR using InAs(Sb)-based materials, and in the MWIR and LWIR using type-II InAsSb/InAs superlattice-based materials. This work addresses the extension of the barrier diode architecture into the SWIR region, using GaSb-based and InAs-based materials. The program has resulted in detectors with unmatched performance in the 2-3 μm spectral range. Temperature dependent characterization has shown dark currents to be diffusion limited and equal to, or within a factor of 5, of the Rule 07 expression for Auger-limited HgCdTe detectors. Furthermore, D* values are superior to those of existing detectors in the 2-3 μm band. Of particular significance to spectroscopic sensing systems is the ability to have near-background limited performance at operation temperatures compatible with robust and reliable solid state thermoelectric coolers.

Training + Technology: The Future Is Now.

ERIC Educational Resources Information Center

Heathman, Dena J.; Kleiner, Brian H.

1991-01-01

New applications of computer-assisted training being developed include telecommunications, artificial intelligence, soft skills training, and performance support systems. Barriers to acceptance are development time, costs, and lack of human contact. (SK)

Double barrier system for an in situ conversion process

DOEpatents

McKinzie, Billy John [Houston, TX; Vinegar, Harold J [Bellaire, TX; Cowan, Kenneth Michael [Sugar land, TX; Deeg, Wolfgang Friedrich Johann [Houston, TX; Wong, Sau-Wai [Rijswijk, NL

2009-05-05

A barrier system for a subsurface treatment area is described. The barrier system includes a first barrier formed around at least a portion of the subsurface treatment area. The first barrier is configured to inhibit fluid from exiting or entering the subsurface treatment area. A second barrier is formed around at least a portion of the first barrier. A separation space exists between the first barrier and the second barrier.

Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Halbig, Michael Charles; Puleo, Bernadette J.; Costa, Gustavo; Mccue, Terry R.

2017-01-01

This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiC-SiC Ceramic Matrix Composite (CMC) combustors particularly under the NASA Environmentally Responsible Aviation, Fundamental Aeronautics and Transformative Aeronautics Concepts Programs. The emphases have been placed on the current design challenges of the 2700-3000F capable environmental barrier coatings for low NOX emission combustors for next generation turbine engines by using advanced plasma spray based processes, and the coating processing and integration with SiC-SiC CMCs and component systems. The developments also have included candidate coating composition system designs, degradation mechanisms, performance evaluation and down-selects; the processing optimizations using TriplexPro Air Plasma Spray Low Pressure Plasma Spray (LPPS), Plasma Spray Physical Vapor Deposition and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements under the NASA development programs, as demonstrated in the simulated engine high heat flux, combustion environments, in conjunction with high heat flux, mechanical creep and fatigue loading testing conditions.

Experimental investigation of terahertz quantum cascade laser with variable barrier heights

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Aiting; Vijayraghavan, Karun; Belkin, Mikhail A., E-mail: mbelkin@ece.utexas.edu

2014-04-28

We report an experimental study of terahertz quantum cascade lasers with variable barrier heights based on the Al{sub x}Ga{sub 1–x}As/GaAs material system. Two new designs are developed based on semiclassical ensemble Monte Carlo simulations using state-of-the-art Al{sub 0.15}Ga{sub 0.85}As/GaAs three-quantum-well resonant phonon depopulation active region design as a reference. The new designs achieved maximum lasing temperatures of 188 K and 172 K, as compared to the maximum lasing temperature of 191 K for the reference structure. These results demonstrate that terahertz quantum cascade laser designs with variable barrier heights provide a viable alternative to the traditional active region designs with fixed barrier composition.more » Additional design space offered by using variable barriers may lead to future improvements in the terahertz quantum cascade laser performance.« less

Barriers of lean construction implementation in the Moroccan construction industry

NASA Astrophysics Data System (ADS)

Bajjou, Mohamed Saad; Chafi, Anas

2018-04-01

Improving the production system performance has become a fundamental pillar that must be taken into consideration in the construction industry. Recent developments in the construction sector have led to renewed interest in new techniques of management. Lean Construction is a very effective approach that has gained a high popularity by its ability to eliminate waste and maximize the value for the customer. Although both developed and developing countries have gained large benefits by implementing Lean Construction approach, several experiences showed many barriers that are hindering its implementation especially in developing countries. This paper aims to assess the critical barriers to the successful implementation in the Moroccan construction industry. Based on a literature review, followed by an analysis of data collected from a questionnaire survey which targeted 330 practitioners in the Moroccan construction field, several barriers were identified as key barriers. The findings of this investigation revealed that there are significant barriers such as Lack of knowledge about Lean Construction concepts, Unskilled Human Resources, and insufficient financial resources.

Performance Monitoring: Evaluating an Organic Carbon-Limestone PRB for Treatment of Heavy Metals and Acidity

EPA Science Inventory

Since 2004, researchers from the U.S. EPA National Risk Management Research Laboratory (NRMRL) have annually evaluated performance of an organic carbon-limestone permeable reactive barrier (PRB) system installed in 2003 by EPA Region 6 at the Delatte Metals Superfund site in Ponc...

A Comparison of HPT and Traditional Training Approaches.

ERIC Educational Resources Information Center

Kretz, Richard

2002-01-01

Focuses on the comparative use of training from human performance technology (HPT) and traditional training perspectives, based on taxonomy. Concludes that the primary difference is a holistic systems performance improvement approach by eliminating barriers with HPT versus reaction or response to a set of business objectives in traditional…

Barriers to the success of an electronic pharmacovigilance reporting system in Kenya: an evaluation three years post implementation.

PubMed

Agoro, Oscar O; Kibira, Sarah W; Freeman, Jenny V; Fraser, Hamish S F

2018-06-01

Electronic pharmacovigilance reporting systems are being implemented in many developing countries in an effort to improve reporting rates. This study sought to establish the factors that acted as barriers to the success of an electronic pharmacovigilance reporting system in Kenya 3 years after its implementation. Factors that could act as barriers to using electronic reporting systems were identified in a review of literature and then used to develop a survey questionnaire that was administered to pharmacists working in government hospitals in 6 counties in Kenya. The survey was completed by 103 out of the 115 targeted pharmacists (89.5%) and included free-text comments. The key factors identified as barriers were: unavailable, unreliable, or expensive Internet access; challenges associated with a hybrid system of paper and electronic reporting tools; and system usability issues. Coordination challenges at the national pharmacovigilance center and changes in the structure of health management in the country also had an impact on the success of the electronic reporting system. Different personal, organizational, infrastructural, and reporting system factors affect the success of electronic reporting systems in different ways, depending on the context. Context-specific formative evaluations are useful in establishing the performance of electronic reporting systems to identify problems and ensure that they achieve the desired objectives. While several factors hindered the optimal use of the electronic pharmacovigilance reporting system in Kenya, all were considered modifiable. Effort should be directed toward tackling the identified issues in order to facilitate use and improve pharmacovigilance reporting rates.

Safety of High Speed Guided Ground Transportation Systems : Intrusion Barrier Design Study

DOT National Transportation Integrated Search

1994-11-01

This report presents a study on the development of anti-intrusion systems that will perform the function of preventing a derailed railroad car or an errant highway vehicle or some type of dislodged load from intruding into the operational space of th...

Effect of deformation and orientation on spin orbit density dependent nuclear potential

NASA Astrophysics Data System (ADS)

Mittal, Rajni; Kumar, Raj; Sharma, Manoj K.

2017-11-01

Role of deformation and orientation is investigated on spin-orbit density dependent part VJ of nuclear potential (VN=VP+VJ) obtained within semi-classical Thomas Fermi approach of Skyrme energy density formalism. Calculations are performed for 24-54Si+30Si reactions, with spherical target 30Si and projectiles 24-54Si having prolate and oblate shapes. The quadrupole deformation β2 is varying within range of 0.023 ≤ β2 ≤0.531 for prolate and -0.242 ≤ β2 ≤ -0.592 for oblate projectiles. The spin-orbit dependent potential gets influenced significantly with inclusion of deformation and orientation effect. The spin-orbit barrier and position gets significantly influenced by both the sign and magnitude of β2-deformation. Si-nuclei with β22<0 have higher spin-orbit barrier (compact spin-orbit configuration) in comparison to systems with β2>0. The possible role of spin-orbit potential on barrier characteristics such as barrier height, barrier curvature and on the fusion pocket is also probed. In reference to prolate and oblate systems, the angular dependence of spin-orbit potential is further studied on fusion cross-sections.

Gas barrier properties of bio-inspired Laponite-LC polymer hybrid films.

PubMed

Tritschler, Ulrich; Zlotnikov, Igor; Fratzl, Peter; Schlaad, Helmut; Grüner, Simon; Cölfen, Helmut

2016-05-26

Bio-inspired Laponite (clay)-liquid crystal (LC) polymer composite materials with high clay fractions (>80%) and a high level of orientation of the clay platelets, i.e. with structural features similar to the ones found in natural nacre, have been shown to exhibit a promising behavior in the context of reduced oxygen transmission. Key characteristics of these bio-inspired composite materials are their high inorganic content, high level of exfoliation and orientation of the clay platelets, and the use of a LC polymer forming the organic matrix in between the Laponite particles. Each single feature may be beneficial to increase the materials gas barrier property rendering this composite a promising system with advantageous barrier capacities. In this detailed study, Laponite/LC polymer composite coatings with different clay loadings were investigated regarding their oxygen transmission rate. The obtained gas barrier performance was linked to the quality, respective Laponite content and the underlying composite micro- and nanostructure of the coatings. Most efficient oxygen barrier properties were observed for composite coatings with 83% Laponite loading that exhibit a structure similar to sheet-like nacre. Further on, advantageous mechanical properties of these Laponite/LC polymer composites reported previously give rise to a multifunctional composite system.

What are the barriers to performing nonpharmacological interventions for behavioral symptoms in the nursing home?

PubMed

Cohen-Mansfield, Jiska; Thein, Khin; Marx, Marcia S; Dakheel-Ali, Maha

2012-05-01

Behavioral symptoms are common in persons with dementia, and nonpharmacological interventions are recommended as the first line of therapy. We describe barriers to conducting nonpharmacological interventions for behavioral symptoms. A descriptive study of barriers to intervention delivery in a controlled trial. The study was conducted in six nursing homes in Maryland. Participants were 89 agitated nursing home residents with dementia. Personalized interventions were developed using the Treatment Routes for Exploring Agitation decision tree protocol. Trained research assistants prepared and delivered the interventions. Feasibility of the interventions was determined. Barriers to Intervention Delivery Assessment, activities of daily living, cognitive functioning, depressed affect, pain, observed agitation, and observed affect. Barriers were observed for the categories of resident barriers (specifically, unwillingness to participate; resident attributes, such as unresponsive), barriers related to resident unavailability (resident asleep or eating), and external barriers (staff-related barriers, family-related barriers, environmental barriers, and system process variables). Interventions pertaining to food/drink and to 1-on-1 socializing were found to have the fewest barriers, whereas higher numbers of barriers occurred with puzzles/board games and arts and crafts activities. Moreover, when successful interventions were presented to participants after the feasibility period, we noted fewer barriers, presumably because barrier identification had been used to better tailor interventions to each participant and to the environment. Knowledge of barriers provides a tool by which to tailor interventions so as to anticipate or circumvent barriers, thereby maximizing intervention delivery. Copyright © 2012 American Medical Directors Association, Inc. Published by Elsevier Inc. All rights reserved.

Fission Meter Information Barrier Attribute Measurement System: Task 1 Report: Document existing Fission Meter neutron IB system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kerr, P. L.

An SNM attribute Information Barrier (IB) system was developed for a 2011 US/UK Exercise. The system was modified and extensively tested in a 2013-2014 US-UK Measurement Campaign. This work demonstrated rapid deployment of an IB system for potential treaty use. The system utilizes an Ortec Fission Meter neutron multiplicity counter and custom computer code. The system demonstrates a proof-of-principle automated Pu-240 mass determination with an information barrier. After a software start command is issued, the system automatically acquires and downloads data, performs an analysis, and displays the results. This system conveys the results of a Pu mass threshold measurements inmore » a way the does not reveal sensitive information. In full IB mode, only red/green ‘lights’ are displayed in the software. In test mode, more detailed information is displayed. The code can also read in, analyze, and display results from previously acquired or simulated data. Because the equipment is commercial-off-the-shelf (COTS), the system demonstrates a low-cost short-lead-time technology for treaty SNM attribute measurements. A deployed system will likely require integration of additional authentication and tamper-indicating technologies. This will be discussed for the project in this and future progress reports.« less

Experimental evaluation of thermal energy storage

NASA Technical Reports Server (NTRS)

Asbury, J. G.; Hersh, H. N.

1980-01-01

The technical performance of commercially available thermal energy storage (TES) residential heating units under severe weather conditions is discussed. The benefits and costs of TES to the user and utility companies were assessed. The TES issues, research and development needs, and barriers to commercialization were identified. The field tests which determined the performance characteristics for the TES are described and the TES systems, which included both ceramic and hydronic systems, are compared.

Decontamination systems information and research program. Quarterly report, April--June 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

This report contains separate reports on the following subtasks: analysis of the Vortec cyclone melting system for remediation of PCB contaminated soils using CFD; drain enhanced soil flushing using prefabricated vertical drains; performance and characteristics evaluation of acrylates as grout barriers; development of standard test protocol barrier design models for desiccation barriers, and for in-situ formed barriers; in-situ bioremediation of chlorinated solvents at Portsmouth Gaseous Diffusion Plant; development of a decision support system and a prototype database for management of the EM50 technology development program; GIS-based infrastructure for site characterization and remediation; treatment of mixed wastes via fluidized bed steammore » reforming; use of centrifugal membrane technology to treat hazardous/radioactive waste; environmental pollution control devices based on novel forms of carbon; development of instrumental methods for analysis of nuclear wastes and environmental materials; production and testing of biosorbents and cleaning solutions for D and D; use of SpinTek centrifugal membrane and sorbents/cleaning solutions for D and D; West Virginia High Tech Consortium Foundation--Environmental support program; small business interaction opportunities; and approach for assessing potential voluntary environmental protection.« less

Self-reported use of an implanted FES hand system by adolescents with tetraplegia.

PubMed

Davis, S E; Mulcahey, M J; Smith, B T; Betz, R R

1998-07-01

The Freehand System, an eight-channel functional electrical stimulation (FES) system, was implanted in five adolescents with C-5 or C-6 tetraplegia to provide stimulated lateral pinch and palmar grasp. Following completion of inpatient training on how to use the Freehand System for predefined and self-selected activities of daily living (ADL), the adolescents were discharged to use their Freehand systems at home and school. A telephone survey was administered on a weekly basis to obtain information on the type of ADL performed with the Freehand System, reasons for not using the Freehand System, and perceived barriers and motivators to FES use. Twenty surveys were obtained on each adolescent, resulting in a total of 100 surveys. The most common type of activity performed with the Freehand System was self-care, which included tasks such as eating, grooming, and brushing teeth. The Freehand System was also used for productivity activities defined as writing, socialization, and manipulation of school and household objects. Motivators to Freehand System use included perceived need and importance to perform an ADL in an independent fashion, physical ease of using the Freehand System, and availability of social supports that facilitated Freehand System use. While there were several reported barriers to Freehand System use, incompatibility with multiple transfers to and from the wheelchair and lack of physical assistance during morning care to don the system were perceived as two of the more common reasons for nonuse.

Environmental Barrier Coatings for Turbine Engines: A Design and Performance Perspective

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis; Smialek, James L.; Miller, Robert A.

2009-01-01

Ceramic thermal and environmental barrier coatings (TEBC) for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating long-term durability remains a major concern with the ever-increasing temperature, strength and stability requirements in engine high heat-flux combustion environments, especially for highly-loaded rotating turbine components. Advanced TEBC systems, including nano-composite based HfO2-aluminosilicate and rare earth silicate coatings are being developed and tested for higher temperature capable SiC/SiC ceramic matrix composite (CMC) turbine blade applications. This paper will emphasize coating composite and multilayer design approach and the resulting performance and durability in simulated engine high heat-flux, high stress and high pressure combustion environments. The advances in the environmental barrier coating development showed promise for future rotating CMC blade applications.

Thermal barrier coatings issues in advanced land-based gas turbines

NASA Technical Reports Server (NTRS)

Parks, W. P.; Lee, W. Y.; Wright, I. G.

1995-01-01

The Department of Energy's Advanced Turbine System (ATS) program is aimed at forecasting the development of a new generation of land-based gas turbine systems with overall efficiencies significantly beyond those of current state-of-the-art machines, as well as greatly increased times between inspection and refurbishment, improved environmental impact, and decreased cost. The proposed duty cycle of ATS turbines will require the use of different criteria in the design of the materials for the critical hot gas path components. In particular, thermal barrier coatings will be an essential feature of the hot gas path components in these machines. While such coatings are routinely used in high-performance aircraft engines and are becoming established in land-based turbines, the requirements of the ATS turbine application are sufficiently different that significant improvements in thermal barrier coating technology will be necessary. In particular, it appears that thermal barrier coatings will have to function on all airfoil sections of the first stage vanes and blades to provide the significant temperature reduction required. In contrast, such coatings applied to the blades and vances of advanced aircraft engines are intended primarily to reduce air cooling requirements and extend component lifetime; failure of those coatings can be tolerated without jeopardizing mechanical or corrosion performance. A major difference is that in ATS turbines these components will be totally reliant on thermal barrier coatings which will, therefore, need to be highly reliable even over the leading edges of first stage blades. Obviously, the ATS program provides a very challenging opportunity for TBC's, and involves some significant opportunities to extend this technology.

Implementing clinical governance in English primary care groups/trusts: reconciling quality improvement and quality assurance

PubMed Central

Campbell, S; Sheaff, R; Sibbald, B; Marshall, M; Pickard, S; Gask, L; Halliwell, S; Rogers, A; Roland, M

2002-01-01

Objectives: To investigate the concept of clinical governance being advocated by primary care groups/trusts (PCG/Ts), approaches being used to implement clinical governance, and potential barriers to its successful implementation in primary care. Design: Qualitative case studies using semi-structured interviews and documentation review. Setting: Twelve purposively sampled PCG/Ts in England. Participants: Fifty senior staff including chief executives, clinical governance leads, mental health leads, and lay board members. Main outcome measures: Participants' perceptions of the role of clinical governance in PCG/Ts. Results: PCG/Ts recognise that the successful implementation of clinical governance in general practice will require cultural as well as organisational changes, and the support of practices. They are focusing their energies on supporting practices and getting them involved in quality improvement activities. These activities include, but move beyond, conventional approaches to quality assessment (audit, incentives) to incorporate approaches which emphasise corporate and shared learning. PCG/Ts are also engaged in setting up systems for monitoring quality and for dealing with poor performance. Barriers include structural barriers (weak contractual levers to influence general practices), resource barriers (perceived lack of staff or money), and cultural barriers (suspicion by practice staff or problems overcoming the perceived blame culture associated with quality assessment). Conclusion: PCG/Ts are focusing on setting up systems for implementing clinical governance which seek to emphasise developmental and supportive approaches which will engage health professionals. Progress is intentionally incremental but formidable challenges lie ahead, not least reconciling the dual role of supporting practices while monitoring (and dealing with poor) performance. PMID:12078380

Integrated health systems.

PubMed

Shortell, Stephen M; McCurdy, Rodney K

2010-01-01

Before meaningful gains in improving the value of health care in the US can be achieved, the fragmented nature in which health care is financed and delivered must be addressed. One type of healthcare organization, the Integrated Delivery System (IDS), is poised to play a pivotal role in reform efforts. What are these systems? What is the current evidence regarding their performance? What are the current barriers to their establishment and how can these barriers be removed? This chapter addresses these important questions. Although there are many types of IDS' in the US healthcare landscape, the chapter begins by identifying the necessary healthcare components that encompass an IDS and discusses the levels of integration that are important to improving health care quality and value. Next, it explores the recent evidence regarding IDS performance which, while generally positive, is less than what it could be if there were greater focus on clinical integration. To highlight, the chapter discusses the efficacy of system engineering initiatives in two examples of large, fully integrated systems: Kaiser-Permanente and the Veterans Health Administration. The evidence here is strong that the impact of system engineering methods is enhanced through the integration of processes, goals and outcomes. Reforms necessary to encourage the development of IDS' include: 1) the development of payment mechanisms designed to increase greater inter-dependency of hospitals and physicians; 2) the modification or removal of several regulatory barriers to greater clinical integration; and 3) the establishment of a more robust data collection and reporting system to increase transparency and accountability. The chapter concludes with a framework for considering these reforms across strategic, structural, cultural, and technical dimensions.

Can You Hear Me Now? Come in Loud and Clear with a Wireless Classroom Audio System

ERIC Educational Resources Information Center

Smith, Mark

2006-01-01

As school performance under NCLB becomes increasingly important, districts can not afford to have barriers to learning. That is where wireless sound-field amplification systems come into play. Wireless sound-field amplification systems come in two types: radio frequency (RF) and infrared (IR). RF systems are based on FCC-approved FM and UHF bands…

Enhanced numerical analysis of three-color HgCdTe detectors

NASA Astrophysics Data System (ADS)

Jóźwikowski, K.; Rogalski, A.

2007-04-01

The performance of three-color HgCdTe photovoltaic heterostructure detector is examined theoretically. In comparison with two-color detectors with two back-to-back junctions, three-color structure contain an absorber of intermediate wavelength placed between two junctions, and electronic barriers are used to isolate this intermediate region. This structure was first proposed by British workers. Enhanced original computer programs are applied to solve the system of non-linear continuity equations for carriers and Poisson equations. In addition, the numerical analysis includes the dependence of absorption coefficient on Burstein effect as well as interference effects in heterostructure with metallic electrical contacts. Three detector structures with different localizations of separating barriers are analyzed. The calculations results are presented in the form of spatial distributions of bandgap energy and quantum efficiency. It is shown that the performance of the detector is critically dependent on the barrier's doping level and position in relation to the junction. This behavior is serious disadvantage of the considered three color detector. A small shift of the barrier location and doping level causes serious changes in spectral responsivity.

Combined acoustical and visual performance of noise barriers in mitigating the environmental impact of motorways.

PubMed

Jiang, Like; Kang, Jian

2016-02-01

This study investigated the overall performance of noise barriers in mitigating environmental impact of motorways, taking into consideration their effects on reducing noise and visual intrusions of moving traffic, but also potentially inducing visual impact themselves. A laboratory experiment was carried out, using computer-visualised video scenes and motorway traffic noise recordings to present experimental scenarios covering two traffic levels, two distances of receiver to road, two types of background landscape, and five barrier conditions including motorway only, motorway with tree belt, motorways with 3 m timber barrier, 5m timber barrier, and 5m transparent barrier. Responses from 30 participants of university students were gathered and perceived barrier performance analysed. The results show that noise barriers were always beneficial in mitigating environmental impact of motorways, or made no significant changes in environmental quality when the impact of motorways was low. Overall, barriers only offered similar mitigation effect as compared to tree belt, but showed some potential to be more advantageous when traffic level went high. 5m timber barrier tended to perform better than the 3m one at the distance of 300 m but not at 100 m possibly due to its negative visual effect when getting closer. The transparent barrier did not perform much differently from the timber barriers but tended to be the least effective in most scenarios. Some low positive correlations were found between aesthetic preference for barriers and environmental impact reduction by the barriers. Copyright © 2015 Elsevier B.V. All rights reserved.

Influence of glioma cells on a new co-culture in vitro blood-brain barrier model for characterization and validation of permeability.

PubMed

Mendes, Bárbara; Marques, Cláudia; Carvalho, Isabel; Costa, Paulo; Martins, Susana; Ferreira, Domingos; Sarmento, Bruno

2015-07-25

The blood-brain barrier plays an important role in protecting the brain from injury and diseases, but also restrains the delivery of potential therapeutic drugs for the treatment of brain illnesses, such as tumors. Glioma is most common cancer type of central nervous system in adults and the most lethal in children. The treatment is normally poor and ineffective. To better understand the ability of drug delivery systems to permeate this barrier, a blood-brain barrier model using human brain endothelial cells and a glioma cell line is herein proposed. The consistent trans-endothelial electrical values, immunofluorescence and scanning electronic microscopy showed a confluent endothelial cell monolayer with high restrictiveness. Upon inclusion of glioma cell line, the trans-endothelial electrical resistance decreased, with consequent increase of apparent permeability of fluorescein isothiocyanate dextran used as model drug, revealing a reduction of the barrier robustness. In addition, it was demonstrated a cell shape modification in the co-culture, with loss of tight junctions. The microenvironment of co-cultured model presented significant increase of of CCL2/MCP-1 and IL-6 production, correlating with the modulation of permeation. The results encourage the use of the proposed in vitro model as a screening tool when performing drugs permeability for the treatment of disorders among the central nervous system. Copyright © 2015 Elsevier B.V. All rights reserved.

Thermal Gradient Cyclic Behavior of a Thermal/Environmental Barrier Coating System on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Lee, Kang N.; Miller, Robert A.

2002-01-01

Thermal barrier and environmental barrier coatings (TBCs and EBCs) will play a crucial role in future advanced gas turbine engines because of their ability to significantly extend the temperature capability of the ceramic matrix composite (CMC) engine components in harsh combustion environments. In order to develop high performance, robust coating systems for effective thermal and environmental protection of the engine components, appropriate test approaches for evaluating the critical coating properties must be established. In this paper, a laser high-heat-flux, thermal gradient approach for testing the coatings will be described. Thermal cyclic behavior of plasma-sprayed coating systems, consisting of ZrO2-8wt%Y2O3 thermal barrier and NASA Enabling Propulsion Materials (EPM) Program developed mullite+BSAS/Si type environmental barrier coatings on SiC/SiC ceramic matrix composites, was investigated under thermal gradients using the laser heat-flux rig in conjunction with the furnace thermal cyclic tests in water-vapor environments. The coating sintering and interface damage were assessed by monitoring the real-time thermal conductivity changes during the laser heat-flux tests and by examining the microstructural changes after the tests. The coating failure mechanisms are discussed based on the cyclic test results and are correlated to the sintering, creep, and thermal stress behavior under simulated engine temperature and heat flux conditions.

The Pharmacogenomics Research Network Translational Pharmacogenetics Program: Outcomes and Metrics of Pharmacogenetic Implementations Across Diverse Healthcare Systems.

PubMed

Luzum, J A; Pakyz, R E; Elsey, A R; Haidar, C E; Peterson, J F; Whirl-Carrillo, M; Handelman, S K; Palmer, K; Pulley, J M; Beller, M; Schildcrout, J S; Field, J R; Weitzel, K W; Cooper-DeHoff, R M; Cavallari, L H; O'Donnell, P H; Altman, R B; Pereira, N; Ratain, M J; Roden, D M; Embi, P J; Sadee, W; Klein, T E; Johnson, J A; Relling, M V; Wang, L; Weinshilboum, R M; Shuldiner, A R; Freimuth, R R

2017-09-01

Numerous pharmacogenetic clinical guidelines and recommendations have been published, but barriers have hindered the clinical implementation of pharmacogenetics. The Translational Pharmacogenetics Program (TPP) of the National Institutes of Health (NIH) Pharmacogenomics Research Network was established in 2011 to catalog and contribute to the development of pharmacogenetic implementations at eight US healthcare systems, with the goal to disseminate real-world solutions for the barriers to clinical pharmacogenetic implementation. The TPP collected and normalized pharmacogenetic implementation metrics through June 2015, including gene-drug pairs implemented, interpretations of alleles and diplotypes, numbers of tests performed and actionable results, and workflow diagrams. TPP participant institutions developed diverse solutions to overcome many barriers, but the use of Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines provided some consistency among the institutions. The TPP also collected some pharmacogenetic implementation outcomes (scientific, educational, financial, and informatics), which may inform healthcare systems seeking to implement their own pharmacogenetic testing programs. © 2017, The American Society for Clinical Pharmacology and Therapeutics.

Assessment of sodium conductor distribution cable

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1979-06-01

The study assesses the barriers and incentives for using sodium conductor distribution cable. The assessment considers environmental, safety, energy conservation, electrical performance and economic factors. Along with all of these factors considered in the assessment, the sodium distribution cable system is compared to the present day alternative - an aluminum conductor system. (TFD)

Evaluating the Longevity and Hydraulic Performance of Permeable Reactive Barriers at Department of Defense Sites

DTIC Science & Technology

2002-04-24

F inal Repor t Evaluating the Longevity and Hydraulic Performance of Permeable Reactive Barriers at Department of Defense Sites P1·epared for... Hydraulic Performance of Permeable Reactive Barriers at Department of Defense Sites Prepared for Project Officer: Charles Reeter Naval Facilities...SUBTITLE 5a. CONTRACT NUMBER Evaluating the Longevity and Hydraulic Performance of Permeable Reactive N4 7408-95-D-0730/0087 Barriers at Department of

Exploring the impact of financial barriers on secondary prevention of heart disease.

PubMed

Dhaliwal, Kirnvir K; King-Shier, Kathryn; Manns, Braden J; Hemmelgarn, Brenda R; Stone, James A; Campbell, David J T

2017-02-14

Patients with coronary artery disease experience various barriers which impact their ability to optimally manage their condition. Financial barriers may result in cost related non-adherence to medical therapies and recommendations, impacting patient health outcomes. Patient experiences regarding financial barriers remain poorly understood. Therefore, we used qualitative methods to explore the experience of financial barriers to care among patients with heart disease. We conducted a qualitative descriptive study of participants in Alberta, Canada with heart disease (n = 13) who perceived financial barriers to care. We collected data using semi-structured face-to-face or telephone interviews inquiring about patients experience of financial barriers and the strategies used to cope with such barriers. Multiple analysts performed inductive thematic analysis and findings were bolstered by member checking. The aspects of care to which participants perceived financial barriers included access to: medications, cardiac rehabilitation and exercise, psychological support, transportation and parking. Some participants demonstrated the ability to successfully self-advocate in order to effectively navigate within the healthcare and social service systems. Financial barriers impacted patients' ability to self-manage their cardiovascular disease. Financial barriers contributed to non-adherence to essential medical therapies and health recommendations, which may lead to adverse patient outcomes. Given that it is such a key skill, enhancing patients' self-advocacy and navigation skills may assist in improving patient health outcomes.

Effect of Layer-Graded Bond Coats on Edge Stress Concentration and Oxidation Behavior of Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Ghosn, Louis J.; Miller, Robert A.

1998-01-01

Thermal barrier coating (TBC) durability is closely related to design, processing and microstructure of the coating Z, tn systems. Two important issues that must be considered during the design of a thermal barrier coating are thermal expansion and modulus mismatch between the substrate and the ceramic layer, and substrate oxidation. In many cases, both of these issues may be best addressed through the selection of an appropriate bond coat system. In this study, a low thermal expansion and layer-graded bond coat system, that consists of plasma-sprayed FeCoNiCrAl and FeCrAlY coatings, and a high velocity oxyfuel (HVOF) sprayed FeCrAlY coating, is developed to minimize the thermal stresses and provide oxidation resistance. The thermal expansion and oxidation behavior of the coating system are also characterized, and the strain isolation effect of the bond coat system is analyzed using the finite element method (FEM). Experiments and finite element results show that the layer-graded bond coat system possesses lower interfacial stresses. better strain isolation and excellent oxidation resistance. thus significantly improving the coating performance and durability.

Multilayer thermal barrier coating systems

DOEpatents

Vance, Steven J.; Goedjen, John G.; Sabol, Stephen M.; Sloan, Kelly M.

2000-01-01

The present invention generally describes multilayer thermal barrier coating systems and methods of making the multilayer thermal barrier coating systems. The thermal barrier coating systems comprise a first ceramic layer, a second ceramic layer, a thermally grown oxide layer, a metallic bond coating layer and a substrate. The thermal barrier coating systems have improved high temperature thermal and chemical stability for use in gas turbine applications.

Stochastic Spiking Neural Networks Enabled by Magnetic Tunnel Junctions: From Nontelegraphic to Telegraphic Switching Regimes

NASA Astrophysics Data System (ADS)

Liyanagedera, Chamika M.; Sengupta, Abhronil; Jaiswal, Akhilesh; Roy, Kaushik

2017-12-01

Stochastic spiking neural networks based on nanoelectronic spin devices can be a possible pathway to achieving "brainlike" compact and energy-efficient cognitive intelligence. The computational model attempt to exploit the intrinsic device stochasticity of nanoelectronic synaptic or neural components to perform learning or inference. However, there has been limited analysis on the scaling effect of stochastic spin devices and its impact on the operation of such stochastic networks at the system level. This work attempts to explore the design space and analyze the performance of nanomagnet-based stochastic neuromorphic computing architectures for magnets with different barrier heights. We illustrate how the underlying network architecture must be modified to account for the random telegraphic switching behavior displayed by magnets with low barrier heights as they are scaled into the superparamagnetic regime. We perform a device-to-system-level analysis on a deep neural-network architecture for a digit-recognition problem on the MNIST data set.

Performance evaluation of experimental highway noise barriers

DOT National Transportation Integrated Search

1994-05-01

During the period October 1986 through April 1994, the U.S. Department of Transportation, Research and Special Programs Administration, John A. Volpe National Transportation Systems Center, in support of the Federal Highway Administration and 17 spon...

Energy and Environment 1990: Transportation-induced noise and air pollution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-01-01

Contents: public reaction to low levels of aircraft noise; airport noise insulation of homes surrounding stapleton international airport; sound insulation and thermal performance modifications: case study for three dwellings near bwi airport; single-number ratings for outdoor-indoor sound insulation; control of wheel squeal noise in rail transit cars; knowledge-based preprocessor for traffic noise prediction; barrier overlap analysis procedure; atmospheric effects on traffic noise propagation; predicting stop-and-go traffic noise with stamina 2.0; feasibility of transparent noise barriers; field testing of the effectiveness of open-graded asphalt pavement in reducing tire noise from highway vehicles; cost of noise barrier construction in the united states;more » comparisons of emissions of transit buses using methanol and diesel fuel; high-speed rail system noise assessment; energy-related, environmental, and economic benefits of florida's high-speed rail and maglev systems proposals.« less

Performance Stability of Silicone Oxide-Coated Plastic Parenteral Vials.

PubMed

Weikart, Christopher M; Pantano, Carlo G; Shallenberger, Jeff R

2017-01-01

A new packaging system was developed for parenteral pharmaceuticals that combines the best attributes of plastic and glass without their respective drawbacks. This technological advancement is based on the synergy between high-precision injection-molded plastics and plasma coating technology. The result is a shatter-resistant, optically clear, low-particulate, and chemically durable packaging system. The demand for this product is driven by the expanding market, regulatory constraints, and product recalls for injectable drugs and biologics packaged in traditional glass materials. It is shown that this new packaging system meets or exceeds the important performance characteristics of glass, especially in eliminating the glass delamination and breakage that has been observed in many products. The new packaging system is an engineered, multilayer, glass-coated plastic composite that provides a chemically stable contact surface and oxygen barrier performance that exceeds a 2 year shelf life requirement. Evaluation of the coating system characteristics and performance stability to chemical, temperature, and mechanical extremes are reported herein. LAY ABSTRACT: A new packaging system for parenteral pharmaceuticals was developed that combines the best attributes of plastic and glass without their respective drawbacks. This technological advancement is based on the synergy between high-precision injection-molded plastics and plasma coating technology. The result is a shatter-resistant, optically clear, low-particulate, and chemically durable packaging system. It is shown that this new packaging system meets or exceeds the important performance characteristics of glass, especially in eliminating the glass delamination and breakage that has been observed in many products. The new packaging system is an engineered, multilayer, glass-coated plastic composite that provides a chemically stable contact surface and oxygen barrier performance that exceeds a 2 year shelf life requirement. Evaluation of the coating system characteristics and performance stability to chemical, temperature, and mechanical extremes are reported herein. © PDA, Inc. 2017.

Using dissolved gas analysis to investigate the performance of an organic carbon permeable reactive barrier for the treatment of mine drainage

USGS Publications Warehouse

Williams, R.L.; Mayer, K.U.; Amos, R.T.; Blowes, D.W.; Ptacek, C.J.; Bain, J.G.

2007-01-01

The strongly reducing nature of permeable reactive barrier (PRB) treatment materials can lead to gas production, potentially resulting in the formation of gas bubbles and ebullition. Degassing in organic C based PRB systems due to the production of gases (primarily CO2 and CH4) is investigated using the depletion of naturally occurring non-reactive gases Ar and N2, to identify, confirm, and quantify chemical and physical processes. Sampling and analysis of dissolved gases were performed at the Nickel Rim Mine Organic Carbon PRB, which was designed for the treatment of groundwater contaminated by low quality mine drainage characterized by slightly acidic pH, and elevated Fe(II) and SO4 concentrations. A simple 4-gas degassing model was used to analyze the dissolved gas data, and the results indicate that SO4 reduction is by far the dominant process of organic C consumption within the barrier. The data provided additional information to delineate rates of microbially mediated SO4 reduction and confirm the presence of slow and fast flow zones within the barrier. Degassing was incorporated into multicomponent reactive transport simulations for the barrier and the simulations were successful in reproducing observed dissolved gas trends.

Distributed rendering for multiview parallax displays

NASA Astrophysics Data System (ADS)

Annen, T.; Matusik, W.; Pfister, H.; Seidel, H.-P.; Zwicker, M.

2006-02-01

3D display technology holds great promise for the future of television, virtual reality, entertainment, and visualization. Multiview parallax displays deliver stereoscopic views without glasses to arbitrary positions within the viewing zone. These systems must include a high-performance and scalable 3D rendering subsystem in order to generate multiple views at real-time frame rates. This paper describes a distributed rendering system for large-scale multiview parallax displays built with a network of PCs, commodity graphics accelerators, multiple projectors, and multiview screens. The main challenge is to render various perspective views of the scene and assign rendering tasks effectively. In this paper we investigate two different approaches: Optical multiplexing for lenticular screens and software multiplexing for parallax-barrier displays. We describe the construction of large-scale multi-projector 3D display systems using lenticular and parallax-barrier technology. We have developed different distributed rendering algorithms using the Chromium stream-processing framework and evaluate the trade-offs and performance bottlenecks. Our results show that Chromium is well suited for interactive rendering on multiview parallax displays.

Preparation of silica nanoparticles loaded with nootropics and their in vivo permeation through blood-brain barrier.

PubMed

Jampilek, Josef; Zaruba, Kamil; Oravec, Michal; Kunes, Martin; Babula, Petr; Ulbrich, Pavel; Brezaniova, Ingrid; Opatrilova, Radka; Triska, Jan; Suchy, Pavel

2015-01-01

The blood-brain barrier prevents the passage of many drugs that target the central nervous system. This paper presents the preparation and characterization of silica-based nanocarriers loaded with piracetam, pentoxifylline, and pyridoxine (drugs from the class of nootropics), which are designed to enhance the permeation of the drugs from the circulatory system through the blood-brain barrier. Their permeation was compared with non-nanoparticle drug substances (bulk materials) by means of an in vivo model of rat brain perfusion. The size and morphology of the nanoparticles were characterized by transmission electron microscopy. The content of the drug substances in silica-based nanocarriers was analysed by elemental analysis and UV spectrometry. Microscopic analysis of visualized silica nanocarriers in the perfused brain tissue was performed. The concentration of the drug substances in the tissue was determined by means of UHPLC-DAD/HRMS LTQ Orbitrap XL. It was found that the drug substances in silica-based nanocarriers permeated through the blood brain barrier to the brain tissue, whereas bulk materials were not detected in the brain.

Preparation of Silica Nanoparticles Loaded with Nootropics and Their In Vivo Permeation through Blood-Brain Barrier

PubMed Central

Zaruba, Kamil; Kunes, Martin; Ulbrich, Pavel; Brezaniova, Ingrid; Triska, Jan; Suchy, Pavel

2015-01-01

The blood-brain barrier prevents the passage of many drugs that target the central nervous system. This paper presents the preparation and characterization of silica-based nanocarriers loaded with piracetam, pentoxifylline, and pyridoxine (drugs from the class of nootropics), which are designed to enhance the permeation of the drugs from the circulatory system through the blood-brain barrier. Their permeation was compared with non-nanoparticle drug substances (bulk materials) by means of an in vivo model of rat brain perfusion. The size and morphology of the nanoparticles were characterized by transmission electron microscopy. The content of the drug substances in silica-based nanocarriers was analysed by elemental analysis and UV spectrometry. Microscopic analysis of visualized silica nanocarriers in the perfused brain tissue was performed. The concentration of the drug substances in the tissue was determined by means of UHPLC-DAD/HRMS LTQ Orbitrap XL. It was found that the drug substances in silica-based nanocarriers permeated through the blood brain barrier to the brain tissue, whereas bulk materials were not detected in the brain. PMID:26075264

An Electromagnetic/Capacitive Composite Sensor for Testing of Thermal Barrier Coatings

PubMed Central

Ren, Yuan; Pan, Mengchun; Chen, Dixiang; Tian, Wugang

2018-01-01

Thermal barrier coatings (TBCs) can significantly reduce the operating temperature of the aeroengine turbine blade substrate, and their testing technology is very urgently demanded. Due to their complex multi-layer structure, it is hard to evaluate TBCs with a single function sensor. In this paper, an electromagnetic/capacitive composite sensor is proposed for the testing of thermal barrier coatings. The dielectric material is tested with planar capacitor, and the metallic material is tested with electromagnetic coils. Then, the comprehensive test and evaluation of thermal barrier coating system can be realized. The sensor is optimized by means of theoretical and simulation analysis, and the interaction between the planar capacitor and the electromagnetic coil is studied. The experimental system is built based on an impedance analyser and multiplex unit to evaluate the performance of the composite sensor. The transimpedances and capacitances are measured under different coating parameters, such as thickness and permittivity of top coating as well as bond layer conductivity. The experimental results agree with the simulation analysis, and the feasibility of the sensor is proved. PMID:29783746

Monitoring long-term evolution of engineered barrier systems using magnets: Magnetic response.

PubMed

Rigonat, N; Isnard, O; Harley, S L; Butler, I B

2018-01-05

Remote and non-destructive monitoring of the stability and performance of Engineered Barrier Systems for Geological Disposal Facility of is gaining considerable importance in establishing the safety cases for Higher Activity Wastes disposal. This study offers an innovative use of mineral magnetism for monitoring groundwater saturation of the barrier. Four mixtures of permanent magnets (Nd-Fe-B, coated and uncoated; SmCo and AlNiCo) and bentonite were reacted for 4, 8 and 12 months with mildly-saline, high-pH leachates, representing the fluids saturating a time-evolved engineered barrier. Coupled hysteresis and thermomagnetic analyses demonstrate how Nd-Fe-B feature a time-dependent transition from square-like ferromagnetic to superparamagnetic loop via pot-bellied and wasp-waist loops, whereas SmCo and AlNiCo do not show so extensive corrosion-related variations of the intrinsic and extrinsic magnetic properties. This study allowed to identify magnetic materials suitable for shorter- (Nd-Fe-B) and longer-term (SmCo and AlNiCo) monitoring purposes. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Research gaps in routine health information system design barriers to data quality and use in low- and middle-income countries: A literature review.

PubMed

Kumar, Manish; Gotz, David; Nutley, Tara; Smith, Jason B

2018-01-01

Despite the potential impact of health information system (HIS) design barriers on health data quality and use and, ultimately, health outcomes in low- and middle-income countries (LMICs), no comprehensive literature review has been conducted to study them in this context. We therefore conducted a formal literature review to understand system design barriers to data quality and use in LMICs and to identify any major research gaps related understanding how system design affects data use. We conducted an electronic search across 4 scientific databases-PubMed, Web of Science, Embase, and Global Health-and consulted a data use expert. Following a systematic inclusion and exclusion process, 316 publications (316 abstracts and 18 full papers) were included in the review. We found a paucity of scientific publications that explicitly describe system design factors that hamper data quality or data use for decision making. Although user involvement, work flow, human-computer interactions, and user experience are critical aspects of system design, our findings suggest that these issues are not discussed or conceptualized in the literature. Findings also showed that individual training efforts focus primarily on imparting data analysis skills. The adverse impact of HIS design barriers on data integrity and health system performance may be even bigger in LMICs than elsewhere, leading to errors in population health management and clinical care. We argue for integrating systems thinking into HIS strengthening efforts to reduce the HIS design-user reality gap. Copyright © 2017 John Wiley & Sons, Ltd.

Practice patterns when treating patients with low back pain: a survey of physical therapists.

PubMed

Davies, Claire; Nitz, Arthur J; Mattacola, Carl G; Kitzman, Patrick; Howell, Dana; Viele, Kert; Baxter, David; Brockopp, Dorothy

2014-08-01

Low back pain (LBP), is a common musculoskeletal problem, affecting 75-85% of adults in their lifetime. Direct costs of LBP in the USA were estimated over 85 billion dollars in 2005 resulting in a significant economic burden for the healthcare system. LBP classification systems and outcome measures are available to guide physical therapy assessments and intervention. However, little is known about which, if any, physical therapists use in clinical practice. The purpose of this study was to identify the use of and barriers to LBP classification systems and outcome measures among physical therapists in one state. A mixed methods study using a cross-sectional cohort design with descriptive qualitative methods was performed. A survey collected both quantitative and qualitative data relevant to classification systems and outcome measures used by physical therapists working with patients with LBP. Physical therapists responded using classification systems designed to direct treatment predominantly. The McKenzie method was the most frequent approach to classify LBP. Barriers to use of classification systems and outcome measures were lack of knowledge, too limiting and time. Classification systems are being used for decision-making in physical therapy practice for patients with LBP. Lack of knowledge and training seems to be the main barrier to the use of classification systems in practice. The Oswestry Disability Index and Numerical Pain Scale were the most commonly used outcome measures. The main barrier to their use was lack of time. Continuing education and reading the literature were identified as important tools to teach evidence-based practice to physical therapists in practice.

FY2014 Propulsion Materials R&D Annual Progress Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

The Propulsion Materials Program actively supports the energy security and reduction of greenhouse emissions goals of VTO by investigating and identifying the materials properties that are most essential for continued development of cost-effective, highly efficient, and environmentally friendly next-generation heavy and light-duty powertrains. The technical approaches available to enhance propulsion systems focus on improvements in both vehicle efficiency and fuel substitution, both of which must overcome the performance limitations of the materials currently in use. Propulsion Materials Program activities work with national laboratories, industry experts, and VTO powertrain systems (e.g., Advanced Combustion Engines [ACE], Advanced Power Electronics and Electrical Machinesmore » [APEEM], and fuels) teams to develop strategies that overcome materials limitations in future powertrain performance. The technical maturity of the portfolio of funded projects ranges from basic science to subsystem prototype validation. Projects within a Propulsion Materials Program activity address materials concerns that directly impact critical technology barriers within each of the above programs, including barriers that impact fuel efficiency, thermal management, emissions reduction, improved reliability, and reduced manufacturing costs. The program engages only the barriers that result from material property limitations and represent fundamental, high-risk materials issues.« less

FY2015 Propulsion Materials Annual Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

The Propulsion Materials Program actively supports the energy security and reduction of greenhouse emissions goals of VTO by investigating and identifying the materials properties that are most essential for continued development of cost-effective, highly efficient, and environmentally friendly next-generation heavy and light-duty powertrains. The technical approaches available to enhance propulsion systems focus on improvements in both vehicle efficiency and fuel substitution, both of which must overcome the performance limitations of the materials currently in use. Propulsion Materials Program activities work with national laboratories, industry experts, and VTO powertrain systems (e.g., Advanced Combustion Engines [ACE], Advanced Power Electronics and Electrical Machinesmore » [APEEM], and fuels) teams to develop strategies that overcome materials limitations in future powertrain performance. The technical maturity of the portfolio of funded projects ranges from basic science to subsystem prototype validation. Projects within a Propulsion Materials Program activity address materials concerns that directly impact critical technology barriers within each of the above programs, including barriers that impact fuel efficiency, thermal management, emissions reduction, improved reliability, and reduced manufacturing costs. The program engages only the barriers that result from material property limitations and represent fundamental, high-risk materials issues.« less

Barriers to performing stretching exercises among Korean-Chinese female migrant workers in Korea.

PubMed

Lee, Hyeonkyeong; Wilbur, JoEllen; Chae, Duckhee; Lee, Kyongeun; Lee, Meenhye

2015-01-01

The purpose of this study was to investigate the barriers to performing stretching exercise experienced by Korean-Chinese female migrant workers during a community-based 12-week stretching exercise intervention trial. Qualitative secondary data analysis was conducted using telephone counseling interview transcripts from 27 middle-aged, Korean-Chinese migrant women workers. A semistructured interview question asking barriers to performing stretching exercise was given to women who did not adhere to recommended stretching exercise. During the 12-week home-based stretching exercise intervention trial, six telephone calls were made to participants biweekly to elicit barriers to performing stretching exercise. Directed content analysis approach was utilized using three barrier categories: intrapersonal, interpersonal, and work-related environmental factors based on the ecological model. Participants experienced an average of 2.5 barriers during the study period. Intrapersonal barriers included lack of time and lack of motivation, and interpersonal barriers included no family to provide support and also a feeling resistance from coworkers. Work-related environmental barriers included frequent job changes, long working hours, lack of rest time, and unpredictable job demands. The findings highlight that migrant workers in Korea face unique work-related difficulties which present barriers to exercise. © 2014 Wiley Periodicals, Inc.

Barriers to Liposomal Gene Delivery: from Application Site to the Target.

PubMed

Saffari, Mostafa; Moghimi, Hamid Reza; Dass, Crispin R

2016-01-01

Gene therapy is a therapeutic approach to deliver genetic material into cells to alter their function in entire organism. One promising form of gene delivery system (DDS) is liposomes. The success of liposome-mediated gene delivery is a multifactorial issue and well-designed liposomal systems might lead to optimized gene transfection particularly in vivo. Liposomal gene delivery systems face different barriers from their site of application to their target, which is inside the cells. These barriers include presystemic obstacles (epithelial barriers), systemic barriers in blood circulation and cellular barriers. Epithelial barriers differ depending on the route of administration. Systemic barriers include enzymatic degradation, binding and opsonisation. Both of these barriers can act as limiting hurdles that genetic material and their vector should overcome before reaching the cells. Finally liposomes should overcome cellular barriers that include cell entrance, endosomal escape and nuclear uptake. These barriers and their impact on liposomal gene delivery will be discussed in this review.

Predicting drug penetration across the blood-brain barrier: comparison of micellar liquid chromatography and immobilized artificial membrane liquid chromatography.

PubMed

De Vrieze, Mike; Lynen, Frédéric; Chen, Kai; Szucs, Roman; Sandra, Pat

2013-07-01

Several in vitro methods have been tested for their ability to predict drug penetration across the blood-brain barrier (BBB) into the central nervous system (CNS). In this article, the performance of a variety of micellar liquid chromatographic (MLC) methods and immobilized artificial membrane (IAM) liquid chromatographic approaches were compared for a set of 45 solutes. MLC measurements were performed on a C18 column with sodium dodecyl sulfate (SDS), polyoxyethylene (23) lauryl ether (Brij35), or sodium deoxycholate (SDC) as surfactant in the micellar mobile phase. IAM liquid chromatography measurements were performed with Dulbecco's phosphate-buffered saline (DPBS) and methanol as organic modifier in the mobile phase. The corresponding retention and computed descriptor data for each solute were used for construction of models to predict transport across the blood-brain barrier (log BB). All data were correlated with experimental log BB values and the relative performance of the models was studied. SDS-based models proved most suitable for prediction of log BB values, followed closely by a simplified IAM method, in which it could be observed that extrapolation of retention data to 0% modifier in the mobile phase was unnecessary.

Performing a local barrier operation

DOEpatents

Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

2014-03-04

Performing a local barrier operation with parallel tasks executing on a compute node including, for each task: retrieving a present value of a counter; calculating, in dependence upon the present value of the counter and a total number of tasks performing the local barrier operation, a base value, the base value representing the counter's value prior to any task joining the local barrier; calculating, in dependence upon the base value and the total number of tasks performing the local barrier operation, a target value of the counter, the target value representing the counter's value when all tasks have joined the local barrier; joining the local barrier, including atomically incrementing the value of the counter; and repetitively, until the present value of the counter is no less than the target value of the counter: retrieving the present value of the counter and determining whether the present value equals the target value.

Performing a local barrier operation

DOEpatents

Archer, Charles J; Blocksome, Michael A; Ratterman, Joseph D; Smith, Brian E

2014-03-04

Performing a local barrier operation with parallel tasks executing on a compute node including, for each task: retrieving a present value of a counter; calculating, in dependence upon the present value of the counter and a total number of tasks performing the local barrier operation, a base value of the counter, the base value representing the counter's value prior to any task joining the local barrier; calculating, in dependence upon the base value and the total number of tasks performing the local barrier operation, a target value, the target value representing the counter's value when all tasks have joined the local barrier; joining the local barrier, including atomically incrementing the value of the counter; and repetitively, until the present value of the counter is no less than the target value of the counter: retrieving the present value of the counter and determining whether the present value equals the target value.

Assisting allied health in performance evaluation: a systematic review.

PubMed

Lizarondo, Lucylynn; Grimmer, Karen; Kumar, Saravana

2014-11-14

Performance evaluation raises several challenges to allied health practitioners and there is no agreed approach to measuring or monitoring allied health service performance. The aim of this review was to examine the literature on performance evaluation in healthcare to assist in the establishment of a framework that can guide the measurement and evaluation of allied health clinical service performance. This review determined the core elements of a performance evaluation system, tools for evaluating performance, and barriers to the implementation of performance evaluation. A systematic review of the literature was undertaken. Five electronic databases were used to search for relevant articles: MEDLINE, Embase, CINAHL, PsychInfo, and Academic Search Premier. Articles which focussed on any allied health performance evaluation or those which examined performance in health care in general were considered in the review. Content analysis was used to synthesise the findings from individual articles. A total of 37 articles were included in the review. The literature suggests there are core elements involved in performance evaluation which include prioritising clinical areas for measurement, setting goals, selecting performance measures, identifying sources of feedback, undertaking performance measurement, and reporting the results to relevant stakeholders. The literature describes performance evaluation as multi-dimensional, requiring information or data from more than one perspective to provide a rich assessment of performance. A range of tools or instruments are available to capture various perspectives and gather a comprehensive picture of health care quality. Every allied health care delivery system has different performance needs and will therefore require different approaches. However, there are core processes that can be used as a framework to evaluate allied health performance. A careful examination of barriers to performance evaluation and subsequent tailoring of strategies to overcome these barriers should be undertaken to achieve the aims of performance evaluation. The findings of this review should inform the development of a standardised framework that can be used to measure and evaluate allied health performance. Future research should explore the utility and overall impact of such framework in allied health service delivery.

Neutron and gamma (density) logging in welded tuff

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, W

This Technical Implementation Procedure (TIP) describes the field operation, and the management of data records pertaining to neutron logging and density logging in welded tuff. This procedure applies to all borehole surveys performed in support of Engineered Barrier System Field Tests (EBSFT), including the Earge Block Tests (LBT) and Initial Engineered Barrier System Field Tests (IEBSFT) - WBS 1.2.3.12.4. The purpose of this TIP is to provide guidelines so that other equally trained and qualified personnel can understand how the work is performed or how to repeat the work if needed. The work will be documented by the use ofmore » Scientific Notebooks (SNs) as discussed in 033-YMP-QP 3.4. The TIP will provide a set of guidelines which the scientists will take into account in conducting the mea- surements. The use of this TIP does not imply that this is repetitive work that does not require profes- sional judgment.« less

Clinical Consultation Systems: Designing for the Physician as Computer User

PubMed Central

Shortliffe, Edward H.

1981-01-01

The barriers to successful implementation of consultation systems for physicians have been frequently discussed. Our research has been directed at the development of computer techniques that will heighten the acceptance of high performance decision making tools. We discuss two current projects at Stanford Medical School that address both practical and theoretical issues in the design and construction of clinically useful systems.

Exploring Barriers of the Health System to Rehabilitation Services for People with Disabilities in Iran: A Qualitative Study

PubMed Central

Abdi, Kianoush; Arab, Mohammad; Rashidian, Arash; Kamali, Mohammad; Khankeh, Hamid Reza; Farahani, Farideh Khalajabadi

2015-01-01

Introduction The United Nations (UN) identified health as a basic human right, but, unfortunately, the evidence shows that people with disabilities (PWD) often have lower levels of health than the general population. This can be associated with problems in access to the services and programs. The aim of this study was to explore barriers of the health system to rehabilitation services for PWD in Iran. Methods This was a qualitative study conducted on 21 participants using semi-structured, in-depth interviews and content analysis from June 2014 to July 2015. Data analysis was performed by MAXQDA version 10. Results “Barriers” were the most prominent challenge of people with disabilities that needed access to rehabilitation services. These barriers were categorized into eight concepts of deficiency in the system that provides rehabilitation services, defect of education, deficiency in detecting and screening of people with disability, defect of stewardship in rehabilitation, ignoring socio-cultural factors, accessibility hardships, lack of identification, and financial hardships in rehabilitation. Conclusions An efficient rehabilitation plan requires a common understanding, considering the long-term complications involved in addressing the barriers. Understanding the barriers of the health system to rehabilitation services requires comprehensive management that first should be familiar with all of PWD, providers, policy makers, and other beneficiaries. It also is necessary for policy makers to consider rehabilitation services as a main part of the health plan; especially, they must change their oversight of rehabilitation services and programs. Thus, policy makers should have need comprehensive management and recommended further research. PMID:26767101

Effects of compositional changes on the performance of a thermal barrier coating system. [for aircraft gas turbine engines

NASA Technical Reports Server (NTRS)

Stecura, S.

1979-01-01

Systems consisting of Ni-base bond coatings containing about 16Cr, 6Al, and from 0.15 to 1.08Y (all in wt %) and zirconium oxide layers containing from 4.0 to 24.4Y2O3 were evaluated for suitability as thermal barrier systems for advanced aircraft gas turbine engine components. The evaluations were performed in a cyclic furnace between 990 and 280 C as well as between 1095 and 280 C on solid specimens; in a natural gas-oxygen torch rig between about 1200 and 100 C on solid specimens and up to 1580 C surface temperatures on air-cooled blades; and in a Mach 1.0 burner rig up to 1570 C surface temperatures on air-cooled blades. The data indicate that the best systems consist of combinations involving the Ni-16.4Cr-5.1Al-0.15Y and Ni-17.0Cr-5.4Al-0.35Y bond coatings and the 6.2Y2O3- and 7.9Y2O3- (all in wt %) stabilized zirconium oxide layers.

A cluster expansion model for predicting activation barrier of atomic processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rehman, Tafizur; Jaipal, M.; Chatterjee, Abhijit, E-mail: achatter@iitk.ac.in

2013-06-15

We introduce a procedure based on cluster expansion models for predicting the activation barrier of atomic processes encountered while studying the dynamics of a material system using the kinetic Monte Carlo (KMC) method. Starting with an interatomic potential description, a mathematical derivation is presented to show that the local environment dependence of the activation barrier can be captured using cluster interaction models. Next, we develop a systematic procedure for training the cluster interaction model on-the-fly, which involves: (i) obtaining activation barriers for handful local environments using nudged elastic band (NEB) calculations, (ii) identifying the local environment by analyzing the NEBmore » results, and (iii) estimating the cluster interaction model parameters from the activation barrier data. Once a cluster expansion model has been trained, it is used to predict activation barriers without requiring any additional NEB calculations. Numerical studies are performed to validate the cluster expansion model by studying hop processes in Ag/Ag(100). We show that the use of cluster expansion model with KMC enables efficient generation of an accurate process rate catalog.« less

Development and Property Evaluation of Selected HfO2-Silicon and Rare Earth-Silicon Based Bond Coats and Environmental Barrier Coating Systems for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming

2016-01-01

Ceramic environmental barrier coatings (EBC) and SiC/SiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft propulsion systems because of their ability to significantly increase engine operating temperatures, improve component durability, reduce engine weight and cooling requirements. Advanced EBC systems for SiC/SiC CMC turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant material development challenges for the high temperature CMC components is to develop prime-reliant, high strength and high temperature capable environmental barrier coating bond coat systems, since the current silicon bond coat cannot meet the advanced EBC-CMC temperature and stability requirements. In this paper, advanced NASA HfO2-Si and rare earth Si based EBC bond coat EBC systems for SiC/SiC CMC combustor and turbine airfoil applications are investigated. High temperature properties of the advanced EBC systems, including the strength, fracture toughness, creep and oxidation resistance have been studied and summarized. The advanced NASA EBC systems showed some promise to achieve 1500C temperature capability, helping enable next generation turbine engines with significantly improved engine component temperature capability and durability.

Overview of thermal barrier coatings in diesel engines

NASA Technical Reports Server (NTRS)

Yonushonis, Thomas M.

1995-01-01

An understanding of delamination mechanisms in thermal barrier coatings has been developed for diesel engine applications through rig tests, structural analysis modeling, nondestructive evaluation, and engine evaluation of various thermal barrier coatings. This knowledge has resulted in improved thermal barrier coatings which survive abusive cyclic fatigue tests in high output diesel engines. Although much conflicting literature now exists regarding the impact of thermal barrier coatings on engine performance and fuel consumption, the changes in fuel consumption appear to be less than a few percent and can be negative for state-of-the-art diesel engines. The ability of the thermal barrier coating to improve fuel economy tends to be dependent on a number of factors including the fuel injection system, combustion chamber design, and the initial engine fuel economy. Limited investigations on state-of-the-art diesel engines have indicated that the surface connected porosity and coating surface roughness may influence engine fuel economy. Current research efforts on thermal barrier coatings are primarily directed at reducing in-cylinder heat rejection, thermal fatigue protection of underlying metal surfaces and a possible reduction in diesel engine emissions. Significant efforts are still required to improve the plasma spray processing capability and the economics for complex geometry diesel engine components.

System-Level Action Required for Wide-Scale Improvement in Quality of Primary Health Care: Synthesis of Feedback from an Interactive Process to Promote Dissemination and Use of Aggregated Quality of Care Data.

PubMed

Bailie, Jodie; Laycock, Alison; Matthews, Veronica; Bailie, Ross

2016-01-01

There is an enduring gap between recommended practice and care that is actually delivered; and there is wide variation between primary health care (PHC) centers in delivery of care. Where aspects of care are not being done well across a range of PHC centers, this is likely due to inadequacies in the broader system. This paper aims to describe stakeholders' perceptions of the barriers and enablers to addressing gaps in Australian Aboriginal and Torres Strait Islander chronic illness care and child health, and to identify key drivers for improvement. This paper draws on data collected as part of a large-scale continuous quality improvement project in Australian Indigenous PHC settings. We undertook a qualitative assessment of stakeholder feedback on the main barriers and enablers to addressing gaps in care for Aboriginal and Torres Strait Islander children and in chronic illness care. Themes on barriers and enablers were further analyzed to develop a "driver diagram," an improvement tool used to locate barriers and enablers within causal pathways (as primary and secondary drivers), enabling them to be targeted by tailored interventions. We identified 5 primary drivers and 11 secondary drivers of high-quality care, and associated strategies that have potential for wide-scale implementation to address barriers and enablers for improving care. Perceived barriers to addressing gaps in care included both health system and staff attributes. Primary drivers were: staff capability to deliver high-quality care; availability and use of clinical information systems and decision support tools; embedding of quality improvement processes and data-driven decision-making; appropriate and effective recruitment and retention of staff; and community capacity, engagement and mobilization for health. Suggested strategies included mechanisms for increasing clinical supervision and support, staff retention, reorientation of service delivery, use of information systems and community health literacy. The findings identify areas of focus for development of barrier-driven, tailored interventions to improve health outcomes. They reinforce the importance of system-level action to improve health center performance and health outcomes, and of developing strategies to address system-wide challenges that can be adapted to local contexts.

Design and performance evaluation of a 1000-year evapotranspiration-capillary surface barrier.

PubMed

Zhang, Zhuanfang Fred; Strickland, Christopher E; Link, Steven O

2017-02-01

Surface barrier technology is used to isolate radioactive waste and to reduce or eliminate recharge water to the waste zone for 1000 years or longer. However, the design and evaluation of such a barrier is challenging because of the extremely long design life. After establishing a set of design and performance objectives, a package of design solutions was developed for 1000-year surface barriers over nuclear waste sites. The Prototype Hanford Barrier (PHB) was then constructed in 1994 in the field over an existing waste site as a demonstration. The barrier was tested to evaluate surface-barrier design and performance at the field scale under conditions of enhanced and natural precipitation and of no vegetation. The monitoring data demonstrate that the barrier satisfied nearly all objectives in the past two decades. The PHB far exceeded the Resource Conservation and Recovery Act criteria, functioned in Hanford's semiarid climate, limited drainage to well below the 0.5 mm yr -1 performance criterion, limited runoff, and minimized erosion and bio-intrusion. Given the two-decade record of successful performance and consideration of the processes and mechanisms that could affect barrier stability and hydrology in the future, the results suggest the PHB is very likely to perform for its 1000-year design life. This conclusion is based on two assumptions: (1) the exposed subgrade receives protection against erosion and (2) institutional controls prevent inadvertent human activity at the barrier. The PHB design can serve as the basis for site-specific barriers over waste sites containing underground nuclear waste, uranium mine tailings, and hazardous mine waste. Copyright © 2016 Elsevier Ltd. All rights reserved.

Functions of an engineered barrier system for a nuclear waste repository in basalt

NASA Astrophysics Data System (ADS)

Coons, W. E.; Moore, E. L.; Smith, M. J.; Kaser, J. D.

1980-01-01

The functions of components selected for an engineered barrier system for a nuclear waste repository in basalt are defined providing a focal point for barrier material research and development by delineating the purpose and operative lifetime of each component of the engineered system. A five component system (comprised of waste form, canister, buffer, overpack, and tailored backfill) is discussed. Redundancy is provided by subsystems of physical and chemical barriers which act in concert with the geology to provide a formidable barrier to transport of hazardous materials to the biosphere. The barrier system is clarified by examples pertinent to storage in basalt, and a technical approach to barrier design and material selection is proposed.

Systems thinking in practice: the current status of the six WHO building blocks for health system strengthening in three BHOMA intervention districts of Zambia: a baseline qualitative study.

PubMed

Mutale, Wilbroad; Bond, Virginia; Mwanamwenge, Margaret Tembo; Mlewa, Susan; Balabanova, Dina; Spicer, Neil; Ayles, Helen

2013-08-01

The primary bottleneck to achieving the MDGs in low-income countries is health systems that are too fragile to deliver the volume and quality of services to those in need. Strong and effective health systems are increasingly considered a prerequisite to reducing the disease burden and to achieving the health MDGs. Zambia is one of the countries that are lagging behind in achieving millennium development targets. Several barriers have been identified as hindering the progress towards health related millennium development goals. Designing an intervention that addresses these barriers was crucial and so the Better Health Outcomes through Mentorship (BHOMA) project was designed to address the challenges in the Zambia's MOH using a system wide approach. We applied systems thinking approach to describe the baseline status of the Six WHO building blocks for health system strengthening. A qualitative study was conducted looking at the status of the Six WHO building blocks for health systems strengthening in three BHOMA districts. We conducted Focus group discussions with community members and In-depth Interviews with key informants. Data was analyzed using Nvivo version 9. The study showed that building block specific weaknesses had cross cutting effect in other health system building blocks which is an essential element of systems thinking. Challenges noted in service delivery were linked to human resources, medical supplies, information flow, governance and finance building blocks either directly or indirectly. Several barriers were identified as hindering access to health services by the local communities. These included supply side barriers: Shortage of qualified health workers, bad staff attitude, poor relationships between community and health staff, long waiting time, confidentiality and the gender of health workers. Demand side barriers: Long distance to health facility, cost of transport and cultural practices. Participating communities seemed to lack the capacity to hold health workers accountable for the drugs and services. The study has shown that building block specific weaknesses had cross cutting effect in other health system building blocks. These linkages emphasised the need to use system wide approaches in assessing the performance of health system strengthening interventions.

Moisture and Structural Analysis for High Performance Hybrid Wall Assemblies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grin, A.; Lstiburek, J.

2012-09-01

Based on past experience in the Building America program, BSC has found that combinations of materials and approaches—in other words, systems—usually provide optimum performance. Integration is necessary, as described in this research project. The hybrid walls analyzed utilize a combination of exterior insulation, diagonal metal strapping, and spray polyurethane foam and leave room for cavity-fill insulation. These systems can provide effective thermal, air, moisture, and water barrier systems in one assembly and provide structure.

Thermal Cyclic Behavior of Thermal and Environmental Barrier Coatings Investigated Under High-Heat-Flux Conditions

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Lee, Kang N.; Miller, Robert A.

2002-01-01

Environmental barrier coatings (EBC's) have been developed to protect silicon-carbide- (SiC) based ceramic components in gas turbine engines from high-temperature environmental attack. With continuously increasing demands for significantly higher engine operating temperature, future EBC systems must be designed for both thermal and environmental protection of the engine components in combustion gases. In particular, the thermal barrier functions of EBC's become a necessity for reducing the engine-component thermal loads and chemical reaction rates, thus maintaining the required mechanical properties and durability of these components. Advances in the development of thermal and environmental barrier coatings (TBC's and EBC's, respectively) will directly impact the successful use of ceramic components in advanced engines. To develop high-performance coating systems, researchers must establish advanced test approaches. In this study, a laser high-heat-flux technique was employed to investigate the thermal cyclic behavior of TBC's and EBC's on SiC-reinforced SiC ceramic matrix composite substrates (SiC/SiC) under high thermal gradient and thermal cycling conditions. Because the laser heat flux test approach can monitor the coating's real-time thermal conductivity variations at high temperature, the coating thermal insulation performance, sintering, and delamination can all be obtained during thermal cycling tests. Plasma-sprayed yttria-stabilized zirconia (ZrO2-8 wt% Y2O3) thermal barrier and barium strontium aluminosilicate-based environmental barrier coatings (BSAS/BSAS+mullite/Si) on SiC/SiC ceramic matrix composites were investigated in this study. These coatings were laser tested in air under thermal gradients (the surface and interface temperatures were approximately 1482 and 1300 C, respectively). Some coating specimens were also subject to alternating furnace cycling (in a 90-percent water vapor environment at 1300 C) and laser thermal gradient cycling tests (in air), to investigate the water vapor effect. All cyclic tests were conducted using a 60-min hot-time temperature.

Examining empirical evidence of the effect of superfluidity on the fusion barrier

NASA Astrophysics Data System (ADS)

Scamps, Guillaume

2018-04-01

Background: Recent time-dependent Hartree-Fock-Bogoliubov (TDHFB) calculations predict that superfluidity enhances fluctuations of the fusion barrier. This effect is not fully understood and not yet experimentally revealed. Purpose: The goal of this study is to empirically investigate the effect of superfluidity on the distribution width of the fusion barrier. Method: Two new methods are proposed in the present study. First, the local regression method is introduced and used to determine the barrier distribution. The second method, which requires only the calculation of an integral of the cross section, is developed to determine accurately the fluctuations of the barrier. This integral method, showing the best performance, is systematically applied to 115 fusion reactions. Results: Fluctuations of the barrier for open-shell systems are, on average, larger than those for magic or semimagic nuclei. This is due to the deformation and the superfluidity. To disentangle these two effects, a comparison is made between the experimental width and the width estimated from a model that takes into account the tunneling, the deformation, and the vibration effect. This study reveals that superfluidity enhances the fusion barrier width. Conclusions: This analysis shows that the predicted effect of superfluidity on the width of the barrier is real and is of the order of 1 MeV.

Efficient free energy calculations by combining two complementary tempering sampling methods.

PubMed

Xie, Liangxu; Shen, Lin; Chen, Zhe-Ning; Yang, Mingjun

2017-01-14

Although energy barriers can be efficiently crossed in the reaction coordinate (RC) guided sampling, this type of method suffers from identification of the correct RCs or requirements of high dimensionality of the defined RCs for a given system. If only the approximate RCs with significant barriers are used in the simulations, hidden energy barriers with small to medium height would exist in other degrees of freedom (DOFs) relevant to the target process and consequently cause the problem of insufficient sampling. To address the sampling in this so-called hidden barrier situation, here we propose an effective approach to combine temperature accelerated molecular dynamics (TAMD), an efficient RC-guided sampling method, with the integrated tempering sampling (ITS), a generalized ensemble sampling method. In this combined ITS-TAMD method, the sampling along the major RCs with high energy barriers is guided by TAMD and the sampling of the rest of the DOFs with lower but not negligible barriers is enhanced by ITS. The performance of ITS-TAMD to three systems in the processes with hidden barriers has been examined. In comparison to the standalone TAMD or ITS approach, the present hybrid method shows three main improvements. (1) Sampling efficiency can be improved at least five times even if in the presence of hidden energy barriers. (2) The canonical distribution can be more accurately recovered, from which the thermodynamic properties along other collective variables can be computed correctly. (3) The robustness of the selection of major RCs suggests that the dimensionality of necessary RCs can be reduced. Our work shows more potential applications of the ITS-TAMD method as the efficient and powerful tool for the investigation of a broad range of interesting cases.

Efficient free energy calculations by combining two complementary tempering sampling methods

NASA Astrophysics Data System (ADS)

Xie, Liangxu; Shen, Lin; Chen, Zhe-Ning; Yang, Mingjun

2017-01-01

Although energy barriers can be efficiently crossed in the reaction coordinate (RC) guided sampling, this type of method suffers from identification of the correct RCs or requirements of high dimensionality of the defined RCs for a given system. If only the approximate RCs with significant barriers are used in the simulations, hidden energy barriers with small to medium height would exist in other degrees of freedom (DOFs) relevant to the target process and consequently cause the problem of insufficient sampling. To address the sampling in this so-called hidden barrier situation, here we propose an effective approach to combine temperature accelerated molecular dynamics (TAMD), an efficient RC-guided sampling method, with the integrated tempering sampling (ITS), a generalized ensemble sampling method. In this combined ITS-TAMD method, the sampling along the major RCs with high energy barriers is guided by TAMD and the sampling of the rest of the DOFs with lower but not negligible barriers is enhanced by ITS. The performance of ITS-TAMD to three systems in the processes with hidden barriers has been examined. In comparison to the standalone TAMD or ITS approach, the present hybrid method shows three main improvements. (1) Sampling efficiency can be improved at least five times even if in the presence of hidden energy barriers. (2) The canonical distribution can be more accurately recovered, from which the thermodynamic properties along other collective variables can be computed correctly. (3) The robustness of the selection of major RCs suggests that the dimensionality of necessary RCs can be reduced. Our work shows more potential applications of the ITS-TAMD method as the efficient and powerful tool for the investigation of a broad range of interesting cases.

49 CFR 587.3 - Application.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Other Regulations Relating to Transportation (Continued) NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) DEFORMABLE BARRIERS General § 587.3 Application. This part does not... compliance tests to measure the performance of occupant protection systems required by the safety standards...

Reduction and Immobilization of Radionuclides and Toxic Metal Ions Using Combined Zero Valent Iron and Anaerobic Bacteria

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lenly J. Weathers; Lynn E. Katz

2002-05-29

The use of zero valent iron, permeable reactive barriers (PRBs) for groundwater remediation continues to increase. AN exciting variation of this technology involves introducing anaerobic bacteria into these barriers so that both biological and abiotic pollutant removal processes are functional. This work evaluated the hypothesis that a system combining a mixed culture of sulfate reducing bacteria (SRB) with zero valent iron would have a greater cr(VI) removal efficiency and a greater total Cr(VI) removal capacity than a zero valent iron system without the microorganisms. Hence, the overall goal of this research was to compare the performance of these types ofmore » systems with regard to their Cr(VI) removal efficiency and total Cr(VI) removal capacity. Both batch and continuous flow reactor systems were evaluated.« less

Environmental Barrier Coating Fracture, Fatigue and High-Heat-Flux Durability Modeling and Stochastic Progressive Damage Simulation

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Nemeth, Noel N.

2017-01-01

Advanced environmental barrier coatings will play an increasingly important role in future gas turbine engines because of their ability to protect emerging light-weight SiC/SiC ceramic matrix composite (CMC) engine components, further raising engine operating temperatures and performance. Because the environmental barrier coating systems are critical to the performance, reliability and durability of these hot-section ceramic engine components, a prime-reliant coating system along with established life design methodology are required for the hot-section ceramic component insertion into engine service. In this paper, we have first summarized some observations of high temperature, high-heat-flux environmental degradation and failure mechanisms of environmental barrier coating systems in laboratory simulated engine environment tests. In particular, the coating surface cracking morphologies and associated subsequent delamination mechanisms under the engine level high-heat-flux, combustion steam, and mechanical creep and fatigue loading conditions will be discussed. The EBC compostion and archtechture improvements based on advanced high heat flux environmental testing, and the modeling advances based on the integrated Finite Element Analysis Micromechanics Analysis Code/Ceramics Analysis and Reliability Evaluation of Structures (FEAMAC/CARES) program will also be highlighted. The stochastic progressive damage simulation successfully predicts mud flat damage pattern in EBCs on coated 3-D specimens, and a 2-D model of through-the-thickness cross-section. A 2-parameter Weibull distribution was assumed in characterizing the coating layer stochastic strength response and the formation of damage was therefore modeled. The damage initiation and coalescence into progressively smaller mudflat crack cells was demonstrated. A coating life prediction framework may be realized by examining the surface crack initiation and delamination propagation in conjunction with environmental degradation under high-heat-flux and environment load test conditions.

Design and performance evaluation of a 1000-year evapotranspiration-capillary surface barrier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Zhuanfang Fred; Strickland, Christopher E.; Link, Steven O.

Surface barrier technology is used to isolate radioactive waste and to reduce or eliminate recharge water to the waste zone for 1000 years or longer. However, the design and evaluation of such a barrier is challenging because of the extremely long design life. The Prototype Hanford Barrier (PHB) was designed as a 1000-year barrier with pre-determined design and performance objectives and demonstrated in field from 1994 to present. The barrier was tested to evaluate surface-barrier design and performance at the field scale under conditions of enhanced and natural precipitation and of no vegetation. The monitoring data demonstrate that the barriermore » satisfied nearly all key objectives. The PHB far exceeded the Resource Conservation and Recovery Act criteria, functioned in Hanford’s semiarid climate, limited drainage to well below the 0.5 mm yr-1 performance criterion, limited runoff, and minimized erosion. Given the two-decade record of successful performance and consideration of all the processes and mechanisms that could degrade the stability and hydrology in the future, the results suggest the PHB is very likely to perform for its 1000-year design life. This conclusion is based on two assumptions: (1) the exposed subgrade receives protection against erosion and (2) institutional controls prevent inadvertent human activity at the barrier. The PHB design can serve as the base for site-specific barriers over waste sites containing underground nuclear waste, uranium mine tailings, and hazardous mine waste.« less

Distributed Optimal Consensus Over Resource Allocation Network and Its Application to Dynamical Economic Dispatch.

PubMed

Li, Chaojie; Yu, Xinghuo; Huang, Tingwen; He, Xing; Chaojie Li; Xinghuo Yu; Tingwen Huang; Xing He; Li, Chaojie; Huang, Tingwen; He, Xing; Yu, Xinghuo

2018-06-01

The resource allocation problem is studied and reformulated by a distributed interior point method via a -logarithmic barrier. By the facilitation of the graph Laplacian, a fully distributed continuous-time multiagent system is developed for solving the problem. Specifically, to avoid high singularity of the -logarithmic barrier at boundary, an adaptive parameter switching strategy is introduced into this dynamical multiagent system. The convergence rate of the distributed algorithm is obtained. Moreover, a novel distributed primal-dual dynamical multiagent system is designed in a smart grid scenario to seek the saddle point of dynamical economic dispatch, which coincides with the optimal solution. The dual decomposition technique is applied to transform the optimization problem into easily solvable resource allocation subproblems with local inequality constraints. The good performance of the new dynamical systems is, respectively, verified by a numerical example and the IEEE six-bus test system-based simulations.

PERSON-Personalized Expert Recommendation System for Optimized Nutrition.

PubMed

Chen, Chih-Han; Karvela, Maria; Sohbati, Mohammadreza; Shinawatra, Thaksin; Toumazou, Christofer

2018-02-01

The rise of personalized diets is due to the emergence of nutrigenetics and genetic tests services. However, the recommendation system is far from mature to provide personalized food suggestion to consumers for daily usage. The main barrier of connecting genetic information to personalized diets is the complexity of data and the scalability of the applied systems. Aiming to cross such barriers and provide direct applications, a personalized expert recommendation system for optimized nutrition is introduced in this paper, which performs direct to consumer personalized grocery product filtering and recommendation. Deep learning neural network model is applied to achieve automatic product categorization. The ability of scaling with unknown new data is achieved through the generalized representation of word embedding. Furthermore, the categorized products are filtered with a model based on individual genetic data with associated phenotypic information and a case study with databases from three different sources is carried out to confirm the system.

Barriers and enablers of health system adoption of kangaroo mother care: a systematic review of caregiver perspectives.

PubMed

Smith, Emily R; Bergelson, Ilana; Constantian, Stacie; Valsangkar, Bina; Chan, Grace J

2017-01-25

Despite improvements in child survival in the past four decades, an estimated 6.3 million children under the age of five die each year, and more than 40% of these deaths occur in the neonatal period. Interventions to reduce neonatal mortality are needed. Kangaroo mother care (KMC) is one such life-saving intervention; however it has not yet been fully integrated into health systems around the world. Utilizing a conceptual framework for integration of targeted health interventions into health systems, we hypothesize that caregivers play a critical role in the adoption, diffusion, and assimilation of KMC. The objective of this research was to identify barriers and enablers of implementation and scale up of KMC from caregivers' perspective. We searched Pubmed, Embase, Web of Science, Scopus, and WHO regional databases using search terms 'kangaroo mother care' or 'kangaroo care' or 'skin to skin care'. Studies published between January 1, 1960 and August 19, 2015 were included. To be eligible, published work had to be based on primary data collection regarding barriers or enablers of KMC implementation from the family perspective. Abstracted data were linked to the conceptual framework using a deductive approach, and themes were identified within each of the five framework areas using Nvivo software. We identified a total of 2875 abstracts. After removing duplicates and ineligible studies, 98 were included in the analysis. The majority of publications were published within the past 5 years, had a sample size less than 50, and recruited participants from health facilities. Approximately one-third of the studies were conducted in the Americas, and 26.5% were conducted in Africa. We identified four themes surrounding the interaction between families and the KMC intervention: buy in and bonding (i.e. benefits of KMC to mothers and infants and perceptions of bonding between mother and infant), social support (i.e. assistance from other people to perform KMC), sufficient time to perform KMC, and medical concerns about mother or newborn health. Furthermore, we identified barriers and enablers of KMC adoption by caregivers within the context of the health system regarding financing and service delivery. Embedded within the broad social context, barriers to KMC adoption by caregivers included adherence to traditional newborn practices, stigma surrounding having a preterm infant, and gender roles regarding childcare. Efforts to scale up and integrate KMC into health systems must reduce barriers in order to promote the uptake of the intervention by caregivers.

Three-dimensional visualization and display technologies; Proceedings of the Meeting, Los Angeles, CA, Jan. 18-20, 1989

NASA Technical Reports Server (NTRS)

Robbins, Woodrow E. (Editor); Fisher, Scott S. (Editor)

1989-01-01

Special attention was given to problems of stereoscopic display devices, such as CAD for enhancement of the design process in visual arts, stereo-TV improvement of remote manipulator performance, a voice-controlled stereographic video camera system, and head-mounted displays and their low-cost design alternatives. Also discussed was a novel approach to chromostereoscopic microscopy, computer-generated barrier-strip autostereography and lenticular stereograms, and parallax barrier three-dimensional TV. Additional topics include processing and user interface isssues and visualization applications, including automated analysis and fliud flow topology, optical tomographic measusrements of mixing fluids, visualization of complex data, visualization environments, and visualization management systems.

Evaluating the Longevity and Hydraulic Performance of Permeable Reactive Barriers at Department of Defense Sites

DTIC Science & Technology

2001-10-01

Draft Final Report Evaluating the Longevity and Hydraulic Performance of Permeable Reactive Barriers at Department of Defense Sites Prepared for...AND SUBTITLE Evaluating the Longevity and Hydraulic Performance of Permeable Reactive Barriers at Department of Defense Sites 5a. CONTRACT NUMBER...34 4.3.2 Hydraulic Performance Evaluation .................................................................... 38 4.3.2.1 Water-Level

Perceived barriers to effective job performance among nursing assistants in long-term care.

PubMed

Parmelee, Patricia A; Laszlo, Mary C; Taylor, Jo A

2009-10-01

This research explored perceived barriers to job performance among a national sample of nursing assistants (NAs). Specific objectives were (1) to clarify which of the problems identified by previous research are most troublesome for NAs, (2) to develop a reliable quantitative measure of perceived barriers to job performance, and (3) to test construct validity of the measure vis-à-vis work-related psychological empowerment and job satisfaction. Nursing assistants attending the 2006 national conference of the National Association of Health Care Assistants completed a paper-and-pencil survey including 33 barriers to job performance and standardized measures of empowerment and job satisfaction. The barriers were also rated by a small sample of NAs at a single Georgia nursing home. Factor analysis of barriers items yielded a 30-item Nursing Assistants Barriers Scale (NABS) comprising 6 subscales: Teamwork, Exclusion, Respect, Workload, Work Stress, and New NAs. Lack of teamwork and exclusion from communication processes were rated as most problematic by both samples. The 6 NABS subscales were significantly and independently associated with empowerment and satisfaction; different barriers predicted the 2 constructs. This study is a first step toward quantitative assessment of NAs' perceptions of barriers to doing their jobs. Primary limitations are the select sample and use of a job satisfaction measure that may have artificially inflated correlations with the NABS. Nonetheless, results confirm the validity of the new scale as an operationalization of the barriers construct. The concept of barriers to job performance is a unique construct from work empowerment and satisfaction with one's job. Nursing assistants clearly differentiate various barriers, converging on workload and lack of teamwork as most problematic. Further work is needed to substantiate validity and reliability of the NABS, particularly with respect to NAs' actual job performance, intent to stay on the job versus leave, absenteeism, and turnover.

Interfacial Chemistry-Induced Modulation of Schottky Barrier Heights: In Situ Measurements of the Pt-Amorphous Indium Gallium Zinc Oxide Interface Using X-ray Photoelectron Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flynn, Brendan T.; Oleksak, Richard P.; Thevuthasan, Suntharampillai

A method to modulate the Schottky barrier heights for platinum and amorphous indium gallium zinc oxide (a-IGZO) interfaces is demonstrated through thermal processing and background ambient pressure control. The interfacial chemistries that modulate barrier heights for the Pt/a-IGZO system were investigated using in-situ X-ray photoelectron spectroscopy. A significant reduction of indium, from In3+ to In0, occurs during deposition of Pt on to the a-IGZO surface in ultra-high vacuum. Post-annealing and controlling the background ambient O2 pressure allows tuning the degree of indium reduction and the corresponding Schottky barrier height between 0.17 to 0.77 eV. Understanding the detailed interfacial chemistries atmore » Pt/a-IGZO interfaces may allow for improved electronic device performance, including Schottky diodes, memristors, and metalsemiconductor field-effect transistors.« less

Monte Carlo Simulation of THz Multipliers

NASA Technical Reports Server (NTRS)

East, J.; Blakey, P.

1997-01-01

Schottky Barrier diode frequency multipliers are critical components in submillimeter and Thz space based earth observation systems. As the operating frequency of these multipliers has increased, the agreement between design predictions and experimental results has become poorer. The multiplier design is usually based on a nonlinear model using a form of harmonic balance and a model for the Schottky barrier diode. Conventional voltage dependent lumped element models do a poor job of predicting THz frequency performance. This paper will describe a large signal Monte Carlo simulation of Schottky barrier multipliers. The simulation is a time dependent particle field Monte Carlo simulation with ohmic and Schottky barrier boundary conditions included that has been combined with a fixed point solution for the nonlinear circuit interaction. The results in the paper will point out some important time constants in varactor operation and will describe the effects of current saturation and nonlinear resistances on multiplier operation.

Interfacial Chemistry-Induced Modulation of Schottky Barrier Heights: In Situ Measurements of the Pt–Amorphous Indium Gallium Zinc Oxide Interface Using X-ray Photoelectron Spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flynn, Brendan T.; Oleksak, Richard P.; Thevuthasan, Suntharampillai

A method to modulate the Schottky barrier heights for platinum and amorphous indium gallium zinc oxide (a-IGZO) interfaces is demonstrated through thermal processing and background ambient pressure control. The interfacial chemistries that modulate barrier heights for the Pt/a-IGZO system were investigated using in-situ X-ray photoelectron spectroscopy. A significant reduction of indium, from In 3+ to In 0, occurs during deposition of Pt on to the a-IGZO surface in ultra-high vacuum. Post-annealing and controlling the background ambient O 2 pressure allows tuning the degree of indium reduction and the corresponding Schottky barrier height between 0.17 to 0.77 eV. Understanding the detailedmore » interfacial chemistries at Pt/a-IGZO interfaces may allow for improved electronic device performance, including Schottky diodes, memristors, and metalsemiconductor field-effect transistors.« less

Degradation of organic pollutants and microorganisms from wastewater using different dielectric barrier discharge configurations--a critical review.

PubMed

Mouele, Emile S Massima; Tijani, Jimoh O; Fatoba, Ojo O; Petrik, Leslie F

2015-12-01

The growing global drinking water crisis requires the development of novel advanced, sustainable, and cost-effective water treatment technologies to supplement the existing conventional methods. One such technology is advanced oxidation based on dielectric barrier discharge (DBD). DBD such as single and double planar and single and double cylindrical dielectric barrier configurations have been utilized for efficient degradation of recalcitrant organic pollutants. The overall performance of the different DBD system varies and depends on several factors. Therefore, this review was compiled to give an overview of different DBD configurations vis-a-viz their applications and the in situ mechanism of generation of free reactive species for water and wastewater treatment. Our survey of the literature indicated that application of double cylindrical dielectric barrier configuration represents an ideal and viable route for achieving greater water and wastewater purification efficiency.

77 FR 39677 - Performance Review Board Membership

Federal Register 2010, 2011, 2012, 2013, 2014

2012-07-05

... ARCHITECTURAL AND TRANSPORTATION BARRIERS COMPLIANCE BOARD Performance Review Board Membership AGENCY: Architectural and Transportation Barriers Compliance Board. ACTION: Notice. SUMMARY: Notice is... Transportation Barriers Compliance Board (Access Board). FOR FURTHER INFORMATION CONTACT: David M. Capozzi...

The Development of HfO2-Rare Earth Based Oxide Materials and Barrier Coatings for Thermal Protection Systems

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan James

2014-01-01

Advanced hafnia-rare earth oxides, rare earth aluminates and silicates have been developed for thermal environmental barrier systems for aerospace propulsion engine and thermal protection applications. The high temperature stability, low thermal conductivity, excellent oxidation resistance and mechanical properties of these oxide material systems make them attractive and potentially viable for thermal protection systems. This paper will focus on the development of the high performance and high temperature capable ZrO2HfO2-rare earth based alloy and compound oxide materials, processed as protective coating systems using state-or-the-art processing techniques. The emphasis has been in particular placed on assessing their temperature capability, stability and suitability for advanced space vehicle entry thermal protection systems. Fundamental thermophysical and thermomechanical properties of the material systems have been investigated at high temperatures. Laser high-heat-flux testing has also been developed to validate the material systems, and demonstrating durability under space entry high heat flux conditions.

Evaluation of a movable concrete barrier system.

DOT National Transportation Integrated Search

1994-01-01

The movable concrete barrier (MCB) system consists of 1-m-long sections of barrier connected by steel pins in hinges to form a barrier wall that is moved laterally with a transport/transfer vehicle. The MCB system allows for the quick closing and ope...

Human Mission to Europa and Titan - Why Not? Executive Summary

NASA Technical Reports Server (NTRS)

Finarelli, Margaret G.

2005-01-01

Outline a step-by-step Development Plan of the key barriers and their solutions to enable human exploration of the outer solar system. Secondary: Perform a case study which supports and emphasizes the key elements of the Development Plan.

Evaluation of a mobile work zone barrier system : appendices.

DOT National Transportation Integrated Search

2013-08-01

A high percentage of highway maintenance activities and some construction activities are performed in a travel lane, median, or shoulder while the public travels by at relatively high speeds in very close proximity to the workers. Work zone traffic c...

Evaluation of a mobile work zone barrier system.

DOT National Transportation Integrated Search

2013-08-01

A high percentage of highway maintenance activities and some construction activities are performed in a travel lane, median, or shoulder while the public travels by at relatively high speeds in very close proximity to the workers. Work zone traffic c...

Using a Systems Engineering Initiative for Patient Safety to Evaluate a Hospital-wide Daily Chlorhexidine Bathing Intervention.

PubMed

Caya, Teresa; Musuuza, Jackson; Yanke, Eric; Schmitz, Michelle; Anderson, Brooke; Carayon, Pascale; Safdar, Nasia

2015-01-01

We undertook a systems engineering approach to evaluate housewide implementation of daily chlorhexidine bathing. We performed direct observations of the bathing process and conducted provider and patient surveys. The main outcome was compliance with bathing using a checklist. Fifty-seven percent of baths had full compliance with the chlorhexidine bathing protocol. Additional time was the main barrier. Institutions undertaking daily chlorhexidine bathing should perform a rigorous assessment of implementation to optimize the benefits of this intervention.

Exploring the influence of transfer channels on fusion reactions: The case of 40 Ca + 58,64 Ni

DOE PAGES

Bourgin, D.; Courtin, S.; Haas, F.; ...

2015-01-29

Fusion cross sections have been measured in the 40Ca + 58Ni and 40Ca + 64Ni systems at beam energies ranging from E lab = 104.75 MeV to 153.5 MeV using the Laboratori Nazionali di Legnaro electrostatic deflector. Distributions of barriers have been extracted from the experimental data. Preliminary coupled channel calculations were performed and hints of effects of neutron transfers on the fusion below the barrier in the 40Ca + 64Ni are discussed.

Registered Nurses' Experiences With Individuals With Low Health Literacy: A Qualitative Descriptive Study.

PubMed

Toronto, Coleen E; Weatherford, Barbara

2016-01-01

The nursing profession is charged to provide effective communication and education to patients. A qualitative descriptive study that explored what nurses experience when interacting with patients thought to possess low health literacy was performed. Findings suggest that nurses are promoting health literacy using several evidence-based strategies. Major barriers encountered by nurses were limited cultural and linguistic resources within their healthcare organizations. This study provides nursing professional development specialists information about the educational gaps of nurses in practice related to health literacy and the identification of systems barriers.

All-printable band-edge modulated ZnO nanowire photodetectors with ultra-high detectivity

PubMed Central

Liu, Xi; Gu, Leilei; Zhang, Qianpeng; Wu, Jiyuan; Long, Yunze; Fan, Zhiyong

2014-01-01

High-performance photodetectors are critical for high-speed optical communication and environmental sensing, and flexible photodetectors can be used for a wide range of portable or wearable applications. Here we demonstrate the all-printable fabrication of polycrystalline nanowire-based high-performance photodetectors on flexible substrates. Systematic investigations have shown their ultra-high photoconductive gain, responsivity and detectivity up to 3.3 × 1017 Jones. Further analysis shows that their high performance originates from the unique band-edge modulation along the nanowire axial direction, where the existence of Schottky barriers in series leads to highly suppressed dark current of the device and also gives rise to fast photoelectric response to low-intensity optical signal owing to barrier height modulation. The discovered rationale in this work can be utilized as guideline to design high-performance photodetectors with other nanomaterial systems. The developed fabrication scheme opens up possibility for future flexible and high-performance integrated optoelectronic sensor circuitry. PMID:24898081

All-printable band-edge modulated ZnO nanowire photodetectors with ultra-high detectivity.

PubMed

Liu, Xi; Gu, Leilei; Zhang, Qianpeng; Wu, Jiyuan; Long, Yunze; Fan, Zhiyong

2014-06-05

High-performance photodetectors are critical for high-speed optical communication and environmental sensing, and flexible photodetectors can be used for a wide range of portable or wearable applications. Here we demonstrate the all-printable fabrication of polycrystalline nanowire-based high-performance photodetectors on flexible substrates. Systematic investigations have shown their ultra-high photoconductive gain, responsivity and detectivity up to 3.3 × 10(17) Jones. Further analysis shows that their high performance originates from the unique band-edge modulation along the nanowire axial direction, where the existence of Schottky barriers in series leads to highly suppressed dark current of the device and also gives rise to fast photoelectric response to low-intensity optical signal owing to barrier height modulation. The discovered rationale in this work can be utilized as guideline to design high-performance photodetectors with other nanomaterial systems. The developed fabrication scheme opens up possibility for future flexible and high-performance integrated optoelectronic sensor circuitry.

A Survey of Challenges in Aerodynamic Exhaust Nozzle Technology for Aerospace Propulsion Applications

NASA Technical Reports Server (NTRS)

Shyne, Rickey J.

2002-01-01

The current paper discusses aerodynamic exhaust nozzle technology challenges for aircraft and space propulsion systems. Technology advances in computational and experimental methods have led to more accurate design and analysis tools, but many major challenges continue to exist in nozzle performance, jet noise and weight reduction. New generations of aircraft and space vehicle concepts dictate that exhaust nozzles have optimum performance, low weight and acceptable noise signatures. Numerous innovative nozzle concepts have been proposed for advanced subsonic, supersonic and hypersonic vehicle configurations such as ejector, mixer-ejector, plug, single expansion ramp, altitude compensating, lobed and chevron nozzles. This paper will discuss the technology barriers that exist for exhaust nozzles as well as current research efforts in place to address the barriers.

Evaluation of the performance of portable precast concrete traffic barriers.

DOT National Transportation Integrated Search

1978-01-01

The portable precast concrete traffic barrier is used to separate high speed vehicular traffic and construction activities. However, since there was a lack of information on the barrier's performance in a construction zone environment, officials of t...

Capillary Liquid Acquisition Device Heat Entrapment

NASA Technical Reports Server (NTRS)

Bolshinskiy, L. G.; Hastings, L. J.; Statham, G.; Turpin, J. B.

2007-01-01

Cryogenic liquid acquisition devices (LADs) for space-based propulsion interface directly with the feed system, which can be a significant heat leak source. Further, the accumulation of thermal energy within LAD channels can lead to the loss of subcooled propellant conditions and result in feed system cavitation during propellant outflow. Therefore, the fundamental question addressed by this program was: To what degree is natural convection in a cryogenic liquid constrained by the capillary screen meshes envisioned for LADs? Testing was first conducted with water as the test fluid, followed by LN2 tests. In either case, the basic experimental approach was to heat the bottom of a cylindrical column of test fluid to establish stratification patterns measured by temperature sensors located above and below a horizontal screen barrier position. Experimentation was performed without barriers, with screens, and with a solid barrier. The two screen meshes tested were those typically used by LAD designers, 200x1400 and 325x2300, both with Twill Dutch Weave. Upon consideration of both the water and LN2 data, it was concluded that heat transfer across the screen meshes was dependent upon barrier thermal conductivity and that the capillary screen meshes were impervious to natural convection currents.

Cryogenic Capillary Screen Heat Entrapment

NASA Technical Reports Server (NTRS)

Bolshinskiy, L.G.; Hastings, L.J.; Stathman, G.

2007-01-01

Cryogenic liquid acquisition devices (LADs) for space-based propulsion interface directly with the feed system, which can be a significant heat leak source. Further, the accumulation of thermal energy within LAD channels can lead to the loss of sub-cooled propellant conditions and result in feed system cavitation during propellant outflow. Therefore, the fundamental question addressed by this program was: "To what degree is natural convection in a cryogenic liquid constrained by the capillary screen meshes envisioned for LADs.?"Testing was first conducted with water as the test fluid, followed by LN2 tests. In either case, the basic experimental approach was to heat the bottom of a cylindrical column of test fluid to establish stratification patterns measured by temperature sensors located above and below a horizontal screen barrier position. Experimentation was performed without barriers, with screens, and with a solid barrier. The two screen meshes tested were those typically used by LAD designers, "200x1400" and "325x2300", both with Twill Dutch Weave. Upon consideration of both the water and LN2 data it was concluded that heat transfer across the screen meshes was dependent upon barrier thermal conductivity and that the capillary screen meshes were impervious to natural convection currents.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbose, Galen; Wiser, Ryan; Bolinger, Mark

Increasing levels of financial support for customer-sited photovoltaic (PV) systems, provided through publicly-funded incentive programs, has heightened concerns about the long-term performance of these systems. Given the barriers that customers face to ensuring that their PV systems perform well, and the responsibility that PV incentive programs bear to ensure that public funds are prudently spent, these programs should, and often do, play a critical role in ensuring that PV systems receiving incentives perform well. To provide a point of reference for assessing the current state of the art, and to inform program design efforts going forward, we examine the approachesmore » to encouraging PV system performance used by 32 prominent PV incentive programs in the U.S. We identify eight general strategies or groups of related strategies that these programs have used to address performance issues, and highlight important differences in the implementation of these strategies among programs.« less

Alternating InGaN barriers with GaN barriers for enhancing optical performance in InGaN light-emitting diodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yujue; Zeng, Yiping, E-mail: ypzeng@semi.ac.cn

2015-01-21

InGaN-based light-emitting diodes (LEDs) with some specific designs on the quantum barrier layers by alternating InGaN barriers with GaN barriers are proposed and studied numerically. In the proposed structure, simulation results show that the carriers are widely dispersed in the multi-quantum well active region, and the radiative recombination rate is efficiently improved and the electron leakage is suppressed accordingly, due to the appropriate band engineering. The internal quantum efficiency and light-output power are thus markedly enhanced and the efficiency droop is smaller, compared to the original structures with GaN barriers or InGaN barriers. Moreover, the gradually decrease of indium compositionmore » in the alternating quantum barriers can further promote the LED performance because of the more uniform carrier distribution, which provides us a simple but highly effective approach for high-performance LED applications.« less

Perceived and objective entrance-related environmental barriers and daily out-of-home mobility in community-dwelling older people.

PubMed

Portegijs, Erja; Rantakokko, Merja; Viljanen, Anne; Rantanen, Taina; Iwarsson, Susanne

We studied whether entrance-related environmental barriers, perceived and objectively recorded, were associated with moving out-of-home daily in older people with and without limitations in lower extremity performance. Cross-sectional analyses of the "Life-space mobility in old age" cohort including 848 community-dwelling 75-90-year-old of central Finland. Participants reported their frequency of moving out-of-home (daily vs. 0-6 times/week) and perceived entrance-related environmental barriers (yes/no). Lower extremity performance was assessed (Short Physical Performance Battery) and categorized as poorer (score 0-9) or good (score 10-12). Environmental barriers at entrances and in exterior surroundings were objectively registered (Housing Enabler screening tool) and divided into tertiles. Logistic regression analyses were adjusted for age, sex, number of chronic diseases, cognitive function, month of assessment, type of neighborhood, and years lived in the current home. At home entrances a median of 6 and in the exterior surroundings 5 environmental barriers were objectively recorded, and 20% of the participants perceived entrance-related barriers. The odds for moving out-of-home less than daily increased when participants perceived entrance-related barrier(s) or when they lived in homes with higher numbers of objectively recorded environmental barriers at entrances. Participants with limitations in lower extremity performance were more susceptible to these environmental barriers. Objectively recorded environmental barriers in the exterior surroundings did not compromise out-of-home mobility. Entrance-related environmental barriers may hinder community-dwelling older people to move out-of-home daily especially when their functional capacity is compromised. Potentially, reducing entrance-related barriers may help to prevent confinement to the home. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Role of structural relaxations and chemical substitutions on piezoelectric fields and potential lineup in GaN/Al junctions

NASA Astrophysics Data System (ADS)

Picozzi, S.; Profeta, G.; Continenza, A.; Massidda, S.; Freeman, A. J.

2002-04-01

First-principles full-potential linearized augmented plane wave calculations are performed to clarify the role of the interface geometry on piezoelectric fields and potential lineups in [0001] wurtzite and [111]-zincblende GaN/Al junctions. The electric field (polarity and magnitude) is found to be strongly affected by atomic relaxations in the interface region. A procedure is used to evaluate the Schottky-barrier height in the presence of electric fields, showing that their effect is relatively small (a few tenths of an eV). These calculations assess the rectifying behavior of the GaN/Al contact, in agreement with experimental values for the barrier. We disentangle chemical and structural effects on the relevant properties (such as the potential discontinuity and the electric field) by studying unrelaxed ideal nitride/metal systems. Using simple electronegativity arguments, we outline the leading mechanisms that define the values of the electric field and Schottky barrier in these ideal systems. Finally, the transitivity rule is proved to be well satisfied.

Are Chinese Students Willing to Learn and Perform Bystander Cardiopulmonary Resuscitation?

PubMed

Huang, Qiao; Hu, Cuihuan; Mao, Jing

2016-12-01

Immediate cardiopulmonary resuscitation (CPR) can improve survival rate from cardiac arrest and students are potentially important bystander CPR providers. Our aim was to investigate the willingness among Chinese students to learn and perform bystander CPR. Questionnaires were distributed to 1407 students. The survey investigated the willingness to learn and perform bystander CPR and the barriers to performing CPR on family members and strangers, assuming that students had mastered CPR. Only 14.6% of respondents reported having ever attended CPR training classes, however, 88.3% expressed their willingness to learn. The main characteristics of the students who were willing to learn were the following: they considered the development of the local emergency system excellent (odds ratio [OR] = 3.15); cardiovascular diseases were present within their family (OR = 2.74); and they had previously heard about CPR (OR = 2.43). Almost all respondents (94.6%) reported that they would conduct bystander CPR on family members, while only 59.7% of respondents would do it for strangers. A lack of confidence was the principal barrier to doing CPR for family members (78.4%) and the leading barrier to stranger CPR was the fear of legal liability if their lifesaving attempts failed (90.8%). The complicated process of performing CPR was also a major barrier in both scenarios. When there is a great desire to learn CPR, the rate and effect of training can be significantly improved by providing students with regular CPR training, especially compression-only CPR training. Training classes should focus on enhancing the participants' confidence. In addition, legislation by the government is needed to protect the rescuers. Copyright © 2016 Elsevier Inc. All rights reserved.

Structural details of Al/Al 2O3 junctions and their role in the formation of electron tunnel barriers

NASA Astrophysics Data System (ADS)

Koberidze, M.; Puska, M. J.; Nieminen, R. M.

2018-05-01

We present a computational study of the adhesive and structural properties of the Al/Al 2O3 interfaces as building blocks of the metal-insulator-metal (MIM) tunnel devices, where electron transport is accomplished via tunneling mechanism through the sandwiched insulating barrier. The main goal of this paper is to understand, on the atomic scale, the role of the geometrical details in the formation of the tunnel barrier profiles. Initially, we concentrate on the adhesive properties of the interfaces. To provide reliable results, we carefully assess the accuracy of the traditional methods used to examine Al/Al 2O3 systems. These are the most widely employed exchange-correlation functionals—local-density approximation and two different generalized gradient approximations; the universal binding-energy relation for predicting equilibrium interfacial distances and adhesion energies; and the ideal work of separation as a measure of junction stability. In addition, we show that the established interpretation of the computed ideal work of separation might be misleading in predicting the optimal interface structures. Finally, we perform a detailed analysis of the atomic and interplanar relaxations in each junction, and identify their contributions to the tunnel barrier parameters. Our results imply that the structural irregularities on the surface of the Al film have a significant contribution to lowering the tunnel barrier height, while atomic relaxations at the interface and interplanar relaxations in Al2O3 may considerably change the width of the barrier and, thus, distort its uniformity. Both the effects may critically influence the performance of the MIM tunnel devices.

The declared barriers of the large developing countries waste management projects: The STAR model.

PubMed

Bufoni, André Luiz; Oliveira, Luciano Basto; Rosa, Luiz Pinguelli

2016-06-01

The aim of this study is to investigate and describe the barriers system that precludes the feasibility, or limits the performance of the waste management projects through the analysis of which are the declared barriers at the 432 large waste management projects registered as CDM during the period 2004-2014. The final product is a waste management barriers conceptual model proposal (STAR), supported by literature and corroborated by projects design documents. This paper uses the computer assisted qualitative content analysis (CAQCA) methodology with the qualitative data analysis (QDA) software NVivo®, by 890 fragments, to investigate the motives to support our conclusions. Results suggest the main barriers classification in five types: sociopolitical, technological, regulatory, financial, and human resources constraints. Results also suggest that beyond the waste management industry, projects have disadvantages added related to the same barriers inherent to others renewable energies initiatives. The STAR model sheds some light over the interactivity and dynamics related to the main constraints of the industry, describing the mutual influences and relationships among each one. Future researches are needed to better and comprehensively understand these relationships and ease the development of tools to alleviate or eliminate them. Copyright © 2016 Elsevier Ltd. All rights reserved.

Coupling Influences SMM Properties for Pure 4 f Systems.

PubMed

Zhang, Xuejing; Liu, Shuang; Vieru, Veacheslav; Xu, Na; Gao, Chen; Wang, Bing-Wu; Shi, Wei; Chibotaru, Liviu F; Gao, Song; Cheng, Peng; Powell, Annie K

2018-04-20

Increasing both the energy barrier for magnetization reversal and the coercive field of the hysteresis loop are significant challenges in the field of single-molecule magnets (SMMs). Coordination geometries of lanthanide ions and magnetic interactions between lanthanide ions are both important for guiding the magnetic behavior of SMMs. We report a high energy barrier of 657 K (457 cm -1 ) in a diamagnetic-ion-diluted lanthanide chain compound with a constrained bisphenoid symmetry (D 2d ); this energy barrier is substantially higher than the barrier of 567 K (394 cm -1 ) of the non-diluted chain compound with intrachain ferromagnetic interactions. Although intrachain magnetic interaction lowers the energy barrier for magnetization reversal, it can greatly enhance the coercive fields and zero-field remanence of the hysteresis loops, which is crucial for the rational design of high-performance SMMs. Factors related to the coordination sphere of the lanthanide center, which govern the high magnetic relaxation barriers through the second excited Kramer's doublets and the magnetic interactions that affect the hysteresis loops, were revealed through ab initio calculations. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Live Faecalibacterium prausnitzii Does Not Enhance Epithelial Barrier Integrity in an Apical Anaerobic Co-Culture Model of the Large Intestine.

PubMed

Maier, Eva; Anderson, Rachel C; Roy, Nicole C

2017-12-12

Appropriate intestinal barrier maturation during infancy largely depends on colonization with commensal bacteria. Faecalibacterium prausnitzii is an abundant obligate anaerobe that colonizes during weaning and is thought to maintain colonic health throughout life. We previously showed that F. prausnitzii induced Toll-like receptor 2 (TLR2) activation, which is linked to enhanced tight junction formation. Therefore, we hypothesized that F. prausnitzii enhances barrier integrity, an important factor in appropriate intestinal barrier maturation. In order to test metabolically active bacteria, we used a novel apical anaerobic co-culture system that allows the survival of both obligate anaerobic bacteria and oxygen-requiring intestinal epithelial cells (Caco-2). The first aim was to optimize the culture medium to enable growth and active metabolism of F. prausnitzii while maintaining the viability and barrier integrity, as measured by trans-epithelial electrical resistance (TEER), of the Caco-2 cells. This was achieved by supplementing the apical cell culture medium with bacterial culture medium. The second aim was to test the effect of F. prausnitzii on TEER across Caco-2 cell layers. Live F. prausnitzii did not improve TEER, which indicates that its benefits are not via altering tight junction integrity. The optimization of the novel dual-environment co-culturing system performed in this research will enable the investigation of new probiotics originating from indigenous beneficial bacteria.

Live Faecalibacterium prausnitzii Does Not Enhance Epithelial Barrier Integrity in an Apical Anaerobic Co-Culture Model of the Large Intestine

PubMed Central

Maier, Eva; Anderson, Rachel C.; Roy, Nicole C.

2017-01-01

Appropriate intestinal barrier maturation during infancy largely depends on colonization with commensal bacteria. Faecalibacterium prausnitzii is an abundant obligate anaerobe that colonizes during weaning and is thought to maintain colonic health throughout life. We previously showed that F. prausnitzii induced Toll-like receptor 2 (TLR2) activation, which is linked to enhanced tight junction formation. Therefore, we hypothesized that F. prausnitzii enhances barrier integrity, an important factor in appropriate intestinal barrier maturation. In order to test metabolically active bacteria, we used a novel apical anaerobic co-culture system that allows the survival of both obligate anaerobic bacteria and oxygen-requiring intestinal epithelial cells (Caco-2). The first aim was to optimize the culture medium to enable growth and active metabolism of F. prausnitzii while maintaining the viability and barrier integrity, as measured by trans-epithelial electrical resistance (TEER), of the Caco-2 cells. This was achieved by supplementing the apical cell culture medium with bacterial culture medium. The second aim was to test the effect of F. prausnitzii on TEER across Caco-2 cell layers. Live F. prausnitzii did not improve TEER, which indicates that its benefits are not via altering tight junction integrity. The optimization of the novel dual-environment co-culturing system performed in this research will enable the investigation of new probiotics originating from indigenous beneficial bacteria. PMID:29231875

Rocket thrust chamber thermal barrier coatings

NASA Technical Reports Server (NTRS)

Batakis, A. P.; Vogan, J. W.

1985-01-01

A research program was conducted to generate data and develop analytical techniques to predict the performance and reliability of ceramic thermal barrier coatings in high heat flux environments. A finite element model was used to analyze the thermomechanical behavior of coating systems in rocket thrust chambers. Candidate coating systems (using a copper substrate, NiCrAlY bond coat and ZrO2.8Y2O3 ceramic overcoat) were selected for detailed study based on photomicrographic evaluations of experimental test specimens. The effects of plasma spray application parameters on the material properties of these coatings were measured and the effects on coating performance evaluated using the finite element model. Coating design curves which define acceptable operating envelopes for seleted coating systems were constructed based on temperature and strain limitations. Spray gun power levels was found to have the most significant effect on coating structure. Three coating systems were selected for study using different power levels. Thermal conductivity, strain tolerance, density, and residual stress were measured for these coatings. Analyses indicated that extremely thin coatings ( 0.02 mm) are required to accommodate the high heat flux of a rocket thrust chamber and ensure structural integrity.

Fusion hindrance for the positive Q -value system 12C+30Si

NASA Astrophysics Data System (ADS)

Montagnoli, G.; Stefanini, A. M.; Jiang, C. L.; Hagino, K.; Galtarossa, F.; Colucci, G.; Bottoni, S.; Broggini, C.; Caciolli, A.; Čolović, P.; Corradi, L.; Courtin, S.; Depalo, R.; Fioretto, E.; Fruet, G.; Gal, A.; Goasduff, A.; Heine, M.; Hu, S. P.; Kaur, M.; Mijatović, T.; Mazzocco, M.; Montanari, D.; Scarlassara, F.; Strano, E.; Szilner, S.; Zhang, G. X.

2018-02-01

Background: The fusion reaction 12C+30Si is a link between heavier cases studied in recent years, and the light heavy-ion systems, e.g., 12C+12C , 16O+16O that have a prominent role in the dynamics of stellar evolution. 12C+30Si fusion itself is not a relevant process for astrophysics, but it is important to establish its behavior below the barrier, where couplings to low-lying collective modes and the hindrance phenomenon may determine the cross sections. The excitation function is presently completely unknown below the barrier for the 12C+30Si reaction, thus no reliable extrapolation into the astrophysical regime for the C+C and O+O cases can be performed. Purpose: Our aim was to carry out a complete measurement of the fusion excitation function of 12C+30Si from well below to above the Coulomb barrier, so as to clear up the consequence of couplings to low-lying states of 30Si, and whether the hindrance effect appears in this relatively light system which has a positive Q value for fusion. This would have consequences for the extrapolated behavior to even lighter systems. Methods: The inverse kinematics was used by sending 30Si beams delivered from the XTU Tandem accelerator of INFN-Laboratori Nazionali di Legnaro onto thin 12C (50 μ g /cm2 ) targets enriched to 99.9 % in mass 12. The fusion evaporation residues (ER) were detected at very forward angles, following beam separation by means of an electrostatic deflector. Angular distributions of ER were measured at Ebeam=45 , 59, and 80 MeV, and they were angle integrated to derive total fusion cross sections. Results: The fusion excitation function of 12C+30Si was measured with high statistical accuracy, covering more than five orders of magnitude down to a lowest cross section ≃3 μ b . The logarithmic slope and the S factor have been extracted and we have convincing phenomenological evidence of the hindrance effect. These results have been compared with the calculations performed within the model that considers a damping of the coupling strength well inside the Coulomb barrier. Conclusions: The experimental data are consistent with the coupled-channels calculations. A better fit is obtained by using the Yukawa-plus-exponential potential and a damping of the coupling strengths inside the barrier. The degree of hindrance is much smaller than the one in heavier systems. Also a phenomenological estimate reproduces quite closely the hindrance threshold for 12C+30Si , so that an extrapolation to the C+C and O+O cases can be reliably performed.

Feasibility of antihydrogen atom containment in helium: a problem of electron-positron correlation investigated by the Monte Carol method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jackman, T.M.

1987-01-01

A theoretical investigation of the interaction potential between the helium atom and the antihydrogen atom was performed for the purpose of determining the feasibility of antihydrogen atom containment. The interaction potential showed an energy barrier to collapse of this system. A variational estimate of the height of this energy barrier and estimates of lifetime with respect to electron-positron annihilation were determined by the Variational Monte Carlo method. This calculation allowed for an improvement over an SCF result through the inclusion of explicit correlation factors in the trial wave function. An estimate of the correlation energy of this system was determinedmore » by the Green's Function Monte Carlo (GFMC) method.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huff, Kathryn D.

Component level and system level abstraction of detailed computational geologic repository models have resulted in four rapid computational models of hydrologic radionuclide transport at varying levels of detail. Those models are described, as is their implementation in Cyder, a software library of interchangeable radionuclide transport models appropriate for representing natural and engineered barrier components of generic geology repository concepts. A proof of principle demonstration was also conducted in which these models were used to represent the natural and engineered barrier components of a repository concept in a reducing, homogenous, generic geology. This base case demonstrates integration of the Cyder openmore » source library with the Cyclus computational fuel cycle systems analysis platform to facilitate calculation of repository performance metrics with respect to fuel cycle choices. (authors)« less

Barriers to Innovation in Continuing Medical Education

ERIC Educational Resources Information Center

Bower, Elizabeth A.; Girard, Donald E.; Wessel, Kristen; Becker, Thomas M.; Choi, Dongseok

2008-01-01

Introduction: Criteria for maintenance of certification (MOC) emphasize the importance of competencies such as communication, professionalism, systems-based care, and practice performance in addition to medical knowledge. Success of this new competency paradigm is dependent on physicians' willingness to engage in activities that focus on less…

Influence of the Rh (D) blood group system on graft survival in renal transplantation.

PubMed

Bryan, C F; Mitchell, S I; Lin, H M; Nelson, P W; Shield, C F; Luger, A M; Pierce, G E; Ross, G; Warady, B A; Aeder, M I; Helling, T S; Landreneau, M D; Harrell, K M

1998-02-27

The Rh (D) blood group system has not traditionally been considered to be a clinically relevant histocompatibility barrier in transplantation since conflicting results of its clinical importance have been reported. We analyzed 786 consecutive primary cadaveric renal transplants performed by transplant centers in our Organ Procurement Organization (OPO) between 1990 and 1997. We also analyzed United Network for Organ Sharing (UNOS) data on 26,469 kidney transplants done from April 1994 to June 1996. Multivariate analysis revealed that Rh identity between the recipient and donor was significantly related to better graft outcome (risk ratio, 0.43; 95% confidence interval, 0.30 to 0.61; P=0.0001). Multivariate analysis of the UNOS data revealed that the Rh -/- group may have a positive influence on graft survival with a risk ratio of 0.43 (P=0.14). Multivariate analysis of primary cadaveric renal allografts performed within the Midwest Organ Bank OPO indicates that Rh (D) is a clinically relevant histocompatibility barrier that influences 7-year graft survival.

Barriers to genuine consumer and carer participation from the perspectives of Australian systemic mental health advocates.

PubMed

Gee, Alison; McGarty, Craig; Banfield, Michelle

2016-06-01

Consumer and carer participation in mental health service development and evaluation has widespread nominal support. However, genuine and consistent participation remains elusive due to systemic barriers. This paper explores barriers to reform for mental health services from the perspectives of consumers and carers actively engaged in advocating for improvements in the mental health system. Qualitative research with two mental health systemic advocacy organisations analysed 17 strategic communication documents and nine interviews to examine barriers to reform and participation identified by consumer and carer advocates and staff. A number of individual-level barriers were described, however advocates gave more focus to systemic barriers, for which five themes emerged. These reflected lack of awareness, limited participation opportunities, slow progress for change, policy issues and mental health culture including stigma. Findings highlight systemic barriers to participation for consumer and carer advocates as a whole and the influence of these barriers on the individual experiences of those engaged in advocacy and representation work. Participants also emphasised the need for leadership to overcome some of these obstacles and move towards genuine consumer and carer participation and reform. Findings are discussed in the context of power within mental health systems.

Systems thinking in practice: the current status of the six WHO building blocks for health system strengthening in three BHOMA intervention districts of Zambia: a baseline qualitative study

PubMed Central

2013-01-01

Background The primary bottleneck to achieving the MDGs in low-income countries is health systems that are too fragile to deliver the volume and quality of services to those in need. Strong and effective health systems are increasingly considered a prerequisite to reducing the disease burden and to achieving the health MDGs. Zambia is one of the countries that are lagging behind in achieving millennium development targets. Several barriers have been identified as hindering the progress towards health related millennium development goals. Designing an intervention that addresses these barriers was crucial and so the Better Health Outcomes through Mentorship (BHOMA) project was designed to address the challenges in the Zambia’s MOH using a system wide approach. We applied systems thinking approach to describe the baseline status of the Six WHO building blocks for health system strengthening. Methods A qualitative study was conducted looking at the status of the Six WHO building blocks for health systems strengthening in three BHOMA districts. We conducted Focus group discussions with community members and In-depth Interviews with key informants. Data was analyzed using Nvivo version 9. Results The study showed that building block specific weaknesses had cross cutting effect in other health system building blocks which is an essential element of systems thinking. Challenges noted in service delivery were linked to human resources, medical supplies, information flow, governance and finance building blocks either directly or indirectly. Several barriers were identified as hindering access to health services by the local communities. These included supply side barriers: Shortage of qualified health workers, bad staff attitude, poor relationships between community and health staff, long waiting time, confidentiality and the gender of health workers. Demand side barriers: Long distance to health facility, cost of transport and cultural practices. Participating communities seemed to lack the capacity to hold health workers accountable for the drugs and services. Conclusion The study has shown that building block specific weaknesses had cross cutting effect in other health system building blocks. These linkages emphasised the need to use system wide approaches in assessing the performance of health system strengthening interventions. PMID:23902601

A high performance, cost-effective, open-source microscope for scanning two-photon microscopy that is modular and readily adaptable.

PubMed

Rosenegger, David G; Tran, Cam Ha T; LeDue, Jeffery; Zhou, Ning; Gordon, Grant R

2014-01-01

Two-photon laser scanning microscopy has revolutionized the ability to delineate cellular and physiological function in acutely isolated tissue and in vivo. However, there exist barriers for many laboratories to acquire two-photon microscopes. Additionally, if owned, typical systems are difficult to modify to rapidly evolving methodologies. A potential solution to these problems is to enable scientists to build their own high-performance and adaptable system by overcoming a resource insufficiency. Here we present a detailed hardware resource and protocol for building an upright, highly modular and adaptable two-photon laser scanning fluorescence microscope that can be used for in vitro or in vivo applications. The microscope is comprised of high-end componentry on a skeleton of off-the-shelf compatible opto-mechanical parts. The dedicated design enabled imaging depths close to 1 mm into mouse brain tissue and a signal-to-noise ratio that exceeded all commercial two-photon systems tested. In addition to a detailed parts list, instructions for assembly, testing and troubleshooting, our plan includes complete three dimensional computer models that greatly reduce the knowledge base required for the non-expert user. This open-source resource lowers barriers in order to equip more laboratories with high-performance two-photon imaging and to help progress our understanding of the cellular and physiological function of living systems.

A High Performance, Cost-Effective, Open-Source Microscope for Scanning Two-Photon Microscopy that Is Modular and Readily Adaptable

PubMed Central

Rosenegger, David G.; Tran, Cam Ha T.; LeDue, Jeffery; Zhou, Ning; Gordon, Grant R.

2014-01-01

Two-photon laser scanning microscopy has revolutionized the ability to delineate cellular and physiological function in acutely isolated tissue and in vivo. However, there exist barriers for many laboratories to acquire two-photon microscopes. Additionally, if owned, typical systems are difficult to modify to rapidly evolving methodologies. A potential solution to these problems is to enable scientists to build their own high-performance and adaptable system by overcoming a resource insufficiency. Here we present a detailed hardware resource and protocol for building an upright, highly modular and adaptable two-photon laser scanning fluorescence microscope that can be used for in vitro or in vivo applications. The microscope is comprised of high-end componentry on a skeleton of off-the-shelf compatible opto-mechanical parts. The dedicated design enabled imaging depths close to 1 mm into mouse brain tissue and a signal-to-noise ratio that exceeded all commercial two-photon systems tested. In addition to a detailed parts list, instructions for assembly, testing and troubleshooting, our plan includes complete three dimensional computer models that greatly reduce the knowledge base required for the non-expert user. This open-source resource lowers barriers in order to equip more laboratories with high-performance two-photon imaging and to help progress our understanding of the cellular and physiological function of living systems. PMID:25333934

Neurotoxicology of the Brain Barrier System: New Implications

PubMed Central

Zheng, Wei

2014-01-01

The concept of a barrier system in the brain has existed for nearly a century. The barrier that separates the blood from the cerebral interstitial fluid is defined as the blood-brain barrier, while the one that discontinues the circulation between the blood and cerebrospinal fluid is named the blood-cerebrospinal fluid barrier. Evidence in the past decades suggests that brain barriers are subject to toxic insults from neurotoxic chemicals circulating in blood. The aging process and some disease states render barriers more vulnerable to insults arising inside and outside the barriers. The implication of brain barriers in certain neurodegenerative diseases is compelling, although the contribution of chemical-induced barrier dysfunction in the etiology of any of these disorders remains poorly understood. This review examines what is currently understood about brain barrier systems in central nervous system disorders by focusing on chemical-induced neurotoxicities including those associated with nitrobenzenes, N-methyl-D-aspartate, cyclosporin A, pyridostigmine bromide, aluminum, lead, manganese, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, and 3-nitropropionic acid. Contemporary research questions arising from this growing understanding show enormous promises for brain researchers, toxicologists, and clinicians. PMID:11778669

76 FR 56215 - John H. Chafee Coastal Barrier Resources System; Baldwin and Mobile Counties, AL; Availability of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-12

... aquatic habitat. These areas are depicted on a series of maps entitled ``John H. Chafee Coastal Barrier...] John H. Chafee Coastal Barrier Resources System; Baldwin and Mobile Counties, AL; Availability of Draft... availability of a John H. Chafee Coastal Barrier Resources System (CBRS) draft revised map, dated September 22...

ENGINEERED BARRIER SYSTEM: PHYSICAL AND CHEMICAL ENVIRONMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. Jarek

2005-08-29

The purpose of this model report is to describe the evolution of the physical and chemical environmental conditions within the waste emplacement drifts of the repository, including the drip shield and waste package surfaces. The resulting seepage evaporation and gas abstraction models are used in the total system performance assessment for the license application (TSPA-LA) to assess the performance of the engineered barrier system and the waste form. This report develops and documents a set of abstraction-level models that describe the engineered barrier system physical and chemical environment. Where possible, these models use information directly from other reports as input,more » which promotes integration among process models used for TSPA-LA. Specific tasks and activities of modeling the physical and chemical environment are included in ''Technical Work Plan for: Near-Field Environment and Transport In-Drift Geochemistry Model Report Integration'' (BSC 2005 [DIRS 173782], Section 1.2.2). As described in the technical work plan, the development of this report is coordinated with the development of other engineered barrier system reports. To be consistent with other project documents that address features, events, and processes (FEPs), Table 6.14.1 of the current report includes updates to FEP numbers and FEP subjects for two FEPs identified in the technical work plan (TWP) governing this report (BSC 2005 [DIRS 173782]). FEP 2.1.09.06.0A (Reduction-oxidation potential in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.06.0B (Reduction-oxidation potential in Drifts; see Table 6.14-1). FEP 2.1.09.07.0A (Reaction kinetics in EBS), as listed in Table 2 of the TWP (BSC 2005 [DIRS 173782]), has been updated in the current report to FEP 2.1.09.07.0B (Reaction kinetics in Drifts; see Table 6.14-1). These deviations from the TWP are justified because they improve integration with FEPs documents. The updates have no impact on the model developed in this report.« less

Comparison of MWIR unipolar barrier structures based on strained layer superlattices (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ramirez, David A.; Myers, Stephen A.; Kuznetsova, Yuliya; Mathews, Sen; Schuler-Sandy, Theodore; Steenbergen, Elizabeth H.; Morath, Christian P.; Cowan, Vicent M.; Krishna, Sanjay

2016-09-01

In this work, we compare the performance of three MWIR unipolar barrier structures based on the InAs/GaSb Type-2 strained layer superlattice material system. We have designed, fabricated, and characterized pBiBn, pBn, and pBp detector structures. All the structures have been designed so that the cut off wavelength is around 5 microns at 100 K. We fabricated single-pixel devices and characterize their radiometric performance. In addition, we have characterized the degradation of the performance of the devices after exposing the devices to 63 MeV proton radiation to total ionizing dose of 100 kRad (Si). In this report, we compare the performance of the different structures with the objective of determining the advantages and disadvantages of the different designs. This work was supported by the Small Business Innovation Research (SBIR) program under the contract FA9453-14-C-0032, sponsored by the Air Force Research Laboratory (AFRL).

Modeling of influencing parameters in active noise control on an enclosure wall

NASA Astrophysics Data System (ADS)

Tarabini, Marco; Roure, Alain

2008-04-01

This paper investigates, by means of a numerical model, the possibility of using an active noise barrier to virtually reduce the acoustic transparency of a partition wall inside an enclosure. The room is modeled with the image method as a rectangular enclosure with a stationary point source; the active barrier is set up by an array of loudspeakers and error microphones and is meant to minimize the squared sound pressure on a wall with the use of a decentralized control. Simulations investigate the effects of the enclosure characteristics and of the barrier geometric parameters on the sound pressure attenuation on the controlled partition, on the whole enclosure potential energy and on the diagonal control stability. Performances are analyzed in a frequency range of 25-300 Hz at discrete 25 Hz steps. Influencing parameters and their effects on the system performances are identified with a statistical inference procedure. Simulation results have shown that it is possible to averagely reduce the sound pressure on the controlled partition. In the investigated configuration, the surface attenuation and the diagonal control stability are mainly driven by the distance between the loudspeakers and the error microphones and by the loudspeakers directivity; minor effects are due to the distance between the error microphones and the wall, by the wall reflectivity and by the active barrier grid meshing. Room dimensions and source position have negligible effects. Experimental results point out the validity of the model and the efficiency of the barrier in the reduction of the wall acoustic transparency.

Mapping barriers and intervention activities to behaviour change theory for Mobilization of Vulnerable Elders in Ontario (MOVE ON), a multi-site implementation intervention in acute care hospitals.

PubMed

Moore, Julia E; Mascarenhas, Alekhya; Marquez, Christine; Almaawiy, Ummukulthum; Chan, Wai-Hin; D'Souza, Jennifer; Liu, Barbara; Straus, Sharon E

2014-10-30

As evidence-informed implementation interventions spread, they need to be tailored to address the unique needs of each setting, and this process should be well documented to facilitate replication. To facilitate the spread of the Mobilization of Vulnerable Elders in Ontario (MOVE ON) intervention, the aim of the current study is to develop a mapping guide that links identified barriers and intervention activities to behaviour change theory. Focus groups were conducted with front line health-care professionals to identify perceived barriers to implementation of an early mobilization intervention targeted to hospitalized older adults. Participating units then used or adapted intervention activities from an existing menu or developed new activities to facilitate early mobilization. A thematic analysis was performed on the focus group data, emphasizing concepts related to barriers to behaviour change. A behaviour change theory, the 'capability, opportunity, motivation-behaviour (COM-B) system', was used as a taxonomy to map the identified barriers to their root causes. We also mapped the behaviour constructs and intervention activities to overcome these. A total of 46 focus groups were conducted across 26 hospital inpatient units in Ontario, Canada, with 261 participants. The barriers were conceptualized at three levels: health-care provider (HCP), patient, and unit. Commonly mentioned barriers were time constraints and workload (HCP), patient clinical acuity and their perceived 'sick role' (patient), and lack of proper equipment and human resources (unit level). Thirty intervention activities to facilitate early mobilization of older adults were implemented across hospitals; examples of unit-developed intervention activities include the 'mobility clock' communication tool and the use of staff champions. A mapping guide was created with barriers and intervention activities matched though the lens of the COM-B system. We used a systematic approach to develop a guide, which maps barriers, intervention activities, and behaviour change constructs in order to tailor an implementation intervention to the local context. This approach allows implementers to identify potential strategies to overcome local-level barriers and to document adaptations.

Evaluation of DCS III Transmission Alternatives. Phase 1A report. Appendix B. Regulatory Barriers.

DTIC Science & Technology

1980-05-26

greatest impact on transmission system design, and the Q- and V-series deal with switching and signaling, and with data transmission respectively. These...equipments or systems (such as receiver performance papameters). If appropriate technical data are not found in the NTIA Manual provisions of the ITU Radio...under control of the JCS and complying with applicable restrictions. 3. System alternatives should be consistent with projected data prepared for the

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbose, Galen; Wiser, Ryan; Bolinger, Mark

In the U.S., the increasing financial support for customer-sited photovoltaic (PV) systems provided through publicly-funded incentive programs has heightened concerns about the long-term performance of these systems. Given the barriers that customers face to ensuring that their PV systems perform well, and the responsibility that PV incentive programs bear to ensure that public funds are prudently spent, these programs should, and often do, play a critical role in addressing PV system performance. To provide a point of reference for assessing the current state of the art, and to inform program design efforts going forward, we examine the approaches to encouragingmore » PV system performance used by 32 prominent PV incentive programs in the U.S. We identify eight general strategies or groups of related strategies that these programs have used to address factors that affect performance, and describe key implementation details. Based on this review, we then offer recommendations for how PV incentive programs can be effectively designed to mitigate potential performance issues.« less

Mitigation of lava flow invasion hazard through optimized barrier configuration aided by numerical simulation: The case of the 2001 Etna eruption

NASA Astrophysics Data System (ADS)

Scifoni, S.; Coltelli, M.; Marsella, M.; Proietti, C.; Napoleoni, Q.; Vicari, A.; Del Negro, C.

2010-04-01

Lava flow spreading along the flanks of Etna volcano often produces damages to the land and proprieties. The impact of these eruptions could be mitigated by building artificial barriers for controlling and slowing down the lava, as recently experienced in 1983, 1991-1993, 2001 and 2002. This study investigates how numerical simulations can be adopted for evaluating the effectiveness of barrier construction and for optimizing their geometry, considering as test case the lava flows emplaced on Etna's south flank during 2001. The flow temporal evolutions were reconstructed deriving the effusion rate trends, together with the pre-eruption topography were adopted as input data of the MAGFLOW simulation code. Three simulations were then conducted to simulate lava flow with and without barriers. The first aimed at verifying the reconstruction of the effusion rate trends, while the others at assessing the performance of the barrier system realized during the eruption in comparison with an alternative solution here proposed. A quantitative analysis carried out on the first simulation confirms the suitability of the selected test case. The comparison of the three simulated thickness distributions showed both the effectiveness of the barriers in slowing down the lava flow and the sensitivity of the MAGFLOW code to the topographical variations represented by the barriers. Finally, for reducing both the time necessary to erect the barrier and the barrier environmental impact, the gabion's barrier construction was analyzed. The implemented and tested procedure enforces the capability of using numerical simulations for designing optimized lava flow barriers aimed at making swifter mitigatory actions upon lava flows and improving the effectiveness of civil protection interventions during emergencies.

GROUND WATER REMEDIATION OF CHROMIUM USING ZERO-VALENT IRON IN A PERMEABLE REACTIVE BARRIER

EPA Science Inventory

A series of laboratory experiments were performed to elucidate the chromium transformation and precipitation reactions caused by the corrosion of zero-valent iron in water-based systems. Reaction rates were determined for chromate reduction in the presence of different types of ...

Abnormal cerebrospinal fluid protein indices in schizophrenia.

PubMed

Kirch, D G; Kaufmann, C A; Papadopoulos, N M; Martin, B; Weinberger, D R

1985-10-01

Determinations of albumin and immunoglobulin G (IgG) were performed in paired cerebrospinal fluid (CSF) and serum samples from 24 subjects with schizophrenia. These determinations allowed calculation of two indices, one that is an indicator of integrity of the blood-brain barrier and the other a measure of selective IgG production within the central nervous system (CNS). In comparison with previously determined reference values, 7 of 24 (29%) subjects showed increased blood-brain barrier permeability, and 8 of 24 (33%) demonstrated elevated endogenous CNS IgG production. One of these eight also demonstrated oligoclonal banding on high-resolution protein electrophoresis of the CSF.

Environmental and Mechanical Stability of Environmental Barrier Coated SA Tyrannohex SiC Composites Under Simulated Turbine Engine Environments

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Halbig, Michael Charles; Sing, Mrityunjay

2014-01-01

The environmental stability and thermal gradient cyclic durability performance of SA Tyrannohex composites were investigated for turbine engine component applications. The work has been focused on investigating the combustion rig recession, cyclic thermal stress resistance and thermomechanical low cycle fatigue of uncoated and environmental barrier coated Tyrannohex SiC SA composites in simulated turbine engine combustion water vapor, thermal gradients, and mechanical loading conditions. Flexural strength degradations have been evaluated, and the upper limits of operating temperature conditions for the SA composite material systems are discussed based on the experimental results.

Principals' Perceptions of Barriers to Dismissal of Poor-Performing Teachers

ERIC Educational Resources Information Center

Dandoy, Jason R.

2012-01-01

The purpose of this study is to determine which factors influence items that school principals consider "barriers" to dismissal of "incompetent" or "poor performing" teachers. This study determines if specific characteristics of schools, principals, or a combination of the two can predict the specific barriers cited…

A mechanism study of sound wave-trapping barriers.

PubMed

Yang, Cheng; Pan, Jie; Cheng, Li

2013-09-01

The performance of a sound barrier is usually degraded if a large reflecting surface is placed on the source side. A wave-trapping barrier (WTB), with its inner surface covered by wedge-shaped structures, has been proposed to confine waves within the area between the barrier and the reflecting surface, and thus improve the performance. In this paper, the deterioration in performance of a conventional sound barrier due to the reflecting surface is first explained in terms of the resonance effect of the trapped modes. At each resonance frequency, a strong and mode-controlled sound field is generated by the noise source both within and in the vicinity outside the region bounded by the sound barrier and the reflecting surface. It is found that the peak sound pressures in the barrier's shadow zone, which correspond to the minimum values in the barrier's insertion loss, are largely determined by the resonance frequencies and by the shapes and losses of the trapped modes. These peak pressures usually result in high sound intensity component impinging normal to the barrier surface near the top. The WTB can alter the sound wave diffraction at the top of the barrier if the wavelengths of the sound wave are comparable or smaller than the dimensions of the wedge. In this case, the modified barrier profile is capable of re-organizing the pressure distribution within the bounded domain and altering the acoustic properties near the top of the sound barrier.

Electronic tunneling through a potential barrier on the surface of a topological insulator

NASA Astrophysics Data System (ADS)

Zhou, Benliang; Zhou, Benhu; Zhou, Guanghui

2016-12-01

We investigate the tunneling transport for electrons on the surface of a topological insulator (TI) through an electrostatic potential barrier. By using the Dirac equation with the continuity conditions for all segments of wave functions at the interfaces between regions inside and outside the barrier, we calculate analytically the transmission probability and conductance for the system. It is demonstrated that, the Klein paradox can also been observed in the system same as in graphene system. Interestingly, the conductance reaches the minimum value when the incident electron energy is equal to the barrier strength. Moreover, with increasing barrier width, the conductance turns up some tunneling oscillation peaks, and larger barrier strength can cause lower conductance, shorter period but larger oscillation amplitude. The oscillation amplitude decreases as the barrier width increases, which is similar as that of the system consisting of the compressive uniaxial strain applied on a TI, but somewhat different from that of graphene system where the oscillation amplitude is a constant. The findings here imply that an electrostatic barrier can greatly influence the electron tunneling transport of the system, and may provide a new way to realize directional filtering of electrons.

Interfacial Chemistry-Induced Modulation of Schottky Barrier Heights: In Situ Measurements of the Pt-Amorphous Indium Gallium Zinc Oxide Interface Using X-ray Photoelectron Spectroscopy.

PubMed

Flynn, Brendan T; Oleksak, Richard P; Thevuthasan, Suntharampillai; Herman, Gregory S

2018-01-31

A method to understand the role of interfacial chemistry on the modulation of Schottky barrier heights for platinum and amorphous indium gallium zinc oxide (a-IGZO) interfaces is demonstrated through thermal processing and background ambient pressure control. In situ X-ray photoelectron spectroscopy was used to characterize the interfacial chemistries that modulate barrier heights in this system. The primary changes were a significant chemical reduction of indium, from In 3+ to In 0 , that occurs during deposition of Pt on to the a-IGZO surface in ultrahigh vacuum. Postannealing and controlling the background ambient O 2 pressure allows further tuning of the reduction of indium and the corresponding Schottky barrier heights from 0.17 to 0.77 eV. Understanding the detailed interfacial chemistries at Pt/a-IGZO interfaces may allow for improved electronic device performance, including Schottky diodes, memristors, and metal-semiconductor field-effect transistors.

Electrical valley filtering in transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Hsieh, Tzu-Chi; Chou, Mei-Yin; Wu, Yu-Shu

2018-03-01

This work investigates the feasibility of electrical valley filtering for holes in transition metal dichalcogenides. We look specifically into the scheme that utilizes a potential barrier to produce valley-dependent tunneling rates, and perform the study with both a k .p -based analytic method and a recursive Green's function-based numerical method. The study yields the transmission coefficient as a function of incident energy and transverse wave vector, for holes going through lateral quantum barriers oriented in either armchair or zigzag directions, in both homogeneous and heterogeneous systems. The main findings are the following: (1) The tunneling current valley polarization increases with increasing barrier width or height; (2) both the valley-orbit interaction and band structure warping contribute to valley-dependent tunneling, with the former contribution being manifest in structures with asymmetric potential barriers, and the latter being orientation dependent and reaching maximum for transmission in the armchair direction; and (3) for transmission ˜0.1 , a tunneling current valley polarization of the order of 10 % can be achieved.

40 CFR 65.112 - Standards: Compressors.

Code of Federal Regulations, 2013 CFR

2013-07-01

... barrier fluid system shall be equipped with a sensor that will detect failure of the seal system, barrier fluid system, or both. Each sensor shall be observed daily or shall be equipped with an alarm unless the... criterion that indicates failure of the seal system, the barrier fluid system, or both. If the sensor...

40 CFR 63.1031 - Compressors standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... service. Each barrier fluid system shall be equipped with a sensor that will detect failure of the seal system, barrier fluid system, or both. Each sensor shall be observed daily or shall be equipped with an... both. If the sensor indicates failure of the seal system, the barrier fluid system, or both based on...

Numerical analysis of three-colour HgCdTe detectors

NASA Astrophysics Data System (ADS)

Jóźwikowski, K.; Rogalski, A.

2007-12-01

The performance of three-colour HgCdTe photovoltaic heterostructure detector is examined theoretically. In comparison with two-colour detectors with two back-to-back junctions, three-colour structure contains an absorber of intermediate wavelength placed between two junctions and electronic barriers are used to isolate this intermediate region. This structure was first proposed by British workers. Three-detector structures with different localizations of separating barriers are analyzed. The calculation results are presented in the form of spatial distributions of bandgap energy and quantum efficiency. Enhanced original computer programs are applied to solve the system of non-linear continuity equations for carriers and Poisson equations. In addition, the numerical analysis includes the dependence of absorption coefficient on Burstein effect as well as interference effects in heterostructure with metallic electrical contacts. It is shown that the performance of the detector is critically dependent on the barrier’s doping level and position in relation to the junction. This behaviour is serious disadvantage of the considered three-colour detector. A small shift of the barrier location and doping level causes serious changes in spectral responsivity.

Factors influencing evidence-based practice in prosthetics and orthotics.

PubMed

Andrysek, Jan; Christensen, James; Dupuis, Annie

2011-03-01

The importance of evidence-based practice is being recognized across a broad range of healthcare disciplines as a means for improving patient outcomes and also efficiently managing healthcare resources. The objective of this work was to obtain information from clinicians about the underlying barriers and facilitators relating to evidence-based practice in prosthetics and orthotics. Cross sectional survey. An internet survey was developed and distributed to 300 prosthetists and orthotists currently practicing in Canada. A principal component factor analysis of the survey results revealed ten primary factors affecting evidence-based practice. These include time constraints, workload and system demands, limited relevant evidence from research, and gaps in skills and knowledge required to perform evidence-based practice. Clinicians value research as a means of improving clinical practice, but they are faced with a number of practical barriers in performing evidence-based practice. This study provides empirical data about the underlying barriers and facilitators relating to evidence-based practice in prosthetics and orthotics. Such data are essential in order to inform those involved in improving existing clinical practices, including educators, professional organizations, and governing bodies.

Developing Cost-Effective Dense Continuous SDC Barrier Layers for SOFCs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Hoang Viet P.; Hardy, John S.; Coyle, Christopher A.

Significantly improved performance during electrochemical testing of a cell with a dense continuous pulsed laser deposited (PLD) samarium doped ceria (SDC) layer spurred investigations into the fabrication of dense continuous SDC barrier layers by means of cost-effective deposition using screen printing which is amenable to industrial production of SOFCs. Many approaches to improve the SDC density have been explored including the use of powder with reduced particle sizes, inks with increased solids loading, and doping with sintering aids (1). In terms of sintering aids, dopants like Mo or binary systems of Mo+Cu or Fe+Co greatly enhance SDC sinterability. In fact,more » adding dopants to a screen printed, prefired, porous SDC layer made it possible to achieve a dense continuous barrier layer atop the YSZ electrolyte without sintering above 1200°C. Although the objective of fabricating a dense continuous layer was achieved, additional studies have been initiated to improve the cell performance. Underlying issues with constrained sintering and dopant-enhanced ceria-zirconia solid solubility are also addressed in this paper.« less

Fission Meter Information Barrier Attribute Measurement System - NA-243 FNI/UKC FY2017 Task 1-2 Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kerr, P. L.; Decman, D.; Prasad, M.

An SNM attribute Information Barrier (IB) system was developed for a 2011 US/UK Exercise. The system was modified and extensively tested in a 2013-2014 US-UK Measurement Campaign. This work demonstrated rapid deployment of an IB system for potential treaty use. The system utilizes an Ortec Fission Meter neutron multiplicity counter and custom computer code. The system demonstrates a proof-of-principle automated Pu-240 mass determination with an information barrier. After a software start command is issued, the system automatically acquires and downloads data, performs an analysis, and displays the results. This system conveys the results of a Pu mass threshold measurements inmore » a way the does not reveal sensitive information. In full IB mode, only the pass/fail result is displayed as a “Mass <= Threshold Amount” or “Mass >= Threshold Amount” as shown in Figure 4. This can easily be adapted to a red/green “lights” display similar to the Detective IB system for Pu isotopics as shown in Figure 6. In test mode, more detailed information is displayed. The code can also read in, analyze, and display results from previously acquired or simulated data. Because the equipment is commercial-off-the-shelf (COTS), the system demonstrates a low-cost short-lead-time technology for treaty SNM attribute measurements. A deployed system will likely require integration of additional authentication and tamper-indicating technologies. This will be discussed for the project in this and future progress reports.« less

Measuring performance of brief alcohol counseling in medical settings:a review of the options and lessons from the Veterans Affairs (VA) health care system.

PubMed

Bradley, Katharine A; Williams, Emily C; Achtmeyer, Carol E; Hawkins, Eric J; Harris, Alex H S; Frey, Madeleine S; Craig, Thomas; Kivlahan, Daniel R

2007-01-01

Brief alcohol counseling is a top US prevention priority but has not been widely implemented. The lack of an easy performance measure for brief alcohol counseling is one important barrier to implementation. The purpose of this report is to outline important issues related to measuring performance of brief alcohol counseling in health care settings. We review the strengths and limitations of several options for measuring performance of brief alcohol counseling and describe three measures of brief alcohol counseling tested in the Veterans Affairs (VA) Health Care System. We conclude that administrative data are not well-suited to measuring performance of brief alcohol counseling. Patient surveys appear to offer the optimal approach currently available for comparing performance of brief alcohol counseling across health care systems, while more options are available for measuring performance within health care systems. Further research is needed in this important area of quality improvement.

'Just doing the best we can': health care providers' perceptions of barriers to providing care to Marshallese patients in Arkansas.

PubMed

McElfish, Pearl A; Chughtai, Almas; Low, Lisa K; Garner, Robert; Purvis, Rachel S

2018-05-04

Marshallese migrating to the United States encounter challenges in accessing health care. Previous literature has investigated Marshallese participants' perceptions of the barriers they face in accessing health care. For this study, health care providers managing the care of Marshallese patients were interviewed to understand the providers' perception of barriers that their Marshallese patients encounter. A qualitative research design was utilized to explore health care providers' perceptions of and experiences with the barriers faced by their Marshallese patients when accessing the US health care system. The primary barriers identified were: (1) economic barriers; (2) communication challenges; (3) difficulty understanding and navigating the western health care system; and (4) structural and system barriers. This study provides insight on the barriers Marshallese patients face in accessing health care as well as the barriers providers face in delivering care to Marshallese patients. A better understanding of these barriers can help health care providers and educators to begin initiating improvements in the delivery of care to Marshallese patients.

[Barriers to the normalization of telemedicine in a healthcare system model based on purchasing of healthcare services using providers' contracts].

PubMed

Roig, Francesc; Saigí, Francesc

2011-01-01

Despite the clear political will to promote telemedicine and the large number of initiatives, the incorporation of this modality in clinical practice remains limited. The objective of this study was to identify the barriers perceived by key professionals who actively participate in the design and implementation of telemedicine in a healthcare system model based on purchasing of healthcare services using providers' contracts. We performed a qualitative study based on data from semi-structured interviews with 17 key informants belonging to distinct Catalan health organizations. The barriers identified were grouped in four areas: technological, organizational, human and economic. The main barriers identified were changes in the healthcare model caused by telemedicine, problems with strategic alignment, resistance to change in the (re)definition of roles, responsibilities and new skills, and lack of a business model that incorporates telemedicine in the services portfolio to ensure its sustainability. In addition to suitable management of change and of the necessary strategic alignment, the definitive normalization of telemedicine in a mixed healthcare model based on purchasing of healthcare services using providers' contracts requires a clear and stable business model that incorporates this modality in the services portfolio and allows healthcare organizations to obtain reimbursement from the payer. 2010 SESPAS. Published by Elsevier Espana. All rights reserved.

The influence of visual characteristics of barriers on railway noise perception.

PubMed

Maffei, Luigi; Masullo, Massimiliano; Aletta, Francesco; Di Gabriele, Maria

2013-02-15

Noise annoyance is considered as the main effect of noise, it is a complex and multifaceted psychological concept dealing with immediate behavioral and evaluative aspects. In the last decades the research has intensely investigated the correlation between noise exposure and noise annoyance, nevertheless recent studies confirm that non-auditory factors influence the noise perception of individuals. In particular audio-video interaction can play a fundamental role. Today Immersive Virtual Reality (IVR) systems allow building laboratory test providing realistic experiences of the surrounding environment to detect more accurate information about the reactions of the local population. Regarding the interventions for environmental noise control the barriers represent the main solution; however some aspects related to their visual characteristic have to be further investigated. This paper presented a case study, where a sample of residents living close to a railway line assessed noise-related aspects for several barriers with different visual characteristics in an IVR laboratory test. In particular, three main factors were analyzed: the barrier type concerning the visibility of the noise source through the screen, the visual aspect of the barrier concerning some aesthetic issues and the noise level at the receiver concerning the acoustic performance of the barrier and the magnitude of the sound source. The main results of the ANOVA analysis showed that for transparent barriers Perceived Loudness and Noise Annoyance were judged lower than for opaque barriers; this difference increased as noise level increased. Copyright © 2012. Published by Elsevier B.V.

Development Status and Performance Comparisons of Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Harder, Bryan

2016-01-01

Environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft turbine engine systems, because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. This paper presents current NASA EBC-CMC development emphases including: the coating composition and processing improvements, laser high heat flux-thermal gradient thermo-mechanical fatigue - environmental testing methodology development, and property evaluations for next generation EBC-CMC systems. EBCs processed with various deposition techniques including Plasma Spray, Electron Beam - Physical Vapor Deposition, and Plasma Spray Physical Vapor Deposition (PS-PVD) will be particularly discussed. The testing results and demonstrations of advanced EBCs-CMCs in complex simulated engine thermal gradient cyclic fatigue, oxidizing-steam and CMAS environments will help provide insights into the coating development strategies to meet long-term engine component durability goals.

Localized saddle-point search and application to temperature-accelerated dynamics

NASA Astrophysics Data System (ADS)

Shim, Yunsic; Callahan, Nathan B.; Amar, Jacques G.

2013-03-01

We present a method for speeding up temperature-accelerated dynamics (TAD) simulations by carrying out a localized saddle-point (LSAD) search. In this method, instead of using the entire system to determine the energy barriers of activated processes, the calculation is localized by only including a small chunk of atoms around the atoms directly involved in the transition. Using this method, we have obtained N-independent scaling for the computational cost of the saddle-point search as a function of system size N. The error arising from localization is analyzed using a variety of model systems, including a variety of activated processes on Ag(100) and Cu(100) surfaces, as well as multiatom moves in Cu radiation damage and metal heteroepitaxial growth. Our results show significantly improved performance of TAD with the LSAD method, for the case of Ag/Ag(100) annealing and Cu/Cu(100) growth, while maintaining a negligibly small error in energy barriers.

Factors Affecting the Delivery, Access, and Use of Interventions to Prevent Malaria in Pregnancy in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

PubMed Central

Hill, Jenny; Hoyt, Jenna; van Eijk, Anna Maria; D'Mello-Guyett, Lauren; ter Kuile, Feiko O.; Steketee, Rick; Smith, Helen; Webster, Jayne

2013-01-01

Background Malaria in pregnancy has important consequences for mother and baby. Coverage with the World Health Organization–recommended prevention strategy for pregnant women in sub-Saharan Africa of intermittent preventive treatment in pregnancy (IPTp) and insecticide-treated nets (ITNs) is low. We conducted a systematic review to explore factors affecting delivery, access, and use of IPTp and ITNs among healthcare providers and women. Methods and Results We searched the Malaria in Pregnancy Library and Global Health Database from 1 January 1990 to 23 April 2013, without language restriction. Data extraction was performed by two investigators independently, and data was appraised for quality and content. Data on barriers and facilitators, and the effect of interventions, were explored using content analysis and narrative synthesis. We conducted a meta-analysis of determinants of IPTp and ITN uptake using random effects models, and performed subgroup analysis to evaluate consistency across interventions and study populations, countries, and enrolment sites. We did not perform a meta-ethnography of qualitative data. Ninety-eight articles were included, of which 20 were intervention studies. Key barriers to the provision of IPTp and ITNs were unclear policy and guidance on IPTp; general healthcare system issues, such as stockouts and user fees; health facility issues stemming from poor organisation, leading to poor quality of care; poor healthcare provider performance, including confusion over the timing of each IPTp dose; and women's poor antenatal attendance, affecting IPTp uptake. Key determinants of IPTp coverage were education, knowledge about malaria/IPTp, socio-economic status, parity, and number and timing of antenatal clinic visits. Key determinants of ITN coverage were employment status, education, knowledge about malaria/ITNs, age, and marital status. Predictors showed regional variations. Conclusions Delivery of ITNs through antenatal clinics presents fewer problems than delivery of IPTp. Many obstacles to IPTp delivery are relatively simple barriers that could be resolved in the short term. Other barriers are more entrenched within the overall healthcare system or socio-economic/cultural contexts, and will require medium- to long-term strategies. Please see later in the article for the Editors' Summary PMID:23935459

Monitoring Local Strain in a Thermal Barrier Coating System Under Thermal Mechanical Gas Turbine Operating Conditions

NASA Astrophysics Data System (ADS)

Manero, Albert; Sofronsky, Stephen; Knipe, Kevin; Meid, Carla; Wischek, Janine; Okasinski, John; Almer, Jonathan; Karlsson, Anette M.; Raghavan, Seetha; Bartsch, Marion

2015-07-01

Advances in aircraft and land-based turbine engines have been increasing the extreme loading conditions on traditional engine components and have incited the need for improved performance with the use of protective coatings. These protective coatings shield the load-bearing super alloy blades from the high-temperature combustion gases by creating a thermal gradient over their thickness. This addition extends the life and performance of blades. A more complete understanding of the behavior, failure mechanics, and life expectancy for turbine blades and their coatings is needed to enhance and validate simulation models. As new thermal-barrier-coated materials and deposition methods are developed, strides to effectively test, evaluate, and prepare the technology for industry deployment are of paramount interest. Coupling the experience and expertise of researchers at the University of Central Florida, The German Aerospace Center, and Cleveland State University with the world-class synchrotron x-ray beam at the Advanced Photon Source in Argonne National Laboratory, the synergistic collaboration has yielded previously unseen measurements to look inside the coating layer system for in situ strain measurements during representative service loading. These findings quantify the in situ strain response on multilayer thermal barrier coatings and shed light on the elastic and nonelastic properties of the layers and the role of mechanical load and internal cooling variations on the response. The article discusses the experimental configuration and development of equipment to perform in situ strain measurements on multilayer thin coatings and provides an overview of the achievements thus far.

Effective Learner-Centered Approach for Teaching an Introductory Digital Systems Course

ERIC Educational Resources Information Center

Debiec, Piotr

2018-01-01

In the Internet era, students have increasingly lost interest in traditional lectures; as a consequence, their learning motivation and exam performance have decreased. The widespread adoption of learner-centered teaching methods that address this issue faces certain barriers, including: 1) the significant faculty effort necessary to prepare…

Lawyers and Legal Advocacy in Juvenile Courts: An Assessment.

ERIC Educational Resources Information Center

Puritz, Patricia; Burrell, Sue; Schwartz, Robert; Soler, Mark; Warboys, Loren

2000-01-01

Evaluates the juvenile justice system focusing on the barriers children encounter when seeking appropriate counsel and the quality of representation. Includes an assessment of the appointment of counsel, pretrial preparation and trial performance, post-trial maneuvers, and appeals. Finds that the most common obstacle is the overwhelming caseloads…

CONSTRUCTION, MONITORING, AND PERFORMANCE OF TWO SOIL LINERS

EPA Science Inventory

A prototype soil liner and a field-scale soil liner were constructed to test whether compacted soil barrier systems could be built to meet the standard set by the U.S. Environmental Protection Agency (EPA) for saturated hydraulic conductivity (< 1 x 10'7 cm/s). In situ ponded inf...

Place Matters in Non-Traditional Migration Areas: Exploring Barriers to Healthcare for Latino Immigrants by Region, Neighborhood, and Community Health Center.

PubMed

Topmiller, Michael; Zhen-Duan, Jenny; Jacquez, Farrah J; Vaughn, Lisa M

2017-12-01

This paper identifies differences in adult Latino immigrant barriers to healthcare in the Cincinnati area in Hamilton County, OH, on three levels: by region, by neighborhood, and by community health center. Secondary data analysis was performed on 439 surveys. Respondents were aggregated by the geographic regions and neighborhoods where they live and by two community health centers where they receive care. Outcome measures included pragmatic and skill barrier indices adapted from the Barriers to Care Questionnaire (BCQ); the pragmatics index consists logistical barriers, including transportation and cost; the skills index is made up of items related to navigating the healthcare system, including communicating with physicians and completing paperwork. The results indicate that immigrant Latinos living in western Cincinnati and northern Hamilton County face significantly higher pragmatic barriers to care, while Latino immigrants going to a community health center in western Cincinnati have significantly fewer pragmatic and skill barriers than immigrants utilizing a nearby community health center. Because healthcare options for undocumented immigrants do not improve with the Affordable Care Act, community health centers will continue to serve as their primary source of care. This is particularly true in non-traditional migration areas, where immigrants tend to be isolated and lack resources. Efforts to improve access to healthcare for immigrant Latinos require place-based approaches that allow for targeted resources to improve care in these locations. This study helps to fill that need by identifying variation in barriers to care on multiple levels and offering strategies to alleviate these barriers.

Near Two-Decade Instrument Performance for Hydrological Monitoring at the Prototype Hanford Barrier

NASA Astrophysics Data System (ADS)

Zhang, Z. F.; Strickland, C. E.; Clayton, R. E.

2012-12-01

Surface barriers have been proposed for use at the Department of Energy's Hanford Site as a means to isolate certain radioactive waste sites that, for reasons of cost or worker safety, may not be exhumed. The Hanford Prototype Barrier was constructed in 1994 using mostly natural materials to demonstrate its long-term performance. The barrier is expected to perform for at least 1000 years by limiting water, plant, animal, and human intrusion and minimizing erosion. Extensive instrumentation is used to monitor the hydrological regime above, within, below, and around the barrier. Specifically, natural precipitation and irrigation are measured with rain gauges, runoff water with a runoff flume, soil water content within the barrier at 12 stations with a neutron probe, a capacitance probe, and time-domain-reflectometry probes, and soil water pressure with gypsum blocks and heat-dissipation-units. Drainage through the barrier and the side slopes is measured with 12 water collection vaults, respectively, for 12 zones. Each drainage vault is equipped with a dosing siphon, a dose counter, a pressure transducer to measure the water level, and a tipping bucket to measure the inflow. During the near two-decade monitoring period, some of the instruments stopped functioning, while others still function normally till present. This presentation will summarize the performance of these instruments. Recommendations for future barrier monitoring will be given.

Exploring Machine Learning Techniques For Dynamic Modeling on Future Exascale Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Shuaiwen; Tallent, Nathan R.; Vishnu, Abhinav

2013-09-23

Future exascale systems must be optimized for both power and performance at scale in order to achieve DOE’s goal of a sustained petaflop within 20 Megawatts by 2022 [1]. Massive parallelism of the future systems combined with complex memory hierarchies will form a barrier to efficient application and architecture design. These challenges are exacerbated with emerging complex architectures such as GPGPUs and Intel Xeon Phi as parallelism increases orders of magnitude and system power consumption can easily triple or quadruple. Therefore, we need techniques that can reduce the search space for optimization, isolate power-performance bottlenecks, identify root causes for software/hardwaremore » inefficiency, and effectively direct runtime scheduling.« less

Thin film encapsulation for flexible AM-OLED: a review

NASA Astrophysics Data System (ADS)

Park, Jin-Seong; Chae, Heeyeop; Chung, Ho Kyoon; In Lee, Sang

2011-03-01

Flexible organic light emitting diode (OLED) will be the ultimate display technology to customers and industries in the near future but the challenges are still being unveiled one by one. Thin-film encapsulation (TFE) technology is the most demanding requirement to prevent water and oxygen permeation into flexible OLED devices. As a polymer substrate does not offer the same barrier performance as glass, the TFE should be developed on both the bottom and top side of the device layers for sufficient lifetimes. This work provides a review of promising thin-film barrier technologies as well as the basic gas diffusion background. Topics include the significance of the device structure, permeation rate measurement, proposed permeation mechanism, and thin-film deposition technologies (Vitex system and atomic layer deposition (ALD)/molecular layer deposition (MLD)) for effective barrier films.

Deployment Efficiency and Barrier Effectiveness Testing of a Temporary Anti-Personnel (TAP) Barrier System.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, David James; Hedrick, Charles D.; Martinez, Ruben

This report documents tests conducted by Sandia National Laboratories (SNL) on behalf of the U.S. Department of State to evaluate a temporary anti-personnel (TAP) barrier system developed by Mitigation Technologies. For this, the SNL Denial and Structural Assessment department developed a test protocol for the evaluation of the TAP barrier system on the basis of deployment efficiency and barrier effectiveness against a riotous/mob attack threat. The test protocol was then executed by SNL personnel and the results of the testing are documented.

Interdisciplinary barriers: An impediment to the effective application of systems engineering

NASA Technical Reports Server (NTRS)

Harrison, E., Jr.

1971-01-01

Interdisciplinary transfer of information and technology does not occur very readily, even for system planners, because of the existence of some very real barriers. These barriers to flow of information and technology between disciplines represent one of the important difficulties associated with the application of systems analysis to many problems. The nature and characteristics of some of these barriers are enumerated and discussed in detail. A number of methodologies and techniques which have been specifically developed to aid in the transfer of technology and information across these interdisciplinary barriers is examined.

System redesign of the immunization supply chain: Experiences from Benin and Mozambique.

PubMed

Prosser, Wendy; Jaillard, Philippe; Assy, Emmanuelle; Brown, Shawn T; Matsinhe, Graça; Dekoun, Mawutondji; Lee, Bruce Y

2017-04-19

Evidence suggests that immunization supply chains are becoming outdated and unable to deliver needed vaccines due to growing populations and new vaccine introductions. Redesigning a supply chain could result in meeting current demands. The Ministries of Health in Benin in Mozambique recognized known barriers to the immunization supply chain and undertook a system redesign to address those barriers. Changes were made to introduce an informed push system while consolidating storage points, introducing transport loops, and increasing human resource capacity for distribution. Evaluations were completed in each country. Evaluation in each country indicated improved performance of the supply chain. The Effective Vaccine Management (EVM) assessment in Benin documented notable improvements in the distribution criteria of the tool, increasing from 40% to 100% at the district level. In Mozambique, results showed reduced stockouts at health facility level from 79% at baseline to less than 1% at endline. Coverage rates of DTP3 also increased from 68.9% to 92.8%. Benin and Mozambique are undertaking system redesign in order to respond to constraints identified in the vaccine supply chain. Results and learnings show improvements in supply chain performance and make a strong case for system redesign. These countries demonstrate the feasibility of system redesign for other countries considering how to address outdated supply chains. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Strategies for Enhanced Drug Delivery to the Central Nervous System

PubMed Central

Dwibhashyam, V. S. N. M.; Nagappa, A. N.

2008-01-01

Treating central nervous system diseases is very challenging because of the presence of a variety of formidable obstacles that impede drug delivery. Physiological barriers like the blood-brain barrier and blood-cerebrospinal fluid barrier as well as various efflux transporter proteins make the entry of drugs into the central nervous system very difficult. The present review provides a brief account of the blood brain barrier, the P-glycoprotein efflux and various strategies for enhancing drug delivery to the central nervous system. PMID:20046703

Design of noise barrier inspection system for high-speed railway

NASA Astrophysics Data System (ADS)

Liu, Bingqian; Shao, Shuangyun; Feng, Qibo; Ma, Le; Cholryong, Kim

2016-10-01

The damage of noise barriers will highly reduce the transportation safety of the high-speed railway. In this paper, an online inspection system of noise barrier based on laser vision for the safety of high-speed railway is proposed. The inspection system, mainly consisted of a fast camera and a line laser, installed in the first carriage of the high-speed CIT(Composited Inspection Train).A Laser line was projected on the surface of the noise barriers and the images of the light line were received by the camera while the train is running at high speed. The distance between the inspection system and the noise barrier can be obtained based on laser triangulation principle. The results of field tests show that the proposed system can meet the need of high speed and high accuracy to get the contour distortion of the noise barriers.

Evolution of the Varrier autostereoscopic VR display: 2001-2007

NASA Astrophysics Data System (ADS)

Peterka, Tom; Kooima, Robert L.; Girado, Javier I.; Ge, Jinghua; Sandin, Daniel J.; DeFanti, Thomas A.

2007-02-01

Autostereoscopy (AS) is an increasingly valuable virtual reality (VR) display technology; indeed, the IS&T / SPIE Electronic Imaging Conference has seen rapid growth in the number and scope of AS papers in recent years. The first Varrier paper appeared at SPIE in 2001, and much has changed since then. What began as a single-panel prototype has grown to a full scale VR autostereo display system, with a variety of form factors, features, and options. Varrier is a barrier strip AS display system that qualifies as a true VR display, offering a head-tracked ortho-stereo first person interactive VR experience without the need for glasses or other gear to be worn by the user. Since Varrier's inception, new algorithmic and systemic developments have produced performance and quality improvements. Visual acuity has increased by a factor of 1.4X with new fine-resolution barrier strip linescreens and computational algorithms that support variable sub-pixel resolutions. Performance has improved by a factor of 3X using a new GPU shader-based sub-pixel algorithm that accomplishes in one pass what previously required three passes. The Varrier modulation algorithm that began as a computationally expensive task is now no more costly than conventional stereoscopic rendering. Interactive rendering rates of 60 Hz are now possible in Varrier for complex scene geometry on the order of 100K vertices, and performance is GPU bound, hence it is expected to continue improving with graphics card enhancements. Head tracking is accomplished with a neural network camera-based tracking system developed at EVL for Varrier. Multiple cameras capture subjects at 120 Hz and the neural network recognizes known faces from a database and tracks them in 3D space. New faces are trained and added to the database in a matter of minutes, and accuracy is comparable to commercially available tracking systems. Varrier supports a variety of VR applications, including visualization of polygonal, ray traced, and volume rendered data. Both AS movie playback of pre-rendered stereo frames and interactive manipulation of 3D models are supported. Local as well as distributed computation is employed in various applications. Long-distance collaboration has been demonstrated with AS teleconferencing in Varrier. A variety of application domains such as art, medicine, and science have been exhibited, and Varrier exists in a variety of form factors from large tiled installations to smaller desktop forms to fit a variety of space and budget constraints. Newest developments include the use of a dynamic parallax barrier that affords features that were inconceivable with a static barrier.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hiratsuka, Tatsumasa; Tanaka, Hideki, E-mail: tanaka@cheme.kyoto-u.ac.jp; Miyahara, Minoru T., E-mail: miyahara@cheme.kyoto-u.ac.jp

Capillary condensation in the regime of developing hysteresis occurs at a vapor pressure, P{sub cond}, that is less than that of the vapor-like spinodal. This is because the energy barrier for the vapor-liquid transition from a metastable state at P{sub cond} becomes equal to the energy fluctuation of the system; however, a detailed mechanism of the spontaneous transition has not been acquired even through extensive experimental and simulation studies. We therefore construct accurate atomistic silica mesopore models for MCM-41 and perform molecular simulations (gauge cell Monte Carlo and grand canonical Monte Carlo) for argon adsorption on the models at subcriticalmore » temperatures. A careful comparison between the simulation and experiment reveals that the energy barrier for the capillary condensation has a critical dimensionless value, W{sub c}{sup *} = 0.175, which corresponds to the thermal fluctuation of the system and depends neither on the mesopore size nor on the temperature. We show that the critical energy barrier W{sub c}{sup *} controls the capillary condensation pressure P{sub cond} and also determines a boundary between the reversible condensation/evaporation regime and the developing hysteresis regime.« less

Research notes : time to clean up those barrier markers.

DOT National Transportation Integrated Search

1999-07-01

In February 1997, ODOT Construction installed seven types of barrier markers to investigate short-term performance. The barrier markers are typically installed on the top of concrete barriers or other delineators to visually enhance the alignment. Th...

Fusion cross sections for reactions involving medium and heavy nucleus-nucleus systems

NASA Astrophysics Data System (ADS)

Atta, Debasis; Basu, D. N.

2014-12-01

Existing data on near-barrier fusion excitation functions of medium and heavy nucleus-nucleus systems have been analyzed by using a simple diffused-barrier formula derived assuming the Gaussian shape of the barrier-height distributions. The fusion cross section is obtained by folding the Gaussian barrier distribution with the classical expression for the fusion cross section for a fixed barrier. The energy dependence of the fusion cross section, thus obtained, provides good description to the existing data on near-barrier fusion and capture excitation functions for medium and heavy nucleus-nucleus systems. The theoretical values for the parameters of the barrier distribution are estimated which can be used for fusion or capture cross-section predictions that are especially important for planning experiments for synthesizing new superheavy elements.

Method of recognizing the high-speed railway noise barriers based on the distance image

NASA Astrophysics Data System (ADS)

Ma, Le; Shao, Shuangyun; Feng, Qibo; Liu, Bingqian; Kim, Chol Ryong

2016-10-01

The damage or lack of the noise barriers is one of the important hidden troubles endangering the safety of high-speed railway. In order to obtain the vibration information of the noise barriers, the online detection systems based on laser vision were proposed. The systems capture images of the laser stripe on the noise barriers and export data files containing distance information between the detection systems on the train and the noise barriers. The vibration status or damage of the noise barriers can be estimated depending on the distance information. In this paper, we focused on the method of separating the area of noise barrier from the background automatically. The test results showed that the proposed method is in good efficiency and accuracy.

Analytical investigation of thermal barrier coatings on advanced power generation gas turbines

NASA Technical Reports Server (NTRS)

Amos, D. J.

1977-01-01

An analytical investigation of present and advanced gas turbine power generation cycles incorporating thermal barrier turbine component coatings was performed. Approximately 50 parametric points considering simple, recuperated, and combined cycles (including gasification) with gas turbine inlet temperatures from current levels through 1644K (2500 F) were evaluated. The results indicated that thermal barriers would be an attractive means to improve performance and reduce cost of electricity for these cycles. A recommended thermal barrier development program has been defined.

Measured airtightness of 24 detached houses over periods of up to three years

DOE Office of Scientific and Technical Information (OSTI.GOV)

Proskiw, G.

1995-09-01

Regular airtightness tests were performed on 24 new houses, over periods of up to three years, to evaluate their air barrier systems and to search for evidence, air barrier degradation. Ten of the houses were constructed with polyethylene air barriers while the remaining 14 used an early version of the Airtight Drywall Approach (ADA). The 24 project houses were architecturally similar and of approximately equal size and general layout; stucco was the predominate exterior wall finish. All were exposed to similar terrain shielding. The study found that the airtightness of the polyethylene air barrier houses remained stable over their respectivemore » monitoring periods. Although two of the ten houses demonstrated possible, albeit slight, evidence of airtightness degradation, the magnitude of these changes was small and judged not to be of practical significance. With respect to the critical issue of air barrier degradation, no evidence could be found to indicate polyethylene is unsuited for use as an air barrier material in residential construction. For example, all but one of the polyethylene houses met the airtightness requirements of the Canadian R-2000 Standard for energy efficient housing at the end of their monitoring periods. The study found that the airtightness of the 14 ADA houses also remained stable over their monitoring periods. Although six of the 14 houses displayed possible, but slight, evidence of airtightness degradation, the magnitude of the changes was small and not of practical significance. It was concluded that no evidence could be found to indicate that the ADA system is unsuited for use in residential construction. All 14 ADA houses met the airtightness requirements of the R-2000 Program at the end of their respective monitoring periods.« less

Sensor System Fo4r Buried Waste Containment Sites

DOEpatents

Smith, Ann Marie; Gardner, Bradley M.; Kostelnik, Kevin M.; Partin, Judy K.; Lancaster, Gregory D.; Pfeifer, Mary Catherine

2003-11-18

A sensor system for a buried waste containment site having a bottom wall barrier and sidewall barriers, for containing hazardous waste. The sensor system includes one or more sensor devices disposed in one or more of the barriers for detecting a physical parameter either of the barrier itself or of the physical condition of the surrounding soils and buried waste, and for producing a signal representing the physical parameter detected. Also included is a signal processor for receiving signals produced by the sensor device and for developing information identifying the physical parameter detected, either for sounding an alarm, displaying a graphic representation of a physical parameter detected on a viewing screen and/or a hard copy printout. The sensor devices may be deployed in or adjacent the barriers at the same time the barriers are deployed and may be adapted to detect strain or cracking in the barriers, leakage of radiation through the barriers, the presence and leaking through the barriers of volatile organic compounds, or similar physical conditions.

Sensor system for buried waste containment sites

DOEpatents

Smith, Ann Marie; Gardner, Bradley M.; Kostelnik, Kevin M.; Partin, Judy K.; Lancaster, Gregory D.; Pfeifer, May Catherine

2000-01-01

A sensor system is disclosed for a buried waste containment site having a bottom wall barrier and/or sidewall barriers, for containing hazardous waste. The sensor system includes one or more sensor devices disposed in one or more of the barriers for detecting a physical parameter either of the barrier itself or of the physical condition of the surrounding soils and buried waste, and for producing a signal representing the physical parameter detected. Also included is a signal processor for receiving signals produced by the sensor device and for developing information identifying the physical parameter detected, either for sounding an alarm, displaying a graphic representation of a physical parameter detected on a viewing screen and/or a hard copy printout. The sensor devices may be deployed in or adjacent the barriers at the same time the barriers are deployed and may be adapted to detect strain or cracking in the barriers, leakage of radiation through the barriers, the presence and leaking through the barriers of volatile organic compounds, or similar physical conditions.

Sensor System Fo4r Buried Waste Containment Sites

DOEpatents

Smith, Ann Marie; Gardner, Bradley M.; Kostelnik, Kevin M.; Partin, Judy K.; Lancaster, Gregory D.; Pfeifer, Mary Catherine

2005-09-27

A sensor system for a buried waste containment site having a bottom wall barrier and/or sidewall barriers, for containing hazardous waste. The sensor system includes one or more sensor devices disposed in one or more of the barriers for detecting a physical parameter either of the barrier itself or of the physical condition of the surrounding soils and buried waste, and for producing a signal representing the physical parameter detected. Also included is a signal processor for receiving signals produced by the sensor device and for developing information identifying the physical parameter detected, either for sounding an alarm, displaying a graphic representation of a physical parameter detected on a viewing screen and/or a hard copy printout. The sensor devices may be deployed in or adjacent the barriers at the same time the barriers are deployed and may be adapted to detect strain or cracking in the barriers, leakage of radiation through the barriers, the presence and leaking through the barriers of volatile organic compounds, or similar physical conditions.

Mitigation of explosions of hydrogen-air mixtures using bulk materials and aqueous foam

NASA Astrophysics Data System (ADS)

Medvedev, S. P.; Khomik, S. V.; Mikhalkin, V. N.; Ivantsov, A. N.; Agafonov, G. L.; Cherepanov, A. A.; Cherepanova, T. T.; Betev, A. S.

2018-01-01

The objective of this work is to determine experimentally the effectiveness of protective barriers under conditions when blast waves are generated during premixed hydrogen- air combustion in various regimes. Experiments are conducted in a vertical tube having a diameter of 54 mm and a length of up to 2 m. Blast loads are produced by acceleration of premixed hydrogen-air flames in the tube with ring obstacles. Comparative tests are performed between protection barriers made of bulk materials with different densities and aqueous foams with different expansion ratios. It is demonstrated that the degree of blast load attenuation by an aqueous foam barrier increases with decreasing molecular weight of the filling gas and increasing density (decreasing expansion ratio) of the foam. An Aerosil barrier three times thicker than a titanium-dioxide one is found to have a similar attenuating effect on blast action. However, the mass per unit area of an Aerosil barrier is lower than titanium dioxide by a factor of 6 and is comparable to foam. The observed dependence of blast load attenuation on parameters of bulk materials and aqueous foams must be taken into account in systems designed to mitigate the consequences of accidental hydrogen release and combustion.

Fundamental Materials Studies for Advanced High Power Microwave and Terahertz Vacuum Electronic Radiation Sources

DTIC Science & Technology

2014-12-10

AFRL-OSR-VA-TR-2014-0359 Fundamental Materials Studies for Advanced High Power Microwave and Terahertz John Booske UNIVERSITY OF WISCONSIN SYSTEM...12-2014 Final Technical Performance Report October 1, 2011 - September 30, 2014 Fundamental Materials Studies for Advanced High Power Microwave and...emission-barrier scandate cathodes and identify related, alternative cathode materials systems for advanced vacuum electronic cathodes for high power THz

Proposal of the confinement strategy of radioactive and hazardous materials for the European DEMO

NASA Astrophysics Data System (ADS)

Jin, X. Z.; Carloni, D.; Stieglitz, R.; Ciattaglia, S.; Johnston, J.; Taylor, N.

2017-04-01

Confinement of radioactive and hazardous materials is one of the fundamental safety functions in a nuclear fusion facility, which has to limit the mobilisation and dispersion of sources and hazards during normal, abnormal and accidental situations. In a first step energy sources and radioactive source have been assessed for a conceptual DEMO configuration. The confinement study for the European DEMO has been investigated for the main systems at the plant breakdown structure (PBS) level 1 taking a bottom-up approach. Based on the identification of the systems possessing a confinement function, a confinement strategy has been proposed, in which DEMO confinement systems and barriers have been defined. In addition, confinement for the maintenance has been issued as well. The assignment of confinement barriers to the identified sources under abnormal and accidental conditions has been performed, and the DEMO main safety systems have been proposed as well. Finally, confinement related open issues have been pointed out, which need to be resolved in parallel with DEMO development.

Barriers and facilitators to adoption of soft copy interpretation from the user perspective: Lessons learned from filmless radiology for slideless pathology

PubMed Central

Patterson, Emily S.; Rayo, Mike; Gill, Carolina; Gurcan, Metin N.

2011-01-01

Background: Adoption of digital images for pathological specimens has been slower than adoption of digital images in radiology, despite a number of anticipated advantages for digital images in pathology. In this paper, we explore the factors that might explain this slower rate of adoption. Materials and Method: Semi-structured interviews on barriers and facilitators to the adoption of digital images were conducted with two radiologists, three pathologists, and one pathologist's assistant. Results: Barriers and facilitators to adoption of digital images were reported in the areas of performance, workflow-efficiency, infrastructure, integration with other software, and exposure to digital images. The primary difference between the settings was that performance with the use of digital images as compared to the traditional method was perceived to be higher in radiology and lower in pathology. Additionally, exposure to digital images was higher in radiology than pathology, with some radiologists exclusively having been trained and/or practicing with digital images. The integration of digital images both improved and reduced efficiency in routine and non-routine workflow patterns in both settings, and was variable across the different organizations. A comparison of these findings with prior research on adoption of other health information technologies suggests that the barriers to adoption of digital images in pathology are relatively tractable. Conclusions: Improving performance using digital images in pathology would likely accelerate adoption of innovative technologies that are facilitated by the use of digital images, such as electronic imaging databases, electronic health records, double reading for challenging cases, and computer-aided diagnostic systems. PMID:21383925

7 CFR 1955.56 - Real property located in Coastal Barrier Resources System (CBRS).

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 14 2010-01-01 2009-01-01 true Real property located in Coastal Barrier Resources... Management of Property § 1955.56 Real property located in Coastal Barrier Resources System (CBRS). (a... Coastal Barrier Resources Act (CBRA). Pursuant to the requirements of the CBRA, and except as specified in...

The Drosophila blood-brain barrier: development and function of a glial endothelium.

PubMed

Limmer, Stefanie; Weiler, Astrid; Volkenhoff, Anne; Babatz, Felix; Klämbt, Christian

2014-01-01

The efficacy of neuronal function requires a well-balanced extracellular ion homeostasis and a steady supply with nutrients and metabolites. Therefore, all organisms equipped with a complex nervous system developed a so-called blood-brain barrier, protecting it from an uncontrolled entry of solutes, metabolites or pathogens. In higher vertebrates, this diffusion barrier is established by polarized endothelial cells that form extensive tight junctions, whereas in lower vertebrates and invertebrates the blood-brain barrier is exclusively formed by glial cells. Here, we review the development and function of the glial blood-brain barrier of Drosophila melanogaster. In the Drosophila nervous system, at least seven morphologically distinct glial cell classes can be distinguished. Two of these glial classes form the blood-brain barrier. Perineurial glial cells participate in nutrient uptake and establish a first diffusion barrier. The subperineurial glial (SPG) cells form septate junctions, which block paracellular diffusion and thus seal the nervous system from the hemolymph. We summarize the molecular basis of septate junction formation and address the different transport systems expressed by the blood-brain barrier forming glial cells.

Highway renewable energy : photovoltaic noise barriers

DOT National Transportation Integrated Search

2017-07-01

Highway photovoltaic noise barriers (PVNBs) represent the combination of noise barrier systems and photovoltaic systems in order to mitigate traffic noise while simultaneously producing renewable energy. First deployed in Switzerland in 1989, PVNBs a...

Improved performance of In0.83Ga0.17As/InP photodetectors through modifying the position of In0.66Ga0.34As/InAs superlattice electron barrier

NASA Astrophysics Data System (ADS)

Shi, Yan-hui; Zhang, Yong-gang; Ma, Ying-jie; Gu, Yi; Chen, Xing-you; Gong, Qian; Du, Ben; Zhang, Jian; Zhu, Yi

2018-03-01

The performance of wavelength extended In0.83Ga0.17As/InP photodetectors has been improved notably through modifying the position of electron barriers in absorption layer. In order to fully utilize the diffusion component of the photocurrent, the In0.66Ga0.34As/InAs superlattice electron barrier is moved to the edge of the depletion region. Enhanced peak photo responsivity up to 0.84 A/W is realized, which raises 24% compared to that of a reference detector with the superlattice barrier in the middle of the absorber. The dark current slightly increases by 25% at room temperature while decreases by more than an order of magnitude at 150 K, resulting in about 10% or more than twofold improvements for the detectivity, respectively. The results suggest that optimized barrier position is a necessity for barrier-type photodetectors to achieve better performances.

The blood-brain barrier: an engineering perspective

PubMed Central

Wong, Andrew D.; Ye, Mao; Levy, Amanda F.; Rothstein, Jeffrey D.; Bergles, Dwight E.; Searson, Peter C.

2013-01-01

It has been more than 100 years since Paul Ehrlich reported that various water-soluble dyes injected into the circulation did not enter the brain. Since Ehrlich's first experiments, only a small number of molecules, such as alcohol and caffeine have been found to cross the blood-brain barrier, and this selective permeability remains the major roadblock to treatment of many central nervous system diseases. At the same time, many central nervous system diseases are associated with disruption of the blood-brain barrier that can lead to changes in permeability, modulation of immune cell transport, and trafficking of pathogens into the brain. Therefore, advances in our understanding of the structure and function of the blood-brain barrier are key to developing effective treatments for a wide range of central nervous system diseases. Over the past 10 years it has become recognized that the blood-brain barrier is a complex, dynamic system that involves biomechanical and biochemical signaling between the vascular system and the brain. Here we reconstruct the structure, function, and transport properties of the blood-brain barrier from an engineering perspective. New insight into the physics of the blood-brain barrier could ultimately lead to clinical advances in the treatment of central nervous system diseases. PMID:24009582

Evaluating the effect of a web-based quality improvement system with feedback and outreach visits on guideline concordance in the field of cardiac rehabilitation: rationale and study protocol.

PubMed

van Engen-Verheul, Mariëtte M; de Keizer, Nicolette F; van der Veer, Sabine N; Kemps, Hareld M C; Scholte op Reimer, Wilma J M; Jaspers, Monique W M; Peek, Niels

2014-12-31

Implementation of clinical practice guidelines into daily care is hampered by a variety of barriers related to professional knowledge and collaboration in teams and organizations. To improve guideline concordance by changing the clinical decision-making behavior of professionals, computerized decision support (CDS) has been shown to be one of the most effective instruments. However, to address barriers at the organizational level, additional interventions are needed. Continuous monitoring and systematic improvement of quality are increasingly used to achieve change at this level in complex health care systems. The study aims to assess the effectiveness of a web-based quality improvement (QI) system with indicator-based performance feedback and educational outreach visits to overcome organizational barriers for guideline concordance in multidisciplinary teams in the field of cardiac rehabilitation (CR). A multicenter cluster-randomized trial with a balanced incomplete block design will be conducted in 18 Dutch CR clinics using an electronic patient record with CDS at the point of care. The intervention consists of (i) periodic performance feedback on quality indicators for CR and (ii) educational outreach visits to support local multidisciplinary QI teams focussing on systematically improving the care they provide. The intervention is supported by a web-based system which provides an overview of the feedback and facilitates development and monitoring of local QI plans. The primary outcome will be concordance to national CR guidelines with respect to the CR needs assessment and therapy indication procedure. Secondary outcomes are changes in performance of CR clinics as measured by structure, process and outcome indicators, and changes in practice variation on these indicators. We will also conduct a qualitative process evaluation (concept-mapping methodology) to assess experiences from participating CR clinics and to gain insight into factors which influence the implementation of the intervention. To our knowledge, this will be the first study to evaluate the effect of providing performance feedback with a web-based system that incorporates underlying QI concepts. The results may contribute to improving CR in the Netherlands, increasing knowledge on facilitators of guideline implementation in multidisciplinary health care teams and identifying success factors of multifaceted feedback interventions. NTR3251.

Volumetric analysis of a New England barrier system using ground-penetrating-radar and coring techniques

USGS Publications Warehouse

Van Heteren, S.; FitzGerald, D.M.; Barber, D.C.; Kelley, J.T.; Belknap, D.F.

1996-01-01

Ground-penetrating-radar (GPR) profiles calibrated with core data allow accurate assessments of coastal barrier volumes. We applied this procedure successfully to the barrier system along Saco Bay, Maine (USA), as part of a sediment-budget study that focused on present-day sand volumes in various coastal, shoreface, and inner-shelf lith-osomes, and on sand fluxes that have affected the volume or distribution of sand in these sediment bodies through time. On GPR profiles, the components of the barrier lithosome are readily differentiated from other facies, except where the radar signal is attenuated by brackish or salty groundwater. Significant differences between dielectric properties of the barrier lithosome and other units commonly result in strong boundary reflectors. The mostly sandy barrier sediments allow deep penetration of GPR waves, in contrast to finer-grained strata and till-covered bedrock. Within the Saco Bay barrier system, 22 ??3 x 106 m3 of sediment are unevenly distributed. Two-thirds of the total barrier volume is contained within the northern and southern ends of the study area, in the Pine Point spit and the Ferry Beach/Goosefare complex, respectively. The central area around Old Orchard Beach is locally covered by only a thin veneer of barrier sand, averaging <3 m, that unconformably overlies shallow pre-Holocene facies. The prominence of barrier-spit facies and the distribution pattern of back-barrier sediments indicate that a high degree of segmentation, governed by antecedent topography, has affected the development of the Saco Bay barrier system. The present-day configuration of the barrier and back-barrier region along Saco Bay, however, conceals much of its early compartmentalized character.

A qualitative analysis of interprofessional healthcare team members' perceptions of patient barriers to healthcare engagement.

PubMed

Powell, Rhea E; Doty, Amanda; Casten, Robin J; Rovner, Barry W; Rising, Kristin L

2016-09-20

Healthcare systems increasingly engage interprofessional healthcare team members such as case managers, social workers, and community health workers to work directly with patients and improve population health. This study elicited perspectives of interprofessional healthcare team members regarding patient barriers to health and suggestions to address these barriers. This is a qualitative study employing focus groups and semi-structured interviews with 39 interprofessional healthcare team members in Philadelphia to elicit perceptions of patients' needs and experiences with the health system, and suggestions for positioning health care systems to better serve patients. Themes were identified using a content analysis approach. Three focus groups and 21 interviews were conducted with 26 hospital-based and 13 ambulatory-based participants. Three domains emerged to characterize barriers to care: social determinants, health system factors, and patient trust in the health system. Social determinants included insurance and financial shortcomings, mental health and substance abuse issues, housing and transportation-related limitations, and unpredictability associated with living in poverty. Suggestions for addressing these barriers included increased financial assistance from the health system, and building a workforce to address these determinants directly. Health care system factors included poor care coordination, inadequate communication of hospital discharge instructions, and difficulty navigating complex systems. Suggestions for addressing these barriers included enhanced communication between care sites, patient-centered scheduling, and improved patient education especially in discharge planning. Finally, factors related to patient trust of the health system emerged. Participants reported that patients are often intimidated by the health system, mistrusting of physicians, and fearful of receiving a serious diagnosis or prognosis. A suggestion for mitigating these issues was increased visibility of the health system within communities to foster trust and help providers gain a better understanding of unique community needs. This work explored interprofessional healthcare team members' perceptions of patient barriers to healthcare engagement. Participants identified barriers related to social determinants of health, complex system organization, and patient mistrust of the health system. Participants offered concrete suggestions to address these barriers, with suggestions supporting current healthcare reform efforts that aim at addressing social determinants and improving health system coordination and adding new insight into how systems might work to improve patient and community trust.

Subsurface materials management and containment system

DOEpatents

Nickelson, Reva A.; Richardson, John G.; Kosteinik, Kevin M.; Sloan, Paul A.

2004-07-06

Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

Subsurface materials management and containment system

DOEpatents

Nickelson, Reva A.; Richardson, John G.; Kostelnik, Kevin M.; Sloan, Paul A.

2006-10-17

Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

Morphology and stratigraphy of small barrier-lagoon systems in Maine

USGS Publications Warehouse

Duffy, W.; Belknap, D.F.; Kelley, J.T.

1989-01-01

The coast of Maine contains over 200 individual barrier-lagoon systems, most quite small, with an aggregate length of nearly 100 km. Although they represent less than 5% of the tidally influenced coastline of Maine, they are widely distributed and occur in a variety of dynamic regimes and physiographic regions. Their morphology and backbarrier stratigraphy are different from better studied coastal plain systems, and provide important clues to the Holocene evolution of the Maine coast. In a study of geomorphic form and backbarrier stratigraphy, inlet processes and Holocene sea-level rise have been identified as the principal controls on coarse-grained barrier stratigraphy. Barriers in Maine are found in five distinct geomorphic forms, identified herein as: barrier spits, pocket barriers, double tombolos, cuspate barriers and looped barriers. The few long sandy beaches in southwestern Maine are mostly barrier spits. The remainder of the barrier types is composed primarily of gravel or mixed sand and gravel. The barriers protect a variety of backbarrier environments: fresh and brackish ponds, lagoons and fresh- and saltwater marshes. The barriers may or may not have inlets. Normal wave action, coarse-grain size and a deeply embayed coast result in barriers with steep, reflective profiles several meters above MHW. Occasional storm events completely wash over the barriers, building steep, lobate gravel fans along their landward margin. Few, if any, extensive storm layers are recognized as extending into the distal backbarrier environments, however. During sea-level rise and landward barrier retreat, this abrupt, storm-generated transition zone inters the backbarrier sediments. Statistical comparisons of barrier morphology, location and backbarrier environment type with backbarrier stratigraphy show that Holocene backbarrier stratigraphy is best predicted by the modern backbarrier environment type. This, in turn, is influenced most by the absence or presence, and long-term stability or instability of a tidal inlet. Geomorphic barrier form and location in coastal geomorphic compartments show little or no correlation with backbarrier stratigraphy. In contrast to previous classifications of barrier-lagoon systems based primarily on sandy, coastal plain examples, in Maine the shape or origin of the backbarrier system is relatively unimportant. The presence or absence of a tidal inlet is of paramount importance in shaping the Holocene stratigraphy of the backbarrier region. ?? 1989.

Barriers to the utilization of synthetic fuels for transportation

NASA Technical Reports Server (NTRS)

Parker, H. W.; Reilly, M. J.

1981-01-01

The principal types of engines for transportation uses are reviewed and the specifications for conventional fuels are compared with specifications for synthetic fuels. Synfuel processes nearing the commercialization phase are reviewed. The barriers to using synfuels can be classified into four groups: technical, such as the uncertainty that a new engine design can satisfy the desired performance criteria; environmental, such as the risk that the engine emissions cannot meet the applicable environmental standards; economic, including the cost of using a synfuel relative to conventional transportation fuels; and market, involving market penetration by offering new engines, establishing new distribution systems and/or changing user expectations.

Providers' perceptions of the implementation of a performance measurement system for substance abuse treatment: A process evaluation of the Service Quality Measures initiative.

PubMed

Myers, Bronwyn; Williams, Petal Petersen; Johnson, Kim; Govender, Rajen; Manderscheid, Ron; Koch, J Randy

2016-02-22

In South Africa, concerns exist about the quality of substance abuse treatment. We developed a performance measurement system, known as the Service Quality Measures (SQM) initiative, to monitor the quality of treatment and assess efforts to improve quality of care. In 2014, the SQM system was implemented at six treatment sites to evaluate how implementation protocols could be improved in preparation for wider roll-out. To describe providers' perceptions of the feasibility and acceptability of implementing the SQM system, including barriers to and facilitators of implementation. We conducted 15 in-depth interviews (IDIs) with treatment providers from six treatment sites (two sites in KwaZulu-Natal and four in the Western Cape). Providers were asked about their experiences in implementing the system, the perceived feasibility of the system, and barriers to implementation. All IDIs were audio-recorded and transcribed verbatim. A framework approach was used to analyse the data. Providers reported that the SQM system was feasible to implement and acceptable to patients and providers. Issues identified through the IDIs included a perceived lack of clarity about sequencing of key elements in the implementation of the SQM system, questions on integration of the system into clinical care pathways, difficulties in tracking patients through the system, and concerns about maximising patient participation in the process. Findings suggest that the SQM system is feasible to implement and acceptable to providers, but that some refinements to the implementation protocols are needed to maximise patient participation and the likelihood of sustained implementation.

Overcoming barriers to ITS : lessons from other technologies : final task C report : models ff public and private participation in ATMS/ATIS

DOT National Transportation Integrated Search

1997-09-01

This report documents the results of a Federal Highway ADministration (FHWA) study of the agency's Highqay Performance Monitoring System (HPMS). The purpose of this study was to assist FHWA in conducting a comprehensive review of the HPMS, designed t...

Gender Inequality and Research Performance: Moving beyond Individual-Meritocratic Explanations of Academic Advancement

ERIC Educational Resources Information Center

Nielsen, Mathias Wullum

2016-01-01

Academic debates addressing the persistent gender gap in science reveal considerable contestation of the relevance and extent of the problem. Particular attention has been given to the question of whether women's high attrition rates should be ascribed to the structural and cultural barriers inherent to the academic system or instead…

Finite Element Evaluation of Two Retrofit Options to Enhance the Performance of Cable Media Barriers.

DOT National Transportation Integrated Search

2009-06-30

This report summarizes the finite element modeling and simulation efforts on evaluating the performance of cable median barriers including the current and several proposed retrofit designs. It also synthesizes a literature review of the performance e...

Do detour tasks provide accurate assays of inhibitory control?

PubMed Central

Whiteside, Mark A.; Laker, Philippa R.; Beardsworth, Christine E.

2018-01-01

Transparent Cylinder and Barrier tasks are used to purportedly assess inhibitory control in a variety of animals. However, we suspect that performances on these detour tasks are influenced by non-cognitive traits, which may result in inaccurate assays of inhibitory control. We therefore reared pheasants under standardized conditions and presented each bird with two sets of similar tasks commonly used to measure inhibitory control. We recorded the number of times subjects incorrectly attempted to access a reward through transparent barriers, and their latencies to solve each task. Such measures are commonly used to infer the differential expression of inhibitory control. We found little evidence that their performances were consistent across the two different Putative Inhibitory Control Tasks (PICTs). Improvements in performance across trials showed that pheasants learned the affordances of each specific task. Critically, prior experience of transparent tasks, either Barrier or Cylinder, also improved subsequent inhibitory control performance on a novel task, suggesting that they also learned the general properties of transparent obstacles. Individual measures of persistence, assayed in a third task, were positively related to their frequency of incorrect attempts to solve the transparent inhibitory control tasks. Neophobia, Sex and Body Condition had no influence on individual performance. Contrary to previous studies of primates, pheasants with poor performance on PICTs had a wider dietary breadth assayed using a free-choice task. Our results demonstrate that in systems or taxa where prior experience and differences in development cannot be accounted for, individual differences in performance on commonly used detour-dependent PICTS may reveal more about an individual's prior experience of transparent objects, or their motivation to acquire food, than providing a reliable measure of their inhibitory control. PMID:29593115

Corrosion resistant thermal barrier coating. [protecting gas turbines and other engine parts

NASA Technical Reports Server (NTRS)

Levine, S. R.; Miller, R. A.; Hodge, P. E. (Inventor)

1981-01-01

A thermal barrier coating system for protecting metal surfaces at high temperature in normally corrosive environments is described. The thermal barrier coating system includes a metal alloy bond coating, the alloy containing nickel, cobalt, iron, or a combination of these metals. The system further includes a corrosion resistant thermal barrier oxide coating containing at least one alkaline earth silicate. The preferred oxides are calcium silicate, barium silicate, magnesium silicate, or combinations of these silicates.

Real-time monitoring of human blood-brain barrier disruption

PubMed Central

Kiviniemi, Vesa; Korhonen, Vesa; Kortelainen, Jukka; Rytky, Seppo; Keinänen, Tuija; Tuovinen, Timo; Isokangas, Matti; Sonkajärvi, Eila; Siniluoto, Topi; Nikkinen, Juha; Alahuhta, Seppo; Tervonen, Osmo; Turpeenniemi-Hujanen, Taina; Myllylä, Teemu; Kuittinen, Outi; Voipio, Juha

2017-01-01

Chemotherapy aided by opening of the blood-brain barrier with intra-arterial infusion of hyperosmolar mannitol improves the outcome in primary central nervous system lymphoma. Proper opening of the blood-brain barrier is crucial for the treatment, yet there are no means available for its real-time monitoring. The intact blood-brain barrier maintains a mV-level electrical potential difference between blood and brain tissue, giving rise to a measurable electrical signal at the scalp. Therefore, we used direct-current electroencephalography (DC-EEG) to characterize the spatiotemporal behavior of scalp-recorded slow electrical signals during blood-brain barrier opening. Nine anesthetized patients receiving chemotherapy were monitored continuously during 47 blood-brain barrier openings induced by carotid or vertebral artery mannitol infusion. Left or right carotid artery mannitol infusion generated a strongly lateralized DC-EEG response that began with a 2 min negative shift of up to 2000 μV followed by a positive shift lasting up to 20 min above the infused carotid artery territory, whereas contralateral responses were of opposite polarity. Vertebral artery mannitol infusion gave rise to a minimally lateralized and more uniformly distributed slow negative response with a posterior-frontal gradient. Simultaneously performed near-infrared spectroscopy detected a multiphasic response beginning with mannitol-bolus induced dilution of blood and ending in a prolonged increase in the oxy/deoxyhemoglobin ratio. The pronounced DC-EEG shifts are readily accounted for by opening and sealing of the blood-brain barrier. These data show that DC-EEG is a promising real-time monitoring tool for blood-brain barrier disruption augmented drug delivery. PMID:28319185

[The blood-brain barrier and drug delivery in the central nervous system].

PubMed

Loch-Neckel, Gecioni; Koepp, Janice

2010-08-01

To provide an updated view of the difficulties due to barriers and strategies used to allow the release of drugs in the central nervous system. The difficulty for the treatment of many diseases of the central nervous system, through the use of intra-venous drugs, is due to the presence of barriers that prevent the release of the same: the blood-brain barrier, blood-cerebro-spinal fluid barrier and the blood-arachnoid barrier. The blood-brain barrier is the main barrier for the transport of drugs in the brain that also acts as a immunologic and metabolic barrier. The endothelial cells of the blood-brain barrier are connected to a junction complex through the interaction of transmembrane proteins that protrude from de inside to the outside, forming a connection between the endothelial cells. The transport of substances to the brain depends on the mechanisms of transport present in the barrier and the diffusion of these compounds also depends on the physicochemical characteristics of the molecule. Some diseases alter the permeability of the blood-brain barrier and thus the passage of drugs. Strategies such as the use of methods for drug delivery in the brain have been investigated. Further details regarding the mechanisms of transport across the blood-brain barrier and the changes in neuropathology would provide important information about the etiology of diseases and lead to better therapeutic strategies.

Getting the right blood to the right patient: the contribution of near-miss event reporting and barrier analysis.

PubMed

Kaplan, H S

2005-11-01

Safety and reliability in blood transfusion are not static, but are dynamic non-events. Since performance deviations continually occur in complex systems, their detection and correction must be accomplished over and over again. Non-conformance must be detected early enough to allow for recovery or mitigation. Near-miss events afford early detection of possible system weaknesses and provide an early chance at correction. National event reporting systems, both voluntary and involuntary, have begun to include near-miss reporting in their classification schemes, raising awareness for their detection. MERS-TM is a voluntary safety reporting initiative in transfusion. Currently 22 hospitals submit reports anonymously to a central database which supports analysis of a hospital's own data and that of an aggregate database. The system encourages reporting of near-miss events, where the patient is protected from receiving an unsuitable or incorrect blood component due to a planned or unplanned recovery step. MERS-TM data suggest approximately 90% of events are near-misses, with 10% caught after issue but before transfusion. Near-miss reporting may increase total reports ten-fold. The ratio of near-misses to events with harm is 339:1, consistent with other industries' ratio of 300:1, which has been proposed as a measure of reporting in event reporting systems. Use of a risk matrix and an event's relation to protective barriers allow prioritization of these events. Near-misses recovered by planned barriers occur ten times more frequently then unplanned recoveries. A bedside check of the patient's identity with that on the blood component is an essential, final barrier. How the typical two person check is performed, is critical. Even properly done, this check is ineffective against sampling and testing errors. Blood testing at bedside just prior to transfusion minimizes the risk of such upstream events. However, even with simple and well designed devices, training may be a critical issue. Sample errors account for more than half of reported events. The most dangerous miscollection is a blood sample passing acceptance with no previous patient results for comparison. Bar code labels or collection of a second sample may counter this upstream vulnerability. Further upstream barriers have been proposed to counter the precariousness of urgent blood sample collection in a changing unstable situation. One, a linking device, allows safer labeling of tubes away from the bedside, the second, a forcing function, prevents omission of critical patient identification steps. Errors in the blood bank itself account for 15% of errors with a high potential severity. In one such event, a component incorrectly issued, but safely detected prior to transfusion, focused attention on multitasking's contribution to laboratory error. In sum, use of near-miss information, by enhancing barriers supporting error prevention and mitigation, increases our capacity to get the right blood to the right patient.

Blood-brain barrier-on-a-chip: Microphysiological systems that capture the complexity of the blood-central nervous system interface.

PubMed

Phan, Duc Tt; Bender, R Hugh F; Andrejecsk, Jillian W; Sobrino, Agua; Hachey, Stephanie J; George, Steven C; Hughes, Christopher Cw

2017-11-01

The blood-brain barrier is a dynamic and highly organized structure that strictly regulates the molecules allowed to cross the brain vasculature into the central nervous system. The blood-brain barrier pathology has been associated with a number of central nervous system diseases, including vascular malformations, stroke/vascular dementia, Alzheimer's disease, multiple sclerosis, and various neurological tumors including glioblastoma multiforme. There is a compelling need for representative models of this critical interface. Current research relies heavily on animal models (mostly mice) or on two-dimensional (2D) in vitro models, neither of which fully capture the complexities of the human blood-brain barrier. Physiological differences between humans and mice make translation to the clinic problematic, while monolayer cultures cannot capture the inherently three-dimensional (3D) nature of the blood-brain barrier, which includes close association of the abluminal side of the endothelium with astrocyte foot-processes and pericytes. Here we discuss the central nervous system diseases associated with blood-brain barrier pathology, recent advances in the development of novel 3D blood-brain barrier -on-a-chip systems that better mimic the physiological complexity and structure of human blood-brain barrier, and provide an outlook on how these blood-brain barrier-on-a-chip systems can be used for central nervous system disease modeling. Impact statement The field of microphysiological systems is rapidly evolving as new technologies are introduced and our understanding of organ physiology develops. In this review, we focus on Blood-Brain Barrier (BBB) models, with a particular emphasis on how they relate to neurological disorders such as Alzheimer's disease, multiple sclerosis, stroke, cancer, and vascular malformations. We emphasize the importance of capturing the three-dimensional nature of the brain and the unique architecture of the BBB - something that until recently had not been well modeled by in vitro systems. Our hope is that this review will provide a launch pad for new ideas and methodologies that can provide us with truly physiological BBB models capable of yielding new insights into the function of this critical interface.

Human gene therapy: novel approaches to improve the current gene delivery systems.

PubMed

Cucchiarini, Magali

2016-06-01

Even though gene therapy made its way through the clinics to treat a number of human pathologies since the early years of experimental research and despite the recent approval of the first gene-based product (Glybera) in Europe, the safe and effective use of gene transfer vectors remains a challenge in human gene therapy due to the existence of barriers in the host organism. While work is under active investigation to improve the gene transfer systems themselves, the use of controlled release approaches may offer alternative, convenient tools of vector delivery to achieve a performant gene transfer in vivo while overcoming the various physiological barriers that preclude its wide use in patients. This article provides an overview of the most significant contributions showing how the principles of controlled release strategies may be adapted for human gene therapy.

Abusive behavior is barrier to high-reliability health care systems, culture of patient safety.

PubMed

Cassirer, C; Anderson, D; Hanson, S; Fraser, H

2000-11-01

Addressing abusive behavior in the medical workplace presents an important opportunity to deliver on the national commitment to improve patient safety. Fundamentally, the issue of patient safety and the issue of abusive behavior in the workplace are both about harm. Undiagnosed and untreated, abusive behavior is a barrier to creating high reliability service delivery systems that ensure patient safety. Health care managers and clinicians need to improve their awareness, knowledge, and understanding of the issue of workplace abuse. The available research suggests there is a high prevalence of workplace abuse in medicine. Both administrators at the blunt end and clinicians at the sharp end should consider learning new approaches to defining and treating the problem of workplace abuse. Eliminating abusive behavior has positive implications for preventing and controlling medical injury and improving organizational performance.

Burner Rig Evaluation of Thermal Barrier Coating Systems for Nickel-Base Alloys

NASA Technical Reports Server (NTRS)

Gedwill, M. A.

1981-01-01

Eight plasma sprayed bond coatings were evaluated for their potential use with ZrO2-Y2O3 thermal barrier coatings (TECs) which are being developed for coal derived fuel fired gas turbines. Longer TBC lives in cyclic burner rig oxidation to 1050 C were achieved with the more oxidation resistant bond coatings. These were Ni-14.1Cr-13.4A1-0.10Ar, Ni-14.1C4-14.4Al-0.16Y, and Ni-15.8Cr-12.8Al-0.36Y on Rene 41. The TBC systems performed best when 0.015-cm thick bond coatings were employed that were sprayed at 20 kW using argon 3.5v/o hydrogen. Cycling had a more life limiting influence on the TBC than accumulated time at 1050 C.

Results of a feasibility study: barriers and facilitators in implementing the Sherbrooke model in France.

PubMed

Fassier, Jean-Baptiste; Durand, Marie-José; Caillard, Jean-François; Roquelaure, Yves; Loisel, Patrick

2015-05-01

Return-to-work interventions associated with the workplace environment are often more effective than conventional care. The Sherbrooke model is an integrated intervention that has proved successful in preventing work disability due to low-back pain. Implementation, however, runs up against many obstacles, and failure has been reported in many countries. The present study sought to identify barriers to and facilitators of the implementation of the Sherbrooke model within the French health system. A multiple case study with nested levels of analysis was performed in two regions of France. A conceptual framework was designed and refined to identify barriers and facilitators at the individual, organizational and contextual levels. Qualitative data were collected via semi-structured interview (N=22), focus groups (N=7), and observation and from the gray literature. Participants (N=61) belonged to three fields: healthcare, social insurance, and the workplace. Numerous barriers and facilitators were identified in each field and at each level, some specific and others common to workers in all fields. Individual and organizational barriers comprised lack of time and resources, discordant professional values, and perceived risk. Legal barriers comprised medical confidentiality, legal complexity, and priority given to primary prevention. Individual-level facilitators comprised needs and perceived benefits. Some organizations had concordant values and practices. Legal facilitators comprised possibilities of collaboration and gradual return to work. The present feasibility analysis of implementing the Sherbrooke model revealed numerous barriers and facilitators suggesting a new implementation strategy be drawn up if failure is to be avoided.

Method of sealing casings of subsurface materials management system

DOEpatents

Nickelson, Reva A.; Richardson, John G.; Kostelnik, Kevin M.; Sloan, Paul A.

2007-02-06

Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

Sub-barrier fusion of Si+Si systems

NASA Astrophysics Data System (ADS)

Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Bourgin, D.; Čolović, P.; Corradi, L.; Courtin, S.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Urbani, M.; Szilner, S.; Zhang, G. L.

2017-11-01

The near- and sub-barrier fusion excitation function has been measured for the system 30Si+30Si at the Laboratori Nazionali di Legnaro of INFN, using the 30Si beam of the XTU Tandem accelerator in the energy range 47 - 90 MeV. A set-up based on a beam electrostatic deflector was used for detecting fusion evaporation residues. The measured cross sections have been compared to previous data on 28Si+28Si and Coupled Channels (CC) calculations have been performed using M3Y+repulsion and Woods-Saxon potentials, where the lowlying 2+ and 3- excitations have been included. A weak imaginary potential was found to be necessary to reproduce the low energy 28Si+28Si data. This probably simulates the effect of the oblate deformation of this nucleus. On the contrary, 30Si is a spherical nucleus, 30Si+30Si is nicely fit by CC calculations and no imaginary potential is needed. For this system, no maximum shows up for the astrophysical S-factor so that we have no evidence for hindrance, as confirmed by the comparison with CC calculations. The logarithmic derivative of the two symmetric systems highlights their different low energy trend. A difference can also be noted in the two barrier distributions, where the high-energy peak present in 28Si+28Si is not observed for 30Si+30Si, probably due to the weaker couplings in last case.

Benefits, barriers, and limitations on the use of Hospital Incident Command System.

PubMed

Shooshtari, Shahin; Tofighi, Shahram; Abbasi, Shirin

2017-01-01

Hospital Incident Command System (HICS) has been established with the mission of prevention, response, and recovery in hazards. Regarding the key role of hospitals in medical management of events, the present study is aimed at investigating benefits, barriers, and limitations of applying HICS in hospital. Employing a review study, articles related to the aforementioned subject published from 1995 to 2016 were extracted from accredited websites and databases such as PubMed, Google Scholar, Elsevier, and SID by searching keywords such as HICS, benefits, barriers, and limitations. Then, those articles were summarized and reported. Using of HICS can cause creating preparedness in facing disasters, constructive management in strategies of controlling events, and disasters. Therefore, experiences indicate that there are some limitations in the system such as failure to assess the strength and severity of vulnerabilities of hospital, no observation of standards for disaster management in the design, constructing and equipping hospitals, and the absence of a model for evaluating the system. Accordingly, the conducted studies were investigated for probing the performance HICS. With regard to the role of health in disaster management, it requires advanced international methods in facing disasters. Using accurate models for assessing, the investigation of preparedness of hospitals in precrisis conditions based on components such as command, communications, security, safety, development of action plans, changes in staff's attitudes through effective operational training and exercises and creation of required maneuvers seems necessary.

Limitations of and Barriers to Using Performance Measurement: Purchasers' Perspectives

PubMed Central

Ginsberg, Caren; Sheridan, Samantha

2001-01-01

Although health plan performance data are becoming increasingly more available, many purchasers are still not using these data to make their purchasing decisions. In this article, we review barriers that private purchasers face to using performance data. In addition, we consider the effects of the larger health care purchasing environment and employers' quality improvement activities on their use of the data. We conclude that a variety of factors, including trends, the health care purchasing environment, characteristics of firms, and problems with performance data and their presentation to users create barriers to incorporating this information into health care decisionmaking. PMID:25372184

Effect Of N = 40 Shell Closure On Barrier Distributions In 18O+58,60Ni Reactions

NASA Astrophysics Data System (ADS)

Danu, L. S.; Nayak, B. K.; Saxena, A.; Biswas, D. C.; John, B. V.; Thomas, R. G.; Gupta, Y. K.; Choudhury, R. K.

2009-03-01

The quasi-elastic scattering measurements for 18O+58,62Ni systems have been carried out at Θlab = 150° around Coulomb barrier energies to investigate the effect of nuclear shell closure on the barrier distributions. The 18O+58Ni system leads to N = 40 neutron shell closure and 18O+62Ni system is having N = 44 in the compound system. It is observed that target 2+ and 3-, projectile 2+ inelastic and 2n-transfer couplings are required in coupled-channels fusion model (CCFULL) calculations to get good comparison with the experimental barrier distribution of 18O+62Ni system, whereas projectile 2+ inelastic state coupling is not required for 18O+58Ni system. However, the low energy structure observed in the barrier distribution of 18O+58Ni system is not reproduced by coupled-channels calculations. This suggests, a possible additional effect due to N = 40 shell closure in the compound system not accounted for in coupled-channels calculations.

Performance Assessment of a Permeable Reactive Barrier for Ground Water Remediation Fifteen Years After Installation

EPA Science Inventory

The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminanttreatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium sourc...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, A.; Hsiung, S.M.; Chowdhury, A.H.

Long-term stability of emplacement drifts and potential near-field fluid flow resulting from coupled effects are among the concerns for safe disposal of high-level nuclear waste (HLW). A number of factors can induce drift instability or change the near-field flow patterns. Repetitive seismic loads from earthquakes and thermal loads generated by the decay of emplaced waste are two significant factors. One of two key technical uncertainties (KTU) that can potentially pose a high risk of noncompliance with the performance objectives of 10 CFR Part 60 is the prediction of thermal-mechanical (including repetitive seismic load) effects on stability of emplacement drifts andmore » the engineered barrier system. The second KTU of concern is the prediction of thermal-mechanical-hydrological (including repetitive seismic load) effects on the host rock surrounding the engineered barrier system. The Rock Mechanics research project being conducted at the Center for Nuclear Waste Regulatory Analyses (CNWRA) is intended to address certain specific technical issues associated with these two KTUs. This research project has two major components: (i) seismic response of rock joints and a jointed rock mass and (ii) coupled thermal-mechanical-hydrological (TMH) response of a jointed rock mass surrounding the engineered barrier system (EBS). This final report summarizes the research activities concerned with the repetitive seismic load aspect of both these KTUs.« less

Current Limitations of Surgical Robotics in Reconstructive Plastic Microsurgery.

PubMed

Tan, Youri P A; Liverneaux, Philippe; Wong, Jason K F

2018-01-01

Surgical robots have the potential to provide surgeons with increased capabilities, such as removing physiologic tremor, scaling motion and increasing manual dexterity. Several surgical specialties have subsequently integrated robotic surgery into common clinical practice. Plastic and reconstructive microsurgical procedures have not yet  benefitted significantly from technical developments observed over the last two decades. Several studies have successfully demonstrated the feasibility of utilising surgical robots in plastic surgery procedures, yet limited work has been done to identify and analyse current barriers that have prevented wide-scale adaptation of surgical robots for microsurgery. Therefore, a systematic review using PubMed, MEDLINE, Embase and Web of Science databases was performed, in order to evaluate current state of surgical robotics within the field of reconstructive microsurgery and their limitations. Despite the theoretical potential of surgical robots, current commercially available robotic systems are suboptimal for plastic or reconstructive microsurgery. Absence of bespoke microsurgical instruments, increases in operating time, and high costs associated with robotic-assisted provide a barrier to using such systems effectively for reconstructive microsurgery. Consequently, surgical robots provide currently little overall advantage over conventional microsurgery. Nevertheless, if current barriers can be addressed and systems are specifically designed for microsurgery, surgical robots may have the potential of meaningful impact on clinical outcomes within  this surgical subspeciality.

Current Limitations of Surgical Robotics in Reconstructive Plastic Microsurgery

PubMed Central

Tan, Youri P. A.; Liverneaux, Philippe; Wong, Jason K. F.

2018-01-01

Surgical robots have the potential to provide surgeons with increased capabilities, such as removing physiologic tremor, scaling motion and increasing manual dexterity. Several surgical specialties have subsequently integrated robotic surgery into common clinical practice. Plastic and reconstructive microsurgical procedures have not yet  benefitted significantly from technical developments observed over the last two decades. Several studies have successfully demonstrated the feasibility of utilising surgical robots in plastic surgery procedures, yet limited work has been done to identify and analyse current barriers that have prevented wide-scale adaptation of surgical robots for microsurgery. Therefore, a systematic review using PubMed, MEDLINE, Embase and Web of Science databases was performed, in order to evaluate current state of surgical robotics within the field of reconstructive microsurgery and their limitations. Despite the theoretical potential of surgical robots, current commercially available robotic systems are suboptimal for plastic or reconstructive microsurgery. Absence of bespoke microsurgical instruments, increases in operating time, and high costs associated with robotic-assisted provide a barrier to using such systems effectively for reconstructive microsurgery. Consequently, surgical robots provide currently little overall advantage over conventional microsurgery. Nevertheless, if current barriers can be addressed and systems are specifically designed for microsurgery, surgical robots may have the potential of meaningful impact on clinical outcomes within  this surgical subspeciality. PMID:29740585

Barriers and facilitators to recovering from e-prescribing errors in community pharmacies.

PubMed

Odukoya, Olufunmilola K; Stone, Jamie A; Chui, Michelle A

2015-01-01

To explore barriers and facilitators to recovery from e-prescribing errors in community pharmacies and to explore practical solutions for work system redesign to ensure successful recovery from errors. Cross-sectional qualitative design using direct observations, interviews, and focus groups. Five community pharmacies in Wisconsin. 13 pharmacists and 14 pharmacy technicians. Observational field notes and transcribed interviews and focus groups were subjected to thematic analysis guided by the Systems Engineering Initiative for Patient Safety (SEIPS) work system and patient safety model. Barriers and facilitators to recovering from e-prescription errors in community pharmacies. Organizational factors, such as communication, training, teamwork, and staffing levels, play an important role in recovering from e-prescription errors. Other factors that could positively or negatively affect recovery of e-prescription errors include level of experience, knowledge of the pharmacy personnel, availability or usability of tools and technology, interruptions and time pressure when performing tasks, and noise in the physical environment. The SEIPS model sheds light on key factors that may influence recovery from e-prescribing errors in pharmacies, including the environment, teamwork, communication, technology, tasks, and other organizational variables. To be successful in recovering from e-prescribing errors, pharmacies must provide the appropriate working conditions that support recovery from errors.

Pentacle gold-copper alloy nanocrystals: a new system for entering male germ cells in vitro and in vivo

NASA Astrophysics Data System (ADS)

Lin, Yu; He, Rong; Sun, Liping; Yang, Yushan; Li, Wenqing; Sun, Fei

2016-12-01

Gold-based nanocrystals have attracted considerable attention for drug delivery and biological applications due to their distinct shapes. However, overcoming biological barriers is a hard and inevitable problem, which restricts medical applications of nanomaterials in vivo. Seeking for an efficient transportation to penetrate biological barriers is a common need. There are three barriers: blood-testis barrier, blood-placenta barrier, and blood-brain barrier. Here, we pay close attention to the blood-testis barrier. We found that the pentacle gold-copper alloy nanocrystals not only could enter GC-2 cells in vitro in a short time, but also could overcome the blood-testis barrier and enter male germ cells in vivo. Furthermore, we demonstrated that the entrance efficiency would become much higher in the development stages. The results also suggested that the pentacle gold-copper alloy nanocrystals could easier enter to germ cells in the pathological condition. This system could be a new method for theranostics in the reproductive system.

Development of biodegradable materials; balancing degradability and performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayer, J.M.; Allen, A.L.; Dell, P.A.

1993-12-31

The development of biodegradable materials suitable for packaging must take into consideration various performance criteria such as mechanical and barrier properties, as well as rate of biodegradability in given environments. Individual or blended biopolymer films were obtained commercially or blown into film in the laboratory and tested for tensile strength, ultimate elongation and oxygen barrier. These films were then subjected to accelerated marine biodegradation tests as well as simulated marine respirometry. Starch/ethylene vinyl alcohol films exhibited good mechanical and excellent oxygen barrier properties, but were very slow to biodegrade in the simulated and excellent oxygen barrier properties, but were verymore » slow to biodegrade in the simulated marine environment. Polyhydroxyalkanoates had good mechanical properties, average oxygen barrier and good biodegradability. Data indicate that performance and biodegradability of packaging can be tailored to needs by combining individual biopolymers in different proportions in blends and laminates.« less

Systematic Benchmarking of Diagnostic Technologies for an Electrical Power System

NASA Technical Reports Server (NTRS)

Kurtoglu, Tolga; Jensen, David; Poll, Scott

2009-01-01

Automated health management is a critical functionality for complex aerospace systems. A wide variety of diagnostic algorithms have been developed to address this technical challenge. Unfortunately, the lack of support to perform large-scale V&V (verification and validation) of diagnostic technologies continues to create barriers to effective development and deployment of such algorithms for aerospace vehicles. In this paper, we describe a formal framework developed for benchmarking of diagnostic technologies. The diagnosed system is the Advanced Diagnostics and Prognostics Testbed (ADAPT), a real-world electrical power system (EPS), developed and maintained at the NASA Ames Research Center. The benchmarking approach provides a systematic, empirical basis to the testing of diagnostic software and is used to provide performance assessment for different diagnostic algorithms.

Design and validation of a microfluidic device for blood-brain barrier monitoring and transport studies

NASA Astrophysics Data System (ADS)

Ugolini, Giovanni Stefano; Occhetta, Paola; Saccani, Alessandra; Re, Francesca; Krol, Silke; Rasponi, Marco; Redaelli, Alberto

2018-04-01

In vitro blood-brain barrier models are highly relevant for drug screening and drug development studies, due to the challenging task of understanding the transport mechanism of drug molecules through the blood-brain barrier towards the brain tissue. In this respect, microfluidics holds potential for providing microsystems that require low amounts of cells and reagent and can be potentially multiplexed for increasing the ease and throughput of the drug screening process. We here describe the design, development and validation of a microfluidic device for endothelial blood-brain barrier cell transport studies. The device comprises of two microstructured layers (top culture chamber and bottom collection chamber) sandwiching a porous membrane for the cell culture. Microstructured layers include two pairs of physical electrodes, embedded into the device layers by geometrically defined guiding channels with computationally optimized positions. These electrodes allow the use of commercial electrical measurement systems for monitoring trans-endothelial electrical resistance (TEER). We employed the designed device for performing preliminary assessment of endothelial barrier formation with murine brain endothelial cells (Br-bEnd5). Results demonstrate that cellular junctional complexes effectively form in the cultures (expression of VE-Cadherin and ZO-1) and that the TEER monitoring systems effectively detects an increase of resistance of the cultured cell layers indicative of tight junction formation. Finally, we validate the use of the described microsystem for drug transport studies demonstrating that Br-bEnd5 cells significantly hinder the transport of molecules (40 kDa and 4 kDa dextran) from the top culture chamber to the bottom collection chamber.

Acceptance and barriers pertaining to a general practice decision support system for multiple clinical conditions: A mixed methods evaluation.

PubMed

Arts, Derk L; Medlock, Stephanie K; van Weert, Henk C P M; Wyatt, Jeremy C; Abu-Hanna, Ameen

2018-01-01

Many studies have investigated the use of clinical decision support systems as a means to improve care, but have thus far failed to show significant effects on patient-related outcomes. We developed a clinical decision support system that attempted to address issues that were identified in these studies. The system was implemented in Dutch general practice and was designed to be both unobtrusive and to respond in real time. Despite our efforts, usage of the system was low. In the current study we perform a mixed methods evaluation to identify remediable barriers which led to disappointing usage rates for our system. A mixed methods evaluation employing an online questionnaire and focus group. The focus group was organized to clarify free text comments and receive more detailed feedback from general practitioners. Topics consisted of items based on results from the survey and additional open questions. The response rate for the questionnaire was 94%. Results from the questionnaire and focus group can be summarized as follows: The system was perceived as interruptive, despite its design. Participants felt that there were too many recommendations and that the relevance of the recommendations varied. Demographic based recommendations (e.g. age) were often irrelevant, while specific risk-based recommendations (e.g. diagnosis) were more relevant. The other main barrier to use was lack of time during the patient visit. These results are likely to be useful to other researchers who are attempting to address the problems of interruption and alert fatigue in decision support.

Metallic seal for thermal barrier coating systems

NASA Technical Reports Server (NTRS)

Miller, Robert A. (Inventor)

1990-01-01

The invention is particularly concerned with sealing thermal barrier coating systems of the type in use and being contemplated for use in diesel and other internal combustion engines. The invention also would find application in moderately high temperature regions of gas turbine engines and any other application employing a thermal barrier coating at moderate temperatures. Ni-35Cr-6Al-1Y, Ni-35Cr-6Al-1Yb, or other metallic alloy denoted as MCrAlx is applied over a zirconia-based thermal barrier overlayer. The close-out layer is glass-bead preened to densify its surface. This seals and protects the thermal barrier coating system.

Feasibility of and barriers to continuity of care in US general surgery residencies with an 80-hour duty week.

PubMed

Morrissey, Shawna; Dumire, Russell; Bost, James; Gregory, James S

2011-03-01

The current level of continuity of care for following up a single patient through preoperative evaluation, surgery, and postoperative care is unknown. A survey of residents was performed, asking for their best guess regarding the number of patients seen for 6 common and 4 uncommon surgeries, and ranking barriers to continuity of care. The length of time to achieve single-patient continuity of care in 5 patients was derived as well as the creation of odds ratios for the barriers. A total of 274 residents (56 programs) completed surveys. Residency length was 7 years for common surgeries and 9 for complex surgeries. The 30-hour work restrictions, inability to attend clinic, and floor/ward duties were the barriers to continuity of care. These data were unaffected by type of program, the presence of a night float system, or residency year. Achieving the level of continuity of care used in this article will require a radical change in the length or structure of general surgery residency programs. Copyright © 2011 Elsevier Inc. All rights reserved.

Micro pore arrays in free standing cyclic olefin copolymer membranes: fabrication and surface functionalization strategies for in-vitro barrier tissue models

NASA Astrophysics Data System (ADS)

Gel, M.; Kandasamy, S.; Cartledge, K.; Be, C. L.; Haylock, D.

2013-12-01

In recent years there has been growing interest in micro engineered in-vitro models of tissues and organs. These models are designed to mimic the in-vivo like physiological conditions with a goal to study human physiology in an organ-specific context or to develop in-vitro disease models. One of the challenges in the development of these models is the formation of barrier tissues in which the permeability is controlled locally by the tissues cultured at the interface. In-vitro models of barrier tissues are typically created by generating a monolayer of cells grown on thin porous membranes. This paper reports a robust preparation method for free standing porous cyclic olefin copolymer (COC) membranes. We also demonstrate that gelatin coated membranes facilitate formation of highly confluent monolayer of HUVECs. Membranes with thickness in the range of 2-3 um incorporating micro pores with diameter approximately 20 um were fabricated and integrated with microfluidic channels. The performance of the device was demonstrated with a model system mimicking the endothelial barrier in bone marrow sinusoids.

Barriers and motivators to blood and cord blood donations in young African-American women.

PubMed

Grossman, Brenda; Watkins, Andre R; Fleming, Faye; Debaun, Michael R

2005-03-01

The primary aim of this study was to assess potential barriers and motivators to blood and cord blood donation among African-American women. A telephone survey of African-American women, ages 18-30 years, in the St. Louis metropolitan area was performed. The survey was administered by trained telemarketing personnel using a Computer-Assisted Direct Interview (CADI) system. One hundred sixty-two women were surveyed. Common barriers to blood donation were inconvenience of donor sites (19%), fear of needles (16%), and too much time required to donate (15%). Potential motivators were increasing awareness of need for blood (43%), increasing the number of convenient donor locations (19%), and encouragement by spiritual leaders to have blood drives at their church (17%). Lack of awareness was the only identified barrier to cord blood donation. Most women surveyed (88%) indicated that they definitely or probably would donate cord blood. Strategies to increase the proportion of African-American blood and cord blood donations may include educating potential donors about the process and benefits of donation to particular patient populations and engaging church leadership in supporting blood and cord blood donations.

A Computational Methodology to Screen Activities of Enzyme Variants

PubMed Central

Hediger, Martin R.; De Vico, Luca; Svendsen, Allan; Besenmatter, Werner; Jensen, Jan H.

2012-01-01

We present a fast computational method to efficiently screen enzyme activity. In the presented method, the effect of mutations on the barrier height of an enzyme-catalysed reaction can be computed within 24 hours on roughly 10 processors. The methodology is based on the PM6 and MOZYME methods as implemented in MOPAC2009, and is tested on the first step of the amide hydrolysis reaction catalyzed by the Candida Antarctica lipase B (CalB) enzyme. The barrier heights are estimated using adiabatic mapping and shown to give barrier heights to within 3 kcal/mol of B3LYP/6-31G(d)//RHF/3-21G results for a small model system. Relatively strict convergence criteria (0.5 kcal/(molÅ)), long NDDO cutoff distances within the MOZYME method (15 Å) and single point evaluations using conventional PM6 are needed for reliable results. The generation of mutant structures and subsequent setup of the semiempirical calculations are automated so that the effect on barrier heights can be estimated for hundreds of mutants in a matter of weeks using high performance computing. PMID:23284627

A virtual-system coupled multicanonical molecular dynamics simulation: Principles and applications to free-energy landscape of protein-protein interaction with an all-atom model in explicit solvent

NASA Astrophysics Data System (ADS)

Higo, Junichi; Umezawa, Koji; Nakamura, Haruki

2013-05-01

We propose a novel generalized ensemble method, a virtual-system coupled multicanonical molecular dynamics (V-McMD), to enhance conformational sampling of biomolecules expressed by an all-atom model in an explicit solvent. In this method, a virtual system, of which physical quantities can be set arbitrarily, is coupled with the biomolecular system, which is the target to be studied. This method was applied to a system of an Endothelin-1 derivative, KR-CSH-ET1, known to form an antisymmetric homodimer at room temperature. V-McMD was performed starting from a configuration in which two KR-CSH-ET1 molecules were mutually distant in an explicit solvent. The lowest free-energy state (the most thermally stable state) at room temperature coincides with the experimentally determined native complex structure. This state was separated to other non-native minor clusters by a free-energy barrier, although the barrier disappeared with elevated temperature. V-McMD produced a canonical ensemble faster than a conventional McMD method.

Energy analysis of vehicle-to-cable barrier impacts.

DOT National Transportation Integrated Search

2013-06-01

An accident reconstruction technique was developed for estimating the energy absorbed during an impact with a cable barrier system as well as the initial impact velocity. The kinetic energy absorbed during a cable barrier system impact is comprised o...

Energy efficient engine, high pressure turbine thermal barrier coating. Support technology report

NASA Technical Reports Server (NTRS)

Duderstadt, E. C.; Agarwal, P.

1983-01-01

This report describes the work performed on a thermal barrier coating support technology task of the Energy Efficient Engine Component Development Program. A thermal barrier coating (TBC) system consisting of a Ni-Cr-Al-Y bond cost layer and ZrO2-Y2O3 ceramic layer was selected from eight candidate coating systems on the basis of laboratory tests. The selection was based on coating microstructure, crystallographic phase composition, tensile bond and bend test results, erosion and impact test results, furnace exposure, thermal cycle, and high velocity dynamic oxidation test results. Procedures were developed for applying the selected TBC to CF6-50, high pressure turbine blades and vanes. Coated HPT components were tested in three kinds of tests. Stage 1 blades were tested in a cascade cyclic test rig, Stage 2 blades were component high cycle fatigue tested to qualify thermal barrier coated blades for engine testing, and Stage 2 blades and Stage 1 and 2 vanes were run in factory engine tests. After completion of the 1000 cycle engine test, the TBC on the blades was in excellent condition over all of the platform and airfoil except at the leading edge above midspan on the suction side of the airfoil. The coating damage appeared to be caused by particle impingement; adjacent blades without TBC also showed evidence of particle impingement.

Low temperature barriers with heat interceptor wells for in situ processes

DOEpatents

McKinzie, II, Billy John

2008-10-14

A system for reducing heat load applied to a frozen barrier by a heated formation is described. The system includes heat interceptor wells positioned between the heated formation and the frozen barrier. Fluid is positioned in the heat interceptor wells. Heat transfers from the formation to the fluid to reduce the heat load applied to the frozen barrier.

A design perspective on thermal barrier coatings

NASA Astrophysics Data System (ADS)

Soechting, F. O.

1999-12-01

This article addresses the challenges for maximizing the benefit of thermal barrier coatings for turbine engine applications. The perspective is from the viewpoint of a customer, a turbine airfoil designer who is continuously challenged to increase the turbine inlet temperature capability for new products while maintaining cooling flow levels or even reducing them. This is a fundamental requirement for achieving increased engine thrust levels. Developing advanced material systems for the turbine flowpath airfoils, such as high-temperature nickel-base superalloys or thermal barrier coatings to insulate the metal airfoils from the hot flowpath environment, is one approach to solve this challenge. The second approach is to increase the cooling performance of the turbine airfoil, which enables increased flowpath temperatures and reduced cooling flow levels. Thermal barrier coatings have been employed in jet engine applications for almost 30 years. The initial application was on augmentor liners to provide thermal protection during afterburner operation. However, the production use of thermal barrier coatings in the turbine section has only occurred in the past 15 years. The application was limited to stationary parts and only recently incorporated on the rotating turbine blades. This lack of endorsement of thermal barrier coatings resulted from the poor initial duratbility of these coatings in high heat flux environments. Significant improvements have been made to enhance spallation resistance and erosion resistance, which has resulted in increased reliability of these coatings in turbine applications.

Substitution of Hospital Care with Primary Care: Defining the Conditions of Primary Care Plus

PubMed Central

Kroese, Mariëlle Elisabeth Aafje Lydia; Spreeuwenberg, Marieke Dingena; Elissen, Arianne Mathilda Josephus; Meerlo, Ronald Johan; Hanraets, Monique Margaretha Henriëtte; Ruwaard, Dirk

2016-01-01

Objective: To analyse barriers and facilitators in substituting hospital care with primary care to define preconditions for successful implementation. Methods: A descriptive feasibility study was performed to collect information on the feasibility of substituting hospital care with primary care. General practitioners were able to refer patients, about whom they had doubts regarding diagnosis, treatment and/or the need to refer to hospital care, to medical specialists who performed low-complex consultations at general practitioner practices. Qualitative data were collected through interviews with general practitioners and medical specialists, focus groups and notes from meetings in the Netherlands between April 2013 and January 2014. Data were analysed using a conventional content analysis which resulted in categorised barriers, facilitators and policy adjustments, after which preconditions were formulated. Results: The most important preconditions were make arrangements on governmental level, arrange a collective integrated IT-system, determine the appropriate profile for medical specialists, design a referral protocol for eligible patients, arrange deliberation possibilities for general practitioners and medical specialists and formulate a diagnostic protocol. Conclusions: The barriers, facilitators and formulated preconditions provided relevant input to change the design of substituting hospital care with primary care. PMID:27616956

Advances in the Dynallax solid-state dynamic parallax barrier autostereoscopic visualization display system.

PubMed

Peterka, Tom; Kooima, Robert L; Sandin, Daniel J; Johnson, Andrew; Leigh, Jason; DeFanti, Thomas A

2008-01-01

A solid-state dynamic parallax barrier autostereoscopic display mitigates some of the restrictions present in static barrier systems, such as fixed view-distance range, slow response to head movements, and fixed stereo operating mode. By dynamically varying barrier parameters in real time, viewers may move closer to the display and move faster laterally than with a static barrier system, and the display can switch between 3D and 2D modes by disabling the barrier on a per-pixel basis. Moreover, Dynallax can output four independent eye channels when two viewers are present, and both head-tracked viewers receive an independent pair of left-eye and right-eye perspective views based on their position in 3D space. The display device is constructed by using a dual-stacked LCD monitor where a dynamic barrier is rendered on the front display and a modulated virtual environment composed of two or four channels is rendered on the rear display. Dynallax was recently demonstrated in a small-scale head-tracked prototype system. This paper summarizes the concepts presented earlier, extends the discussion of various topics, and presents recent improvements to the system.

Enhancement of the barrier performance in organic/inorganic multilayer thin-film structures by annealing of the parylene layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Namsu, E-mail: nkim@keti.re.kr; Components and Materials Physics Research Center, #68 Yatop-dong, Korea Electronics Technology Institute, Bundang-gu, 463-816; Graham, Samuel

2014-10-15

Highlights: • High performance thin-film barrier structure for encapsulation was fabricated. • By annealing parylene in encapsulation structure, the barrier performance was improved. • The effective water vapor transmission rate is 7.2 ± 3.0 × 10{sup −6} g/m{sup 2}/day. - Abstract: A multilayered barrier structure was fabricated by chemical vapor deposition of parylene and subsequent plasma-enhanced chemical vapor deposition of SiO{sub x} or SiN{sub x}. The barrier performance against water vapor ingress was significantly improved by annealing the parylene layer before the deposition of either SiO{sub x} or SiN{sub x}. The mechanism of this enhancement was investigated using atomic forcemore » microscopy, Raman spectroscopy, and X-ray diffraction. The surface roughness of the parylene before the deposition of either SiO{sub x} or SiN{sub x} was found to correlate closely with the barrier performance of the multilayered structures. In addition, removing absorbed water vapor in the film by annealing results in a lower water vapor transmission rate in the transient region and a longer lag time. Annealing the parylene leads to a large decrease in the effective water vapor transmission rate, which reaches 7.2 ± 3.0 × 10{sup −6} g/m{sup 2}/day.« less

Fusion and direct reactions around the barrier for the systems {sup 7,9}Be,{sup 7}Li+{sup 238}U

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raabe, R.; Angulo, C.; Charvet, J. L.

2006-10-15

We present new cross section data for the complete fusion of the weakly bound systems {sup 7,9}Be and {sup 7}Li on {sup 238}U at energies around the Coulomb barrier. In the same measurement, yields for direct processes and incomplete fusion are detected. For all systems, a suppression of the complete fusion cross section around and above the barrier is observed. At energies below the barrier, the fusion of the {sup 7}Be+{sup 238}U system shows no enhancement with respect to simple model predictions.

Subsurface materials management and containment system, components thereof and methods relating thereto

DOEpatents

Nickelson, Reva A.; Richardson, John G.; Kostelnik, Kevin M.; Sloan, Paul A.

2006-04-18

Systems, components, and methods relating to subterranean containment barriers. Laterally adjacent tubular casings having male interlock structures and multiple female interlock structures defining recesses for receiving a male interlock structure are used to create subterranean barriers for containing and treating buried waste and its effluents. The multiple female interlock structures enable the barriers to be varied around subsurface objects and to form barrier sidewalls. The barrier may be used for treating and monitoring a zone of interest.

EFFECTS OF NUCLEAR INDUCED BREAKUP ON THE FUSION OF 6Li+12C AND 6He+12C SYSTEMS AROUND BARRIER ENERGIES

NASA Astrophysics Data System (ADS)

Duhan, Sukhvinder S.; Singh, Manjeet; Kharab, Rajesh

2012-06-01

We have studied the effects of nuclear induced breakup channel coupling on the fusion cross-section for 6Li+12C and 6He+12C systems in the near barrier energy regime using the dynamic polarization potential (DPP) approach. It has been found that there is enhancement in the fusion cross-section with respect to standard one-dimensional barrier penetration model in the below barrier energy regime while at energies above the barrier there is suppression of fusion cross-section with respect to simple barrier penetration model is observed. The agreement between data and predictions for 6Li+12C system improves significantly as a result of the inclusion of nuclear induced DPP.

The 20 GHz solid state transmitter design, impatt diode development and reliability assessment

NASA Technical Reports Server (NTRS)

Picone, S.; Cho, Y.; Asmus, J. R.

1984-01-01

A single drift gallium arsenide (GaAs) Schottky barrier IMPATT diode and related components were developed. The IMPATT diode reliability was assessed. A proof of concept solid state transmitter design and a technology assessment study were performed. The transmitter design utilizes technology which, upon implementation, will demonstrate readiness for development of a POC model within the 1982 time frame and will provide an information base for flight hardware capable of deployment in a 1985 to 1990 demonstrational 30/20 GHz satellite communication system. Life test data for Schottky barrier GaAs diodes and grown junction GaAs diodes are described. The results demonstrate the viability of GaAs IMPATTs as high performance, reliable RF power sources which, based on the recommendation made herein, will surpass device reliability requirements consistent with a ten year spaceborne solid state power amplifier mission.

An Effective Electrical Resonance-Based Method to Detect Delamination in Thermal Barrier Coating

NASA Astrophysics Data System (ADS)

Kim, Jong Min; Park, Jae-Ha; Lee, Ho Girl; Kim, Hak-Joon; Song, Sung-Jin; Seok, Chang-Sung; Lee, Young-Ze

2017-12-01

This research proposes a simple yet highly sensitive method based on electrical resonance of an eddy-current probe to detect delamination of thermal barrier coating (TBC). This method can directly measure the mechanical characteristics of TBC compared to conventional ultrasonic testing and infrared thermography methods. The electrical resonance-based method can detect the delamination of TBC from the metallic bond coat by shifting the electrical impedance of eddy current testing (ECT) probe coupling with degraded TBC, and, due to this shift, the resonant frequencies near the peak impedance of ECT probe revealed high sensitivity to the delamination. In order to verify the performance of the proposed method, a simple experiment is performed with degraded TBC specimens by thermal cyclic exposure. Consequently, the delamination with growth of thermally grown oxide in a TBC system is experimentally identified. Additionally, the results are in good agreement with the results obtained from ultrasonic C-scanning.

An Effective Electrical Resonance-Based Method to Detect Delamination in Thermal Barrier Coating

NASA Astrophysics Data System (ADS)

Kim, Jong Min; Park, Jae-Ha; Lee, Ho Girl; Kim, Hak-Joon; Song, Sung-Jin; Seok, Chang-Sung; Lee, Young-Ze

2018-02-01

This research proposes a simple yet highly sensitive method based on electrical resonance of an eddy-current probe to detect delamination of thermal barrier coating (TBC). This method can directly measure the mechanical characteristics of TBC compared to conventional ultrasonic testing and infrared thermography methods. The electrical resonance-based method can detect the delamination of TBC from the metallic bond coat by shifting the electrical impedance of eddy current testing (ECT) probe coupling with degraded TBC, and, due to this shift, the resonant frequencies near the peak impedance of ECT probe revealed high sensitivity to the delamination. In order to verify the performance of the proposed method, a simple experiment is performed with degraded TBC specimens by thermal cyclic exposure. Consequently, the delamination with growth of thermally grown oxide in a TBC system is experimentally identified. Additionally, the results are in good agreement with the results obtained from ultrasonic C-scanning.

Efficacy of controlled-release KMnO4 (CRP) for controlling dissolved TCE plume in groundwater: a large flow-tank study.

PubMed

Lee, Byung Sun; Kim, Jeong Hee; Lee, Ki Churl; Kim, Yang Bin; Schwartz, Franklin W; Lee, Eung Seok; Woo, Nam Chil; Lee, Myoung Ki

2009-02-01

A well-based, reactive barrier system using controlled-release potassium permanganate (CRP system) was recently developed as a long-term treatment option for dilute plumes of chlorinated solvents in groundwater. In this study, we performed large-scale (L x W x D = 8 m x 4 m x 2 m) flow-tank experiments to examine remedial efficacy of the CRP system. A total of 110 CRP rods (OD x L=5 cm x 150 cm) were used to construct a well-based CRP system (L x W x D = 3 m x 4 m x 1.5 m) comprising three discrete barriers installed at 1-m interval downstream. Natural sands having oxidant demand of 3.7 g MnO(4)(-)kg(-1) for 500 mg L(-1)MnO(4)(-) were used as porous media. After MnO(4)(-) concentrations were somewhat stabilized (0.5-6.0 mg L(-1)), trichloroethylene (TCE) plume was flowed through the flow-tank for 53 d by supplying 1.19 m(3)d(-1) of TCE solution. Mean initial TCE concentrations were 87 microg L(-1) for first 20 d and 172 microg L(-1) for the next 33 d. During TCE treatment, flow velocity (0.60md(-1)), pH (7.0-8.2), and concentrations of dissolved metals ([Al]=0.7 mg L(-1), [Fe]=0.01 mg L(-1)) showed little variations. The MnO(2)(s) contents in the sandy media measured after the TCE treatment ranged from 21 to 26 mg kg(-1), slightly increased from mean baseline value of 17 mg kg(-1). Strengths of the TCE plume considerably diminished by the CRP system. For the 87 microg L(-1) plume, TCE concentrations decreased by 38% (53), 67% (29), and 74% (23 microg L(-1)) after 1st, 2nd, and 3rd barriers, respectively. For the 172 microg L(-1) plume, TCE concentrations decreased by 27% (125), 46% (93), and 65% (61 microg L(-1)) after 1st, 2nd, and 3rd barriers, respectively. Incomplete destruction of TCE plume was attributed to the lack of lateral dispersion in the unpumped well-based barrier system. Development of delivery systems that can facilitate lateral spreading and mixing of permanganate with contaminant plume is warranted.

Evaluating the long-term hydrology of an evapotranspiration-capillary barrier with a 1000 year design life

NASA Astrophysics Data System (ADS)

Zhang, Z. Fred

2016-06-01

A surface barrier is a commonly used technology for isolation of subsurface contaminants. Surface barriers for isolating radioactive waste are expected to perform for centuries to millennia, yet there are very few data for field-scale surface barriers for periods approaching a decade or longer. The Prototype Hanford Barrier (PHB) with a design life of 1000 years was constructed over an existing radioactive waste site in 1994 to demonstrate its long-term performance. The primary element of the PHB is an evapotranspiration-capillary (ETC) barrier in which precipitation water is stored in a fine-textured soil layer and later released to the atmosphere via evapotranspiration. To address the barrier performance under extreme conditions, this study included an enhanced precipitation stress test from 1995 to 1997 to determine barrier response to extreme precipitation events. During this period a 1000 year 24 h return rainstorm was simulated in March every year. The loss of vegetation on barrier hydrology was tested with a controlled fire test in 2008. The 19 year monitoring record shows that the store-and-release mechanism worked as well as or better than the design criterion. Average drainage from the ETC barrier amounted to an average of 0.005 mm yr-1, which is well below the design criterion of 0.5 mm yr-1. After a simulated wildfire, the naturally reestablished vegetation and increased evaporation combined to release the stored water and summer precipitation to the atmosphere such that drainage did not occur in the 5 years subsequent to the fire.

Noncontacting Laser Inspection System for Dimensional Profiling of Space Application Thermal Barriers

NASA Technical Reports Server (NTRS)

Taylor, Shawn C.

2011-01-01

A noncontacting, two-dimensional (2-D) laser inspection system has been designed and implemented to dimensionally profile thermal barriers being developed for space vehicle applications. In a vehicle as-installed state, thermal barriers are commonly compressed between load sensitive thermal protection system (TPS) panels to prevent hot gas ingestion through the panel interface during flight. Loads required to compress the thermal barriers are functions of their construction, as well as their dimensional characteristics relative to the gaps in which they are installed. Excessive loads during a mission could damage surrounding TPS panels and have catastrophic consequences. As such, accurate dimensional profiling of thermal barriers prior to use is important. Due to the compliant nature of the thermal barriers, traditional contact measurement techniques (e.g., calipers and micrometers) are subjective and introduce significant error and variability into collected dimensional data. Implementation of a laser inspection system significantly enhanced the method by which thermal barriers are dimensionally profiled, and improved the accuracy and repeatability of collected data. A statistical design of experiments study comparing laser inspection and manual caliper measurement techniques verified these findings.

Advances in Geologic Disposal System Modeling and Application to Crystalline Rock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mariner, Paul E.; Stein, Emily R.; Frederick, Jennifer M.

The Used Fuel Disposition Campaign (UFDC) of the U.S. Department of Energy (DOE) Office of Nuclear Energy (NE), Office of Fuel Cycle Technology (OFCT) is conducting research and development (R&D) on geologic disposal of used nuclear fuel (UNF) and high-level nuclear waste (HLW). Two of the high priorities for UFDC disposal R&D are design concept development and disposal system modeling (DOE 2011). These priorities are directly addressed in the UFDC Generic Disposal Systems Analysis (GDSA) work package, which is charged with developing a disposal system modeling and analysis capability for evaluating disposal system performance for nuclear waste in geologic mediamore » (e.g., salt, granite, clay, and deep borehole disposal). This report describes specific GDSA activities in fiscal year 2016 (FY 2016) toward the development of the enhanced disposal system modeling and analysis capability for geologic disposal of nuclear waste. The GDSA framework employs the PFLOTRAN thermal-hydrologic-chemical multi-physics code and the Dakota uncertainty sampling and propagation code. Each code is designed for massively-parallel processing in a high-performance computing (HPC) environment. Multi-physics representations in PFLOTRAN are used to simulate various coupled processes including heat flow, fluid flow, waste dissolution, radionuclide release, radionuclide decay and ingrowth, precipitation and dissolution of secondary phases, and radionuclide transport through engineered barriers and natural geologic barriers to the biosphere. Dakota is used to generate sets of representative realizations and to analyze parameter sensitivity.« less

Structural Design Strategies for Improved Small Overlap Crashworthiness Performance.

PubMed

Mueller, Becky C; Brethwaite, Andrew S; Zuby, David S; Nolan, Joseph M

2014-11-01

In 2012, the Insurance Institute for Highway Safety (IIHS) began a 64 km/h small overlap frontal crash test consumer information test program. Thirteen automakers already have redesigned models to improve test performance. One or more distinct strategies are evident in these redesigns: reinforcement of the occupant compartment, use of energy-absorbing fender structures, and the addition of engagement structures to induce vehicle lateral translation. Each strategy influences vehicle kinematics, posing additional challenges for the restraint systems. The objective of this two-part study was to examine how vehicles were modified to improve small overlap test performance and then to examine how these modifications affect dummy response and restraint system performance. Among eight models tested before and after design changes, occupant compartment intrusion reductions ranged from 6 cm to 45 cm, with the highest reductions observed in models with the largest number of modifications. All redesigns included additional occupant compartment reinforcement, one-third added structures to engage the barrier, and two modified a shotgun load path. Designs with engagement structures produced greater glance-off from the barrier and exhibited lower delta Vs but experienced more lateral outboard motion of the dummy. Designs with heavy reinforcement of the occupant compartment had higher vehicle accelerations and delta V. In three cases, these apparent trade-offs were not well addressed by concurrent changes in restraint systems and resulted in increased injury risk compared with the original tests. Among the 36 models tested after design changes, the extent of design changes correlated to structural performance. Half of the vehicles with the lowest intrusion levels incorporated aspects of all three design strategies. Vehicle kinematics and dummy and restraint system characteristics were similar to those observed in the before/after pairs. Different combinations of structural improvement strategies for improving small overlap test performance were found to be effective in reducing occupant compartment intrusion and improving dummy kinematics in the IIHS small overlap test with modest weight increase.

77 FR 23303 - Self-Regulatory Organizations; NYSE Arca, Inc.; Notice of Filing and Immediate Effectiveness of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-18

... the Order Audit Trail System Information Barriers Put Into Place by the ETP Holder in Reliance on... report to the Order Audit Trail System (``OATS'') information barriers put into place by the ETP Holder... uses an effective system of internal controls--such as appropriate information barriers--that operate...

Heart failure services in the United Kingdom: rethinking the machine bureaucracy.

PubMed

Hawkins, Nathaniel M; Wright, David J; Capewell, Simon

2013-01-20

Poor outcomes and poor uptake of evidence based therapies persist for patients with heart failure in the United Kingdom. We offer a strategic analysis of services, defining the context, organization and objectives of the service, before focusing on implementation and performance. Critical flaws in past service development and performance are apparent, a consequence of failed performance management, policy and political initiative. The barriers to change and potential solutions are common to many health care systems. Integration, information, financing, incentives, innovation and values: all must be challenged and improved if heart failure services are to succeed. Modern healthcare requires open adaptive systems, continually learning and improving. The system also needs controls. Performance indicators should be simple, clinically relevant, and outcome focused. Heart failure presents one of the greatest opportunities to improve symptoms and survival with existing technology. To do so, heart failure services require radical reorganization. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Enzyme as catalytic wheel powered by a Markovian engine: conformational coupling and barrier surfing models

NASA Astrophysics Data System (ADS)

Tsong, Tian Yow; Chang, Cheng-Hung

2005-05-01

We examine a typical Michaelis-Menten Enzyme (MME) and redress it to form a transducer of free energy, and electric, acoustic, or other types of energy. This amendment and extension is necessary in lieu of recent experiments in which enzymes are shown to perform pump, motor, and locomotion functions resembling their macroscopic counterparts. Classical textbook depicts enzyme, or an MME, as biocatalyst which can enhance the rate of a chemical reaction by lowering the activation barrier but cannot shift the thermodynamic equilibrium of the biochemical reaction. An energy transducer, on the other hand, must also be able to harvest, store, or divert energy and in doing so alter the chemical equilibrium, change the energy form, fuel an energy consuming process, or perform all these functions stepwise in one catalytic turnover. The catalytic wheel presented in this communication is both a catalyst and an energy transducer and can perform all these tasks with ease. A Conformational Coupling Model for the rotary motors and a Barrier Surfing Model for the track-guided stepping motors and transporters, are presented and compared. It is shown that the core engine of the catalytic wheel, or a Brownian motor, is a Markovian engine. It remains to be seen if this core engine is the basic mechanism for a wide variety of bio-molecular energy transducers, as well as certain other dynamic systems, for example, the Parrondo's Games.

Understanding Barriers to Colorectal Cancer Screening in Kentucky.

PubMed

Knight, Jennifer Redmond; Kanotra, Sarojini; Siameh, Seth; Jones, Jessica; Thompson, Becki; Thomas-Cox, Sue

2015-06-18

Colorectal cancer screening rates have increased significantly in Kentucky, from 35% in 1999 to 66% in 2012. A continued improvement in screening requires identification of existing barriers and implementation of interventions to address barriers. The state of Kentucky added a question to the 2012 Kentucky Behavioral Risk Factor Surveillance System survey for respondents aged 50 years or older who answered no to ever having been screened for colorectal cancer by colonoscopy or sigmoidoscopy to assess the reasons why respondents had not been screened. Combined responses constituted 4 categories: attitudes and beliefs, health care provider and health care systems barriers, cost, and other. Prevalence estimates for barriers were calculated by using raking weights and were stratified by race/ethnicity, sex, education, income, and health insurance coverage. Logistic regression estimated odds ratios for barriers to screening. The most common barriers in all areas were related to attitudes and beliefs, followed by health care provider and systems, and cost. Non-Hispanic whites and respondents with more than a high school education were more likely to choose attitudes and beliefs as a barrier than were non-Hispanic blacks and those with less than a high school education. Respondents with low incomes and with no insurance were significantly more likely to select cost as a barrier. No significant associations were observed between demographic variables and the selection of a health care provider and a health care system. Barriers related to education, race/ethnicity, income, and insurance coverage should be considered when designing interventions. Expansion of Medicaid and implementation of the Affordable Care Act in Kentucky could have an impact on reducing these barriers.

High Performance MgO-barrier Magnetic Tunnel Junctions for Flexible and Wearable Spintronic Applications

PubMed Central

Chen, Jun-Yang; Lau, Yong-Chang; Coey, J. M. D.; Li, Mo; Wang, Jian-Ping

2017-01-01

The magnetic tunnel junction (MTJ) using MgO barrier is one of most important building blocks for spintronic devices and has been widely utilized as miniaturized magentic sensors. It could play an important role in wearable medical devices if they can be fabricated on flexible substrates. The required stringent fabrication processes to obtain high quality MgO-barrier MTJs, however, limit its integration with flexible electronics devices. In this work, we have developed a method to fabricate high-performance MgO-barrier MTJs directly onto ultrathin flexible silicon membrane with a thickness of 14 μm and then transfer-and-bond to plastic substrates. Remarkably, such flexible MTJs are fully functional, exhibiting a TMR ratio as high as 190% under bending radii as small as 5 mm. The devices‘ robustness is manifested by its retained excellent performance and unaltered TMR ratio after over 1000 bending cycles. The demonstrated flexible MgO-barrier MTJs opens the door to integrating high-performance spintronic devices in flexible and wearable electronics devices for a plethora of biomedical sensing applications. PMID:28150807

High Performance MgO-barrier Magnetic Tunnel Junctions for Flexible and Wearable Spintronic Applications.

PubMed

Chen, Jun-Yang; Lau, Yong-Chang; Coey, J M D; Li, Mo; Wang, Jian-Ping

2017-02-02

The magnetic tunnel junction (MTJ) using MgO barrier is one of most important building blocks for spintronic devices and has been widely utilized as miniaturized magentic sensors. It could play an important role in wearable medical devices if they can be fabricated on flexible substrates. The required stringent fabrication processes to obtain high quality MgO-barrier MTJs, however, limit its integration with flexible electronics devices. In this work, we have developed a method to fabricate high-performance MgO-barrier MTJs directly onto ultrathin flexible silicon membrane with a thickness of 14 μm and then transfer-and-bond to plastic substrates. Remarkably, such flexible MTJs are fully functional, exhibiting a TMR ratio as high as 190% under bending radii as small as 5 mm. The devices' robustness is manifested by its retained excellent performance and unaltered TMR ratio after over 1000 bending cycles. The demonstrated flexible MgO-barrier MTJs opens the door to integrating high-performance spintronic devices in flexible and wearable electronics devices for a plethora of biomedical sensing applications.

Barriers to global health development: An international quantitative survey.

PubMed

Weiss, Bahr; Pollack, Amie Alley

2017-01-01

Global health's goal of reducing low-and-middle-income country versus high-income country health disparities faces complex challenges. Although there have been discussions of barriers, there has not been a broad-based, quantitative survey of such barriers. 432 global health professionals were invited via email to participate in an online survey, with 268 (62%) participating. The survey assessed participants' (A) demographic and global health background, (B) perceptions regarding 66 barriers' seriousness, (C) detailed ratings of barriers designated most serious, (D) potential solutions. Thirty-four (of 66) barriers were seen as moderately or more serious, highlighting the widespread, significant challenges global health development faces. Perceived barrier seriousness differed significantly across domains: Resource Limitations mean = 2.47 (0-4 Likert scale), Priority Selection mean = 2.20, Corruption, Lack of Competence mean = 1.87, Social and Cultural Barriers mean = 1.68. Some system-level predictors showed significant but relatively limited relations. For instance, for Global Health Domain, HIV and Mental Health had higher levels of perceived Social and Cultural Barriers than other GH Domains. Individual-level global health experience predictors had small but significant effects, with seriousness of (a) Corruption, Lack of Competence, and (b) Priority Selection barriers positively correlated with respondents' level of LMIC-oriented (e.g., weeks/year spent in LMIC) but Academic Global Health Achievement (e.g., number of global health publications) negatively correlated with overall barrier seriousness. That comparatively few system-level predictors (e.g., Organization Type) were significant suggests these barriers may be relatively fundamental at the system-level. Individual-level and system-level effects do have policy implications; e.g., Priority Selection barriers were among the most serious, yet effects on seriousness of how LMIC-oriented a professional was versus level of academic global health achievement ran in opposite directions, suggesting increased discussion of priorities between LMIC-based and other professionals may be useful. It is hoped the 22 suggested solutions will provide useful ideas for addressing global health barriers.

Calcium carbonate-based permeable reactive barriers for iron and manganese groundwater remediation at landfills.

PubMed

Wang, Yu; Pleasant, Saraya; Jain, Pradeep; Powell, Jon; Townsend, Timothy

2016-07-01

High concentrations of iron (Fe(II)) and manganese (Mn(II)) reductively dissolved from soil minerals have been detected in groundwater monitoring wells near many municipal solid waste landfills. Two in situ permeable reactive barriers (PRBs), comprised of limestone and crushed concrete, were installed downgradient of a closed, unlined landfill in Florida, USA, to remediate groundwater containing high concentrations of these metals. Influent groundwater to the PRBs contained mean Fe and Mn concentrations of approximately 30mg/L and 1.62mg/L, respectively. PRBs were constructed in the shallow aquifer (maximum depth 4.6m below land surface) and groundwater was sampled from a network of nearby monitoring wells to evaluate barrier performance in removing these metals. PRBs significantly (p<0.05) removed dissolved Fe and Mn from influent groundwater; Fe was removed from influent water at average rates of 91% and 95% (by mass) for the limestone and crushed concrete PRBs, respectively, during the first year of the study. The performance of the PRBs declined after 3years of operation, with Fe removal efficiency decreasing to 64% and 61% for limestone and concrete PRBs, respectively. A comparison of water quality in shallow and deep monitoring wells showed a more dramatic performance reduction in the deeper section of the concrete PRB, which was attributed to an influx of sediment into the barrier and settling of particulates from the upper portions of the PRBs. Although removal of Fe and Mn from redox impacts was achieved with the PRBs, the short time frame of effectiveness relative to the duration of a full-scale remediation effort may limit the applicability of these systems at some landfills because of the construction costs required. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ocular Drug Delivery Barriers-Role of Nanocarriers in the Treatment of Anterior Segment Ocular Diseases.

PubMed

Bachu, Rinda Devi; Chowdhury, Pallabitha; Al-Saedi, Zahraa H F; Karla, Pradeep K; Boddu, Sai H S

2018-02-27

Ocular drug delivery is challenging due to the presence of anatomical and physiological barriers. These barriers can affect drug entry into the eye following multiple routes of administration (e.g., topical, systemic, and injectable). Topical administration in the form of eye drops is preferred for treating anterior segment diseases, as it is convenient and provides local delivery of drugs. Major concerns with topical delivery include poor drug absorption and low bioavailability. To improve the bioavailability of topically administered drugs, novel drug delivery systems are being investigated. Nanocarrier delivery systems demonstrate enhanced drug permeation and prolonged drug release. This review provides an overview of ocular barriers to anterior segment delivery, along with ways to overcome these barriers using nanocarrier systems. The disposition of nanocarriers following topical administration, their safety, toxicity and clinical trials involving nanocarrier systems are also discussed.

Technical and Economical Aspects of Current Thermal Barrier Coating Systems for Gas Turbine Engines by Thermal Spray and EBPVD: A Review

NASA Astrophysics Data System (ADS)

Feuerstein, Albert; Knapp, James; Taylor, Thomas; Ashary, Adil; Bolcavage, Ann; Hitchman, Neil

2008-06-01

The most advanced thermal barrier coating (TBC) systems for aircraft engine and power generation hot section components consist of electron beam physical vapor deposition (EBPVD) applied yttria-stabilized zirconia and platinum modified diffusion aluminide bond coating. Thermally sprayed ceramic and MCrAlY bond coatings, however, are still used extensively for combustors and power generation blades and vanes. This article highlights the key features of plasma spray and HVOF, diffusion aluminizing, and EBPVD coating processes. The coating characteristics of thermally sprayed MCrAlY bond coat as well as low density and dense vertically cracked (DVC) Zircoat TBC are described. Essential features of a typical EBPVD TBC coating system, consisting of a diffusion aluminide and a columnar TBC, are also presented. The major coating cost elements such as material, equipment and processing are explained for the different technologies, with a performance and cost comparison given for selected examples.

Intravital imaging of a pulmonary endothelial surface layer in a murine sepsis model.

PubMed

Park, Inwon; Choe, Kibaek; Seo, Howon; Hwang, Yoonha; Song, Eunjoo; Ahn, Jinhyo; Hwan Jo, You; Kim, Pilhan

2018-05-01

Direct intravital imaging of an endothelial surface layer (ESL) in pulmonary microcirculation could be a valuable approach to investigate the role of a vascular endothelial barrier in various pathological conditions. Despite its importance as a marker of endothelial cell damage and impairment of the vascular system, in vivo visualization of ESL has remained a challenging technical issue. In this work, we implemented a pulmonary microcirculation imaging system integrated to a custom-design video-rate laser scanning confocal microscopy platform. Using the system, a real-time cellular-level microscopic imaging of the lung was successfully performed, which facilitated a clear identification of individual flowing erythrocytes in pulmonary capillaries. Subcellular level pulmonary ESL was identified in vivo by fluorescence angiography using a dextran conjugated fluorophore to label blood plasma and the red blood cell (RBC) exclusion imaging analysis. Degradation of ESL width was directly evaluated in a murine sepsis model in vivo , suggesting an impairment of pulmonary vascular endothelium and endothelial barrier dysfunction.

Intravital imaging of a pulmonary endothelial surface layer in a murine sepsis model

PubMed Central

Park, Inwon; Choe, Kibaek; Seo, Howon; Hwang, Yoonha; Song, Eunjoo; Ahn, Jinhyo; Hwan Jo, You; Kim, Pilhan

2018-01-01

Direct intravital imaging of an endothelial surface layer (ESL) in pulmonary microcirculation could be a valuable approach to investigate the role of a vascular endothelial barrier in various pathological conditions. Despite its importance as a marker of endothelial cell damage and impairment of the vascular system, in vivo visualization of ESL has remained a challenging technical issue. In this work, we implemented a pulmonary microcirculation imaging system integrated to a custom-design video-rate laser scanning confocal microscopy platform. Using the system, a real-time cellular-level microscopic imaging of the lung was successfully performed, which facilitated a clear identification of individual flowing erythrocytes in pulmonary capillaries. Subcellular level pulmonary ESL was identified in vivo by fluorescence angiography using a dextran conjugated fluorophore to label blood plasma and the red blood cell (RBC) exclusion imaging analysis. Degradation of ESL width was directly evaluated in a murine sepsis model in vivo, suggesting an impairment of pulmonary vascular endothelium and endothelial barrier dysfunction. PMID:29760995

Barriers to wider adoption of mobile telerobotic surgery: engineering, clinical and business challenges.

PubMed

Moses, Gerald R; Doarn, Charles R

2008-01-01

A portable robotic telesurgery network could remove the geographic disparity of surgical care and provide expert surgical support for first responders to traumatic injury. This is particularly relevant to battlefield medicine where surgical intervention is currently not available to the most perilous fighting circumstances. Similar utility applies to the peacetime healthcare mission. The authors identify the potential advantage to healthcare from a mobile robotic telesurgery system and specify barriers to the employability and acceptance of such a system. The proposed research roadmap will describe a portable telesurgery system that represe government/industrial recognition and reward for excellent care provided by quality surgeons. The provision of expert surgical care improves the outcomes of surgical intervention by reducing errors. For example, during the common procedure of laparoscopic cholecystectomy, distributed telesurgical care could normalize surgical performance and limit major variance of surgeon outliers; such as reducing common bile duct injury to the very low rate seen with operation by proficient surgeons.

Quantum Accelerators for High-performance Computing Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Humble, Travis S.; Britt, Keith A.; Mohiyaddin, Fahd A.

We define some of the programming and system-level challenges facing the application of quantum processing to high-performance computing. Alongside barriers to physical integration, prominent differences in the execution of quantum and conventional programs challenges the intersection of these computational models. Following a brief overview of the state of the art, we discuss recent advances in programming and execution models for hybrid quantum-classical computing. We discuss a novel quantum-accelerator framework that uses specialized kernels to offload select workloads while integrating with existing computing infrastructure. We elaborate on the role of the host operating system to manage these unique accelerator resources, themore » prospects for deploying quantum modules, and the requirements placed on the language hierarchy connecting these different system components. We draw on recent advances in the modeling and simulation of quantum computing systems with the development of architectures for hybrid high-performance computing systems and the realization of software stacks for controlling quantum devices. Finally, we present simulation results that describe the expected system-level behavior of high-performance computing systems composed from compute nodes with quantum processing units. We describe performance for these hybrid systems in terms of time-to-solution, accuracy, and energy consumption, and we use simple application examples to estimate the performance advantage of quantum acceleration.« less

REVIEW OF MECHANISTIC UNDERSTANDING AND MODELING AND UNCERTAINTY ANALYSIS METHODS FOR PREDICTING CEMENTITIOUS BARRIER PERFORMANCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Langton, C.; Kosson, D.

2009-11-30

Cementitious barriers for nuclear applications are one of the primary controls for preventing or limiting radionuclide release into the environment. At the present time, performance and risk assessments do not fully incorporate the effectiveness of engineered barriers because the processes that influence performance are coupled and complicated. Better understanding the behavior of cementitious barriers is necessary to evaluate and improve the design of materials and structures used for radioactive waste containment, life extension of current nuclear facilities, and design of future nuclear facilities, including those needed for nuclear fuel storage and processing, nuclear power production and waste management. The focusmore » of the Cementitious Barriers Partnership (CBP) literature review is to document the current level of knowledge with respect to: (1) mechanisms and processes that directly influence the performance of cementitious materials (2) methodologies for modeling the performance of these mechanisms and processes and (3) approaches to addressing and quantifying uncertainties associated with performance predictions. This will serve as an important reference document for the professional community responsible for the design and performance assessment of cementitious materials in nuclear applications. This review also provides a multi-disciplinary foundation for identification, research, development and demonstration of improvements in conceptual understanding, measurements and performance modeling that would be lead to significant reductions in the uncertainties and improved confidence in the estimating the long-term performance of cementitious materials in nuclear applications. This report identifies: (1) technology gaps that may be filled by the CBP project and also (2) information and computational methods that are in currently being applied in related fields but have not yet been incorporated into performance assessments of cementitious barriers. The various chapters contain both a description of the mechanism or and a discussion of the current approaches to modeling the phenomena.« less

In situ retreival of contaminants or other substances using a barrier system and leaching solutions and components, processes and methods relating thereto

DOEpatents

Nickelson, Reva A.; Walsh, Stephanie; Richardson, John G.; Dick, John R.; Sloan, Paul A.

2005-06-28

Processes and methods relating to treating contaminants and collecting desired substances from a zone of interest using subterranean collection and containment barriers. Tubular casings having interlock structures are used to create subterranean barriers for containing and treating buried waste and its effluents. The subterranean barrier includes an effluent collection system. Treatment solutions provided to the zone of interest pass therethrough and are collected by the barrier and treated or recovered, allowing on-site remediation. Barrier components may be used to in the treatment by collecting or removing contaminants or other materials from the zone of interest.

Method of in situ retrieval of contaminants or other substances using a barrier system and leaching solutions

DOEpatents

Nickelson, Reva A.; Walsh, Stephanie; Richardson, John G.; Dick, John R.; Sloan, Paul A.

2006-12-26

Processes and methods relating to treating contaminants and collecting desired substances from a zone of interest using subterranean collection and containment barriers. Tubular casings having interlock structures are used to create subterranean barriers for containing and treating buried waste and its effluents. The subterranean barrier includes an effluent collection system. Treatment solutions provided to the zone of interest pass therethrough and are collected by the barrier and treated or recovered, allowing on-site remediation. Barrier components may be used to in the treatment by collecting or removing contaminants or other materials from the zone of interest.

Barriers to Asthma Management as Identified by School Nurses

ERIC Educational Resources Information Center

Quaranta, Judith E.; Spencer, Gale A.

2016-01-01

Asthma rates are increasing in children. School nurses have opportunities to care for children with asthma but need to overcome barriers impacting their ability to manage asthma in the school setting. This study (a) assessed barriers present in the school setting, (b) determined the impact of barriers on performance of asthma management behaviors,…

Energy barriers, entropy barriers, and non-Arrhenius behavior in a minimal glassy model.

PubMed

Du, Xin; Weeks, Eric R

2016-06-01

We study glassy dynamics using a simulation of three soft Brownian particles confined to a two-dimensional circular region. If the circular region is large, the disks freely rearrange, but rearrangements are rarer for smaller system sizes. We directly measure a one-dimensional free-energy landscape characterizing the dynamics. This landscape has two local minima corresponding to the two distinct disk configurations, separated by a free-energy barrier that governs the rearrangement rate. We study several different interaction potentials and demonstrate that the free-energy barrier is composed of a potential-energy barrier and an entropic barrier. The heights of both of these barriers depend on temperature and system size, demonstrating how non-Arrhenius behavior can arise close to the glass transition.

Space-Based Information Infrastructure Architecture for Broadband Services

NASA Technical Reports Server (NTRS)

Price, Kent M.; Inukai, Tom; Razdan, Rajendev; Lazeav, Yvonne M.

1996-01-01

This study addressed four tasks: (1) identify satellite-addressable information infrastructure markets; (2) perform network analysis for space-based information infrastructure; (3) develop conceptual architectures; and (4) economic assessment of architectures. The report concludes that satellites will have a major role in the national and global information infrastructure, requiring seamless integration between terrestrial and satellite networks. The proposed LEO, MEO, and GEO satellite systems have satellite characteristics that vary widely. They include delay, delay variations, poorer link quality and beam/satellite handover. The barriers against seamless interoperability between satellite and terrestrial networks are discussed. These barriers are the lack of compatible parameters, standards and protocols, which are presently being evaluated and reduced.

Shopping For Danger: E-commerce techniques applied to collaboration in cyber security

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruce, Joseph R.; Fink, Glenn A.

Collaboration among cyber security analysts is essential to a successful protection strategy on the Internet today, but it is uncommonly practiced or encouraged in operating environments. Barriers to productive collaboration often include data sensitivity, time and effort to communicate, institutional policy, and protection of domain knowledge. We propose an ambient collaboration framework, Vulcan, designed to remove the barriers of time and effort and mitigate the others. Vulcan automated data collection, collaborative filtering, and asynchronous dissemination, eliminating the effort implied by explicit collaboration among peers. We instrumented two analytic applications and performed a mock analysis session to build a dataset andmore » test the output of the system.« less

Associations between health-related quality of life and financial barriers to care among women veterans and women non-veterans.

PubMed

Shen, Chan; Sambamoorthi, Usha

2012-01-01

The authors of this study examined the association between health-related quality of life and financial barriers to care, defined as not getting the needed care due to cost considerations. To better understand health-related quality of life among women veterans, the authors compared women veterans to women non-veterans. The authors conducted cross-sectional analyses using data from the 2009 Behavioral Risk Factor Surveillance System survey. The authors assessed four health-related quality of life measures: (1) general health; (2) physical health; (3) mental health; and (4) functional status. The authors performed multinomial logistic regressions to examine the relationship between financial barriers to receiving healthcare and health-related quality of life measures after controlling for other independent variables. The authors included women veterans not in active military duty (N = 3,747) and a matched sample of women non-veterans (N = 3,747), selected using a propensity score method so that they would have distributions of demographic and socioeconomic characteristics similar to those of the veterans. Overall, 14% of women reported financial barriers. Women who reported financial barriers to receiving healthcare were more likely to have poor health-related quality of life in all four dimensions than those who did not report such barriers. Compared to women non-veterans, women veterans did not differ in reported financial barriers but were more likely to report poor health-related quality of life. Reporting financial barriers to receiving needed healthcare was significantly associated with poor health-related quality of life among women. Veteran status was also significantly associated with poor health-related quality of life. These findings suggest the need for healthcare policy makers and practitioners to align emerging new models of healthcare delivery to improve health-related quality of life for women veterans.

Incentives and Barriers That Influence Clinical Computerization in Hong Kong: A Population-based Physician Survey

PubMed Central

Leung, Gabriel M.; Yu, Philip L. H.; Wong, Irene O. L.; Johnston, Janice M.; Tin, Keith Y. K.

2003-01-01

Objective: Given the slow adoption of medical informatics in Hong Kong and Asia, we sought to understand the contributory barriers and potential incentives associated with information technology implementation. Design and Measurements: A representative sample of 949 doctors (response rate = 77.0%) was asked through a postal survey to rank a list of nine barriers associated with clinical computerization according to self-perceived importance. They ranked seven incentives or catalysts that may influence computerization. We generated mean rank scores and used multidimensional preference analysis to explore key explanatory dimensions of these variables. A hierarchical cluster analysis was performed to identify homogenous subgroups of respondents. We further determined the relationships between the sets of barriers and incentives/catalysts collectively using canonical correlation. Results: Time costs, lack of technical support and large capital investments were the biggest barriers to computerization, whereas improved office efficiency and better-quality care were ranked highest as potential incentives to computerize. Cost vs. noncost, physician-related vs. patient-related, and monetary vs. nonmonetary factors were the key dimensions explaining the barrier variables. Similarly, within-practice vs external and “push” vs “pull” factors accounted for the incentive variables. Four clusters were identified for barriers and three for incentives/catalysts. Canonical correlation revealed that respondents who were concerned with the costs of computerization also perceived financial incentives and government regulation to be important incentives/catalysts toward computerization. Those who found the potential interference with communication important also believed that the promise of improved care from computerization to be a significant incentive. Conclusion: This study provided evidence regarding common barriers associated with clinical computerization. Our findings also identified possible incentive strategies that may be employed to accelerate uptake of computer systems. PMID:12595409

Railroad retarder noise reduction : study of acoustical barrier configurations

DOT National Transportation Integrated Search

1979-05-01

Field measurements of noise were made near a railroad retarder system without barriers and with acoustical barriers of various configurations. The configurations tested included acoustically reflective and acoustically absorptive barriers with height...

Smart Building: Decision Making Architecture for Thermal Energy Management.

PubMed

Uribe, Oscar Hernández; Martin, Juan Pablo San; Garcia-Alegre, María C; Santos, Matilde; Guinea, Domingo

2015-10-30

Smart applications of the Internet of Things are improving the performance of buildings, reducing energy demand. Local and smart networks, soft computing methodologies, machine intelligence algorithms and pervasive sensors are some of the basics of energy optimization strategies developed for the benefit of environmental sustainability and user comfort. This work presents a distributed sensor-processor-communication decision-making architecture to improve the acquisition, storage and transfer of thermal energy in buildings. The developed system is implemented in a near Zero-Energy Building (nZEB) prototype equipped with a built-in thermal solar collector, where optical properties are analysed; a low enthalpy geothermal accumulation system, segmented in different temperature zones; and an envelope that includes a dynamic thermal barrier. An intelligent control of this dynamic thermal barrier is applied to reduce the thermal energy demand (heating and cooling) caused by daily and seasonal weather variations. Simulations and experimental results are presented to highlight the nZEB thermal energy reduction.

Effects of compositional changes on the performance of a thermal barrier coating system. [yttria-stabilized zirconia coatings on gas turbine engine blades

NASA Technical Reports Server (NTRS)

Stecura, S.

1978-01-01

Currently proposed thermal barrier systems for aircraft gas turbine engines consist of NiCrAlY bond coating covered with an insulating oxide layer of yttria-stabilized zirconia. The effect of yttrium concentration (from 0.15 to 1.08 w/o) in the bond coating and the yttria concentration (4 to 24.4 w/o) in the oxide layer were evaluated. Furnace, natural gas-oxygen torch, and Mach 1.0 burner rig cyclic tests on solid specimens and air-cooled blades were used to identify trends in coating behavior. Results indicate that the combinations of yttrium levels between 0.15 - 0.35 w/o in the bond coating and the yttria concentration between 6 - 8 w/o in the zirconium oxide layer were the most adherent and resistant to high temperature cyclic exposure.

The Development of Environmental Barrier Coating Systems for SiC-SiC Ceramic Matrix Composites: Environment Effects on the Creep and Fatigue Resistance

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Ghosn, Louis J.

2014-01-01

Topics covered include: Environmental barrier coating system development: needs, challenges and limitations; Advanced environmental barrier coating systems (EBCs) for CMC airfoils and combustors; NASA EBC systems and material system evolutions, Current turbine and combustor EBC coating emphases, Advanced development, processing, testing and modeling, EBC and EBC bond coats: recent advances; Design tool and life prediction of coated CMC components; Advanced CMC-EBC rig demonstrations; Summary and future directions.

Regenerative switching CMOS system

DOEpatents

Welch, James D.

1998-01-01

Complementary Metal Oxide Semiconductor (CMOS) Schottky barrier Field Effect Transistor systems, which are a seriesed combination of N and P-Channel MOSFETS, in which Source Schottky barrier junctions of the N and P-Channel Schottky barrier MOSFETS are electically interconnected, (rather than the Drains as in conventional diffused junction CMOS), which Schottky barrier MOSFET system demonstrates Regenerative Inverting Switching Characteristics in use are disclosed. Both the N and P-Channel Schottky barrier MOSFET devices are unique in that they provide operational Drain Current vs. Drain to Source voltage as a function of Gate voltage only where the polarities of the Drain voltage and Gate voltage are opposite, referenced to the Source as a common terminal, and where the polarity of the voltage applied to the Gate is appropriate to cause Channel inversion. Experimentally derived results which demonstrate and verify the operation of N and P-Channel Schottky barrier MOSFETS actually fabricated on P and N-type Silicon respectively, by a common procedure using vacuum deposited Chromium as a Schottky barrier forming metal, are also provided.

Regenerative switching CMOS system

DOEpatents

Welch, J.D.

1998-06-02

Complementary Metal Oxide Semiconductor (CMOS) Schottky barrier Field Effect Transistor systems, which are a series combination of N and P-Channel MOSFETS, in which Source Schottky barrier junctions of the N and P-Channel Schottky barrier MOSFETS are electrically interconnected, (rather than the Drains as in conventional diffused junction CMOS), which Schottky barrier MOSFET system demonstrates Regenerative Inverting Switching Characteristics in use are disclosed. Both the N and P-Channel Schottky barrier MOSFET devices are unique in that they provide operational Drain Current vs. Drain to Source voltage as a function of Gate voltage only where the polarities of the Drain voltage and Gate voltage are opposite, referenced to the Source as a common terminal, and where the polarity of the voltage applied to the Gate is appropriate to cause Channel inversion. Experimentally derived results which demonstrate and verify the operation of N and P-Channel Schottky barrier MOSFETS actually fabricated on P and N-type Silicon respectively, by a common procedure using vacuum deposited Chromium as a Schottky barrier forming metal, are also provided. 14 figs.

Problems with the performance of wooden noise barriers.

DOT National Transportation Integrated Search

1984-01-01

In September 1984, the Research Council was requested by the Virginia Department of Highways and Transportation to conduct an investigation into the problems experienced with wooden noise barriers. Some of these barriers warped even before constructi...

Cost And Performance Report Evaluating the Longevity and Hydraulic Performance of Permeable Reactive Barriers at Department of Defense Sites

DTIC Science & Technology

2003-12-01

construction methods, such as jetting, hydraulic fracturing , and vibratory beam, have been demonstrated at some sites, as they offer some cost... hydraulic fracturing , are available, but there is not as much widespread experience yet with these techniques for PRBs. Also, these innovative... hydraulic fracturing ) can be used at relatively higher cost. The cost comparison of a PRB versus an active remedy, such as a pump-and-treat system, often

Comparative study on the deposition of silicon oxide permeation barrier coatings for polymers using hexamethyldisilazane (HMDSN) and hexamethyldisiloxane (HMDSO)

NASA Astrophysics Data System (ADS)

Mitschker, F.; Schücke, L.; Hoppe, Ch; Jaritz, M.; Dahlmann, R.; de los Arcos, T.; Hopmann, Ch; Grundmeier, G.; Awakowicz, P.

2018-06-01

The effect of the selection of hexamethyldisiloxane (HMDSO) and hexamethyldisilazane (HMDSN) as a precursor in a microwave driven low pressure plasma on the deposition of silicon oxide barrier coatings and silicon based organic interlayers on polyethylene terephthalate (PET) and polypropylene (PP) substrates is investigated. Mass spectrometry is used to quantify the absolute gas density and the degree of depletion of neutral precursor molecules under variation of oxygen admixture. On average, HMDSN shows a smaller density, a higher depletion and the production of smaller fragments. Subsequently, this is correlated with barrier performance and chemical structure as a function of barrier layer thickness and oxygen admixture on PET. For this purpose, the oxygen transmission rate (OTR) is measured and Fourier transformed infrared (FTIR) spectroscopy as well as x-ray photoelectron spectroscopy (XPS) is performed. HMDSN based coatings exhibit significantly higher barrier performances for high admixtures of oxygen (200 sccm). In comparison to HMDSO based processes, however, a higher supply of oxygen is necessary to achieve a sufficient degree of oxidation, cross-linking and, therefore, barrier performance. FTIR and XPS reveal a distinct carbon content for low oxygen admixtures (10 and 20 sccm) in case of HMDSN based coatings. The variation of interlayer thickness also reveals significantly higher OTR for HMDSO based coatings on PET and PP. Barrier performance of HMDSO based coatings improves with increasing interlayer thickness up to 10 nm for PET and PP. HMDSN based coatings exhibit a minimum of OTR without interlayer on PP and for 2 nm interlayer thickness on PET. Furthermore, HMDSN based coatings show distinctly higher bond strengths to the PP substrate.

The Expanded Capabilities Of The Cementitious Barriers Partnership Software Toolbox Version 2.0 - 14331

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burns, Heather; Flach, Greg; Smith, Frank

2014-01-10

The Cementitious Barriers Partnership (CBP) Project is a multi-disciplinary, multi-institutional collaboration supported by the U.S. Department of Energy (US DOE) Office of Tank Waste Management. The CBP program has developed a set of integrated tools (based on state-of-the-art models and leaching test methods) that help improve understanding and predictions of the long-term structural, hydraulic and chemical performance of cementitious barriers used in nuclear applications. The CBP Software Toolbox – “Version 1.0” was released early in FY2013 and was used to support DOE-EM performance assessments in evaluating various degradation mechanisms that included sulfate attack, carbonation and constituent leaching. The sulfate attackmore » analysis predicted the extent and damage that sulfate ingress will have on concrete vaults over extended time (i.e., > 1000 years) and the carbonation analysis provided concrete degradation predictions from rebar corrosion. The new release “Version 2.0” includes upgraded carbonation software and a new software module to evaluate degradation due to chloride attack. Also included in the newer version are a dual regime module allowing evaluation of contaminant release in two regimes – both fractured and un-fractured. The integrated software package has also been upgraded with new plotting capabilities and many other features that increase the “user-friendliness” of the package. Experimental work has been generated to provide data to calibrate the models to improve the credibility of the analysis and reduce the uncertainty. Tools selected for and developed under this program have been used to evaluate and predict the behavior of cementitious barriers used in near-surface engineered waste disposal systems for periods of performance up to or longer than 100 years for operating facilities and longer than 1000 years for waste disposal. The CBP Software Toolbox is and will continue to produce tangible benefits to the working DOE Performance Assessment (PA) community.« less

Barriers to global health development: An international quantitative survey

PubMed Central

2017-01-01

Background Global health’s goal of reducing low-and-middle-income country versus high-income country health disparities faces complex challenges. Although there have been discussions of barriers, there has not been a broad-based, quantitative survey of such barriers. Methods 432 global health professionals were invited via email to participate in an online survey, with 268 (62%) participating. The survey assessed participants’ (A) demographic and global health background, (B) perceptions regarding 66 barriers’ seriousness, (C) detailed ratings of barriers designated most serious, (D) potential solutions. Results Thirty-four (of 66) barriers were seen as moderately or more serious, highlighting the widespread, significant challenges global health development faces. Perceived barrier seriousness differed significantly across domains: Resource Limitations mean = 2.47 (0–4 Likert scale), Priority Selection mean = 2.20, Corruption, Lack of Competence mean = 1.87, Social and Cultural Barriers mean = 1.68. Some system-level predictors showed significant but relatively limited relations. For instance, for Global Health Domain, HIV and Mental Health had higher levels of perceived Social and Cultural Barriers than other GH Domains. Individual–level global health experience predictors had small but significant effects, with seriousness of (a) Corruption, Lack of Competence, and (b) Priority Selection barriers positively correlated with respondents’ level of LMIC-oriented (e.g., weeks/year spent in LMIC) but Academic Global Health Achievement (e.g., number of global health publications) negatively correlated with overall barrier seriousness. Conclusions That comparatively few system-level predictors (e.g., Organization Type) were significant suggests these barriers may be relatively fundamental at the system-level. Individual-level and system-level effects do have policy implications; e.g., Priority Selection barriers were among the most serious, yet effects on seriousness of how LMIC-oriented a professional was versus level of academic global health achievement ran in opposite directions, suggesting increased discussion of priorities between LMIC-based and other professionals may be useful. It is hoped the 22 suggested solutions will provide useful ideas for addressing global health barriers. PMID:28972971

Unabsorbed polylactide adhesion barrier mimicking recurrence of gynecologic malignant diseases with increased ¹⁸F-FDG uptake on PET/CT.

PubMed

Chong, Gun Oh; Lee, Yoon Hee; Hong, Dae Gy; Cho, Young Lae; Lee, Yoon Soon

2015-07-01

To evaluate the incidence and characteristics of the unabsorbed polylactide adhesion barrier with increased (18)F-fluorodeoxyglucose ((18)F-FDG) uptake after surgeries for gynecologic malignancies. Between September 2006 and November 2009, we reviewed the charts of 75 patients who were provided a polylactide adhesion barrier after surgery for gynecologic malignant diseases. We surveyed the cases of increased (18)F-FDG uptake on positron emission tomography/computed tomography (PET/CT), and evaluated the effectiveness of polylactide adhesion barrier using an adhesion scoring system. Ten patients (13.3 %) had a solitary pelvic mass with increased (18)F-FDG uptake in the follow up PET/CT. The characteristics of patients and tumors are described below. The median age was 48 years (range 19-66 years). The median tumor size was 1.9 cm (range 1.0-2.3 cm), and the median SUVmax of the pelvic mass was 5.1 (range 3.7-7.9). The median time between initial operations and second operation was 13.5 months (range 8-23 months). We performed laparoscopic excision of the pelvic mass, and the biopsy revealed foreign body reactions with the exception of 1 case, which contained tumor cells under the unabsorbed polylactide adhesion barrier. The median adhesion grade was 1 (range 0-2). A solitary pelvic mass found in the PET/CT with increased (18)F-FDG uptake after usage of a polylactide adhesion barrier may be an unabsorbed remnant. The adhesion barrier should be used with caution in patients with gynecologic malignant diseases.

Physician's perceived roles, as well as barriers, towards caring for women sex assault survivors

PubMed Central

Amin, Priyanka; Buranosky, Raquel; Chang, Judy C.

2016-01-01

Background Sexual assault (SA) affects about 40% of women in the US and has many mental and physical health sequelae. Physicians often do not address SA with patients although SA survivors describe a desire to talk to physicians to obtain additional help. Little information exists on how providers perceive their roles regarding caring for women SA survivors and what barriers they face in providing this care. Methods We performed a qualitative study using semi-structured one-on-one interviews with sixteen faculty physicians from five specialties: obstetrics and gynecology (four), internal medicine (four), family medicine (one), emergency medicine (three), and psychiatry (four). Interviews were conducted between July 2011 and July 2012, transcribed verbatim, and coded using a constant comparative approach. Once a final coding scheme was applied to all transcripts, we identified patterns and themes related to perceived roles and barriers to caring for SA survivors. Results Physicians described two main categories of roles: clinical tasks (e.g. testing and treating for sexually transmitted infections, managing associated mental health sequelae) and interpersonal roles (e.g. providing support, acting as patient advocate). Physician barriers fell into three main categories: (1) internal barriers (e.g. discomfort with the topic of SA); (2) physician-patient communication; and (3) system obstacles (e.g. competing priorities for time). Conclusions Although physicians describe key roles in caring for SA survivors, several barriers hinder their ability to fulfill these roles. Training interventions are needed to reduce the barriers that would ultimately improve clinical care for SA survivors. PMID:27863981

Solar energy in buildings: Implications for California energy policy

NASA Technical Reports Server (NTRS)

Hirshberg, A. S.; Davis, E. S.

1977-01-01

An assessment of the potential of active solar energy systems for buildings in California is summarized. The technology used for solar heating, cooling, and water heating in buildings is discussed. The major California weather zones and the solar energy designs are described, as well as the sizing of solar energy systems and their performance. The cost of solar energy systems is given both at current prices and at prices consistent with optimistic estimates for the cost of collectors. The main institutional barriers to the wide spread use of solar energy are summarized.

Splaying of aliphatic tails plays a central role in barrier crossing during liposome fusion.

PubMed

Mirjanian, Dina; Dickey, Allison N; Hoh, Jan H; Woolf, Thomas B; Stevens, Mark J

2010-09-02

The fusion between two lipid bilayers involves crossing a complicated energy landscape. The limiting barrier in the process appears to be between two closely opposed bilayers and the intermediate state where the outer leaflets are fused. We have performed molecular dynamics simulations to characterize the free energy barrier for the fusion of two liposomes and to examine the molecular details of barrier crossing. To capture the slow dynamics of fusion, a model using coarse-grained representations of lipids was used. The fusion between pairs of liposomes was simulated for four systems: DPPC, DOPC, a 3:1 mixture of DPPC/DPPE, and an asymmetric lipid tail system in which one tail of DPPC was reduced to half the length (ASTail). The weighted histogram method was used to compute the free energy as a function of separation distance. The relative barrier heights for these systems was found to be ASTail > DPPC > DPPC/DPPE > DOPC, in agreement with experimental observations. Further, the free energy curves for all four can be overlaid on a single curve by plotting the free energy versus the surface separation (differing only in the point of fusion). These simulations also confirm that the two main contributions to the free energy barrier are the removal of water between the vesicles and the deformation of the vesicle. The most prominent molecular detail of barrier crossing in all cases examined was the splaying of lipid tails, where initially a single splayed lipid formed a bridge between the two outer leaflets that promotes additional lipid mixing between the vesicles and eventually leads to fusion. The tail splay appears to be closely connected to the energetics of the process. For example, the high barrier for the ASTail is the result of a smaller distance between terminal methyl groups in the splayed molecule. The shortening of this distance requires the liposomes to be closer together, which significantly increases the cost of water removal and bilayer deformation. Before tail splay can initiate fusion, contact must occur between a tail end and the external water. In isolated vesicles, the contact fraction is correlated to the fusogenicity difference between DPPC and DOPC. Moreover, for planar bilayers, the contact fraction is much lower for DPPC, which is consistent with its lack of fusion in giant vesicles. The simulation results show the key roles of lipid tail dynamics in governing the fusion energy landscape.

[High Pressure Gas Tanks

NASA Technical Reports Server (NTRS)

Quintana, Rolando

2002-01-01

Four high-pressure gas tanks, the basis of this study, were especially made by a private contractor and tested before being delivered to NASA Kennedy Space Center. In order to insure 100% reliability of each individual tank the staff at KSC decided to again submit the four tanks under more rigorous tests. These tests were conducted during a period from April 10 through May 8 at KSC. This application further validates the predictive safety model for accident prevention and system failure in the testing of four high-pressure gas tanks at Kennedy Space Center, called Continuous Hazard Tracking and Failure Prediction Methodology (CHTFPM). It is apparent from the variety of barriers available for a hazard control that some barriers will be more successful than others in providing protection. In order to complete the Barrier Analysis of the system, a Task Analysis and a Biomechanical Study were performed to establish the relationship between the degree of biomechanical non-conformities and the anomalies found within the system on particular joints of the body. This relationship was possible to obtain by conducting a Regression Analysis to the previously generated data. From the information derived the body segment with the lowest percentage of non-conformities was the neck flexion with 46.7%. Intense analysis of the system was conducted including Preliminary Hazard Analysis (PHA), Failure Mode and Effect Analysis (FMEA), and Barrier Analysis. These analyses resulted in the identification of occurrences of conditions, which may be becoming hazardous in the given system. These conditions, known as dendritics, may become hazards and could result in an accident, system malfunction, or unacceptable risk conditions. A total of 56 possible dendritics were identified. Work sampling was performed to observe the occurrence each dendritic. The out of control points generated from a Weighted c control chart along with a Pareto analysis indicate that the dendritics "Personnel not Wearing Proper Protective and Hose/tubing located in high-traffic area" which account for 59.18% of total dendritic frequency need to be addressed to reduce the chance of a hazard from occurring. However, the occurrences of some dendritics are more important than others. As a result immediate, from a Weighted c perspective, corrective action should be taken to ameliorate the cause of the Class A dendritic "Personnel located under suspended or moving loads" rather than just the most commonly occurring dendritics. In any case the vast majority of data obtained indicates that testing operations possess a relatively high degree of safety.

Infrasonic wind-noise reduction by barriers and spatial filters.

PubMed

Hedlin, Michael A H; Raspet, Richard

2003-09-01

This paper reports experimental observations of wind speed and infrasonic noise reduction inside a wind barrier. The barrier is compared with "rosette" spatial filters and with a reference site that uses no noise reduction system. The barrier is investigated for use at International Monitoring System (IMS) infrasound array sites where spatially extensive noise-reducing systems cannot be used because of a shortage of suitable land. Wind speed inside a 2-m-high 50%-porous hexagonal barrier coated with a fine wire mesh is reduced from ambient levels by 90%. If the infrasound wind-noise level reductions are all plotted versus the reduced frequency given by f*L/v, where L is the characteristic size of the array or barrier, f is the frequency, and v is the wind speed, the reductions at different wind speeds are observed to collapse into a single curve for each wind-noise reduction method. The reductions are minimal below a reduced frequency of 0.3 to 1, depending on the device, then spatial averaging over the turbulence structure leads to increased reduction. Above the reduced corner frequency, the barrier reduces infrasonic noise by up to 20 to 25 dB. Below the corner frequency the barrier displays a small reduction of about 4 dB. The rosettes display no reduction below the corner frequency. One other advantage of the wind barrier over rosette spatial filters is that the signal recorded inside the barrier enters the microbarometer from free air and is not integrated, possibly out of phase, after propagation through a system of narrow pipes.

Chasing boundaries and cascade effects in a coupled barrier-marsh-lagoon system

NASA Astrophysics Data System (ADS)

Lorenzo-Trueba, Jorge; Mariotti, Giulio

2017-08-01

The long-term dynamic evolution of an idealized barrier-marsh-lagoon system experiencing sea-level rise is studied by coupling two existing numerical models. The barrier model accounts for the interaction between shoreface dynamics and overwash flux, which allows the occurrence of barrier drowning. The marsh-lagoon model includes both a backbarrier marsh and an interior marsh, and accounts for the modification of the wave regime associated with changes in lagoon width and depth. Overwash, the key process that connects the barrier shoreface with the marsh-lagoon ecosystems, is formulated to account for the role of the backbarrier marsh. Model results show that a number of factors that are not typically associated with the dynamics of coastal barriers can enhance the rate of overwash-driven landward migration by increasing backbarrier accommodation space. For instance, lagoon deepening could be triggered by marsh edge retreat and consequent export of fine sediment via tidal dispersion, as well as by an expansion of inland marshes and consequent increase in accommodation space to be filled in with sediment. A deeper lagoon results in a larger fraction of sediment overwash being subaqueous, which coupled with a slow shoreface response sending sediment onshore can trigger barrier drowning. We therefore conclude that the supply of fine sediments to the back-barrier and the dynamics of both the interior and backbarrier marsh can be essential for maintaining the barrier system under elevated rates of sea-level rise. Our results highlight the importance of considering barriers and their associated backbarriers as part of an integrated system in which sediment is exchanged.

ACCUMULATION RATE OF MICROBIAL BIOMASS AT TWO PERMEABLE REACTIVE BARRIER SITES

EPA Science Inventory

Accumulation of mineral precipitates and microbial biomass are key factors that impact the long-term performance of in-situ Permeable Reactive Barriers for treating contaminated groundwater. Both processes can impact remedial performance by decreasing zero-valent iron reactivity...

Multilayer coatings for flexible high-barrier materials

NASA Astrophysics Data System (ADS)

Vaško, Karol; Noller, Klaus; Mikula, Milan; Amberg-Schwab, Sabine; Weber, Ulrike

2009-06-01

A multilayer, flexible, and transparent high-barrier system based on flexible plastic foils, polyethyleneterephthalate (PET) and ethylene-tetrafluoroethylene-copolymer (ETFE), combined with vacuum-deposited, inorganic SiOx layers and hybrid ORMOCER® varnish layers were prepared in different orders on a semiproduction level. Barrier properties of prepared systems, as water vapour transmission (WVTR) and oxygen transmission (OTR), were measured and studied in connection with surface energy, surface topography, and water vapour adsorption properties. Correlations among layers sequence, barrier properties, and other parameters are presented, including some basic principles of permeation of substances through multilayer barrier systems. A combination of several inorganic and hybrid varnish layers is necessary to achieve the technological demands from a barrier standpoint. It is easier to suppress the oxygen transport than the water transport, due to the additional active penetration of water through hydrogen bonds and silanol creations at oxide interfaces, capillary condensation, and swelling with high internal pressure, leading to new defects.

49 CFR 213.347 - Automotive or railroad crossings at grade.

Code of Federal Regulations, 2010 CFR

2010-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Train Operations at Track Classes 6 and.../barrier system to address the protection of highway traffic and high speed trains. Trains shall not...-approved warning/barrier system exists on that track segment; and (2) All elements of that warning/barrier...

36 CFR 1192.109 - Between-car barriers.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Between-car barriers. 1192... Commuter Rail Cars and Systems § 1192.109 Between-car barriers. Where vehicles operate in a high-platform, level-boarding mode, and where between-car bellows are not provided, devices or systems shall be...

36 CFR 1192.63 - Between-car barriers.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Between-car barriers. 1192.63... Rail Vehicles and Systems § 1192.63 Between-car barriers. (a) Requirement. Suitable devices or systems... between cars. Acceptable solutions include, but are not limited to, pantograph gates, chains, motion...

36 CFR 1192.63 - Between-car barriers.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Between-car barriers. 1192.63... Rail Vehicles and Systems § 1192.63 Between-car barriers. (a) Requirement. Suitable devices or systems... between cars. Acceptable solutions include, but are not limited to, pantograph gates, chains, motion...

36 CFR 1192.63 - Between-car barriers.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Between-car barriers. 1192.63... Rail Vehicles and Systems § 1192.63 Between-car barriers. (a) Requirement. Suitable devices or systems... between cars. Acceptable solutions include, but are not limited to, pantograph gates, chains, motion...

36 CFR 1192.109 - Between-car barriers.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 36 Parks, Forests, and Public Property 3 2012-07-01 2012-07-01 false Between-car barriers. 1192... Commuter Rail Cars and Systems § 1192.109 Between-car barriers. Where vehicles operate in a high-platform, level-boarding mode, and where between-car bellows are not provided, devices or systems shall be...

36 CFR 1192.109 - Between-car barriers.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 36 Parks, Forests, and Public Property 3 2014-07-01 2014-07-01 false Between-car barriers. 1192... Commuter Rail Cars and Systems § 1192.109 Between-car barriers. Where vehicles operate in a high-platform, level-boarding mode, and where between-car bellows are not provided, devices or systems shall be...

36 CFR 1192.63 - Between-car barriers.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Between-car barriers. 1192.63... Rail Vehicles and Systems § 1192.63 Between-car barriers. (a) Requirement. Suitable devices or systems... between cars. Acceptable solutions include, but are not limited to, pantograph gates, chains, motion...

36 CFR 1192.109 - Between-car barriers.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Between-car barriers. 1192... Commuter Rail Cars and Systems § 1192.109 Between-car barriers. Where vehicles operate in a high-platform, level-boarding mode, and where between-car bellows are not provided, devices or systems shall be...

Roadside barrier effectiveness : noise measurement program

DOT National Transportation Integrated Search

1978-04-01

A field noise measurement program was conducted to assess the performance of a variable height highway noise barrier with and without an acoustic lining material. The barrier site on Interstate I-93 in Andover MA was located adjacent to an acoustical...

Cost benefit of privatizing wall barrier.

DOT National Transportation Integrated Search

2007-08-01

This project began as an attempt to perform a formal comparative cost benefit analysis of privatized wall barrier purchase/management and NMDOT wall barrier purchase/management in order to answer the question "What are the costs and benefits of priva...

Reusable cryogenic foam insulation for advanced aerospace vehicles

NASA Technical Reports Server (NTRS)

Mcauliffe, Patrick S.; Taylor, Allan H.; Sparks, Larry L.; Dube, William P.

1991-01-01

Future high-speed aircraft and aerospace vehicles using cryogenic propellants will require an advanced reusable insulation system for the propellant tank structure. This cryogenic insulation system must be lightweight, structurally and thermally efficient, and capable of multiple reuse without cracking or degraded performance. This paper presents recent progress in the development of a reusable cryogenic foam insulation system having a maximum service temperature of 400 F. The system consists of preshaped, precut blocks of rigid polymethacrylimide foam insulation, wrapped with a high-temperature Kapton and aluminum foil vapor barrier which is adhesively bonded to the propellant tank wall.

A tunable acoustic barrier based on periodic arrays of subwavelength slits

NASA Astrophysics Data System (ADS)

Rubio, Constanza; Uris, Antonio; Candelas, Pilar; Belmar, Francisco; Gomez-Lozano, Vicente

2015-05-01

The most usual method to reduce undesirable enviromental noise levels during its transmission is the use of acoustic barriers. A novel type of acoustic barrier based on sound transmission through subwavelength slits is presented. This system consists of two rows of periodic repetition of vertical rigid pickets separated by a slit of subwavelength width and with a misalignment between them. Here, both the experimental and the numerical analyses are presented. The acoustic barrier proposed can be easily built and is frequency tunable. The results demonstrated that the proposed barrier can be tuned to mitigate a band noise without excesive barrier thickness. The use of this system as an environmental acoustic barrier has certain advantages with regard to the ones currently used both from the constructive and the acoustical point of view.

Delivery of Type 2 diabetes care in low- and middle-income countries: lessons from Lima, Peru.

PubMed

Cardenas, M K; Miranda, J J; Beran, D

2016-06-01

The health system's response is crucial to addressing the increasing burden of diabetes, particularly that affecting low- and middle-income countries. This study aims to assess the facilitators and barriers that help or hinder access to care for people with diabetes in Peru. We used a survey tool to design and collect qualitative and quantitative data from primary and secondary sources of information at different levels of the health system. We performed 111 interviews in Lima, the capital city of Peru, with patients with diabetes, healthcare providers and healthcare officials. We applied the six building blocks framework proposed by the World Health Organization in our analysis. We found low political commitment, as well as several barriers that directly affect access to medicines, regular laboratory check-ups and follow-up appointments for diabetes, especially at the primary healthcare level. Three major system-level barriers were identified: (1) the availability of information at different healthcare system levels that affects several processes in the healthcare provision; (2) insufficient financial resources; and (3) insufficient human resources trained in diabetes management. Despite an initial political commitment by the Peruvian government to improve the delivery of diabetes care, there exist several key limitations that affect access to adequate diabetes care, especially at the primary healthcare level. In a context in which various low- and middle-income countries are aiming to achieve universal health coverage, this study provides lessons for the implementation of strategies related to diabetes care delivery. © 2016 Diabetes UK.

Surface pre-treatment for barrier coatings on polyethylene terephthalate

NASA Astrophysics Data System (ADS)

Bahre, H.; Bahroun, K.; Behm, H.; Steves, S.; Awakowicz, P.; Böke, M.; Hopmann, Ch; Winter, J.

2013-02-01

Polymers have favourable properties such as light weight, flexibility and transparency. Consequently, this makes them suitable for food packaging, organic light-emitting diodes and flexible solar cells. Nonetheless, raw plastics do not possess sufficient barrier functionality against oxygen and water vapour, which is of paramount importance for most applications. A widespread solution is to deposit thin silicon oxide layers using plasma processes. However, silicon oxide layers do not always fulfil the requirements concerning adhesion and barrier performance when deposited on films. Thus, plasma pre-treatment is often necessary. To analyse the influence of a plasma-based pre-treatment on barrier performance, different plasma pre-treatments on three reactor setups were applied to a very smooth polyethylene terephthalate film before depositing a silicon oxide barrier layer. In this paper, the influence of oxygen and argon plasma pre-treatments towards the barrier performance is discussed examining the chemical and topological change of the film. It was observed that a short one-to-ten-second plasma treatment can reduce the oxygen transmission rate by a factor of five. The surface chemistry and the surface topography change significantly for these short treatment times, leading to an increased surface energy. The surface roughness rises slowly due to the development of small spots in the nanometre range. For very long treatment times, surface roughness of the order of the barrier layer's thickness results in a complete loss of barrier properties. During plasma pre-treatment, the trade-off between surface activation and roughening of the surface has to be carefully considered.

Reducing beam shaper alignment complexity: diagnostic techniques for alignment and tuning

NASA Astrophysics Data System (ADS)

Lizotte, Todd E.

2011-10-01

Safe and efficient optical alignment is a critical requirement for industrial laser systems used in a high volume manufacturing environment. Of specific interest is the development of techniques to align beam shaping optics within a beam line; having the ability to instantly verify by a qualitative means that each element is in its proper position as the beam shaper module is being aligned. There is a need to reduce these types of alignment techniques down to a level where even a newbie to optical alignment will be able to complete the task. Couple this alignment need with the fact that most laser system manufacturers ship their products worldwide and the introduction of a new set of variables including cultural and language barriers, makes this a top priority for manufacturers. Tools and methodologies for alignment of complex optical systems need to be able to cross these barriers to ensure the highest degree of up time and reduce the cost of maintenance on the production floor. Customers worldwide, who purchase production laser equipment, understand that the majority of costs to a manufacturing facility is spent on system maintenance and is typically the largest single controllable expenditure in a production plant. This desire to reduce costs is driving the trend these days towards predictive and proactive, not reactive maintenance of laser based optical beam delivery systems [10]. With proper diagnostic tools, laser system developers can develop proactive approaches to reduce system down time, safe guard operational performance and reduce premature or catastrophic optics failures. Obviously analytical data will provide quantifiable performance standards which are more precise than qualitative standards, but each have a role in determining overall optical system performance [10]. This paper will discuss the use of film and fluorescent mirror devices as diagnostic tools for beam shaper module alignment off line or in-situ. The paper will also provide an overview methodology showing how it is possible to reduce complex alignment directions into a simplified set of instructions for layman service engineers.

Understanding Internal Accountability in Nigeria’s Routine Immunization System: Perspectives From Government Officials at the National, State, and Local Levels

PubMed Central

Erchick, Daniel J.; George, Asha S.; Umeh, Chukwunonso; Wonodi, Chizoba

2017-01-01

Background: Routine immunization coverage in Nigeria has remained low, and studies have identified a lack of accountability as a barrier to high performance in the immunization system. Accountability lies at the heart of various health systems strengthening efforts recently launched in Nigeria, including those related to immunization. Our aim was to understand the views of health officials on the accountability challenges hindering immunization service delivery at various levels of government. Methods: A semi-structured questionnaire was used to interview immunization and primary healthcare (PHC) officials from national, state, local, and health facility levels in Niger State in north central Nigeria. Individuals were selected to represent a range of roles and responsibilities in the immunization system. The questionnaire explored concepts related to internal accountability using a framework that organizes accountability into three axes based upon how they drive change in the health system. Results: Respondents highlighted accountability challenges across multiple components of the immunization system, including vaccine availability, financing, logistics, human resources, and data management. A major focus was the lack of clear roles and responsibilities both within institutions and between levels of government. Delays in funding, especially at lower levels of government, disrupted service delivery. Supervision occurred less frequently than necessary, and the limited decision space of managers prevented problems from being resolved. Motivation was affected by the inability of officials to fulfill their responsibilities. Officials posited numerous suggestions to improve accountability, including clarifying roles and responsibilities, ensuring timely release of funding, and formalizing processes for supervision, problem solving, and data reporting. Conclusion: Weak accountability presents a significant barrier to performance of the routine immunization system and high immunization coverage in Nigeria. As one stakeholder in ensuring the performance of health systems, routine immunization officials reveal critical areas that need to be prioritized if emerging interventions to improve accountability in routine immunization are to have an effect. PMID:28812836

Assessing the Role of Dune Topography on a Fresh Water Lens of a Siliciclastic Barrier Along the Northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Anderson, C. P.; Carter, G. A.; Mooneyhan, D.

2013-12-01

Carlton P. Anderson, Gregory Carter, and David Mooneyhan University of Southern Mississippi Gulf Coast Geospatial Center Department of Geography and Geology Carlton.p.anderson@eagles.usm.edu The Mississippi-Alabama (MS-AL) barrier island chain consist of dynamic depositional landforms that constantly undergo changes in their evolutionary processes through changes in sea level, sediment supply, and weather events. These complex landscapes of the Northern Gulf of Mexico (NGOM) provide a chance to study their geomorphological progressions, which have been produced by sea level rise and fluvial processes throughout the Holocene. Studies on the freshwater lens of barriers have mainly concentrated on carbonate island settings with minimal focus to barriers with siliciclastic geology. The purpose of this study is to examine the relationship beach dune topography plays in the development and sustainability of the fresh water lens of Cat Island, Mississippi. Cat Island offers the opportunity to research a siliciclastic barrier along the NGOM where minimal anthropogenic activities have taken place. To determine the effect dune topography has on the fresh water lens, a transect of permanent water wells were used in conjunction with test wells at different sites throughout the north spit of the island, to establish the water table height above the ellipsoid (WGS 84), with vertical accuracies of 2 cm. Cross-sectional profiles of the dunes were also performed utilizing purposeful transects that intersected fresh water ponds in the dune-swale systems. These ponds provide water table elevations at the surface which were interpolated across the dunes for areas that lacked permanent well sites. To obtain survey-grade accuracies, a Trimble TSC3 receiver coupled with a R8 antennae RTK system were used. Salinity measurements were taken at test sites to determine the salt-to-freshwater interface. Results provide insights into how dune topography influences the fresh water lens of a siliciclastic barrier.

Towards self-correcting quantum memories

NASA Astrophysics Data System (ADS)

Michnicki, Kamil

This thesis presents a model of self-correcting quantum memories where quantum states are encoded using topological stabilizer codes and error correction is done using local measurements and local dynamics. Quantum noise poses a practical barrier to developing quantum memories. This thesis explores two types of models for suppressing noise. One model suppresses thermalizing noise energetically by engineering a Hamiltonian with a high energy barrier between code states. Thermalizing dynamics are modeled phenomenologically as a Markovian quantum master equation with only local generators. The second model suppresses stochastic noise with a cellular automaton that performs error correction using syndrome measurements and a local update rule. Several ways of visualizing and thinking about stabilizer codes are presented in order to design ones that have a high energy barrier: the non-local Ising model, the quasi-particle graph and the theory of welded stabilizer codes. I develop the theory of welded stabilizer codes and use it to construct a code with the highest known energy barrier in 3-d for spin Hamiltonians: the welded solid code. Although the welded solid code is not fully self correcting, it has some self correcting properties. It has an increased memory lifetime for an increased system size up to a temperature dependent maximum. One strategy for increasing the energy barrier is by mediating an interaction with an external system. I prove a no-go theorem for a class of Hamiltonians where the interaction terms are local, of bounded strength and commute with the stabilizer group. Under these conditions the energy barrier can only be increased by a multiplicative constant. I develop cellular automaton to do error correction on a state encoded using the toric code. The numerical evidence indicates that while there is no threshold, the model can extend the memory lifetime significantly. While of less theoretical importance, this could be practical for real implementations of quantum memories. Numerical evidence also suggests that the cellular automaton could function as a decoder with a soft threshold.

Virtual reality exergaming as adjunctive therapy in a sub-acute stroke rehabilitation setting: facilitators and barriers.

PubMed

Nguyen, Ai-Vi; Ong, Yau-Lok Austin; Luo, Cindy Xin; Thuraisingam, Thiviya; Rubino, Michael; Levin, Mindy F; Kaizer, Franceen; Archambault, Philippe S

2018-03-12

To identify the facilitators and barriers perceived by clinicians to using an Exergaming Room as adjunct to conventional therapy. Phenomenological qualitative study using an interpretive description methodology. Ten clinicians (four physical therapists, six occupational therapists) from the Stroke Program at the Jewish Rehabilitation Hospital (nine female, one male, age range 25-50 years old) who referred clients to the Exergaming Room. Ten to twenty minute semi-structured interviews were conducted with each clinician. Convenience sampling was used. A thematic analysis was performed on the data collected by grouping all the open codes into facilitators and barriers, and then categorized into levels, themes and subthemes. Facilitators and barriers were divided into three levels: organizational, individual and technological. Major facilitators at the organizational level were: institutional support; at the individual level: personal experience of referring clinician, presence of an expert clinician, and relevance of the Exergaming Room for stroke clients; and at the technological level: perceived ease of use of the exergames and possibility of providing additional therapy. Key barriers to successful implementation of the Exergaming Room at the organizational level were: scheduling difficulties and lack of staffing; at the individual level: client functional limitations; at the technological level: low precision in motion capture of the exergame systems. Multiple factors affect the implementation of new technology in rehabilitation settings. In order to successfully integrate exergame systems into practice, institutions are encouraged to take the identified factors (facilitators and barriers) into account. Implications for Rehabilitation Clinicians who have referred individuals with stroke to an "exergames" room over a 1-year period at a rehabilitation hospital have found the service to be highly relevant to their clients. The presence of an expert clinician, who evaluates the clients and builds an exergames activity program, was seen as an important facilitator by referring clinicians in the use of this service. An ideal Exergames Room should offer a wide variety of activities, including some that focus on motor, cognitive and/or communications abilities.

Patient centered care: A path to better health outcomes through engagement and activation.

PubMed

Miller, Kenneth L

2016-10-14

Patient Activation and Health confidence are constructs to assess patient engagement and are utilized to encourage patient engagement. A health care provider may increase patient engagement further by utilizing behavior change theories and models such as the Trans-Theoretical Model of Change (TTM), Self-Determination Theory (SDT) and Motivational Interviewing (MI) to realize effective and lasting health behavior change by placing accountability increasingly on the patient/caregiver to choose to make changes in their health behavior on their terms. Reducing or eliminating harmful behaviors such as smoking and/or beginning or increasing beneficial health behaviors such as diet modification or performance of an exercise program, patients realize improved outcomes and better health. The purpose of this article is to define health confidence as a measurement tool for patient engagement, use the TTM as a measure of the patient's readiness to change, use TTM, SDT and MI as interventional approaches to effect patient change of behavior encouraged by physical therapists and incorporate the ICF as a means of identifying barriers and facilitators and incorporate the bio-psychosocial model for patient-centered care to improve health behavior, health and patient outcomes. Patient-centered care requires involvement of the patient and/or their caregiver at the center of the plan. Use of the International Classification of Functioning, Disability and Health (ICF) to identify facilitators and barriers unique to the patient/caregiver offers another opportunity to successfully engage the patient by incorporating the patient's bio-psychosocial support system into care delivery and for sustainability. The ICF is a taxonomy and classification system that prompts clinicians to identify environmental factors (facilitators and barriers) that will influence the patient's ability to perform during therapy session and to sustain the interventions and employ suggestions outside of formal therapy sessions. Using the facilitators to encourage sustainable change and removing barriers, patients are more likely to realize positive health behavior change and in turn demonstrate improved outcomes and health as a result of physical therapy intervention.

How Accurate Are the Minnesota Density Functionals for Noncovalent Interactions, Isomerization Energies, Thermochemistry, and Barrier Heights Involving Molecules Composed of Main-Group Elements?

DOE PAGES

Mardirossian, Narbe; Head-Gordon, Martin

2016-08-18

The 14 Minnesota density functionals published between the years 2005 and early 2016 are benchmarked on a comprehensive database of 4986 data points (84 data sets) involving molecules composed of main-group elements. The database includes noncovalent interactions, isomerization energies, thermochemistry, and barrier heights, as well as equilibrium bond lengths and equilibrium binding energies of noncovalent dimers. Additionally, the sensitivity of the Minnesota density functionals to the choice of basis set and integration grid is explored for both noncovalent interactions and thermochemistry. By and large, the main strength of the hybrid Minnesota density functionals is that the best ones provide verymore » good performance for thermochemistry (e.g., M06-2X), barrier heights (e.g., M08-HX, M08-SO, MN15), and systems heavily characterized by self-interaction error (e.g., M06-2X, M08-HX, M08-SO, MN15), while the main weakness is that none of them are state-of-the-art for the full spectrum of noncovalent interactions and isomerization energies (although M06-2X is recommended from the 10 hybrid Minnesota functionals). Similarly, the main strength of the local Minnesota density functionals is that the best ones provide very good performance for thermochemistry (e.g., MN15-L), barrier heights (e.g., MN12-L), and systems heavily characterized by self-interaction error (e.g., MN12-L and MN15-L), while the main weakness is that none of them are state-of-the-art for the full spectrum of noncovalent interactions and isomerization energies (although M06-L is clearly the best from the four local Minnesota functionals). Finally, as an overall guide, M06-2X and MN15 are perhaps the most broadly useful hybrid Minnesota functionals, while M06-L and MN15-L are perhaps the most broadly useful local Minnesota functionals, although each has different strengths and weaknesses.« less

Design and analysis of the Collider SPXA/SPRA spool piece vacuum barrier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cruse, G.; Aksel, G.

1993-04-01

A design for the Collider SPXA/SPRA spool piece vacuum barrier was developed to meet a variety of thermal and structural performance requirements. Both composite and stainless steel alternatives were investigated using detailed finite-element analysis before selecting an optimized version of the ASST SPR spool vacuum barrier design. This design meets the structural requirements and will be able to meet the thermal performance requirements by using some newer thermal strapping configurations.

Isotopic effects in sub-barrier fusion of Si + Si systems

NASA Astrophysics Data System (ADS)

Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Esbensen, H.; Bourgin, D.; Čolović, P.; Corradi, L.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Szilner, S.; Urbani, M.; Zhang, G. L.

2018-04-01

Background: Recent measurements of fusion cross sections for the 28Si+28Si system revealed a rather unsystematic behavior; i.e., they drop faster near the barrier than at lower energies. This was tentatively attributed to the large oblate deformation of 28Si because coupled-channels (CC) calculations largely underestimate the 28Si+28Si cross sections at low energies, unless a weak imaginary potential is applied, probably simulating the deformation. 30Si has no permanent deformation and its low-energy excitations are of a vibrational nature. Previous measurements of this system reached only 4 mb, which is not sufficient to obtain information on effects that should show up at lower energies. Purpose: The aim of the present experiment was twofold: (i) to clarify the underlying fusion dynamics by measuring the symmetric case 30Si+30Si in an energy range from around the Coulomb barrier to deep sub-barrier energies, and (ii) to compare the results with the behavior of 28Si+28Si involving two deformed nuclei. Methods: 30Si beams from the XTU tandem accelerator of the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nucleare were used, bombarding thin metallic 30Si targets (50 μ g /cm2) enriched to 99.64 % in mass 30. An electrostatic beam deflector allowed the detection of fusion evaporation residues (ERs) at very forward angles, and angular distributions of ERs were measured. Results: The excitation function of 30Si+30Si was measured down to the level of a few microbarns. It has a regular shape, at variance with the unusual trend of 28Si+28Si . The extracted logarithmic derivative does not reach the LCS limit at low energies, so that no maximum of the S factor shows up. CC calculations were performed including the low-lying 2+ and 3- excitations. Conclusions: Using a Woods-Saxon potential the experimental cross sections at low energies are overpredicted, and this is a clear sign of hindrance, while the calculations performed with a M3Y + repulsion potential nicely fit the data at low energies, without the need of an imaginary potential. The comparison with the results for 28Si+28Si strengthens the explanation of the oblate shape of 28Si being the reason for the irregular behavior of that system.

LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS: LESSONS LEARNED ON DESIGN, CONTAMINANT TREATMENT, LONGEVITY, PERFORMANCE MONITORING AND COST-AN OVERVIEW

EPA Science Inventory

This presentation will provide an overview of permeable reactive barrier performance for field sites in the U.S. evaluated over the last 10 years by the U.S. Environmental Protection Agency's Office of Research and Development (EPA-ORD) in collaboration with other U.S. federal ag...

LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS: LESSONS LEARNED ON DESIGN, CONTAMINANT TREATMENT, LONGEVITY, PERFORMANCE MONITORING AND COST - AN OVERVIEW

EPA Science Inventory

An overview of permeable reactive barrier (PRB) performance for field sites in the U.S. was evaluated over the last 10 years by the U.S. Environmental Protection Agencys Office of Research and Development (EPA-ORD) in collaboration with other U.S. federal agencies, consulting co...

CAPSTONE REPORT ON THE APPLICATION, MONITORING, AND PERFORMANCE OF PERMEABLE REACTIVE BARRIERS FOR GROUND-WATER REMEDIATION: VOL. 1 PERFORMANCE EVALUATIONS AT TWO SITES

EPA Science Inventory

The purpose of this document is to provide detailed performance monitoring data on full-scale Permeable Reactive Barriers (PRBs) installed to treat contaminated ground water at two different sites. This report will fill a need for a readily available source of information for si...

Analysis of the diffraction effects for a multi-view autostereoscopic three-dimensional display system based on shutter parallax barriers with full resolution

NASA Astrophysics Data System (ADS)

Meng, Yang; Yu, Zhongyuan; Jia, Fangda; Zhang, Chunyu; Wang, Ye; Liu, Yumin; Ye, Han; Chen, Laurence Lujun

2017-10-01

A multi-view autostereoscopic three-dimensional (3D) system is built by using a 2D display screen and a customized parallax-barrier shutter (PBS) screen. The shutter screen is controlled dynamically by address driving matrix circuit and it is placed in front of the display screen at a certain location. The system could achieve densest viewpoints due to its specially optical and geometric design which is based on concept of "eye space". The resolution of 3D imaging is not reduced compared to 2D mode by using limited time division multiplexing technology. The diffraction effects may play an important role in 3D display imaging quality, especially when applied to small screen, such as iPhone screen etc. For small screen, diffraction effects may contribute crosstalk between binocular views, image brightness uniformity etc. Therefore, diffraction effects are analyzed and considered in a one-dimensional shutter screen model of the 3D display, in which the numerical simulation of light from display pixels on display screen through parallax barrier slits to each viewing zone in eye space, is performed. The simulation results provide guidance for criteria screen size over which the impact of diffraction effects are ignorable, and below which diffraction effects must be taken into account. Finally, the simulation results are compared to the corresponding experimental measurements and observation with discussion.

Off-Stream Watering Systems and Partial Barriers as a Strategy to Maximize Cattle Production and Minimize Time Spent in the Riparian Area

PubMed Central

Rawluk, Ashley A.; Crow, Gary; Legesse, Getahun; Veira, Douglas M.; Bullock, Paul R.; González, Luciano A.; Dubois, Melanie; Ominski, Kim H.

2014-01-01

Simple Summary The implementation of off-stream waterers (OSW) may reduce the amount of time cattle spend in riparian areas, thus minimizing impacts such as removal of vegetation, soil compaction, and deterioration in water quality. Furthermore, when used with natural barriers as a partial exclusion method, these management strategies may offer a cost-effective alternative to completely excluding cattle via streambank fencing. This study was conducted to determine the impact of OSW and barriers on animal performance and watering behavior. The presence of OSW had no significant effect on cow and calf weights averaged over the grazing season. Although the results were not consistent over the periods and locations, the data provided some indication of the efficacy of the natural barriers on deterring cattle from the riparian area. Cattle watered at the OSW when available, but they did not use the OSW exclusively. The observed inconsistency may, in part, be attributed to the environmental conditions present during this field trial. Abstract A study was conducted in 2009 at two locations in Manitoba (Killarney and Souris), Canada to determine the impact of off-stream waterers (OSW) with or without natural barriers on (i) amount of time cattle spent in the 10 m buffer created within the riparian area, referred to as the riparian polygon (RP), (ii) watering location (OSW or stream), and (iii) animal performance measured as weight gain. This study was divided into three 28-day periods over the grazing season. At each location, the pasture—which ranged from 21.0 ha to 39.2 ha in size—was divided into three treatments: no OSW nor barriers (1CONT), OSW with barriers along the stream bank to deter cattle from watering at the stream (2BARR), and OSW without barriers (3NOBARR). Cattle in 2BARR spent less time in the RP in Periods 1 (p = 0.0002), 2 (p = 0.1116), and 3 (p < 0.0001) at the Killarney site compared to cattle in 3NOBARR at the same site. Cattle in 2BARR at the Souris site spent more time in the RP in Period 1 (p < 0.0001) and less time in Period 2 (p = 0.0002) compared to cattle in 3NOBARR. Cattle did use the OSW, but not exclusively, as watering at the stream was still observed. The observed inconsistency in the effectiveness of the natural barriers on deterring cattle from the riparian area between periods and locations may be partly attributable to the environmental conditions present during this field trial as well as difference in pasture size and the ability of the established barriers to deter cattle from using the stream as a water source. Treatment had no significant effect (p > 0.05) on cow and calf weights averaged over the summer period. These results indicate that the presence of an OSW does not create significant differences in animal performance when used in extensive pasture scenarios such as those studied within the present study. Whereas the barriers did not consistently discourage watering at the stream, the results provide some indication of the efficacy of the OSW as well as the natural barriers on deterring cattle from the riparian area. PMID:26479006

Effect of Si in reactively sputtered Ti-Si-N films on structure and diffusion barrier performance

NASA Astrophysics Data System (ADS)

Sun, X.; Kolawa, E.; Im, S.; Garland, C.; Nicolet, M.-A.

Two ternary films about 100 nm thick, Ti34Si23N43 (b3) and Ti35Si13N52 (c3), are synthesized by reactively sputtering a Ti5Si3 or a Ti3Si target, respectively. The silicon-lean film (c3) has a columnar structure closely resembling that of TiN. As a diffusion barrier between a shallow Si n+p junction diode and a Cu overlayer, this material is effective up to 700 °C for 30 min annealing in vacuum, a performance similar to that for TiN. The silicon-rich (b3) film contains nanocrystals of TiN, randomly oriented and embedded in an amorphous matrix. A film of (b3) maintains the stability of the same diode structure up to 850 °C for 30 min in vacuum. This film (b3) is clearly superior to TiN or to (c3). Similar experiments performed with Al instead of Cu overlayers highlight the importance of the thermodynamic stability of a barrier layer and demonstrate convincingly that for stable barriers the microstructure is a parameter that directly determines the barrier performance.

Long-term Performance of Permeable Reactive Barriers Using Zero-valent Iron: An Evaluation at Two Sites

DTIC Science & Technology

2002-01-01

samples were placed in a glass reaction vessel and purged with CO2- scrubbed air. The samples were then acidified with hot, 5% perchloric acid and...extractable carbon. Total sulfur measurements were made with a UIC sulfur coulometer system. Iron samples were covered with V2O5 and combusted in the

ABLEPathPlanner library for Umbra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oppel III, Fred J; Xavier, Patrick G.; Gottlieb, Eric Joseph

Umbra contains a flexible, modular path planner that is used to simulate complex entity behaviors moving within 3D terrain environments that include buildings, barriers, roads, bridges, fences, and a variety of other terrain features (water, vegetation, slope, etc…). The path planning algorithm is a critical component required to execute these tactical behaviors to provide realistic entity movement and provide efficient system computing performance.

Ultra low power CMOS technology

NASA Technical Reports Server (NTRS)

Burr, J.; Peterson, A.

1991-01-01

This paper discusses the motivation, opportunities, and problems associated with implementing digital logic at very low voltages, including the challenge of making use of the available real estate in 3D multichip modules, energy requirements of very large neural networks, energy optimization metrics and their impact on system design, modeling problems, circuit design constraints, possible fabrication process modifications to improve performance, and barriers to practical implementation.

Investigating Student Resistance and Student Perceptions of Course Quality and Instructor Performance in a Flipped Information Systems Classroom

ERIC Educational Resources Information Center

Baker, Elizabeth White; Hill, Stephen

2017-01-01

The study focuses on the instructor as a stakeholder in implementing the flipped classroom learning approach and ways to lessen professor resistance to flipped classroom adoption. The barrier to professor adoption that concerns potentially lower student evaluations as a result of incorporating the new approach is of particular interest. The…

Screening based approach and dehydrogenation kinetics for MgH2: Guide to find suitable dopant using first-principles approach.

PubMed

Kumar, E Mathan; Rajkamal, A; Thapa, Ranjit

2017-11-14

First-principles based calculations are performed to investigate the dehydrogenation kinetics considering doping at various layers of MgH 2 (110) surface. Doping at first and second layer of MgH 2 (110) has a significant role in lowering the H 2 desorption (from surface) barrier energy, whereas the doping at third layer has no impact on the barrier energy. Molecular dynamics calculations are also performed to check the bonding strength, clusterization, and system stability. We study in details about the influence of doping on dehydrogenation, considering the screening factors such as formation enthalpy, bulk modulus, and gravimetric density. Screening based approach assist in finding Al and Sc as the best possible dopant in lowering of desorption temperature, while preserving similar gravimetric density and Bulk modulus as of pure MgH 2 system. The electron localization function plot and population analysis illustrate that the bond between Dopant-Hydrogen is mainly covalent, which weaken the Mg-Hydrogen bonds. Overall we observed that Al as dopant is suitable and surface doping can help in lowering the desorption temperature. So layer dependent doping studies can help to find the best possible reversible hydride based hydrogen storage materials.

Ultrasonic Detection of Delamination and Material Characterization of Thermal Barrier Coatings

NASA Astrophysics Data System (ADS)

Chen, Hung-Liang Roger; Zhang, Binwei; Alvin, Mary Anne; Lin, Yun

2012-12-01

This article describes ultrasonic nondestructive evaluation (NDE) to detect the changes of material properties and provide early warning of delamination in thermal barrier coating (TBC) systems. NDE tests were performed on single-crystal René N5 superalloy coupons that were coated with a commercially available MCrAlY bond coat and an air plasma sprayed 7% yttria-stabilized zirconia (YSZ) top coat deposited by Air Plasma Spray method, as well as Haynes 230 superalloy coupons coated with MCrA1Y bond coat, and an electron beam physical vapor deposit of 7% YSZ top coat. The TBC coupons were subjected to either cyclic or isothermal exposure for various lengths of time at temperatures ranging from 900 to 1100 °C. The ultrasonic measurements performed on the coupons had provided an early warning of delamination along the top coat/TGO interface before exposure time, when delamination occurred. The material's property (Young's modulus) of the top coat was estimated using the measured wave speeds. Finite element analysis (FEA) of the ultrasonic wave propagation was conducted on a simplified TBC system to verify experimental observations. The technique developed was also demonstrated on an as-manufactured turbine blade to estimate normalized top coat thickness measurements.

Barriers to initiating tuberculosis treatment in sub-Saharan Africa: a systematic review focused on children and youth

PubMed Central

Sullivan, Brittney J.; Esmaili, B. Emily; Cunningham, Coleen K.

2017-01-01

ABSTRACT Background: Tuberculosis (TB) is the deadliest infectious disease globally, with 10.4 million people infected and more than 1.8 million deaths in 2015. TB is a preventable, treatable, and curable disease, yet there are numerous barriers to initiating treatment. These barriers to treatment are exacerbated in low-resource settings and may be compounded by factors related to childhood. Objective: Timely initiation of tuberculosis (TB) treatment is critical to reducing disease transmission and improving patient outcomes. The aim of this paper is to describe patient- and system-level barriers to TB treatment initiation specifically for children and youth in sub-Saharan Africa through systematic review of the literature. Design: This review was conducted in October 2015 in accordance with preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Six databases were searched to identify studies where primary or secondary objectives were related to barriers to TB treatment initiation and which included children or youth 0–24 years of age. Results: A total of 1490 manuscripts met screening criteria; 152 met criteria for full-text review and 47 for analysis. Patient-level barriers included limited knowledge, attitudes and beliefs regarding TB, and economic burdens. System-level barriers included centralization of services, health system delays, and geographical access to healthcare. Of the 47 studies included, 7 evaluated cost, 19 health-seeking behaviors, and 29 health system infrastructure. Only 4 studies primarily assessed pediatric cohorts yet all 47 studies were inclusive of children. Conclusions: Recognizing and removing barriers to treatment initiation for pediatric TB in sub-Saharan Africa are critical. Both patient- and system-level barriers must be better researched in order to improve patient outcomes. PMID:28598771

Performance of temporary concrete traffic barriers during the widening of I-95.

DOT National Transportation Integrated Search

1982-01-01

This research effort was initiated at the request of officials of the Virginia Department of Highways and Transportation to obtain information on the performance of the precast concrete traffic barrier (PCTB) when exposed to heavy vehicles. The PCTB ...

Thermal Analysis of a Carbon Fiber Rope Barrier for Use in the Reusable Solid Rocket Motor Nozzle Joint-2

NASA Technical Reports Server (NTRS)

Clayton, J. Louie

2002-01-01

This study provides development and verification of analysis methods used to assess performance of a carbon fiber rope (CFR) thermal barrier system that is currently being qualified for use in Reusable Solid Rocket Motor (RSRM) nozzle joint-2. Modeled geometry for flow calculations considers the joint to be vented with the porous CFR barriers placed in the 'open' assembly gap. Model development is based on a 1-D volume filling approach where flow resistances (assembly gap and CFRs) are defined by serially connected internal flow and the porous media 'Darcy' relationships. Combustion gas flow rates are computed using the volume filling code by assuming a lumped distribution total joint fill volume on a per linear circumferential inch basis. Gas compressibility, friction and heat transfer are included in the modeling. Gas-to-wall heat transfer is simulated by concurrent solution of the compressible flow equations and a large thermal 2-D finite element (FE) conduction grid. The derived numerical technique loosely couples the FE conduction matrix with the compressible gas flow equations. Free constants that appear in the governing equations are calibrated by parametric model comparison to hot fire subscale test results. The calibrated model is then used to make full-scale motor predictions using RSRM aft dome environments. Model results indicate that CFR thermal barrier systems will provide a thermally benign and controlled pressurization environment for the RSRM nozzle joint-2 primary seal activation.

Thermal Analysis of a Carbon Fiber Rope Barrier for Use in the Reusable Solid Rocket Motor Nozzle Joint-2

NASA Technical Reports Server (NTRS)

Clayton, J. Louie; Phelps, Lisa (Technical Monitor)

2001-01-01

This study provides for development and verification of analysis methods used to assess performance of a carbon fiber rope (CFR) thermal barrier system that is currently being qualified for use in Reusable Solid Rocket Motor (RSRM) nozzle joint-2. Modeled geometry for flow calculations considers the joint to be vented with the porous CFR barriers placed in the "open' assembly gap. Model development is based on a 1-D volume filling approach where flow resistances (assembly gap and CFRs) are defined by serially connected internal flow and the porous media "Darcy" relationships. Combustion gas flow rates are computed using the volume filling code by assuming a lumped distribution total joint fill volume on a per linear circumferential inch basis. Gas compressibility, friction and heat transfer are included in the modeling. Gas-to-wall heat transfer is simulated by concurrent solution of the compressible flow equations and a large thermal 2-D finite element (FE) conduction grid. The derived numerical technique loosely couples the FE conduction matrix with the compressible gas flow equations, Free constants that appear in the governing equations are calibrated by parametric model comparison to hot fire subscale test results. The calibrated model is then used to make full-scale motor predictions using RSRM aft dome environments. Model results indicate that CFR thermal barrier systems will provide a thermally benign and controlled pressurization environment for the RSRM nozzle joint-2 primary seal activation.

Factors Associated With Utilization of Cardiac Rehabilitation Among Patients With Ischemic Heart Disease in the Veterans Health Administration: A QUALITATIVE STUDY.

PubMed

Schopfer, David W; Priano, Susan; Allsup, Kelly; Helfrich, Christian D; Ho, P Michael; Rumsfeld, John S; Forman, Daniel E; Whooley, Mary A

2016-01-01

Cardiac rehabilitation (CR) programs reduce morbidity and mortality in patients with ischemic heart disease but are vastly underutilized in the United States, including the Veterans Health Administration (VA) Healthcare System. Numerous barriers affecting utilization have been identified in other health care systems, but the specific factors affecting Veterans are unknown. We sought to identify barriers and facilitators associated with utilization of CR in VA facilities. We performed a qualitative study of 56 VA patients, providers, and CR program managers at 30 VA facilities across the United States. We conducted semistructured interviews with key informants to explore their attitudes and knowledge toward CR. Interviews were conducted until thematic saturation occurred. Analyses using grounded theory to identify key themes were conducted using the qualitative data analysis package ATLAS.ti. We identified 6 themes as barriers and 5 as facilitators. The most common barriers to participation in CR were patient transportation issues (68%), lack of patient willingness to participate (41%), and no access to a nearby VA hospital with a CR program (30%). The most common facilitators were involvement of a dedicated provider or "clinical champion" (50%), provider knowledge of or experience with CR (48%), and patient desire for additional medical support (32%). Our findings suggest that addressing access issues and educating and activating providers on CR may increase utilization of CR programs. Targeting these specific factors may improve utilization of CR programs.

[Neurological disorders and the blood-brain barrier. Strategies and limitations for drug delivery to the brain].

PubMed

Domínguez, Alazne; Álvarez, Antonia; Suárez-Merino, Blanca; Goñi-de-Cerio, Felipe

2014-03-01

The incidence in the central nervous system diseases has increased with a growing elderly population. Unfortunately, conventional treatments used to treat the mentioned diseases are frequently ineffective due to the presence of the blood brain barrier. To illustrate the blood-brain barrier properties that limit drug transport into the brain and the main strategies employed to treat neurologic disorders. The blood-brain barrier is mainly composed of a specialized microvascular endothelium and of glial cells. It constitutes a valuable tool to separate the central nervous system from the rest of the body. Nevertheless, it also represents an obstacle to the delivery of therapeutic drugs to the brain. To be effective, drugs must reach their target in the brain. On one hand, therapeutic agents could be designed to be able to cross the blood brain barrier. On the other hand, drug delivery systems could be employed to facilitate the therapeutic agents' entry into the central nervous system. In vivo models of neurological diseases, in addition to in vitro models of the blood brain barrier, have been widely employed for the evaluation of drugs utilized to treat central nervous system diseases.

YIP Formal Synthesis of Software-Based Control Protocols for Fractionated,Composable Autonomous Systems

DTIC Science & Technology

2016-07-08

Systems Using Automata Theory and Barrier Certifi- cates We developed a sound but incomplete method for the computational verification of specifications...method merges ideas from automata -based model checking with those from control theory including so-called barrier certificates and optimization-based... Automata theory meets barrier certificates: Temporal logic verification of nonlinear systems,” IEEE Transactions on Automatic Control, 2015. [J2] R

Evaluating the long-term hydrology of an evapotranspiration-capillary barrier with a 1000 year design life: HYDROLOGY OF A 1000 YEAR ETC BARRIER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Z. Fred

A surface barrier (or cover) is a commonly used technology for subsurface remediation. A key function of the barrier is to reduce or eliminate the movement of meteoric precipitation into the underlying waste zone, where it could mobilize and transport contaminants. Surface barriers are expected to perform for centuries to millennia, yet there are very few examples of performance for periods longer than a decade. The Prototype Hanford Barrier was constructed in 1994 over an existing waste site to demonstrate its long-term performance for a design period of 1000 years. This barrier is a field-scale evapotranspiration-capillary (ETC) barrier. In thismore » design, the storage layer consists of 2-m-thick silt loam. The 19-year monitoring results show that the store-and-release mechanism for the ETC barrier worked efficiently as the storage layer was recharged in the winter season (November to March) and the stored water was released to the atmosphere in the summer season (April to October) via soil evaporation and plant transpiration. The capillary break functioned normally in improving the storage capacity and minimizing drainage. The maximum drainage observed through the ET barrier at any of the monitoring stations was only 0.178 mm yr-1 (under an enhanced precipitation condition), which is less than the design criterion. A very small amount (2.0 mm yr-1 on average) of runoff was observed during the 19-year monitoring period. The observed storage capacity of the storage layer was considerably (39%) larger than the estimated value based on the method of equilibrium of water pressure. After a controlled fire in 2008, the newly grown vegetation (primarily shallow-rooted grasses) could still release the stored water and summer precipitation to the atmosphere via transpiration. The findings are useful for predicting water storage and ET under different precipitation conditions and for the design of future barriers.« less

Multimodal sensing strategies for detecting transparent barriers indoors from a mobile platform

NASA Astrophysics Data System (ADS)

Acevedo, Isaiah; Kleine, R. Kaleb; Kraus, Dustan; Mascareñas, David

2015-04-01

There is currently an interest in developing mobile sensing platforms that fly indoors. The primary goal for these platforms is to be able to successfully navigate a building under various lighting and environmental conditions. There are numerous research challenges associated with this goal, one of which is the platform's ability to detect and identify the presence of transparent barriers. Transparent barriers could include windows, glass partitions, or skylights. For example, in order to successfully navigate inside of a structure, these platforms will need to sense if a space contains a transparent barrier and whether or not this space can be traversed. This project's focus has been developing a multimodal sensing system that can successfully identify such transparent barriers under various lighting conditions while aboard a mobile platform. Along with detecting transparent barriers, this sensing platform is capable of distinguishing between reflective, opaque, and transparent barriers. It will be critical for this system to be able to identify transparent barriers in real-time in order for the navigation system to maneuver accordingly. The properties associated with the interaction between various frequencies of light and transparent materials were one of the techniques leveraged to solve this problem.

Ground-source heat pump case studies and utility programs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lienau, P.J.; Boyd, T.L.; Rogers, R.L.

1995-04-01

Ground-source heat pump systems are one of the promising new energy technologies that has shown rapid increase in usage over the past ten years in the United States. These systems offer substantial benefits to consumers and utilities in energy (kWh) and demand (kW) savings. The purpose of this study was to determine what existing monitored data was available mainly from electric utilities on heat pump performance, energy savings and demand reduction for residential, school and commercial building applications. In order to verify the performance, information was collected for 253 case studies from mainly utilities throughout the United States. The casemore » studies were compiled into a database. The database was organized into general information, system information, ground system information, system performance, and additional information. Information was developed on the status of demand-side management of ground-source heat pump programs for about 60 electric utility and rural electric cooperatives on marketing, incentive programs, barriers to market penetration, number units installed in service area, and benefits.« less

Reactive Membrane Barriers for Containment of Subsurface Contamination

DOE Office of Scientific and Technical Information (OSTI.GOV)

William A. Arnold; Edward L. Cussler

2007-02-26

The overall goal of this project was to develop reactive membrane barriers--a new and flexible technique to contain and stabilize subsurface contaminants. Polymer membranes will leak once a contaminant is able to diffuse through the membrane. By incorporating a reactive material in the polymer, however, the contaminant is degraded or immobilized within the membrane. These processes increase the time for contaminants to breakthrough the barrier (i.e. the lag time) and can dramatically extend barrier lifetimes. In this work, reactive barrier membranes containing zero-valent iron (Fe{sup 0}) or crystalline silicotitanate (CST) were developed to prevent the migration of chlorinated solvents andmore » cesium-137, respectively. These studies were complemented by the development of models quantifying the leakage/kill time of reactive membranes and describing the behavior of products produced via the reactions within the membranes. First, poly(vinyl alcohol) (PVA) membranes containing Fe{sup 0} and CST were prepared and tested. Although PVA is not useful in practical applications, it allows experiments to be performed rapidly and the results to be compared to theory. For copper ions (Cu{sup 2+}) and carbon tetrachloride, the barrier was effective, increasing the time to breakthrough over 300 times. Even better performance was expected, and the percentage of the iron used in the reaction with the contaminants was determined. For cesium, the CST laden membranes increased lag times more than 30 times, and performed better than theoretical predictions. A modified theory was developed for ion exchangers in reactive membranes to explain this result. With the PVA membranes, the effect of a groundwater matrix on barrier performance was tested. Using Hanford groundwater, the performance of Fe{sup 0} barriers decreased compared to solutions containing a pH buffer and high levels of chloride (both of which promote iron reactivity). For the CST bearing membrane, performance improved by a factor of three when groundwater was used in place of deionized water. The performance of high density polyethylene (HDPE) membranes containing Fe{sup 0} was then evaluating using carbon tetrachloride as the target contaminant. Only with a hydrophilic additive (glycerol), was the iron able to extend lag times. Lag times were increased by a factor of 15, but only 2-3% of the iron was used, likely due to formation of oxide precipitates on the iron surface, which slowed the reaction. With thicker membranes and lower carbon tetrachloride concentrations, it is expected that performance will improve. Previous models for reactive membranes were also extended. The lag time is a measurement of when the barrier is breached, but contaminants do slowly leak through prior to the lag time. Thus, two parameters, the leakage and the kill time, were developed to determine when a certain amount of pollutant has escaped (the kill time) or when a given exposure (concentration x time) occurs (the leakage). Finally, a model was developed to explain the behavior of mobile reaction products in reactive barrier membranes. Although the goal of the technology is to avoid such products, it is important to be able to predict how these products will behave. Interestingly, calculations show that for any mobile reaction products, one half of the mass will diffuse into the containment area and one half will escape, assuming that the volumes of the containment area and the surrounding environment are much larger than the barrier membrane. These parameters/models will aid in the effective design of barrier membranes.« less

Barriers to healthcare for transgender individuals.

PubMed

Safer, Joshua D; Coleman, Eli; Feldman, Jamie; Garofalo, Robert; Hembree, Wylie; Radix, Asa; Sevelius, Jae

2016-04-01

Transgender persons suffer significant health disparities and may require medical intervention as part of their care. The purpose of this manuscript is to briefly review the literature characterizing barriers to healthcare for transgender individuals and to propose research priorities to understand mechanisms of those barriers and interventions to overcome them. Current research emphasizes sexual minorities' self-report of barriers, rather than using direct methods. The biggest barrier to healthcare reported by transgender individuals is lack of access because of lack of providers who are sufficiently knowledgeable on the topic. Other barriers include: financial barriers, discrimination, lack of cultural competence by providers, health systems barriers, and socioeconomic barriers. National research priorities should include rigorous determination of the capacity of the US healthcare system to provide adequate care for transgender individuals. Studies should determine knowledge and biases of the medical workforce across the spectrum of medical training with regard to transgender medical care; adequacy of sufficient providers for the care required, larger social structural barriers, and status of a framework to pay for appropriate care. As well, studies should propose and validate potential solutions to address identified gaps.

Proxy records of Holocene storm events in coastal barrier systems: Storm-wave induced markers

NASA Astrophysics Data System (ADS)

Goslin, Jérôme; Clemmensen, Lars B.

2017-10-01

Extreme storm events in the coastal zone are one of the main forcing agents of short-term coastal system behavior. As such, storms represent a major threat to human activities concentrated along the coasts worldwide. In order to better understand the frequency of extreme events like storms, climate science must rely on longer-time records than the century-scale records of instrumental weather data. Proxy records of storm-wave or storm-wind induced activity in coastal barrier systems deposits have been widely used worldwide in recent years to document past storm events during the last millennia. This review provides a detailed state-of-the-art compilation of the proxies available from coastal barrier systems to reconstruct Holocene storm chronologies (paleotempestology). The present paper aims (I) to describe the erosional and depositional processes caused by storm-wave action in barrier and back-barrier systems (i.e. beach ridges, storm scarps and washover deposits), (ii) to understand how storm records can be extracted from barrier and back-barrier sedimentary bodies using stratigraphical, sedimentological, micro-paleontological and geochemical proxies and (iii) to show how to obtain chronological control on past storm events recorded in the sedimentary successions. The challenges that paleotempestology studies still face in the reconstruction of representative and reliable storm-chronologies using these various proxies are discussed, and future research prospects are outlined.

36 CFR § 1192.109 - Between-car barriers.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 36 Parks, Forests, and Public Property 3 2013-07-01 2012-07-01 true Between-car barriers. § 1192... Commuter Rail Cars and Systems § 1192.109 Between-car barriers. Where vehicles operate in a high-platform, level-boarding mode, and where between-car bellows are not provided, devices or systems shall be...

Exploring barriers to primary care for migrants in Greece in times of austerity: Perspectives of service providers.

PubMed

Papadakaki, Maria; Lionis, Christos; Saridaki, Aristoula; Dowrick, Christopher; de Brún, Tomas; O'Reilly-de Brún, Mary; O'Donnell, Catherine A; Burns, Nicola; van Weel-Baumgarten, Evelyn; van den Muijsenbergh, Maria; Spiegel, Wolfgang; MacFarlane, Anne

2017-12-01

Migration in Europe is increasing at an unprecedented rate. There is an urgent need to develop 'migrant-sensitive healthcare systems'. However, there are many barriers to healthcare for migrants. Despite Greece's recent, significant experiences of inward migration during a period of economic austerity, little is known about Greek primary care service providers' experiences of delivering care to migrants. To identify service providers' views on the barriers to migrant healthcare. Qualitative study involving six participatory learning and action (PLA) focus group sessions with nine service providers. Data generation was informed by normalization process theory (NPT). Thematic analysis was applied to identify barriers to efficient migrant healthcare. Three main provider and system-related barriers emerged: (a) emphasis on major challenges in healthcare provision, (b) low perceived control and effectiveness to support migrant healthcare, and (c) attention to impoverished local population. The study identified major provider and system-related barriers in the provision of primary healthcare to migrants. It is important for the healthcare system in Greece to provide appropriate supports for communication in cross-cultural consultations for its diversifying population.

Transfer couplings and hindrance far below the barrier for 40 Ca + 96 Zr

DOE PAGES

Stefanini, A. M.; Montagnoli, G.; Esbensen, H.; ...

2015-01-29

The sub-barrier fusion excitation function of 40Ca + 96Zr has been measured down to cross sections ≃2.4µb, i.e. two orders of magnitude smaller than obtained in the previous experiment, where the sub-barrier fusion of this system was found to be greatly enhanced with respect to 40Ca + 90Zr, and the need of coupling to transfer channels was suggested. The purpose of this work was to investigate the behavior of 40Ca + 96Zr fusion far below the barrier. The smooth trend of the excitation function has been found to continue, and the logarithmic slope increases very slowly. No indication of hindrancemore » shows up, and a comparison with 48Ca + 96Zr is very useful in this respect. A new CC analysis of the complete excitation function has been performed, including explicitly one- and two-nucleon Q >0 transfer channels. Such transfer couplings bring significant cross section enhancements, even at the level of a few µb. Locating the hindrance threshold, if any, in 40Ca + 96Zr would require challenging measurements of cross sections in the sub-µb range.« less

What helps or hinders the transformation from a major tertiary center to a major trauma center? Identifying barriers and enablers using the Theoretical Domains Framework.

PubMed

Roberts, Neil; Lorencatto, Fabiana; Manson, Joanna; Brundage, Susan I; Jansen, Jan O

2016-03-12

Major Trauma Centers (MTCs), as part of a trauma system, improve survival and functional outcomes from injury. Developing such centers from current teaching hospitals is likely to generate diverse beliefs amongst staff. These may act as barriers or enablers. Prior identification of these may make the service development process more efficient. The importance of applying theory to systematically identify barriers and enablers to changing clinical practice in emergency medicine has been emphasized. This study systematically explored theory-based barriers and enablers towards implementing the transformation of a tertiary hospital into a MTC. Our goal was to demonstrate the use of a replicable method to identify targets that could be addressed to achieve a successful transformation from an organization evolved to provide a particular type of clinical care into a clinical system with different demands, requirements and expectations. The Theoretical Domains Framework (TDF) is a tool designed to elicit and analyze beliefs affecting behavior. Semi-structured interviews based around the TDF were conducted in a major tertiary hospital in Scotland due to become a MTC with a purposive sample of major stakeholders including clinicians and nurses from specialties involved in trauma care, clinical managers and administration. Belief statements were identified through qualitative analysis, and assessed for importance according to prevalence, discordance and evidence base. 1728 utterances were recorded and coded into 91 belief statements. 58 were classified as important barriers/enablers. There were major concerns about resource demands, with optimism conditional on these being met. Distracting priorities abound within the Emergency Department. Better communication is needed. Staff motivation is high and they should be engaged in skills development and developing performance improvement processes. This study presents a systematic and replicable method of identifying theory-based barriers and enablers towards complex service development. It identifies multiple barriers/enablers that may serve as a basis for developing an implementation intervention to enhance the development of MTCs. This method can be used to address similar challenges in developing specialist centers or implementing clinical practice change in emergency care across both developing and developed countries.

Effect of hygric and thermal properties of connecting layers on the performance of interior thermal insulation systems

NASA Astrophysics Data System (ADS)

Kočí, Václav; Jerman, Miloš; Fiala, Lukáš; Černý, Robert

2017-11-01

Interior thermal insulation systems represent often the only way of thermal protection, especially when historical buildings are taken into account. Since these systems face distrust due to frequent moisture failures, alternative solutions substituting the common water vapor barrier are being sought. In this paper, an assessment of hygrothermal performance of interior thermal insulation systems with purposely developed connecting layers is presented. Two types of mineral wools are connected to a sandstone masonry using two different connecting materials. The hygrothermal performance of the wall is obtained as a result of computational modelling with experimentally determined material parameters. Dynamic boundary conditions in the form of climatic data for Prague are used. The results indicate that the combination of permeable thermal insulation materials with investigated connecting layers have a positive influence on hygrothermal performance of the system as the moisture content is kept on very low level during a reference year. On the other hand, an increased attention should be paid to the protection of the masonry against excessive weather straining due to the absence of exterior thermal insulation.

Stakeholders identify similar barriers but different strategies to facilitate return-to-work: A vignette of a worker with an upper extremity condition.

PubMed

Peters, Susan E; Truong, Anthony P; Johnston, Venerina

2018-01-01

Stakeholders involved in the return-to-work (RTW) process have different roles and qualificationsOBJECTIVE:To explore the perspectives of Australian stakeholders of the RTW barriers and strategies for a worker with an upper extremity condition and a complex workers' compensation case. Using a case vignette, stakeholders were asked to identify barriers and recommend strategies to facilitate RTW. Content analysis was performed on the open-ended responses. The responses were categorised into RTW barriers and strategies using the biopsychosocial model. Pearson's Chi Square and ANOVA were performed to establish group differences. 621 participants (488 healthcare providers (HCPs), 62 employers, 55 insurers and 16 lawyers) identified 36 barriers (31 modifiable): 4 demographic; 8 biological; 15 psychological and 9 social barriers. 484 participants reported 16 RTW strategies: 4 biological; 6 psychological and 6 social strategies. 'Work relationship stressors' (83.4%) and 'Personal relationship stressors' (64.7%) were the most frequently nominated barriers. HCPs most frequently nominated 'Pain management' (49.6%), while employers, insurers and lawyers nominated 'RTW planning/Suitable duties programs' (40.5%; 42.9%; 80%). Stakeholders perceived similar barriers for RTW but recommended different strategies. Stakeholders appeared to be more proficient in identifying barriers than recommending strategies. Future research should focus on tools to both identify RTW barriers and direct intervention.

Structure and Barrier Properties of Multinanolayered Biodegradable PLA/PBSA Films: Confinement Effect via Forced Assembly Coextrusion.

PubMed

Messin, Tiphaine; Follain, Nadège; Guinault, Alain; Sollogoub, Cyrille; Gaucher, Valérie; Delpouve, Nicolas; Marais, Stéphane

2017-08-30

Multilayer coextrusion processing was applied to produce 2049-layer film of poly(butylene succinate-co-butylene adipate) (PBSA) confined against poly(lactic acid) (PLA) using forced assembly, where the PBSA layer thickness was about 60 nm. This unique technology allowed to process semicrystalline PBSA as confined polymer and amorphous PLA as confining polymer in a continuous manner. The continuity of PBSA layers within the 80/20 wt % PLA/PBSA layered films was clearly evidenced by atomic force microscopy (AFM). Similar thermal events to the reference films were revealed by thermal studies; indicating no diffusion of polymers during the melt-processing. Mechanical properties were measured for the multilayer film and the obtained results were those expected considering the fraction of each polymer, revealing the absence of delamination in the PLA/PBSA multinanolayer film. The confinement effect induced by PLA led to a slight orientation of the crystals, an increase of the rigid amorphous fraction (RAF) in PBSA with a densification of this fraction without changing film crystallinity. These structural changes allowed to strongly improve the water vapor and gas barrier properties of the PBSA layer into the multilayer film up to two decades in the case of CO 2 gas. By confining the PBSA structure in very thin and continuous layers, it was then possible to improve the barrier performances of a biodegradable system and the resulting barrier properties were successfully correlated to the effect of confinement on the microstructure and the chain segment mobility of the amorphous phase. Such investigation on these multinanolayers of PLA/PBSA with the aim of evidencing relationships between microstructure implying RAF and barrier performances has never been performed yet. Besides, gas and water permeation results have shown that the barrier improvement obtained from the multilayer was mainly due to the reduction of solubility linked to the reduction of the free volume while the tortuosity effect, as usually expected, was not really observed. This work brings new insights in the field of physicochemical behaviors of new multilayer films made of biodegradable polyesters but also in interfacial processes due to the confinement effect induced in these multinanolayer structures obtained by the forced assembly coextrusion. This original coextrusion process was a very advantageous technique to produce eco-friendly materials with functional properties without the help of tie layer, additives, solvents, surface treatments, or inorganic fillers.

Simulation and optimization of deep violet InGaN double quantum well laser

NASA Astrophysics Data System (ADS)

Alahyarizadeh, Gh.; Ghazai, A. J.; Rahmani, R.; Mahmodi, H.; Hassan, Z.

2012-03-01

The performance characteristics of a deep violet InGaN double quantum well laser diode (LD) such as threshold current ( Ith), external differential quantum efficiency (DQE) and output power have been investigated using the Integrated System Engineering Technical Computer Aided Design (ISE-TCAD) software. As well as its operating parameters such as internal quantum efficiency ( ηi), internal loss ( αi) and transparency threshold current density ( J0) have been studied. Since, we are interested to investigate the mentioned characteristics and parameters independent of well and barrier thickness, therefore to reach a desired output wavelength, the indium mole fraction of wells and barriers has been varied consequently. The indium mole fractions of well and barrier layers have been considered 0.08 and 0.0, respectively. Some important parameters such as Al mole fraction of the electronic blocking layer (EBL) and cavity length which affect performance characteristics were also investigated. The optimum values of the Al mole fraction and cavity length in this study are 0.15 and 400 μm, respectively. The lowest threshold current, the highest DQE and output power which obtained at the emission wavelength of 391.5 nm are 43.199 mA, 44.99% and 10.334 mW, respectively.

Evaluation of the in-service safety performance of safety-shape and vertical concrete barriers.

DOT National Transportation Integrated Search

2011-12-16

Roadside concrete barriers have been widely used to protect errant motorists from hitting : roadside hazards or obstacles. Two concrete barrier profiles, vertical and safety-shape, have been used : for this purpose. The safety-shape profile has been ...

Investigation of novel acoustic barrier concepts phase I: concept development and preliminary evaluation

DOT National Transportation Integrated Search

2003-06-01

In a previous research project [SQDH 2002-3; "Study of the Performance of Acoustic Barriers for Indiana Toll Roads,"] the influence of : environmental factors and of advanced sound barrier concepts was investigated. The presence of temperature gradie...

Collaborative Systems Thinking: A Response to the Problems Faced by Systems Engineering's 'Middle Tier'

NASA Technical Reports Server (NTRS)

Phfarr, Barbara B.; So, Maria M.; Lamb, Caroline Twomey; Rhodes, Donna H.

2009-01-01

Experienced systems engineers are adept at more than implementing systems engineering processes: they utilize systems thinking to solve complex engineering problems. Within the space industry demographics and economic pressures are reducing the number of experienced systems engineers that will be available in the future. Collaborative systems thinking within systems engineering teams is proposed as a way to integrate systems engineers of various experience levels to handle complex systems engineering challenges. This paper uses the GOES-R Program Systems Engineering team to illustrate the enablers and barriers to team level systems thinking and to identify ways in which performance could be improved. Ways NASA could expand its engineering training to promote team-level systems thinking are proposed.

Microbial barrier assessment of Tyvek stopper packaging for rubber closures.

PubMed

Moldenhauer, J E; Bass, S A; Kupinski, M J; Walters, M L; Rubio, S L

1996-01-01

Two types of Tyvek and high density polyethylene or polypropylene packaging used for sterilization of rubber closures were evaluated for Microbial Barrier properties. The packaging evaluated was "Ready to Sterilize" (1) stoppers and a second test package (Test 2) which was designated as appropriate for a clean room, filled with washed and siliconized stoppers and then heat sealed. Each type of packaging was subjected to three different sterilization temperatures (125 degrees C, 128 degrees C and 131 degrees C) in a production sterilizer (15-18 psi). Following sterilization, a microbial barrier assessment was performed, using Bacillus subtilis niger (ATCC 9372), to determine whether the packaging could maintain a sterile barrier following sterilization. Results of the testing indicated that a microbial barrier was maintained for products in "Ready to Sterilize" packages at 125 degrees C and 128 degrees C. For products sterilized in the Test 2 container a microbial barrier could not be maintained at 128 degrees C, and no further testing was performed. Following sterilization at 131 degrees C physical defects were noted for the "Ready to Sterilize" bag and a microbial barrier could not be maintained.

Physician attitude toward depression care interventions: Implications for implementation of quality improvement initiatives

PubMed Central

Henke, Rachel Mosher; Chou, Ann F; Chanin, Johann C; Zides, Amanda B; Scholle, Sarah Hudson

2008-01-01

Background Few individuals with depression treated in the primary care setting receive care consistent with clinical treatment guidelines. Interventions based on the chronic care model (CCM) have been promoted to address barriers and improve the quality of care. A current understanding of barriers to depression care and an awareness of whether physicians believe interventions effectively address those barriers is needed to enhance the success of future implementation. Methods We conducted semi-structured interviews with 23 primary care physicians across the US regarding their experience treating patients with depression, barriers to care, and commonly promoted CCM-based interventions. Themes were identified from interview transcripts using a grounded theory approach. Results Six barriers emerged from the interviews: difficulty diagnosing depression, patient resistance, fragmented mental health system, insurance coverage, lack of expertise, and competing demands and other responsibilities as a primary care provider. A number of interventions were seen as helpful in addressing these barriers – including care managers, mental health integration, and education – while others received mixed reviews. Mental health consultation models received the least endorsement. Two systems-related barriers, the fragmented mental health system and insurance coverage limitations, appeared incompletely addressed by the interventions. Conclusion CCM-based interventions, which include care managers, mental health integration, and patient education, are most likely to be implemented successfully because they effectively address several important barriers to care and are endorsed by physicians. Practices considering the adoption of interventions that received less support should educate physicians about the benefit of the interventions and attend to physician concerns prior to implementation. A focus on interventions that address systems-related barriers is needed to overcome all barriers to care. PMID:18826646

Effects of deposition temperature on the electrical properties of Ti/SiC Schottky barrier diodes

NASA Astrophysics Data System (ADS)

Oder, Tom N.; Kundeti, Krishna C.; Borucki, Nicholas; Isukapati, Sundar B.

2017-12-01

Ti Schottky contacts were deposited on n-type 4H-SiC at different temperatures ranging from 28 oC to 900 oC using a magnetron sputtering deposition system to fabricate Schottky barrier diodes. Post deposition annealing at 500 oC for up to 60 hours in vacuum was carried to further improve the contact properties. Optimum barrier height of 1.13 eV and ideality factor of 1.04 was obtained in contacts deposited at 200 oC and annealed for 60 hours. Under a reverse voltage bias of 400 V, the average leakage current on these set of diodes was 6.6 x 10-8 A. Based on the x-ray diffraction analysis, TiC, Ti5Si3 and Ti3SiC2 were formed at the Ti/SiC interface. These results could be beneficial to improving the performance of 4H-SiC Schottky diodes for high power and high temperature applications.

The AAS Working Group on Accessibility and Disability (WGAD): progress, current projects, and prospects for making astronomy accessible to all

NASA Astrophysics Data System (ADS)

Aarnio, Alicia; Diaz-Merced, Wanda; Monkiewicz, Jacqueline; Knierman, Karen; AAS WGAD

2018-01-01

Representation of astronomers with disabilities is low at the earliest career stages and losses compound with career stage thereafter; single-digit and lower percentage representation statistics are in large part due to systemic barriers to access and failure to accommodate the needs of users of a wide range of abilities. In this presentation, we discuss the barriers currently inhibiting broad access to astronomical publications, databases, and conferences. The WGAD was formed in January of 2016 to work toward removal of these barriers to make our field inclusive of astronomers with disabilities at all career stages. We have productively engaged with publishers and accessibility audits have been performed. Database accessibility evaluation is underway, and we are working with the AAS and other professional organizations on conference accessibility. We are keeping users centrally focused via surveys and user test groups, and holding paramount the overarching idea that meeting present accessibility standards is a necessary but insufficient condition for full access.

Barriers to primary care hospital follow-up among older adults in rural or semi-rural communities.

PubMed

Hardman, Bobbi; Newcomb, Patricia

2016-02-01

Failure to follow-up with a primary care provider (PCP) following discharge from an acute care setting is strongly associated with readmission within 90 days among elderly patients. The purpose of this study was to identify barriers to primary care follow-up among older adults in rural communities. This was an explanatory mixed methods study which included scaled survey and interview techniques. Descriptive and inferential statistics were calculated for scaled concepts. Standard content analysis was performed on the qualitative items. Correlation between intention to follow-up with a PCP and actual follow-up was poor (r=0.20). Patients encountered substantial obstacles to the PCP follow-up visit. Obstacles clustered into two groups: 1) healthcare or social system barriers and 2) personal characteristics of patients. Individualized discharge planning that reflects the complexities of post-hospitalization adaptation for elders is most likely to be useful for ensuring PCP follow-up. Copyright © 2015 Elsevier Inc. All rights reserved.

Carbon-based sputtered coatings for enhanced chitosan-based films properties

NASA Astrophysics Data System (ADS)

Fernandes, C.; Calderon V., S.; Ballesteros, Lina F.; Cerqueira, Miguel A.; Pastrana, L. M.; Teixeira, José A.; Ferreira, P. J.; Carvalho, S.

2018-03-01

In order to make bio-based packaging materials competitive in comparison to petroleum-based one, some of their properties need to be improved, among which gas permeability is of crucial importance. Thus, in this work, carbon-based coatings were applied on chitosan-based films by radiofrequency reactive magnetron sputtering aiming to improve their barrier properties. Chemical and morphological properties were evaluated in order to determine the effect of the coatings on the chemical structure, surface hydrophobicity and barrier properties of the system. Chemical analysis, performed by electron energy loss spectroscopy and Fourier transform infrared spectroscopy, suggests similar chemical characteristics among all coatings although higher incorporation of hydrogen as the acetylene flux increases was observed. On the other hand, scanning transmission electron microscopy revealed that the porosity of the carbon layer can be tailored by the acetylene flux. More importantly, the chitosan oxygen permeability showed a monotonic reduction as a function of the acetylene flux. This study opens up new opportunities to apply nanostructured coatings on bio-based polymer for enhanced oxygen barrier properties.