A New Approach in Force-Limited Vibration Testing of Flight Hardware

NASA Technical Reports Server (NTRS)

Kolaini, Ali R.; Kern, Dennis L.

2012-01-01

The force-limited vibration test approaches discussed in NASA-7004C were developed to reduce overtesting associated with base shake vibration tests of aerospace hardware where the interface responses are excited coherently. This handbook outlines several different methods of specifying the force limits. The rationale for force limiting is based on the disparity between the impedances of typical aerospace mounting structures and the large impedances of vibration test shakers when the interfaces in general are coherently excited. Among these approaches, the semi-empirical method is presently the most widely used method to derive the force limits. The inclusion of the incoherent excitation of the aerospace structures at mounting interfaces has not been accounted for in the past and provides the basis for more realistic force limits for qualifying the hardware using shaker testing. In this paper current methods for defining the force limiting specifications discussed in the NASA handbook are reviewed using data from a series of acoustic and vibration tests. A new approach based on considering the incoherent excitation of the structural mounting interfaces using acoustic test data is also discussed. It is believed that the new approach provides much more realistic force limits that may further remove conservatism inherent in shaker vibration testing not accounted for by methods discussed in the NASA handbook. A discussion on using FEM/BEM analysis to obtain realistic force limits for flight hardware is provided.

Getting into Issues: Good Government.

ERIC Educational Resources Information Center

Woodwell, William H., Jr.

1996-01-01

Provides a brief overview of the current arguments concerning campaign finance reform and congressional term limits. Discusses limits on spending, special interest contributions, "soft money," the power of incumbents, and the role of Political Action Committees. Includes a brief historical synopsis of campaign finance reform movements.…

Technical Study on Improvement of Endurance Capability of Limit Short-circuit Current of Charge Control SMART Meter

NASA Astrophysics Data System (ADS)

Li, W. W.; Du, Z. Z.; Yuan, R. m.; Xiong, D. Z.; Shi, E. W.; Lu, G. N.; Dai, Z. Y.; Chen, X. Q.; Jiang, Z. Y.; Lv, Y. G.

2017-10-01

Smart meter represents the development direction of energy-saving smart grid in the future. The load switch, one of the core parts of smart meter, should be of high reliability, safety and endurance capability of limit short-circuit current. For this reason, this paper discusses the quick simulation of relationship between attraction and counterforce of load switch without iteration, establishes dual response surface model of attraction and counterforce and optimizes the design scheme of load switch for charge control smart meter, thus increasing electromagnetic attraction and spring counterforce. In this way, this paper puts forward a method to improve the withstand capacity of limit short-circuit current.

About an Extreme Achievable Current in Plasma Focus Installation of Mather Type

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

Nikulin, V. Ya.; Polukhin, S. N.; Vikhrev, V. V.

A computer simulation and analytical analysis of the discharge process in Plasma Focus has shown that there is an upper limit to the current which can be achieved in Plasma Focus installation of Mather type by only increasing the capacity of the condenser bank. The maximum current achieved for various plasma focus installations of 1 MJ level is discussed. For example, for the PF-1000 (IFPiLM) and 1 MJ Frascati PF, the maximum current is near 2 MA. Thus, the commonly used method of increasing the energy of the PF installation by increasing of the capacity has no merit. Alternative optionsmore » in order to increase the current are discussed.« less

On the limit of field-aligned current intensity in the polar magnetosphere

NASA Technical Reports Server (NTRS)

Cole, Keith D.

1991-01-01

Field-aligned current (FAC) is here defined by 4 pi j = alpha B, where alpha is constant along a magnetic field line. The upper limit value of alpha in the polar magnetosphere, possible source regions of the strongest FAC and the relationship of them to some auroral and ionospheric irregularity cross-field scale sizes are discussed. Cross-field dimensions of the strongest FAC are related to the gyroradii of source particles (O(+), He(2+), He(+), H(+), e) in the current-generating region. It is suggested that experimental determination, and mapping of the values of alpha, may assist with the search for the generators of such currents in near-earth space including in the nearby solar wind. The upper limit of alpha is associated with the breakup of FAC systems.

Atomic Absorption Spectroscopy. The Present and the Future.

ERIC Educational Resources Information Center

Slavin, Walter

1982-01-01

The status of current techniques and methods of atomic absorption (AA) spectroscopy (flame, hybrid, and furnace AA) is discussed, including limitations. Technological opportunities and how they may be used in AA are also discussed, focusing on automation, microprocessors, continuum AA, hybrid analyses, and others. (Author/JN)

Space charge tune shift, fast resonance traversal, and current limits in circular accelerators

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

Rees, G.H.

1996-06-01

Space charge tune shifts, fast resonance traversals, and current limits are important design issues for low energy, high power circular accelerators. Areas of interest are accumulator rings and fast cycling synchrotrons, and typical applications are for pulsed spallation neutron sources, heavy ion fusion storage ring drivers, and booster injectors for high energy proton and ion facilities. Aspects of the three topics are discussed in the paper. {copyright} {ital 1996 American Institute of Physics.}

Evaluation of Bibliographic Instruction.

ERIC Educational Resources Information Center

Hardesty, Larry

Arguing that there is a current tendency among librarians to talk more about the evaluation of bibliographic instruction than to actually do anything about it, this paper examines limitations of and considerations pertaining to evaluation and includes: (1) a brief discussion of the history of bibliographic instruction; (2) discussion of types of…

Effects of Current Guides Destruction at Ultra-fast Acceleration of Macrobodies

NASA Astrophysics Data System (ADS)

Kataev, V. N.; Boriskin, A. S.; Golosov, S. N.; Demidov, V. A.; Klimashov, M. V.; Korolev, P. V.; Makartsev, G. F.; Pikar, A. S.; Russkov, A. S.; Shapovalov, E. V.; Shibitov, Yu. M.

2006-08-01

The paper is devoted to discussion of current guides destruction effects in different accelerators: thermal-electric and electro-magnetic rail accelerator at macrobodies acceleration value of 108-109 m/s2. Experimental results with thermal-electric accelerators powering from megajoule capacitor battery and helical magneto-cumulative generator MCG-100 at currents up to 3.5 MA are analyzed. The process of rails destruction at railgun at pressure magnetic field excess over the limit of metal fluidity is presented. Methods of efficiency coefficient increase of capacitive storage energy transmission to kinetic energy of accelerating body are discussed.

Moving receptor redirected adoptive cell therapy toward fine tuning of antitumor responses.

PubMed

Chicaybam, Leonardo; Bonamino, Martin Hernan

2014-10-01

Adoptive cell transfer (ACT) is emerging as a powerful modality of cancer treatment. While ACT has proved able to induce massive clinical responses, genetic modification of T lymphocytes further improved clinical responses obtained. One of the major current limitations of ACT is the inability to discern healthy from malignant cells, leading to on target/off tumor responses that can limit its application. We here discuss some of the approaches currently under development and potential solutions to circumvent these limitations and extend this potentially curative therapy to different tumors by targeting a variety of antigens.

Local structure studies of materials using pair distribution function analysis

NASA Astrophysics Data System (ADS)

Peterson, Joseph W.

A collection of pair distribution function studies on various materials is presented in this dissertation. In each case, local structure information of interest pushes the current limits of what these studies can accomplish. The goal is to provide insight into the individual material behaviors as well as to investigate ways to expand the current limits of PDF analysis. Where possible, I provide a framework for how PDF analysis might be applied to a wider set of material phenomena. Throughout the dissertation, I discuss 0 the capabilities of the PDF method to provide information pertaining to a material's structure and properties, ii) current limitations in the conventional approach to PDF analysis, iii) possible solutions to overcome certain limitations in PDF analysis, and iv) suggestions for future work to expand and improve the capabilities PDF analysis.

Data needs for X-ray astronomy satellites

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

Kallman, T.

I review the current status of atomic data for X-ray astronomy satellites. This includes some of the astrophysical issues which can be addressed, current modeling and analysis techniques, computational tools, the limitations imposed by currently available atomic data, and the validity of standard assumptions. I also discuss the future: challenges associated with future missions and goals for atomic data collection.

Chamber transport for heavy ion fusion

NASA Astrophysics Data System (ADS)

Olson, Craig L.

2014-01-01

A brief review is given of research on chamber transport for HIF (heavy ion fusion) dating from the first HIF Workshop in 1976 to the present. Chamber transport modes are categorized into ballistic transport modes and channel-like modes. Four major HIF reactor studies are summarized (HIBALL-II, HYLIFE-II, Prometheus-H, OSIRIS), with emphasis on the chamber transport environment. In general, many beams are used to provide the required symmetry and to permit focusing to the required small spots. Target parameters are then discussed, with a summary of the individual heavy ion beam parameters required for HIF. The beam parameters are then classified as to their line charge density and perveance, with special emphasis on the perveance limits for radial space charge spreading, for the space charge limiting current, and for the magnetic (Alfven) limiting current. The major experiments on ballistic transport (SFFE, Sabre beamlets, GAMBLE II, NTX, NDCX) are summarized, with specific reference to the axial electron trapping limit for charge neutralization. The major experiments on channel-like transport (GAMBLE II channel, GAMBLE II self-pinch, LBNL channels, GSI channels) are discussed. The status of current research on HIF chamber transport is summarized, and the value of future NDCX-II transport experiments for the future of HIF is noted.

Earth-based remote sensing of planetary surfaces and atmospheres at radio wavelengths

NASA Technical Reports Server (NTRS)

Dickel, J. R.

1982-01-01

Two reasons for remote sensing from the Earth are given: (1) space exploration, particularly below the surfaces or underneath cloud layers, is limited to only a very few planets; and (2) a program of regular monitoring, currently impractical with a limited number of space probes, is required. Reflected solar and nonthermal radiation are discussed. Relativistic electrons, trapped in large magnetospheres on Saturn and Jupiter, are discussed. These electrons produce synchrotron radiation and also interact with the ionosphere to produce bursts of low frequency emission. Because most objects are black-bodies, continuum radiometry is emphasized. Spectroscopic techniques and the measurement of nonthermal emission are also discussed.

Limitations Of The Current State Space Modelling Approach In Multistage Machining Processes Due To Operation Variations

NASA Astrophysics Data System (ADS)

Abellán-Nebot, J. V.; Liu, J.; Romero, F.

2009-11-01

The State Space modelling approach has been recently proposed as an engineering-driven technique for part quality prediction in Multistage Machining Processes (MMP). Current State Space models incorporate fixture and datum variations in the multi-stage variation propagation, without explicitly considering common operation variations such as machine-tool thermal distortions, cutting-tool wear, cutting-tool deflections, etc. This paper shows the limitations of the current State Space model through an experimental case study where the effect of the spindle thermal expansion, cutting-tool flank wear and locator errors are introduced. The paper also discusses the extension of the current State Space model to include operation variations and its potential benefits.

Experiment study on an inductive superconducting fault current limiter using no-insulation coils

NASA Astrophysics Data System (ADS)

Qiu, D.; Li, Z. Y.; Gu, F.; Huang, Z.; Zhao, A.; Hu, D.; Wei, B. G.; Huang, H.; Hong, Z.; Ryu, K.; Jin, Z.

2018-03-01

No-insulation (NI) coil made of 2 G high temperature superconducting (HTS) tapes has been widely used in DC magnet due to its excellent performance of engineering current density, thermal stability and mechanical strength. However, there are few AC power device using NI coil at present. In this paper, the NI coil is firstly applied into inductive superconducting fault current limiter (iSFCL). A two-winding structure air-core iSFCL prototype was fabricated, composed of a primary copper winding and a secondary no-insulation winding using 2 G HTS coated conductors. Firstly, in order to testify the feasibility to use NI coil as the secondary winding, the impedance variation of the prototype at different currents and different cycles was tested. The result shows that the impedance increases rapidly with the current rises. Then the iSFCL prototype was tested in a 40 V rms/ 3.3 kA peak short circuit experiment platform, both of the fault current limiting and recovery property of the iSFCL are discussed.

Looking Back To Find a Vision: Exploring the Emancipatory Potential of Teacher Research. Review of Research.

ERIC Educational Resources Information Center

Crawford, Patricia A.; Cornett, Jeffrey

2000-01-01

Discusses the limitations of experimental studies of learning and the emergence of alternative paradigms such as constructivism. Examines the growth of teacher research and its historical influences, including Montessori, Dewey's Progressive Movement, and Lucy Sprague Mitchell. Discusses current trends in teacher research, asserting that it is…

NASA contributions to radial turbine aerodynamic analyses

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1980-01-01

A brief description of the radial turbine and its analysis needs is followed by discussions of five analytical areas; design geometry and performance, off design performance, blade row flow, scroll flow, and duct flow. The functions of the programs, areas of applicability, and limitations and uncertainties are emphasized. Both past contributions and current activities are discussed.

Paradigm Change: Alternate Approaches to Constitutive and Necking Models for Sheet Metal Forming

NASA Astrophysics Data System (ADS)

Stoughton, Thomas B.; Yoon, Jeong Whan

2011-08-01

This paper reviews recent work proposing paradigm changes for the currently popular approach to constitutive and failure modeling, focusing on the use of non-associated flow rules to enable greater flexibility to capture the anisotropic yield and flow behavior of metals using less complex functions than those needed under associated flow to achieve that same level of fidelity to experiment, and on the use of stress-based metrics to more reliably predict necking limits under complex conditions of non-linear forming. The paper discusses motivating factors and benefits in favor of both associated and non-associated flow models for metal forming, including experimental, theoretical, and practical aspects. This review is followed by a discussion of the topic of the forming limits, the limitations of strain analysis, the evidence in favor of stress analysis, the effects of curvature, bending/unbending cycles, triaxial stress conditions, and the motivation for the development of a new type of forming limit diagram based on the effective plastic strain or equivalent plastic work in combination with a directional parameter that accounts for the current stress condition.

Equatorial oceanography. [review of research

NASA Technical Reports Server (NTRS)

Cane, M. A.; Sarachik, E. S.

1983-01-01

United States progress in equatorial oceanography is reviewed, focusing on the low frequency response of upper equatorial oceans to forcing by the wind. Variations of thermocline depth, midocean currents, and boundary currents are discussed. The factors which determine sea surface temperature (SST) variability in equatorial oceans are reviewed, and the status of understanding of the most spectacular manifestation of SST variability, the El Nino-Southern Oscillation phenomenon, is discussed. The problem of observing surface winds, regarded as a fundamental factor limiting understanding of the equatorial oceans, is addressed. Finally, an attempt is made to identify those current trends which are expected to bear fruit in the near and distant future.

Updates on Force Limiting Improvements

NASA Technical Reports Server (NTRS)

Kolaini, Ali R.; Scharton, Terry

2013-01-01

The following conventional force limiting methods currently practiced in deriving force limiting specifications assume one-dimensional translation source and load apparent masses: Simple TDOF model; Semi-empirical force limits; Apparent mass, etc.; Impedance method. Uncorrelated motion of the mounting points for components mounted on panels and correlated, but out-of-phase, motions of the support structures are important and should be considered in deriving force limiting specifications. In this presentation "rock-n-roll" motions of the components supported by panels, which leads to a more realistic force limiting specifications are discussed.

Computational Aerothermodynamic Design Issues for Hypersonic Vehicles

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.; Weilmuenster, K. James; Hamilton, H. Harris, II; Olynick, David R.; Venkatapathy, Ethiraj

1997-01-01

A brief review of the evolutionary progress in computational aerothermodynamics is presented. The current status of computational aerothermodynamics is then discussed, with emphasis on its capabilities and limitations for contributions to the design process of hypersonic vehicles. Some topics to be highlighted include: (1) aerodynamic coefficient predictions with emphasis on high temperature gas effects; (2) surface heating and temperature predictions for thermal protection system (TPS) design in a high temperature, thermochemical nonequilibrium environment; (3) methods for extracting and extending computational fluid dynamic (CFD) solutions for efficient utilization by all members of a multidisciplinary design team; (4) physical models; (5) validation process and error estimation; and (6) gridding and solution generation strategies. Recent experiences in the design of X-33 will be featured. Computational aerothermodynamic contributions to Mars Pathfinder, METEOR, and Stardust (Comet Sample return) will also provide context for this discussion. Some of the barriers that currently limit computational aerothermodynamics to a predominantly reactive mode in the design process will also be discussed, with the goal of providing focus for future research.

Computational Aerothermodynamic Design Issues for Hypersonic Vehicles

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.; Weilmuenster, K. James; Hamilton, H. Harris, II; Olynick, David R.; Venkatapathy, Ethiraj

2005-01-01

A brief review of the evolutionary progress in computational aerothermodynamics is presented. The current status of computational aerothermodynamics is then discussed, with emphasis on its capabilities and limitations for contributions to the design process of hypersonic vehicles. Some topics to be highlighted include: (1) aerodynamic coefficient predictions with emphasis on high temperature gas effects; (2) surface heating and temperature predictions for thermal protection system (TPS) design in a high temperature, thermochemical nonequilibrium environment; (3) methods for extracting and extending computational fluid dynamic (CFD) solutions for efficient utilization by all members of a multidisciplinary design team; (4) physical models; (5) validation process and error estimation; and (6) gridding and solution generation strategies. Recent experiences in the design of X-33 will be featured. Computational aerothermodynamic contributions to Mars Path finder, METEOR, and Stardust (Comet Sample return) will also provide context for this discussion. Some of the barriers that currently limit computational aerothermodynamics to a predominantly reactive mode in the design process will also be discussed, with the goal of providing focus for future research.

Computational Aerothermodynamic Design Issues for Hypersonic Vehicles

NASA Technical Reports Server (NTRS)

Olynick, David R.; Venkatapathy, Ethiraj

2004-01-01

A brief review of the evolutionary progress in computational aerothermodynamics is presented. The current status of computational aerothermodynamics is then discussed, with emphasis on its capabilities and limitations for contributions to the design process of hypersonic vehicles. Some topics to be highlighted include: (1) aerodynamic coefficient predictions with emphasis on high temperature gas effects; (2) surface heating and temperature predictions for thermal protection system (TPS) design in a high temperature, thermochemical nonequilibrium environment; (3) methods for extracting and extending computational fluid dynamic (CFD) solutions for efficient utilization by all members of a multidisciplinary design team; (4) physical models; (5) validation process and error estimation; and (6) gridding and solution generation strategies. Recent experiences in the design of X-33 will be featured. Computational aerothermodynamic contributions to Mars Pathfinder, METEOR, and Stardust (Comet Sample return) will also provide context for this discussion. Some of the barriers that currently limit computational aerothermodynamics to a predominantly reactive mode in the design process will also be discussed, with the goal of providing focus for future research.

Challenges in reducing dengue burden; diagnostics, control measures and vaccines.

PubMed

Lam, Sai Kit

2013-09-01

Dengue is a major public health concern worldwide, with the number of infections increasing globally. The illness imposes the greatest economic and human burden on developing countries that have limited resources to deal with the scale of the problem. No cure for dengue exists; treatment is limited to rehydration therapy, and with vector control strategies proving to be relatively ineffective, a vaccine is an urgent priority. Despite the numerous challenges encountered in the development of a dengue vaccine, several vaccine candidates have shown promise in clinical development and it is believed that a vaccination program would be at least as cost-effective as current vector control programs. The lead candidate vaccine is a tetravalent, live attenuated, recombinant vaccine, which is currently in Phase III clinical trials. Vaccine introduction is a complex process that requires consideration and is discussed here. This review discusses the epidemiology, burden and pathogenesis of dengue, as well as the vaccine candidates currently in clinical development.

Amorphous and Polycrystalline Photoconductors for Direct Conversion Flat Panel X-Ray Image Sensors

PubMed Central

Kasap, Safa; Frey, Joel B.; Belev, George; Tousignant, Olivier; Mani, Habib; Greenspan, Jonathan; Laperriere, Luc; Bubon, Oleksandr; Reznik, Alla; DeCrescenzo, Giovanni; Karim, Karim S.; Rowlands, John A.

2011-01-01

In the last ten to fifteen years there has been much research in using amorphous and polycrystalline semiconductors as x-ray photoconductors in various x-ray image sensor applications, most notably in flat panel x-ray imagers (FPXIs). We first outline the essential requirements for an ideal large area photoconductor for use in a FPXI, and discuss how some of the current amorphous and polycrystalline semiconductors fulfill these requirements. At present, only stabilized amorphous selenium (doped and alloyed a-Se) has been commercialized, and FPXIs based on a-Se are particularly suitable for mammography, operating at the ideal limit of high detective quantum efficiency (DQE). Further, these FPXIs can also be used in real-time, and have already been used in such applications as tomosynthesis. We discuss some of the important attributes of amorphous and polycrystalline x-ray photoconductors such as their large area deposition ability, charge collection efficiency, x-ray sensitivity, DQE, modulation transfer function (MTF) and the importance of the dark current. We show the importance of charge trapping in limiting not only the sensitivity but also the resolution of these detectors. Limitations on the maximum acceptable dark current and the corresponding charge collection efficiency jointly impose a practical constraint that many photoconductors fail to satisfy. We discuss the case of a-Se in which the dark current was brought down by three orders of magnitude by the use of special blocking layers to satisfy the dark current constraint. There are also a number of polycrystalline photoconductors, HgI2 and PbO being good examples, that show potential for commercialization in the same way that multilayer stabilized a-Se x-ray photoconductors were developed for commercial applications. We highlight the unique nature of avalanche multiplication in a-Se and how it has led to the development of the commercial HARP video-tube. An all solid state version of the HARP has been recently demonstrated with excellent avalanche gains; the latter is expected to lead to a number of novel imaging device applications that would be quantum noise limited. While passive pixel sensors use one TFT (thin film transistor) as a switch at the pixel, active pixel sensors (APSs) have two or more transistors and provide gain at the pixel level. The advantages of APS based x-ray imagers are also discussed with examples. PMID:22163893

Current status of one- and two-dimensional numerical models: Successes and limitations

NASA Technical Reports Server (NTRS)

Schwartz, R. J.; Gray, J. L.; Lundstrom, M. S.

1985-01-01

The capabilities of one and two-dimensional numerical solar cell modeling programs (SCAP1D and SCAP2D) are described. The occasions when a two-dimensional model is required are discussed. The application of the models to design, analysis, and prediction are presented along with a discussion of problem areas for solar cell modeling.

Efficiency limits for photoelectrochemical water-splitting

DOE PAGES

Fountaine, Katherine T.; Lewerenz, Hans Joachim; Atwater, Harry A.

2016-12-02

Theoretical limiting efficiencies have a critical role in determining technological viability and expectations for device prototypes, as evidenced by the photovoltaics community’s focus on detailed balance. However, due to their multicomponent nature, photoelectrochemical devices do not have an equivalent analogue to detailed balance, and reported theoretical efficiency limits vary depending on the assumptions made. Here we introduce a unified framework for photoelectrochemical device performance through which all previous limiting efficiencies can be understood and contextualized. Ideal and experimentally realistic limiting efficiencies are presented, and then generalized using five representative parameters—semiconductor absorption fraction, external radiative efficiency, series resistance, shunt resistance andmore » catalytic exchange current density—to account for imperfect light absorption, charge transport and catalysis. Finally, we discuss the origin of deviations between the limits discussed herein and reported water-splitting efficiencies. This analysis provides insight into the primary factors that determine device performance and a powerful handle to improve device efficiency.« less

Limits to magnetic resonance microscopy

NASA Astrophysics Data System (ADS)

Glover, Paul; Mansfield, Peter, Sir

2002-10-01

The last quarter of the twentieth century saw the development of magnetic resonance imaging (MRI) grow from a laboratory demonstration to a multi-billion dollar worldwide industry. There is a clinical body scanner in almost every hospital of the developed nations. The field of magnetic resonance microscopy (MRM), after mostly being abandoned by researchers in the first decade of MRI, has become an established branch of the science. This paper reviews the development of MRM over the last decade with an emphasis on the current state of the art. The fundamental principles of imaging and signal detection are examined to determine the physical principles which limit the available resolution. The limits are discussed with reference to liquid, solid and gas phase microscopy. In each area, the novel approaches employed by researchers to push back the limits of resolution are discussed. Although the limits to resolution are well known, the developments and applications of MRM have not reached their limit.

Alternative model of space-charge-limited thermionic current flow through a plasma

NASA Astrophysics Data System (ADS)

Campanell, M. D.

2018-04-01

It is widely assumed that thermionic current flow through a plasma is limited by a "space-charge-limited" (SCL) cathode sheath that consumes the hot cathode's negative bias and accelerates upstream ions into the cathode. Here, we formulate a fundamentally different current-limited mode. In the "inverse" mode, the potentials of both electrodes are above the plasma potential, so that the plasma ions are confined. The bias is consumed by the anode sheath. There is no potential gradient in the neutral plasma region from resistivity or presheath. The inverse cathode sheath pulls some thermoelectrons back to the cathode, thereby limiting the circuit current. Thermoelectrons entering the zero-field plasma region that undergo collisions may also be sent back to the cathode, further attenuating the circuit current. In planar geometry, the plasma density is shown to vary linearly across the electrode gap. A continuum kinetic planar plasma diode simulation model is set up to compare the properties of current modes with classical, conventional SCL, and inverse cathode sheaths. SCL modes can exist only if charge-exchange collisions are turned off in the potential well of the virtual cathode to prevent ion trapping. With the collisions, the current-limited equilibrium must be inverse. Inverse operating modes should therefore be present or possible in many plasma devices that rely on hot cathodes. Evidence from past experiments is discussed. The inverse mode may offer opportunities to minimize sputtering and power consumption that were not previously explored due to the common assumption of SCL sheaths.

Electrical properties of III-Nitride LEDs: Recombination-based injection model and theoretical limits to electrical efficiency and electroluminescent cooling

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

David, Aurelien, E-mail: adavid@soraa.com; Hurni, Christophe A.; Young, Nathan G.

The current-voltage characteristic and ideality factor of III-Nitride quantum well light-emitting diodes (LEDs) grown on bulk GaN substrates are investigated. At operating temperature, these electrical properties exhibit a simple behavior. A model in which only active-region recombinations have a contribution to the LED current is found to account for experimental results. The limit of LED electrical efficiency is discussed based on the model and on thermodynamic arguments, and implications for electroluminescent cooling are examined.

Dynamic array processing for computationally intensive expert systems in CLIPS

NASA Technical Reports Server (NTRS)

Athavale, N. N.; Ragade, R. K.; Fenske, T. E.; Cassaro, M. A.

1990-01-01

This paper puts forth an architecture for implementing a loop for advanced data structure of arrays in CLIPS. An attempt is made to use multi-field variables in such an architecture to process a set of data during the decision making cycle. Also, current limitations on the expert system shells are discussed in brief in this paper. The resulting architecture is designed to circumvent the current limitations set by the expert system shell and also by the operating environment. Such advanced data structures are needed for tightly coupling symbolic and numeric computation modules.

Grey's orthonormal optimization: a 50-year retrospective

NASA Astrophysics Data System (ADS)

Hayford, Michael J.

2014-12-01

The method of Grey's orthonormal optimization is reviewed. Aspects of the method that contributed to its success are reviewed, and factors limiting its application are discussed. Current status of the method is summarized.

Applicability of risk-based management and the need for risk-based economic decision analysis at hazardous waste contaminated sites.

PubMed

Khadam, Ibrahim; Kaluarachchi, Jagath J

2003-07-01

Decision analysis in subsurface contamination management is generally carried out through a traditional engineering economic viewpoint. However, new advances in human health risk assessment, namely, the probabilistic risk assessment, and the growing awareness of the importance of soft data in the decision-making process, require decision analysis methodologies that are capable of accommodating non-technical and politically biased qualitative information. In this work, we discuss the major limitations of the currently practiced decision analysis framework, which evolves around the definition of risk and cost of risk, and its poor ability to communicate risk-related information. A demonstration using a numerical example was conducted to provide insight on these limitations of the current decision analysis framework. The results from this simple ground water contamination and remediation scenario were identical to those obtained from studies carried out on existing Superfund sites, which suggests serious flaws in the current risk management framework. In order to provide a perspective on how these limitations may be avoided in future formulation of the management framework, more matured and well-accepted approaches to decision analysis in dam safety and the utility industry, where public health and public investment are of great concern, are presented and their applicability in subsurface remediation management is discussed. Finally, in light of the success of the application of risk-based decision analysis in dam safety and the utility industry, potential options for decision analysis in subsurface contamination management are discussed.

Delivering Advanced Methods in Mathematical Programming to Students of All Disciplines Using Abstraction, Modularity and Open-Ended Assignments

ERIC Educational Resources Information Center

Ezra, Elishai; Nahmias, Yaakov

2015-01-01

The advent of integrated multidisciplinary research has given rise to some of the most important breakthroughs of our time, but has also set significant challenges to the current educational paradigm. Current academic education often limits cross-discipline discussion, depends on close-ended problems, and restricts utilization of interdisciplinary…

Plasma density enhancements created by the ionization of the Earth's upper atmosphere by artificial electron beams

NASA Technical Reports Server (NTRS)

Neubert, Torsten; Banks, Peter M.

1990-01-01

Analytical calculations and experimental observations relating to the interaction with the Earth's upper atmosphere of electron beams emitted from low altitude spacecraft are presented. The problem is described by two coupled nonlinear differential equations in the up-going (along a magnetic field line) and down-going differential energy flux. The equations are solved numerically, using the MSIS atmospheric model and the IRI ionospheric model. The results form the model compare well with recent observations from the CHARGE 2 sounding rocket experiment. Two aspects of the beam-neutral atmosphere interaction are discussed. First, the limits on the electron beam current that can be emitted from a spacecraft without substantial spacecraft charging are investigated. This is important because the charging of the spacecraft to positive potentials limits the current and the escape energy of the beam electrons and thereby limits the ionization of the neutral atmosphere. As an example, we find from CHARGE 2 observations and from the model calculations that below about 180 km, secondary electrons generated through the ionization of the neutral atmosphere by 1 to 10 keV electron beams from sounding rockets, completely balance the beam current, thereby allowing the emission of very high beam currents. Second, the amount of plasma production in the beam-streak is discussed. Results are shown for selected values of the beam energy, spacecraft velocity, and spacecraft altitude.

A Four Channel Beam Current Monitor Data Acquisition System Using Embedded Processors

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

Wheat, Jr., Robert Mitchell; Dalmas, Dale A.; Dale, Gregory E.

2015-08-11

Data acquisition from multiple beam current monitors is required for electron accelerator production of Mo-99. A two channel system capable of recording data from two beam current monitors has been developed, is currently in use, and is discussed below. The development of a cost-effective method of extending this system to more than two channels and integrating of these measurements into an accelerator control system is the main focus of this report. Data from these current monitors is digitized, processed, and stored by a digital data acquisition system. Limitations and drawbacks with the currently deployed digital data acquisition system have beenmore » identified as have been potential solutions, or at least improvements, to these problems. This report will discuss and document the efforts we've made in improving the flexibility and lowering the cost of the data acquisition system while maintaining the minimum requirements.« less

Evaluation of bridge deck delamination investigation methods

DOT National Transportation Integrated Search

1998-07-01

An objective view of the relative advantages and limitations of the nondestructive, testing and evaluation methods that currently used in the inspection of bridge decks is presented and discussed. The three main nondestructive testing technologies th...

Global flowfield about the V-22 Tiltrotor Aircraft

NASA Technical Reports Server (NTRS)

Meakin, Robert L.

1995-01-01

The Chimera overset grid method is reviewed and discussed in the context of a method of solution and analysis of unsteady three-dimensional viscous flows. The state of maturity of the various pieces of support software required to use the approach is discussed. A variety of recent applications of the method is presented. Current limitations of the approach are identified.

The Chimera Method of Simulation for Unsteady Three-Dimensional Viscous Flow

NASA Technical Reports Server (NTRS)

Meakin, Robert L.

1996-01-01

The Chimera overset grid method is reviewed and discussed in the context of a method of solution and analysis of unsteady three-dimensional viscous flows. The state of maturity of the various pieces of support software required to use the approach is discussed. A variety of recent applications of the method is presented. Current limitations of the approach are defined.

Space-charge-limited currents for cathodes with electric field enhanced geometry

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

Lai, Dingguo, E-mail: laidingguo@nint.ac.cn; Qiu, Mengtong; Xu, Qifu

This paper presents the approximate analytic solutions of current density for annulus and circle cathodes. The current densities of annulus and circle cathodes are derived approximately from first principles, which are in agreement with simulation results. The large scaling laws can predict current densities of high current vacuum diodes including annulus and circle cathodes in practical applications. In order to discuss the relationship between current density and electric field on cathode surface, the existing analytical solutions of currents for concentric cylinder and sphere diodes are fitted from existing solutions relating with electric field enhancement factors. It is found that themore » space-charge-limited current density for the cathode with electric-field enhanced geometry can be written in a general form of J = g(β{sub E}){sup 2}J{sub 0}, where J{sub 0} is the classical (1D) Child-Langmuir current density, β{sub E} is the electric field enhancement factor, and g is the geometrical correction factor depending on the cathode geometry.« less

Title TBA: Revising the Abstract Submission Process.

PubMed

Tibon, Roni; Open Science Committee, Cbu; Henson, Richard

2018-04-01

Academic conferences are among the most prolific scientific activities, yet the current abstract submission and review process has serious limitations. We propose a revised process that would address these limitations, achieve some of the aims of Open Science, and stimulate discussion throughout the entire lifecycle of the scientific work. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

When the Social Justice Learning Curve Isn't as Steep: How a Social Foundations Course Changed the Conversation

ERIC Educational Resources Information Center

Cohen, Beth Douthirt; Tokunaga, Tomoko; Colvin, Demetrius J.; Mac, Jacqueline; Martinez, Judith Suyen; Leets, Craig; Lee, Douglas H.

2013-01-01

This article explores the limits of introductory social justice education and the ways in which a social foundations course could expand and deepen the social justice lens of current and future educators. The authors, members of an introductory graduate-level Social Foundations course, discuss the limitations they realized in their previous social…

On putative periodontal pathogens: an epidemiological perspective

PubMed Central

Lopez, Rodrigo; Hujoel, Philippe; Belibasakis, Georgios N

2015-01-01

The current understanding on the role of microbiology on periodontitis causation is reviewed. An appraisal of the literature reveals several issues that have limited the attempts to investigate candidate periodontal pathogens as causes of periodontitis and confirms that only limited epidemiological evidence is available. Several aspects of the contemporary understanding on causal inference are discussed with examples for periodontitis. PMID:25874553

Session on coupled atmospheric/chemistry coupled models

NASA Technical Reports Server (NTRS)

Thompson, Anne

1993-01-01

The session on coupled atmospheric/chemistry coupled models is reviewed. Current model limitations, current issues and critical unknowns, and modeling activity are addressed. Specific recommendations and experimental strategies on the following are given: multiscale surface layer - planetary boundary layer - chemical flux measurements; Eulerian budget study; and Langrangian experiment. Nonprecipitating cloud studies, organized convective systems, and aerosols - heterogenous chemistry are also discussed.

Piloted aircraft simulation concepts and overview

NASA Technical Reports Server (NTRS)

Sinacori, J. B.

1978-01-01

An overview of piloted aircraft simulation is presented that reflects the viewpoint of an aeronautical technologist. The intent is to acquaint potential users with some of the basic concepts and issues that characterize piloted simulation. Application to the development of aircraft are highlighted, but some aspects of training simulators are covered. A historical review is given together with a description of some current simulators. Simulator usages, advantages, and limitations are discussed and human perception qualities important to simulation are related. An assessment of current simulation is presented that addresses validity, fidelity, and deficiencies. Future prospects are discussed and technology projections are made.

CFD Methods and Tools for Multi-Element Airfoil Analysis

NASA Technical Reports Server (NTRS)

Rogers, Stuart E.; George, Michael W. (Technical Monitor)

1995-01-01

This lecture will discuss the computational tools currently available for high-lift multi-element airfoil analysis. It will present an overview of a number of different numerical approaches, their current capabilities, short-comings, and computational costs. The lecture will be limited to viscous methods, including inviscid/boundary layer coupling methods, and incompressible and compressible Reynolds-averaged Navier-Stokes methods. Both structured and unstructured grid generation approaches will be presented. Two different structured grid procedures are outlined, one which uses multi-block patched grids, the other uses overset chimera grids. Turbulence and transition modeling will be discussed.

Basics and recent advances in peptide and protein drug delivery

PubMed Central

Bruno, Benjamin J; Miller, Geoffrey D; Lim, Carol S

2014-01-01

While the peptide and protein therapeutic market has developed significantly in the past decades, delivery has limited their use. Although oral delivery is preferred, most are currently delivered intravenously or subcutaneously due to degradation and limited absorption in the gastrointestinal tract. Therefore, absorption enhancers, enzyme inhibitors, carrier systems and stability enhancers are being studied to facilitate oral peptide delivery. Additionally, transdermal peptide delivery avoids the issues of the gastrointestinal tract, but also faces absorption limitations. Due to proteases, opsonization and agglutination, free peptides are not systemically stable without modifications. This review discusses oral and transdermal peptide drug delivery, focusing on barriers and solutions to absorption and stability issues. Methods to increase systemic stability and site-specific delivery are also discussed. PMID:24228993

LIFE CYCLE IMPACT ASSESSMENT SOPHISTICATION

EPA Science Inventory

An international workshop was held in Brussels on 11/29-30/1998, to discuss LCIA Sophistication. LCA experts from North America, Europs, and Asia attended. Critical reviews of associated factors, including current limitations of available assessment methodologies, and comparison...

Supercomputer requirements for selected disciplines important to aerospace

NASA Technical Reports Server (NTRS)

Peterson, Victor L.; Kim, John; Holst, Terry L.; Deiwert, George S.; Cooper, David M.; Watson, Andrew B.; Bailey, F. Ron

1989-01-01

Speed and memory requirements placed on supercomputers by five different disciplines important to aerospace are discussed and compared with the capabilities of various existing computers and those projected to be available before the end of this century. The disciplines chosen for consideration are turbulence physics, aerodynamics, aerothermodynamics, chemistry, and human vision modeling. Example results for problems illustrative of those currently being solved in each of the disciplines are presented and discussed. Limitations imposed on physical modeling and geometrical complexity by the need to obtain solutions in practical amounts of time are identified. Computational challenges for the future, for which either some or all of the current limitations are removed, are described. Meeting some of the challenges will require computer speeds in excess of exaflop/s (10 to the 18th flop/s) and memories in excess of petawords (10 to the 15th words).

Aspects of the linguistic competence of deaf children.

PubMed

Wood, D

1984-02-01

In this paper the following three issues are considered in the light of recent research: Do severely/profoundly deaf children develop a grammar for English? Evidence is presented which suggests that they do and that this grammar displays a number of general characteristics some of which parallel the language of younger hearing children, others that do not. The limitations of this grammar will be discussed and hypotheses about the nature, origins and inevitability of such limitations explored. In what ways do the linguistic experiences of deaf children differ from that of hearing children? Some aspects of the deaf child's experience of language will be explored and their linguistic and psychological implications discussed. The relationships between current research findings on the linguistic development of the deaf and the possibility of improved educational methods will also be explored to consider the various different philosophies currently being debated in this field.

Suppression of nonsense mutations as a therapeutic approach to treat genetic diseases.

PubMed

Keeling, Kim M; Bedwell, David M

2011-01-01

Suppression therapy is a treatment strategy for genetic diseases caused by nonsense mutations. This therapeutic approach utilizes pharmacological agents that suppress translation termination at in-frame premature termination codons (PTCs) to restore translation of a full-length, functional polypeptide. The efficiency of various classes of compounds to suppress PTCs in mammalian cells is discussed along with the current limitations of this therapy. We also elaborate on approaches to improve the efficiency of suppression that include methods to enhance the effectiveness of current suppression drugs and the design or discovery of new, more effective suppression agents. Finally, we discuss the role of nonsense-mediated mRNA decay (NMD) in limiting the effectiveness of suppression therapy, and describe tactics that may allow the efficiency of NMD to be modulated in order to enhance suppression therapy. Copyright © 2011 John Wiley & Sons, Ltd.

Large Eddy Simulation study of the development of finite-channel lock-release currents at high Grashof numbers

NASA Astrophysics Data System (ADS)

Ooi, Seng-Keat

2005-11-01

Lock-exchange gravity current flows produced by the instantaneous release of a heavy fluid are investigated using 3-D well resolved Large Eddy Simulation simulations at Grashof numbers up to 8*10^9. It is found the 3-D simulations correctly predict a constant front velocity over the initial slumping phase and a front speed decrease proportional to t-1/3 (the time t is measured from the release) over the inviscid phase, in agreement with theory. The evolution of the current in the simulations is found to be similar to that observed experimentally by Hacker et al. (1996). The effect of the dynamic LES model on the solutions is discussed. The energy budget of the current is discussed and the contribution of the turbulent dissipation to the total dissipation is analyzed. The limitations of less expensive 2D simulations are discussed; in particular their failure to correctly predict the spatio-temporal distributions of the bed shear stresses which is important in determining the amount of sediment the gravity current can entrain in the case in advances of a loose bed.

Learning leadership skills in practice through quality improvement.

PubMed

Gamble, James; Vaux, Emma

2014-02-01

The development of leadership skills in doctors in training is essential to support both their professional development and the future supply of clinical leaders the NHS so desperately needs. There is, however, limited opportunity in current training programmes for trainees to learn and develop these skills, and what opportunity there is has often focused on management rather than leadership skills. Involvement in trainee-led supported quality improvement projects can teach these skills. We summarise the current limitations in leadership training and discuss how the College's 'Learning To Make a Difference' programme, and others like it, are helping to teach leadership.

Public health services and systems research: current state of finance research.

PubMed

Ingram, Richard C; Bernet, Patrick M; Costich, Julia F

2012-11-01

There is a growing recognition that the US public health system should strive for efficiency-that it should determine the optimal ways to utilize limited resources to improve and protect public health. The field of public health finance research is a critical part of efforts to understand the most efficient ways to use resources. This article discusses the current state of public health finance research through a review of public health finance literature, chronicles important lessons learned from public health finance research to date, discusses the challenges faced by those seeking to conduct financial research on the public health system, and discusses the role of public health finance research in relation to the broader endeavor of Public Health Services and Systems Research.

Coming to terms with tissue engineering and regenerative medicine in the lung

PubMed Central

Tschumperlin, Daniel J.; Stenmark, Kurt R.

2015-01-01

Lung diseases such as emphysema, interstitial fibrosis, and pulmonary vascular diseases cause significant morbidity and mortality, but despite substantial mechanistic understanding, clinical management options for them are limited, with lung transplantation being implemented at end stages. However, limited donor lung availability, graft rejection, and long-term problems after transplantation are major hurdles to lung transplantation being a panacea. Bioengineering the lung is an exciting and emerging solution that has the ultimate aim of generating lung tissues and organs for transplantation. In this article we capture and review the current state of the art in lung bioengineering, from the multimodal approaches, to creating anatomically appropriate lung scaffolds that can be recellularized to eventually yield functioning, transplant-ready lungs. Strategies for decellularizing mammalian lungs to create scaffolds with native extracellular matrix components vs. de novo generation of scaffolds using biocompatible materials are discussed. Strengths vs. limitations of recellularization using different cell types of various pluripotency such as embryonic, mesenchymal, and induced pluripotent stem cells are highlighted. Current hurdles to guide future research toward achieving the clinical goal of transplantation of a bioengineered lung are discussed. PMID:26254424

The uncertainty principle in resonant gravitational wave antennae and quantum non-demolition measurement schemes

NASA Technical Reports Server (NTRS)

Fortini, Pierluigi; Onofrio, Roberto; Rioli, Alessandro

1993-01-01

A review of current efforts to approach and to surpass the fundamental limit in the sensitivity of the Weber type gravitational wave antennae is reported. Applications of quantum non-demolition techniques to the concrete example of an antenna resonant with the transducer are discussed in detail. Analogies and differences from the framework of the squeezed states in quantum optics are discussed.

Computerized design of speech prostheses.

PubMed

Leonard, R J

1991-08-01

The use of computerized techniques to assist in the design of palatal and/or glossal prostheses is described. Patients with oropharyngeal resection and associated speech impairment are candidates for such prostheses. Procedures discussed allow for the design of some features of the prosthesis, such as shape, location, and tests of its effect on certain speech parameters, prior to actual fabrication. Advantages and current limitations of the techniques are also discussed.

Validation of Finite-Element Models of Persistent-Current Effects in Nb 3Sn Accelerator Magnets

DOE PAGES

Wang, X.; Ambrosio, G.; Chlachidze, G.; ...

2015-01-06

Persistent magnetization currents are induced in superconducting filaments during the current ramping in magnets. The resulting perturbation to the design magnetic field leads to field quality degradation, in particular at low field where the effect is stronger relative to the main field. The effects observed in NbTi accelerator magnets were reproduced well with the critical-state model. However, this approach becomes less accurate for the calculation of the persistent-current effects observed in Nb 3Sn accelerator magnets. Here a finite-element method based on the measured strand magnetization is validated against three state-of-art Nb3Sn accelerator magnets featuring different subelement diameters, critical currents, magnetmore » designs and measurement temperatures. The temperature dependence of the persistent-current effects is reproduced. Based on the validated model, the impact of conductor design on the persistent current effects is discussed. The performance, limitations and possible improvements of the approach are also discussed.« less

SQUID magnetometers for low-frequency applications

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

Ryhaenen, T.; Seppae, H.; Ilmoniemi, R.

1989-09-01

The authors present a novel formulation for SQUID operation, which enables them to evaluate and compare the sensitivity and applicability of different devices. SQUID magnetometers for low-frequency applications are analyzed, taking into account the coupling circuits and electronics. They discuss nonhysteretic and hysteretic single-junction rf SQUIDs, but the main emphasis is on the dynamics, sensitivity, and coupling considerations of dc-SQUID magnetometers. A short review of current ideas on thin-film, dc-SQUID design presents the problems in coupling and the basic limits of sensitivity. The fabrication technology of tunnel-junction devices is discussed with emphasis on how it limits critical current densities, specificmore » capacitances of junctions, minimum linewidths, conductor separations, etc. Properties of high-temperature superconductors are evaluated on the basis of recently published results on increased flux creep, low density of current carriers, and problems in fabricating reliable junctions. The optimization of electronics for different types of SQUIDs is presented. Finally, the most important low-frequency applications of SQUIDs in biomagnetism, metrology, geomagnetism, and some physics experiments demonstrate the various possibilities that state-of-the-art SQUIDs can provide.« less

Development of a particle-trap preconcentration-soft ionization mass spectrometric technique for the quantification of mercury halides in air.

PubMed

Deeds, Daniel A; Ghoshdastidar, Avik; Raofie, Farhad; Guérette, Élise-Andrée; Tessier, Alain; Ariya, Parisa A

2015-01-01

Measurement of oxidized mercury, Hg(II), in the atmosphere poses a significant analytical challenge as Hg(II) is present at ultra-trace concentrations (picograms per cubic meter air). Current technologies are sufficiently sensitive to measure the total Hg present as Hg(II) but cannot determine the chemical speciation of Hg(II). We detail here the development of a soft ionization mass spectrometric technique coupled with preconcentration onto nano- or microparticle-based traps prior to analysis for the measurement of mercury halides in air. The current methodology has comparable detection limits (4-11 pg m(-3)) to previously developed techniques for the measurement of total inorganic mercury in air while allowing for the identification of HgX2 in collected samples. Both mercury chloride and mercury bromide have been sporadically detected in Montreal urban and indoor air using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). We discuss limitations and advantages of the current technique and discuss potential avenues for future research including quantitative trace measurements of a larger range of mercury compounds.

Comparative study of CAVET with dielectric and p-GaN gate and Mg ion-implanted current blocking layer

NASA Astrophysics Data System (ADS)

Mandal, Saptarshi; Agarwal, Anchal; Ahmadi, Elaheh; Mahadeva Bhat, K.; Laurent, Matthew A.; Keller, Stacia; Chowdhury, Srabanti

2017-08-01

In this work, a study of two different types of current aperture vertical electron transistor (CAVET) with ion-implanted blocking layer are presented. The device fabrication and performance limitation of a CAVET with a dielectric gate is discussed, and the breakdown limiting structure is evaluated using on-wafer test structures. The gate dielectric limited the device breakdown to 50V, while the blocking layer was able to withstand over 400V. To improve the device performance, an alternative CAVET structure with a p-GaN gate instead of dielectric is designed and realized. The pGaN gated CAVET structure increased the breakdown voltage to over 400V. Measurement of test structures on the wafer showed the breakdown was limited by the blocking layer instead of the gate p-n junction.

International Legal Framework for Denuclearization and Nuclear Disarmament -- Present Situation and Prospects

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

Gastelum, Zoe N.

This thesis is the culminating project for my participation in the OECD NEA International School of Nuclear Law. This paper will begin by providing a historical background to current disarmament and denuclearization treaties. This paper will discuss the current legal framework based on current and historical activities related to denuclearization and nuclear disarmament. Then, it will propose paths forward for the future efforts, and describe the necessary legal considerations. Each treaty or agreement will be examined in respect to its requirements for: 1) limitations and implementation; 2) and verification and monitoring. Then, lessons learned in each of the two areasmore » (limitations and verification) will be used to construct a proposed path forward at the end of this paper.« less

Current transcatheter devices to treat functional tricuspid regurgitation with discussion of issues relevant to clinical trial design

PubMed Central

2017-01-01

Functional or secondary tricuspid regurgitation (TR) has seen increased attention in recent times as relationships with clinically-relevant outcomes have come to light. Despite the association of increased mortality with significant TR, the disease remains under-recognized and thus relatively untreated. In addition, the disease itself has not been extensively studied and the interactions between annular dilatation, right heart disease and pulmonary hypertension are poorly understood. However, the high mortality and recurrence rate with current surgical replacement or repair techniques is well recognised, opening the door to transcatheter therapies for functional TR. The current perspective reviews the rationale for transcatheter solutions, describes some of the current approaches and discusses the ongoing questions of a poorly-studied condition which may limit the design of clinical trials for this disease. PMID:28706866

Feasibility of producing a range of food products from a limited range of undifferenitiated major food components

NASA Technical Reports Server (NTRS)

Karel, M.; Kamarei, A. R.

1984-01-01

This report reviews current knowledge associated with producing safe, nutritious, and acceptable foods from a limited number of source independent macronutrients. The advantages, and disadvantages, of such an approach for use by space crews are discussed. The production of macronutrients from a variety of sources is covered in detail. The sources analyzed are: wheat, soybeans, algae (3 genera), glycerol, and digested cellulose. Fabrication of food from the above macronutrient sources is discussed and particular attention is addressed to nutrition, acceptability and reliability. The processes and concepts involved in food fabrication and macronutrient production are also considered for utilization in a space environment.

An integrated view of cisplatin-induced nephrotoxicity and ototoxicity

PubMed Central

Karasawa, Takatoshi; Steyger, Peter S.

2015-01-01

Cisplatin is one of the most widely-used drugs to treat cancers. However, its nephrotoxic and ototoxic side-effects remain major clinical limitations. Recent studies have improved our understanding of the molecular mechanisms of cisplatin-induced nephrotoxicity and ototoxicity. While cisplatin binding to DNA is the major cytotoxic mechanism in proliferating (cancer) cells, nephrotoxicity and ototoxicity appear to result from toxic levels of reactive oxygen species and protein dysregulation within various cellular compartments. In this review, we discuss molecular mechanisms of cisplatin-induced nephrotoxicity and ototoxicity. We also discuss potential clinical strategies to prevent nephrotoxicity and ototoxicity and their current limitations. PMID:26101797

Energy and Economic Impacts of Projected Freight Transportation Improvements

DOT National Transportation Integrated Search

1977-05-01

This study examines current and future energy impacts for each major freight mode, by commodity, and, in many cases, by vehicle types. It also discusses potential economic impacts of these anticipated changes. The study is limited to intercity freigh...

Direct Determination of Nonmetals in Solution with Atomic Spectrometry.

ERIC Educational Resources Information Center

McGregor, David A.; And Others

1988-01-01

Addresses solution nonmetal determinations on a fundamental level. Characterizes research in this area of chemical instrumentation. Discusses the fundamental limitations of nonmetal atomic spectrometry, the status of nonmetals and atomic spectroscopic techniques, and current directions in solution nonmetal determinations. (CW)

Virtual Reality: Real Promises and False Expectations.

ERIC Educational Resources Information Center

Homan, Willem J.

1994-01-01

Examines virtual reality (VR), and discusses the dilemma of defining VR, the limitations of the current technology, and the implications of VR for education. Highlights include a VR experience; human factors and the interface; and altered reality versus VR. (Author/AEF)

Eddy current damper

NASA Technical Reports Server (NTRS)

Ellis, R. C.; Fink, R. A.; Rich, R. W.

1989-01-01

A high torque capacity eddy current damper used as a rate limiting device for a large solar array deployment mechanism is discussed. The eddy current damper eliminates the problems associated with the outgassing or leaking of damping fluids. It also provides performance advantages such as damping torque rates, which are truly linear with respect to input speed, continuous 360 degree operation in both directions of rotation, wide operating temperature range, and the capability of convenient adjustment of damping rates by the user without disassembly or special tools.

Modeling of Photoionized Plasmas

NASA Technical Reports Server (NTRS)

Kallman, Timothy R.

2010-01-01

In this paper I review the motivation and current status of modeling of plasmas exposed to strong radiation fields, as it applies to the study of cosmic X-ray sources. This includes some of the astrophysical issues which can be addressed, the ingredients for the models, the current computational tools, the limitations imposed by currently available atomic data, and the validity of some of the standard assumptions. I will also discuss ideas for the future: challenges associated with future missions, opportunities presented by improved computers, and goals for atomic data collection.

Detecting terrorist nuclear weapons at sea: The 10th door problem

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

Slaughter, D R

2008-09-15

While screening commercial cargo containers for the possible presence of WMD is important and necessary smugglers have successfully exploited the many other vehicles transporting cargo into the US including medium and small vessels at sea. These vessels provide a venue that is currently not screened and widely used. Physics limits that make screening of large vessels prohibitive impractical do not prohibit effective screening of the smaller vessels. While passive radiation detection is probably ineffective at sea active interrogation may provide a successful approach. The physics limits of active interrogation of ships at sea from standoff platforms are discussed. Autonomous platformsmore » that could carry interrogation systems at sea, both airborne and submersible, are summarized and their utilization discussed. An R&D program to investigate the limits of this approach to screening ships at sea is indicated and limitations estimated.« less

Fluidized combustion of coal. [to limit SO2 and NOx emissions

NASA Technical Reports Server (NTRS)

Pope, M.

1978-01-01

A combustion technology that permits the burning of low quality coal, and other fuels, while maintaining stack emissions within State and Federal EPA limits is discussed. Low quality fuels can be burned directly in fluidized beds while taking advantage of low furnace temperatures and chemical activity within the bed to limit SO2 and NOx emissions. The excellent heat transfer characteristics of the fluidized beds also result in a reduction of total heat transfer surface requirements. Tests on beds operating at pressures of one to ten atmospheres, at temperatures as high as 1600 F, and with gas velocities in the vicinity of four to twelve feet per second, have proven the concept. The progress that has been made in the development of fluidized bed combustion technology and work currently underway are discussed.

The uncertainty principle in resonant gravitational wave antennae and quantum non-demolition measurement schemes

NASA Technical Reports Server (NTRS)

Fortini, Pierluigi; Onofrio, Roberto; Rioli, Alessandro

1993-01-01

A review on the current efforts to approach and to surpass the fundamental limit in the sensitivity of the Weber type gravitational wave antennae is reported. Applications of quantum non-demolition techniques to the concrete example of an antenna resonant with the transducer are discussed in detail. Analogies and differences from the framework of the squeezed states in quantum optics are discussed.

Alternative model of space-charge-limited thermionic current flow through a plasma

DOE PAGES

Campanell, M. D.

2018-04-19

It is widely assumed that thermionic current flow through a plasma is limited by a “space-charge-limited” (SCL) cathode sheath that consumes the hot cathode's negative bias and accelerates upstream ions into the cathode. In this paper, we formulate a fundamentally different current-limited mode. In the “inverse” mode, the potentials of both electrodes are above the plasma potential, so that the plasma ions are confined. The bias is consumed by the anode sheath. There is no potential gradient in the neutral plasma region from resistivity or presheath. The inverse cathode sheath pulls some thermoelectrons back to the cathode, thereby limiting themore » circuit current. Thermoelectrons entering the zero-field plasma region that undergo collisions may also be sent back to the cathode, further attenuating the circuit current. In planar geometry, the plasma density is shown to vary linearly across the electrode gap. A continuum kinetic planar plasma diode simulation model is set up to compare the properties of current modes with classical, conventional SCL, and inverse cathode sheaths. SCL modes can exist only if charge-exchange collisions are turned off in the potential well of the virtual cathode to prevent ion trapping. With the collisions, the current-limited equilibrium must be inverse. Inverse operating modes should therefore be present or possible in many plasma devices that rely on hot cathodes. Evidence from past experiments is discussed. Finally, the inverse mode may offer opportunities to minimize sputtering and power consumption that were not previously explored due to the common assumption of SCL sheaths.« less

Alternative model of space-charge-limited thermionic current flow through a plasma

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

Campanell, M. D.

It is widely assumed that thermionic current flow through a plasma is limited by a “space-charge-limited” (SCL) cathode sheath that consumes the hot cathode's negative bias and accelerates upstream ions into the cathode. In this paper, we formulate a fundamentally different current-limited mode. In the “inverse” mode, the potentials of both electrodes are above the plasma potential, so that the plasma ions are confined. The bias is consumed by the anode sheath. There is no potential gradient in the neutral plasma region from resistivity or presheath. The inverse cathode sheath pulls some thermoelectrons back to the cathode, thereby limiting themore » circuit current. Thermoelectrons entering the zero-field plasma region that undergo collisions may also be sent back to the cathode, further attenuating the circuit current. In planar geometry, the plasma density is shown to vary linearly across the electrode gap. A continuum kinetic planar plasma diode simulation model is set up to compare the properties of current modes with classical, conventional SCL, and inverse cathode sheaths. SCL modes can exist only if charge-exchange collisions are turned off in the potential well of the virtual cathode to prevent ion trapping. With the collisions, the current-limited equilibrium must be inverse. Inverse operating modes should therefore be present or possible in many plasma devices that rely on hot cathodes. Evidence from past experiments is discussed. Finally, the inverse mode may offer opportunities to minimize sputtering and power consumption that were not previously explored due to the common assumption of SCL sheaths.« less

Ultrasensitive optofluidic-nanoplasmonic BioNEMS for life sciences and point-of-care diagnostics

NASA Astrophysics Data System (ADS)

Yanik, Ahmet Ali

2014-03-01

Recent progress on the development of optofluidic-nanoplasmonic BioNEMS is reviewed in this proceeding. Following a brief summary of the fundamental limitations in current lab-on-chip platforms, optofluidic-nanoplasmonic BioNEMS are discussed in detail and means to overcome mass transport limitations are shown. Finally, nanofluidic approach is extended to a cross fluidic scheme for efficiently isolation of rare circulating tumor cells.

Applications of artificial neural nets in clinical biomechanics.

PubMed

Schöllhorn, W I

2004-11-01

The purpose of this article is to provide an overview of current applications of artificial neural networks in the area of clinical biomechanics. The body of literature on artificial neural networks grew intractably vast during the last 15 years. Conventional statistical models may present certain limitations that can be overcome by neural networks. Artificial neural networks in general are introduced, some limitations, and some proven benefits are discussed.

Current Status and Future of Skin Substitutes for Chronic Wound Healing.

PubMed

Nicholas, Mathew N; Yeung, Jensen

Chronic wounds, including diabetic ulcers, pressure ulcers, venous ulcers, and arterial insufficiency ulcers, are both difficult and expensive to treat. Conventional wound care may sometimes lead to suboptimal wound healing and significant morbidity and mortality for patients. The use of skin substitutes provides an alternative therapy showing superior efficacy and, in some cases, similar cost-effectiveness compared to traditional treatments. This review discusses the different types of currently available commercial skin substitutes for use in chronic wounds as well as the paucity of strong evidence supporting their use. It then delves into the limitations of these skin substitutes and examines the most recent research targeting these limitations.

Implications of Metaphors in Defining Technical Communication.

ERIC Educational Resources Information Center

Beck, Charles E.

1991-01-01

Identifies four metaphors that appear dominant in current studies in the field of technical communication: transmitter, channel, balance, and bridge. Suggests limitations upon each of the metaphors. Discusses the alternative metaphors of lock, translator, transformer, synthesizer, conductor, and orchestrator. Proposes orchestration as a fruitful…

Current limitations and recommendations to improve testing for the environmental assessment of endocrine active substances

EPA Science Inventory

In this paper existing regulatory frameworks and test systems for assessing potential endocrine-active chemicals are described, and associated challenges discussed, along with proposed approaches to address these challenges. Regulatory frameworks vary somewhat across organizatio...

Drug Abuse, U.S.A.: How Serious? How Soluble?

ERIC Educational Resources Information Center

Pollin, William

1987-01-01

Discusses the findings of the 1986 National Institute on Drug Abuse household survey. Points out the limitations of the survey and identifies trends associated with drug use. Reviews current efforts in dealing with the drug problem and recommends specific policy changes. (ML)

Daddy, I'm Scared: A Prophetic Parable.

ERIC Educational Resources Information Center

Conley, David T.

1996-01-01

Although some small liberal arts colleges feature developmentally appropriate programs, most postsecondary institutions are more like factories that process students. This article describes limitations of the current college-admissions model and discusses the need to create common expectations and develop performance-based admission standards…

Event-driven simulations of nonlinear integrate-and-fire neurons.

PubMed

Tonnelier, Arnaud; Belmabrouk, Hana; Martinez, Dominique

2007-12-01

Event-driven strategies have been used to simulate spiking neural networks exactly. Previous work is limited to linear integrate-and-fire neurons. In this note, we extend event-driven schemes to a class of nonlinear integrate-and-fire models. Results are presented for the quadratic integrate-and-fire model with instantaneous or exponential synaptic currents. Extensions to conductance-based currents and exponential integrate-and-fire neurons are discussed.

Work Requirements in Transformation, Competence for the Future: A Critical Look at the Consequences of Current Positions. IAB Labour Market Research Topics No. 45.

ERIC Educational Resources Information Center

Plath, Hans-Eberhard

In Germany and elsewhere, the literature on current and future work requirements rarely discusses the effects of globalization, internationalization, computerization, and other factors from the point of view of workers. Some have suggested that a blurring of limits will be one of the main changes in work in the future. This blurring will involve…

A review of current methods using bacteriophages in live animals, food and animal products intended for human consumption.

PubMed

Cooper, Ian R

2016-11-01

Bacteriophages are utilised in the food industry as biocontrol agents to reduce the load of bacteria, and thus reduce potential for human infection. This review focuses on current methods using bacteriophages within the food chain. Limitations of research will be discussed, and the potential for future food-based bacteriophage research. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrical safety Q&A. A reference guide for the clinical engineer.

PubMed

2005-02-01

This guide, which ECRI developed to answer the electrical safety questions most frequently asked by member hospitals, features practical advice for addressing electrical safety concerns in the healthcare environment. Questions addressed include: STANDARDS AND APPROVALS: What electrical safety standards apply? How do NFPA 99 and IEC 60601-1 differ? What organizations approve medical devices? LEAKAGE CURRENT LIMITS AND TESTING: How are leakage current limits established? What limits apply to equipment used in the hospital? And how should the limits be applied in special cases, such as the use of PCs in the patient care area or equipment used in the clinical laboratory? ISOLATED POWER: What are its advantages and disadvantages, and is isolated power needed in the operating room? Other topics addressed include double insulation, ground-fault circuit interrupters (GFCIs), and requirements for medical devices used in the home. Supplementary articles discuss acceptable alternatives to UL listing, the use of Hospital Grade plugs, the limitations of leakage current testing of devices connected to isolated power systems, and the debate about whether to designate ORs as wet locations. Experienced clinical engineers should find this guide to be a handy reference, while those new to the field should find it to be a helpful educational resource.

Dental epidemiology of military operations.

PubMed

Chisick, M C; King, J E

1993-09-01

In this paper we review studies that have been conducted on the epidemiology of oral, dental, and maxillofacial conditions during military deployments. The limitations of our current knowledge base are discussed, as is a proposed research effort to enhance the responsiveness of dental support in theaters of operation.

Virtual Reality: A Strategy for Training in Cross-Cultural Communication.

ERIC Educational Resources Information Center

Meyer, Catherine; Dunn-Roberts, Richard

1992-01-01

Defines virtual reality and explains terminology, theoretical concepts, and enabling technologies. Research and applications are described; limitations of current technology are considered; and future possibilities are discussed, including the use of virtual reality in training for cross-cultural communication. (22 references) (LRW)

Toxicity Bioassays for Ecological Risk Assessment in Arid and Semiarid Ecosystems. Reviews Environmental Contamination and Toxicology 168:43-98.

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

Markwiese, J.T.; Ryti, R.T.; Hooten, M.M.

2001-02-01

This paper discusses current limitations for performing ecological risk assessments in dry environments (i.e., ecosystems that are characteristic of many DOE Facilities) and presents novel approaches to addressing ecological risk in such systems.

Thin-needle aspiration biopsy of the prostate.

PubMed

Koss, L G; Woyke, S; Schreiber, K; Kohlberg, W; Freed, S Z

1984-05-01

The authors summarize the current status of thin-needle aspiration biopsy of the prostate and evaluate the accomplishments and limitations of this method of diagnosis. Historical developments, indications, technique, contraindications, complications, cytology of aspirates, diagnostic efficacy of aspirates, and grading of prostatic carcinomas are discussed.

Measurements of high-current electron beams from X pinches and wire array Z pinches.

PubMed

Shelkovenko, T A; Pikuz, S A; Blesener, I C; McBride, R D; Bell, K S; Hammer, D A; Agafonov, A V; Romanova, V M; Mingaleev, A R

2008-10-01

Some issues concerning high-current electron beam transport from the X pinch cross point to the diagnostic system and measurements of the beam current by Faraday cups are discussed. Results of computer simulation of electron beam propagation from the pinch to the Faraday cup give limits for the measured current for beams having different energy spreads. The beam is partially neutralized as it propagates from the X pinch to a diagnostic system, but within a Faraday cup diagnostic, space charge effects can be very important. Experimental results show evidence of such effects.

Tribological Limitations in Gas Turbine Engines: A Workshop to Identify the Challenges and Set Future Directions

NASA Technical Reports Server (NTRS)

DellaCorte, Chris; Pinkus, Oscar

2000-01-01

The following report represents a compendium of selected speaker presentation materials and observations made by Prof O. Pinkus at the NASA/ASME/Industry sponsored workshop entitled "Tribological Limitations in Gas Turbine Engines" held on September 15-17, 1999 in Albany, New York. The impetus for the workshop came from the ASME's Research Committee on Tribology whose goal is to explore new tribological research topics which may become future research opportunities. Since this subject is of current interest to other industrial and government entities the conference received cosponsorship as noted above. The conference was well attended by government, industrial and academic participants. Topics discussed included current tribological issues in gas turbines as well as the potential impact (drawbacks and advantages) of future tribological technologies especially foil air bearings and magnetic beatings. It is hoped that this workshop report may serve as a starting point for continued discussions and activities in oil-free turbomachinery systems.

Tribological Limitations in Gas Turbine Engines: A Workshop to Identify the Challenges and Set Future Directions. Revised

NASA Technical Reports Server (NTRS)

DellaCorte, Chris; Pinkus, Oscar

2002-01-01

The following report represents a compendium of selected speaker presentation materials and observations made by Prof. O. Pinkus at the NASA/ASME/Industry sponsored workshop entitled "Tribological Limitations in Gas Turbine Engines" held on September 15-17, 1999 in Albany, New York. The impetus for the workshop came from the ASME's Research Committee on tribology whose goal is to explore new tribological research topics which may become future research opportunities. Since this subject is of current interest to other industrial and government entities the conference received cosponsorship as noted above. The conference was well attended by government, industrial, and academic participants. Topics discussed included current tribological issues in gas turbines as well as the potential impact (drawbacks and advantages) of future tribological technologies especially foil air bearings and magnetic bearings. It is hoped that this workshop report may serve as a starting point for continued discussions and activities in oil-free turbomachinery systems.

An Analysis of Proposed and Current Regulations Concerning Lobbying Costs in Department of Defense Contracts.

DTIC Science & Technology

1984-06-01

a reduction in industry participation in the defense mobilization base, and a limiting of capital available for investment in producti- vity...FAR proposals, it appears that this stratgy has b-2n successful to a large degree. Thor,-, ar , how-vr, still areas where critics believe that further...appropriations. Lobbying includes but is not limited to personal discussions or conferences, advertising , sending tel- egrams, engaging in telephonic

A Critique of Sociocultural Values in PBIS.

PubMed

Wilson, Alyssa N

2015-05-01

Horner and Sugai provide lessons learned from their work with disseminating the Positive Behavioral Interventions and Support (PBIS) model. While PBIS represents an empirical school-wide approach for maladaptive student behaviors, the model appears to have limitations regarding sociocultural values and behavioral data collection practices. The current paper provides an overview of three identified areas for improvement and outlines how administrators using PBIS can incorporate acceptance and mindfulness-based intervention procedures to address the discussed limitations.

Current collection in an anisotropic plasma

NASA Technical Reports Server (NTRS)

Li, Wei-Wei

1990-01-01

A general method is given to derive the current-potential relations in anisotropic plasmas. Orbit limit current is assumed. The collector is a conductive sphere or an infinite cylinder. Any distribution which is an arbitrary function of the velocity vector can be considered as a superposition of many mono-energetic beams whose current-potential relations are known. The results for two typical pitch angle distributions are derived and discussed in detail. The general properties of the current potential relations are very similar to that of a Maxwellian plasma except for an effective temperature which varies with the angle between the magnetic field and the charging surface. The conclusions are meaningful to generalized geometries.

Discussing race-related limitations of genomic testing for colon cancer risk: implications for education and counseling.

PubMed

Butrick, Morgan N; Vanhusen, Lauren; Leventhal, Kara-Grace; Hooker, Gillian W; Nusbaum, Rachel; Peshkin, Beth N; Salehizadeh, Yasmin; Pavlick, Jessica; Schwartz, Marc D; Graves, Kristi D

2014-08-01

This study examines communication about limitations of genomic results interpretation for colon cancer risk during education and counseling of minority participants. As part of a larger study conducted from 2010 to 2012, participants recruited from a large primary care clinic were offered testing for a research panel of 3 genomic markers (single nucleotide polymorphisms or SNPs) for colorectal cancer risk. Genetic counselors conducted pre- and post-test sessions which included discussion of limitations of result interpretation due to the lack of racial/ethnic diversity in research populations from which risk data are derived. Sessions were audio-recorded, transcribed and thematically analyzed. Many participants did not respond directly to this limitation. Among the participants that responded directly to this race-related limitation, many responses were negative. However, a few participants connected the limited minority information about SNPs with the importance of their current research participation. Genetic counselor discussions of this limitation were biomedically focused with limited explanations for the lacking data. The communication process themes identified included: low immediacy (infrequent use of language directly involving a participant), verbal dominance (greater speaking ratio of the counselor to the patient) and wide variation in the degree of interactivity (or the amount of turn-taking during the discussion). Placed within the larger literature on patient-provider communication, these present results provide insight into the dynamics surrounding race-related educational content for genomic testing and other emerging technologies. Clinicians may be better able to engage patients in the use of new genomic technology by increasing their awareness of specific communication processes and patterns during education or counseling sessions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Physics of systematic frequency variations in hydrogen masers

NASA Technical Reports Server (NTRS)

Mattison, Edward M.

1990-01-01

The frequency stability of hydrogen masers for intervals longer that 10(exp 4) seconds is limited at present by systematic processes. Researchers discuss the physics of frequency-determining mechanisms internal to the maser that are susceptible to systematic variations, and the connections between these internal mechanisms and external environmental factors. Based upon estimates of the magnitudes of systematic effects, they find that the primary internal mechanisms currently limiting long-term maser frequency stability are cavity pulling, at the level parts in 10(exp 15) per day, and wall shift variations, at the level of parts in 10(exp 16) to parts in 10(exp 15) per day. They discuss strategies for reducing systematic frequency variations.

Physics of systematic frequency variations in hydrogen masers

NASA Technical Reports Server (NTRS)

Mattison, Edward M.

1992-01-01

The frequency stability of hydrogen masers for intervals longer than 10 exp 4 s is currently limited by systematic processes. The physics of frequency-determining mechanisms internal to the maser that are susceptible to systematic variations, and the connections between these internal mechanisms and external environmental factors are discussed. From estimates of the magnitudes of systematic effects, it is found that the primary internal mechanisms limiting long-term maser frequency stability are cavity pulling, at the level of parts in 1015 per day, and wall shift variations, at the level of parts in 10 exp 16 to parts in 10 exp 15 per day. Strategies for reducing systematic frequency variations are discussed.

HVI Ballistic Limit Characterization of Fused Silica Thermal Panes

NASA Technical Reports Server (NTRS)

Miller, J. E.; Bohl, W. D.; Christiansen, E. L.; Davis, B. A.; Deighton, K. D.

2015-01-01

Fused silica window systems are used heavily on crewed reentry vehicles, and they are currently being used on the next generation of US crewed spacecraft, Orion. These systems improve crew situational awareness and comfort, as well as, insulating the reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are highly exposed to space environment hazards like solid particle impacts. This paper discusses impact studies up to 10 km/s on a fused silica window system proposed for the Orion spacecraft. A ballistic limit equation that describes the threshold of perforation of a fuse silica pane over a broad range of impact velocities, obliquities and projectile materials is discussed here.

Clinical outcomes for patients with liver-limited metastatic colorectal cancer: Arguing the case for specialist hepatobiliary multidisciplinary assessment.

PubMed

Thillai, K; Repana, D; Korantzis, I; Kane, P; Prachalias, A; Ross, P

2016-09-01

In patients with liver-limited metastatic colorectal cancer, hepatic resection can offer a significant survival benefit over systemic therapy alone. Specialist hepatobiliary multidisciplinary meetings are currently believed to provide the best forum to discuss the management for these patients. A retrospective analysis was undertaken of patients diagnosed with liver-limited metastatic colorectal cancer over 6 months within a cancer network in the United Kingdom. In addition, patients who were diagnosed but not referred to the hepatobiliary meeting were discussed within a virtual multi-disciplinary setting. Contributors were blinded and proposed management recorded. 159 newly diagnosed patients with liver-limited metastatic colorectal cancer were identified. 68 (43%) were referred at initial diagnosis and 38 (24%) referred following systemic treatment. 35 (51%) who were discussed at baseline underwent a subsequent hepatectomy or radiofrequency ablation, as did 18 (47%) patients referred after chemotherapy. Of the remaining 53 (33%) patients not referred, imaging was available for 31 (58%). Decisions regarding potential liver-directed therapy were discussed within a multi-disciplinary setting. 13 (42%) were identified as resectable or potentially resectable and 11 (36%) may have been suitable for a clinical trial. In reality, none of these 31 patients (100%) underwent surgery or ablation. Whilst the majority of patients with liver-limited metastatic colorectal cancer were referred appropriately, this study demonstrates that a significant number with potentially resectable disease are not being discussed at specialist meetings. A review of all diagnosed cases would ensure that an increased number of patients are offered hepatic resection or ablation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Design and optimisation of low heat load liquid helium cryostat to house cryogenic current comparator in antiproton decelerator at CERN

NASA Astrophysics Data System (ADS)

Lees, A.; Koettig, T.; Fernandes, M.; Tan, J.

2017-02-01

The Cryogenic Current Comparator (CCC) is installed in the low-energy Antiproton Decelerator (AD) at CERN to make an absolute measurement of the beam intensity. Operating below 4.2 K, it is based on a superconducting quantum interference device (SQUID) and employs a superconducting niobium shield to supress magnetic field components not linked to the beam current. The AD contains no permanent cryogenic infrastructure so the local continuous liquefaction of helium using a pulse-tube is required; limiting the available cooling power to 0.69 W at 4.2K. Due to the sensitivity of the SQUID to variations in magnetic fields, the CCC is highly sensitive to mechanical vibration which is limited to a minimum by the support systems of the cryostat. This article presents the cooling system of the cryostat and discusses the design challenges overcome to minimise the transmission of vibration to the CCC while operating within the cryogenic limits imposed by the cooling system.

At the Crossroads of Nanotoxicology: Past Achievements and Current Challenges

DTIC Science & Technology

2015-01-01

rates of ionic dissolution, improving in vitro to in vivo predictive efficiencies, and establishing safety exposure limits. This Review will discuss...Oberdörster et al., 2005a), which drove the focus of in vitro and in vivo model selection to accommodate these areas of higher NM exposure. Most...Accordingly, a current challenge is the design of simple, in vitro models that reliably predict in vivo effects following a NM challenge. In order

Terahertz: the Far-Ir Challenge

NASA Astrophysics Data System (ADS)

Dispenza, Massimiliano; Fiorello, Annamaria; Secchi, Alberto; Varasi, Mauro

This chapter is an overview on terahertz technologies and applications for sensing. The most advanced imaging and spectroscopy techniques are described, considering current opportunities and limitations in comparison to probes in the adjacent regions of the e.m. spectrum. Potential applications are highlighted, with a specific focus on security for detection of illicit substances and revealing of hidden objects. The technological status and current bottlenecks on sources and detectors are reviewed and future trends discussed.

Current Collection in a Magnetic Field

NASA Technical Reports Server (NTRS)

Krivorutsky, E. N.

1997-01-01

It is found that the upper-bound limit for current collection in the case of strong magnetic field from the current is close to that given by the Parker-Murphy formula. This conclusion is consistent with the results obtained in laboratory experiments. This limit weakly depends on the shape of the wire. The adiabatic limit in this case will be easily surpassed due to strong magnetic field gradients near the separatrix. The calculations can be done using the kinetic equation in the drift approximation. Analytical results are obtained for the region where the Earth's magnetic field is dominant. The current collection can be calculated (neglecting scattering) using a particle simulation code. Dr. Singh has agreed to collaborate, allowing the use of his particle code. The code can be adapted for the case when the current magnetic field is strong. The needed dm for these modifications is 3-4 months. The analytical description and essential part of the program is prepared for the calculation of the current in the region where the adiabatic description can be used. This was completed with the collaboration of Drs. Khazanov and Liemohn. A scheme of measuring the end body position is also proposed. The scheme was discussed in the laboratory (with Dr. Stone) and it was concluded that it can be proposed for engineering analysis.

Immunologic Approaches for the Treatment of Multiple Myeloma

PubMed Central

Rasche, Leo; Weinhold, Niels; Morgan, Gareth J; van Rhee, Frits; Davies, Faith E

2017-01-01

The FDA approval of two monoclonal antibodies in 2015 has heralded a new era of targeted immunotherapies for multiple myeloma (MM). In this review we discuss the recent approaches using different immunological components to treat MM. In particular, we review current monoclonal antibody based therapies, engineered T- and NK cell products, ‘off-target’ immunomodulation, and strategies utilizing allogeneic cell transplantation in MM. We discuss how an immunologic approach offers promise for the treatment of this genetically heterogeneous disease, and how patients with acquired drug resistance may particularly benefit from these therapies. We also describe some of the limitations of the current strategies and speculate on the future of personalized immunotherapies for MM. PMID:28431262

New design and operating techniques and requirements for improved aircraft terminal area operations

NASA Technical Reports Server (NTRS)

Reeder, J. P.; Taylor, R. T.; Walsh, T. M.

1974-01-01

Current aircraft operating problems that must be alleviated for future high-density terminal areas are safety, dependence on weather, congestion, energy conservation, noise, and atmospheric pollution. The Microwave Landing System (MLS) under development by FAA provides increased capabilities over the current ILS. The development of the airborne system's capability to take maximum advantage of the MLS capabilities in order to solve terminal area problems are discussed. A major limiting factor in longitudinal spacing for capacity increase is the trailing vortex hazard. Promising methods for causing early dissipation of the vortices were explored. Flight procedures for avoiding the hazard were investigated. Terminal configured vehicles and their flight test development are discussed.

NASA Radiation Protection Research for Exploration Missions

NASA Technical Reports Server (NTRS)

Wilson, John W.; Cucinotta, Francis A.; Tripathi, Ram K.; Heinbockel, John H.; Tweed, John; Mertens, Christopher J.; Walker, Steve A.; Blattnig, Steven R.; Zeitlin, Cary J.

2006-01-01

The HZETRN code was used in recent trade studies for renewed lunar exploration and currently used in engineering development of the next generation of space vehicles, habitats, and EVA equipment. A new version of the HZETRN code capable of simulating high charge and energy (HZE) ions, light-ions and neutrons with either laboratory or space boundary conditions with enhanced neutron and light-ion propagation is under development. Atomic and nuclear model requirements to support that development will be discussed. Such engineering design codes require establishing validation processes using laboratory ion beams and space flight measurements in realistic geometries. We discuss limitations of code validation due to the currently available data and recommend priorities for new data sets.

Neurocognitive Processes and Pediatric Obesity Interventions: Review of Current Literature and Suggested Future Directions.

PubMed

Miller, Alison L

2016-06-01

Childhood obesity is a significant problem in the United States, but current childhood obesity prevention approaches have limited efficacy. Self-regulation processes organize behavior to achieve a goal and may shape health behaviors and health outcomes. Obesity prevention approaches that focus on the cognitive and behavioral mechanisms that underlie self-regulation early in life may therefore lead to better outcomes. This article reviews the development of executive functioning (EF), identifies influences on EF development, discusses aspects of EF relating to increased risk for childhood obesity, and considers how EF-weight associations may change across development. Implications for intervention are discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

Prevalence and Effects of Child Exposure to Domestic Violence.

ERIC Educational Resources Information Center

Fantuzzo, John W.; Mohr, Wanda K.

1999-01-01

Discusses the limitations of current databases documenting the prevalence and effects of child exposure to domestic violence and describes a model for the collection of reliable and valid prevalence data, the Spousal Assault Replication Program, which uses data collected by the police and university researchers. (SLD)

Theoretical Grounding: The "Missing Link" in Suicide Research.

ERIC Educational Resources Information Center

Rogers, James R.

2001-01-01

Discusses the strengths and limitations of the current pragmatic focus of research in suicidology and presents an argument for theoretical grounding as a precursor for continued advancement in this area. Presents an existential-constructivist framework of "meaning creation" as a theoretical heuristic for understanding suicide. Outlines general…

The Tunneling Microscope: A New Look at the Atomic World.

ERIC Educational Resources Information Center

Golovchenko, J. A.

1986-01-01

A new instrument called the tunneling microscope has recently been developed that is capable of generating real-space images of surfaces showing atomic structure. Discusses current capabilities, limitations, and the physics involved in the technique. Includes results from a study of silicon crystal surfaces. (JN)

Presidential Primaries: Front-Loaded Fiascoes?

ERIC Educational Resources Information Center

Gans, Curtis

1996-01-01

Criticizes the presidential primary process as possibly leading to the destruction of the two-party system. Claims that the current process limits the competition to the rich and famous, enhances the worst aspects of campaigning, and evaluates candidates purely on their political skills. Briefly discusses some reform proposals. (MJP)

Constructing Matching Texts in Two Languages: The Application of Propositional Analysis.

ERIC Educational Resources Information Center

Valdes, Guadalupe; And Others

1984-01-01

Discusses how current procedures for selecting/constructing equivalent texts may lead to error because of their specific limitations; proposes the utilization of micro-propositional analysis coupled with word-frequency lists and readability formulas for constructing "matching" texts; presents some procedures which researchers working in…

Estimating wildfire behavior and effects

Treesearch

Frank A. Albini

1976-01-01

This paper presents a brief survey of the research literature on wildfire behavior and effects and assembles formulae and graphical computation aids based on selected theoretical and empirical models. The uses of mathematical fire behavior models are discussed, and the general capabilities and limitations of currently available models are outlined.

Relevance and Retrieval Evaluation: Perspectives from Medicine.

ERIC Educational Resources Information Center

Hersh, William

1994-01-01

Discusses topical relevance and situational relevance, which takes into account the impact of the retrieval system on the user, in the context of medicine. Topics addressed include scientific validity; limitations of current evaluation methodology, including recall and precision; and a framework for future retrieval research based on an…

"Paideia," Then and Now.

ERIC Educational Resources Information Center

Keppel, Francis

1990-01-01

Discusses two widely practiced principles of management (protecting the rear and knowing the limits of a job) as they relate to the philosophy of education. The article examines Werner Jaeger's definition of education in his 1939 book, "Paideia," as well as other definitions that have helped shape current educational management. (SM)

Drug-disease interactions: narrative review of aspirin in gastric ulcer.

PubMed

Nwose, Ezekiel Uba; Yee, Kwang Choon

2016-09-01

Drug-disease interactions include the impact of a drug and a particular disease condition on each other. However, the current practice in addressing drug-disease interaction is unbalanced and mostly limited to how the drug worsens the disease or health condition. Aspirin and gastric ulcer interaction are used as an example to illustrate this concept, especially the narration of how disease affects drug efficacy. The number of molecules that make up 100 mg of aspirin is identified with a view to discuss the pharmacokinetics, especially in terms of absorption and distribution. Using hypothetical scenarios, the pharmacodynamics in co-morbidities that could involve gastric ulcer and aspirin are also discussed. There seems to be oversight in definition and description of drug-disease interaction, which is often limited to 'how drug exacerbates disease'. The implication of this limited definition is that the discussions, research and teaching of the topic either lacks information, or are not clear on 'how disease affects drug efficacy'. For example, gastric ulcer has the potential to enhance absorption, bioavailability and therapeutic effects of aspirin, but this is rarely discussed in preference to the probability of gastro-intestinal bleeding side-effect.

Environmental Barrier Coatings (EBC) for Ceramic Matrix Composite (CMC) Materials

NASA Technical Reports Server (NTRS)

Lee,Kang

2001-01-01

The upper use temperature of current Environmental Barrier Coatings (EBC's) based on mullite and BSAS (EPM EBC's) is limited to -255 F due to silica volatility, chemical reactions, and high thermal conductivity. Therefore, new EBC s having low CTE, good chemical compatibility, and high melting point (greater than 2700 F ) are being investigated. Sinter-resistant, low thermal conductivity EBC s are strongly desired to achieve the UEET EBC goal of 270 F EBC surface temperature and 30 F AT over long exposures (greater than 1000 hr). Key areas affecting the upper temperature limit of current EBC s as well as the ongoing efforts to develop next generation EBC s in the UEET Program will be discussed.

Skin appendage-derived stem cells: cell biology and potential for wound repair.

PubMed

Xie, Jiangfan; Yao, Bin; Han, Yutong; Huang, Sha; Fu, Xiaobing

2016-01-01

Stem cells residing in the epidermis and skin appendages are imperative for skin homeostasis and regeneration. These stem cells also participate in the repair of the epidermis after injuries, inducing restoration of tissue integrity and function of damaged tissue. Unlike epidermis-derived stem cells, comprehensive knowledge about skin appendage-derived stem cells remains limited. In this review, we summarize the current knowledge of skin appendage-derived stem cells, including their fundamental characteristics, their preferentially expressed biomarkers, and their potential contribution involved in wound repair. Finally, we will also discuss current strategies, future applications, and limitations of these stem cells, attempting to provide some perspectives on optimizing the available therapy in cutaneous repair and regeneration.

Search for time reversal invariance violation in neutron transmission

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

Bowman, J. David; Gudkov, Vladimir

2014-12-29

Time reversal invariance violating (TRIV) effects in neutron transmission through a nuclear target are discussed. Here, we demonstrate the existence of a class of experiments that are free from false asymmetries. We discuss the enhancement of TRIV effects for neutron energies corresponding to p-wave resonances in the compound nuclear system. Finaly, we analyze a model experiment and show that such tests can have a discovery potential of 10 2-10 4 compared to current limits.

Neutron Scattering and the 30 S Ribosomal Subunit of E. Coli

DOE R&D Accomplishments Database

Moore, P. B.; Engelman, D. M.; Langer, J. A.; Ramakrishnan, V. R.; Schindler, D. G.; Schoenborn, B. P.; Sillers, I. Y.; Yabuki, S.

1982-06-01

This paper reviews the progress made in the study of the internal organization of the 30 S ribosomal subunit of E. coli by neutron scattering since 1975. A map of that particle showing the position of 14 of the subunit's 21 proteins is presented, and the methods currently used for collecting and analyzing such data are discussed. Also discussed is the possibility of extending the interpretation of neutron mapping data beyond the limits practical today.

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

Stolterfoht, Martin; Armin, Ardalan; Pandey, Ajay K.

Photovoltaic performance in relation to charge transport is studied in efficient (7.6%) organic solar cells (PTB7:PC{sub 71}BM). Both electron and hole mobilities are experimentally measured in efficient solar cells using the resistance dependent photovoltage technique, while the inapplicability of classical techniques, such as space charge limited current and photogenerated charge extraction by linearly increasing voltage is discussed. Limits in the short-circuit current originate from optical losses, while charge transport is shown not to be a limiting process. Efficient charge extraction without recombination can be achieved with a mobility of charge carriers much lower than previously expected. The presence of dispersivemore » transport with strongly distributed mobilities in high efficiency solar cells is demonstrated. Reduced non-Langevin recombination is shown to be beneficial for solar cells with imbalanced, low, and dispersive electron and hole mobilities.« less

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

Dimastrogiovanni, Emanuela; Emami, Razieh, E-mail: emanuela1573@gmail.com, E-mail: iasraziehm@ust.hk

Probing correlations among short and long-wavelength cosmological fluctuations is known to be decisive for deepening the current understanding of inflation at the microphysical level. Spectral distortions of the CMB can be caused by dissipation of cosmological perturbations when they re-enter Hubble after inflation. Correlating spectral distortions with temperature anisotropies will thus provide the opportunity to greatly enlarge the range of scales over which squeezed limits can be tested, opening up a new window on inflation complementing the ones currently probed with CMB and LSS. In this paper we discuss a variety of inflationary mechanisms that can be efficiently constrained withmore » distortion-temperature correlations. For some of these realizations (representative of large classes of models) we derive quantitative predictions for the squeezed limit bispectra, finding that their amplitudes are above the sensitivity limits of an experiment such as the proposed PIXIE.« less

Advanced analytical modeling of double-gate Tunnel-FETs - A performance evaluation

NASA Astrophysics Data System (ADS)

Graef, Michael; Hosenfeld, Fabian; Horst, Fabian; Farokhnejad, Atieh; Hain, Franziska; Iñíguez, Benjamín; Kloes, Alexander

2018-03-01

The Tunnel-FET is one of the most promising devices to be the successor of the standard MOSFET due to its alternative current transport mechanism, which allows a smaller subthreshold slope than the physically limited 60 mV/dec of the MOSFET. Recently fabricated devices show smaller slopes already but mostly not over multiple decades of the current transfer characteristics. In this paper the performance limiting effects, occurring during the fabrication process of the device, such as doping profiles and midgap traps are analyzed by physics-based analytical models and their performance limiting abilities are determined. Additionally, performance enhancing possibilities, such as hetero-structures and ambipolarity improvements are introduced and discussed. An extensive double-gate n-Tunnel-FET model is presented, which meets the versatile device requirements and shows a good fit with TCAD simulations and measurement data.

Classification of radiation effects for dose limitation purposes: history, current situation and future prospects

PubMed Central

Hamada, Nobuyuki; Fujimichi, Yuki

2014-01-01

Radiation exposure causes cancer and non-cancer health effects, each of which differs greatly in the shape of the dose–response curve, latency, persistency, recurrence, curability, fatality and impact on quality of life. In recent decades, for dose limitation purposes, the International Commission on Radiological Protection has divided such diverse effects into tissue reactions (formerly termed non-stochastic and deterministic effects) and stochastic effects. On the one hand, effective dose limits aim to reduce the risks of stochastic effects (cancer/heritable effects) and are based on the detriment-adjusted nominal risk coefficients, assuming a linear-non-threshold dose response and a dose and dose rate effectiveness factor of 2. On the other hand, equivalent dose limits aim to avoid tissue reactions (vision-impairing cataracts and cosmetically unacceptable non-cancer skin changes) and are based on a threshold dose. However, the boundary between these two categories is becoming vague. Thus, we review the changes in radiation effect classification, dose limitation concepts, and the definition of detriment and threshold. Then, the current situation is overviewed focusing on (i) stochastic effects with a threshold, (ii) tissue reactions without a threshold, (iii) target organs/tissues for circulatory disease, (iv) dose levels for limitation of cancer risks vs prevention of non-life-threatening tissue reactions vs prevention of life-threatening tissue reactions, (v) mortality or incidence of thyroid cancer, and (vi) the detriment for tissue reactions. For future discussion, one approach is suggested that classifies radiation effects according to whether effects are life threatening, and radiobiological research needs are also briefly discussed. PMID:24794798

Present limits for the luminosity, the beam current and the beam lifetime in Doris II

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

Nesemann, H.; Sarau, B.

1985-10-01

The e e storage ring DORIS II has been operating for high energy physics experiments in the region of the Y resonances around 2x5 GeV and as a source for synchrotron radiation near 3.7 GeV. A luminosity of nearly 3x10T cm Ssec or more than 1500 (nb) /day has been achieved. For synchrotron radiation e -currents of about 100 mA are stored in 4 bunches (out of 480 buckets). As long as the beam-beam interaction does not limit the luminosity the optimum performance of the ring is obtained for both modes of operation if the currents stored are large, themore » cross section of the beam is small and the lifetime is long. Thus we concentrate the discussion on these subjects.« less

Pharmacotherapy of Essential Tremor

PubMed Central

Hedera, Peter; Cibulčík, František; Davis, Thomas L.

2013-01-01

Essential tremor (ET) is a common movement disorder but its pathogenesis remains poorly understood. This has limited the development of effective pharmacotherapy. The current therapeutic armamentaria for ET represent the product of careful clinical observation rather than targeted molecular modeling. Here we review their pharmacokinetics, metabolism, dosing, and adverse effect profiles and propose a treatment algorithm. We also discuss the concept of medically refractory tremor, as therapeutic trials should be limited unless invasive therapy is contraindicated or not desired by patients. PMID:24385718

Qualitative Approaches to Mixed Methods Practice

ERIC Educational Resources Information Center

Hesse-Biber, Sharlene

2010-01-01

This article discusses how methodological practices can shape and limit how mixed methods is practiced and makes visible the current methodological assumptions embedded in mixed methods practice that can shut down a range of social inquiry. The article argues that there is a "methodological orthodoxy" in how mixed methods is practiced…

Short-Term Home Visiting for Parents

ERIC Educational Resources Information Center

Cooley, Morgan

2011-01-01

The purpose of this article is to review various aspects of home-visiting programs that have shown to be effective in recent literature to inform policy makers, practitioners, and other involved stakeholders of the current best practices or limitations and to discuss future recommendations based on the literature. Areas of review include…

Passage Equivalency and Predictive Validity of Oral Reading Fluency Measures

ERIC Educational Resources Information Center

Checca, Christopher Jason

2012-01-01

The use of oral reading fluency (ORF) passages within a Response to Intervention (RTI) framework is examined. Significant limitations within the current ORF research are discussed. The passage equivalency and readability scores for DIBELS Next, AIMSweb, and a school district's curriculum's ORF passages are evaluated using Generalizability Theory…

Intercultural Education of Tolerance and Hospitality

ERIC Educational Resources Information Center

Dasli, Maria

2017-01-01

This paper aims to make a theoretical contribution to the current debate on intercultural education by focusing on the nature and limits of tolerance. Drawing on contemporary theorisations of the concept, it is suggested that while tolerance appears fundamental for confronting issues of difference, it has several caveats. The paper discusses the…

Justifying Music Instruction in American Public Schools: A Historical Perspective.

ERIC Educational Resources Information Center

Jorgensen, Estelle R.

1995-01-01

Charts the development of music education from early utilitarianism up to its current emphasis on aesthetic value. Recent attempts to pursue music education as an interdisciplinary subject have been limited due to budget cuts. Briefly discusses this financial crisis and suggests some sources of alternative funding. (MJP)

Policy options for reducing oil consumption and greenhouse gas emissions from the U.S. transportation sector

DOT National Transportation Integrated Search

2007-07-01

The goal of this discussion paper is to contribute to the current policy debate about how to effectively limit or reduce oil consumption and greenhouse-gas emissions from the U.S. transportation sector. The paper explains what is wrong with the statu...

Theaters in Elementary Schools. AIA School Plant Studies.

ERIC Educational Resources Information Center

Brush, Martha S.

1963-01-01

A national volunteer program for producing a children's theater in elementary schools is severaly limited by the inadequacy of theater facilities in local school systems. A general discussion of the theater program is presented, the current state of theater facilities in elementary schools, difficulties in play production, and possible causes for…

Proceedings of the Workshop on Improvements to Photometry

NASA Technical Reports Server (NTRS)

Borucki, W. J. (Editor); Young, A. T. (Editor)

1984-01-01

The purposes of the workshop were to determine what astronomical problems would benefit by increased photometric precision, determine the current level of precision, identify the processes limiting the precision, and recommend approaches to improving photometric precision. Twenty representatives of the university, industry, and government communities participated. Results and recommendations are discussed.

Statewide Education Databases: Policy Issues. Discussion Draft.

ERIC Educational Resources Information Center

Hansen, Kenneth H.

This essay reviews current policy issues regarding statewide educational databases. It begins by defining the major characteristics of a database and raising two questions: (1) Is it really necessary to have a statewide educational database? (2) What is the primary rationale for creating one? The limitations of databases in formulating educational…

Reflections and Future Prospects for Evaluation in Human Resource Development

ERIC Educational Resources Information Center

Han, Heeyoung; Boulay, David

2013-01-01

Human resource development (HRD) evaluation has often been criticized for its limited function in organizational decision making. This article reviews evaluation studies to uncover the current status of HRD evaluation literature. The authors further discuss general evaluation theories in terms of value, use, and evaluator role to extend the…

Progress in lattice gauge theory

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

Creutz, M.

1983-01-01

These lectures first provide an overview of the current status of lattice gauge theory calculations. They then review some technical points on group integration, gauge fixing, and order parameters. Various Monte Carlo algorithms are discussed. Finally, alternatives to the Wilson action are considered in the context of universality for the continuum limit. 41 references.

Taking Stock of Gender Reform Policies for Australian Schools: Past, Present and Future.

ERIC Educational Resources Information Center

Kenway, Jane

1997-01-01

Narrates 20 years of gender reform in Australian schools, including boys' education. Discusses the practices and processes of schools' gender reform work, indicating strengths and limitations. Identifies current contexts of gender reform, including the fields of educational policy and politics. Mentions larger cultural shifts affecting gender…

Computational Fluid Dynamics Technology for Hypersonic Applications

NASA Technical Reports Server (NTRS)

Gnoffo, Peter A.

2003-01-01

Several current challenges in computational fluid dynamics and aerothermodynamics for hypersonic vehicle applications are discussed. Example simulations are presented from code validation and code benchmarking efforts to illustrate capabilities and limitations. Opportunities to advance the state-of-art in algorithms, grid generation and adaptation, and code validation are identified. Highlights of diverse efforts to address these challenges are then discussed. One such effort to re-engineer and synthesize the existing analysis capability in LAURA, VULCAN, and FUN3D will provide context for these discussions. The critical (and evolving) role of agile software engineering practice in the capability enhancement process is also noted.

Spatial transformations: from fundamentals to applications.

PubMed

Foster, Robert; Grant, Patrick; Hao, Yang; Hibbins, Alastair; Philbin, Thomas; Sambles, Roy

2015-08-28

This paper forms the introduction to this themed issue of Philosophical Transactions of the Royal Society A on 'Spatial transformations', arising from the Royal Society Scientific Discussion Meeting held in January 2015. The paper begins with a review of the concepts and history of spatial transformations, followed by a discussion of the contributions from the papers in this themed issue. A summary of the advantages and current limitations of spatial transformations concludes the paper, with the key challenges identified at the Scientific Discussion Meeting also given. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Virtual reality, disability and rehabilitation.

PubMed

Wilson, P N; Foreman, N; Stanton, D

1997-06-01

Virtual reality, or virtual environment computer technology, generates simulated objects and events with which people can interact. Existing and potential applications for this technology in the field of disability and rehabilitation are discussed. The main benefits identified for disabled people are that they can engage in a range of activities in a simulator relatively free from the limitations imposed by their disability, and they can do so in safety. Evidence that the knowledge and skills acquired by disabled individuals in simulated environments can transfer to the real world is presented. In particular, spatial information and life skills learned in a virtual environment have been shown to transfer to the real world. Applications for visually impaired people are discussed, and the potential for medical interventions and the assessment and treatment of neurological damage are considered. Finally some current limitations of the technology, and ethical concerns in relation to disability, are discussed.

Current and Future Methods for Measuring Breast Density: A Brief Comparative Review

PubMed Central

Sak, Mark A.; Littrup, Peter J.; Duric, Neb; Mullooly, Maeve; Sherman, Mark E.; Gierach, Gretchen L.

2017-01-01

Breast density is one of the strongest predictors of breast cancer risk. Women with the densest breasts are 4 to 6 times more likely to develop cancer compared with those with the lowest densities. Breast density is generally assessed using mammographic imaging; however, this approach has limitations. Magnetic resonance imaging and ultrasound tomography are some alternative imaging modalities that can aid mammography in patient screening and the measurement of breast density. As breast density becomes more commonly discussed, knowledge of the advantages and limitations of breast density as a marker of risk will become more critical. This review article discusses the relationship between breast density and breast cancer risk, lists the benefits and drawbacks of using multiple different imaging modalities to measure density and briefly discusses how breast density will be applied to aid in breast cancer prevention and treatment. PMID:28943893

Compiling knowledge-based systems specified in KEE to Ada

NASA Technical Reports Server (NTRS)

Filman, Robert E.; Feldman, Roy D.

1991-01-01

The first year of the PrKAda project is recounted. The primary goal was to develop a system for delivering Artificial Intelligence applications developed in the ProKappa system in a pure-Ada environment. The following areas are discussed: the ProKappa core and ProTalk programming language; the current status of the implementation; the limitations and restrictions of the current system; and the development of Ada-language message handlers in the ProKappa environment.

Malaria on the Guiana Shield: a review of the situation in French Guiana

PubMed Central

Musset, Lise; Pelleau, Stéphane; Girod, Romain; Ardillon, Vanessa; Carvalho, Luisiane; Dusfour, Isabelle; Gomes, Margarete SM; Djossou, Félix; Legrand, Eric

2014-01-01

In a climate of growing concern that Plasmodium falciparum may be developing a drug resistance to artemisinin derivatives in the Guiana Shield, this review details our current knowledge of malaria and control strategy in one part of the Shield, French Guiana. Local epidemiology, test-treat-track strategy, the state of parasite drug resistance and vector control measures are summarised. Current issues in terms of mobile populations and legislative limitations are also discussed. PMID:25184998

The (non-)replicability of regulatory resource depletion: A field report employing non-invasive brain stimulation

PubMed Central

Martijn, Carolien; Alberts, Hugo J. E. M.; Thomson, Alix C.; David, Bastian; Kessler, Daniel

2017-01-01

Cognitive effort and self-control are exhausting. Although evidence is ambiguous, behavioural studies have repeatedly suggested that control-demanding tasks seem to deplete a limited cache of self-regulatory resources leading to performance degradations and fatigue. While resource depletion has indirectly been associated with a decline in right prefrontal cortex capacity, its precise neural underpinnings have not yet been revealed. This study consisted of two independent experiments, which set out to investigate the causal role of the right dorsolateral prefrontal cortex (DLPFC) in a classic dual phase depletion paradigm employing non-invasive brain stimulation. In Experiment 1 we demonstrated a general depletion effect, which was significantly eliminated by anodal transcranial Direct Current Stimulation to the right DLPFC. In Experiment 2, however, we failed to replicate the basic psychological depletion effect within a second independent sample. The dissimilar results are discussed in the context of the current ‘replication crisis’ and suggestions for future studies are offered. While our current results do not allow us to firmly argue for or against the existence of resource depletion, we outline why it is crucial to further clarify which specific external and internal circumstances lead to limited replicability of the described effect. We showcase and discuss the current inter-lab replication problem based on two independent samples tested within one research group (intra-lab). PMID:28362843

Improving antiretroviral therapy adherence in resource-limited settings at scale: a discussion of interventions and recommendations.

PubMed

Haberer, Jessica E; Sabin, Lora; Amico, K Rivet; Orrell, Catherine; Galárraga, Omar; Tsai, Alexander C; Vreeman, Rachel C; Wilson, Ira; Sam-Agudu, Nadia A; Blaschke, Terrence F; Vrijens, Bernard; Mellins, Claude A; Remien, Robert H; Weiser, Sheri D; Lowenthal, Elizabeth; Stirratt, Michael J; Sow, Papa Salif; Thomas, Bruce; Ford, Nathan; Mills, Edward; Lester, Richard; Nachega, Jean B; Bwana, Bosco Mwebesa; Ssewamala, Fred; Mbuagbaw, Lawrence; Munderi, Paula; Geng, Elvin; Bangsberg, David R

2017-01-01

Introduction : Successful population-level antiretroviral therapy (ART) adherence will be necessary to realize both the clinical and prevention benefits of antiretroviral scale-up and, ultimately, the end of AIDS. Although many people living with HIV are adhering well, others struggle and most are likely to experience challenges in adherence that may threaten virologic suppression at some point during lifelong therapy. Despite the importance of ART adherence, supportive interventions have generally not been implemented at scale. The objective of this review is to summarize the recommendations of clinical, research, and public health experts for scalable ART adherence interventions in resource-limited settings. Methods : In July 2015, the Bill and Melinda Gates Foundation convened a meeting to discuss the most promising ART adherence interventions for use at scale in resource-limited settings. This article summarizes that discussion with recent updates. It is not a systematic review, but rather provides practical considerations for programme implementation based on evidence from individual studies, systematic reviews, meta-analyses, and the World Health Organization Consolidated Guidelines for HIV, which include evidence from randomized controlled trials in low- and middle-income countries. Interventions are categorized broadly as education and counselling; information and communication technology-enhanced solutions; healthcare delivery restructuring; and economic incentives and social protection interventions. Each category is discussed, including descriptions of interventions, current evidence for effectiveness, and what appears promising for the near future. Approaches to intervention implementation and impact assessment are then described. Results and discussion : The evidence base is promising for currently available, effective, and scalable ART adherence interventions for resource-limited settings. Numerous interventions build on existing health care infrastructure and leverage available resources. Those most widely studied and implemented to date involve peer counselling, adherence clubs, and short message service (SMS). Many additional interventions could have an important impact on ART adherence with further development, including standardized counselling through multi-media technology, electronic dose monitoring, decentralized and differentiated models of care, and livelihood interventions. Optimal targeting and tailoring of interventions will require improved adherence measurement. Conclusions : The opportunity exists today to address and resolve many of the challenges to effective ART adherence, so that they do not limit the potential of ART to help bring about the end of AIDS.

Applying Definitions of “Asbestos” to Environmental and “Low-Dose” Exposure Levels and Health Effects, Particularly Malignant Mesothelioma

PubMed Central

Case, B. W.; Abraham, J. L.; Meeker, G.; Pooley, F. D.; Pinkerton, K. E.

2011-01-01

Although asbestos research has been ongoing for decades, this increased knowledge has not led to consensus in many areas of the field. Two such areas of controversy include the specific definitions of asbestos, and limitations in understanding exposure-response relationships for various asbestos types and exposure levels and disease. This document reviews the current regulatory and mineralogical definitions and how variability in these definitions has led to difficulties in the discussion and comparison of both experimental laboratory and human epidemiological studies for asbestos. This review also examines the issues of exposure measurement in both animal and human studies, and discusses the impact of these issues on determination of cause for asbestos-related diseases. Limitations include the lack of detailed characterization and limited quantification of the fibers in most studies. Associated data gaps and research needs are also enumerated in this review. PMID:21534084

Applying definitions of “asbestos” to environmental and “low-dose” exposure Levels and health effects, particularly malignant mesothelioma

USGS Publications Warehouse

Case, B.W.; Abraham, J.L.; Meeker, G.; Pooley, F.D.; Pinkerton, K.E.

2011-01-01

Although asbestos research has been ongoing for decades, this increased knowledge has not led to consensus in many areas of the field. Two such areas of controversy include the specific definitions of asbestos, and limitations in understanding exposure-response relationships for various asbestos types and exposure levels and disease. This document reviews the current regulatory and mineralogical definitions and how variability in these definitions has led to difficulties in the discussion and comparison of both experimental laboratory and human epidemiological studies for asbestos. This review also examines the issues of exposure measurement in both animal and human studies, and discusses the impact of these issues on determination of cause for asbestos-related diseases. Limitations include the lack of detailed characterization and limited quantification of the fibers in most studies. Associated data gaps and research needs are also enumerated in this review.

Towards reconstitution of membrane fusion mediated by SNAREs and other synaptic proteins

PubMed Central

Brunger, Axel T.; Cipriano, Daniel J.; Diao, Jiajie

2015-01-01

Abstract Proteoliposomes have been widely used for in vitro studies of membrane fusion mediated by synaptic proteins. Initially, such studies were made with large unsynchronized ensembles of vesicles. Such ensemble assays limited the insights into the SNARE-mediated fusion mechanism that could be obtained from them. Single particle microscopy experiments can alleviate many of these limitations but they pose significant technical challenges. Here we summarize various approaches that have enabled studies of fusion mediated by SNAREs and other synaptic proteins at a single-particle level. Currently available methods are described and their advantages and limitations are discussed. PMID:25788028

Review of modern double beta decay experiments

NASA Astrophysics Data System (ADS)

Barabash, A. S.

2015-10-01

The review of modern experiments on search and studying of double beta decay processes is done. Results of the most sensitive current experiments are discussed. The main attention is paid to EXO-200, KamLAND-Zen, GERDA-I and CUORE-0 experiments. Modern values of T1/2(2ν) and best present limits on neutrinoless double beta decay and double beta decay with Majoron emission are presented. Conservative limits on effective mass of a Majorana neutrino ( < 0.46 eV) and a coupling constant of Majoron to neutrino ( < 1.3 . 10-5) are obtained. Prospects of search for neutrinoless double beta decay in new experiments with sensitivity to at the level of ˜ 0.01-0.1 eV are discussed.

Helicopter noise regulations: An industry perspective

NASA Technical Reports Server (NTRS)

Wagner, R. A.

1978-01-01

A review of helicopter noise measurement programs and noise reduction/economic studies of FAA is given along with a critique of a study which addresses the economic impact of noise reduction on helicopter noise. Modification of several helicopters to reduce noise and demonstrate the economic impact of the application of the current state-of-the-art technology is discussed. Specific helicopters described include Boeing Vertol 347 Helicopter, Hughes OH-6 Helicopter, and Hughes 269C Helicopter. Other topics covered include: (1) noise trends and possible noise limits; (2) accuracy of helicopter noise prediction techniques; (3) limited change possibilities of derivatives; and (4) rotor impulsive noise. The unique operational capabilities of helicopters and the implications relative to noise regulations and certification are discussed.

Variational principle for scattering of light by dielectric particles

NASA Technical Reports Server (NTRS)

Yung, Y. L.

1978-01-01

Consideration is given to the work of Purcell and Pennypacker (1973) where a dielectric particle is taken to be an aggregate of N polarizable elements mounted on a cubic lattice. The simultaneous equations which result from the scattering problem are presented. This theory has been discussed in the case of nonspherical and inhomogeneous objects whose dimensions are smaller than or comparable to the wavelength of incident light. A more precise numerical treatment is derived for further progress. The variational principle is invoked and the practical limit for the current version of the scheme is a dipole array on the order of 10,000 atoms. Limits to the scattering parameter due to the phase difference between neighboring atoms are discussed.

Perspectives of shaped pulses for EPR spectroscopy

NASA Astrophysics Data System (ADS)

Spindler, Philipp E.; Schöps, Philipp; Kallies, Wolfgang; Glaser, Steffen J.; Prisner, Thomas F.

2017-07-01

This article describes current uses of shaped pulses, generated by an arbitrary waveform generator, in the field of EPR spectroscopy. We show applications of sech/tanh and WURST pulses to dipolar spectroscopy, including new pulse schemes and procedures, and discuss the more general concept of optimum-control-based pulses for applications in EPR spectroscopy. The article also describes a procedure to correct for experimental imperfections, mostly introduced by the microwave resonator, and discusses further potential applications and limitations of such pulses.

Diffusion Weighted/Tensor Imaging, Functional MRI and Perfusion Weighted Imaging in Glioblastoma-Foundations and Future.

PubMed

Salama, Gayle R; Heier, Linda A; Patel, Praneil; Ramakrishna, Rohan; Magge, Rajiv; Tsiouris, Apostolos John

2017-01-01

In this article, we review the basics of diffusion tensor imaging and functional MRI, their current utility in preoperative neurosurgical mapping, and their limitations. We also discuss potential future applications, including implementation of resting state functional MRI. We then discuss perfusion and diffusion-weighted imaging and their application in advanced neuro-oncologic practice. We explain how these modalities can be helpful in guiding surgical biopsies and differentiating recurrent tumor from treatment related changes.

Diffusion Weighted/Tensor Imaging, Functional MRI and Perfusion Weighted Imaging in Glioblastoma—Foundations and Future

PubMed Central

Salama, Gayle R.; Heier, Linda A.; Patel, Praneil; Ramakrishna, Rohan; Magge, Rajiv; Tsiouris, Apostolos John

2018-01-01

In this article, we review the basics of diffusion tensor imaging and functional MRI, their current utility in preoperative neurosurgical mapping, and their limitations. We also discuss potential future applications, including implementation of resting state functional MRI. We then discuss perfusion and diffusion-weighted imaging and their application in advanced neuro-oncologic practice. We explain how these modalities can be helpful in guiding surgical biopsies and differentiating recurrent tumor from treatment related changes. PMID:29403420

Status of commercial fuel cell powerplant system development

NASA Technical Reports Server (NTRS)

Warshay, Marvin

1987-01-01

The primary focus is on the development of commercial Phosphoric Acid Fuel Cell (PAFC) powerplant systems because the PAFC, which has undergone extensive development, is currently the closest fuel cell system to commercialization. Shorter discussions are included on the high temperature fuel cell systems which are not as mature in their development, such as the Molten Carbonate Fuel Cell (MCFC) and the Solid Oxide Fuel Cell (SOFC). The alkaline and the Solid Polymer Electrolyte (SPE) fuel cell systems, are also included, but their discussions are limited to their prospects for commercial development. Currently, although the alkaline fuel cell continues to be used for important space applications there are no commercial development programs of significant size in the USA and only small efforts outside. The market place for fuel cells and the status of fuel cell programs in the USA receive extensive treatment. The fuel cell efforts outside the USA, especially the large Japanese programs, are also discussed.

Exploring the science of thinking independently together: Faraday Discussion Volume 204 - Complex Molecular Surfaces and Interfaces, Sheffield, UK, July 2017.

PubMed

Samperi, M; Hirsch, B E; Diaz Fernandez, Y A

2017-11-23

The 2017 Faraday Discussion on Complex Molecular Surfaces and Interfaces brought together theoreticians and experimentalists from both physical and chemical backgrounds to discuss the relevant applied and fundamental research topics within the broader field of chemical surface analysis and characterization. Main discussion topics from the meeting included the importance of "disordered" two-dimensional (2D) molecular structures and the utility of kinetically trapped states. An emerging need for new experimental tools to address dynamics and kinetic pathways involved in self-assembled systems, as well as the future prospects and current limitations of in silico studies were also discussed. The following article provides a brief overview of the work presented and the challenges discussed during the meeting.

Application Study of a High Temperature Superconducting Fault Current Limiter for Electric Power System

NASA Astrophysics Data System (ADS)

Naito, Yuji; Shimizu, Iwao; Yamaguchi, Iwao; Kaiho, Katsuyuki; Yanabu, Satoru

Using high temperature superconductor, a Superconducting Fault Current Limiter (SFCL) was made and tested. Superconductor and vacuum interrupter as commutation switch are connected in parallel with bypass coil. When a fault occurs and the excessive current flows, superconductor is first quenched and the current is transferred to bypass coil because on voltage drop of superconductor. At the same time, since magnetic field is generated by current which flows in bypass coil, commutation switch is immediately driven by electromagnetic repulsion plate connected to driving rod of vacuum interrupter, and superconductor is separated from this circuit. Using the testing model, we could separate the superconductor from a circuit due to movement of vacuum interrupter within half-cycle current and transfer all current to bypass coil. Since operation of a commutation switch is included in current limiting operation of this testing model, it is one of helpful circuit of development of SFCL in the future. Moreover, since it can make the consumed energy of superconductor small during fault state due to realization of high-speed switch with simple composition, the burden of superconductor is reduced compared with conventional resistive type SFCL and it is considered that the flexibility of a SFCL design increases. Cooperation with a circuit breaker was also considered, the trial calculation of a parameter and energy of operation is conducted and discussion in the case of installing the SFCL to electric power system is made.

A gas-kinetic BGK scheme for the compressible Navier-Stokes equations

NASA Technical Reports Server (NTRS)

Xu, Kun

2000-01-01

This paper presents an improved gas-kinetic scheme based on the Bhatnagar-Gross-Krook (BGK) model for the compressible Navier-Stokes equations. The current method extends the previous gas-kinetic Navier-Stokes solver developed by Xu and Prendergast by implementing a general nonequilibrium state to represent the gas distribution function at the beginning of each time step. As a result, the requirement in the previous scheme, such as the particle collision time being less than the time step for the validity of the BGK Navier-Stokes solution, is removed. Therefore, the applicable regime of the current method is much enlarged and the Navier-Stokes solution can be obtained accurately regardless of the ratio between the collision time and the time step. The gas-kinetic Navier-Stokes solver developed by Chou and Baganoff is the limiting case of the current method, and it is valid only under such a limiting condition. Also, in this paper, the appropriate implementation of boundary condition for the kinetic scheme, different kinetic limiting cases, and the Prandtl number fix are presented. The connection among artificial dissipative central schemes, Godunov-type schemes, and the gas-kinetic BGK method is discussed. Many numerical tests are included to validate the current method.

Seismic refraction analysis: the path forward

USGS Publications Warehouse

Haines, Seth S.; Zelt, Colin; Doll, William

2012-01-01

Seismic Refraction Methods: Unleashing the Potential and Understanding the Limitations; Tucson, Arizona, 29 March 2012 A workshop focused on seismic refraction methods took place on 29 May 2012, associated with the 2012 Symposium on the Application of Geophysics to Engineering and Environmental Problems. This workshop was convened to assess the current state of the science and discuss paths forward, with a primary focus on near-surface problems but with an eye on all applications. The agenda included talks on these topics from a number of experts interspersed with discussion and a dedicated discussion period to finish the day. Discussion proved lively at times, and workshop participants delved into many topics central to seismic refraction work.

Pacemakers and implantable cardioverter-defibrillators in pediatric patients.

PubMed

Silka, Michael J; Bar-Cohen, Yaniv

2006-11-01

The use of pacemakers and implantable cardioverter-defibrillators (ICDs) in infants, children, and patients with congenital heart disease presents unique challenges and considerations. They include uncommon indications for device implantation, innovative approaches to lead implantation and configuration, and age-dependent and disease-specific aspects of device programming. In this review, the current indications for pacemaker and ICD implantation in young patients are discussed, followed by consideration of the approaches to lead and device placement in very small patients and those with complex congenital heart disease, in whom unique problems may be encountered. The limitations of programmability of current pacemakers and ICDs when used in young patients are discussed, followed by an analysis of long-term device follow-up and potential late complications.

Internal kinematics and dynamical models of dwarf spheroidal galaxies around the Milky Way

NASA Astrophysics Data System (ADS)

Battaglia, Giuseppina; Helmi, Amina; Breddels, Maarten

2013-09-01

We review our current understanding of the internal dynamical properties of the dwarf spheroidal galaxies surrounding the Milky Way. These are the most dark matter dominated galaxies, and as such may be considered ideal laboratories to test the current concordance cosmological model, and in particular provide constraints on the nature of the dominant form of dark matter. We discuss the latest observations of the kinematics of stars in these systems, and how these may be used to derive their mass distribution. We tour through the various dynamical techniques used, with emphasis on the complementarity and limitations, and discuss what the results imply also in the context of cosmological models. Finally we provide an outlook on exciting developments in this field.

Targeting activator protein 1 signaling pathway by bioactive natural agents: Possible therapeutic strategy for cancer prevention and intervention.

PubMed

Tewari, Devesh; Nabavi, Seyed Fazel; Nabavi, Seyed Mohammad; Sureda, Antoni; Farooqi, Ammad Ahmad; Atanasov, Atanas G; Vacca, Rosa Anna; Sethi, Gautam; Bishayee, Anupam

2018-02-01

Activator protein 1 (AP-1) is a key transcription factor in the control of several cellular processes responsible for cell survival proliferation and differentiation. Dysfunctional AP-1 expression and activity are involved in several severe diseases, especially inflammatory disorders and cancer. Therefore, targeting AP-1 has recently emerged as an attractive therapeutic strategy for cancer prevention and therapy. This review summarizes our current understanding of AP-1 biology and function as well as explores and discusses several natural bioactive compounds modulating AP-1-associated signaling pathways for cancer prevention and intervention. Current limitations, challenges, and future directions of research are also critically discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

The promise and challenge of virtual gaming technologies for chronic pain: the case of graded exposure for low back pain.

PubMed

Trost, Zina; Zielke, Marjorie; Guck, Adam; Nowlin, Liza; Zakhidov, Djanhangir; France, Christopher R; Keefe, Francis

2015-01-01

Virtual reality (VR) technologies have been successfully applied to acute pain interventions and recent reviews have suggested their potential utility in chronic pain. The current review highlights the specific relevance of VR interactive gaming technologies for pain-specific intervention, including their current use across a variety of physical conditions. Using the example of graded-exposure treatment for pain-related fear and disability in chronic low back pain, we discuss ways that VR gaming can be harnessed to optimize existing chronic pain therapies and examine the potential limitations of traditional VR interfaces in the context of chronic pain. We conclude by discussing directions for future research on VR-mediated applications in chronic pain.

Regulatory perspectives on acceptability testing of dosage forms in children.

PubMed

Kozarewicz, Piotr

2014-08-05

Current knowledge about the age-appropriateness of different dosage forms is still fragmented or limited. Applicants are asked to demonstrate that the target age group(s) can manage the dosage form or propose an alternative strategy. However, questions remain about how far the applicant must go and what percentage of patients must find the strategy 'acceptable'. The aim of this overview is to provide an update on current thinking and understanding of the problem, and discuss issues relating to the acceptability testing. This overview should be considered as means to start a wider discussion which hopefully will result in a harmonised, globally acceptable approach for confirmation of the acceptability in the future. Copyright © 2014 Elsevier B.V. All rights reserved.

Vaccines: From Empirical Development to Rational Design

PubMed Central

Rueckert, Christine; Guzmán, Carlos A.

2012-01-01

Infectious diseases are responsible for an overwhelming number of deaths worldwide and their clinical management is often hampered by the emergence of multi-drug-resistant strains. Therefore, prevention through vaccination currently represents the best course of action to combat them. However, immune escape and evasion by pathogens often render vaccine development difficult. Furthermore, most currently available vaccines were empirically designed. In this review, we discuss why rational design of vaccines is not only desirable but also necessary. We introduce recent developments towards specifically tailored antigens, adjuvants, and delivery systems, and discuss the methodological gaps and lack of knowledge still hampering true rational vaccine design. Finally, we address the potential and limitations of different strategies and technologies for advancing vaccine development. PMID:23144616

Advanced 3-V semiconductor technology assessment

NASA Technical Reports Server (NTRS)

Nowogrodzki, M.

1983-01-01

Components required for extensions of currently planned space communications systems are discussed for large antennas, crosslink systems, single sideband systems, Aerostat systems, and digital signal processing. Systems using advanced modulation concepts and new concepts in communications satellites are included. The current status and trends in materials technology are examined with emphasis on bulk growth of semi-insulating GaAs and InP, epitaxial growth, and ion implantation. Microwave solid state discrete active devices, multigigabit rate GaAs digital integrated circuits, microwave integrated circuits, and the exploratory development of GaInAs devices, heterojunction devices, and quasi-ballistic devices is considered. Competing technologies such as RF power generation, filter structures, and microwave circuit fabrication are discussed. The fundamental limits of semiconductor devices and problems in implementation are explored.

Mesenchymal Stem Cells for Osteochondral Tissue Engineering

PubMed Central

Ng, Johnathan; Bernhard, Jonathan; Vunjak-Novakovic, Gordana

2017-01-01

Summary Mesenchymal stem cells (MSC) are of major interest to regenerative medicine, because of the ease of harvesting from a variety of sources (including bone marrow and fat aspirates) and ability to form a range of mesenchymal tissues, in vitro and in vivo. We focus here on the use of MSCs for engineering of cartilage, bone, and complex osteochondral tissue constructs, using protocols that replicate some aspects of the natural mesodermal development. For engineering of human bone, we discuss some of the current advances, and highlight the use of perfusion bioreactors for supporting anatomically exact human bone grafts. For engineering of human cartilage, we discuss limitations of current approaches, and highlight engineering of stratified, mechanically functional human cartilage interfaced with bone by mesenchymal condensation of MSCs. Taken together, the current advances enable engineering physiologically relevant bone, cartilage and osteochondral composites, and physiologically relevant studies of osteochondral development and disease. PMID:27236665

Current perspectives and challenges in understanding the role of nitrite as an integral player in nitric oxide biology and therapy

PubMed Central

Vitturi, Dario A.; Patel, Rakesh P.

2011-01-01

Beyond an inert oxidation product of nitric oxide (NO) metabolism, current thinking posits a key role for nitrite as a mediator of NO-signaling, especially during hypoxia. This concept has been discussed both in the context of nitrite serving a role as an endogenous modulator of NO-homeostasis, but also from a novel clinical perspective whereby nitrite therapy may replete NO-signaling and prevent ischemic tissue injury. Indeed, the relatively rapid translation of studies delineating mechanisms of action to ongoing and planned clinical trials has been critical in fuelling interest in nitrite biology and several excellent reviews have been written on this topic. In this article we limit our discussions to current concepts, and what we feel are questions that remain unanswered within the paradigm of nitrite being a mediator of NO biology. PMID:21683783

The Development and Clinical Evaluation of Second-Generation Leishmaniasis Vaccines

PubMed Central

Duthie, Malcolm S.; Raman, Vanitha S.; Piazza, Franco M.; Reed, Steven G.

2011-01-01

Infection with Leishmania parasites results in a range of clinical manifestations and outcomes. Control of Leishmania parasite transmission is extremely difficult due to the large number of vectors and potential reservoirs, and none of the current treatments are ideal. Vaccination could be an effective strategy to provide sustained control. In this review, the current global situation with regard to leishmaniasis, the immunology of Leishmania infection and various efforts to identify second generation vaccine candidates are briefly discussed. The variety of clinical trials conducted using the only current second generation vaccine approved for clinical use, LEISH-F1 + MPL-SE, are described. Given that epidemiological evidence suggests that reducing the canine reservoir also positively impacts human incidence, efforts at providing a vaccine for leishmaniasis in dogs are highlighted. Finally, potential refinements and surrogate markers that could expedite the introduction of a vaccine that can limit the severity and incidence of leishmaniasis are discussed. PMID:22085553

Is ginger beneficial for nausea and vomiting? An update of the literature.

PubMed

Marx, Wolfgang; Kiss, Nicole; Isenring, Liz

2015-06-01

Nausea and vomiting can pose a significant burden to patients in a variety of clinical settings. Previous evidence suggests that ginger may be an effective treatment for these symptoms; however, current evidence has been mixed. This article discusses recent clinical trials that have investigated ginger as a treatment for multiple types of nausea and vomiting. In addition, the potential mechanisms of action of ginger will be discussed. This article identified nine studies and seven reviews that investigated ginger for morning sickness, postoperative nausea and vomiting, chemotherapy-induced, and antiretroviral-induced nausea and vomiting. All studies reported that ginger provided a significant reduction in nausea and vomiting; however, the clinical relevance of some studies is less certain. Common limitations within the literature include the lack of standardized extracts, poorly controlled or blinded studies, and limited sample size. In addition, recent evidence has provided further support for 5-HT3 receptor antagonism as a mechanism by which ginger may exert its potentially beneficial effect on nausea and vomiting. The results of studies in this article suggest that ginger is a promising treatment for nausea and vomiting in a variety of clinical settings and possesses a clinically relevant mechanism. However, further studies are required to address the limitations in the current clinical literature before firm recommendations for its use can be made.

The Race To X-ray Microbeam and Nanobeam Science

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

Ice, Gene E; Budai, John D; Pang, Judy

2011-01-01

X-ray microbeams are an emerging characterization tool with transformational implications for broad areas of science ranging from materials structure and dynamics, geophysics and environmental science to biophysics and protein crystallography. In this review, we discuss the race toward sub-10 nm- x-ray beams with the ability to penetrate tens to hundreds of microns into most materials and with the ability to determine local (crystal) structure. Examples of science enabled by current micro/nanobeam technologies are presented and we provide a perspective on future directions. Applications highlighted are chosen to illustrate the important features of various submicron beam strategies and to highlight themore » directions of current and future research. While it is clear that x-ray microprobes will impact science broadly, the practical limit for hard x-ray beam size, the limit to trace element sensitivity, and the ultimate limitations associated with near-atomic structure determinations are the subject of ongoing research.« less

Limits to Open Class Performance?

NASA Technical Reports Server (NTRS)

Bowers, Albion H.

2008-01-01

This presentation discusses open or unlimited class aircraft performance limitations and design solutions. Limitations in this class of aircraft include slow climbing flight which requires low wing loading, high cruise speed which requires high wing loading, gains in induced or viscous drag alone which result in only half the gain overall and other structural problems (yaw inertia and spins, flutter and static loads integrity). Design solutions include introducing minimum induced drag for a given span (elliptical span load or winglets) and introducing minimum induced drag for a bell shaped span load. It is concluded that open class performance limits (under current rules and technologies) is very close to absolute limits, though some gains remain to be made from unexplored areas and new technologies.

Meaningful Peer Review in Radiology: A Review of Current Practices and Potential Future Directions.

PubMed

Moriarity, Andrew K; Hawkins, C Matthew; Geis, J Raymond; Dreyer, Keith J; Kamer, Aaron P; Khandheria, Paras; Morey, Jose; Whitfill, James; Wiggins, Richard H; Itri, Jason N

2016-12-01

The current practice of peer review within radiology is well developed and widely implemented compared with other medical specialties. However, there are many factors that limit current peer review practices from reducing diagnostic errors and improving patient care. The development of "meaningful peer review" requires a transition away from compliance toward quality improvement, whereby the information and insights gained facilitate education and drive systematic improvements that reduce the frequency and impact of diagnostic error. The next generation of peer review requires significant improvements in IT functionality and integration, enabling features such as anonymization, adjudication by multiple specialists, categorization and analysis of errors, tracking, feedback, and easy export into teaching files and other media that require strong partnerships with vendors. In this article, the authors assess various peer review practices, with focused discussion on current limitations and future needs for meaningful peer review in radiology. Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.

Noninvasive Brain Stimulation in Pediatric Attention-Deficit Hyperactivity Disorder (ADHD): A Review.

PubMed

Rubio, Belen; Boes, Aaron D; Laganiere, Simon; Rotenberg, Alexander; Jeurissen, Danique; Pascual-Leone, Alvaro

2016-05-01

Attention-deficit hyperactivity disorder (ADHD) is one of the most prevalent neurodevelopmental disorders in the pediatric population. The clinical management of ADHD is currently limited by a lack of reliable diagnostic biomarkers and inadequate therapy for a minority of patients who do not respond to standard pharmacotherapy. There is optimism that noninvasive brain stimulation may help to address these limitations. Transcranial magnetic stimulation and transcranial direct current stimulation are 2 methods of noninvasive brain stimulation that modulate cortical excitability and brain network activity. Transcranial magnetic stimulation can be used diagnostically to probe cortical neurophysiology, whereas daily use of repetitive transcranial magnetic stimulation or transcranial direct current stimulation can induce long-lasting and potentially therapeutic changes in targeted networks. In this review, we highlight research showing the potential diagnostic and therapeutic applications of transcranial magnetic stimulation and transcranial direct current stimulation in pediatric ADHD. We also discuss the safety and ethics of using these tools in the pediatric population. © The Author(s) 2015.

A paradigm shift on beta-thalassaemia treatment: How will we manage this old disease with new therapies?

PubMed

Cappellini, Maria Domenica; Porter, John B; Viprakasit, Vip; Taher, Ali T

2018-07-01

Beta-thalassaemia causes defective haemoglobin synthesis leading to ineffective erythropoiesis, chronic haemolytic anaemia, and subsequent clinical complications. Blood transfusion and iron chelation allow long-term disease control, and haematopoietic stem cell transplantation offers a potential cure for some patients. Nonetheless, there are still many challenges in the management of beta-thalassaemia. The main treatment option for most patients is supportive care; furthermore, the long-term efficacy and safety of current therapeutic strategies are limited and adherence is suboptimal. An increasing understanding of the underlying molecular and cellular disease mechanisms plus an awareness of limitations of current management strategies are driving research into novel therapeutic options. Here we provide an overview of the current pathophysiology, clinical manifestations, and global burden of beta-thalassaemia. We reflect on what has been achieved to date, describe the challenges associated with currently available therapy, and discuss how these issues might be addressed by novel therapeutic approaches in development. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Gene therapy for arthritis

PubMed Central

Traister, Russell S.

2008-01-01

Arthritis is among the leading causes of disability in the developed world. There remains no cure for this disease and the current treatments are only modestly effective at slowing the disease's progression and providing symptomatic relief. The clinical effectiveness of current treatment regimens has been limited by short half-lives of the drugs and the requirement for repeated systemic administration. Utilizing gene transfer approaches for the treatment of arthritis may overcome some of the obstacles associated with current treatment strategies. The present review examines recent developments in gene therapy for arthritis. Delivery strategies, gene transfer vectors, candidate genes, and safety are also discussed. PMID:18176779

Progress in the molecular diagnosis of Lyme disease.

PubMed

Ružić-Sabljić, Eva; Cerar, Tjaša

2017-01-01

Current laboratory testing of Lyme borreliosis mostly relies on serological methods with known limitations. Diagnostic modalities enabling direct detection of pathogen at the onset of the clinical signs could overcome some of the limitations. Molecular methods detecting borrelial DNA seem to be the ideal solution, although there are some aspects that need to be considered. Areas covered: This review represent summary and discussion of the published data obtained from literature searches from PubMed and The National Library of Medicine (USA) together with our own experience on molecular diagnosis of Lyme disease. Expert commentary: Molecular methods are promising and currently serve as supporting diagnostic testing in Lyme borreliosis. Since the field of molecular diagnostics is under rapid development, molecular testing could become an important diagnostic modality.

Could Wearable and Mobile Technology Improve the Management of Essential Tremor?

PubMed Central

Daneault, Jean-Francois

2018-01-01

Essential tremor (ET) is the most common movement disorder. Individuals exhibit postural and kinetic tremor that worsens over time and patients may also exhibit other motor and non-motor symptoms. While millions of people are affected by this disorder worldwide, several barriers impede an optimal clinical management of symptoms. In this paper, we discuss the impact of ET on patients and review major issues to the optimal management of ET; from the side-effects and limited efficacy of current medical treatments to the limited number of people who seek treatment for their tremor. Then, we propose seven different areas within which mobile and wearable technology may improve the clinical management of ET and review the current state of research in these areas. PMID:29725318

Robotics in invasive cardiac electrophysiology.

PubMed

Shurrab, Mohammed; Schilling, Richard; Gang, Eli; Khan, Ejaz M; Crystal, Eugene

2014-07-01

Robotic systems allow for mapping and ablation of different arrhythmia substrates replacing hand maneuvering of intracardiac catheters with machine steering. Currently there are four commercially available robotic systems. Niobe magnetic navigation system (Stereotaxis Inc., St Louis, MO) and Sensei robotic navigation system (Hansen Medical Inc., Mountain View, CA) have an established platform with at least 10 years of clinical studies looking at their efficacy and safety. AMIGO Remote Catheter System (Catheter Robotics, Inc., Mount Olive, NJ) and Catheter Guidance Control and Imaging (Magnetecs, Inglewood, CA) are in the earlier phases of implementations with ongoing feasibility and some limited clinical studies. This review discusses the advantages and limitations related to each existing system and highlights the ideal futuristic robotic system that may include the most promising features of the current ones.

Host-Directed Therapeutics as a Novel Approach for Tuberculosis Treatment.

PubMed

Kim, Ye-Ram; Yang, Chul-Su

2017-09-28

Despite significant efforts to improve the treatment of tuberculosis (TB), it remains a prevalent infectious disease worldwide owing to the limitations of current TB therapeutic regimens. Recent work on novel TB treatment strategies has suggested that directly targeting host factors may be beneficial for TB treatment. Such strategies, termed host-directed therapeutics (HDTs), focus on host-pathogen interactions. HDTs may be more effective than the currently approved TB drugs, which are limited by the long durations of treatment needed and the emergence of drug-resistant strains. Targets of HDTs include host factors such as cytokines, immune checkpoints, immune cell functions, and essential enzyme activities. This review article discusses examples of potentially promising HDTs and introduces novel approaches for their development.

How Can We Better Detect Unauthorized GMOs in Food and Feed Chains?

PubMed

Fraiture, Marie-Alice; Herman, Philippe; De Loose, Marc; Debode, Frédéric; Roosens, Nancy H

2017-06-01

Current GMO detection systems have limited abilities to detect unauthorized genetically modified organisms (GMOs). Here, we propose a new workflow, based on next-generation sequencing (NGS) technology, to overcome this problem. In providing information about DNA sequences, this high-throughput workflow can distinguish authorized and unauthorized GMOs by strengthening the tools commonly used by enforcement laboratories with the help of NGS technology. In addition, thanks to its massive sequencing capacity, this workflow could be used to monitor GMOs present in the food and feed chain. In view of its potential implementation by enforcement laboratories, we discuss this innovative approach, its current limitations, and its sustainability of use over time. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrogen Storage Materials for Mobile and Stationary Applications: Current State of the Art.

PubMed

Lai, Qiwen; Paskevicius, Mark; Sheppard, Drew A; Buckley, Craig E; Thornton, Aaron W; Hill, Matthew R; Gu, Qinfen; Mao, Jianfeng; Huang, Zhenguo; Liu, Hua Kun; Guo, Zaiping; Banerjee, Amitava; Chakraborty, Sudip; Ahuja, Rajeev; Aguey-Zinsou, Kondo-Francois

2015-09-07

One of the limitations to the widespread use of hydrogen as an energy carrier is its storage in a safe and compact form. Herein, recent developments in effective high-capacity hydrogen storage materials are reviewed, with a special emphasis on light compounds, including those based on organic porous structures, boron, nitrogen, and aluminum. These elements and their related compounds hold the promise of high, reversible, and practical hydrogen storage capacity for mobile applications, including vehicles and portable power equipment, but also for the large scale and distributed storage of energy for stationary applications. Current understanding of the fundamental principles that govern the interaction of hydrogen with these light compounds is summarized, as well as basic strategies to meet practical targets of hydrogen uptake and release. The limitation of these strategies and current understanding is also discussed and new directions proposed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hemispheric Patterns in Electric Current Helicity of Solar Magnetic Fields During Solar Cycle 24: Results from SOLIS, SDO and Hinode

NASA Astrophysics Data System (ADS)

Gusain, S.

2017-12-01

We study the hemispheric patterns in electric current helicity distribution on the Sun. Magnetic field vector in the photosphere is now routinely measured by variety of instruments. SOLIS/VSM of NSO observes full disk Stokes spectra in photospheric lines which are used to derive vector magnetograms. Hinode SP is a space based spectropolarimeter which has the same observable as SOLIS albeit with limited field-of-view (FOV) but high spatial resolution. SDO/HMI derives vector magnetograms from full disk Stokes measurements, with rather limited spectral resolution, from space in a different photospheric line. Further, these datasets now exist for several years. SOLIS/VSM from 2003, Hinode SP from 2006, and SDO HMI since 2010. Using these time series of vector magnetograms we compute the electric current density in active regions during solar cycle 24 and study the hemispheric distributions. Many studies show that the helicity parameters and proxies show a strong hemispheric bias, such that Northern hemisphere has preferentially negative and southern positive helicity, respectively. We will confirm these results for cycle 24 from three different datasets and evaluate the statistical significance of the hemispheric bias. Further, we discuss the solar cycle variation in the hemispheric helicity pattern during cycle 24 and discuss its implications in terms of solar dynamo models.

Practical cryptographic strategies in the post-quantum era

NASA Astrophysics Data System (ADS)

Kabanov, I. S.; Yunusov, R. R.; Kurochkin, Y. V.; Fedorov, A. K.

2018-02-01

Quantum key distribution technologies promise information-theoretic security and are currently being deployed in com-mercial applications. We review new frontiers in information security technologies in communications and distributed storage applications with the use of classical, quantum, hybrid classical-quantum, and post-quantum cryptography. We analyze the cur-rent state-of-the-art, critical characteristics, development trends, and limitations of these techniques for application in enterprise information protection systems. An approach concerning the selection of practical encryption technologies for enterprises with branched communication networks is discussed.

Hepatitis B Virus Infection in Tanzania: Current Status and Challenges

PubMed Central

Bakshi, Fatma A.; Jaka, Hyasinta

2018-01-01

Hepatitis B is one of the most common infectious diseases in the world with high prevalence in most of sub-Saharan Africa countries. The complexity in its diagnosis and treatment poses a significant management challenge in the resource-limited settings including Tanzania, where most of the tests and drugs are either unavailable or unaffordable. This mini review aims at demonstrating the current status of the disease in the country and discussing the concomitant challenges in diagnosis, treatment, and prevention. PMID:29666656

A cascaded Schwarz converter for high frequency power distribution

NASA Technical Reports Server (NTRS)

Ray, Biswajit; Stuart, Thomas A.

1988-01-01

It is shown that two Schwarz converters in cascade provide a very reliable 20-kHz source that features zero current commutation, constant frequency, and fault-tolerant operation, meeting requirements for spacecraft applications. A steady-state analysis of the converter is presented, and equations for the steady-state performance are derived. Fault-current limiting is discussed. Experimental results are presented for a 900-W version, which has been successfully tested under no-load, full-load, and short-circut conditions.

Active shielding of cylindrical saddle-shaped coils: application to wire-wound RF coils for very low field NMR and MRI.

PubMed

Bidinosti, C P; Kravchuk, I S; Hayden, M E

2005-11-01

We provide an exact expression for the magnetic field produced by cylindrical saddle-shaped coils and their ideal shield currents in the low-frequency limit. The stream function associated with the shield surface current is also determined. The results of the analysis are useful for the design of actively shielded radio-frequency (RF) coils. Examples pertinent to very low field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are presented and discussed.

How much CO2 can we still emit while limiting global warming to well below 2 °C?

NASA Astrophysics Data System (ADS)

Rahmstorf, S.

2017-12-01

In December 2015, the Paris Agreement signed by 195 nations agreed to limit global warming "to well below 2 °C above preindustrial levels and to pursue efforts to limit the temperature increase to 1.5 °C." Since the amount of global warming is approximately proportional to cumulative CO2 emissions, such a warming limit corresponds to a remaining "CO2 budget" - a total amount of CO2 that can still be emitted world-wide. I will discuss current estimates of the size of this CO2 budget and what this means for the emissions trajectories compatible with the Paris Agreement.

Novel methods to optimize the effects of transcranial direct current stimulation: a systematic review of transcranial direct current stimulation patents.

PubMed

Malavera, Alejandra; Vasquez, Alejandra; Fregni, Felipe

2015-01-01

Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that has been extensively studied. While there have been initial positive results in some clinical trials, there is still variability in tDCS results. The aim of this article is to review and discuss patents assessing novel methods to optimize the use of tDCS. A systematic review was performed using Google patents database with tDCS as the main technique, with patents filling date between 2010 and 2015. Twenty-two patents met our inclusion criteria. These patents attempt to address current tDCS limitations. Only a few of them have been investigated in clinical trials (i.e., high-definition tDCS), and indeed most of them have not been tested before in human trials. Further clinical testing is required to assess which patents are more likely to optimize the effects of tDCS. We discuss the potential optimization of tDCS based on these patents and the current experience with standard tDCS.

Implications of Marcus-Hush theory for steady-state heterogeneous electron transfer at an inlaid disk electrode.

PubMed

Feldberg, Stephen W

2010-06-15

For an outer-sphere heterogeneous electron transfer, Ox + e = Red, between an electrode and a redox couple, the Butler-Volmer formalism predicts that the operative heterogeneous rate constant, k(red) (cm s(-1)) for reduction (or k(ox) for oxidation) increases without limit as an exponential function of -alpha (E - E(0)) for reduction (or (1 - alpha)(E - E(0)) for oxidation), where E is the applied electrode potential, alpha (~1/2) is the transfer coefficient and E(0) is the formal potential. The Marcus-Hush formalism, as exposited by Chidsey (Chidsey, C. E. D. Science 1991, 215, 919), predicts that the value of k(red) or k(ox) limits at sufficiently large values of -(E - E(0)) or (E - E(0)). The steady-state currents at an inlaid disk electrode obtained for a redox species in solution were computed using both formalisms with the Oldham-Zoski approximation (Oldham, K. B.; Zoski, C. G. J. Electroanal. Chem. 1988, 256, 11). Significant differences are noted for the two formalisms. When k(0)r(0)/D is sufficiently small (k(0) is the standard rate constant, r(0) is the radius of the disk electrode, and D is the diffusion coefficient of the redox species), the Marcus-Hush formalism effects a limiting current that can be significantly smaller than the mass transport limited current. This is easily explained in terms of the limiting values of k(red) and k(ox) predicted by the Marcus-Hush formalism. The experimental conditions that must be met to effect significant differences in behavior are discussed; experimental conditions that effect virtually identical behavior are also discussed. As a caveat for experimentalists, applications of the Butler-Volmer formalism to systems that are more properly described using the Marcus-Hush formalism are shown to yield incorrect values of k(0) and meaningless values of alpha, which serves only as a fitting parameter.

Brothers, Sisters and Fictive Kin: Communication about Sex among Urban Black Siblings

ERIC Educational Resources Information Center

Wallace, Scyatta A.; Hooper, Lisa M.; Persad, Malini

2014-01-01

Siblings have been shown to influence youth substance use and violent behavior. However, limited research has examined sibling-influences on sexual activity, particularly among urban Black youth. The current qualitative research was an exploratory study to describe discussions among siblings about sex and sexual health. Individual interviews were…

Does Student Quality Matter in the Teaching of Economic Principles?

ERIC Educational Resources Information Center

Andreopoulos, Giuliana Campanelli; Panayides, Alexandros

2010-01-01

Economics is usually perceived as a difficult subject among undergraduate students and the literature suggests that the student's problems with principles of economics are mainly related to the chalk and talk type of teaching, the simplicity of economic models, limited discussions on current economic issues, and on race, gender, and other types of…

Educational contracts in family medicine residency training.

PubMed Central

Mahood, S.; Rojas, R.; Andres, D.; Zagozeski, C.; White, G.; Bradel, T.

1994-01-01

An educational contract for family medicine residency training and evaluation addresses many of the difficulties and challenges of current postgraduate medical education. This article identifies important principles for developing a contractual approach; describes the contract used in one program and its implementation; and discusses its theory, advantages, and limitations. Images p550-a PMID:8199512

Clearing a Path: The 16-Bit Operating System Jungle Offers Confusion, Not Standardization.

ERIC Educational Resources Information Center

Pournelle, Jerry

1984-01-01

Discusses the design and limited uses of the Pascal, MS-DOS, CP/M, and PC-DOS operating systems as standard operating systems for 16-bit microprocessors, especially with the more sophisticated microcomputers currently being developed. Advantages and disadvantages of Unix--a multitasking, multiuser operating system--as a standard operating system…

Intellectual Property and Aboriginal People: A Working Paper = Propriete intellectuelle et Autochtones: Document de travail.

ERIC Educational Resources Information Center

Brascoupe, Simon; Endemann, Karin

Written in English and French, this paper outlines current Canadian intellectual property legislation as it relates to Aboriginal people in Canada, and provides a general review of the implications and limitations of this legislation for protecting the traditional knowledge of Aboriginal people. An initial discussion of Aboriginal perspectives…

A Bourdieusian Approach to Understanding Employability: Becoming a "Fish in Water"

ERIC Educational Resources Information Center

Clark, Martyn; Zukas, Miriam

2013-01-01

It is assumed in the current policy environment that higher education should lead to graduate employability, although understandings of employability are generally limited. In this paper, we discuss issues relating to graduate employability with reference to a case study of an information technology (IT) student progressing to a graduate role in…

Teaching Notes: Reframing Multicultural Education--Teaching White Privilege in the Social Work Curriculum

ERIC Educational Resources Information Center

Abrams, Laura S.; Gibson, Priscilla

2007-01-01

This article proposes a model of teaching diversity in social work education that includes significant content on White privilege. The authors first discuss some limitations of social work's current multicultural framework. Next, they introduce concepts and pedagogical strategies concerning White identity and privilege that are drawn from…

An Exploratory Study of Practitioner Experiences of Sexual Addiction among Adolescents

ERIC Educational Resources Information Center

Wilkinson, Jason D.

2012-01-01

Sexual addiction is increasingly being discussed by professionals and the lay public, and these conversations have begun to focus on adolescents as a special treatment population. At the same time, limited literature is available on the subject and practitioners currently working with sexual addiction among adolescents (SA-A) report the need for…

Health Promotion and Complementary Medicine: The Extent and Future of Professional Collaboration and Integration

ERIC Educational Resources Information Center

Hill, Faith

2006-01-01

Purpose: To explore the professional interface between health promotion (HP) and complementary and alternative medicine. Design/methodology/approach: A discussion paper, based on qualitative research involving in-depth interviews with 52 participants from either side of the interface. Findings: The current interface is predominantly limited to…

78 FR 17993 - Defense Trade Advisory Group; Notice of Open Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-25

... policies, regulations, and technical issues affecting defense trade. The purpose of the meeting will be to... discussed: review of the current definitions of technical data, as well as the control language applied in... statement to the committee in writing. As seating is limited to 125 persons, those wishing to attend the...

[Ethical insolvency?].

PubMed

von Weizsäcker, F; Maio, G

2010-04-01

The current DRG system has not only changed the economic structure of clinical medicine but also has profound effects on its original mission. In the present paper we discuss the fundamental limits of the DRG system and make a case for placing more emphasis on time and communication in health care. Georg Thieme Verlag KG Stuttgart. New York.

Edutainment, Games, and the Future of Education in a Digital World

ERIC Educational Resources Information Center

Jarvin, Linda

2015-01-01

Since the development of educational television in the 1960s, there has been a growing interest in incorporating features of entertainment in informal and formal education. Reviewing the literature on edutainment and games, we will discuss the limits of the current state of research and propose research questions investigating broad issues linked…

Cellular Radio Telecommunication for Health Care: Benefits and Risks

PubMed Central

Sneiderman, Charles A.; Ackerman, Michael J.

2004-01-01

Cellular radio telecommunication has increased exponentially with many applications to health care reported. The authors attempt to summarize published applications with demonstrated effect on health care, review briefly the rapid evolution of hardware and software standards, explain current limitations and future potential of data quality and security, and discuss issues of safety. PMID:15298996

Enhanced use of CLIPS at the Los Alamos National Laboratory

NASA Technical Reports Server (NTRS)

Duerre, K. H.; Parkinson, W. J.; Osowski, J. J.

1991-01-01

Early efforts for producing expert systems for engineering applications used a limited subset of C Language Integrated Production System (CLIPS) features. The implementation details of previous expert systems and of the current expert system, which is used for training operators in the control of the Isotope Separation System, are discussed.

We Have the Videoconference Equipment Installed, Now What?

ERIC Educational Resources Information Center

Lim, Janine; Freed, Shirley

2009-01-01

As K-12 schools acquire equipment for videoconferencing, they often experience limited usage of the equipment. The purpose of this study was to identify specific concerns of educators currently involved in videoconferencing. The primary data for the study was 400 discussion posts from 34 educators in an online class about videoconferencing. Data…

Supporting Vocationally Oriented Learning in the High School Years: Rationale, Tasks, Challenges

ERIC Educational Resources Information Center

Halpern, Robert

2012-01-01

This article highlights the limitations of our current educational system in terms of vocational learning and highlights the role that vocational learning can play in supporting youth development and improving youth outcomes. It discusses the role that nonschool settings can play in supporting vocational learning and suggests strategies to improve…

Getting Help: Finding an Answer to a Specific Problem is Almost Impossible These Days.

ERIC Educational Resources Information Center

Levy, Steven

1984-01-01

Discusses the very limited information sources currently available to microcomputer users, including computer salespersons, user support groups, and computer books, and suggests that the newly emerging hotline-style computer advisory services may be able to provide the accurate answers and expert advice not easily available elsewhere. (MBR)

Improving Access to Accommodations: Reducing Political and Institutional Barriers for Canadian Postsecondary Students with Visual Impairments

ERIC Educational Resources Information Center

Ostrowski, Christopher P.

2016-01-01

Challenges to obtaining quality academic accommodations for students with visual impairments in postsecondary education hinder accessibility and the success of such students. The limitations of current policies and practices intended to address the needs of students in Canada are examined and potential solutions are discussed. Further systemic…

Current and Future Perspectives on Alginate Encapsulated Pancreatic Islet.

PubMed

Strand, Berit L; Coron, Abba E; Skjak-Braek, Gudmund

2017-04-01

Transplantation of pancreatic islets in immune protective capsules holds the promise as a functional cure for type 1 diabetes, also about 40 years after the first proof of principal study. The concept is simple in using semipermeable capsules that allow the ingress of oxygen and nutrients, but limit the access of the immune system. Encapsulated human islets have been evaluated in four small clinical trials where the procedure has been evaluated as safe, but lacking long-term efficacy. Host reactions toward the biomaterials used in the capsules may be one parameter limiting the long-term function of the graft in humans. The present article briefly discusses important capsule properties such as stability, permeability and biocompatibility, as well as possible strategies to overcome current challenges. Also, recent progress in capsule development as well as the production of insulin-producing cells from human stem cells that gives promising perspectives for the transplantation of encapsulated insulin-producing tissue is briefly discussed. Stem Cells Translational Medicine 2017;6:1053-1058. © 2017 The Authors Stem Cells Translational Medicine published by Wiley Periodicals, Inc. on behalf of AlphaMed Press.

Structural design principles for delivery of bioactive components in nutraceuticals and functional foods.

PubMed

McClements, David Julian; Decker, Eric Andrew; Park, Yeonhwa; Weiss, Jochen

2009-06-01

There have been major advances in the design and fabrication of structured delivery systems for the encapsulation of nutraceutical and functional food components. A wide variety of delivery systems is now available, each with its own advantages and disadvantages for particular applications. This review begins by discussing some of the major nutraceutical and functional food components that need to be delivered and highlights the main limitations to their current utilization within the food industry. It then discusses the principles underpinning the rational design of structured delivery systems: the structural characteristics of the building blocks; the nature of the forces holding these building blocks together; and, the different ways of assembling these building blocks into structured delivery systems. Finally, we review the major types of structured delivery systems that are currently available to food scientists: lipid-based (simple, multiple, multilayer, and solid lipid particle emulsions); surfactant-based (simple micelles, mixed micelles, vesicles, and microemulsions) and biopolymer-based (soluble complexes, coacervates, hydrogel droplets, and particles). For each type of delivery system we describe its preparation, properties, advantages, and limitations.

Alteration processes of alkenones and related lipids in water columns and sediments

NASA Astrophysics Data System (ADS)

Harvey, H. Rodger

2000-08-01

Alkenones produced by the haptophyte algae are currently being used as indices of sea surface temperature in recent and past ocean environments, but limited information is available concerning the impact of biotic and abiotic processes on the integrity of these long chain lipids. This synthesis provides selected background information on major alteration processes that must be considered before such indices can be used with confidence. A number of processes in the water column and surface sediments have the potential to impact the structural integrity of alkenones and compromise their ability as temperature markers. Processes discussed include the alteration of alkenone structure during early diagenesis, direct biotic and abiotic impacts, and the effect of digestive processes by grazers. Current literature suggests that despite substantial changes in concentration from biological processing, the temperature signal is preserved. For each of these processes, information on the integrity of the alkenone isotopic signature is also needed and limited information available is reviewed. In addition to the alkenones, related lipids including the long chain alkadienes and akyl alkenoates that might serve as ancillary markers are discussed.

A modification of Murray's law for shear-thinning rheology.

PubMed

McGah, Patrick M; Capobianchi, Massimo

2015-05-01

This study reformulates Murray's well-known principle of minimum work as applied to the cardiovascular system to include the effects of the shear-thinning rheology of blood. The viscous behavior is described using the extended modified power law (EMPL), which is a time-independent, but shear-thinning rheological constitutive equation. The resulting minimization problem is solved numerically for typical parameter ranges. The non-Newtonian analysis still predicts the classical cubic diameter dependence of the volume flow rate and the cubic branching law. The current analysis also predicts a constant wall shear stress throughout the vascular tree, albeit with a numerical value about 15-25% higher than the Newtonian analysis. Thus, experimentally observed deviations from the cubic branching law or the predicted constant wall shear stress in the vasculature cannot likely be attributed to blood's shear-thinning behavior. Further differences between the predictions of the non-Newtonian and the Newtonian analyses are highlighted, and the limitations of the Newtonian analysis are discussed. Finally, the range and limits of applicability of the current results as applied to the human arterial tree are also discussed.

Use of analgesic and sedative drugs in the NICU: integrating clinical trials and laboratory data.

PubMed

Durrmeyer, Xavier; Vutskits, Laszlo; Anand, Kanwaljeet J S; Rimensberger, Peter C

2010-02-01

Recent advances in neonatal intensive care include and are partly attributable to growing attention for comfort and pain control in the term and preterm infant requiring intensive care.Limitation of painful procedures is certainly possible, but most critically ill infants require unavoidable painful or stressful procedures such as intubation, mechanical ventilation, or catheterization.Many analgesics (opioids and nonsteroidal anti-inflammatory drugs)and sedatives (benzodiazepines and other anesthetic agents) are available but their use varies considerably among units. This review summarizes current experimental knowledge on the effects of sedative and analgesic drugs on brain development and reviews clinical evidence that speaks for or against the use of common analgesic and sedative drugs in the NICU but avoids any discussion of anesthesia during surgery. Risk/benefit ratios of intermittent boluses or continuous infusions for the commonly used sedative and analgesic agents are discussed in the light of clinical and experimental studies. The limitations of extrapolating experimental results from animals to humans must be considered while making practical recommendations based on the currently available evidence.

A new flux-limited, two-dimensional, nonsymmetric tensor shock viscosity for DYNA2D: Progress report

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

Benson, D.J.

1988-08-15

A new artificial viscosity that is being developed for DYNA2D is described in this progress report. It incorporates the one- dimensional, flux-limited viscosity developed by Randy Christensen into a two-dimensional setting. In addition, it tries to overcome some of the difficulties associated with traditional bulk viscosity formulations by using an nonsymmetric viscosity tensor. A different nonsymmetric approach (and a symmetrized version of it) is being used in SHALE by Len Margolin with great success. In a later section of this paper, the results of DYNA2D and SHALE for the ''Saltzman problem'' are compared. The general organization of this report ismore » as follows: First it presents the one-dimensional, flux-limited viscosity developed by Christensen. An nonsymmetric tensor viscosity is then developed and the addition of flux-limiting to it is discussed. The issue of boundary conditions turns out to be crucial, and some issues associated with them are unresolved. The current boundary conditions and the issues associated with them are discussed. Example calculations are also given. The current work is summarized and future work is outlined in the first chapter. This brief progress report is the basis of a future journal paper. The work presented in here is unfinished, and some of the results and algorithms will undoubtedly be changed before the final paper. No attempt has been made to survey the results of others in this report, but a limited survey will be incorporated in the journal paper. 7 refs., 39 figs.« less

Study and design of the ion cyclotron resonance heating system for the stellarator Wendelstein 7-X

NASA Astrophysics Data System (ADS)

Ongena, J.; Messiaen, A.; Van Eester, D.; Schweer, B.; Dumortier, P.; Durodie, F.; Kazakov, Ye. O.; Louche, F.; Vervier, M.; Koch, R.; Krivska, A.; Lyssoivan, A.; Van Schoor, M.; Wauters, T.; Borsuk, V.; Neubauer, O.; Schmitz, O.; Offermans, G.; Altenburg, Y.; Baylard, C.; Birus, D.; Bozhenkov, S.; Hartmann, D. A.; Kallmeyer, J. P.; Renard, S.; Wolf, R. C.; Fülöp, T.

2014-06-01

The current status of the mechanical and electromagnetic design for the ICRF antenna system for W7-X is presented. Two antenna plugins are discussed: one consisting of a pair of straps with pre-matching to cover the first frequency band, 25-38 MHz, and a second one consisting of two short strap triplets to cover a frequency band around 76 MHz. This paper focusses on the two strap antenna for the lower frequency band. Power coupling of the antenna to a reference plasma profile is studied with the help of the codes TOPICA and Microwave Studio that deliver the scattering matrix needed for the optimization of the geometric parameters of the straps and antenna box. Radiation power spectra for different phasings of the two straps are obtained using the code ANTITER II and different heating scenario are discussed. The potential for heating, fast particle generation, and current drive is discussed. The problem of RF coupling through the plasma edge and of edge power deposition is summarized. Important elements of the complete ion cyclotron resonance heating system are discussed: a resonator circuit with tap feed to limit the maximum voltage in the system, and a decoupler to counterbalance the large mutual coupling between the 2 straps. The mechanical design highlights the challenges encountered with this antenna: adaptation to a large variety of plasma configurations, the limited space within the port to accommodate the necessary matching components and the watercooling needed for long pulse operation.

Achieving development goals for HIV, tuberculosis and malaria in sub-Saharan Africa through integrated antenatal care: barriers and challenges.

PubMed

Fowkes, Freya J I; Draper, Bridget L; Hellard, Margaret; Stoové, Mark

2016-12-12

The global health community is currently transitioning from the Millennium Development Goals (MDGs) to the Sustainable Development Goals (SDGs). Unfortunately, progress towards maternal, newborn and infant health MDGs has lagged significantly behind other key health goals, demanding a renewed global effort in this key health area. The World Health Organization and other institutions heralded integrated antenatal care (ANC) as the best way to address the inter-related health issues of HIV, tuberculosis (TB) and malaria in the high risk groups of pregnant women and infants; integrated ANC services also offer a mechanism to address slow progress towards improved maternal health. There is remarkably limited evidence on best practice approaches of program implementation, acceptability and effectiveness for integrated ANC models targeting multiple diseases. Here, we discuss current integrated ANC global guidelines and the limited literature describing integrated ANC implementation and evidence for their role in addressing HIV, malaria and TB during pregnancy in sub-Saharan Africa. We highlight the paucity of data on the effectiveness of integrated ANC models and identify significant structural barriers in the health system (funding, infrastructure, distribution, human resources), the adoption system (limited buy-in from implementers, leadership, governance) and, in the broader context, patient-centred barriers (fear, stigma, personal burdens) and barriers in funding structures. We highlight recommendations for action and discuss avenues for the global health community to develop systems to integrate multiple disease programs into ANC models of care that better address these three priority infectious diseases. With the current transition to the SDGs and concerns regarding the failure to meet maternal health MDGs, the global health community, researchers, implementers and funding bodies must work together to ensure the establishment of quality operational and implementation research to inform integrated ANC models. It is imperative that the global health community engages in a timely discussion about such implementation innovations and instigates appropriate actions to ensure advances in maternal health are sufficient to meet applicable SDGs.

Negative emissions: Part 1—research landscape and synthesis

NASA Astrophysics Data System (ADS)

Minx, Jan C.; Lamb, William F.; Callaghan, Max W.; Fuss, Sabine; Hilaire, Jérôme; Creutzig, Felix; Amann, Thorben; Beringer, Tim; de Oliveira Garcia, Wagner; Hartmann, Jens; Khanna, Tarun; Lenzi, Dominic; Luderer, Gunnar; Nemet, Gregory F.; Rogelj, Joeri; Smith, Pete; Vicente, Jose Luis Vicente; Wilcox, Jennifer; del Mar Zamora Dominguez, Maria

2018-06-01

With the Paris Agreement’s ambition of limiting climate change to well below 2 °C, negative emission technologies (NETs) have moved into the limelight of discussions in climate science and policy. Despite several assessments, the current knowledge on NETs is still diffuse and incomplete, but also growing fast. Here, we synthesize a comprehensive body of NETs literature, using scientometric tools and performing an in-depth assessment of the quantitative and qualitative evidence therein. We clarify the role of NETs in climate change mitigation scenarios, their ethical implications, as well as the challenges involved in bringing the various NETs to the market and scaling them up in time. There are six major findings arising from our assessment: first, keeping warming below 1.5 °C requires the large-scale deployment of NETs, but this dependency can still be kept to a minimum for the 2 °C warming limit. Second, accounting for economic and biophysical limits, we identify relevant potentials for all NETs except ocean fertilization. Third, any single NET is unlikely to sustainably achieve the large NETs deployment observed in many 1.5 °C and 2 °C mitigation scenarios. Yet, portfolios of multiple NETs, each deployed at modest scales, could be invaluable for reaching the climate goals. Fourth, a substantial gap exists between the upscaling and rapid diffusion of NETs implied in scenarios and progress in actual innovation and deployment. If NETs are required at the scales currently discussed, the resulting urgency of implementation is currently neither reflected in science nor policy. Fifth, NETs face severe barriers to implementation and are only weakly incentivized so far. Finally, we identify distinct ethical discourses relevant for NETs, but highlight the need to root them firmly in the available evidence in order to render such discussions relevant in practice.

Spheromak Formation and Current Sustainment Using a Repetitively Pulsed Source

NASA Astrophysics Data System (ADS)

Woodruff, S.; Macnab, A. I. D.; Ziemba, T. M.; Miller, K. E.

2009-06-01

By repeated injection of magnetic helicity ( K = 2φψ) on time-scales short compared with the dissipation time (τinj << τ K ), it is possible to produce toroidal currents relevant to POP-level experiments. Here we discuss an effective injection rate, due to the expansion of a series of current sheets and their subsequent reconnection to form spheromaks and compression into a copper flux-conserving chamber. The benefits of repeated injection are that the usual limits to current amplification can be exceeded, and an efficient quasi-steady sustainment scenario is possible (within minimum impact on confinement). A new experiment designed to address the physics of pulsed formation and sustainment is described.

Whispering-Gallery Mode Resonators for Detecting Cancer

PubMed Central

Pongruengkiat, Weeratouch; Pechprasarn, Suejit

2017-01-01

Optical resonators are sensors well known for their high sensitivity and fast response time. These sensors have a wide range of applications, including in the biomedical fields, and cancer detection is one such promising application. Sensor diagnosis currently has many limitations, such as being expensive, highly invasive, and time-consuming. New developments are welcomed to overcome these limitations. Optical resonators have high sensitivity, which enable medical testing to detect disease in the early stage. Herein, we describe the principle of whispering-gallery mode and ring optical resonators. We also add to the knowledge of cancer biomarker diagnosis, where we discuss the application of optical resonators for specific biomarkers. Lastly, we discuss advancements in optical resonators for detecting cancer in terms of their ability to detect small amounts of cancer biomarkers. PMID:28902169

Dark matter effective field theory scattering in direct detection experiments

DOE PAGES

Schneck, K.

2015-05-01

We examine the consequences of the effective field theory (EFT) of dark matter–nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implicationsmore » of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.« less

Dark matter effective field theory scattering in direct detection experiments

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

Schneck, K.; Cabrera, B.; Cerdeño, D. G.

2015-05-18

We examine the consequences of the effective field theory (EFT) of dark matter–nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implicationsmore » of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.« less

Universality of Non-Ohmic Shunt Leakage in Thin-Film Solar Cells

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

Dongaonkar, S.; Servaites, J.D.; Ford, G.M.

2010-01-01

We compare the dark current-voltage (IV) characteristics of three different thin-film solar cell types: hydrogenated amorphous silicon (a-Si:H) p-i-n cells, organic bulk heterojunction (BHJ) cells, and Cu(In,Ga)Se 2 (CIGS) cells. All three device types exhibit a significant shunt leakage current at low forward bias (V<~0.4) and reverse bias, which cannot be explained by the classical solar cell diode model. This parasitic shunt current exhibits non-Ohmic behavior, as opposed to the traditional constant shunt resistance model for photovoltaics. We show here that this shunt leakage (I sh) , across all three solar cell types considered, is characterized by the following commonmore » phenomenological features: (a) voltage symmetry about V=0 , (b) nonlinear (power law) voltage dependence, and (c) extremely weak temperature dependence. Based on this analysis, we provide a simple method of subtracting this shunt current component from the measured data and discuss its implications on dark IV parameter extraction. We propose a space charge limited (SCL) current model for capturing all these features of the shunt leakage in a consistent framework and discuss possible physical origin of the parasitic paths responsible for this shunt current mechanism.« less

Receptor-mediated gene transfer vectors: progress towards genetic pharmaceuticals.

PubMed

Molas, M; Gómez-Valadés, A G; Vidal-Alabró, A; Miguel-Turu, M; Bermudez, J; Bartrons, R; Perales, J C

2003-10-01

Although specific delivery to tissues and unique cell types in vivo has been demonstrated for many non-viral vectors, current methods are still inadequate for human applications, mainly because of limitations on their efficiencies. All the steps required for an efficient receptor-mediated gene transfer process may in principle be exploited to enhance targeted gene delivery. These steps are: DNA/vector binding, internalization, subcellular trafficking, vesicular escape, nuclear import, and unpacking either for transcription or other functions (i.e., antisense, RNA interference, etc.). The large variety of vector designs that are currently available, usually aimed at improving the efficiency of these steps, has complicated the evaluation of data obtained from specific derivatives of such vectors. The importance of the structure of the final vector and the consequences of design decisions at specific steps on the overall efficiency of the vector will be discussed in detail. We emphasize in this review that stability in serum and thus, proper bioavailability of vectors to their specific receptors may be the single greatest limiting factor on the overall gene transfer efficiency in vivo. We discuss current approaches to overcome the intrinsic instability of synthetic vectors in the blood. In this regard, a summary of the structural features of the vectors obtained from current protocols will be presented and their functional characteristics evaluated. Dissecting information on molecular conjugates obtained by such methodologies, when carefully evaluated, should provide important guidelines for the creation of effective, targeted and safe DNA therapeutics.

Start Up Application Concerns with Field Programmable Gate Arrays (FPGAs)

NASA Technical Reports Server (NTRS)

Katz, Richard B.

1999-01-01

This note is being published to improve the visibility of this subject, as we continue to see problems surface in designs, as well as to add additional information to the previously published note for design engineers. The original application note focused on designing systems with no single point failures using Actel Field Programmable Gate Arrays (FPGAs) for critical applications. Included in that note were the basic principles of operation of the Actel FPGA and a discussion of potential single-point failures. The note also discussed the issue of startup transients for that class of device. It is unfortunate that we continue to see some design problems using these devices. This note will focus on the startup properties of certain electronic components, in general, and current Actel FPGAs, in particular. Devices that are "power-on friendly" are currently being developed by Actel, as a variant of the new SX series of FPGAs. In the ideal world, electronic components would behave much differently than they do in the real world, The chain, of course, starts with the power supply. Ideally, the voltage will immediately rise to a stable V(sub cc) level, of course, it does not. Aside from practical design considerations, inrush current limits of certain capacitors must be observed and the power supply's output may be intentionally slew rate limited to prevent a large current spike on the system power bus. In any event, power supply rise time may range from less than I msec to 100 msec or more.

Summary report of PQRI Workshop on Nanomaterial in Drug Products: current experience and management of potential risks.

PubMed

Bartlett, Jeremy A; Brewster, Marcus; Brown, Paul; Cabral-Lilly, Donna; Cruz, Celia N; David, Raymond; Eickhoff, W Mark; Haubenreisser, Sabine; Jacobs, Abigail; Malinoski, Frank; Morefield, Elaine; Nalubola, Ritu; Prud'homme, Robert K; Sadrieh, Nakissa; Sayes, Christie M; Shahbazian, Hripsime; Subbarao, Nanda; Tamarkin, Lawrence; Tyner, Katherine; Uppoor, Rajendra; Whittaker-Caulk, Margaret; Zamboni, William

2015-01-01

At the Product Quality Research Institute (PQRI) Workshop held last January 14-15, 2014, participants from academia, industry, and governmental agencies involved in the development and regulation of nanomedicines discussed the current state of characterization, formulation development, manufacturing, and nonclinical safety evaluation of nanomaterial-containing drug products for human use. The workshop discussions identified areas where additional understanding of material attributes, absorption, biodistribution, cellular and tissue uptake, and disposition of nanosized particles would continue to inform their safe use in drug products. Analytical techniques and methods used for in vitro characterization and stability testing of formulations containing nanomaterials were discussed, along with their advantages and limitations. Areas where additional regulatory guidance and material characterization standards would help in the development and approval of nanomedicines were explored. Representatives from the US Food and Drug Administration (USFDA), Health Canada, and European Medicines Agency (EMA) presented information about the diversity of nanomaterials in approved and newly developed drug products. USFDA, Health Canada, and EMA regulators discussed the applicability of current regulatory policies in presentations and open discussion. Information contained in several of the recent EMA reflection papers was discussed in detail, along with their scope and intent to enhance scientific understanding about disposition, efficacy, and safety of nanomaterials introduced in vivo and regulatory requirements for testing and market authorization. Opportunities for interaction with regulatory agencies during the lifecycle of nanomedicines were also addressed at the meeting. This is a summary of the workshop presentations and discussions, including considerations for future regulatory guidance on drug products containing nanomaterials.

Advances in native high-performance liquid chromatography and intact mass spectrometry for the characterization of biopharmaceutical products.

PubMed

Tassi, Marco; De Vos, Jelle; Chatterjee, Sneha; Sobott, Frank; Bones, Jonathan; Eeltink, Sebastiaan

2018-01-01

The characterization of biotherapeutics represents a major analytical challenge. This review discusses the current state-of-the-art in analytical technologies to profile biopharma products under native conditions, i.e., the protein three dimensional conformation is maintained during liquid chromatographic analysis. Native liquid-chromatographic modes that are discussed include aqueous size-exclusion chromatography, hydrophobic interaction chromatography, and ion-exchange chromatography. Infusion conditions and the possibilities and limitations to hyphenate native liquid chromatography to mass spectrometry are discussed. Furthermore, the applicability of native liquid-chromatography methods and intact mass spectrometry analysis for the characterization of monoclonal antibodies and antibody-drug conjugates is discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetic Recording Media Technology for the Tb/in2 Era"

ScienceCinema

Bertero, Gerardo [Western Digital

2017-12-09

Magnetic recording has been the technology of choice of massive storage of information. The hard-disk drive industry has recently undergone a major technological transition from longitudinal magnetic recording (LMR) to perpendicular magnetic recording (PMR). However, convention perpendicular recording can only support a few new product generations before facing insurmountable physical limits. In order to support sustained recording areal density growth, new technological paradigms, such as energy-assisted recording and bit-patterined media recording are being contemplated and planned. In this talk, we will briefly discuss the LMR-to-PMR transition, the extendibility of current PMR recording, and the nature and merits of new enabling technologies. We will also discuss a technology roadmap toward recording densities approaching 10 Tv/in2, approximately 40 times higher than in current disk drives.

The brain and the law.

PubMed Central

Chorvat, Terrence; McCabe, Kevin

2004-01-01

Much has been written about how law as an institution has developed to solve many problems that human societies face. Inherent in all of these explanations are models of how humans make decisions. This article discusses what current neuroscience research tells us about the mechanisms of human decision making of particular relevance to law. This research indicates that humans are both more capable of solving many problems than standard economic models predict, but also limited in ways those models ignore. This article discusses how law is both shaped by our cognitive processes and also shapes them. The article considers some of the implications of this research for improving our understanding of how our current legal regimes operate and how the law can be structured to take advantage of our neural mechanisms to improve social welfare. PMID:15590613

Experimental evidence for a transient Tayler instability in a cylindrical liquid-metal column.

PubMed

Seilmayer, Martin; Stefani, Frank; Gundrum, Thomas; Weier, Tom; Gerbeth, Gunter; Gellert, Marcus; Rüdiger, Günther

2012-06-15

In the current-driven, kink-type Tayler instability (TI) a sufficiently strong azimuthal magnetic field becomes unstable against nonaxisymmetric perturbations. The TI has been discussed as a possible ingredient of the solar dynamo mechanism and a source of the helical structures in cosmic jets. It is also considered as a size-limiting factor for liquid metal batteries. We report on a liquid metal TI experiment using a cylindrical column of the eutectic alloy GaInSn to which electrical currents of up to 8 kA are applied. We present results of external magnetic field measurements that indicate the transient occurrence of the TI in good agreement with numerical predictions. The interference of TI with the competing large-scale convection, resulting from Joule heating, is also discussed.

Computer-aided drug discovery.

PubMed

Bajorath, Jürgen

2015-01-01

Computational approaches are an integral part of interdisciplinary drug discovery research. Understanding the science behind computational tools, their opportunities, and limitations is essential to make a true impact on drug discovery at different levels. If applied in a scientifically meaningful way, computational methods improve the ability to identify and evaluate potential drug molecules, but there remain weaknesses in the methods that preclude naïve applications. Herein, current trends in computer-aided drug discovery are reviewed, and selected computational areas are discussed. Approaches are highlighted that aid in the identification and optimization of new drug candidates. Emphasis is put on the presentation and discussion of computational concepts and methods, rather than case studies or application examples. As such, this contribution aims to provide an overview of the current methodological spectrum of computational drug discovery for a broad audience.

Gate-tunable current partition in graphene-based topological zero lines

NASA Astrophysics Data System (ADS)

Wang, Ke; Ren, Yafei; Deng, Xinzhou; Yang, Shengyuan A.; Jung, Jeil; Qiao, Zhenhua

2017-06-01

We demonstrate new mechanisms for gate-tunable current partition at topological zero-line intersections in a graphene-based current splitter. Based on numerical calculations of the nonequilibrium Green's functions and Landauer-Büttiker formula, we show that the presence of a perpendicular magnetic field on the order of a few Teslas allows for carrier sign dependent current routing. In the zero-field limit the control on current routing and partition can be achieved within a range of 10-90 % of the total incoming current by tuning the carrier density at tilted intersections or by modifying the relative magnitude of the bulk band gaps via gate voltage. We discuss the implications of our findings in the design of topological zero-line networks where finite orbital magnetic moments are expected when the current partition is asymmetric.

Conducting Polyaniline Nanowire and Its Applications in Chemiresistive Sensing

PubMed Central

Song, Edward; Choi, Jin-Woo

2013-01-01

One dimensional polyaniline nanowire is an electrically conducting polymer that can be used as an active layer for sensors whose conductivity change can be used to detect chemical or biological species. In this review, the basic properties of polyaniline nanowires including chemical structures, redox chemistry, and method of synthesis are discussed. A comprehensive literature survey on chemiresistive/conductometric sensors based on polyaniline nanowires is presented and recent developments in polyaniline nanowire-based sensors are summarized. Finally, the current limitations and the future prospect of polyaniline nanowires are discussed. PMID:28348347

Aerodynamic studies of delta-wing shuttle orbiters. Part 1: Low speed

NASA Technical Reports Server (NTRS)

Freeman, D. C., Jr.; Ellison, J. C.

1972-01-01

Numerous wind tunnel tests conducted on the evolving delta-wing orbiters have generated a fairly large aerodynamic data base over the entire entry operation range of these vehicles. A limited assessment is made of some of the aerodynamics of the current HO type orbiters, and several specific problem areas selected from the broad data base are discussed. These include, from a subsonic viewpoint, discussions of trim drag effect; effects of the installation of main rocket engine nozzles, OMS and RCS packages, Reynolds number effects, lateral-directional stability characteristics, and landing characteristics.

Recent advances in hypersonic technology

NASA Technical Reports Server (NTRS)

Dwoyer, Douglas L.

1990-01-01

This paper will focus on recent advances in hypersonic aerodynamic prediction techniques. Current capabilities of existing numerical methods for predicting high Mach number flows will be discussed and shortcomings will be identified. Physical models available for inclusion into modern codes for predicting the effects of transition and turbulence will also be outlined and their limitations identified. Chemical reaction models appropriate to high-speed flows will be addressed, and the impact of their inclusion in computational fluid dynamics codes will be discussed. Finally, the problem of validating predictive techniques for high Mach number flows will be addressed.

Evolution of the Birth Plan

PubMed Central

Kaufman, Tamara

2007-01-01

Many birth professionals are discarding the birth plan as an outdated and ineffectual document. This column discusses the past limitations and present uses of the birth plan in an effort to enhance current teaching on how expectant parents can write and use this important document. Encouraging expectant parents to prepare two separate, but corresponding, birth plans—the “Discussion Birth Plan” and the “Hospital Birth Plan”—is proposed. Teaching suggestions and possible implications are explored in order to give childbirth educators practical information to share with their class members. PMID:18566650

Research on combustion instability and application to solid propellant rocket motors. II.

NASA Technical Reports Server (NTRS)

Culick, F. E. C.

1972-01-01

Review of the current state of analyses of combustion instability in solid-propellant rocket motors, citing appropriate measurements and observations. The work discussed has become increasingly important, both for the interpretation of laboratory data and for predicting the transient behavior of disturbances in full-scale motors. Two central questions are considered - namely, linear stability and nonlinear behavior. Several classes of problems are discussed as special cases of a general approach to the analysis of combustion instability. Application to motors, and particularly the limitations presently understood, are stressed.

Solid state, S-band, power amplifier

NASA Technical Reports Server (NTRS)

Digrindakis, M.

1973-01-01

The final design and specifications for a solid state, S-band, power amplifier is reported. Modifications from a previously proposed design were incorporated to improve efficiency and meet input overdrive and noise floor requirements. Reports on the system design, driver amplifier, power amplifier, and voltage and current limiter are included along with a discussion of the testing program.

Free Community College: An Approach to Increase Adult Student Success in Postsecondary Education. Special Report

ERIC Educational Resources Information Center

Pingel, Sarah; Parker, Emily; Sisneros, Lauren

2016-01-01

This policy report discusses the growing interest in free community college policies across state legislatures, addresses the limited potential of current policies to help states reach their completion and attainment goals and offers a new, inclusive framework for including adult students in free community college policies. The following is…

Grid related issues for static and dynamic geometry problems using systems of overset structured grids

NASA Technical Reports Server (NTRS)

Meakin, Robert L.

1995-01-01

Grid related issues of the Chimera overset grid method are discussed in the context of a method of solution and analysis of unsteady three-dimensional viscous flows. The state of maturity of the various pieces of support software required to use the approach is considered. Current limitations of the approach are identified.

A comparison of differential reinforcement procedures with children with autism.

PubMed

Boudreau, Brittany A; Vladescu, Jason C; Kodak, Tiffany M; Argott, Paul J; Kisamore, April N

2015-12-01

The current evaluation compared the effects of 2 differential reinforcement arrangements and a nondifferential reinforcement arrangement on the acquisition of tacts for 3 children with autism. Participants learned in all reinforcement-based conditions, and we discuss areas for future research in light of these findings and potential limitations. © Society for the Experimental Analysis of Behavior.

European Credit Transfer and Accumulation System: An Alternative Way to Calculate the ECTS Grades

ERIC Educational Resources Information Center

Grosges, Thomas; Barchiesi, Dominique

2007-01-01

The European Credit Transfer and Accumulation System (ECTS) has been developed and instituted to facilitate student mobility and academic recognition. This paper presents, discusses, and illustrates the pertinence and the limitation of the current statistical distribution of the ECTS grades, and we propose an alternative way to calculate the ECTS…

Sandbox CCDs

NASA Astrophysics Data System (ADS)

Janesick, James R.; Elliott, Tom S.; Winzenread, Rusty; Pinter, Jeff H.; Dyck, Rudolph H.

1995-04-01

Seven new CCDs are presented. The devices will be used in a variety of applications ranging from generating color cinema movies to adaptive optics camera systems to compensate for atmospheric turbulence at major astronomical observatories. This paper highlights areas of design, fabrication, and operation techniques to achieve state-of-the-art performance. We discuss current limitations of CCD technology for several key parameters.

Expert Systems in Education and Training: Automated Job Aids or Sophisticated Instructional Media?

ERIC Educational Resources Information Center

Romiszowski, Alexander J.

1987-01-01

Describes the current status and limitations of expert systems, and explores the possible applications of such systems in education and training. The use of expert systems as tutors, as job aids, and as a vehicle for students to develop their own expert systems on specific topics are discussed. (40 references) (CLB)

Why Can't a Teacher Be More like a Scientist? Science, Pseudoscience and the Art of Teaching

ERIC Educational Resources Information Center

Carter, Mark; Wheldall, Kevin

2008-01-01

In this article, the authors argue the case for scientific evidenced-based practice in education. They consider what differentiates science from pseudoscience and what sources of information teachers typically regard as reliable. The What Works Clearinghouse is discussed with reference to certain limitations of its current operation. Given the…

Introduction to the Special Section: Toward a Dimensionally Based Taxonomy of Psychopathology

PubMed Central

Krueger, Robert F.; Watson, David; Barlow, David H.

2008-01-01

Much current psychopathology research is framed by categorical constructs. Limitations of categorical constructs have been articulated, and dimensional constructs are often proposed as viable alternatives to categories of psychopathology. The purpose of this Special Section is to articulate and discuss diverse issues that arise in contemplating dimensional constructs as targets for psychopathology research. PMID:16351372

American Social Welfare Policy and Social Justice for Appalachia's Children.

ERIC Educational Resources Information Center

McNutt, John G.

This paper examines social welfare policy and its impacts on Appalachian children. The discussion is based on a notion that a just society meets basic needs of all its members. Current social policy: (1) does not include a comprehensive family policy; (2) depends on state and local contributions which are limited in rural Appalachia; (3) has…

The Evolving Landscape of HIV Drug Resistance Diagnostics for Expanding Testing in Resource-Limited Settings.

PubMed

Inzaule, Seth C; Hamers, Ralph L; Paredes, Roger; Yang, Chunfu; Schuurman, Rob; Rinke de Wit, Tobias F

2017-01-01

Global scale-up of antiretroviral treatment has dramatically changed the prospects of HIV/AIDS disease, rendering life-long chronic care and treatment a reality for millions of HIV-infected patients. Affordable technologies to monitor antiretroviral treatment are needed to ensure long-term durability of limited available drug regimens. HIV drug resistance tests can complement existing strategies in optimizing clinical decision-making for patients with treatment failure, in addition to facilitating population-based surveillance of HIV drug resistance. This review assesses the current landscape of HIV drug resistance technologies and discusses the strengths and limitations of existing assays available for expanding testing in resource-limited settings. These include sequencing-based assays (Sanger sequencing assays and nextgeneration sequencing), point mutation assays, and genotype-free data-based prediction systems. Sanger assays are currently considered the gold standard genotyping technology, though only available at a limited number of resource-limited setting reference and regional laboratories, but high capital and test costs have limited their wide expansion. Point mutation assays present opportunities for simplified laboratory assays, but HIV genetic variability, extensive codon redundancy at or near the mutation target sites with limited multiplexing capability have restricted their utility. Next-generation sequencing, despite high costs, may have potential to reduce the testing cost significantly through multiplexing in high-throughput facilities, although the level of bioinformatics expertise required for data analysis is currently still complex and expensive and lacks standardization. Web-based genotype-free prediction systems may provide enhanced antiretroviral treatment decision-making without the need for laboratory testing, but require further clinical field evaluation and implementation scientific research in resource-limited settings.

The use of digital games and simulators in veterinary education: an overview with examples.

PubMed

de Bie, M H; Lipman, L J A

2012-01-01

In view of current technological possibilities and the popularity of games, the interest in games for educational purposes is remarkably on the rise. This article outlines the (future) use of (digital) games and simulators in several disciplines, especially in the veterinary curriculum. The different types of game-based learning (GBL)-varying from simple interactive computer board games to more complex virtual simulation strategies-will be discussed as well as the benefits, possibilities, and limitations of the educational use of games. The real breakthrough seems to be a few years away. Technological developments in the future might diminish the limitations and stumbling blocks that currently exist. Consequently, educational games will play a new and increasingly important role in the future veterinary curriculum, providing an attractive and useful way of learning.

Development of mirror coatings for gravitational-wave detectors

NASA Astrophysics Data System (ADS)

Steinlechner, J.

2018-05-01

Gravitational waves are detected by measuring length changes between mirrors in the arms of kilometre-long Michelson interferometers. Brownian thermal noise arising from thermal vibrations of the mirrors can limit the sensitivity to distance changes between the mirrors, and, therefore, the ability to measure gravitational-wave signals. Thermal noise arising from the highly reflective mirror coatings will limit the sensitivity both of current detectors (when they reach design performance) and of planned future detectors. Therefore, the development of coatings with low thermal noise, which at the same time meet strict optical requirements, is of great importance. This article gives an overview of the current status of coatings and of the different approaches for coating improvement. This article is part of a discussion meeting issue `The promises of gravitational-wave astronomy'.

Development of mirror coatings for gravitational-wave detectors.

PubMed

Steinlechner, J

2018-05-28

Gravitational waves are detected by measuring length changes between mirrors in the arms of kilometre-long Michelson interferometers. Brownian thermal noise arising from thermal vibrations of the mirrors can limit the sensitivity to distance changes between the mirrors, and, therefore, the ability to measure gravitational-wave signals. Thermal noise arising from the highly reflective mirror coatings will limit the sensitivity both of current detectors (when they reach design performance) and of planned future detectors. Therefore, the development of coatings with low thermal noise, which at the same time meet strict optical requirements, is of great importance. This article gives an overview of the current status of coatings and of the different approaches for coating improvement.This article is part of a discussion meeting issue 'The promises of gravitational-wave astronomy'. © 2018 The Author(s).

Peer-Delivered Recovery Support Services for Addictions in the United States: A Systematic Review.

PubMed

Bassuk, Ellen L; Hanson, Justine; Greene, R Neil; Richard, Molly; Laudet, Alexandre

2016-04-01

This systematic review identifies, appraises, and summarizes the evidence on the effectiveness of peer-delivered recovery support services for people in recovery from alcohol and drug addiction. Nine studies met criteria for inclusion in the review. They were assessed for quality and outcomes including substance use and recovery-related factors. Despite significant methodological limitations found in the included studies, the body of evidence suggests salutary effects on participants. Current limitations and recommendations for future research are discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

Molecular analysis of breast sentinel lymph nodes.

PubMed

Blumencranz, Peter W; Pieretti, Maura; Allen, Kathleen G; Blumencranz, Lisa E

2011-07-01

Lymphatic mapping and sentinel lymph node (SLN) biopsy have become the standard of care for staging the axilla in patients with invasive breast cancer. Current histologic methods for SLN evaluation have limitations, including subjectivity, limited sensitivity, and lack of standardization. The discovery of molecular markers to detect metastases has been reported over the last 2 decades. The authors review the historical development of these markers and the clinical use of one of the molecular platforms in 478 patients at their institution. Controversies and future directions are discussed. Copyright © 2011 Elsevier Inc. All rights reserved.

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

Rajaguru, S. P.; Antia, H. M., E-mail: rajaguru@iiap.res.in

We present and discuss results from time–distance helioseismic measurements of meridional circulation (MC) in the solar convection zone using 4 yr of Doppler velocity observations by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. Using a built-in mass conservation constraint in terms of the stream function, we invert helioseismic travel times to infer the MC in the solar convection zone. We find that the return flow that closes the MC is possibly beneath the depth of 0.77 R{sub ⊙}. We discuss the significance of this result in relation to other helioseismic inferences published recently and possible reasons for the differences inmore » the results. Our results show clearly the pitfalls involved in the measurements of material flows in the deep solar interior given the current limits on the signal-to-noise ratio and our limited understanding of systematics in the data. We also discuss the implications of our results for the dynamics of solar interior and popular solar dynamo models.« less

Current limitations and recommendations to improve testing ...

EPA Pesticide Factsheets

In this paper existing regulatory frameworks and test systems for assessing potential endocrine-active chemicals are described, and associated challenges discussed, along with proposed approaches to address these challenges. Regulatory frameworks vary somewhat across organizations, but all basically evaluate whether a chemical possesses endocrine activity and whether this activity can result in adverse outcomes either to humans or the environment. Current test systems include in silico, in vitro and in vivo techniques focused on detecting potential endocrine activity, and in vivo tests that collect apical data to detect possible adverse effects. These test systems are currently designed to robustly assess endocrine activity and/or adverse effects in the estrogen, androgen, and thyroid hormonal pathways; however, there are some limitations of current test systems for evaluating endocrine hazard and risk. These limitations include a lack of certainty regarding: 1)adequately sensitive species and life-stages, 2) mechanistic endpoints that are diagnostic for endocrine pathways of concern, and 3) the linkage between mechanistic responses and apical, adverse outcomes. Furthermore, some existing test methods are resource intensive in regard to time, cost, and use of animals. However, based on recent experiences, there are opportunities to improve approaches to, and guidance for existing test methods, and to reduce uncertainty. For example, in vitro high throughput

Clinical Research with Transcranial Direct Current Stimulation (tDCS): Challenges and Future Directions

PubMed Central

Brunoni, Andre Russowsky; Nitsche, Michael A.; Bolognini, Nadia; Bikson, Marom; Wagner, Tim; Merabet, Lotfi; Edwards, Dylan J.; Valero-Cabre, Antoni; Rotenberg, Alexander; Pascual-Leone, Alvaro; Ferrucci, Roberta; Priori, Alberto; Boggio, Paulo; Fregni, Felipe

2011-01-01

Background Transcranial direct current stimulation (tDCS) is a neuromodulatory technique that delivers low-intensity, direct current to cortical areas facilitating or inhibiting spontaneous neuronal activity. In the past ten years, tDCS physiological mechanisms of action have been intensively investigated giving support for the investigation of its applications in clinical neuropsychiatry and rehabilitation. However, new methodological, ethical, and regulatory issues emerge when translating the findings of preclinical and phase I studies into phase II and III clinical studies. The aim of this comprehensive review is to discuss the key challenges of this process and possible methods to address them. Methods We convened a workgroup of researchers in the field to review, discuss and provide updates and key challenges of neuromodulation use for clinical research. Main Findings/Discussion We reviewed several basic and clinical studies in the field and identified potential limitations, taking into account the particularities of the technique. We review and discuss the findings into four topics: (i) mechanisms of action of tDCS, parameters of use and computer-based human brain modeling investigating electric current fields and magnitude induced by tDCS; (ii) methodological aspects related to the clinical research of tDCS as divided according to study phase (i.e., preclinical, phase I, phase II and phase III studies); (iii) ethical and regulatory concerns; (iv) future directions regarding novel approaches, novel devices, and future studies involving tDCS. Finally, we propose some alternative methods to facilitate clinical research on tDCS. PMID:22037126

"Ideal" tearing and the transition to fast reconnection in the weakly collisional MHD and EMHD regimes

NASA Astrophysics Data System (ADS)

Del Sarto, Daniele; Pucci, Fulvia; Tenerani, Anna; Velli, Marco

2016-03-01

This paper discusses the transition to fast growth of the tearing instability in thin current sheets in the collisionless limit where electron inertia drives the reconnection process. It has been previously suggested that in resistive MHD there is a natural maximum aspect ratio (ratio of sheet length and breadth to thickness) which may be reached for current sheets with a macroscopic length L, the limit being provided by the fact that the tearing mode growth time becomes of the same order as the Alfvén time calculated on the macroscopic scale. For current sheets with a smaller aspect ratio than critical the normalized growth rate tends to zero with increasing Lundquist number S, while for current sheets with an aspect ratio greater than critical the growth rate diverges with S. Here we carry out a similar analysis but with electron inertia as the term violating magnetic flux conservation: previously found scalings of critical current sheet aspect ratios with the Lundquist number are generalized to include the dependence on the ratio de2/L2, where de is the electron skin depth, and it is shown that there are limiting scalings which, as in the resistive case, result in reconnecting modes growing on ideal time scales. Finite Larmor radius effects are then included, and the rescaling argument at the basis of "ideal" reconnection is proposed to explain secondary fast reconnection regimes naturally appearing in numerical simulations of current sheet evolution.

Do therapists address gender and power in infidelity? A feminist analysis of the treatment literature.

PubMed

Williams, Kirstee; Knudson-Martin, Carmen

2013-07-01

Sociocontextual factors such as gender and power play an important role in the etiology of affairs and in recovery from them, yet it is unclear how current treatment models address these issues. Drawing on feminist epistemology, this study utilized a grounded theory analysis of 29 scholarly articles and books on infidelity treatment published between 2000 and 2010 to identify the circumstances under which gender and power issues were or were not part of treatment. We found five conditions that limit attention to gender and power: (a) speaking (or assuming) as though partners are equal, (b) reframing infidelity as a relationship problem, (c) limiting discussion of societal context to background, (d) not considering how societal gender and power patterns impact relationship dynamics, and (e) limiting discussion of ethics on how to position around infidelity. Analysis explored how each occurred across three phases of couple therapy. The findings provide a useful foundation for a sociocontextual framework for infidelity treatment. © 2012 American Association for Marriage and Family Therapy.

Genetically Encoded Voltage Indicators: Opportunities and Challenges

PubMed Central

Yang, Helen H.

2016-01-01

A longstanding goal in neuroscience is to understand how spatiotemporal patterns of neuronal electrical activity underlie brain function, from sensory representations to decision making. An emerging technology for monitoring electrical dynamics, voltage imaging using genetically encoded voltage indicators (GEVIs), couples the power of genetics with the advantages of light. Here, we review the properties that determine indicator performance and applicability, discussing both recent progress and technical limitations. We then consider GEVI applications, highlighting studies that have already deployed GEVIs for biological discovery. We also examine which classes of biological questions GEVIs are primed to address and which ones are beyond their current capabilities. As GEVIs are further developed, we anticipate that they will become more broadly used by the neuroscience community to eavesdrop on brain activity with unprecedented spatiotemporal resolution. SIGNIFICANCE STATEMENT Genetically encoded voltage indicators are engineered light-emitting protein sensors that typically report neuronal voltage dynamics as changes in brightness. In this review, we systematically discuss the current state of this emerging method, considering both its advantages and limitations for imaging neural activity. We also present recent applications of this technology and discuss what is feasible now and what we anticipate will become possible with future indicator development. This review will inform neuroscientists of recent progress in the field and help potential users critically evaluate the suitability of genetically encoded voltage indicator imaging to answer their specific biological questions. PMID:27683896

Opportunities to overcome the current limitations and challenges for efficient microbial production of optically pure lactic acid.

PubMed

Abdel-Rahman, Mohamed Ali; Sonomoto, Kenji

2016-10-20

There has been growing interest in the microbial production of optically pure lactic acid due to the increased demand for lactic acid-derived environmentally friendly products, for example biodegradable plastic (poly-lactic acid), as an alternative to petroleum-derived materials. To maximize the market uptake of these products, their cost should be competitive and this could be achieved by decreasing the production cost of the raw material, that is, lactic acid. It is of great importance to isolate and develop robust and highly efficient microbial lactic acid producers. Alongside the fermentative substrate and concentration, the yield and productivity of lactic acid are key parameters and major factors in determining the final production cost of lactic acid. In this review, we will discuss the current limitations and challenges for cost-efficient microbial production of optically pure lactic acid. The main obstacles to effective fermentation are the use of food resources, indirect utilization of polymeric sugars, sensitivity to inhibitory compounds released during biomass treatments, substrate inhibition, decreased lactic acid yield and productivity, inefficient utilization of mixed sugars, end product inhibition, increased use of neutralizing agents, contamination problems, and decreased optical purity of lactic acid. Furthermore, opportunities to address and overcome these limitations, either by fermentation technology or metabolic engineering approaches, will be introduced and discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

'Muscle-sparing' statins: preclinical profiles and future clinical use.

PubMed

Pfefferkorn, Jeffrey A

2009-03-01

Coronary heart disease (CHD) is a leading cause of death in the US, and hypercholesterolemia is a key risk factor for this disease. The current standard of care for treating hypercholesterolemia is the use of HMG-CoA reductase inhibitors, also known as statins, which block the rate-limiting step of cholesterol biosynthesis. In widespread clinical use, statins have proven safe and effective for both primary prevention of CHD and secondary prevention of coronary events. Results from several recent clinical trials have demonstrated that increasingly aggressive cholesterol-lowering therapy might offer additional protection against CHD compared with less aggressive treatment standards. While higher doses of current statin therapies are capable of achieving these more aggressive treatment goals, in certain cases statin-induced myalgia, the muscle pain or weakness that sometimes accompanies high-dose statin therapy, limits patient compliance with a treatment regimen. To address this limitation, efforts have been undertaken to develop highly hepatoselective statins that are capable of delivering best-in-class efficacy with minimized risk of dose-limiting myalgia. In this review, the preclinical and early clinical data for these next generation statins are discussed.

Problems associated with gene transfer and opportunities for microgravity environments

NASA Astrophysics Data System (ADS)

Tennessen, Daniel J.

1997-01-01

The method of crop improvement by gene transfer is becoming increasingly routine with transgenic foods and ornamental crops now being marketed to consumers. However, biological processes of plants, and the physical barriers of current protocols continue to limit the application of gene transfer in many commercial crops. The goal of this paper is to outline the current limitations of gene transfer and to hypothesize possible opportunities for use of microgravity to overcome such limitations. The limitations detailed in this paper include host-range specificity of Agrobacterium mediated transformation, probability of gene insertion, position effects of the inserted genes, gene copy number, stability of foreign gene expression in host plants, and regeneration of recalcitrant plant species. Microgravity offers an opportunity for gene transfer where cell growth kinetics, DNA synthesis, and genetic recombination rates can be altered. Such biological conditions may enhance the ability for recombination of reporter genes and other genes of interest to agriculture. Proposed studies would be useful for understanding instability of foreign gene expression and may lead to stable transformed plants. Other aspects of gene transfer in microgravity are discussed.

A cryogenic scan mechanism for use in Fourier transform spectrometers

NASA Technical Reports Server (NTRS)

Hakun, Claef F.; Blumenstock, Kenneth A.

1995-01-01

This paper describes the requirements, design, assembly and testing of the linear Scan Mechanism (SM) of the Composite Infrared Spectrometer (CIRS) Instrument. The mechanism consists of an over constrained flexible structure, an innovative moving magnet actuator, passive eddy current dampers, a Differential Eddy Current (DEC) sensor, Optical Limit Sensors (OLS), and a launch lock. Although all the components of the mechanism are discussed, the flexible structure and the magnetic components are the primary focus. Several problems encountered and solutions implemented during the development of the scan mechanism are also described.

Bioreactor Engineering of Stem Cell Environments

PubMed Central

Tandon, Nina; Marolt, Darja; Cimetta, Elisa; Vunjak-Novakovic, Gordana

2013-01-01

Stem cells hold promise to revolutionize modern medicine by development of new therapies, disease models and drug screening systems. Standard cell culture systems have limited biological relevance because they do not recapitulate the complex 3-dimensional interactions and biophysical cues that characterize the in vivo environment. In this review, we discuss the current advances in engineering stem cell environments using novel biomaterials and bioreactor technologies. We also reflect on the challenges the field is currently facing with regard to translation of stem cell based therapies into the clinic. PMID:23531529

Phase slip process and charge density wave dynamics in a one dimensional conductor

NASA Astrophysics Data System (ADS)

Habiballah, N.; Zouadi, M.; Arbaoui, A.; Qjani, M.; Dumas, J.

In this paper, we study the phase slip effect on the charge density wave (CDW) dynamics in a one-dimensional conductor in the weak pinning limit. A considerable enhancement of JCDW is observed in the presence of phase slips. In addition, a spatial dependence of the CDW current density JCDW is also studied showing that a decrease of JCDW with distance from the current contact occurs. The results are discussed in terms the relationship between additional phase slips and the mobility of phase dislocations nucleated at electrical contacts.

Current status of matrix-assisted laser desorption ionisation-time of flight mass spectrometry in the clinical microbiology laboratory.

PubMed

Kok, Jen; Chen, Sharon C A; Dwyer, Dominic E; Iredell, Jonathan R

2013-01-01

The integration of matrix-assisted laser desorption ionisation-time of flight mass spectrometry (MALDI-TOF MS) into many clinical microbiology laboratories has revolutionised routine pathogen identification. MALDI-TOF MS complements and has good potential to replace existing phenotypic identification methods. Results are available in a more clinically relevant timeframe, particularly in bacteraemic septic shock. Novel applications include strain typing and the detection of antimicrobial resistance, but these are not widely used. This review discusses the technical aspects, current applications, and limitations of MALDI-TOF MS.

Duality and nonduality in meditation research.

PubMed

Josipovic, Zoran

2010-12-01

The great variety of meditation techniques found in different contemplative traditions presents a challenge when attempting to create taxonomies based on the constructs of contemporary cognitive sciences. In the current issue of Consciousness and Cognition, Travis and Shear add 'automatic self-transcending' to the previously proposed categories of 'focused attention' and 'open monitoring', and suggest characteristic EEG bands as the defining criteria for each of the three categories. Accuracy of current taxonomies and potential limitations of EEG measurements as classifying criteria are discussed. Copyright © 2010 Elsevier Inc. All rights reserved.

REVIEW ARTICLE: Current trends and future requirements for the mass spectrometric investigation of microbial, mammalian and plant metabolomes

NASA Astrophysics Data System (ADS)

Dunn, Warwick B.

2008-03-01

The functional levels of biological cells or organisms can be separated into the genome, transcriptome, proteome and metabolome. Of these the metabolome offers specific advantages to the investigation of the phenotype of biological systems. The investigation of the metabolome (metabolomics) has only recently appeared as a mainstream scientific discipline and is currently developing rapidly for the study of microbial, plant and mammalian metabolomes. The metabolome pipeline or workflow encompasses the processes of sample collection and preparation, collection of analytical data, raw data pre-processing, data analysis and data storage. Of these processes the collection of analytical data will be discussed in this review with specific interest shown in the application of mass spectrometry in the metabolomics pipeline. The current developments in mass spectrometry platforms (GC-MS, LC-MS, DIMS and imaging MS) and applications of specific interest will be highlighted. The current limitations of these platforms and applications will be discussed with areas requiring further development also highlighted. These include the detectable coverage of the metabolome, the identification of metabolites and the process of converting raw data to biological knowledge.

Developments in Coastal Ocean Modeling

NASA Astrophysics Data System (ADS)

Allen, J. S.

2001-12-01

Capabilities in modeling continental shelf flow fields have improved markedly in the last several years. Progress is being made toward the long term scientific goal of utilizing numerical circulation models to interpolate, or extrapolate, necessarily limited field measurements to provide additional full-field information describing the behavior of, and providing dynamical rationalizations for, complex observed coastal flow. The improvement in modeling capabilities has been due to several factors including an increase in computer power and, importantly, an increase in experience of modelers in formulating relevant numerical experiments and in analyzing model results. We demonstrate present modeling capabilities and limitations by discussion of results from recent studies of shelf circulation off Oregon and northern California (joint work with Newberger, Gan, Oke, Pullen, and Wijesekera). Strong interactions between wind-forced coastal currents and continental shelf topography characterize the flow regimes in these cases. Favorable comparisons of model and measured alongshore currents and other variables provide confidence in the model-produced fields. The dependence of the mesoscale circulation, including upwelling and downwelling fronts and flow instabilities, on the submodel used to parameterize the effects of small scale turbulence, is discussed. Analyses of model results to provide explanations for the observed, but previously unexplained, alongshore variability in the intensity of coastal upwelling, which typically results in colder surface water south of capes, and the observed development in some locations of northward currents near the coast in response to the relaxation of southward winds, are presented.

Assessment of Current Process Modeling Approaches to Determine Their Limitations, Applicability and Developments Needed for Long-Fiber Thermoplastic Injection Molded Composites

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

Nguyen, Ba Nghiep; Holbery, Jim; Smith, Mark T.

2006-11-30

This report describes the status of the current process modeling approaches to predict the behavior and flow of fiber-filled thermoplastics under injection molding conditions. Previously, models have been developed to simulate the injection molding of short-fiber thermoplastics, and an as-formed composite part or component can then be predicted that contains a microstructure resulting from the constituents’ material properties and characteristics as well as the processing parameters. Our objective is to assess these models in order to determine their capabilities and limitations, and the developments needed for long-fiber injection-molded thermoplastics (LFTs). First, the concentration regimes are summarized to facilitate the understandingmore » of different types of fiber-fiber interaction that can occur for a given fiber volume fraction. After the formulation of the fiber suspension flow problem and the simplification leading to the Hele-Shaw approach, the interaction mechanisms are discussed. Next, the establishment of the rheological constitutive equation is presented that reflects the coupled flow/orientation nature. The decoupled flow/orientation approach is also discussed which constitutes a good simplification for many applications involving flows in thin cavities. Finally, before outlining the necessary developments for LFTs, some applications of the current orientation model and the so-called modified Folgar-Tucker model are illustrated through the fiber orientation predictions for selected LFT samples.« less

Complex Homology and the Evolution of Nervous Systems

PubMed Central

Liebeskind, Benjamin J.; Hillis, David M.; Zakon, Harold H.; Hofmann, Hans A.

2016-01-01

We examine the complex evolution of animal nervous systems and discuss the ramifications of this complexity for inferring the nature of early animals. Although reconstructing the origins of nervous systems remains a central challenge in biology, and the phenotypic complexity of early animals remains controversial, a compelling picture is emerging. We now know that the nervous system and other key animal innovations contain a large degree of homoplasy, at least on the molecular level. Conflicting hypotheses about early nervous system evolution are due primarily to differences in the interpretation of this homoplasy. We highlight the need for explicit discussion of assumptions and discuss the limitations of current approaches for inferring ancient phenotypic states. PMID:26746806

Nuclear chiral axial currents and applications to few-nucleon systems

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

Baroni, Alessandro

This Thesis is divided into three main parts. The first part discusses basic aspects of chiral effective field theory and the formalism, based on time ordered perturbation theory, used to to derive the nuclear potentials and currents from the chiral Lagrangians. The second part deals with the actual derivation, up to one loop, of the two-nucleon potential and one- and two-nucleon weak axial charge and current. In both derivations ultraviolet divergences generated by loop corrections are isolated using dimensional regularization. The resulting axial current is finite and conserved in the chiral limit, while the axial charge requires renormalization. A completemore » set of contact terms for the axial charge up to the relevant order in the power counting is constructed. The third part of this Thesis discusses two applications: (i) the calculation of the Gamow-Teller matrix element of tritium, used to constrain the single low-energy constant entering the axial current; (ii) the calculation of neutrino-deuteron inclusive cross sections at low energies. These results have confirmed previous predictions obtained in phenomenological approaches. These latter studies have played an important role in the analysis and interpretation of experiments at the Sudbury Neutrino Observatory.« less

Electron current extraction from a permanent magnet waveguide plasma cathode.

PubMed

Weatherford, B R; Foster, J E; Kamhawi, H

2011-09-01

An electron cyclotron resonance plasma produced in a cylindrical waveguide with external permanent magnets was investigated as a possible plasma cathode electron source. The configuration is desirable in that it eliminates the need for a physical antenna inserted into the plasma, the erosion of which limits operating lifetime. Plasma bulk density was found to be overdense in the source. Extraction currents over 4 A were achieved with the device. Measurements of extracted electron currents were similar to calculated currents, which were estimated using Langmuir probe measurements at the plasma cathode orifice and along the length of the external plume. The influence of facility effects and trace ionization in the anode-cathode gap are also discussed. © 2011 American Institute of Physics

Modeling and strain gauging of eddy current repulsion deicing systems

NASA Technical Reports Server (NTRS)

Smith, Samuel O.

1993-01-01

Work described in this paper confirms and extends work done by Zumwalt, et al., on a variety of in-flight deicing systems that use eddy current repulsion for repelling ice. Two such systems are known as electro-impulse deicing (EIDI) and the eddy current repulsion deicing strip (EDS). Mathematical models for these systems are discussed for their capabilities and limitations. The author duplicates a particular model of the EDS. Theoretical voltage, current, and force results are compared directly to experimental results. Dynamic strain measurements results are presented for the EDS system. Dynamic strain measurements near EDS or EIDI coils are complicated by the high magnetic fields in the vicinity of the coils. High magnetic fields induce false voltage signals out of the gages.

The Parity Paradigm: Can Legislation Help Reduce the Cost Burden of Oral Anticancer Medications?

PubMed

Kircher, Sheetal M; Meeker, Caitlin R; Nimeiri, Halla; Geynisman, Daniel M; Zafar, S Yousuf; Shankaran, Veena; de Souza, Jonas; Wong, Yu-Ning

2016-01-01

Over the last decade, there has been increased development and use of oral anticancer medications, which sometimes leads to high cost sharing for patients. Drug parity laws require insurance plans to cover oral anticancer medications with the same cost sharing as intravenous/injected chemotherapy or have a capped limit on out-of-pocket costs. There are currently 36 enacted state laws (plus the District of Columbia) addressing drug parity, but no federal laws. In this policy perspective piece, we discuss the history, opportunities, and limitations of drug parity laws in oncology. We also discuss the implications of provisions of the Affordable Care Act and other proposed policy reforms on financing oral chemotherapy. Copyright © 2016 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Brain-Computer Interfaces Using Sensorimotor Rhythms: Current State and Future Perspectives

PubMed Central

Yuan, Han; He, Bin

2014-01-01

Many studies over the past two decades have shown that people can use brain signals to convey their intent to a computer using brain-computer interfaces (BCIs). BCI systems extract specific features of brain activity and translate them into control signals that drive an output. Recently, a category of BCIs that are built on the rhythmic activity recorded over the sensorimotor cortex, i.e. the sensorimotor rhythm (SMR), has attracted considerable attention among the BCIs that use noninvasive neural recordings, e.g. electroencephalography (EEG), and have demonstrated the capability of multi-dimensional prosthesis control. This article reviews the current state and future perspectives of SMR-based BCI and its clinical applications, in particular focusing on the EEG SMR. The characteristic features of SMR from the human brain are described and their underlying neural sources are discussed. The functional components of SMR-based BCI, together with its current clinical applications are reviewed. Lastly, limitations of SMR-BCIs and future outlooks are also discussed. PMID:24759276

The development and clinical evaluation of second-generation leishmaniasis vaccines.

PubMed

Duthie, Malcolm S; Raman, Vanitha S; Piazza, Franco M; Reed, Steven G

2012-01-05

Infection with Leishmania parasites results in a range of clinical manifestations and outcomes. Control of Leishmania parasite transmission is extremely difficult due to the large number of vectors and potential reservoirs, and none of the current treatments are ideal. Vaccination could be an effective strategy to provide sustained control. In this review, the current global situation with regard to leishmaniasis, the immunology of Leishmania infection and various efforts to identify second generation vaccine candidates are briefly discussed. The variety of clinical trials conducted using the only current second generation vaccine approved for clinical use, LEISH-F1+MPL-SE, are described. Given that epidemiological evidence suggests that reducing the canine reservoir also positively impacts human incidence, efforts at providing a vaccine for leishmaniasis in dogs are highlighted. Finally, potential refinements and surrogate markers that could expedite the introduction of a vaccine that can limit the severity and incidence of leishmaniasis are discussed. Copyright © 2011 Elsevier Ltd. All rights reserved.

A review of mild traumatic brain injury diagnostics: current perspectives, limitations, and emerging technology.

PubMed

Cook, Glen A; Hawley, Jason S

2014-10-01

Mild traumatic brain injury (mTBI) or concussion is a common battlefield and in-garrison injury caused by transmission of mechanical forces to the head. The energy transferred in such events can cause structural and/or functional changes in the brain that manifest as focal neurological, cognitive, or behavioral dysfunction. Current diagnostic criteria for mTBI are highly limited, variable, and based on subjective self-report. The subjective nature of the symptoms, both in quantity and quality, together with their large overlap in other physical and behavioral maladies, limit the clinician's ability to accurately diagnose, treat, and make prognostic decisions after such injuries. These diagnostic challenges are magnified in an operational environment as well. The Department of Defense has invested significant resources into improving the diagnostic tools and accuracy for mTBI. This focus has been to supplement the clinician's examination with technology that is better able to objectify brain dysfunction after mTBI. Through this review, we discuss the current state of three promising technologies--soluble protein biomarkers, advanced neuroimaging, and quantitative electroencephalography--that are of particular interest within military medicine. Reprint & Copyright © 2014 Association of Military Surgeons of the U.S.

Radiation environment and shielding for early manned Mars missions

NASA Technical Reports Server (NTRS)

Hall, Stephen B.; Mccann, Michael E.

1986-01-01

The problem of shielding a crew during early manned Mars missions is discussed. Requirements for shielding are presented in the context of current astronaut exposure limits, natural ionizing radiation sources, and shielding inherent in a particular Mars vehicle configuration. An estimated range for shielding weight is presented based on the worst solar flare dose, mission duration, and inherent vehicle shielding.

Time-dependent interstellar chemistry

NASA Technical Reports Server (NTRS)

Glassgold, A. E.

1985-01-01

Some current problems in interstellar chemistry are considered in the context of time-dependent calculations. The limitations of steady-state models of interstellar gas-phase chemistry are discussed, and attempts to chemically date interstellar clouds are reviewed. The importance of studying the physical and chemical properties of interstellar dust is emphasized. Finally, the results of a series of studies of collapsing clouds are described.

Which Factors Obstruct or Stimulate Teacher Educators to Use ICT Innovatively?

ERIC Educational Resources Information Center

Drent, Marjolein; Meelissen, Martina

2008-01-01

This article discusses the factors which stimulate or limit the innovative use of ICT by teacher educators in the Netherlands. Innovative use of ICT is defined as the use of ICT applications that support the educational objectives based on the needs of the current knowledge society. Explorative path analysis and case studies were used to study the…

Aerophagia and belching after herpes simplex encephalitis.

PubMed

Scheid, Rainer; Teich, Niels; Schroeter, Matthias L

2008-03-01

The etiology of abnormal belching is not known. Currently, it is being subsumed under "functional gastroduodenal disorders." Here, we report the unusual case history of a patient who developed aerophagia and consecutive excessive belching in association with herpes simplex encephalitis. The case report adds to the limited information about potential organic geneses of belching. Implications for possible medical therapies are discussed.

Real-time cartesian force feedback control of a teleoperated robot

NASA Technical Reports Server (NTRS)

Campbell, Perry

1989-01-01

Active cartesian force control of a teleoperated robot is investigated. An economical microcomputer based control method was tested. Limitations are discussed and methods of performance improvement suggested. To demonstrate the performance of this technique, a preliminary test was performed with success. A general purpose bilateral force reflecting hand controller is currently being constructed based on this control method.

Podcasting and Digital Video in the Classroom: A Call for Research

ERIC Educational Resources Information Center

Newman, John H.

2011-01-01

A case is directed at digital immigrants to utilize mobile computing devices such as an Apple iPod to deliver content to students in self-contained special education classrooms. The author discusses the current state of the use of iPods in classrooms, and how research using these devices has been limited to institutions of higher learning, while…

Valuation of Drug Abuse: A Review of Current Methodologies and Implications for Policy Making

ERIC Educational Resources Information Center

Schori, Maayan

2011-01-01

This article reviews the use of several valuation methods as they relate to drug abuse and places them within the context of U.S. policy. First, cost-of-illness (COI) studies are reviewed and their limitations discussed. Second, three additional economic methods of valuing drug abuse are reviewed, including cost-effectiveness analysis (CEA),…

Indicators of University-Industry Knowledge Transfer Performance and Their Implications for Universities: Evidence from the United Kingdom

ERIC Educational Resources Information Center

Rossi, Federica; Rosli, Ainurul

2015-01-01

The issue of what indicators are most appropriate in order to measure the performance of universities in knowledge transfer (KT) activities remains relatively under-investigated. The main aim of this paper is to identify and discuss the limitations to the current measurements of university-industry KT performance, and propose some directions for…

Identifying krill eggs in the central California current using novel multiplex PCR primers: Applications and limitations

NASA Astrophysics Data System (ADS)

Carrion, C. N.; Slesinger, E.; Marinovic, B.

2016-02-01

Euphausiids, otherwise known as krill, are an important link between primary producers and higher trophic levels within the central California current upwelling system. Euphausia pacifica and Thysanoessa spinifera, two of the most common euphausiid species along the central California coast, are both broadcast spawners and have some overlap in habitat, e.g. near marine life hotspots like the Monterey Bay and Gulf of Farallones. Species composition of euphausiid egg population within these regions is currently unknown. Distinct morphological differences between their eggs are lost once the egg dies or is preserved via formalin, alcohol, or freezing. In this project we designed genus specific DNA primers (mtCOI) for use in a multiplex PCR to distinguish among spawned euphausiid eggs of Euphausia spp. and Thysanoessa spp. in central California current surface waters. Effective and ineffective application of primers in a multiplex versus single-plex PCR is discussed, with an emphasis on primer design limitations in reference to the available barcoded regions of mitochondrial cytochrome oxidase subunit I (mtCOI) for each species in GenBank. This new protocol expands current monitoring efforts into sampling a non-swimming portion of the population which has the potential to improve euphausiid biomass estimates.

Reporting nuclear cardiology: a joint position paper by the European Association of Nuclear Medicine (EANM) and the European Association of Cardiovascular Imaging (EACVI).

PubMed

Trägårdh, Elin; Hesse, Birger; Knuuti, Juhani; Flotats, Albert; Kaufmann, Philipp A; Kitsiou, Anastasia; Hacker, Marcus; Verberne, Hein J; Edenbrandt, Lars; Delgado, Victoria; Donal, Erwan; Edvardsen, Thor; Galderisi, Maurizio; Habib, Gilbert; Lancellotti, Patrizio; Nieman, Koen; Rosenhek, Raphael; Agostini, Denis; Gimelli, Alessia; Lindner, Oliver; Slart, Riemert; Ubleis, Christopher

2015-03-01

The report of an imaging procedure is a critical component of an examination, being the final and often the only communication from the interpreting physician to the referring or treating physician. Very limited evidence and few recommendations or guidelines on reporting imaging studies are available; therefore, an European position statement on how to report nuclear cardiology might be useful. The current paper combines the limited existing evidence with expert consensus, previously published recommendations as well as current clinical practices. For all the applications discussed in this paper (myocardial perfusion, viability, innervation, and function as acquired by single photon emission computed tomography and positron emission tomography or hybrid imaging), headings cover laboratory and patient demographics, clinical indication, tracer administration and image acquisition, findings, and conclusion of the report. The statement also discusses recommended terminology in nuclear cardiology, image display, and preliminary reports. It is hoped that this statement may lead to more attention to create well-written and standardized nuclear cardiology reports and eventually lead to improved clinical outcome. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

Injectable Hydrogels for Cardiac Tissue Repair after Myocardial Infarction

PubMed Central

Khattab, Ahmad; Islam, Mohammad Ariful; Hweij, Khaled Abou; Zeitouny, Joya; Waters, Renae; Sayegh, Malek; Hossain, Md Monowar; Paul, Arghya

2015-01-01

Cardiac tissue damage due to myocardial infarction (MI) is one of the leading causes of mortality worldwide. The available treatments of MI include pharmaceutical therapy, medical device implants, and organ transplants, all of which have severe limitations including high invasiveness, scarcity of donor organs, thrombosis or stenosis of devices, immune rejection, and prolonged hospitalization time. Injectable hydrogels have emerged as a promising solution for in situ cardiac tissue repair in infarcted hearts after MI. In this review, an overview of various natural and synthetic hydrogels for potential application as injectable hydrogels in cardiac tissue repair and regeneration is presented. The review starts with brief discussions about the pathology of MI, its current clinical treatments and their limitations, and the emergence of injectable hydrogels as a potential solution for post MI cardiac regeneration. It then summarizes various hydrogels, their compositions, structures and properties for potential application in post MI cardiac repair, and recent advancements in the application of injectable hydrogels in treatment of MI. Finally, the current challenges associated with the clinical application of injectable hydrogels to MI and their potential solutions are discussed to help guide the future research on injectable hydrogels for translational therapeutic applications in regeneration of cardiac tissue after MI. PMID:27668147

Mechanisms of Drug-Resistance in Kinases

PubMed Central

Barouch-Bentov, Rina; Sauer, Karsten

2010-01-01

Introduction Because of their important roles in disease and excellent “druggability”, kinases have become the second-largest drug target family. The great success of the BCR-ABL inhibitor imatinib in treating CML illustrates the high potential of kinase inhibitor (KI) therapeutics, but also unveiled a major limitation: the development of drug-resistance. This is a significant concern as KIs reach large patient populations for an expanding array of indications. Areas covered We provide an up-to-date understanding of the mechanisms through which KIs function, and through which cells can become KI-resistant. We review current and future approaches to overcome KI-resistance, focussing on currently approved KIs and KIs in clinical trials. We then discuss approaches to improve KI efficacy and overcome drug-resistance and novel approaches to develop less drug-resistance prone KI-therapeutics. Expert opinion Although drug-resistance is a concern for current KI-therapeutics, recent progress in our understanding of the underlying mechanisms and promising technological advances may overcome this limitation and provide powerful new therapeutics. PMID:21235428

A nonlinear viscoelastic approach to durability predictions for polymer based composite structures

NASA Technical Reports Server (NTRS)

Brinson, Hal F.

1991-01-01

Current industry approaches for the durability assessment of metallic structures are briefly reviewed. For polymer based composite structures, it is suggested that new approaches must be adopted to include memory or viscoelastic effects which could lead to delayed failures that might not be predicted using current techniques. A durability or accelerated life assessment plan for fiber reinforced plastics (FRP) developed and documented over the last decade or so is reviewed and discussed. Limitations to the plan are outlined and suggestions to remove the limitations are given. These include the development of a finite element code to replace the previously used lamination theory code and the development of new specimen geometries to evaluate delamination failures. The new DCB model is reviewed and results are presented. Finally, it is pointed out that new procedures are needed to determine interfacial properties and current efforts underway to determine such properties are reviewed. Suggestions for additional efforts to develop a consistent and accurate durability predictive approach for FRP structures are outlined.

A nonlinear viscoelastic approach to durability predictions for polymer based composite structures

NASA Technical Reports Server (NTRS)

Brinson, Hal F.; Hiel, C. C.

1990-01-01

Current industry approaches for the durability assessment of metallic structures are briefly reviewed. For polymer based composite structures, it is suggested that new approaches must be adopted to include memory or viscoelastic effects which could lead to delayed failures that might not be predicted using current techniques. A durability or accelerated life assessment plan for fiber reinforced plastics (FRP) developed and documented over the last decade or so is reviewed and discussed. Limitations to the plan are outlined and suggestions to remove the limitations are given. These include the development of a finite element code to replace the previously used lamination theory code and the development of new specimen geometries to evaluate delamination failures. The new DCB model is reviewed and results are presented. Finally, it is pointed out that new procedures are needed to determine interfacial properties and current efforts underway to determine such properties are reviewed. Suggestions for additional efforts to develop a consistent and accurate durability predictive approach for FRP structures is outlined.

Crisis communication: learning from the 1998 LPG near miss in Stockholm.

PubMed

Castenfors, K; Svedin, L

2001-12-14

The authors examine current trends in urban risks and resilience in relation to hazardous material transports in general, and crisis communication and the Stockholm liquefied petroleum gas (LPG) near miss in 1998 in particular. The article discusses how current dynamics affecting urban areas, such as the decay in terms of increased condensation and limited expansion alternatives combined with industry site contamination and transports of hazardous materials on old worn-out physical infrastructure, work together to produce high-risk factors and increase urban vulnerability in large parts of the world today. Crisis communication takes a particularly pronounced role in the article as challenges in communication and confidence maintenance under conditions of information uncertainty and limited information control are explored. The LPG near miss case illustrates a Swedish case of urban risk and the tight coupling to hazardous material transports. The case also serves as a current example of Swedish resilience and lack of preparedness in urban crises, with particular observations and lessons learned in regards to crisis communication.

Mechanical Computing Redux: Limitations at the Nanoscale

NASA Astrophysics Data System (ADS)

Liu, Tsu-Jae King

2014-03-01

Technology solutions for overcoming the energy efficiency limits of nanoscale complementary metal oxide semiconductor (CMOS) technology ultimately will be needed in order to address the growing issue of integrated-circuit chip power density. Off-state leakage current sets a fundamental lower limit in energy per operation for any voltage-level-based digital logic implemented with transistors (CMOS and beyond), which leads to practical limits for device density (i.e. cost) and operating frequency (i.e. system performance). Mechanical switches have zero off-state leakag and hence can overcome this fundamental limit. Contact adhesive force sets a lower limit for the switching energy of a mechanical switch, however, and also directly impacts its performance. This paper will review recent progress toward the development of nano-electro-mechanical relay technology and discuss remaining challenges for realizing the promise of mechanical computing for ultra-low-power computing. Supported by the Center for Energy Efficient Electronics Science (NSF Award 0939514).

Development of biosensors for the detection of biological warfare agents: its issues and challenges.

PubMed

Kumar, Harish; Rani, Renu

2013-01-01

This review discusses current development in biosensors for the detection of biological warfare agents (BWAs). BWAs include bacteria, virus and toxins that are added deliberately into air water and food to spread terrorism and cause disease or death. The rapid and unambiguous detection and identification of BWAs with early warning signals for detecting possible biological attack is a major challenge for government agencies particularly military and health. The detection devices--biosensors--can be classified (according to their physicochemical transducers) into four types: electrochemical, nucleic acid, optical and piezoelectric. Advantages and limitations of biosensors are discussed in this review followed by an assessment of the current state of development of different types of biosensors. The research and development in biosensors for biological warfare agent detection is of great interest for the public as well as for governments.

Hydrogels for Engineering of Perfusable Vascular Networks

PubMed Central

Liu, Juan; Zheng, Huaiyuan; Poh, Patrina S. P.; Machens, Hans-Günther; Schilling, Arndt F.

2015-01-01

Hydrogels are commonly used biomaterials for tissue engineering. With their high-water content, good biocompatibility and biodegradability they resemble the natural extracellular environment and have been widely used as scaffolds for 3D cell culture and studies of cell biology. The possible size of such hydrogel constructs with embedded cells is limited by the cellular demand for oxygen and nutrients. For the fabrication of large and complex tissue constructs, vascular structures become necessary within the hydrogels to supply the encapsulated cells. In this review, we discuss the types of hydrogels that are currently used for the fabrication of constructs with embedded vascular networks, the key properties of hydrogels needed for this purpose and current techniques to engineer perfusable vascular structures into these hydrogels. We then discuss directions for future research aimed at engineering of vascularized tissue for implantation. PMID:26184185

State medical marijuana laws: understanding the laws and their limitations.

PubMed

Pacula, Rosalie Liccardo; Chriqui, Jamie F; Reichmann, Deborah A; Terry-McElrath, Yvonne M

2002-01-01

Significant attention has been given to the debate regarding allowances for medical marijuana use since the 1996 California and Arizona ballot initiatives. State medical marijuana allowances, however, have existed since the mid-1970s. Much of the current debate stems from confusion about the various ways states approach the issue. In this paper, we present original legal research on current state medical marijuana laws identifying four different ways states statutorily enable the medical use of marijuana. We discuss the tension these approaches have with federal law as well as their implications regarding real access for patients. In addition, we present information on how a small number of states are trying to deal with the issue of access within the context of their medical marijuana laws, and discuss the implication of various supply approaches on the enforcement of other state marijuana laws.

The European nanometrology landscape.

PubMed

Leach, Richard K; Boyd, Robert; Burke, Theresa; Danzebrink, Hans-Ulrich; Dirscherl, Kai; Dziomba, Thorsten; Gee, Mark; Koenders, Ludger; Morazzani, Valérie; Pidduck, Allan; Roy, Debdulal; Unger, Wolfgang E S; Yacoot, Andrew

2011-02-11

This review paper summarizes the European nanometrology landscape from a technical perspective. Dimensional and chemical nanometrology are discussed first as they underpin many of the developments in other areas of nanometrology. Applications for the measurement of thin film parameters are followed by two of the most widely relevant families of functional properties: measurement of mechanical and electrical properties at the nanoscale. Nanostructured materials and surfaces, which are seen as key materials areas having specific metrology challenges, are covered next. The final section describes biological nanometrology, which is perhaps the most interdisciplinary applications area, and presents unique challenges. Within each area, a review is provided of current status, the capabilities and limitations of current techniques and instruments, and future directions being driven by emerging industrial measurement requirements. Issues of traceability, standardization, national and international programmes, regulation and skills development will be discussed in a future paper.

The European nanometrology landscape

NASA Astrophysics Data System (ADS)

Leach, Richard K.; Boyd, Robert; Burke, Theresa; Danzebrink, Hans-Ulrich; Dirscherl, Kai; Dziomba, Thorsten; Gee, Mark; Koenders, Ludger; Morazzani, Valérie; Pidduck, Allan; Roy, Debdulal; Unger, Wolfgang E. S.; Yacoot, Andrew

2011-02-01

This review paper summarizes the European nanometrology landscape from a technical perspective. Dimensional and chemical nanometrology are discussed first as they underpin many of the developments in other areas of nanometrology. Applications for the measurement of thin film parameters are followed by two of the most widely relevant families of functional properties: measurement of mechanical and electrical properties at the nanoscale. Nanostructured materials and surfaces, which are seen as key materials areas having specific metrology challenges, are covered next. The final section describes biological nanometrology, which is perhaps the most interdisciplinary applications area, and presents unique challenges. Within each area, a review is provided of current status, the capabilities and limitations of current techniques and instruments, and future directions being driven by emerging industrial measurement requirements. Issues of traceability, standardization, national and international programmes, regulation and skills development will be discussed in a future paper.

Estimating debt capacity of New York State Health facilities.

PubMed

Hogan, A J

1985-01-01

A measure of the capacity to take on new debt is developed for health facilities. This measure is a function of the current financial position of the facility, future financial market conditions (interest rates and bond/loan maturities), and a policy variable (the debt service coverage ratio) to be set by state health policy makers. The quality of this measure was shown to depend on the quality of current health facility financial accounting data, on the quality of forecasts of interest rates and future cashflow, and on the appropriateness of the criterion debt service coverage ratio. Some of the limitations of the estimate are discussed. Consideration of the debt capacity estimate serves to highlight some crucial issues in imposing capital expenditure limits, namely the interrelationships between financial viability, interest rates and access to capital markets.

Systems biology coupled with label-free high-throughput detection as a novel approach for diagnosis of chronic obstructive pulmonary disease

PubMed Central

Richens, Joanna L; Urbanowicz, Richard A; Lunt, Elizabeth AM; Metcalf, Rebecca; Corne, Jonathan; Fairclough, Lucy; O'Shea, Paul

2009-01-01

Chronic obstructive pulmonary disease (COPD) is a treatable and preventable disease state, characterised by progressive airflow limitation that is not fully reversible. Although COPD is primarily a disease of the lungs there is now an appreciation that many of the manifestations of disease are outside the lung, leading to the notion that COPD is a systemic disease. Currently, diagnosis of COPD relies on largely descriptive measures to enable classification, such as symptoms and lung function. Here the limitations of existing diagnostic strategies of COPD are discussed and systems biology approaches to diagnosis that build upon current molecular knowledge of the disease are described. These approaches rely on new 'label-free' sensing technologies, such as high-throughput surface plasmon resonance (SPR), that we also describe. PMID:19386108

Transplantation of Bioprinted Tissues and Organs: Technical and Clinical Challenges and Future Perspectives.

PubMed

Ravnic, Dino J; Leberfinger, Ashley N; Koduru, Srinivas V; Hospodiuk, Monika; Moncal, Kazim K; Datta, Pallab; Dey, Madhuri; Rizk, Elias; Ozbolat, Ibrahim T

2017-07-01

: Three-dimensional (3D) bioprinting is a revolutionary technology in building living tissues and organs with precise anatomic control and cellular composition. Despite the great progress in bioprinting research, there has yet to be any clinical translation due to current limitations in building human-scale constructs, which are vascularized and readily implantable. In this article, we review the current limitations and challenges in 3D bioprinting, including in situ techniques, which are one of several clinical translational models to facilitate the application of this technology from bench to bedside. A detailed discussion is made on the technical barriers in the fabrication of scalable constructs that are vascularized, autologous, functional, implantable, cost-effective, and ethically feasible. Clinical considerations for implantable bioprinted tissues are further expounded toward the correction of end-stage organ dysfunction and composite tissue deficits.

Toward a new generation of agricultural system data, models, and knowledge products: State of agricultural systems science.

PubMed

Jones, James W; Antle, John M; Basso, Bruno; Boote, Kenneth J; Conant, Richard T; Foster, Ian; Godfray, H Charles J; Herrero, Mario; Howitt, Richard E; Janssen, Sander; Keating, Brian A; Munoz-Carpena, Rafael; Porter, Cheryl H; Rosenzweig, Cynthia; Wheeler, Tim R

2017-07-01

We review the current state of agricultural systems science, focusing in particular on the capabilities and limitations of agricultural systems models. We discuss the state of models relative to five different Use Cases spanning field, farm, landscape, regional, and global spatial scales and engaging questions in past, current, and future time periods. Contributions from multiple disciplines have made major advances relevant to a wide range of agricultural system model applications at various spatial and temporal scales. Although current agricultural systems models have features that are needed for the Use Cases, we found that all of them have limitations and need to be improved. We identified common limitations across all Use Cases, namely 1) a scarcity of data for developing, evaluating, and applying agricultural system models and 2) inadequate knowledge systems that effectively communicate model results to society. We argue that these limitations are greater obstacles to progress than gaps in conceptual theory or available methods for using system models. New initiatives on open data show promise for addressing the data problem, but there also needs to be a cultural change among agricultural researchers to ensure that data for addressing the range of Use Cases are available for future model improvements and applications. We conclude that multiple platforms and multiple models are needed for model applications for different purposes. The Use Cases provide a useful framework for considering capabilities and limitations of existing models and data.

Critical current simulation in granular superconductors above the percolation threshold

NASA Astrophysics Data System (ADS)

Riedinger, Roland

1992-02-01

In the phase-coherent regime without applied external magnetic field, the critical superconducting current is limited by intragranular junctions which behave like Josephson junctions. We study the percolation aspects specific to lattices of such junctions and/or the mixing of superconductor with normal grains by averaging over configurations. We illustrate on 2 and 3 dimensional examples. The power laws valid near the percolation threshold are valid well above it, in two and three dimensions. We discuss the other models limiting the superconducting current, the vortex creep and superconducting order parameter fluctuations. Dans la limite de champ magnétique nul et de cohérence de phase du paramètre d'ordre supraconducteur, le courant supraconducteur maximal dans un réseau est limité par les jonctions intergranulaires qui se comportent comme des jonctions Josephson. Nous analysons les problèmes de percolation spécifiques aux réseaux de jonctions et du mélange de grains normaux et supraconducteurs. Nous donnons des exemples bidimensionnels et tridimensionnels ; après moyenne sur les configurations et analyse en taille finie, nous montrons que les lois de puissance valables au voisinage du seuil de percolation s'étendent sur un grand domaine au-delà du seuil de percolation, à deux et trois dimensions. Nous discutons les autres modèles limitant le courant supraconducteur, ancrage de vortex et fluctuations du paramètre d'ordre.

Toward a New Generation of Agricultural System Data, Models, and Knowledge Products: State of Agricultural Systems Science

NASA Technical Reports Server (NTRS)

Jones, James W.; Antle, John M.; Basso, Bruno; Boote, Kenneth J.; Conant, Richard T.; Foster, Ian; Godfray, H. Charles J.; Herrero, Mario; Howitt, Richard E.; Janssen, Sander;

Toward a new generation of agricultural system data, models, and knowledge products: State of agricultural systems science

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

Jones, James W.; Antle, John M.; Basso, Bruno

We review the current state of agricultural systems science, focusing in particular on the capabilities and limitations of agricultural systems models. We discuss the state of models relative to five different Use Cases spanning field, farm, landscape, regional, and global spatial scales and engaging questions in past, current, and future time periods. Contributions from multiple disciplines have made major advances relevant to a wide range of agricultural system model applications at various spatial and temporal scales. Although current agricultural systems models have features that are needed for the Use Cases, we found that all of them have limitations and needmore » to be improved. We identified common limitations across all Use Cases, namely 1) a scarcity of data for developing, evaluating, and applying agricultural system models and 2) inadequate knowledge systems that effectively communicate model results to society. We argue that these limitations are greater obstacles to progress than gaps in conceptual theory or available methods for using system models. New initiatives on open data show promise for addressing the data problem, but there also needs to be a cultural change among agricultural researchers to ensure that data for addressing the range of Use Cases are available for future model improvements and applications. We conclude that multiple platforms and multiple models are needed for model applications for different purposes. The Use Cases provide a useful framework for considering capabilities and limitations of existing models and data.« less

Improving colorectal cancer screening: fact and fantasy

NASA Astrophysics Data System (ADS)

Van Dam, Jacques

2008-02-01

Premalignant diseases of the gastrointestinal tract, such as Barrett's esophagus, long-standing ulcerative colitis, and adenomatous polyps, have a significantly increased risk for development of adenocarcinoma, most often through an intermediate stage of dysplasia. Adenocarcinoma of the colon is the second most common cancer in the United States. Because patients with colorectal cancer often present with advanced disease, the outcomes are associated with significant morbidity and mortality. Effective methods of early detection are essential. As non-polypoid dysplasia is not visible using conventional endoscopy, surveillance of patients with Barrett's esophagus and ulcerative colitis is performed via a system in which multiple random biopsies are obtained at prescribed intervals. Sampling error and missed diagnoses occur frequently and render current screening methods inadequate. Also, the examination of a tissue biopsy is time consuming and costly, and significant intra- and inter-observer variation may occur. The newer methods discussed herein demonstrate the potential to solve these problems by early detection of disease with high sensitivity and specificity. Conventional endoscopy is based on the observation of white light reflected off the tissue surface. Subtle changes in color and shadow reveal structural changes. New developments in optical imaging go beyond white light, exploiting other properties of light. Several promising methods will be discussed at this meeting and shall be briefly discussed below. However, few such imaging modalities have arrived at our clinical practice. Some much more practical methods to improve colorectal cancer screening are currently being evaluated for their clinical impact. These methods seek to overcome limitations other than those of detecting dysplasia not visible under white light endoscopy. The current standard practice of colorectal cancer screening utilizes colonoscopy, an uncomfortable, sometimes difficult medical procedure. Efforts to improve the practice of colonoscopy will be described. Another limitation of the current practice is the inability to detect polypoid neoplasia that is hidden from view under white light imaging by the natural folds that occur within the colon. A device to overcome this limitation will also be described. Efforts to improve colorectal cancer screening (and thereby decrease the death rate of this second leading cause of cancer death in the United States) are progressing in many arenas. The researcher, basic or clinical, should maintain an up to date overview of the field and how each new technological advance is likely to have a role in the screening and early detection of colorectal cancer.

Impact of future fuel properties on aircraft engines and fuel systems

NASA Technical Reports Server (NTRS)

Rudey, R. A.; Grobman, J. S.

1978-01-01

The effect of modifications in hydrocarbon jet fuels specifications on engine performance, component durability and maintenance, and aircraft fuel system performance is discussed. Specific topics covered include: specific fuel consumption; ignition at relight limits; exhaust emissions; combustor liner temperatures; carbon deposition; gum formation in fuel nozzles, erosion and corrosion of turbine blades and vanes; deposits in fuel system heat exchangers; and pumpability and flowability of the fuel. Data that evaluate the ability of current technology aircraft to accept fuel specification changes are presented, and selected technological advances that can reduce the severity of the problems are described and discussed.

An overview of the energy situation

NASA Technical Reports Server (NTRS)

Pitts, D. R.

1978-01-01

Beginning with a historical review of the domestic pattern of energy usage, the current dependence of the United States upon dwindling petroleum resources is examined. The possible limit of petroleum usage is discussed, and recent oil production trends are presented. Coupling these with projected analyses of OPEC oil productive capability in the early 1980's indicates a serious worldwide as well as American energy problem in the next decade. The need for conservation and rapid development of application of alternative energy resources is discussed including quantitative projections of significant conservation efforts as well as estimates of domestic alternative energy resource capabilities.

A real-time MPEG software decoder using a portable message-passing library

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

Kwong, Man Kam; Tang, P.T. Peter; Lin, Biquan

1995-12-31

We present a real-time MPEG software decoder that uses message-passing libraries such as MPL, p4 and MPI. The parallel MPEG decoder currently runs on the IBM SP system but can be easil ported to other parallel machines. This paper discusses our parallel MPEG decoding algorithm as well as the parallel programming environment under which it uses. Several technical issues are discussed, including balancing of decoding speed, memory limitation, 1/0 capacities, and optimization of MPEG decoding components. This project shows that a real-time portable software MPEG decoder is feasible in a general-purpose parallel machine.

Progress toward the development of an aircraft icing analysis capability

NASA Technical Reports Server (NTRS)

Shaw, R. J.

1984-01-01

An overview of the NASA efforts to develop an aircraft icing analysis capability is presented. Discussions are included of the overall and long term objectives of the program as well as current capabilities and limitations of the various computer codes being developed. Descriptions are given of codes being developed to analyze two and three dimensional trajectories of water droplets, airfoil ice accretion, aerodynamic performance degradation of components and complete aircraft configurations, electrothermal deicer, and fluid freezing point depressant deicer. The need for bench mark and verification data to support the code development is also discussed.

Imaging detectors and electronics—a view of the future

NASA Astrophysics Data System (ADS)

Spieler, Helmuth

2004-09-01

Imaging sensors and readout electronics have made tremendous strides in the past two decades. The application of modern semiconductor fabrication techniques and the introduction of customized monolithic integrated circuits have made large-scale imaging systems routine in high-energy physics. This technology is now finding its way into other areas, such as space missions, synchrotron light sources, and medical imaging. I review current developments and discuss the promise and limits of new technologies. Several detector systems are described as examples of future trends. The discussion emphasizes semiconductor detector systems, but I also include recent developments for large-scale superconducting detector arrays.

Pilot workload and fatigue: A critical survey of concepts and assessment techniques

NASA Technical Reports Server (NTRS)

Gartner, W. B.; Murphy, M. R.

1976-01-01

The principal unresolved issues in conceptualizing and measuring pilot workload and fatigue are discussed. These issues are seen as limiting the development of more useful working concepts and techniques and their application to systems engineering and management activities. A conceptual analysis of pilot workload and fatigue, an overview and critique of approaches to the assessment of these phenomena, and a discussion of current trends in the management of unwanted workload and fatigue effects are presented. Refinements and innovations in assessment methods are recommended for enhancing the practical significance of workload and fatigue studies.

Mass spectrometry based proteomics profiling as diagnostic tool in oncology: current status and future perspective.

PubMed

Findeisen, Peter; Neumaier, Michael

2009-01-01

Proteomics analysis has been heralded as a novel tool for identifying new and specific biomarkers that may improve diagnosis and monitoring of various disease states. Recent years have brought a number of proteomics profiling technologies. Although proteomics profiling has resulted in the detection of disease-associated differences and modification of proteins, current proteomics technologies display certain limitations that are hampering the introduction of these new technologies into clinical laboratory diagnostics and routine applications. In this review, we summarize current advances in mass spectrometry based biomarker discovery. The promises and challenges of this new technology are discussed with particular emphasis on diagnostic perspectives of mass-spectrometry based proteomics profiling for malignant diseases.

Objectives and metrics for wildlife monitoring

USGS Publications Warehouse

Sauer, J.R.; Knutson, M.G.

2008-01-01

Monitoring surveys allow managers to document system status and provide the quantitative basis for management decision-making, and large amounts of effort and funding are devoted to monitoring. Still, monitoring surveys often fall short of providing required information; inadequacies exist in survey designs, analyses procedures, or in the ability to integrate the information into an appropriate evaluation of management actions. We describe current uses of monitoring data, provide our perspective on the value and limitations of current approaches to monitoring, and set the stage for 3 papers that discuss current goals and implementation of monitoring programs. These papers were derived from presentations at a symposium at The Wildlife Society's 13th Annual Conference in Anchorage, Alaska, USA. [2006

Construction of testing facilities and verifying tests of a 22.9 kV/630 A class superconducting fault current limiter

NASA Astrophysics Data System (ADS)

Yim, S.-W.; Yu, S.-D.; Kim, H.-R.; Kim, M.-J.; Park, C.-R.; Yang, S.-E.; Kim, W.-S.; Hyun, O.-B.; Sim, J.; Park, K.-B.; Oh, I.-S.

2010-11-01

We have constructed and completed the preparation for a long-term operation test of a superconducting fault current limiter (SFCL) in a Korea Electric Power Corporation (KEPCO) test grid. The SFCL with rating of 22.9 kV/630 A, 3-phases, has been connected to the 22.9 kV test grid equipped with reclosers and other protection devices in Gochang Power Testing Center of KEPCO. The main goals of the test are the verification of SFCL performance and protection coordination studies. A line-commutation type SFCL was fabricated and installed for this project, and the superconducting components were cooled by a cryo-cooler to 77 K in the sub-cooled liquid nitrogen pressurized by 3 bar of helium gas. The verification test includes un-manned - long-term operation with and without loads and fault tests. Since the test site is 170 km away from the laboratory, we will adopt the un-manned operation with real-time remote monitoring and controlling using high speed internet. For the fault tests, we will apply fault currents up to around 8 kArms to the SFCL using an artificial fault generator. The fault tests may allow us not only to confirm the current limiting capability of the SFCL, but also to adjust the SFCL - recloser coordination such as resetting over-current relay parameters. This paper describes the construction of the testing facilities and discusses the plans for the verification tests.

The American Science Pipeline: Sustaining Innovation in a Time of Economic Crisis

PubMed Central

Hue, Gillian; Sales, Jessica; Comeau, Dawn; Lynn, David G.

2010-01-01

Significant limitations have emerged in America's science training pipeline, including inaccessibility, inflexibility, financial limitations, and lack of diversity. We present three effective programs that collectively address these challenges. The programs are grounded in rigorous science and integrate through diverse disciplines across undergraduate, graduate, and postdoctoral students, and resonate with the broader community. We discuss these models in the context of current economic constraints on higher education and the urgent need for our institutions to recruit and retain diverse student populations and sustain the successful American record in scientific education and innovation. PMID:21123689

Cavity Enhanced Absorption Spectroscopy using a Prism Cavity and Supercontinuum Source

NASA Astrophysics Data System (ADS)

Lehmann, Kevin K.; Johnston, Paul S.

2010-03-01

The multiplex advantage of current cavity enhanced spectrometers is limited by the limited high reflectivity bandwidth of the dielectric mirrors used to construct the high finesse cavity. We report on our development of a spectrometer that uses Brewster's angle retroreflectors that is excited with supercontinuum radiation generated by a 1.06 μm pumped photonic crystal fiber, which covers the 500-1800 nm spectral range. Recent progress will be discussed including modeling of the prism cavity losses, alternative prism materials for use in the UV and mid-IR, and a new higher power source pumped by a mode-locked laser.

Cathode limited charge transport and performance of thin-film rechargeable lithium batteries

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

Bates, J.B.; Hart, F.X.; Lubben, D.

1994-11-01

Several types of thin-film rechargeable batteries based on lithium metal anodes and amorphous V{sub 2}O{sub 5} (aV{sub 2}O{sub 5}), LiMn{sub 2}O{sub 4}, and LiCoO{sub 2} cathodes have been investigated in this laboratory. In all cases, the current density of these cells is limited by lithium ion transport in the cathodes. This paper, discusses sources of this impedance in Li-aV{sub 2}O{sub 5} and Li-LiMn{sub 2}O{sub 4} thin-film cells and their effect on cell performance.

Miniature in vivo robotics and novel robotic surgical platforms.

PubMed

Shah, Bhavin C; Buettner, Shelby L; Lehman, Amy C; Farritor, Shane M; Oleynikov, Dmitry

2009-05-01

Robotic surgical systems, such as the da Vinci Surgical System (Intuitive Surgical, Inc., Sunnyvale, California), have revolutionized laparoscopic surgery but are limited by large size, increased costs, and limitations in imaging. Miniature in vivo robots are being developed that are inserted entirely into the peritoneal cavity for laparoscopic and natural orifice transluminal endoscopic surgical (NOTES) procedures. In the future, miniature camera robots and microrobots should be able to provide a mobile viewing platform. This article discusses the current state of miniature robotics and novel robotic surgical platforms and the development of future robotic technology for general surgery and urology.

Supermarket sales data: feasibility and applicability in population food and nutrition monitoring.

PubMed

Tin, Sandar Tin; Mhurchu, Cliona Ni; Bullen, Chris

2007-01-01

Population food and nutrition monitoring plays a critical role in understanding suboptimal nutrition at the population level, yet current monitoring methods such as national surveys are not practical to undertake on a continuous basis. Supermarket sales data potentially address this gap by providing detailed, timely, and inexpensive monitoring data for informing policies and anticipating trends. This paper reviews 22 studies that used supermarket sales data to examine food purchasing patterns. Despite some methodological limitations, feasibility studies showed promising results. The potential and limitations of using supermarket sales data to supplement food and nutrition monitoring methods are discussed.

Nonequilibrium optical conductivity: General theory and application to transient phases

NASA Astrophysics Data System (ADS)

Kennes, D. M.; Wilner, E. Y.; Reichman, D. R.; Millis, A. J.

2017-08-01

A nonequilibrium theory of optical conductivity of dirty-limit superconductors and commensurate charge density wave is presented. We discuss the current response to different experimentally relevant light-field probe pulses and show that a single frequency definition of the optical conductivity σ (ω )≡j (ω )/E (ω ) is difficult to interpret out of the adiabatic limit. We identify characteristic time-domain signatures distinguishing between superconducting, normal-metal, and charge density wave states. We also suggest a route to directly address the instantaneous superfluid stiffness of a superconductor by shaping the probe light field.

Power flow analysis and optimal locations of resistive type superconducting fault current limiters.

PubMed

Zhang, Xiuchang; Ruiz, Harold S; Geng, Jianzhao; Shen, Boyang; Fu, Lin; Zhang, Heng; Coombs, Tim A

2016-01-01

Based on conventional approaches for the integration of resistive-type superconducting fault current limiters (SFCLs) on electric distribution networks, SFCL models largely rely on the insertion of a step or exponential resistance that is determined by a predefined quenching time. In this paper, we expand the scope of the aforementioned models by considering the actual behaviour of an SFCL in terms of the temperature dynamic power-law dependence between the electrical field and the current density, characteristic of high temperature superconductors. Our results are compared to the step-resistance models for the sake of discussion and clarity of the conclusions. Both SFCL models were integrated into a power system model built based on the UK power standard, to study the impact of these protection strategies on the performance of the overall electricity network. As a representative renewable energy source, a 90 MVA wind farm was considered for the simulations. Three fault conditions were simulated, and the figures for the fault current reduction predicted by both fault current limiting models have been compared in terms of multiple current measuring points and allocation strategies. Consequently, we have shown that the incorporation of the E - J characteristics and thermal properties of the superconductor at the simulation level of electric power systems, is crucial for estimations of reliability and determining the optimal locations of resistive type SFCLs in distributed power networks. Our results may help decision making by distribution network operators regarding investment and promotion of SFCL technologies, as it is possible to determine the maximum number of SFCLs necessary to protect against different fault conditions at multiple locations.

Using Language Sampling in Clinical Assessments with Bilingual Children: Challenges and Future Directions

PubMed Central

Gutiérrez-Clellen, Vera F.; Simon-Cereijido, Gabriela

2012-01-01

Current language tests designed to assess Spanish-English-speaking children have limited clinical accuracy and do not provide sufficient information to plan language intervention. In contrast, spontaneous language samples obtained in the two languages can help identify language impairment with higher accuracy. In this article, we describe several diagnostic indicators that can be used in language assessments based on spontaneous language samples. First, based on previous research with monolingual and bilingual English speakers, we show that a verb morphology composite measure in combination with a measure of mean length of utterance (MLU) can provide valuable diagnostic information for English development in bilingual children. Dialectal considerations are discussed. Second, we discuss the available research with bilingual Spanish speakers and show a series of procedures to be used for the analysis of Spanish samples: (a) limited MLU and proportional use of ungrammatical utterances; (b) limited grammatical accuracy on articles, verbs, and clitic pronouns; and (c) limited MLU, omission of theme arguments, and limited use of ditransitive verbs. Third, we illustrate the analysis of verb argument structure using a rubric as an assessment tool. Estimated scores on morphological and syntactic measures are expected to increase the sensitivity of clinical assessments with young bilingual children. Further research using other measures of language will be needed for older school-age children. PMID:19851951

Towards Limits on Neutrino Mixing Parameters from Nucleosynthesis in the Big Bang and Supernovae

NASA Astrophysics Data System (ADS)

Cardall, Christian Young

1997-11-01

Astrophysical environments can often provide stricter limits on neutrino mass and mixing parameters than terrestrial experiments. However, before firm limits can be found, there must be confidence in the understanding of the astrophysical environment being used to make these limits. In this dissertation, progress towards limits on neutrino mixing parameters from big bang nucleosynthesis and supernova r-process nucleosynthesis is sought. By way of assessment of current knowledge of neutrino oscillation parameters, we examine the potential for a 'natural' three-neutrino mixing scheme (one without sterile neutrinos) to satisfy available data and astrophysical arguments. A small parameter space currently exists for a natural three-neutrino oscillation solution meeting known constraints. If such a solution is ruled out, and current hints about neutrino oscillations are confirmed, mixing between active and sterile neutrinos will probably be required. Because mixing between active and sterile neutrinos with parameters appropriate for the atmospheric or solar neutrino problems increases the primordial 4He abundance, big bang nucleosynthesis considerations can place limits on such mixing. In the present work the overall consistency of standard big bang nucleosynthesis is discussed in light of recent discordant determinations of the primordial deuterium abundance. Cosmological considerations favor a larger baryon density, which supports the lower reported value of D/H. Studies of limits on active-sterile neutrino mixing derived from big bang nucleosynthesis considerations are here extended to consider the dependance of these constraints on the primordial deuterium abundance. If the neutrino-heated ejecta in the post-core-bounce supernova environment is the site of r-process nucleosynthesis, limits can be placed on mixing between νe, and νsbμ, or νsbτ. Refined limits will require a better understanding of this r-process environment, since current supernova models do not show a completely successful r-process. In this work it is shown that general relativistic effects associated with a more compact supernova core can provide more suitable conditions for the r-process. As a step towards analyzing the effects of neutrino mixing in such a relativistic environment, neutrino oscillations in curved spacetime are studied.

Transmitter And Receiver Design For Microwave Fiber Optic Links

NASA Astrophysics Data System (ADS)

Blauvelt, H.; Yen, H.

1984-11-01

Optical fibers are an attractive media for transmitting microwave signals due to their low attenuation, light weight, immunity from electromagnetic interference and large bandwidth capabilities. In this paper, transmitter and receiver components for microwave fiber optic links are reviewed. Current limitations to link signal to noise imposed by the performance of these components are analyzed and promising trends in component development are discussed.

Eta Carinae and Other Luminous Blue Variables

NASA Technical Reports Server (NTRS)

Corcoran, M. F.

2006-01-01

Luminous Blue Variables (LBVs) are believed to be evolved, extremely massive stars close to the Eddington Limit and hence prone to bouts of large-scale, unstable mass loss. I discuss current understanding of the evolutionary state of these objects, the role duplicity may play and known physical characteristics of these stars using the X-ray luminous LBVs Eta Carinae and HD 5980 as test cases.

Web 2.0 and Second Language Learning: What Does the Research Tell Us?

ERIC Educational Resources Information Center

Wang, Shenggao; Vasquez, Camilla

2012-01-01

This article reviews current research on the use of Web 2.0 technologies in second language (L2) learning. Its purpose is to investigate the theoretical perspectives framing it, to identify some of the benefits of using Web 2.0 technologies in L2 learning, and to discuss some of the limitations. The review reveals that blogs and wikis have been…

Probabilistic Approaches to Examining Linguistic Features of Test Items and Their Effect on the Performance of English Language Learners

ERIC Educational Resources Information Center

Solano-Flores, Guillermo

2014-01-01

This article addresses validity and fairness in the testing of English language learners (ELLs)--students in the United States who are developing English as a second language. It discusses limitations of current approaches to examining the linguistic features of items and their effect on the performance of ELL students. The article submits that…

Fictional privacy among Facebook users.

PubMed

Lemieux, Robert

2012-08-01

The current study involved the creation of a fictional Facebook account with limited information and was designed to assess whether participants would accept the friendship of an ambiguous, unknown person. Results indicated that 325 Facebook members (72% of the sample) willingly accepted the friendship of the unknown individual. Results are discussed in relation to privacy concerns, norms of reciprocity, and allowing access to potentially embarrassing information and/or pictures.

Conversion and Retrievability of Hard Copy and Digital Documents on Optical Disks

DTIC Science & Technology

1992-03-01

53 B. CURRENT THESIS PREPARATION TOOLS . ....... 54 1. Thesis Preparation using G-Thesis ..... 55 2. Thesis Preparation using Framemaker ...School mainframe. • Computer Science department students can use a software package called Framemaker , available on Sun work stations in their...by most thesis typists and students. For this reason, the discussion of thesis preparation tools will be limited to; G-thesis, Framemaker and

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

MAEZAWA,Y.; AOKI, S.; EJIRI, S.

The authors report the current status of the systematic studies of the QCD thermodynamics by lattice QCD simulations with two flavors of improved Wilson quarks. They evaluate the critical temperature of two flavor QCD in the chiral limit at zero chemical potential and show the preliminary result. Also they discuss fluctuations at none-zero temperature and density by calculating the quark number and isospin susceptibilities and their derivatives with respect to chemical potential.

Vacuum pumps and systems: A review of current practice

NASA Technical Reports Server (NTRS)

Giles, Stuart

1986-01-01

A review of the fundamental characteristics of the many types of vacuum pumps and vacuum pumping systems is given. The optimum pumping range, relative cost, performance limitations, maintenance problems, system operating costs and similar subjects are discussed. Experiences from the thin film deposition, chemical processing, material handling, food processing and other industries, as well as space simulation are used to support conclusions and recommendations.

Review of modern double beta decay experiments

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

Barabash, A. S., E-mail: barabash@itep.ru

2015-10-28

The review of modern experiments on search and studying of double beta decay processes is done. Results of the most sensitive current experiments are discussed. The main attention is paid to EXO-200, KamLAND-Zen, GERDA-I and CUORE-0 experiments. Modern values of T{sub 1/2}(2ν) and best present limits on neutrinoless double beta decay and double beta decay with Majoron emission are presented. Conservative limits on effective mass of a Majorana neutrino (〈m{sub ν}〉 < 0.46 eV) and a coupling constant of Majoron to neutrino (〈g{sub ee}〉 < 1.3 · 10{sup −5}) are obtained. Prospects of search for neutrinoless double beta decay inmore » new experiments with sensitivity to 〈m{sub ν}〉 at the level of ∼ 0.01-0.1 eV are discussed.« less

The use and limitations of attachment theory in child psychotherapy.

PubMed

Zilberstein, Karen

2014-03-01

Attachment theory and research has proliferated in recent years, spawning new ideas and applications to child therapy. Some of those interventions are creative and useful and rest on solid theory and research, whereas others derive from tenuous assumptions. As an important developmental construct, attachment plays a role in every therapy, but defining that role can be difficult. Therapists must recognize the significance of attachment in treatment but not at the expense of recognizing and treating other issues. This article provides an overview of attachment theory and attachment-based interventions and discusses how to apply those constructs to therapeutic work with children. It reviews attachment theory, assessment, and treatments, and discusses how attachment-focused interventions can be combined with other therapeutic needs and methods. It also considers limitations in the current clinical application of attachment and makes recommendations for further research. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

Indirectly pumped 3.7 THz InGaAs/InAlAs quantum-cascade lasers grown by metal-organic vapor-phase epitaxy.

PubMed

Fujita, Kazuue; Yamanishi, Masamichi; Furuta, Shinichi; Tanaka, Kazunori; Edamura, Tadataka; Kubis, Tillmann; Klimeck, Gerhard

2012-08-27

Device-performances of 3.7 THz indirect-pumping quantum-cascade lasers are demonstrated in an InGaAs/InAlAs material system grown by metal-organic vapor-phase epitaxy. The lasers show a low threshold-current-density of ~420 A/cm2 and a peak output power of ~8 mW at 7 K, no sign of parasitic currents with recourse to well-designed coupled-well injectors in the indirect pump scheme, and a maximum operating temperature of Tmax ~100 K. The observed roll-over of output intensities in current ranges below maximum currents and limitation of Tmax are discussed with a model for electron-gas heating in injectors. Possible ways toward elevation of Tmax are suggested.

Genetically Encoded Voltage Indicators: Opportunities and Challenges.

PubMed

Yang, Helen H; St-Pierre, François

2016-09-28

A longstanding goal in neuroscience is to understand how spatiotemporal patterns of neuronal electrical activity underlie brain function, from sensory representations to decision making. An emerging technology for monitoring electrical dynamics, voltage imaging using genetically encoded voltage indicators (GEVIs), couples the power of genetics with the advantages of light. Here, we review the properties that determine indicator performance and applicability, discussing both recent progress and technical limitations. We then consider GEVI applications, highlighting studies that have already deployed GEVIs for biological discovery. We also examine which classes of biological questions GEVIs are primed to address and which ones are beyond their current capabilities. As GEVIs are further developed, we anticipate that they will become more broadly used by the neuroscience community to eavesdrop on brain activity with unprecedented spatiotemporal resolution. Genetically encoded voltage indicators are engineered light-emitting protein sensors that typically report neuronal voltage dynamics as changes in brightness. In this review, we systematically discuss the current state of this emerging method, considering both its advantages and limitations for imaging neural activity. We also present recent applications of this technology and discuss what is feasible now and what we anticipate will become possible with future indicator development. This review will inform neuroscientists of recent progress in the field and help potential users critically evaluate the suitability of genetically encoded voltage indicator imaging to answer their specific biological questions. Copyright © 2016 the authors 0270-6474/16/369977-13$15.00/0.

Review: New Vaccine Against Tuberculosis: Current Developments and Future Challenges

NASA Astrophysics Data System (ADS)

Liu, Jun

2009-04-01

Tuberculosis (TB) continues to be a global health threat. BCG was developed as an attenuated live vaccine for tuberculosis control nearly a century ago. Despite being the most widely used vaccine in human history, BCG is not an ideal vaccine and has two major limitations: its poor efficacy against adult pulmonary TB and its disconcerting safety in immunocompromised individuals. A safer and more effective TB vaccine is urgently needed. This review article discusses current strategies to develop the next generation of TB vaccines to replace BCG. While some progresses have been made in the past decade, significant challenges lie ahead.

Development and current applications of assisted fertilization.

PubMed

Palermo, Gianpiero D; Neri, Queenie V; Monahan, Devin; Kocent, Justin; Rosenwaks, Zev

2012-02-01

Since the very early establishment of in vitro insemination, it became clear that one of the limiting steps is the achievement of fertilization. Among the different assisted fertilization methods, intracytoplasmic sperm injection emerged as the ultimate technique to allow fertilization with ejaculated, epididymal, and testicular spermatozoa. This work describes the early steps that brought forth the development of intracytoplasmic sperm injection and its role in assisted reproductive techniques. The current methods to select the preferential male gamete will be elucidated and the concerns related to the offspring of severe male factor couples will be discussed. Copyright © 2012. Published by Elsevier Inc.

Bioreactor engineering of stem cell environments.

PubMed

Tandon, Nina; Marolt, Darja; Cimetta, Elisa; Vunjak-Novakovic, Gordana

2013-11-15

Stem cells hold promise to revolutionize modern medicine by the development of new therapies, disease models and drug screening systems. Standard cell culture systems have limited biological relevance because they do not recapitulate the complex 3-dimensional interactions and biophysical cues that characterize the in vivo environment. In this review, we discuss the current advances in engineering stem cell environments using novel biomaterials and bioreactor technologies. We also reflect on the challenges the field is currently facing with regard to the translation of stem cell based therapies into the clinic. Copyright © 2013 Elsevier Inc. All rights reserved.

Placebo Analgesia in Rodents: Current and Future Research

PubMed Central

Keller, Asaf; Akintola, Titilola; Colloca, Luana

2018-01-01

The investigation of placebo effects in animal pain models has received less attention than human research. This may be related to a number of difficulties, including the fact that animals lack the ability to use language and establish expectancies verbally, that animals cannot report and rate the extent to which they experience pain, and the inadequacy of current models of pain. Here, we describe the relatively small number of studies that have been published, communicating the opportunities and excitement of this research. We critically discuss pitfalls and limitations with the hope that this will advance future animal placebo-related research. PMID:29681320

Neuronavigation in the surgical management of brain tumors: current and future trends

PubMed Central

Orringer, Daniel A; Golby, Alexandra; Jolesz, Ferenc

2013-01-01

Neuronavigation has become an ubiquitous tool in the surgical management of brain tumors. This review describes the use and limitations of current neuronavigational systems for brain tumor biopsy and resection. Methods for integrating intraoperative imaging into neuronavigational datasets developed to address the diminishing accuracy of positional information that occurs over the course of brain tumor resection are discussed. In addition, the process of integration of functional MRI and tractography into navigational models is reviewed. Finally, emerging concepts and future challenges relating to the development and implementation of experimental imaging technologies in the navigational environment are explored. PMID:23116076

High-resolution mass spectrometry in toxicology: current status and future perspectives.

PubMed

Maurer, H H; Meyer, Markus R

2016-09-01

This paper reviews high-resolution mass spectrometry (HRMS) approaches using time-of-flight or Orbitrap techniques for research and application in various toxicology fields, particularly in clinical toxicology and forensic toxicology published since 2013 and referenced in PubMed. In the introduction, an overview on applications of HRMS in various toxicology fields is given with reference to current review articles. Papers concerning HRMS in metabolism, screening, and quantification of pharmaceuticals, drugs of abuse, and toxins in human body samples are critically reviewed. Finally, a discussion on advantages as well as limitations and future perspectives of these methods is included.

A review of Soviet plasma engine development

NASA Technical Reports Server (NTRS)

Barnett, John W.

1990-01-01

The Soviet Union has maintained a substantial and successful electric propulsion research and development effort since the 1950s; however, American researchers are generally unfamiliar with the Soviet accomplishments. Sources of information about Soviet electric propulsion research are noted. The development of plasma engines, a subset of the electric propulsion effort, is reviewed using numerous Soviet sources. The operational principles and status of several engines of the closed electron drift and high-current types are discussed. With recognition of the limited knowledge of the current Soviet program, the Soviet and American programs are compared, revealing some differences in program formulation and emphasis.

Challenges in Building Disease-Based National Health Accounts

PubMed Central

Rosen, Allison B.; Cutler, David M.

2012-01-01

Background Measuring spending on diseases is critical to assessing the value of medical care. Objective To review the current state of cost of illness (COI) estimation methods, identifying their strengths, limitations and uses. We briefly describe the current National Health Expenditure Accounts (NHEA), and then go on to discuss the addition of COI estimation to the NHEA. Conclusion Recommendations are made for future research aimed at identifying the best methods for developing and using disease-based national health accounts to optimize the information available to policymakers as they struggle with difficult resource allocation decisions. PMID:19536017

Clinically Relevant Physical Benefits of Exercise Interventions in Breast Cancer Survivors.

PubMed

Kirkham, Amy A; Bland, Kelcey A; Sayyari, Sarah; Campbell, Kristin L; Davis, Margot K

2016-02-01

Evidence is currently limited for the effect of exercise on breast cancer clinical outcomes. However, several of the reported physical benefits of exercise, including peak oxygen consumption, functional capacity, muscle strength and lean mass, cardiovascular risk factors, and bone health, have established associations with disability, cardiovascular disease risk, morbidity, and mortality. This review will summarize the clinically relevant physical benefits of exercise interventions in breast cancer survivors and discuss recommendations for achieving these benefits. It will also describe potential differences in intervention delivery that may impact outcomes and, lastly, describe current physical activity guidelines for cancer survivors.

A NOAA/SWPC Perspective on Space Weather Forecasts That Fail

NASA Astrophysics Data System (ADS)

Biesecker, D. A.

2014-12-01

The Space Weather Prediction Center (SWPC) at NOAA is the Official US source for space weather watches, warning and alerts. These alerts are provided to a breadth of customers covering a range of industries, including electric utilities, airlines, emergency managers, and users of precision GPS to name a few. This talk will review the current tools used by SWPC to forecast geomagnetic storms, solar flares, and solar energetic particle events and present the SWPC performance in each of these areas. We will include a discussion of the current limitations and examples of events that proved difficult to forecast.

Near infrared fluorescence for image-guided surgery

PubMed Central

2012-01-01

Near infrared (NIR) image-guided surgery holds great promise for improved surgical outcomes. A number of NIR image-guided surgical systems are currently in preclinical and clinical development with a few approved for limited clinical use. In order to wield the full power of NIR image-guided surgery, clinically available tissue and disease specific NIR fluorophores with high signal to background ratio are necessary. In the current review, the status of NIR image-guided surgery is discussed along with the desired chemical and biological properties of NIR fluorophores. Lastly, tissue and disease targeting strategies for NIR fluorophores are reviewed. PMID:23256079

Complex Homology and the Evolution of Nervous Systems.

PubMed

Liebeskind, Benjamin J; Hillis, David M; Zakon, Harold H; Hofmann, Hans A

2016-02-01

We examine the complex evolution of animal nervous systems and discuss the ramifications of this complexity for inferring the nature of early animals. Although reconstructing the origins of nervous systems remains a central challenge in biology, and the phenotypic complexity of early animals remains controversial, a compelling picture is emerging. We now know that the nervous system and other key animal innovations contain a large degree of homoplasy, at least on the molecular level. Conflicting hypotheses about early nervous system evolution are due primarily to differences in the interpretation of this homoplasy. We highlight the need for explicit discussion of assumptions and discuss the limitations of current approaches for inferring ancient phenotypic states. Copyright © 2015. Published by Elsevier Ltd.

What is behind the priority heuristic? A mathematical analysis and comment on Brandstätter, Gigerenzer, and Hertwig (2006).

PubMed

Rieger, Marc Oliver; Wang, Mei

2008-01-01

Comments on the article by E. Brandstätter, G. Gigerenzer, and R. Hertwig. The authors discuss the priority heuristic, a recent model for decisions under risk. They reanalyze the experimental validity of this approach and discuss how these results compare with cumulative prospect theory, the currently most established model in behavioral economics. They also discuss how general models for decisions under risk based on a heuristic approach can be understood mathematically to gain some insight in their limitations. They finally consider whether the priority heuristic model can lead to some understanding of the decision process of individuals or whether it is better seen as an as-if model. (c) 2008 APA, all rights reserved

Very Massive Stars in the local Universe

NASA Astrophysics Data System (ADS)

Vink, Jorick S.; Heger, Alexander; Krumholz, Mark R.; Puls, Joachim; Banerjee, S.; Castro, N.; Chen, K.-J.; Chenè, A.-N.; Crowther, P. A.; Daminelli, A.; Gräfener, G.; Groh, J. H.; Hamann, W.-R.; Heap, S.; Herrero, A.; Kaper, L.; Najarro, F.; Oskinova, L. M.; Roman-Lopes, A.; Rosen, A.; Sander, A.; Shirazi, M.; Sugawara, Y.; Tramper, F.; Vanbeveren, D.; Voss, R.; Wofford, A.; Zhang, Y.

2015-03-01

Recent studies have claimed the existence of very massive stars (VMS) up to 300 M ⊙ in the local Universe. As this finding may represent a paradigm shift for the canonical stellar upper-mass limit of 150 M ⊙, it is timely to discuss the status of the data, as well as the far-reaching implications of such objects. We held a Joint Discussion at the General Assembly in Beijing to discuss (i) the determination of the current masses of the most massive stars, (ii) the formation of VMS, (iii) their mass loss, and (iv) their evolution and final fate. The prime aim was to reach broad consensus between observers and theorists on how to identify and quantify the dominant physical processes.

Risk Importance Measures in the Designand Operation of Nuclear Power Plants

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

Vrbanic I.; Samanta P.; Basic, I

This monograph presents and discusses risk importance measures as quantified by the probabilistic risk assessment (PRA) models of nuclear power plants (NPPs) developed according to the current standards and practices. Usually, PRA tools calculate risk importance measures related to a single ?basic event? representing particular failure mode. This is, then, reflected in many current PRA applications. The monograph focuses on the concept of ?component-level? importance measures that take into account different failure modes of the component including common-cause failures (CCFs). In opening sections the roleof risk assessment in safety analysis of an NPP is introduced and discussion given of ?traditional?,more » mainly deterministic, design principles which have been established to assign a level of importance to a particular system, structure or component. This is followed by an overview of main risk importance measures for risk increase and risk decrease from current PRAs. Basic relations which exist among the measures are shown. Some of the current practical applications of risk importancemeasures from the field of NPP design, operation and regulation are discussed. The core of the monograph provides a discussion on theoreticalbackground and practical aspects of main risk importance measures at the level of ?component? as modeled in a PRA, starting from the simplest case, single basic event, and going toward more complexcases with multiple basic events and involvements in CCF groups. The intent is to express the component-level importance measures via theimportance measures and probabilities of the underlying single basic events, which are the inputs readily available from a PRA model andits results. Formulas are derived and discussed for some typical cases. The formulas and their results are demonstrated through some practicalexamples, done by means of a simplified PRA model developed in and run by RiskSpectrum? tool, which are presented in the appendices. The monograph concludes with discussion of limitations of the use of risk importance measures and a summary of component-level importance cases evaluated.« less

HZETRN: A heavy ion/nucleon transport code for space radiations

NASA Technical Reports Server (NTRS)

Wilson, John W.; Chun, Sang Y.; Badavi, Forooz F.; Townsend, Lawrence W.; Lamkin, Stanley L.

1991-01-01

The galactic heavy ion transport code (GCRTRN) and the nucleon transport code (BRYNTRN) are integrated into a code package (HZETRN). The code package is computer efficient and capable of operating in an engineering design environment for manned deep space mission studies. The nuclear data set used by the code is discussed including current limitations. Although the heavy ion nuclear cross sections are assumed constant, the nucleon-nuclear cross sections of BRYNTRN with full energy dependence are used. The relation of the final code to the Boltzmann equation is discussed in the context of simplifying assumptions. Error generation and propagation is discussed, and comparison is made with simplified analytic solutions to test numerical accuracy of the final results. A brief discussion of biological issues and their impact on fundamental developments in shielding technology is given.

Current approaches for the assessment of in situ biodegradation.

PubMed

Bombach, Petra; Richnow, Hans H; Kästner, Matthias; Fischer, Anko

2010-04-01

Considering the high costs and technical difficulties associated with conventional remediation strategies, in situ biodegradation has become a promising approach for cleaning up contaminated aquifers. To verify if in situ biodegradation of organic contaminants is taking place at a contaminated site and to determine if these processes are efficient enough to replace conventional cleanup technologies, a comprehensive characterization of site-specific biodegradation processes is essential. In recent years, several strategies including geochemical analyses, microbial and molecular methods, tracer tests, metabolite analysis, compound-specific isotope analysis, and in situ microcosms have been developed to investigate the relevance of biodegradation processes for cleaning up contaminated aquifers. In this review, we outline current approaches for the assessment of in situ biodegradation and discuss their potential and limitations. We also discuss the benefits of research strategies combining complementary methods to gain a more comprehensive understanding of the complex hydrogeological and microbial interactions governing contaminant biodegradation in the field.

UNITY: Confronting Supernova Cosmology's Statistical and Systematic Uncertainties in a Unified Bayesian Framework

NASA Astrophysics Data System (ADS)

Rubin, D.; Aldering, G.; Barbary, K.; Boone, K.; Chappell, G.; Currie, M.; Deustua, S.; Fagrelius, P.; Fruchter, A.; Hayden, B.; Lidman, C.; Nordin, J.; Perlmutter, S.; Saunders, C.; Sofiatti, C.; Supernova Cosmology Project, The

2015-11-01

While recent supernova (SN) cosmology research has benefited from improved measurements, current analysis approaches are not statistically optimal and will prove insufficient for future surveys. This paper discusses the limitations of current SN cosmological analyses in treating outliers, selection effects, shape- and color-standardization relations, unexplained dispersion, and heterogeneous observations. We present a new Bayesian framework, called UNITY (Unified Nonlinear Inference for Type-Ia cosmologY), that incorporates significant improvements in our ability to confront these effects. We apply the framework to real SN observations and demonstrate smaller statistical and systematic uncertainties. We verify earlier results that SNe Ia require nonlinear shape and color standardizations, but we now include these nonlinear relations in a statistically well-justified way. This analysis was primarily performed blinded, in that the basic framework was first validated on simulated data before transitioning to real data. We also discuss possible extensions of the method.

Trans-oral robotic surgery in oropharyngeal carcinoma - A guide for general practitioners and patients.

PubMed

Liu, Wendy Sijia; Limmer, Alex; Jabbour, Joe; Clark, Jonathan

Trans-oral robotic surgery (TORS) is emerging as a minimally invasive alternative to open surgery, or trans-oral laser surgery, for the treatment of some head and neck pathologies, particularly oropharyngeal carcinoma, which is rapidly increasing in incidence. In this article we review current evidence regarding the use of TORS in head and neck surgery in a manner relevant to general practice. This information may be used to facilitate discussion with patients. Compared with open surgery or trans-oral laser surgery, TORS has numerous advantages, including no scarring, less blood loss, fewer complications, lower rates of admission to the intensive care unit, and reduced length of hospitalisation. The availability of TORS in Australia is currently limited and, therefore, public awareness about TORS is lacking. Details regarding the role of TORS and reliable, up-to-date, patient-friendly information sources are discussed in this article.

Design and optimization of photovoltaics recycling infrastructure.

PubMed

Choi, Jun-Ki; Fthenakis, Vasilis

2010-11-15

With the growing production and installation of photovoltaics (PV) around the world constrained by the limited availability of resources, end-of-life management of PV is becoming very important. A few major PV manufacturers currently are operating several PV recycling technologies at the process level. The management of the total recycling infrastructure, including reverse-logistics planning, is being started in Europe. In this paper, we overview the current status of photovoltaics recycling planning and discuss our mathematic modeling of the economic feasibility and the environmental viability of several PV recycling infrastructure scenarios in Germany; our findings suggest the optimum locations of the anticipated PV take-back centers. Short-term 5-10 year planning for PV manufacturing scraps is the focus of this article. Although we discuss the German situation, we expect the generic model will be applicable to any region, such as the whole of Europe and the United States.

Oral vaccination of fish: Lessons from humans and veterinary species.

PubMed

Embregts, Carmen W E; Forlenza, Maria

2016-11-01

The limited number of oral vaccines currently approved for use in humans and veterinary species clearly illustrates that development of efficacious and safe oral vaccines has been a challenge not only for fish immunologists. The insufficient efficacy of oral vaccines is partly due to antigen breakdown in the harsh gastric environment, but also to the high tolerogenic gut environment and to inadequate vaccine design. In this review we discuss current approaches used to develop oral vaccines for mass vaccination of farmed fish species. Furthermore, using various examples from the human and veterinary vaccine development, we propose additional approaches to fish vaccine design also considering recent advances in fish mucosal immunology and novel molecular tools. Finally, we discuss the pros and cons of using the zebrafish as a pre-screening animal model to potentially speed up vaccine design and testing for aquaculture fish species. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Is it wrong to deliberately conceive or give birth to a child with mental retardation?

PubMed

Vehmas, Simo

2002-02-01

This paper discusses the issues of deciding to have a child with mental retardation, and of terminating a pregnancy when the future child is known to have the same disability. I discuss these problems by criticizing a utilitarian argument, namely, that one should act in a way that results in less suffering and less limited opportunity in the world. My argument is that future parents ought to assume a strong responsibility towards the well-being of their prospective children when they decide to reproduce. The moral point in cases in which our acts affect the well-being of future children should be expressed strictly in terms of parents' culpability. Future children thus do not have current moral standing but presently living persons have current obligations to consider the presumable effects of their actions on future people. I will also argue that there are morally significant differences between 'selective contraception' and selective abortion.

Radiation Effects on Current Field Programmable Technologies

NASA Technical Reports Server (NTRS)

Katz, R.; LaBel, K.; Wang, J. J.; Cronquist, B.; Koga, R.; Penzin, S.; Swift, G.

1997-01-01

Manufacturers of field programmable gate arrays (FPGAS) take different technological and architectural approaches that directly affect radiation performance. Similar y technological and architectural features are used in related technologies such as programmable substrates and quick-turn application specific integrated circuits (ASICs). After analyzing current technologies and architectures and their radiation-effects implications, this paper includes extensive test data quantifying various devices total dose and single event susceptibilities, including performance degradation effects and temporary or permanent re-configuration faults. Test results will concentrate on recent technologies being used in space flight electronic systems and those being developed for use in the near term. This paper will provide the first extensive study of various configuration memories used in programmable devices. Radiation performance limits and their impacts will be discussed for each design. In addition, the interplay between device scaling, process, bias voltage, design, and architecture will be explored. Lastly, areas of ongoing research will be discussed.

The antimicrobial activity of nanoparticles: present situation and prospects for the future

PubMed Central

Wang, Linlin; Hu, Chen; Shao, Longquan

2017-01-01

Nanoparticles (NPs) are increasingly used to target bacteria as an alternative to antibiotics. Nanotechnology may be particularly advantageous in treating bacterial infections. Examples include the utilization of NPs in antibacterial coatings for implantable devices and medicinal materials to prevent infection and promote wound healing, in antibiotic delivery systems to treat disease, in bacterial detection systems to generate microbial diagnostics, and in antibacterial vaccines to control bacterial infections. The antibacterial mechanisms of NPs are poorly understood, but the currently accepted mechanisms include oxidative stress induction, metal ion release, and non-oxidative mechanisms. The multiple simultaneous mechanisms of action against microbes would require multiple simultaneous gene mutations in the same bacterial cell for antibacterial resistance to develop; therefore, it is difficult for bacterial cells to become resistant to NPs. In this review, we discuss the antibacterial mechanisms of NPs against bacteria and the factors that are involved. The limitations of current research are also discussed. PMID:28243086

Canonical Structure and Orthogonality of Forces and Currents in Irreversible Markov Chains

NASA Astrophysics Data System (ADS)

Kaiser, Marcus; Jack, Robert L.; Zimmer, Johannes

2018-03-01

We discuss a canonical structure that provides a unifying description of dynamical large deviations for irreversible finite state Markov chains (continuous time), Onsager theory, and Macroscopic Fluctuation Theory (MFT). For Markov chains, this theory involves a non-linear relation between probability currents and their conjugate forces. Within this framework, we show how the forces can be split into two components, which are orthogonal to each other, in a generalised sense. This splitting allows a decomposition of the pathwise rate function into three terms, which have physical interpretations in terms of dissipation and convergence to equilibrium. Similar decompositions hold for rate functions at level 2 and level 2.5. These results clarify how bounds on entropy production and fluctuation theorems emerge from the underlying dynamical rules. We discuss how these results for Markov chains are related to similar structures within MFT, which describes hydrodynamic limits of such microscopic models.

A Review of the Fatigue Properties of Additively Manufactured Ti-6Al-4V

NASA Astrophysics Data System (ADS)

Cao, Fei; Zhang, Tiantian; Ryder, Matthew A.; Lados, Diana A.

2018-03-01

Various additive manufacturing (AM) technologies have been used to fabricate Ti-6Al-4V. The fatigue performance of Ti-6Al-4V varies from process to process. In this review, fatigue properties of Ti-6Al-4V alloys made by different AM technologies and post-fabrication treatments were compiled and discussed to correlate with the materials' characteristic features, primarily surface roughness and porosity. Microstructure anisotropy and porosity effects on fatigue crack growth and fatigue life are also presented and discussed. A modified Kitagawa-Takahashi diagram developed from current available fatigue data was used to quantify the influence of defects on fatigue strength. This review aims to assist in selecting/optimizing AM processes to achieve high fatigue resistance in Ti-6Al-4V, as well as provide a better understanding of the advantages and limitations of current AM techniques in producing titanium alloys.

Cornering natural SUSY at LHC Run II and beyond

NASA Astrophysics Data System (ADS)

Buckley, Matthew R.; Feld, David; Macaluso, Sebastian; Monteux, Angelo; Shih, David

2017-08-01

We derive the latest constraints on various simplified models of natural SUSY with light higgsinos, stops and gluinos, using a detailed and comprehensive reinterpretation of the most recent 13 TeV ATLAS and CMS searches with ˜ 15 fb-1 of data. We discuss the implications of these constraints for fine-tuning of the electroweak scale. While the most "vanilla" version of SUSY (the MSSM with R-parity and flavor-degenerate sfermions) with 10% fine-tuning is ruled out by the current constraints, models with decoupled valence squarks or reduced missing energy can still be fully natural. However, in all of these models, the mediation scale must be extremely low ( <100 TeV). We conclude by considering the prospects for the high-luminosity LHC era, where we expect the current limits on particle masses to improve by up to ˜ 1 TeV, and discuss further model-building directions for natural SUSY that are motivated by this work.

Feasibility of self-structured current accessed bubble devices in spacecraft recording systems

NASA Technical Reports Server (NTRS)

Nelson, G. L.; Krahn, D. R.; Dean, R. H.; Paul, M. C.; Lo, D. S.; Amundsen, D. L.; Stein, G. A.

1985-01-01

The self-structured, current aperture approach to magnetic bubble memory is described. Key results include: (1) demonstration that self-structured bubbles (a lattice of strongly interacting bubbles) will slip by one another in a storage loop at spacings of 2.5 bubble diameters, (2) the ability of self-structured bubbles to move past international fabrication defects (missing apertures) in the propagation conductors (defeat tolerance), and (3) moving bubbles at mobility limited speeds. Milled barriers in the epitaxial garnet are discussed for containment of the bubble lattice. Experimental work on input/output tracks, storage loops, gates, generators, and magneto-resistive detectors for a prototype device are discussed. Potential final device architectures are described with modeling of power consumption, data rates, and access times. Appendices compare the self-structured bubble memory from the device and system perspectives with other non-volatile memory technologies.

Genetics, biometrics and the informatization of the body.

PubMed

van der Ploeg, Irma

2007-01-01

"Genetics" is a term covering a wide set of theories, practices, and technologies, only some of which overlap with the practices and technologies of biometrics. In this paper some current technological developments relating to biometric applications of genetics will be highlighted. Next, the author will elaborate the notion of the informatization of the body, by means of a brief philosophical detour on the dualisms of language and reality, words and things. In the subsequent sections she will then draw out some of the questions relevant to the purposes of Biometrics Identification Technology Ethics (BITE), and discuss the ethical problems associated with the informatization of the body. There are, however some problems and limitations to the currently dominant ethical discourse to deal with all things ethical in relation to information technology in general, and biometrics or genetics in particular. The final section will discuss some of these meta-problems.

The safety of ezetimibe and simvastatin combination for the treatment of hypercholesterolemia.

PubMed

Kei, Anastazia A; Filippatos, Theodosios D; Elisaf, Moses S

2016-01-01

In the light of the most recent and stricter dyslipidemia treatment guidelines, the need for combination hypolipidemic therapy is increasing. Ezetimibe plus simvastatin is available as a fixed dose therapy offering an efficient hypolipidemic treatment choice. Based on the positive results of the IMProved Reduction of Outcomes: Vytorin Efficacy International Trial (IMPROVE-IT) trial, the use of this drug combination is expected to increase in the next years. This review discusses the current evidence regarding the safety of ezetimibe/simvastatin combination. Current evidence regarding possible associated side effects (musculoskeletal, gastrointestinal, endocrine, hematological, renal, ophthalmologic, allergic, malignancy) and drug interactions of this combination is thoroughly discussed. Ezetimibe and simvastatin treatment, either as a single pill or the combined use of the individual compounds, offers limited additional risk compared with simvastatin monotherapy and comprises a safe and efficient choice for dyslipidemia treatment in high-risk and diabetic patients.

Minimally invasive computer-assisted stereotactic fenestration of an aqueductal cyst: case report.

PubMed

Fonoff, E T; Gentil, A F; Padilha, P M; Teixeira, M J

2010-02-01

Current advances in frame modeling and computer software allow stereotactic procedures to be performed with great accuracy and minimal risk of neural tissue or vascular injury. In this report we associate a previously described minimally invasive stereotactic technique with state-of-the-art 3D computer guidance technology to successfully treat a 55-year-old patient with an arachnoidal cyst obstructing the aqueduct of Sylvius. We provide detailed technical information and discuss how this technique deals with previous limitations for stereotactic manipulation of the aqueductal region. We further discuss current advances in neuroendoscopy for treating obstructive hydrocephalus and make comparisons with our proposed technique. We advocate that this technique is not only capable of treating this pathology but it also has the advantages to enable reestablishment of physiological CSF flow thus preventing future brainstem compression by cyst enlargement. (c) Georg Thieme Verlag KG Stuttgart . New York.

Design of a multimedia gateway for mobile devices

NASA Astrophysics Data System (ADS)

Hens, Raf; Goeminne, Nico; Van Hoecke, Sofie; Verdickt, Tom; Bouve, Thomas; Gielen, Frank; Demeester, Piet

2005-03-01

Although mobile users are currently offered a lot more capabilities on their mobile devices, they still experience some limitations. They can surf the Internet, read their e-mail and receive MMS messages, but they have limited processing power, storage capacity and bandwidth and are limited in their access to peripherals (e.g. printers). We have designed and implemented a multimedia gateway for mobile devices that reduces these limitations. It gives the mobile devices transparent access to high capacity devices connected to the gateway, which is built around a central, modularly extensible server that can run on any PC or home gateway. It manages two sets of modules: one set offering the actual services and another set handling the IP-based wireless interaction with the client applications on the mobile devices. These modules can be added and removed dynamically, offering new services on the fly. Currently services for storage, printing, domotics and playing music are provided. Others can easily be added later on. This paper discusses the architecture and development, the management of modules, the actual services and their benefits. Besides a proprietary implementation, it also looks into OSGi and how both platforms compare to each other, concerning design, architecture, ease of development, functionality, ...

Quasi-Dirac neutrino oscillations

NASA Astrophysics Data System (ADS)

Anamiati, Gaetana; Fonseca, Renato M.; Hirsch, Martin

2018-05-01

Dirac neutrino masses require two distinct neutral Weyl spinors per generation, with a special arrangement of masses and interactions with charged leptons. Once this arrangement is perturbed, lepton number is no longer conserved and neutrinos become Majorana particles. If these lepton number violating perturbations are small compared to the Dirac mass terms, neutrinos are quasi-Dirac particles. Alternatively, this scenario can be characterized by the existence of pairs of neutrinos with almost degenerate masses, and a lepton mixing matrix which has 12 angles and 12 phases. In this work we discuss the phenomenology of quasi-Dirac neutrino oscillations and derive limits on the relevant parameter space from various experiments. In one parameter perturbations of the Dirac limit, very stringent bounds can be derived on the mass splittings between the almost degenerate pairs of neutrinos. However, we also demonstrate that with suitable changes to the lepton mixing matrix, limits on such mass splittings are much weaker, or even completely absent. Finally, we consider the possibility that the mass splittings are too small to be measured and discuss bounds on the new, nonstandard lepton mixing angles from current experiments for this case.

The SWAN biomedical discourse ontology.

PubMed

Ciccarese, Paolo; Wu, Elizabeth; Wong, Gwen; Ocana, Marco; Kinoshita, June; Ruttenberg, Alan; Clark, Tim

2008-10-01

Developing cures for highly complex diseases, such as neurodegenerative disorders, requires extensive interdisciplinary collaboration and exchange of biomedical information in context. Our ability to exchange such information across sub-specialties today is limited by the current scientific knowledge ecosystem's inability to properly contextualize and integrate data and discourse in machine-interpretable form. This inherently limits the productivity of research and the progress toward cures for devastating diseases such as Alzheimer's and Parkinson's. SWAN (Semantic Web Applications in Neuromedicine) is an interdisciplinary project to develop a practical, common, semantically structured, framework for biomedical discourse initially applied, but not limited, to significant problems in Alzheimer Disease (AD) research. The SWAN ontology has been developed in the context of building a series of applications for biomedical researchers, as well as in extensive discussions and collaborations with the larger bio-ontologies community. In this paper, we present and discuss the SWAN ontology of biomedical discourse. We ground its development theoretically, present its design approach, explain its main classes and their application, and show its relationship to other ongoing activities in biomedicine and bio-ontologies.

Current evidence and future directions for research with omega-3 fatty acids and attention deficit hyperactivity disorder.

PubMed

Gow, Rachel V; Hibbeln, Joseph R; Parletta, Natalie

2015-03-01

Nutritional insufficiencies of nutrients such as omega-3 highly unsaturated fatty acids (HUFAs), vitamins and minerals have been linked to suboptimal developmental outcomes including attention deficit hyperactivity disorder (ADHD). Although the predominant treatment is currently psychostimulant medications, randomized clinical trials with omega-3 HUFAs have reported small-to-modest effects in reducing symptoms of ADHD in children despite arguable individual methodological and design misgivings. This review presents, discusses and critically evaluates data and findings from meta-analytic and systematic reviews and clinical trials published within the last 12 months. Recent trajectories of this research are discussed, such as comparing eicosapentaenoic acid and docosahexaenoic acid and testing the efficacy of omega-3 HUFAs as an adjunct to methylphenidate. Discussion includes highlighting limitations and potential future directions such as addressing variable findings by accounting for other nutritional deficiencies and behavioural food intolerances. The authors conclude that given the current economic burden of ADHD, estimated in the region of $77 billion in the USA alone, in addition to the fact that a proportion of patients with ADHD are either treatment resistant, nonresponders or withdraw from medication because of adverse side-effects, the investigation of nonpharmacological interventions including omega-3 HUFAs in clinical practice warrants extrapolating.

High- and Low-Load Resistance Training: Interpretation and Practical Application of Current Research Findings.

PubMed

Fisher, James; Steele, James; Smith, Dave

2017-03-01

Our current state of knowledge regarding the load (lighter or heavier) lifted in resistance training programmes that will result in 'optimal' strength and hypertrophic adaptations is unclear. Despite this, position stands and recommendations are made based on, we propose, limited evidence to lift heavier weights. Here we discuss the state of evidence on the impact of load and how it, as a single variable, stimulates adaptations to take place and whether evidence for recommending heavier loads is available, well-defined, currently correctly interpreted or has been overlooked. Areas of discussion include electromyography amplitude, in vivo and in vitro methods of measuring hypertrophy, and motor schema and skill acquisition. The present piece clarifies to trainers and trainees the impact of these variables by discussing interpretation of synchronous and sequential motor unit recruitment and revisiting the size principle, poor agreement between whole-muscle cross-sectional area (CSA) and biopsy-determined changes in myofibril CSA, and neural adaptations around task specificity. Our opinion is that the practical implications of being able to self-select external load include reducing the need for specific facility memberships, motivating older persons or those who might be less confident using heavy loads, and allowing people to undertake home- or field-based resistance training intervention strategies that might ultimately improve exercise adherence.

Micromanaging cardiac regeneration: Targeted delivery of microRNAs for cardiac repair and regeneration

PubMed Central

Kamps, Jan AAM; Krenning, Guido

2016-01-01

The loss of cardiomyocytes during injury and disease can result in heart failure and sudden death, while the adult heart has a limited capacity for endogenous regeneration and repair. Current stem cell-based regenerative medicine approaches modestly improve cardiomyocyte survival, but offer neglectable cardiomyogenesis. This has prompted the need for methodological developments that crease de novo cardiomyocytes. Current insights in cardiac development on the processes and regulatory mechanisms in embryonic cardiomyocyte differentiation provide a basis to therapeutically induce these pathways to generate new cardiomyocytes. Here, we discuss the current knowledge on embryonic cardiomyocyte differentiation and the implementation of this knowledge in state-of-the-art protocols to the direct reprogramming of cardiac fibroblasts into de novo cardiomyocytes in vitro and in vivo with an emphasis on microRNA-mediated reprogramming. Additionally, we discuss current advances on state-of-the-art targeted drug delivery systems that can be employed to deliver these microRNAs to the damaged cardiac tissue. Together, the advances in our understanding of cardiac development, recent advances in microRNA-based therapeutics, and innovative drug delivery systems, highlight exciting opportunities for effective therapies for myocardial infarction and heart failure. PMID:26981212

Imaging flow cytometry for phytoplankton analysis.

PubMed

Dashkova, Veronika; Malashenkov, Dmitry; Poulton, Nicole; Vorobjev, Ivan; Barteneva, Natasha S

2017-01-01

This review highlights the concepts and instrumentation of imaging flow cytometry technology and in particular its use for phytoplankton analysis. Imaging flow cytometry, a hybrid technology combining speed and statistical capabilities of flow cytometry with imaging features of microscopy, is rapidly advancing as a cell imaging platform that overcomes many of the limitations of current techniques and contributed significantly to the advancement of phytoplankton analysis in recent years. This review presents the various instrumentation relevant to the field and currently used for assessment of complex phytoplankton communities' composition and abundance, size structure determination, biovolume estimation, detection of harmful algal bloom species, evaluation of viability and metabolic activity and other applications. Also we present our data on viability and metabolic assessment of Aphanizomenon sp. cyanobacteria using Imagestream X Mark II imaging cytometer. Herein, we highlight the immense potential of imaging flow cytometry for microalgal research, but also discuss limitations and future developments. Copyright © 2016 Elsevier Inc. All rights reserved.

Stem Cells for Cardiac Regeneration by Cell Therapy and Myocardial Tissue Engineering

NASA Astrophysics Data System (ADS)

Wu, Jun; Zeng, Faquan; Weisel, Richard D.; Li, Ren-Ke

Congestive heart failure, which often occurs progressively following a myocardial infarction, is characterized by impaired myocardial perfusion, ventricular dilatation, and cardiac dysfunction. Novel treatments are required to reverse these effects - especially in older patients whose endogenous regenerative responses to currently available therapies are limited by age. This review explores the current state of research for two related approaches to cardiac regeneration: cell therapy and tissue engineering. First, to evaluate cell therapy, we review the effectiveness of various cell types for their ability to limit ventricular dilatation and promote functional recovery following implantation into a damaged heart. Next, to assess tissue engineering, we discuss the characteristics of several biomaterials for their potential to physically support the infarcted myocardium and promote implanted cell survival following cardiac injury. Finally, looking ahead, we present recent findings suggesting that hybrid constructs combining a biomaterial with stem and supporting cells may be the most effective approaches to cardiac regeneration.

Endoscopic submucosal dissection in the West: Current status and future directions.

PubMed

Ma, Michael X; Bourke, Michael J

2018-05-01

Endoscopic submucosal dissection (ESD) was first conceptually described almost 30 years ago in Japan and is now widely practiced throughout East Asia. ESD expands the boundaries of endoscopic resection (ER) by allowing en bloc resection of large early neoplastic lesions within the gastrointestinal tract (GIT). This offers advantages over other ER techniques by facilitating definitive histological staging and curative treatment of early cancer in selected cases. Indeed, the experience of ESD in Eastern countries is significant, and excellent outcomes from high-volume centers are reported. The potential benefits of ESD are recognized by Western endoscopists, but its adoption has been limited. A number of factors contribute to this, including epidemiological differences in GIT neoplasia between Western and Eastern populations and limitations in training opportunities. In this review, we discuss the role of ESD, its current status and the future in Western endoscopic practice. © 2017 Japan Gastroenterological Endoscopy Society.

Analysis of a flux-coupling type superconductor fault current limiter with pancake coils

NASA Astrophysics Data System (ADS)

Liu, Shizhuo; Xia, Dong; Zhang, Zhifeng; Qiu, Qingquan; Zhang, Guomin

2017-10-01

The characteristics of a flux-coupling type superconductor fault current limiter (SFCL) with pancake coils are investigated in this paper. The conventional double-wound non-inductive pancake coil used in AC power systems has an inevitable defect in Voltage Sourced Converter Based High Voltage DC (VSC-HVDC) power systems. Due to its special structure, flashover would occur easily during the fault in high voltage environment. Considering the shortcomings of conventional resistive SFCLs with non-inductive coils, a novel flux-coupling type SFCL with pancake coils is carried out. The module connections of pancake coils are performed. The electromagnetic field and force analysis of the module are contrasted under different parameters. To ensure proper operation of the module, the impedance of the module under representative operating conditions is calculated. Finally, the feasibility of the flux-coupling type SFCL in VSC-HVDC power systems is discussed.

Web survey of sleep problems associated with early-onset bipolar spectrum disorders.

PubMed

Lofthouse, Nicholas; Fristad, Mary; Splaingard, Mark; Kelleher, Kelly; Hayes, John; Resko, Susan

2008-05-01

As research on sleep difficulties associated with Early-Onset Bipolar Spectrum Disorders (EBSD) is limited, a web-based survey was developed to further explore these problems. 494 parents of 4-to-12 year-olds, identified by parents as being diagnosed with EBSD, completed a web survey about past and current EBSD-related sleep problems. The survey included Children's Sleep Habits Questionnaire (CSHQ) items and sleep problems from the International Classification of Sleep Disorders 2nd edition. Nearly all parents reported some type of past or current EBSD-sleep problem. Most occurred during a worst mood period, particularly with mixed manic-depressive symptoms. Symptoms caused impairments at home, school, or with peers in 96.9% of the sample and across all three contexts in 64.0% of children. Sleep problems were also noted after three-day weekends and Spring and Fall Daylight Savings time changes. Findings, study limitations, and implications for treatment and etiology are discussed.

Current trends and future prospects of biotechnological interventions through tissue culture in apple.

PubMed

Bhatti, Shammi; Jha, Gopaljee

2010-11-01

Apple (Malus domestica Borkh.), which is a widely cultivated, important economic fruit crop with nutritive and medicinal importance, has emerged as a model horticultural crop in this post-genomic era. Apple cultivation is heavily dependent on climatic condition and is susceptible to several diseases caused by fungi, bacteria, viruses, insects, etc. Extensive research work has been carried out to standardize tissue culture protocols and utilize them in apple improvement. We review the in vitro shoot multiplication, rooting, transformation and regeneration methodologies in apple and tabulate various such protocols for easy reference. The utility and limitation of transgenesis in apple improvement have also been summarized. The concepts of marker-free plants, use of non-antibiotic resistance selectable markers, and cisgenic and intragenic approaches are highlighted. Furthermore, the limitations, current trends and future prospects of tissue culture-mediated biotechnological interventions in apple improvement are discussed.

A critical appraisal of lubiprostone in the treatment of chronic constipation in the elderly.

PubMed

Gras-Miralles, Beatriz; Cremonini, Filippo

2013-01-01

Chronic constipation is a common disorder in the general population, with higher prevalence in the elderly, and is associated with worse quality of life and with greater health care utilization. Lubiprostone is an intestinal type-2 chloride channel activator that increases intestinal fluid secretion, small intestinal transit, and stool passage. Lubiprostone is currently approved by the US Food and Drug Administration for the treatment of chronic idiopathic constipation and of irritable bowel syndrome with predominant constipation. This review outlines current approaches and limitations in the treatment of chronic constipation in the elderly and discusses the results, limitations, and applicability of randomized, controlled trials of lubiprostone that have been conducted in the general and elderly population, with additional focus on the use of lubiprostone in constipation in Parkinson's disease and in opioid-induced constipation, two clinical entities that can be comorbid in elderly patients.

Food for Thought …

PubMed Central

Smirnova, Lena; Hogberg, Helena T.; Leist, Marcel; Hartung, Thomas

2016-01-01

Summary In recent years neurodevelopmental problems in children have increased at a rate that suggests lifestyle factors and chemical exposures as likely contributors. When environmental chemicals contribute to neurodevelopmental disorders developmental neurotoxicity (DNT) becomes an enormous concern. But how can it be tackled? Current animal test-based guidelines are prohibitively expensive, at $1.4 million per substance, while their predictivity for human health effects may be limited, and mechanistic data that would help species extrapolation are not available. A broader screening for substances of concern requires a reliable testing strategy, applicable to larger numbers of substances, and sufficiently predictive to warrant further testing. This review discusses the evidence for possible contributions of environmental chemicals to DNT, limitations of the current test paradigm, emerging concepts and technologies pertinent to in vitro DNT testing and assay evaluation, as well as the prospect of a paradigm shift based on 21st century technologies. PMID:24687333

Graphene-based photovoltaic cells for near-field thermal energy conversion

PubMed Central

Messina, Riccardo; Ben-Abdallah, Philippe

2013-01-01

Thermophotovoltaic devices are energy-conversion systems generating an electric current from the thermal photons radiated by a hot body. While their efficiency is limited in far field by the Schockley-Queisser limit, in near field the heat flux transferred to a photovoltaic cell can be largely enhanced because of the contribution of evanescent photons, in particular for a source supporting a surface mode. Unfortunately, in the infrared where these systems operate, the mismatch between the surface-mode frequency and the semiconductor gap reduces drastically the potential of this technology. In this paper we propose a modified thermophotovoltaic device in which the cell is covered by a graphene sheet. By discussing the transmission coefficient and the spectral properties of the flux, we show that both the cell efficiency and the produced current can be enhanced, paving the way to promising developments for the production of electricity from waste heat. PMID:23474891

Intraoperative optical coherence tomography of the cerebral cortex using a 7 degree-of freedom robotic arm

NASA Astrophysics Data System (ADS)

Reyes Perez, Robnier; Jivraj, Jamil; Yang, Victor X. D.

2017-02-01

Optical Coherence Tomography (OCT) provides a high-resolution imaging technique with limited depth penetration. The current use of OCT is limited to relatively small areas of tissue for anatomical structure diagnosis or minimally invasive guided surgery. In this study, we propose to image a large area of the surface of the cerebral cortex. This experiment aims to evaluate the potential difficulties encountered when applying OCT imaging to large and irregular surface areas. The current state-of-the-art OCT imaging technology uses scanning systems with at most 3 degrees-of-freedom (DOF) to obtain a 3D image representation of the sample tissue. We propose the use of a 7 DOF industrial robotic arm to increase the scanning capabilities of our OCT. Such system will be capable of acquiring data from large samples of tissue that are too irregular for conventional methods. Advantages and disadvantages of our system are discussed.

Photovoltaic array: Power conditioner interface characteristics

NASA Technical Reports Server (NTRS)

Gonzalez, C. C.; Hill, G. M.; Ross, R. G., Jr.

1982-01-01

The electrical output (power, current, and voltage) of flat plate solar arrays changes constantly, due primarily to changes in cell temperature and irradiance level. As a result, array loads such as dc-to-ac power conditioners must be capable of accommodating widely varying input levels while maintaining operation at or near the maximum power point of the array. The array operating characteristics and extreme output limits necessary for the systematic design of array load interfaces under a wide variety of climatic conditions are studied. A number of interface parameters are examined, including optimum operating voltage, voltage energy, maximum power and current limits, and maximum open circuit voltage. The effect of array degradation and I-V curve fill factor or the array power conditioner interface is also discussed. Results are presented as normalized ratios of power conditioner parameters to array parameters, making the results universally applicable to a wide variety of system sizes, sites, and operating modes.

Graphene-based photovoltaic cells for near-field thermal energy conversion.

PubMed

Messina, Riccardo; Ben-Abdallah, Philippe

2013-01-01

Thermophotovoltaic devices are energy-conversion systems generating an electric current from the thermal photons radiated by a hot body. While their efficiency is limited in far field by the Schockley-Queisser limit, in near field the heat flux transferred to a photovoltaic cell can be largely enhanced because of the contribution of evanescent photons, in particular for a source supporting a surface mode. Unfortunately, in the infrared where these systems operate, the mismatch between the surface-mode frequency and the semiconductor gap reduces drastically the potential of this technology. In this paper we propose a modified thermophotovoltaic device in which the cell is covered by a graphene sheet. By discussing the transmission coefficient and the spectral properties of the flux, we show that both the cell efficiency and the produced current can be enhanced, paving the way to promising developments for the production of electricity from waste heat.

A critical appraisal of lubiprostone in the treatment of chronic constipation in the elderly

PubMed Central

Gras-Miralles, Beatriz; Cremonini, Filippo

2013-01-01

Chronic constipation is a common disorder in the general population, with higher prevalence in the elderly, and is associated with worse quality of life and with greater health care utilization. Lubiprostone is an intestinal type-2 chloride channel activator that increases intestinal fluid secretion, small intestinal transit, and stool passage. Lubiprostone is currently approved by the US Food and Drug Administration for the treatment of chronic idiopathic constipation and of irritable bowel syndrome with predominant constipation. This review outlines current approaches and limitations in the treatment of chronic constipation in the elderly and discusses the results, limitations, and applicability of randomized, controlled trials of lubiprostone that have been conducted in the general and elderly population, with additional focus on the use of lubiprostone in constipation in Parkinson’s disease and in opioid-induced constipation, two clinical entities that can be comorbid in elderly patients. PMID:23439964

Vorticity equation for MHD fast waves in geospace environment

NASA Technical Reports Server (NTRS)

Yamauchi, M.; Lundin, R.; Lui, A. T. Y.

1993-01-01

The MHD vorticity equation is modified in order to apply it to nonlinear MHD fast waves or shocks when their extent along the magnetic field is limited. Field-aligned current (FAC) generation is also discussed on the basis of this modified vorticity equation. When the wave normal is not aligned to the finite velocity convection and the source region is spatially limited, a longitudinal polarization causes a pair of plus and minus charges inside the compressional plane waves or shocks, generating a pair of FACs. This polarization is not related to the separation between the electrons and ions caused by their difference in mass, a separation which is inherent to compressional waves. The resultant double field-aligned current structure exists both with and without the contributions from curvature drift, which is questionable in terms of its contribution to vorticity change from the viewpoint of single-particle motion.

Environmentally-induced voltage limitations in large space power systems

NASA Technical Reports Server (NTRS)

Stevens, N. J.

1984-01-01

Large power systems proposed for future space missions imply higher operating voltage requirements which, in turn, will interact with the space plasma environment. The effects of these interactions can only be inferred because of the limited data base of ground simulations, small test samples, and two space flight experiments. This report evaluates floating potentials for a 100 kW power system operating at 300, 500, 750, and 1000 volts in relation to this data base. Of primary concern is the possibility of discharging to space. The implications of such discharges were studied at the 500 volt operational setting. It was found that discharging can shut down the power system if the discharge current exceeds the array short circuit current. Otherwise, a power oscillation can result that ranges from 2 to 20 percent, depending upon the solar array area involved in the discharge. Means of reducing the effect are discussed.

Noninvasive Brain Stimulation in Pediatric ADHD: A Review

PubMed Central

Rubio, Belen; Boes, Aaron D.; Laganiere, Simon; Rotenberg, Alexander; Jeurissen, Danique; Pascual-Leone, Alvaro

2015-01-01

Attention-deficit hyperactivity disorder (ADHD) is one of the most prevalent neurodevelopmental disorders in the pediatric population. The clinical management of ADHD is currently limited by a lack of reliable diagnostic biomarkers and inadequate therapy for a minority of patients that do not respond to standard pharmacotherapy. There is optimism that noninvasive brain stimulation may help to address these limitations. Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are two methods of noninvasive brain stimulation that modulate cortical excitability and brain network activity. TMS can be used diagnostically to probe cortical neurophysiology, while daily use of repetitive TMS or tDCS can induce long-lasting and potentially therapeutic changes in targeted networks. In this review we highlight research showing the potential diagnostic and therapeutic applications of TMS and tDCS in pediatric ADHD. We also discuss the safety and ethics of using these tools in the pediatric population. PMID:26661481

Sustainable development: a regional perspective.

PubMed

Icamina, P

1988-12-01

This article discusses sustainable development in Asia and current environmental problems in this region. Droughts and rainy seasons pose a major concern indicating environmental limitations: India's 1987 drought halted world grain production and China suffered US $435 million in flooding damage. Deforestation and land degradation are consequences of a rising population's demand for agriculture, fuelwood, irrigation, and hydroelectric projects; 1815 million hectares of forest are cleared/year and 40% of the land could possible be subjected to soil erosion. Although population growth is declining in some Asian countries, the continent inhabits the greatest proportion of world population; 300 million are underfed. Food production remains a problem for this region because of bad weather, highly populated areas, less cropland, soil erosion, and limited water supply. Efforts currently employed to conserve natural resources include community reforestation, providing available drinking water, substituting firewood for fuelwood, and delivering primary health care.

Exploring the value of technology to stimulate interprofessional discussion and education: a needs assessment of emergency medicine professionals.

PubMed

Riley, Jennifer; McGowan, Melissa; Rozmovits, Linda

2014-06-30

The emergency department (ED) is an environment fraught with increasing patient volumes, competing priorities, fluctuating information, and ad hoc interprofessional clinical teams. Limited time is available to reflect on and discuss clinical experiences, policies, or research with others on the involved team. Online resources, such as webcasts and blogs, offer an accessible platform for emergency shift workers to engage in interprofessional discussion and education. Our objective was to explore the current opportunities for shared learning and discussion and to discover the potential of online resources to foster and facilitate interprofessional education within an academic tertiary emergency department community. A qualitative study using semistructured interviews was conducted to solicit participants' views of the current culture of IPE in the ED, the potential value of introducing new online resources and technology in support of IPE, and possible barriers to uptake. Participation was voluntary and participants provided verbal informed consent. Online resources discussed included webcasts, interactive discussion forums, websites, and dashboard with links to central repositories. Identified barriers to uptake of new online resources were an unwillingness to "work" off-shift, a dislike of static one-directional communication, concerns with confidentiality, and the suggestion that new resources would be used by only a select few. Owing to the sensitive dynamics of emergency medicine-and the preference among its professional staff to foster interprofessional discussion and education through personal engagement, in an unhurried, non-stressful environment-introducing and investing in online resources should be undertaken with caution.

Current and future resources for functional metagenomics

PubMed Central

Lam, Kathy N.; Cheng, Jiujun; Engel, Katja; Neufeld, Josh D.; Charles, Trevor C.

2015-01-01

Functional metagenomics is a powerful experimental approach for studying gene function, starting from the extracted DNA of mixed microbial populations. A functional approach relies on the construction and screening of metagenomic libraries—physical libraries that contain DNA cloned from environmental metagenomes. The information obtained from functional metagenomics can help in future annotations of gene function and serve as a complement to sequence-based metagenomics. In this Perspective, we begin by summarizing the technical challenges of constructing metagenomic libraries and emphasize their value as resources. We then discuss libraries constructed using the popular cloning vector, pCC1FOS, and highlight the strengths and shortcomings of this system, alongside possible strategies to maximize existing pCC1FOS-based libraries by screening in diverse hosts. Finally, we discuss the known bias of libraries constructed from human gut and marine water samples, present results that suggest bias may also occur for soil libraries, and consider factors that bias metagenomic libraries in general. We anticipate that discussion of current resources and limitations will advance tools and technologies for functional metagenomics research. PMID:26579102

Current and future resources for functional metagenomics.

PubMed

Lam, Kathy N; Cheng, Jiujun; Engel, Katja; Neufeld, Josh D; Charles, Trevor C

2015-01-01

Functional metagenomics is a powerful experimental approach for studying gene function, starting from the extracted DNA of mixed microbial populations. A functional approach relies on the construction and screening of metagenomic libraries-physical libraries that contain DNA cloned from environmental metagenomes. The information obtained from functional metagenomics can help in future annotations of gene function and serve as a complement to sequence-based metagenomics. In this Perspective, we begin by summarizing the technical challenges of constructing metagenomic libraries and emphasize their value as resources. We then discuss libraries constructed using the popular cloning vector, pCC1FOS, and highlight the strengths and shortcomings of this system, alongside possible strategies to maximize existing pCC1FOS-based libraries by screening in diverse hosts. Finally, we discuss the known bias of libraries constructed from human gut and marine water samples, present results that suggest bias may also occur for soil libraries, and consider factors that bias metagenomic libraries in general. We anticipate that discussion of current resources and limitations will advance tools and technologies for functional metagenomics research.

A Framework to Understand Extreme Space Weather Event Probability.

PubMed

Jonas, Seth; Fronczyk, Kassandra; Pratt, Lucas M

2018-03-12

An extreme space weather event has the potential to disrupt or damage infrastructure systems and technologies that many societies rely on for economic and social well-being. Space weather events occur regularly, but extreme events are less frequent, with a small number of historical examples over the last 160 years. During the past decade, published works have (1) examined the physical characteristics of the extreme historical events and (2) discussed the probability or return rate of select extreme geomagnetic disturbances, including the 1859 Carrington event. Here we present initial findings on a unified framework approach to visualize space weather event probability, using a Bayesian model average, in the context of historical extreme events. We present disturbance storm time (Dst) probability (a proxy for geomagnetic disturbance intensity) across multiple return periods and discuss parameters of interest to policymakers and planners in the context of past extreme space weather events. We discuss the current state of these analyses, their utility to policymakers and planners, the current limitations when compared to other hazards, and several gaps that need to be filled to enhance space weather risk assessments. © 2018 Society for Risk Analysis.

Extending SIESTA capabilities: removing field-periodic and stellarator symmetric limitations

NASA Astrophysics Data System (ADS)

Cook, C. R.; Hirshman, S. P.; Sanchez, R.; Anderson, D. T.

2011-10-01

SIESTA is a three-dimensional magnetohydrodynamics equilibrium code capable of resolving magnetic islands in toroidal plasma confinement devices. Currently SIESTA assumes that plasma perturbations, and thus also magnetic islands, are field-periodic. This limitation is being removed from the code by allowing the displacement toroidal mode number to not be restricted to multiples of the number of field periods. Extending SIESTA in this manner will allow larger, lower-order resonant islands to form in devices such as CTH. An example of a non-field-periodic perturbation in CTH will be demonstrated. Currently the code also operates in a stellarator-symmetric fashion in which an ``up-down'' symmetry is present at some toroidal angle. Nearly all of the current tokamaks (and ITER in the future) operate with a divertor and as such do not possess stellarator symmetry. Removal of this symmetry restriction requires including both sine and cosine terms in the Fourier expansion for the geometry of the device and the fields contained within. The current status of this extension of the code will be discussed, along with the method of implementation. U.S. DOE Contract No. DE-AC05-00OR22725 with UT-Battelle, LLC.

Maxwell's theory of eddy currents in thin conducting sheets, and applications to electromagnetic shielding and MAGLEV

NASA Astrophysics Data System (ADS)

Saslow, W. M.

1992-08-01

Using the example of a monopole that is spontaneously generated above a thin conducting sheet, the simplicity and power of Maxwell's 1872 theory of eddy currents in thin conducting sheets is illustrated. This theory employs a receding image construction, with a characteristic recession velocity v0=2/(μ0σd), where the sheet has conductivity σ and thickness d. A modern derivation of the theory, employing the magnetic scalar potential, is also presented, with explicit use of the uniqueness theorem. Also discussed are limitations on the theory of which Maxwell, living in a time before the discovery of the electron, could not have been aware. Previous derivations either have not appealed explicitly to the uniqueness theorem, or have employed the now unfamiliar current function, and are therefore either incomplete or inaccessible to the modern reader. After the derivation, two important examples considered by Maxwell are presented-a monopole moving above a thin conducting sheet, and a monopole above a rotating thin conducting sheet (Arago's disk)-and it is argued that the lift force thus obtained makes Maxwell the grandfather, if not the father, of eddy current MAGLEV transportation systems. An energy conservation argument is given to derive Davis's result that, for a magnet of arbitrary size and shape moving parallel to a thin conducting sheet at a characteristic height h, with velocity v, the ratio of drag force to lift force is equal to v0/v, provided that d≪δc, where δc =√2h/(μ0σv). If d≫δc, the eddy currents are confined to a thickness δc, leading to an increase in the dissipation and the drag by a factor of d/δc, so that the ratio of drag to lift force becomes proportional to √v'0/v, where v'0 = 2/(μ0σh). The case of a monopole fixed in position, but oscillating in strength (such as can be simulated by one end of a long, narrow, ac solenoid), is also treated. This is employed to obtain the results for an oscillating magnetic dipole whose moment is normal to the sheet. A general discussion of electromagnetic induction and electrical conductors, both thick and thin, is given, emphasizing the difference between the high-frequency limit, where flux expulsion occurs and the self-inductance dominates, and the low-frequency limit, where the flux penetrates and the electrical resistance dominates. A discussion of Lenz's law, as a statement about motion, is given. It is argued that the most general form of such a statement of Lenz's law is that induced currents tend to accelerate a conductor in the direction that most effectively decreases the rate of Joule heating. A calculation, in the low-frequency limit, of the drag force on a magnetic dipole falling down a long conducting tube, is also given. This last case can be given a striking demonstration with the newly available neodymium-iron-boron magnets.

Environmental Barrier Coatings for Ceramics and Ceramic Composites

NASA Technical Reports Server (NTRS)

Lee, Kang N.; Fox, Dennis; Eldridge, Jeffrey; Robinson, R. Craig; Bansal, Narottam

2004-01-01

One key factor that limits the performance of current gas turbine engines is the temperature capability of hot section structural components. Silicon-based ceramics, such as SiC/SiC composites and monolithic Si3N4, are leading candidates to replace superalloy hot section components in the next generation gas turbine engines due to their excellent high temperature properties. A major stumbling block to realizing Si-based ceramic hot section components is the recession of Si-based ceramics in combustion environments due to the volatilization of silica scale by water vapor. An external environmental barrier coating (EBC) is the most promising approach to preventing the recession. Current EBCs are based on silicon, mullite (3A12O3-2SiO2) and BSAS (barium strontium aluminum silicate with celsian structure). Volatility of BSAS, BSAS-silica chemical reaction, and low melting point of silicon limit the durability and temperature capability of current EBCs. Research is underway to develop EBCs with longer life and enhanced temperature capability. Understanding key issues affecting the performance of current EBCs is necessary for successful development of advanced EBCs. These issues include stress, chemical compatibility, adherence, and water vapor stability. Factors that affect stress are thermal expansion mismatch, phase stability, chemical stability, elastic modulus, etc. The current understanding on these issues will be discussed.

Contemporary Science and Worldview-Making

NASA Astrophysics Data System (ADS)

Cordero, Alberto

2009-06-01

This paper discusses the impact of contemporary scientific knowledge on worldviews. The first three sections provide epistemological background for the arguments that follow. Sections 2 and 3 discuss the reliable part of science, specifically the characterization, scope and limits of the present scientific canon. Section 4 deals with the mode of thinking responsible for both the canon’s credibility and its power to guide speculative activity. With these preliminaries in place, the remainder of the paper addresses the issue of tolerance to “alternative perspectives”. The analyses in this part focus on the extent to which mature scientific thought embodies open-mindedness, with pluralism and competition between perspectives as central themes. I argue for four related claims, concerning scientific literacy, the impact of the canon on rational speculation, the limits of scientific pluralism, and the popular idea that recent forms of “scientific (natural) theology” have rational merit and can help worldview-making in our age, respectively: (C1) Which theories and narratives (or parts of them) belong in the scientific canon, and whether they are worldview independent, are matters contingent upon the state of knowledge—not something one can convincingly determine on metascientific or transcendental insight. (C2) The current scientific canon and its associated methodology provide research with strong directionality, often against popular currents. (C3) Current science does marginalize some views dear to many people. (C4) Although natural theology “officially” purports to embody scientific methodology, all it presently has on offer are poorly thought out ventures embodying (at best) only relaxed versions of that methodology; if so, the relationship between current projects in natural theology and science cannot (without begging the question) be reasonably described as one of “partial overlap”, “mutual modification”, or “ongoing complementarity”.

Predicted aircraft effects on stratospheric ozone

NASA Technical Reports Server (NTRS)

Ko, Malcolm K. W.; Wofsy, Steve; Kley, Dieter; Zhadin, Evgeny A.; Johnson, Colin; Weisenstein, Debra; Prather, Michael J.; Wuebbles, Donald J.

1991-01-01

The possibility that the current fleet of subsonic aircraft may already have caused detectable changes in both the troposphere and stratosphere has raised concerns about the impact of such operations on stratospheric ozone and climate. Recent interest in the operation of supersonic aircraft in the lower stratosphere has heightened such concerns. Previous assessments of impacts from proposed supersonic aircraft were based mostly on one-dimensional model results although a limited number of multidimensional models were used. In the past 15 years, our understanding of the processes that control the atmospheric concentrations of trace gases has changed dramatically. This better understanding was achieved through accumulation of kinetic data and field observations as well as development of new models. It would be beneficial to start examining the impact of subsonic aircraft to identify opportunities to study and validate the mechanisms that were proposed to explain the ozone responses. The two major concerns are the potential for a decrease in the column abundance of ozone leading to an increase in ultraviolet radiation at the ground, and redistribution of ozone in the lower stratosphere and upper troposphere leading to changes in the Earth's climate. Two-dimensional models were used extensively for ozone assessment studies, with a focus on responses to chlorine perturbations. There are problems specific to the aircraft issues that are not adequately addressed by the current models. This chapter reviews the current status of the research on aircraft impact on ozone with emphasis on immediate model improvements necessary for extending our understanding. The discussion will be limited to current and projected commercial aircraft that are equipped with air-breathing engines using conventional jet fuel. The impacts are discussed in terms of the anticipated fuel use at cruise altitude.

Pharmacological therapy of Parkinson's disease: current options and new avenues.

PubMed

Simola, Nicola; Pinna, Annalisa; Fenu, Sandro

2010-11-01

Parkinson's disease is a neurodegenerative pathology which affects the dopaminergic neurons in the mesencephalon, leading to a progressive and relentless motor disability and to non-motor symptoms of different severity. The aim of this review is to summarize the features of drugs currently used in the pharmacotherapy of Parkinson's disease, with a look at their beneficial effects and limitations. Drugs acting on dopamine transmission, as L-DOPA, direct dopaminergic agonists, inhibitors for either the MAO or COMT enzymes and drugs acting on neurotransmitters other than dopamine (e.g. acetylcholine, glutamate) will be covered. Investigational drugs currently under examination for their therapeutic potential in Parkinson's disease and recent patents which may be relevant to the field will be also discussed.

Surface Passivation of CdZnTe Detector by Hydrogen Peroxide Solution Etching

NASA Technical Reports Server (NTRS)

Hayes, M.; Chen, H.; Chattopadhyay, K.; Burger, A.; James, R. B.

1998-01-01

The spectral resolution of room temperature nuclear radiation detectors such as CdZnTe is usually limited by the presence of conducting surface species that increase the surface leakage current. Studies have shown that the leakage current can be reduced by proper surface preparation. In this study, we try to optimize the performance of CdZnTe detector by etching the detector with hydrogen peroxide solution as function of concentration and etching time. The passivation effect that hydrogen peroxide introduces have been investigated by current-voltage (I-V) measurement on both parallel strips and metal-semiconductor-metal configurations. The improvements on the spectral response of Fe-55 and 241Am due to hydrogen peroxide treatment are presented and discussed.

Glycated albumin: from biochemistry and laboratory medicine to clinical practice.

PubMed

Dozio, Elena; Di Gaetano, Nicola; Findeisen, Peter; Corsi Romanelli, Massimiliano Marco

2017-03-01

This review summarizes current knowledge about glycated albumin. We review the changes induced by glycation on the properties of albumin, the pathological implications of high glycated albumin levels, glycated albumin quantification methods, and the use of glycated albumin as a complementary biomarker for diabetes mellitus diagnosis and monitoring and for dealing with long-term complications. The advantages and limits of this biomarker in different clinical settings are also discussed.

Biohydrogen from Microalgae

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

Dubini, Alexandra; Gonzalez-Ballester, David

2016-03-01

This chapter provides an overview of the current state of knowledge of the mechanisms involved in biohydrogen production from microalgae. The known limitations linked to photohydrogen productivity are addressed. Particular attention is given to physiological and molecular strategies to sustain and improve hydrogen production. The impact of different nutrient stresses and the effect of carbon supply on hydrogen production are discussed. The genetic and metabolic engineering approaches for increasing hydrogen production are outlined.

Battery Cell Voltage Sensing and Balancing Using Addressable Transformers

NASA Technical Reports Server (NTRS)

Davies, Francis

2009-01-01

A document discusses the use of saturating transformers in a matrix arrangement to address individual cells in a high voltage battery. This arrangement is able to monitor and charge individual cells while limiting the complexity of circuitry in the battery. The arrangement has inherent galvanic isolation, low cell leakage currents, and allows a single bad cell in a battery of several hundred cells to be easily spotted.

Robotic liver surgery

PubMed Central

Leung, Universe

2014-01-01

Robotic surgery is an evolving technology that has been successfully applied to a number of surgical specialties, but its use in liver surgery has so far been limited. In this review article we discuss the challenges of minimally invasive liver surgery, the pros and cons of robotics, the evolution of medical robots, and the potentials in applying this technology to liver surgery. The current data in the literature are also presented. PMID:25392840

fMRI in the public eye

PubMed Central

Racine, Eric; Bar-Ilan, Ofek; Illes, Judy

2006-01-01

The wide dissemination and expanding applications of functional MRI have not escaped the attention of the media or discussion in the wider public arena. From the bench to the bedside, this technology has introduced substantial ethical challenges. Are the boundaries of what it can and cannot achieve being communicated to the public? Are its limitations understood? And given the complexities that are inherent to neuroscience, are current avenues for communication adequate? PMID:15685221

Phototriggerable Liposomes: Current Research and Future Perspectives

PubMed Central

Puri, Anu

2013-01-01

The field of cancer nanomedicine is considered a promising area for improved delivery of bioactive molecules including drugs, pharmaceutical agents and nucleic acids. Among these, drug delivery technology has made discernible progress in recent years and the areas that warrant further focus and consideration towards technological developments have also been recognized. Development of viable methods for on-demand spatial and temporal release of entrapped drugs from the nanocarriers is an arena that is likely to enhance the clinical suitability of drug-loaded nanocarriers. One such approach, which utilizes light as the external stimulus to disrupt and/or destabilize drug-loaded nanoparticles, will be the discussion platform of this article. Although several phototriggerable nanocarriers are currently under development, I will limit this review to the phototriggerable liposomes that have demonstrated promise in the cell culture systems at least (but not the last). The topics covered in this review include (i) a brief summary of various phototriggerable nanocarriers; (ii) an overview of the application of liposomes to deliver payload of photosensitizers and associated technologies; (iii) the design considerations of photoactivable lipid molecules and the chemical considerations and mechanisms of phototriggering of liposomal lipids; (iv) limitations and future directions for in vivo, clinically viable triggered drug delivery approaches and potential novel photoactivation strategies will be discussed. PMID:24662363

[Priority setting and bedside rationing: a discussion of empirical findings].

PubMed

Strech, Daniel

2011-01-01

In addition to empirical forecasts on the extent of the current and future limitations on health care resources, empirical data on the status quo of bedside rationing play a significant role in developing suitable alternatives in dealing with limited financial resources. This article presents and discusses selected results of the international and German survey research on bedside rationing. Survey studies among physicians could prove world-wide that rationing decisions are made already today by individual physicians in the in- and out-patient services. In German hospitals, rationing is also a wide-spread though non-transparent and not (yet) very common phenomenon for an individual physician. Varying criteria for bedside rationing contribute to the fact that the current approach to bedside rationing leads to dissatisfaction on the part of physicians and to a potential disadvantage of certain patient groups. Explicit, i.e. transparent and systematic, ways of rationing could remedy these deficiencies and are therefore clearly preferable in this context. However, further specification of the methods of explicit rationing and a critical evaluation of their application in practice are needed. Moreover, it is mainly the quality of the underlying evidence that determines whether or not the actual decisions become more reasonable and fair by means of more explicit rationing approaches. Copyright © 2011 S. Karger AG, Basel.

Making High Accuracy Null Depth Measurements for the LBTI Exozodi Survey

NASA Technical Reports Server (NTRS)

Mennesson, Bertrand; Defrere, Denis; Nowak, Matthias; Hinz, Philip; Millan-Gabet, Rafael; Absil, Oliver; Bailey, Vanessa; Bryden, Geoffrey; Danchi, William C.; Kennedy, Grant M.;

Making High Accuracy Null Depth Measurements for the LBTI ExoZodi Survey

NASA Technical Reports Server (NTRS)

Mennesson, Bertrand; Defrere, Denis; Nowak, Matthew; Hinz, Philip; Millan-Gabet, Rafael; Absil, Olivier; Bailey, Vanessa; Bryden, Geoffrey; Danchi, William; Kennedy, Grant M.;

Nanomedicines in gastroenterology and hepatology.

PubMed

Lamprecht, Alf

2015-04-01

Nanoscale systems are currently under investigation for multiple different diagnostic and therapeutic applications. These systems can be used to identify pathologically changed tissues or to selectively deliver drugs to these sites; both applications have an extremely high potential to ameliorate therapeutic outcomes for patients. Tissues as well as single cells can be targeted because of the small size of these systems, which enables enhanced diagnosis and increased specificity of therapy. Drug loads can be delivered directly to the site of action, which can result in a reduction in incidence and severity of adverse systemic effects. Several nano-based platform technologies are currently under investigation for use in therapeutic approaches, mainly for anti-inflammatory and anti-cancer therapies. Although many nanoscale systems show promising therapeutic outcomes in preclinical studies, only a limited number are ready for clinical use. This Review will discuss the diverse nanomaterials currently available and the first specific uses for select gastroenterological and hepatological pathologies. The discussion of diagnostic and therapeutic applications will consider realities of market introduction of these sometimes very complex systems in light of remaining regulatory challenges and hurdles for industrial production.

Institute on oil and gas law and taxation

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

Ernst, A.C.

1979-01-01

This volume contains discussions, by acknowledged authorities, of important legal and tax problems of the oil and gas industries. The articles were delivered in condensed form as lectures during the Thirtieth Annual Institute on Oil and Gas Law and Taxation held by the Southwest Legal Foundation. The following topics are discussed: crude oil issues; natural gas liquid-selected problems in regulation; recent developments in DOE audits of refiners and marketers; contrasting administrative procedures before the DOE, DOE organization - the limit of regulatory power, current major developments in federal natural gas legislation and regulation; dedication and abandonment - problems under sectionmore » 7(b) of the Natural Gas Act; Natural gas pipelines - their regulation and their current problems, current antitrust developments in oil and gas exploration and production; developments in nonregulatory oil and gas law; recent developments in oil and gas taxation; entity selection - an experience in alchemy - a comparison of corporations, partnerships, and joint ventures; foreign money and US oil and gas - tax considerations; 1978 legislative developments in oil and gas taxation; and recapture of intangibles under section 1254. (DC)« less

Effect of hysteretic and non-hysteretic negative capacitance on tunnel FETs DC performance

NASA Astrophysics Data System (ADS)

Saeidi, Ali; Jazaeri, Farzan; Stolichnov, Igor; Luong, Gia V.; Zhao, Qing-Tai; Mantl, Siegfried; Ionescu, Adrian M.

2018-03-01

This work experimentally demonstrates that the negative capacitance effect can be used to significantly improve the key figures of merit of tunnel field effect transistor (FET) switches. In the proposed approach, a matching condition is fulfilled between a trained-polycrystalline PZT capacitor and the tunnel FET (TFET) gate capacitance fabricated on a strained silicon-nanowire technology. We report a non-hysteretic switch configuration by combining a homojunction TFET and a negative capacitance effect booster, suitable for logic applications, for which the on-current is increased by a factor of 100, the transconductance by 2 orders of magnitude, and the low swing region is extended. The operation of a hysteretic negative capacitance TFET, when the matching condition for the negative capacitance is fulfilled only in a limited region of operation, is also reported and discussed. In this late case, a limited improvement in the device performance is observed. Overall, the paper demonstrates the main beneficial effects of negative capacitance on TFETs are the overdrive and transconductance amplification, which exactly address the most limiting performances of current TFETs.

Biodegradation: Updating the concepts of control for microbial cleanup in contaminated aquifers.

PubMed

Meckenstock, Rainer U; Elsner, Martin; Griebler, Christian; Lueders, Tillmann; Stumpp, Christine; Aamand, Jens; Agathos, Spiros N; Albrechtsen, Hans-Jørgen; Bastiaens, Leen; Bjerg, Poul L; Boon, Nico; Dejonghe, Winnie; Huang, Wei E; Schmidt, Susanne I; Smolders, Erik; Sørensen, Sebastian R; Springael, Dirk; van Breukelen, Boris M

2015-06-16

Biodegradation is one of the most favored and sustainable means of removing organic pollutants from contaminated aquifers but the major steering factors are still surprisingly poorly understood. Growing evidence questions some of the established concepts for control of biodegradation. Here, we critically discuss classical concepts such as the thermodynamic redox zonation, or the use of steady state transport scenarios for assessing biodegradation rates. Furthermore, we discuss if the absence of specific degrader populations can explain poor biodegradation. We propose updated perspectives on the controls of biodegradation in contaminant plumes. These include the plume fringe concept, transport limitations, and transient conditions as currently underestimated processes affecting biodegradation.

Parent-focused child maltreatment prevention: improving assessment, intervention, and dissemination with technology.

PubMed

Self-Brown, Shannon; Whitaker, Daniel J

2008-11-01

The goal of this article is to examine how technology has been and can be utilized to enhance parent-focused child maltreatment (CM) prevention efforts. The authors begin with a brief discussion of the current state of the CM prevention field. In the sections that follow, they review studies that have examined the use of technology across three facets of prevention: identification of CM, administration/augmentation of CM prevention programs, and broad dissemination and implementation of evidenced-based CM prevention programs. They conclude with a discussion of limitations and problems related to the use of technology as a tool to enhance CM prevention and future directions.

Decomposability and scalability in space-based observatory scheduling

NASA Technical Reports Server (NTRS)

Muscettola, Nicola; Smith, Stephen F.

1992-01-01

In this paper, we discuss issues of problem and model decomposition within the HSTS scheduling framework. HSTS was developed and originally applied in the context of the Hubble Space Telescope (HST) scheduling problem, motivated by the limitations of the current solution and, more generally, the insufficiency of classical planning and scheduling approaches in this problem context. We first summarize the salient architectural characteristics of HSTS and their relationship to previous scheduling and AI planning research. Then, we describe some key problem decomposition techniques supported by HSTS and underlying our integrated planning and scheduling approach, and we discuss the leverage they provide in solving space-based observatory scheduling problems.

Precision medicine in pediatric oncology: Lessons learned and next steps.

PubMed

Mody, Rajen J; Prensner, John R; Everett, Jessica; Parsons, D Williams; Chinnaiyan, Arul M

2017-03-01

The maturation of genomic technologies has enabled new discoveries in disease pathogenesis as well as new approaches to patient care. In pediatric oncology, patients may now receive individualized genomic analysis to identify molecular aberrations of relevance for diagnosis and/or treatment. In this context, several recent clinical studies have begun to explore the feasibility and utility of genomics-driven precision medicine. Here, we review the major developments in this field, discuss current limitations, and explore aspects of the clinical implementation of precision medicine, which lack consensus. Lastly, we discuss ongoing scientific efforts in this arena, which may yield future clinical applications. © 2016 Wiley Periodicals, Inc.

Precision medicine in pediatric oncology: Lessons learned and next steps

PubMed Central

Mody, Rajen J.; Prensner, John R.; Everett, Jessica; Parsons, D. Williams; Chinnaiyan, Arul M.

2017-01-01

The maturation of genomic technologies has enabled new discoveries in disease pathogenesis as well as new approaches to patient care. In pediatric oncology, patients may now receive individualized genomic analysis to identify molecular aberrations of relevance for diagnosis and/or treatment. In this context, several recent clinical studies have begun to explore the feasibility and utility of genomics-driven precision medicine. Here, we review the major developments in this field, discuss current limitations, and explore aspects of the clinical implementation of precision medicine, which lack consensus. Lastly, we discuss ongoing scientific efforts in this arena, which may yield future clinical applications. PMID:27748023

Amorphous or Crystalline? A Comparison of Particle Engineering Methods and Selection.

PubMed

Thakkar, Sachin G; Fathe, Kristin; Smyth, Hugh D C

2015-01-01

This review is intended to provide a critical account of the current goals and technologies of particle engineering regarding the production of crystalline and amorphous particles. The technologies discussed here cover traditional crystallization technologies, supercritical fluid technologies, spray drying, controlled solvent crystallization, and sonocrystallization. Also recent advancements in particle engineering including spray freezing into liquid, thin-film freeze-drying, PRINT technology are presented. The paper also examines the merits and limitations of these technologies with respect to their methods of characterization. Additionally a section discussing the utility of creating amorphous and crystalline formulation approaches in regards to bioavailability and utility in formulation is presented.

Mechanisms underlying brain monitoring during anesthesia: limitations, possible improvements, and perspectives

PubMed Central

2016-01-01

Currently, anesthesiologists use clinical parameters to directly measure the depth of anesthesia (DoA). This clinical standard of monitoring is often combined with brain monitoring for better assessment of the hypnotic component of anesthesia. Brain monitoring devices provide indices allowing for an immediate assessment of the impact of anesthetics on consciousness. However, questions remain regarding the mechanisms underpinning these indices of hypnosis. By briefly describing current knowledge of the brain's electrical activity during general anesthesia, as well as the operating principles of DoA monitors, the aim of this work is to simplify our understanding of the mathematical processes that allow for translation of complex patterns of brain electrical activity into dimensionless indices. This is a challenging task because mathematical concepts appear remote from clinical practice. Moreover, most DoA algorithms are proprietary algorithms and the difficulty of exploring the inner workings of mathematical models represents an obstacle to accurate simplification. The limitations of current DoA monitors — and the possibility for improvement — as well as perspectives on brain monitoring derived from recent research on corticocortical connectivity and communication are also discussed. PMID:27066200

Non-pharmacological treatment options for refractory epilepsy: an overview of human treatment modalities and their potential utility in dogs.

PubMed

Martlé, Valentine; Van Ham, Luc; Raedt, Robrecht; Vonck, Kristl; Boon, Paul; Bhatti, Sofie

2014-03-01

Refractory epilepsy is a common disorder both in humans and dogs and treatment protocols are difficult to optimise. In humans, different non-pharmacological treatment modalities currently available include surgery, the ketogenic diet and neurostimulation. Surgery leads to freedom from seizures in 50-75% of patients, but requires strict patient selection. The ketogenic diet is indicated in severe childhood epilepsies, but efficacy is limited and long-term compliance can be problematic. In the past decade, various types of neurostimulation have emerged as promising treatment modalities for humans with refractory epilepsy. Currently, none of these treatment options are used in routine daily clinical practice to treat dogs with the condition. Since many dogs with poorly controlled seizures do not survive, the search for alternative treatment options for canine refractory epilepsy should be prioritised. This review provides an overview of non-pharmacological treatment options for human refractory epilepsy. The current knowledge and limitations of these treatments in canine refractory epilepsy is also discussed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Current advances and future perspectives in extrusion-based bioprinting.

PubMed

Ozbolat, Ibrahim T; Hospodiuk, Monika

2016-01-01

Extrusion-based bioprinting (EBB) is a rapidly growing technology that has made substantial progress during the last decade. It has great versatility in printing various biologics, including cells, tissues, tissue constructs, organ modules and microfluidic devices, in applications from basic research and pharmaceutics to clinics. Despite the great benefits and flexibility in printing a wide range of bioinks, including tissue spheroids, tissue strands, cell pellets, decellularized matrix components, micro-carriers and cell-laden hydrogels, the technology currently faces several limitations and challenges. These include impediments to organ fabrication, the limited resolution of printed features, the need for advanced bioprinting solutions to transition the technology bench to bedside, the necessity of new bioink development for rapid, safe and sustainable delivery of cells in a biomimetically organized microenvironment, and regulatory concerns to transform the technology into a product. This paper, presenting a first-time comprehensive review of EBB, discusses the current advancements in EBB technology and highlights future directions to transform the technology to generate viable end products for tissue engineering and regenerative medicine. Copyright © 2015 Elsevier Ltd. All rights reserved.

The genome editing toolbox: a spectrum of approaches for targeted modification.

PubMed

Cheng, Joseph K; Alper, Hal S

2014-12-01

The increase in quality, quantity, and complexity of recombinant products heavily drives the need to predictably engineer model and complex (mammalian) cell systems. However, until recently, limited tools offered the ability to precisely manipulate their genomes, thus impeding the full potential of rational cell line development processes. Targeted genome editing can combine the advances in synthetic and systems biology with current cellular hosts to further push productivity and expand the product repertoire. This review highlights recent advances in targeted genome editing techniques, discussing some of their capabilities and limitations and their potential to aid advances in pharmaceutical biotechnology. Copyright © 2014 Elsevier Ltd. All rights reserved.

Environmental aspects of the TROLL terminal design

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

Weeks, D.J.

1996-12-31

Norway, in common with many countries nowadays, is very protective of its environment. This consciousness and responsibility are reflected by the strict limits on air pollution, in particular noise, and hydrocarbon contaminant levels in discharged water that were imposed for the TROLL terminal design. The capacity of the terminal and the size of its equipment have necessitated new research in the field of noise prediction some of which conflicts with current industry beliefs. This paper discusses some of the engineered solutions to in-plant and community noise abatement and describes the water treatment facilities installed to meet hydrocarbon discharge limits ofmore » 5 mg/l.« less

Overcoming limitations of model-based diagnostic reasoning systems

NASA Technical Reports Server (NTRS)

Holtzblatt, Lester J.; Marcotte, Richard A.; Piazza, Richard L.

1989-01-01

The development of a model-based diagnostic system to overcome the limitations of model-based reasoning systems is discussed. It is noted that model-based reasoning techniques can be used to analyze the failure behavior and diagnosability of system and circuit designs as part of the system process itself. One goal of current research is the development of a diagnostic algorithm which can reason efficiently about large numbers of diagnostic suspects and can handle both combinational and sequential circuits. A second goal is to address the model-creation problem by developing an approach for using design models to construct the GMODS model in an automated fashion.

Theory of mind: mechanisms, methods, and new directions

PubMed Central

Byom, Lindsey J.; Mutlu, Bilge

2013-01-01

Theory of Mind (ToM) has received significant research attention. Traditional ToM research has provided important understanding of how humans reason about mental states by utilizing shared world knowledge, social cues, and the interpretation of actions; however, many current behavioral paradigms are limited to static, “third-person” protocols. Emerging experimental approaches such as cognitive simulation and simulated social interaction offer opportunities to investigate ToM in interactive, “first-person” and “second-person” scenarios while affording greater experimental control. The advantages and limitations of traditional and emerging ToM methodologies are discussed with the intent of advancing the understanding of ToM in socially mediated situations. PMID:23964218

Detection limit of a VCO based detection chain dedicated to particles recognition and tracking

NASA Astrophysics Data System (ADS)

Coulié, K.; Rahajandraibe, W.; Aziza, H.; Micolau, G.; Vauché, R.

2018-01-01

A particle detection chain based on CMOS-SOI VCO circuit is presented. The solution is used for the recognition and the tracking of a given particle at circuit level. TCAD simulation of the detector has been performed on a 3×3 matrix of diodes based detector for particles recognition and tracking. The current response of the detector has been used for a case study in order to determine the ability of the chain to recognize an alpha particle crossing a 3×3 detection cell. The detection limit of the proposed solution is investigated and discussed in this paper.

Resonant inelastic soft x-ray scattering of CdS: a two-dimensional electronic structure map approach

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

Weinhardt, L.; Fuchs, O.; Fleszar, A.

2008-09-24

Resonant inelastic x-ray scattering (RIXS) with soft x-rays is uniquely suited to study the elec-tronic structure of a variety of materials, but is currently limited by low (fluorescence yield) count rates. This limitation is overcome with a new high-transmission spectrometer that allows to measure soft x-ray RIXS"maps." The S L2,3 RIXS map of CdS is discussed and compared with density functional calculations. The map allows the extraction of decay channel-specific"absorp-tion spectra," giving detailed insight into the wave functions of occupied and unoccupied elec-tronic states.

Is IPT Time-Limited Psychodynamic Psychotherapy?

PubMed Central

Markowitz, John C.; Svartberg, Martin; Swartz, Holly A.

1998-01-01

Interpersonal psychotherapy (IPT) has sometimes but not always been considered a psychodynamic psychotherapy. The authors discuss similarities and differences between IPT and short-term psychodynamic psychotherapy (STPP), comparing eight aspects: 1) time limit, 2) medical model, 3) dual goals of solving interpersonal problems and syndromal remission, 4) interpersonal focus on the patient solving current life problems, 5) specific techniques, 6) termination, 7) therapeutic stance, and 8) empirical support. The authors then apply both approaches to a case example of depression. They conclude that despite overlaps and similarities, IPT is distinct from STPP.(The Journal of Psychotherapy Practice and Research 1998; 7:185–195) PMID:9631340

A new approach to high-efficiency multi-band-gap solar cells

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

Barnham, K.W.J.; Duggan, G.

1990-04-01

The advantages of using multi-quantum-well or superlattice systems as the absorbers in concentrator solar cells are discussed. By adjusting the quantum-well width, an effective band-gap variation that covers the high-efficiency region of the solar spectrum can be obtained. Higher efficiencies should result from the ability to optimize separately current and voltage generating factors. Suitable structures to ensure good carrier separation and collection and to obtain higher open-circuit voltages are presented using the (AlGa)As/GaAs/(InGa)As system. Efficiencies above existing single-band-gap limits should be achievable, with upper limits in excess of 40%.

Novel Functional Genomics Approaches: A Promising Future in the Combat Against Plant Viruses.

PubMed

Fondong, Vincent N; Nagalakshmi, Ugrappa; Dinesh-Kumar, Savithramma P

2016-10-01

Advances in functional genomics and genome editing approaches have provided new opportunities and potential to accelerate plant virus control efforts through modification of host and viral genomes in a precise and predictable manner. Here, we discuss application of RNA-based technologies, including artificial micro RNA, transacting small interfering RNA, and Cas9 (clustered regularly interspaced short palindromic repeat-associated protein 9), which are currently being successfully deployed in generating virus-resistant plants. We further discuss the reverse genetics approach, targeting induced local lesions in genomes (TILLING) and its variant, known as EcoTILLING, that are used in the identification of plant virus recessive resistance gene alleles. In addition to describing specific applications of these technologies in plant virus control, this review discusses their advantages and limitations.

Cholinesterase inhibitors in Alzheimer's disease and Lewy body spectrum disorders: the emerging pharmacogenetic story

PubMed Central

2009-01-01

This review provides an update on the current state of pharmacogenetic research in the treatment of Alzheimer's disease (AD) and Lewy body disease (LBD) as it pertains to the use of cholinesterase inhibitors (ChEI). AD and LBD are first reviewed from clinical and pathophysiological perspectives. This is followed by a discussion of ChEIs used in the symptomatic treatment of these conditions, focusing on their unique and overlapping pharmacokinetic and pharmacodynamic profiles, which can be used to identify candidate genes for pharmacogenetics studies. The literature published to date is then reviewed and limitations are discussed. This is followed by a discussion of potential endophenotypes which may help to refine future pharmacogenetic studies of response and adverse effects to ChEIs. PMID:20038497

Magnetic field strengths in high-redshift galaxies - Can the galactic dynamo be tested?

NASA Technical Reports Server (NTRS)

Perry, Judith J.; Watson, Alan M.; Kronberg, Philipp P.

1993-01-01

The hypothesis that the population of strong H I absorption systems is responsible for a significant excess Faraday rotation measure in quasars is discussed, and it is concluded that the case is unproved, in contrast to a recent analysis by Wolf et al. (1991). The limitations and pitfalls inherent in attempts to derive firm magnetic field strengths from the existing integrated rotation measures of quasars are discussed, and it is shown that although it is premature to use integrated quasar rotation measures to either confirm or rule out particular mechanisms of magnetic field amplification in galaxy disks, the present observations may call for reexamination of current theories of large-scale magnetic field generation. The sources of rotation measure in the double quasar 0957+561 are also discussed.

Federal Mechanisms to Support Intervention Dissemination.

PubMed

Diana, Augusto; Bennett, Nicole

2015-01-01

This paper examines federal mechanisms that support program developers and researchers in disseminating effective interventions for public benefit. The purpose of this paper is not to discuss the dissemination of intervention research (i.e., how to inform stakeholders about research findings), nor is it intended to discuss the research of intervention dissemination (i.e., what is the best approach to disseminate an intervention). Rather, the paper discusses the challenges specific to finding pathways to disseminate an intervention and describes federal opportunities to support intervention dissemination. Three specific mechanisms are discussed: Federal Registries of Evidence-Based Programs, the Tiered Evidence Grant Programs, and the Small Business Innovative Research (SBIR) and the Small Technology Transfer Research (STTR) programs. The article presents some limitations associated with federal mechanisms for dissemination of effective interventions, but is intended to highlight current and future opportunities they may offer. © 2015 Wiley Periodicals, Inc.

Benefits and limitations of prenatal screening for Prader-Willi syndrome.

PubMed

Butler, Merlin G

2017-01-01

This review summarizes the status of genetic laboratory testing in Prader-Willi syndrome (PWS) with different genetic subtypes, most often a paternally derived 15q11-q13 deletion and discusses benefits and limitations related to prenatal screening. Medical literature was searched for prenatal screening and genetic laboratory testing methods in use or under development and discussed in relationship to PWS. Genetic testing includes six established laboratory diagnostic approaches for PWS with direct application to prenatal screening. Ultrasonographic, obstetric and cytogenetic reports were summarized in relationship to the cause of PWS and identification of specific genetic subtypes including maternal disomy 15. Advances in genetic technology were described for diagnosing PWS specifically DNA methylation and high-resolution chromosomal SNP microarrays as current tools for genetic screening and incorporating next generation DNA sequencing for noninvasive prenatal testing (NIPT) using cell-free fetal DNA. Positive experiences are reported with NIPT for detection of numerical chromosomal problems (aneuploidies) but not for structural problems (microdeletions). These reports will be discussed along with future directions for genetic screening of PWS. In summary, this review describes and discusses the status of established and ongoing genetic testing options for PWS applicable in prenatal screening including NIPT and future directions for early diagnosis in PWS. © 2016 John Wiley & Sons, Ltd. © 2016 John Wiley & Sons, Ltd.

Simulations of stress evolution and the current density scaling of electromigration-induced failure times in pure and alloyed interconnects

NASA Astrophysics Data System (ADS)

Park, Young-Joon; Andleigh, Vaibhav K.; Thompson, Carl V.

1999-04-01

An electromigration model is developed to simulate the reliability of Al and Al-Cu interconnects. A polynomial expression for the free energy of solution by Murray [Int. Met. Rev. 30, 211 (1985)] was used to calculate the chemical potential for Al and Cu while the diffusivities were defined based on a Cu-trapping model by Rosenberg [J. Vac. Sci. Technol. 9, 263 (1972)]. The effects of Cu on stress evolution and lifetime were investigated in all-bamboo and near-bamboo stud-to-stud structures. In addition, the significance of the effect of mechanical stress on the diffusivity of both Al and Cu was determined in all-bamboo and near-bamboo lines. The void nucleation and growth process was simulated in 200 μm, stud-to-stud lines. Current density scaling behavior for void-nucleation-limited failure and void-growth-limited failure modes was simulated in long, stud-to-stud lines. Current density exponents of both n=2 for void nucleation and n=1 for void growth failure modes were found in both pure Al and Al-Cu lines. Limitations of the most widely used current density scaling law (Black's equation) in the analysis of the reliability of stud-to-stud lines are discussed. By modifying the input materials properties used in this model (when they are known), this model can be adapted to predict the reliability of other interconnect materials such as pure Cu and Cu alloys.

Status of high temperature superconductor cable and fault current limiter projects at American Superconductor

NASA Astrophysics Data System (ADS)

Maguire, J. F.; Yuan, J.

2009-10-01

This paper will describe the status of three key programs currently underway at American Superconductor Corp. The first program is the LIPA project which is a transmission voltage high temperature superconducting cable program, with funding support from the US Department of Energy. The 600 m cable, capable of carrying 574 MVA, was successfully installed and commissioned in LIPA grid on April 22, 2008. An overview of the project, system level design details and operational data will be provided. In addition, the status of the newly awarded LIPA II project will be described. The second program is Project Hydra, with funding support from the US Department of Homeland Security, to design, develop and demonstrate an HTS cable with fault current limiting functionality. The cable is 300 m long and is being designed to carry 96 MVA at a distribution level voltage of 13.8 kV. The cable will be permanently installed and energized in Manhattan, New York in 2010. The initial status of Project Hydra will be presented. The final program to be discussed is a transmission voltage, high temperature superconducting fault current limiter funded by the US DOE. The project encompasses the design, construction and test of a 115 kV FCL for power transmission within a time frame of 4-5 years. Installation and testing are planned for a Southern California Edison substation. A project overview and progress under the first phase will be reported.

Intermittent fasting and cardiovascular disease: current evidence and unresolved questions.

PubMed

Tinsley, Grant M; Horne, Benjamin D

2018-01-01

Intermittent fasting has produced a variety of beneficial health effects in animal models, although high-quality research in humans has been limited. This special report examines current evidences for intermittent fasting in humans, discusses issues that require further examination, and recommends new research that can improve the knowledge base in this emerging research area. While potentially useful for health improvement, intermittent fasting requires further study prior to widespread implementation for health purposes. Randomized, longer-term studies are needed to determine whether using intermittent fasting as a lifestyle rather than a diet is feasible and beneficial for the health of some members of the human population.

Principles of treatment for vaccine-associated sarcomas.

PubMed

Novosad, C Andrew

2003-05-01

In the last decade, there has been a great deal of information surrounding the etiology, diagnosis, and treatment of feline vaccine-associated sarcomas. The presence of a mass in areas used for subcutaneous or intramuscular injections should alert the clinician to the possibility of a vaccine-associated sarcoma. Early detection and subsequent treatment is paramount to limit local invasion and distant metastasis. The current data are suggesting that a team approach with multi-modality therapy is the appropriate way to address this disease. In the following article, we will discuss the history/incidence, pathology, diagnosis, and current treatment options, which include a combination of surgery, radiation, and chemotherapy for vaccine-associated sarcomas.

Nutritional Status and Diet in Cancer Prevention.

PubMed

Bail, Jennifer; Meneses, Karen; Demark-Wahnefried, Wendy

2016-08-01

To discuss the relationship between weight management and diet and cancer prevention, current nutritional guidelines, and evidence-based strategies to reduce cancer risk. Current nutritional guidelines, journal articles published between 2012 and 2015, and internet resources. Evidence indicates that attaining and/or maintaining a healthy weight and adopting a diet that is primarily plant-based, low in red and processed meats, simple sugars, and refined carbohydrates, limits alcohol, and relies on food for nutrients can aid in preventing cancer. Nurses can take the lead to educate patients and families about weight management and diet and to promote adherence to nutritional guidelines. Copyright © 2016 Elsevier Inc. All rights reserved.

Recent advances in bioelectric prostheses

PubMed Central

Pasquina, Paul F.; Perry, Briana N.; Miller, Matthew E.; Ling, Geoffrey S.F.; Tsao, Jack W.

2015-01-01

Summary Worldwide prevalence of amputation has created an increasing demand for improved upper and lower extremity prostheses. Current prosthetics are often uncomfortable and difficult to control and provide limited functional restoration. Moreover, the inability to normalize anthropomorphic biomechanics with a prosthesis increases one's risk of developing long-term health risks such as arthritis, skin breakdown, and pain. Recent advances in bionic prosthetic development hold great promise for rehabilitation and improving quality of life with limb loss. This brief review discusses the current state of advanced prostheses, the integration of robotics in the care of individuals with major limb amputation, and some innovative surgical techniques that are being explored for clinical feasibility. PMID:29443190

Computer games: a double-edged sword?

PubMed

Sun, De-Lin; Ma, Ning; Bao, Min; Chen, Xang-Chuan; Zhang, Da-Ren

2008-10-01

Excessive computer game playing (ECGP) has already become a serious social problem. However, limited data from experimental lab studies are available about the negative consequences of ECGP on players' cognitive characteristics. In the present study, we compared three groups of participants (current ECGP participants, previous ECGP participants, and control participants) on a Multiple Object Tracking (MOT) task. The previous ECGP participants performed significantly better than the control participants, which suggested a facilitation effect of computer games on visuospatial abilities. Moreover, the current ECGP participants performed significantly worse than the previous ECGP participants. This more important finding indicates that ECGP may be related to cognitive deficits. Implications of this study are discussed.

Signatures of particle acceleration at SN 1987A

NASA Technical Reports Server (NTRS)

Gaisser, T. K.; Stanev, Todor; Harding, Alice K.

1989-01-01

At least eight experiments are currently monitoring SN 1987A for photons or neutrinos with energies in the TeV range or higher. Observation of such signals would indicate that the supernova is the site of acceleration of charged particles to even higher energies. The way that the acceleration might occur is discussed, and the prospects for detection of such signals in light of current limits on power in the supernova from sources other than the nickel-cobalt-iron decay chain are evaluated. It is pointed out that signals of particle acceleration may show up in continuum MeV gamma rays as well as in the 100 MeV range.

Novel biotherapies are needed in youth mental health.

PubMed

Amminger, G Paul; Berger, Maximus; Rice, Simon M; Davey, Christopher G; Schäfer, Miriam R; McGorry, Patrick D

2017-04-01

Adverse effects and lack of efficacy in a significant number of patients limit pharmaceutical interventions in youth psychiatry. This is exemplified by the fact that no medication is currently approved for the treatment of non-OCD anxiety disorders or major depressive disorder in young people younger than 18 years of age in Australia. Here, emerging biological therapies for youth with mental health problems are discussed. There is an urgent need for more research into biological interventions with acceptable risk-benefit balances. Omega-3 fatty acids, cannabidiol and N-acetylcysteine are currently being evaluated. If initial findings are confirmed, they may offer alternatives with more benign side-effect profiles than existing treatments.

Current Strategies for the Detoxification of Jatropha curcas Seed Cake: A Review.

PubMed

Gomes, Taisa G; Hadi, Sámed I I A; Costa Alves, Gabriel S; Mendonça, Simone; De Siqueira, Felix G; Miller, Robert N G

2018-03-21

Jatropha curcas is an important oilseed plant, with considerable potential in the development of biodiesel. Although Jatropha seed cake, the byproduct of oil extraction, is a residue rich in nitrogen, phosphorus, potassium, and carbon, with high protein content suitable for application in animal feed, the presence of toxic phorbol esters limits its application in feed supplements and fertilizers. This review summarizes the current methods available for detoxification of this residue, based upon chemical, physical, biological, or combined processes. The advantages and disadvantages of each process are discussed, and future directions involving genomic and proteomic approaches for advancing our understanding of biodegradation processes involving microorganisms are highlighted.

Spectrum and orbit conservation as a factor in future mobile satellite system design

NASA Technical Reports Server (NTRS)

Bowen, Robert R.

1990-01-01

Access to the radio spectrum and geostationary orbit is essential to current and future mobile satellite systems. This access is difficult to obtain for current systems, and may be even more so for larger future systems. In this environment, satellite systems that minimize the amount of spectrum orbit resource required to meet a specific traffic requirement are essential. Several spectrum conservation techniques are discussed, some of which are complementary to designing the system at minimum cost. All may need to be implemented to the limits of technological feasibility if network growth is not to be constrained because of the lack of available spectrum-orbit resource.

Development of a switched integrator amplifier for high-accuracy optical measurements.

PubMed

Mountford, John; Porrovecchio, Geiland; Smid, Marek; Smid, Radislav

2008-11-01

In the field of low flux optical measurements, the development and use of large area silicon detectors is becoming more frequent. The current/voltage conversion of their photocurrent presents a set of problems for traditional transimpedance amplifiers. The switched integration principle overcomes these limitations. We describe the development of a fully characterized current-voltage amplifier using the switched integrator technique. Two distinct systems have been developed in parallel at the United Kingdom's National Physical Laboratory (NPL) and Czech Metrology Institute (CMI) laboratories. We present the circuit theory and best practice in the design and construction of switched integrators. In conclusion the results achieved and future developments are discussed.

Screening strategies to identify new chemical diversity for drug development to treat kinetoplastid infections.

PubMed

Don, Rob; Ioset, Jean-Robert

2014-01-01

The Drugs for Neglected Diseases initiative (DNDi) has defined and implemented an early discovery strategy over the last few years, in fitting with its virtual R&D business model. This strategy relies on a medium- to high-throughput phenotypic assay platform to expedite the screening of compound libraries accessed through its collaborations with partners from the pharmaceutical industry. We review the pragmatic approaches used to select compound libraries for screening against kinetoplastids, taking into account screening capacity. The advantages, limitations and current achievements in identifying new quality series for further development into preclinical candidates are critically discussed, together with attractive new approaches currently under investigation.

The effects of religiosity on psychopathology in emerging adults: intrinsic versus extrinsic religiosity.

PubMed

Power, Leah; McKinney, Cliff

2014-10-01

Recent research has suggested that religion may play an important role in determining mental health. Although research has examined the effects of religiosity on specific types of psychopathology, less research has examined psychopathology broadly in the context of particular aspects of religion. Thus, the current study examined intrinsic and extrinsic religiosity and a range of psychopathology in 486 emerging adult college students. Results of a MANOVA indicated a main effect for intrinsic religiosity on a range of psychopathology and an interaction effect between intrinsic and extrinsic religiosity on antisocial personality problems. Implications and limitations of the current study are discussed.

Chocolate and coronary heart disease: a systematic review.

PubMed

Khawaja, Owais; Gaziano, J Michael; Djoussé, Luc

2011-12-01

Coronary heart disease (CHD) is the leading cause of death in the United States. The high content of polyphenols and flavonoids present in cocoa has been reported to play an important protective role in the development of CHD. Although studies have demonstrated beneficial effects of chocolate on endothelial function, blood pressure, serum lipids, insulin resistance, and platelet function, it is unclear whether chocolate consumption influences the risk of CHD. This article reviews current evidence on the effects of cocoa/chocolate on clinical and subclinical CHD, CHD risk factors, and potential biologic mechanisms. It also discusses major limitations of currently available data and future directions in the field.

Localized Surface Plasmon Resonance Biosensing: Current Challenges and Approaches

PubMed Central

Unser, Sarah; Bruzas, Ian; He, Jie; Sagle, Laura

2015-01-01

Localized surface plasmon resonance (LSPR) has emerged as a leader among label-free biosensing techniques in that it offers sensitive, robust, and facile detection. Traditional LSPR-based biosensing utilizes the sensitivity of the plasmon frequency to changes in local index of refraction at the nanoparticle surface. Although surface plasmon resonance technologies are now widely used to measure biomolecular interactions, several challenges remain. In this article, we have categorized these challenges into four categories: improving sensitivity and limit of detection, selectivity in complex biological solutions, sensitive detection of membrane-associated species, and the adaptation of sensing elements for point-of-care diagnostic devices. The first section of this article will involve a conceptual discussion of surface plasmon resonance and the factors affecting changes in optical signal detected. The following sections will discuss applications of LSPR biosensing with an emphasis on recent advances and approaches to overcome the four limitations mentioned above. First, improvements in limit of detection through various amplification strategies will be highlighted. The second section will involve advances to improve selectivity in complex media through self-assembled monolayers, “plasmon ruler” devices involving plasmonic coupling, and shape complementarity on the nanoparticle surface. The following section will describe various LSPR platforms designed for the sensitive detection of membrane-associated species. Finally, recent advances towards multiplexed and microfluidic LSPR-based devices for inexpensive, rapid, point-of-care diagnostics will be discussed. PMID:26147727

Limits in point to point resolution of MOS based pixels detector arrays

NASA Astrophysics Data System (ADS)

Fourches, N.; Desforge, D.; Kebbiri, M.; Kumar, V.; Serruys, Y.; Gutierrez, G.; Leprêtre, F.; Jomard, F.

2018-01-01

In high energy physics point-to-point resolution is a key prerequisite for particle detector pixel arrays. Current and future experiments require the development of inner-detectors able to resolve the tracks of particles down to the micron range. Present-day technologies, although not fully implemented in actual detectors, can reach a 5-μm limit, this limit being based on statistical measurements, with a pixel-pitch in the 10 μm range. This paper is devoted to the evaluation of the building blocks for use in pixel arrays enabling accurate tracking of charged particles. Basing us on simulations we will make here a quantitative evaluation of the physical and technological limits in pixel size. Attempts to design small pixels based on SOI technology will be briefly recalled here. A design based on CMOS compatible technologies that allow a reduction of the pixel size below the micrometer is introduced here. Its physical principle relies on a buried carrier-localizing collecting gate. The fabrication process needed by this pixel design can be based on existing process steps used in silicon microelectronics. The pixel characteristics will be discussed as well as the design of pixel arrays. The existing bottlenecks and how to overcome them will be discussed in the light of recent ion implantation and material characterization experiments.

Radiation risk estimation and its application to human beings in space.

PubMed

Sinclair, W K

1984-01-01

The number of human beings likely to spend time in space will increase as time goes on. While exposures vary according to missions, orbits, shielding, etc., an average space radiation fluence (ignoring solar flares, radiation belts and anomalous regions in space) in locations close to earth is about 10 rad/year with a quality factor of about 5.5. The potential effects of exposure to these fluences include both non-stochastic effects and stochastic effects (cancer and genetic damage). Non-stochastic effects, damage to the lens of the eye, bone marrow or gonads, can be avoided by keeping radiation limits below threshold values. Stochastic effects imply risk at all levels. The magnitude of these risks has been discussed in a number of reports by the UNSCEAR Committee and the BEIR Committee in the USA during 1970-1980. The uncertainties associated with these risks and information which has become available since the last BEIR report is discussed. In considering reasonable limits for exposure in space, acceptable levels for stochastic risks must be based on appropriate comparisons. In view of the limited term of duty of most space workers, a lifetime limit may be appropriate. This lifetime limit might be comparable in terms of risks with limits for radiation workers on the ground but received at a higher annual rate for a shorter time. These and other approaches are expected to be considered by an NCRP Committee currently examining the problem of space radiation hazards.

Low-frequency electrical dosimetry: research agenda of the IEEE International Committee on Electromagnetic Safety.

PubMed

Reilly, J Patrick; Hirata, Akimasa

2016-06-21

This article treats unsettled issues in the use of numerical models of electrical dosimetry as applied to international limits on human exposure to low-frequency (typically  <  100 kHz) electromagnetic fields and contact current. The perspective in this publication is that of Subcommittee 6 of IEEE-ICES (International Committee on Electromagnetic Safety) Technical Committee 95. The paper discusses 25 issues needing attention, fitting into three general categories: induction models; electrostimulation models; and human exposure limits. Of these, 9 were voted as 'high priority' by members of Subcommittee 6. The list is presented as a research agenda for refinements in numerical modeling with applications to human exposure limits. It is likely that such issues are also important in medical and electrical product safety design applications.

Origins and challenges of viral dark matter.

PubMed

Krishnamurthy, Siddharth R; Wang, David

2017-07-15

The accurate classification of viral dark matter - metagenomic sequences that originate from viruses but do not align to any reference virus sequences - is one of the major obstacles in comprehensively defining the virome. Depending on the sample, viral dark matter can make up from anywhere between 40 and 90% of sequences. This review focuses on the specific nature of dark matter as it relates to viral sequences. We identify three factors that contribute to the existence of viral dark matter: the divergence and length of virus sequences, the limitations of alignment based classification, and limited representation of viruses in reference sequence databases. We then discuss current methods that have been developed to at least partially circumvent these limitations and thereby reduce the extent of viral dark matter. Copyright © 2017 Elsevier B.V. All rights reserved.

Exploring the validity and limitations of the Mott-Gurney law for charge-carrier mobility determination of semiconducting thin-films.

PubMed

Röhr, Jason A; Moia, Davide; Haque, Saif A; Kirchartz, Thomas; Nelson, Jenny

2018-03-14

Using drift-diffusion simulations, we investigate the voltage dependence of the dark current in single carrier devices typically used to determine charge-carrier mobilities. For both low and high voltages, the current increases linearly with the applied voltage. Whereas the linear current at low voltages is mainly due to space charge in the middle of the device, the linear current at high voltage is caused by charge-carrier saturation due to a high degree of injection. As a consequence, the current density at these voltages does not follow the classical square law derived by Mott and Gurney, and we show that for trap-free devices, only for intermediate voltages, a space-charge-limited drift current can be observed with a slope that approaches a value of two. We show that, depending on the thickness of the semiconductor layer and the size of the injection barriers, the two linear current-voltage regimes can dominate the whole voltage range, and the intermediate Mott-Gurney regime can shrink or disappear. In this case, which will especially occur for thicknesses and injection barriers typical of single-carrier devices used to probe organic semiconductors, a meaningful analysis using the Mott-Gurney law will become unachievable, because a square-law fit can no longer be achieved, resulting in the mobility being substantially underestimated. General criteria for when to expect deviations from the Mott-Gurney law when used for analysis of intrinsic semiconductors are discussed.

Exploring the validity and limitations of the Mott-Gurney law for charge-carrier mobility determination of semiconducting thin-films

NASA Astrophysics Data System (ADS)

Röhr, Jason A.; Moia, Davide; Haque, Saif A.; Kirchartz, Thomas; Nelson, Jenny

2018-03-01

Using drift-diffusion simulations, we investigate the voltage dependence of the dark current in single carrier devices typically used to determine charge-carrier mobilities. For both low and high voltages, the current increases linearly with the applied voltage. Whereas the linear current at low voltages is mainly due to space charge in the middle of the device, the linear current at high voltage is caused by charge-carrier saturation due to a high degree of injection. As a consequence, the current density at these voltages does not follow the classical square law derived by Mott and Gurney, and we show that for trap-free devices, only for intermediate voltages, a space-charge-limited drift current can be observed with a slope that approaches a value of two. We show that, depending on the thickness of the semiconductor layer and the size of the injection barriers, the two linear current-voltage regimes can dominate the whole voltage range, and the intermediate Mott-Gurney regime can shrink or disappear. In this case, which will especially occur for thicknesses and injection barriers typical of single-carrier devices used to probe organic semiconductors, a meaningful analysis using the Mott-Gurney law will become unachievable, because a square-law fit can no longer be achieved, resulting in the mobility being substantially underestimated. General criteria for when to expect deviations from the Mott-Gurney law when used for analysis of intrinsic semiconductors are discussed.

Essential Components of a Perimeter Air Monitoring Plan and Worker Protection Program at Sites Involving the Excavation of Naturally Occurring Asbestos (NOA) in California

NASA Astrophysics Data System (ADS)

Zdeb, T. F.

2012-12-01

Preparing a Perimeter Air Monitoring Plan that provides the essential information and methods of evaluation needed to assure that the health of the surrounding community is adequately protected and adapting currently existing Cal/OSHA regulations to be relevant to the protection of workers at sites involving the excavation of Naturally Occurring Asbestos (NOA) is oftentimes challenging in California. Current guidelines regarding what constitutes an effective air monitoring program are often lacking in details regarding what should be sampled and analyzed to characterize a site and what evaluation techniques should be applied to process the results of monitoring, and the current Cal/OSHA asbestos related regulations regarding worker protection are for the most part largely pertinent to the abatement of asbestos in buildings. An overview of the essential components of an effective Baseline and Perimeter Air Monitoring Plan will be presented that includes a brief discussion of the various asbestos types and fiber sizes that may need to be considered, possible approachs for evaluating temporal and spatial variability, review of selected site boundary target concentrations, and consideration of the potential for airborne dust and soil containing asbestos (and other contaminants) to migrate and accumulate offsite eventually contributing to "background creep" --the incremental increase of overall airborne asbestos concentrations in the areas surrounding the site due to the re-entrainment of asbestos from the settled dust and/or transported soil. In addition to the above, the current Cal/OSHA asbestos regulations related to worker protection will be briefly discussed with respect to their relevancy at NOA sites with an overview of the adaptations to the regulations that were developed as a result of some fairly lengthy discussions with representatives of Cal/OSHA. These adaptations include, among other things, defining how regulated areas (asbestos concentrations over 1%) and "provisionally regulated" areas (less than 1%) are established and treated, what variables need to be considered when attempting to complete a personal exposure assessment, Cal/OSHA Permissible Exposure Limits (PELs) versus site specific permissible exposure limits, allowable work practices, and the qualifications of personnel performing the sampling and analyses of data.

Molecular Imaging of Pancreatic Cancer with Antibodies

PubMed Central

2015-01-01

Development of novel imaging probes for cancer diagnostics remains critical for early detection of disease, yet most imaging agents are hindered by suboptimal tumor accumulation. To overcome these limitations, researchers have adapted antibodies for imaging purposes. As cancerous malignancies express atypical patterns of cell surface proteins in comparison to noncancerous tissues, novel antibody-based imaging agents can be constructed to target individual cancer cells or surrounding vasculature. Using molecular imaging techniques, these agents may be utilized for detection of malignancies and monitoring of therapeutic response. Currently, there are several imaging modalities commonly employed for molecular imaging. These imaging modalities include positron emission tomography (PET), single-photon emission computed tomography (SPECT), magnetic resonance (MR) imaging, optical imaging (fluorescence and bioluminescence), and photoacoustic (PA) imaging. While antibody-based imaging agents may be employed for a broad range of diseases, this review focuses on the molecular imaging of pancreatic cancer, as there are limited resources for imaging and treatment of pancreatic malignancies. Additionally, pancreatic cancer remains the most lethal cancer with an overall 5-year survival rate of approximately 7%, despite significant advances in the imaging and treatment of many other cancers. In this review, we discuss recent advances in molecular imaging of pancreatic cancer using antibody-based imaging agents. This task is accomplished by summarizing the current progress in each type of molecular imaging modality described above. Also, several considerations for designing and synthesizing novel antibody-based imaging agents are discussed. Lastly, the future directions of antibody-based imaging agents are discussed, emphasizing the potential applications for personalized medicine. PMID:26620581

Service Modeling for Service Engineering

NASA Astrophysics Data System (ADS)

Shimomura, Yoshiki; Tomiyama, Tetsuo

Intensification of service and knowledge contents within product life cycles is considered crucial for dematerialization, in particular, to design optimal product-service systems from the viewpoint of environmentally conscious design and manufacturing in advanced post industrial societies. In addition to the environmental limitations, we are facing social limitations which include limitations of markets to accept increasing numbers of mass-produced artifacts and such environmental and social limitations are restraining economic growth. To attack and remove these problems, we need to reconsider the current mass production paradigm and to make products have more added values largely from knowledge and service contents to compensate volume reduction under the concept of dematerialization. Namely, dematerialization of products needs to enrich service contents. However, service was mainly discussed within marketing and has been mostly neglected within traditional engineering. Therefore, we need new engineering methods to look at services, rather than just functions, called "Service Engineering." To establish service engineering, this paper proposes a modeling technique of service.

Soil Health Assessment Approaches and the Cornell Framework

NASA Astrophysics Data System (ADS)

van Es, Harold

2016-04-01

Soil health constraints beyond nutrient limitations and excesses currently limit agroecosystem productivity and sustainability, resilience to drought and extreme rainfall, and progress in soil and water conservation. With mounting pressure to produce food, feed, fiber, and even fuel for an increasing population, the concept of soil health is gaining national and international attention. Multiple regional, national, and global efforts are now leveraging that work to reach new stakeholder audiences, so that soil health management is expanding into mainstream agriculture. Each grower is generally faced with a unique situation in the choice of management options to address soil health constraints and each system affords its own set of opportunities or limitations to soil management. A more comprehensive understanding of soil health status can better guide farmers' management decisions. Until recently, there has not been a formalized decision making process for implementing a soil health management system that alleviates field-specific constrains identified through standard measurements and then maintains improved soil health. This presentation will discuss current US-based efforts related to soil health assessment, including efforts to build national consensus on appropriate methods for simple (inexpensive) and comprehensive tests. This includes the Cornell Soil Health Management Planning and Implementation Framework. The most relevant components of the framework are 1) measurement of indicators that represent critical soil processes, 2) scoring of measured values that allows for interpretation, and 3) linkage of identified constraints with management practices. Land managers can monitor changes over time through further assessment, and adapt management practices to achieve chosen goals. We will discuss the full tests and approaches for simplification.

Next-generation mid-infrared sources

NASA Astrophysics Data System (ADS)

Jung, D.; Bank, S.; Lee, M. L.; Wasserman, D.

2017-12-01

The mid-infrared (mid-IR) is a wavelength range with a variety of technologically vital applications in molecular sensing, security and defense, energy conservation, and potentially in free-space communication. The recent development and rapid commercialization of new coherent mid-infrared sources have spurred significant interest in the development of mid-infrared optical systems for the above applications. However, optical systems designers still do not have the extensive optical infrastructure available to them that exists at shorter wavelengths (for instance, in the visible and near-IR/telecom wavelengths). Even in the field of optoelectronic sources, which has largely driven the growing interest in the mid-infrared, the inherent limitations of state-of-the-art sources and the gaps in spectral coverage offer opportunities for the development of new classes of lasers, light emitting diodes and emitters for a range of potential applications. In this topical review, we will first present an overview of the current state-of-the-art mid-IR sources, in particular thermal emitters, which have long been utilized, and the relatively new quantum- and interband-cascade lasers, as well as the applications served by these sources. Subsequently, we will discuss potential mid-infrared applications and wavelength ranges which are poorly served by the current stable of mid-IR sources, with an emphasis on understanding the fundamental limitations of the current source technology. The bulk of the manuscript will then explore both past and recent developments in mid-infrared source technology, including narrow bandgap quantum well lasers, type-I and type-II quantum dot materials, type-II superlattices, highly mismatched alloys, lead-salts and transition-metal-doped II-VI materials. We will discuss both the advantages and limitations of each of the above material systems, as well as the potential new applications which they might serve. All in all, this topical review does not aim to provide a survey of the current state of the art for mid-IR sources, but instead looks primarily to provide a picture of potential next-generation optical and optoelectronic materials systems for mid-IR light generation.

Robotic posterior retroperitoneal adrenalectomy.

PubMed

Okoh, Alexis Kofi; Yigitbas, Hakan; Berber, Eren

2015-09-01

Since its initial description by Mercan et al. laparoscopic posterior retroperitoneal (PR) adrenalectomy has served as an alternaltive to the transabdominal (TL) approach for the treatment of adrenal pathologies. Robotic adrenal surgery has been reported to improve surgeon ergonomics and facilitate dissection. In patients with bilateral adrenal masses, PR adrenalectomy may be the approach of choice. We herein describe the technique, discuss its limitations and present a critical review of the current literature. © 2015 Wiley Periodicals, Inc.

Electro-optical characterization of GaAs solar cells

NASA Technical Reports Server (NTRS)

Olsen, Larry C.; Dunham, Glen; Addis, F. W.; Huber, Dan; Daling, Dave

1987-01-01

The electro-optical characterization of gallium arsenide p/n solar cells is discussed. The objective is to identify and understand basic mechanisms which limit the performance of high efficiency gallium arsenide solar cells. The approach involves conducting photoresponse and temperature dependent current-voltage measurements, and interpretation of the data in terms of theory to determine key device parameters. Depth concentration profiles are also utilized in formulating a model to explain device performance.

4800 B/S speech compression techniques for mobile satellite systems

NASA Technical Reports Server (NTRS)

Townes, S. A.; Barnwell, T. P., III; Rose, R. C.; Gersho, A.; Davidson, G.

1986-01-01

This paper will discuss three 4800 bps digital speech compression techniques currently being investigated for application in the mobile satellite service. These three techniques, vector adaptive predictive coding, vector excitation coding, and the self excited vocoder, are the most promising among a number of techniques being developed to possibly provide near-toll-quality speech compression while still keeping the bit-rate low enough for a power and bandwidth limited satellite service.

The mercedes-benz approach to γ-ray astronomy

NASA Astrophysics Data System (ADS)

Akerlof, Carl W.

1988-02-01

The sensitivity requirements for ground-based γ-ray astronomy are reviewed in the light of the most reliable estimates of stellar fluxes above 100 GeV. Current data strongly favor the construction of detectors with the lowest energy thresholds. Since improvements in angular resolution are limited by shower fluctuations, better methods of rejecting hadronic showers must be found to reliably observe the known astrophysical sources. Several possible methods for reducing this hadronic background are discussed.

Estimating Logistics Support of Reusable Launch Vehicles During Conceptual Design

NASA Technical Reports Server (NTRS)

Morris, W. D.; White, N. H.; Davies, W. T.; Ebeling, C. E.

1997-01-01

Methods exist to define the logistics support requirements for new aircraft concepts but are not directly applicable to new launch vehicle concepts. In order to define the support requirements and to discriminate among new technologies and processing choices for these systems, NASA Langley Research Center (LaRC) is developing new analysis methods. This paper describes several methods under development, gives their current status, and discusses the benefits and limitations associated with their use.

X-ray line polarization spectroscopy of Li-like satellite line spectra

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

Sherrill, Manolo Edgar; Abdallah, Joseph; Zhang, Honglin

2008-01-01

We apply the magnetic-sublevel atomic kinetics model POLAR to the calculation of polarization properties of satellite lines in Li-like Si driven by subpicosecond-duration laser pulses. We identify spectral lines whose polarization can serve as a marker of plasma anisotropy due to anisotropy in the electron distribution function. We also discuss the utility and limitations of ur current theoretical approach and point out possible future improvements and directions.

The Federal Aviation Administration Plan for Research, Engineering and Development. Volume 2. Project Descriptions

DTIC Science & Technology

1989-01-01

managerial areas , including: management and control of the operational requirements of the NAS F& E Plan; preparation, management, and control of the annual... areas (capacity, safety, security, and efficiency), highlights of key programs, and a discussion of the relationships of the RE&D Plan to the NAS F& E ...release of SUA , such as restricted airspace and military operations areas , are currently limited by several factors, including manual interagency

Simultaneous Dual Species Matter Wave Interferometry

NASA Astrophysics Data System (ADS)

Schlippert, Dennis; Albers, Henning; Richardson, Logan; Meiners, Christian; Hartwig, Jonas; Ertmer, Wolfgang; Rasel, Ernst

2014-05-01

We report on the first realization of a simultaneous 39K-87Rb-dual species matter wave interferometer measuring gravitational acceleration with the aim to test Einstein's Equivalence Principle (EEP). Compared to classical tests such as torsion pendulum experiments and Lunar Laser Ranging, chemical elements suitable for performing matter wave interferometry can provide complementary information. We show the performance of our apparatus and discuss current limitations and future improvements towards highly sensitive matter wave tests of EEP.

Dual-energy contrast-enhanced spectral mammography (CESM).

PubMed

Daniaux, Martin; De Zordo, Tobias; Santner, Wolfram; Amort, Birgit; Koppelstätter, Florian; Jaschke, Werner; Dromain, Clarisse; Oberaigner, Willi; Hubalek, Michael; Marth, Christian

2015-10-01

Dual-energy contrast-enhanced mammography is one of the latest developments in breast care. Imaging with contrast agents in breast cancer was already known from previous magnetic resonance imaging and computed tomography studies. However, high costs, limited availability-or high radiation dose-led to the development of contrast-enhanced spectral mammography (CESM). We reviewed the current literature, present our experience, discuss the advantages and drawbacks of CESM and look at the future of this innovative technique.

The Case for Licensure of Applied Behavior Analysts

PubMed Central

Dorsey, Michael F; Weinberg, Michael; Zane, Thomas; Guidi, Megan M

2009-01-01

The evolution of the field of applied behavior analysis to a practice-oriented profession has created the need to ensure that the consumers of these services are adequately protected. We review the limitations of the current board certification process and present a rationale for the establishment of licensing standards for applied behavior analysts on a state-by-state basis. Recommendations for securing the passage of a licensure bill also are discussed. PMID:22477697

Recent Progress in Electrical Insulation Techniques for HTS Power Apparatus

NASA Astrophysics Data System (ADS)

Hayakawa, Naoki; Kojima, Hiroki; Hanai, Masahiro; Okubo, Hitoshi

This paper describes the electrical insulation techniques at cryogenic temperatures, i.e. Cryodielectrics, for HTS power apparatus, e.g. HTS power transmission cables, transformers, fault current limiters and SMES. Breakdown and partial discharge characteristics are discussed for different electrical insulation configurations of LN2, sub-cooled LN2, solid, vacuum and their composite insulation systems. Dynamic and static insulation performances with and without taking account of quench in HTS materials are also introduced.

A new approach to equipment testing

NASA Technical Reports Server (NTRS)

Hardwick, C. J.; Dunkley, V. P.; Burrows, B. J. C.; Darney, I.

1991-01-01

Considerable controversy has arisen during the recent discussions over a new version of the RTCA DO160C/ED 14C Section 22 document at the European Committee for Aviation Electronics. Section 22 is concerned with lightning waveform tests to equipment. Investigations of some of these controversies with circuit analysis and measurements indicate the impedance characteristics required of the transient generators and the possibility of testing to a voltage limit even for current waveforms.

A new approach to equipment testing

NASA Astrophysics Data System (ADS)

Hardwick, C. J.; Dunkley, V. P.; Burrows, B. J. C.; Darney, I.

1991-08-01

Considerable controversy has arisen during the recent discussions over a new version of the RTCA DO160C/ED 14C Section 22 document at the European Committee for Aviation Electronics. Section 22 is concerned with lightning waveform tests to equipment. Investigations of some of these controversies with circuit analysis and measurements indicate the impedance characteristics required of the transient generators and the possibility of testing to a voltage limit even for current waveforms.

1998 Gordon Research Conference on Gravitational Effects on Living Systems

NASA Technical Reports Server (NTRS)

Evans, Michael L.

1998-01-01

The Gordon Research Conference (GRC) on GRAVITATIONAL EFFECTS ON LIVING SYSTEMS was held at COLBY SAYWER 2 from 7/12/98 thru 7/17/98. The Conference was well-attended with 94 participants. The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, both U.S. and foreign scientists, senior researchers, young investigators, and students. In designing the formal speakers program, emphasis was placed on current unpublished research and discussion of the future target areas in this field. There was a conscious effort to stimulate lively discussion about the key issues in the field today. Time for formal presentations was limited in the interest of group discussions. In order that more scientists could communicate their most recent results, poster presentation time was scheduled. A copy of the formal schedule and speaker program and the poster program is included. In addition to these formal interactions, "free time" was scheduled to allow informal discussions. Such discussions are fostering new collaborations and joint efforts in the field.