Redundancy and Reduction: Speakers Manage Syntactic Information Density

ERIC Educational Resources Information Center

Jaeger, T. Florian

2010-01-01

A principle of efficient language production based on information theoretic considerations is proposed: Uniform Information Density predicts that language production is affected by a preference to distribute information uniformly across the linguistic signal. This prediction is tested against data from syntactic reduction. A single multilevel…

The quantitative modelling of human spatial habitability

NASA Technical Reports Server (NTRS)

Wise, James A.

1988-01-01

A theoretical model for evaluating human spatial habitability (HuSH) in the proposed U.S. Space Station is developed. Optimizing the fitness of the space station environment for human occupancy will help reduce environmental stress due to long-term isolation and confinement in its small habitable volume. The development of tools that operationalize the behavioral bases of spatial volume for visual kinesthetic, and social logic considerations is suggested. This report further calls for systematic scientific investigations of how much real and how much perceived volume people need in order to function normally and with minimal stress in space-based settings. The theoretical model presented in this report can be applied to any size or shape interior, at any scale of consideration, for the Space Station as a whole to an individual enclosure or work station. Using as a point of departure the Isovist model developed by Dr. Michael Benedikt of the U. of Texas, the report suggests that spatial habitability can become as amenable to careful assessment as engineering and life support concerns.

The Vulnerable Age: A Serendipitous Finding

ERIC Educational Resources Information Center

Inbar, Michael; Adler, Chaim

1976-01-01

Six to 11 year old children may be generally more vulnerable to crises in their environment than their younger or older siblings. Based upon a cross cultural study of Moroccan and Rumanian immigrants to Israel, the authors suggest some theoretical considerations and note some practical implications. (Author/DB)

Mathematics, Modelling and Students in Transition

ERIC Educational Resources Information Center

Wake, Geoff

2016-01-01

This article is based on data from two major research projects that investigated students involved in mathematically demanding courses during their transition through college and into university. It explores the nature of modelling as a mathematical practice in this important transition phase for students. Theoretical considerations are informed…

Studying the Leaders of Classical Antiquity.

ERIC Educational Resources Information Center

Moritz, Helen E.

This paper describes a graduate seminar for educational administrators, using works of ancient Greek and Roman literature as bases for the consideration of organization and leadership problems identified in theoretical literature. The seminar was team taught by professors from the Departments of Educational Administration and Classics at the…

Big Ideas in Primary Mathematics: Issues and Directions

ERIC Educational Resources Information Center

Askew, Mike

2013-01-01

This article is located within the literature arguing for attention to Big Ideas in teaching and learning mathematics for understanding. The focus is on surveying the literature of Big Ideas and clarifying what might constitute Big Ideas in the primary Mathematics Curriculum based on both theoretical and pragmatic considerations. This is…

Strategic Renewal and Development Implications of Organisational Effectiveness Research in Higher Education in Australia.

ERIC Educational Resources Information Center

Lysons, Art

1999-01-01

Suggests that organizational effectiveness research has made considerable progress in empirically deriving a systematic framework of theoretical and practical utility in Australian higher education. Offers a taxonomy based on the competing values framework and discusses use of inter-organizational comparisons and profiles for diagnosis in…

Social Cognitive Theory Recommendations for Improving Modeling in Adolescent Substance Abuse Prevention Programs.

ERIC Educational Resources Information Center

Cleaveland, Bonnie L.

1994-01-01

Current state-of-the-art substance abuse prevention programs are mostly social cognitive theory based. However, there are few publications which review specifically how modeling is applied to adolescent substance abuse prevention programs. This article reviews theoretical considerations for implementing modeling for this purpose. (Author/LKS)

Research Considerations and Theoretical Application for Best Practices in Higher Education: Latina/os Achieving Success

ERIC Educational Resources Information Center

Castellanos, Jeanett; Gloria, Alberta M.

2007-01-01

This scholarly article addresses the Latina/o undergraduate experiences proposing a (re)definition of educational success. Discussing strength-based practices of "familia", mentorship, cultural congruity, and professional development from a psychosociocultural (PSC) approach, the article presents practical recommendations and directions for…

Research Supervision: The Research Management Matrix

ERIC Educational Resources Information Center

Maxwell, T. W.; Smyth, Robyn

2010-01-01

We briefly make a case for re-conceptualising research project supervision/advising as the consideration of three inter-related areas: the learning and teaching process; developing the student; and producing the research project/outcome as a social practice. We use this as our theoretical base for an heuristic tool, "the research management…

Snarks, Quarks and Cognates: An Elusive Fundamental Particle in Reading Comprehension.

ERIC Educational Resources Information Center

Holmes, John L.

1986-01-01

Discusses recognition of cognates used in teaching materials prepared by the English for Specific Purposes Project for academic courses. Presents suggestions based on theoretical considerations of cognate recognition. Examines, by way of protocol studies, how foreign students of English make use of cognate recognition. Suggests that strategies for…

GaSbBi/GaSb quantum-well and wire laser diodes

NASA Astrophysics Data System (ADS)

Ridene, Said

2018-06-01

In this work, we present detailed theoretical studies of the optical gain spectra and the emission wavelength of GaSb1-xBix/GaSb and traditional GaAs1-xBix/GaAs dilute-bismide quantum wells and wires (QWs, QWRs) focusing on comparison between their performances. It is found that the optical gain and the emission wavelength of the GaSb-based QW and QWRs lasers would be considerably greater than that of the GaAs-based QW lasers and QWRs for the same QW-, QWR-width, Bi-content and carrier density. The theoretical results were found to be in good agreement with available experimental data, especially for the emission wavelength given by GaSb-based QW laser diodes.

Moiré deflectometry-based position detection for optical tweezers.

PubMed

Khorshad, Ali Akbar; Reihani, S Nader S; Tavassoly, Mohammad Taghi

2017-09-01

Optical tweezers have proven to be indispensable tools for pico-Newton range force spectroscopy. A quadrant photodiode (QPD) positioned at the back focal plane of an optical tweezers' condenser is commonly used for locating the trapped object. In this Letter, for the first time, to the best of our knowledge, we introduce a moiré pattern-based detection method for optical tweezers. We show, both theoretically and experimentally, that this detection method could provide considerably better position sensitivity compared to the commonly used detection systems. For instance, position sensitivity for a trapped 2.17 μm polystyrene bead is shown to be 71% better than the commonly used QPD-based detection method. Our theoretical and experimental results are in good agreement.

Toward a Physical Characterization of Raindrop Collision Outcome Regimes

NASA Technical Reports Server (NTRS)

Testik, F. Y.; Barros, Ana P.; Bilven, Francis L.

2011-01-01

A comprehensive raindrop collision outcome regime diagram that delineates the physical conditions associated with the outcome regimes (i.e., bounce, coalescence, and different breakup types) of binary raindrop collisions is proposed. The proposed diagram builds on a theoretical regime diagram defined in the phase space of collision Weber numbers We and the drop diameter ratio p by including critical angle of impact considerations. In this study, the theoretical regime diagram is first evaluated against a comprehensive dataset for drop collision experiments representative of raindrop collisions in nature. Subsequently, the theoretical regime diagram is modified to explicitly describe the dominant regimes of raindrop interactions in (We, p) by delineating the physical conditions necessary for the occurrence of distinct types of collision-induced breakup (neck/filament, sheet, disk, and crown breakups) based on critical angle of impact consideration. Crown breakup is a subtype of disk breakup for lower collision kinetic energy that presents distinctive morphology. Finally, the experimental results are analyzed in the context of the comprehensive collision regime diagram, and conditional probabilities that can be used in the parameterization of breakup kernels in stochastic models of raindrop dynamics are provided.

Standing on the shoulders of giants: Star and planet formation in 2010-2020 - The Kenneth Greisen Lecture

NASA Astrophysics Data System (ADS)

McCaughrean, Mark

2008-04-01

Despite centuries of theoretical hypotheses on the origin of our own Sun and its planets, it is only in the past thirty years that we have begun to develop an empirical, observational picture of how stars and planets are forming today throughout our Galaxy and beyond. Driven largely by the advent of infrared and millimetre astronomy in the 1970s and 1980s, progress in the field has accelerated considerably in the past 10 years through the combination of powerful ground- and space-telescopes covering the X-ray, optical, infrared and millimetre, in addition to considerable improvements in theoretical simulations. In this talk, I shall present an overview of recent observational and theoretical work on the birth and early evolution of stars, brown dwarfs, circumstellar disks, jets, outflows, and planetary systems. In doing so, I shall also identify key problems which future facilities, including the next generation of extremely large ground-based telescopes and the NASA/ESA/CSA James Webb Space Telescope, will play vital roles in helping to unravel over the coming decade.

Some Considerations Necessary for a Viable Theory of Human Memory.

ERIC Educational Resources Information Center

Sietsema, Douglas J.

Empirical research is reviewed in the area of cognitive psychology pertaining to models of human memory. Research evidence and theoretical considerations are combined to develop guidelines for future theory development related to the human memory. The following theoretical constructs and variables are discussed: (1) storage versus process…

Photonics and spectroscopy in nanojunctions: a theoretical insight

DOE PAGES

Galperin, Michael

2017-04-11

The progress of experimental techniques at the nanoscale in the last decade made optical measurements in current-carrying nanojunctions a reality, thus indicating the emergence of a new field of research coined optoelectronics. Optical spectroscopy of open nonequilibrium systems is a natural meeting point for (at least) two research areas: nonlinear optical spectroscopy and quantum transport, each with its own theoretical toolbox. We review recent progress in the field comparing theoretical treatments of optical response in nanojunctions as is accepted in nonlinear spectroscopy and quantum transport communities. A unified theoretical description of spectroscopy in nanojunctions is presented. Here, we argue thatmore » theoretical approaches of the quantum transport community (and in particular, the Green function based considerations) yield a convenient tool for optoelectronics when the radiation field is treated classically, and that differences between the toolboxes may become critical when studying the quantum radiation field in junctions.« less

Explaining the use of text-based communication media: an examination of three theories of media use.

PubMed

Park, Namkee; Chung, Jae Eun; Lee, Seungyoon

2012-07-01

The present study examined the factors associated with individuals' use of three different text-based communication media: e-mail, cell-phone texting, and Facebook Wall postings. Three theoretical perspectives, including media richness theory, uses and gratifications, and perceived network effects, were examined. Using data from a survey of college students (N=280), the study found that the theoretical constructs from these theories play different roles when applied to different technologies. The results suggest that a simultaneous consideration of technological attributes, users' motivations, and social circumstances in which users select and use the technology is useful for fully understanding the dynamics of the selection and the use of a given technology.

The Experience of Transformation in Parents of Children with Disabilities: Theoretical Considerations

ERIC Educational Resources Information Center

Scorgie, Kate; Wilgosh, Lorraine; Sobsey, Dick

2004-01-01

Many parents assert that, despite the considerable and sustained stresses involved in parenting a child with a disability, their experiences have been personally transformative. Increasingly, researchers are advocating for a theoretical understanding of family life management following the diagnosis of disability in a child, with an emphasis on…

Recommended Values of Meteorological Factors to Be Considered in the Design of Aircraft Ice-Prevention Equipment

NASA Technical Reports Server (NTRS)

Jones, Alun R; Lewis, William

1949-01-01

Meteorological conditions conducive to aircraft icing are arranged in four classifications: three are associated with cloud structure and the fourth with freezing rain. The range of possible meteorological factors for each classification is discussed and specific values recommended for consideration in the design of ice-prevention equipment for aircraft are selected and tabulated. The values selected are based upon a study of the available observational data and theoretical considerations where observations are lacking. Recommendations for future research in the field are presented.

Perceptions of Problem Behavior in Adolescents' Families: Perceiver, Target, and Family Effects

ERIC Educational Resources Information Center

Manders, Willeke A.; Janssens, Jan M. A. M.; Cook, William L.; Oud, Johan H. L.; De Bruyn, Eric E. J.; Scholte, Ron H. J.

2009-01-01

Considerable research has focused on the reliability and validity of informant reports of family behavior, especially maternal reports of adolescent problem behavior. None of these studies, however, has based their orientation on a theoretical model of interpersonal perception. In this study we used the social relations model (SRM) to examine…

Skilled Voices?: Reflections on Political Participation and Education in Austria. OECD Education Working Papers, No. 11

ERIC Educational Resources Information Center

Walter, Florian; Rosenberger, Sieglinde

2007-01-01

This study, part of OECD/CERI's project on Measuring the Social Outcomes of Learning, investigates the relationship between educational attainment and political participation in Austria. First, a model based on various theoretical considerations is introduced. This incorporates direct educational effects as well as indirect effects that occur…

Can You Tell the Density of the Watermelon from This Photograph?

ERIC Educational Resources Information Center

Foong, See Kit; Lim, Chim Chai

2010-01-01

Based on a photograph, the density of a watermelon floating in a pail of water is estimated with different levels of simplification--with and without consideration of refraction and three-dimensional effects. The watermelon was approximated as a sphere. The results of the theoretical estimations were verified experimentally. (Contains 6 figures.)

Evaluating Instrument Quality in Science Education: Rasch-Based Analyses of a Nature of Science Test

ERIC Educational Resources Information Center

Neumann, Irene; Neumann, Knut; Nehm, Ross

2011-01-01

Given the central importance of the Nature of Science (NOS) and Scientific Inquiry (SI) in national and international science standards and science learning, empirical support for the theoretical delineation of these constructs is of considerable significance. Furthermore, tests of the effects of varying magnitudes of NOS knowledge on…

Music Education and Deliberative Democracy

ERIC Educational Resources Information Center

Bladh, Stephan; Heimonen, Marja

2007-01-01

In this paper, the authors discuss the influence of democracy and law on music education in Sweden and Finland, and the potential for music education as training in democracy. The latter consideration can be instructive regardless of the nation, or its laws and paradigms of music education. The theoretical background is based on Jurgen Habermas'…

Supporting Evidence-Based Policy on Biodiversity and Ecosystem Services: Recommendations for Effective Policy Briefs

ERIC Educational Resources Information Center

Balian, Estelle V.; Drius, Liza; Eggermont, Hilde; Livoreil, Barbara; Vandewalle, Marie; Vandewoestjine, Sofie; Wittmer, Heidi; Young, Juliette

2016-01-01

Knowledge brokerage on biodiversity and ecosystem services can apply communication tools such as policy briefs to facilitate the dialogue between scientists and policymakers. There is currently considerable debate on how to go beyond the linear communication model, outdated in theoretical debate but still often implicitly leading interaction with…

The Ethical Behavior of Counselors: New Directions in Ethical Behavior Research.

ERIC Educational Resources Information Center

Paradise, Louis V.

The ethical behavior of counselors is an issue of current importance to those in the profession. This paper briefly examines the literature in this area. While considerable descriptive research on ethical behavior exists, the conspicuous absence of any experimental methodologies and theoretically-based investigations were noted. The need for new…

Market Movements and the Dispossessed: Race, Identity, and Subaltern Agency among Black Women Voucher Advocates

ERIC Educational Resources Information Center

Pedroni, Thomas C.

2005-01-01

Critical educational researchers in the United States and elsewhere are missing something essential in their inattention to considerable support among Black urban women for market-based educational reforms, including vouchers. While the educational left has engaged in important empirical and theoretical work demonstrating the particularly negative…

Studying the Degree of Creativity of Preschool Children Drawings

ERIC Educational Resources Information Center

Dulama, Maria Eliza; Alexandru, Diana; Vanea, Cornelia

2010-01-01

Our purpose is to offer children tasks so they can make drawings as diverse and different from each other whilst trying to avoid imitation. Achieving this goal involves the increase of children's creativity. The paper is theoretically based on the consideration of creativity as the ability to create "something new, original, and in accordance…

Nonoptical definition of applanation surface.

PubMed

Draeger, J; Rumberger, E; Hechler, B; Wirt, H; Levedag, S; Rudolph, G; Ludwig, B; Klemm, M

1987-01-01

Based on the Imbert-Fick law and the theoretical considerations of Goldmann, new applanation tonometers were designed, still using an applanation diameter of 3.06 mm to avoid a new biometric calibration. Three different electronic recording devices were used for the area assessment. An optical, a capacitance and a digital line sensor were tested in first calibration experiments.

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

Bogdanov, Yu. I., E-mail: bogdanov-yurii@inbox.ru; Avosopyants, G. V.; Belinskii, L. V.

We describe a new method for reconstructing the quantum state of the electromagnetic field from the results of mutually complementary optical quadrature measurements. This method is based on the root approach and displaces squeezed Fock states are used as the basis. Theoretical analysis and numerical experiments demonstrate the considerable advantage of the developed tools over those described in the literature.

Fantasy Activity and the Televiewing Event: Considerations for an Information Processing Construct of Involvement.

ERIC Educational Resources Information Center

Lindlof, Thomas R.

The similarities between television viewing and fantasy activity (daydreaming, reverie, mind-wandering, internal dialogue) more than warrant the building of a theoretical construct, especially in the context of recent empirical research on television viewing consequences. A construct of the television viewing process, based on cognitive theories…

Longitudinal Examination of Optimism, Personal Self-Efficacy and Student Well-Being: A Path Analysis

ERIC Educational Resources Information Center

Phan, Huy P.

2016-01-01

The present longitudinal study, based on existing theoretical tenets, explored a conceptual model that depicted four major orientations: optimism, self-efficacy, and academic well-being. An important question for consideration, in this case, involved the testing of different untested trajectories that could explain and predict individuals'…

Corrections on the Thermometer Reading in an Air Stream

NASA Technical Reports Server (NTRS)

Van Der Maas, H J; Wynia, S

1940-01-01

A method is described for checking a correction formula, based partly on theoretical considerations, for adiabatic compression and friction in flight tests and determining the value of the constant. It is necessary to apply a threefold correction to each thermometer reading. They are a correction for adiabatic compression, friction and for time lag.

Packaging consideration of two-dimensional polymer-based photonic crystals for laser beam steering

NASA Astrophysics Data System (ADS)

Dou, Xinyuan; Chen, Xiaonan; Chen, Maggie Yihong; Wang, Alan Xiaolong; Jiang, Wei; Chen, Ray T.

2009-02-01

In this paper, we report the theoretical study of polymer-based photonic crystals for laser beam steering which is based on the superprism effect as well as the experiment fabrication of the two dimensional photonic crystals for the laser beam steering. Superprism effect, the principle for beam steering, was separately studied in details through EFC (Equifrequency Contour) analysis. Polymer based photonic crystals were fabricated through double exposure holographic interference method using SU8-2007. The experiment results were also reported.

A constraint on antigravity of antimatter from precision spectroscopy of simple atoms

NASA Astrophysics Data System (ADS)

Karshenboim, S. G.

2009-10-01

Consideration of antigravity for antiparticles is an attractive target for various experimental projects. There are a number of theoretical arguments against it but it is not quite clear what kind of experimental data and theoretical suggestions are involved. In this paper we present straightforward arguments against a possibility of antigravity based on a few simple theoretical suggestions and some experimental data. The data are: astrophysical data on rotation of the Solar System in respect to the center of our galaxy and precision spectroscopy data on hydrogen and positronium. The theoretical suggestions for the case of absence of the gravitational field are: equality of electron and positron mass and equality of proton and positron charge. We also assume that QED is correct at the level of accuracy where it is clearly confirmed experimentally.

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

Galperin, Michael

The progress of experimental techniques at the nanoscale in the last decade made optical measurements in current-carrying nanojunctions a reality, thus indicating the emergence of a new field of research coined optoelectronics. Optical spectroscopy of open nonequilibrium systems is a natural meeting point for (at least) two research areas: nonlinear optical spectroscopy and quantum transport, each with its own theoretical toolbox. We review recent progress in the field comparing theoretical treatments of optical response in nanojunctions as is accepted in nonlinear spectroscopy and quantum transport communities. A unified theoretical description of spectroscopy in nanojunctions is presented. Here, we argue thatmore » theoretical approaches of the quantum transport community (and in particular, the Green function based considerations) yield a convenient tool for optoelectronics when the radiation field is treated classically, and that differences between the toolboxes may become critical when studying the quantum radiation field in junctions.« less

[The transgenerational transmission of traumatic experiences of the Second World War over three generations--a psychoanalytical perspective].

PubMed

Silke, Wiegand-Grefe; Möller, Birgit

2012-01-01

The paper presents some reflections on the transgenerational transmission of traumatic experiences of war and in particular bombing during Second World War. These theoretical considerations are based on a case study (family interview) deriving from the research project "Kriegskindheit im Hamburger Feuersturm" additionally illustrated and complemented with impressions based on interviews with three generations in context of the project.

Patterns of informal reasoning in the context of socioscientific decision making

NASA Astrophysics Data System (ADS)

Sadler, Troy D.; Zeidler, Dana L.

2005-01-01

The purpose of this study is to contribute to a theoretical knowledge base through research by examining factors salient to science education reform and practice in the context of socioscientific issues. The study explores how individuals negotiate and resolve genetic engineering dilemmas. A qualitative approach was used to examine patterns of informal reasoning and the role of morality in these processes. Thirty college students participated individually in two semistructured interviews designed to explore their informal reasoning in response to six genetic engineering scenarios. Students demonstrated evidence of rationalistic, emotive, and intuitive forms of informal reasoning. Rationalistic informal reasoning described reason-based considerations; emotive informal reasoning described care-based considerations; and intuitive reasoning described considerations based on immediate reactions to the context of a scenario. Participants frequently relied on combinations of these reasoning patterns as they worked to resolve individual socioscientific scenarios. Most of the participants appreciated at least some of the moral implications of their decisions, and these considerations were typically interwoven within an overall pattern of informal reasoning. These results highlight the need to ensure that science classrooms are environments in which intuition and emotion in addition to reason are valued. Implications and recommendations for future research are discussed.

The lack of theoretical support for using person trade-offs in QALY-type models.

PubMed

Østerdal, Lars Peter

2009-10-01

Considerable support for the use of person trade-off methods to assess the quality-adjustment factor in quality-adjusted life years (QALY) models has been expressed in the literature. The WHO has occasionally used similar methods to assess the disability weights for calculation of disability-adjusted life years (DALYs). This paper discusses the theoretical support for the use of person trade-offs in QALY-type measurement of (changes in) population health. It argues that measures of this type based on such quality-adjustment factors almost always violate the Pareto principle, and so lack normative justification.

Circumstellar chemistry

NASA Technical Reports Server (NTRS)

Glassgold, Alfred E.; Huggins, Patrick J.

1987-01-01

The study of the outer envelopes of cool evolved stars has become an active area of research. The physical properties of CS envelopes are presented. Observations of many wavelengths bands are relevant. A summary of observations and a discussion of theoretical considerations concerning the chemistry are summarized. Recent theoretical considerations show that the thermal equilibrium model is of limited use for understanding the chemistry of the outer CS envelopes. The theoretical modeling of the chemistry of CS envelopes provides a quantitive test of chemical concepts which have a broader interest than the envelopes themselves.

Historical Experiments and Physics Teaching: adding considerations from a Bibliographic Review and the Cultural History of Science

NASA Astrophysics Data System (ADS)

Jardim, W. T.; Guerra, A.

2017-12-01

In this paper, a discussion about the purposes of historical experiments in science teaching found in the literature will be presented. As a starting point, we carried out a bibliographic review, on the websites of six relevant periodicals for the area of Science Teaching and, especially for Physics Teaching. The search was based, at first, on works published between the years 2001 and 2016, from terms like "historical experiments", "museums" and "experience". Thereon, due to the large number of publications found, a screening process was developed based on the analysis of titles, abstracts, keywords and, whether necessary, the whole text, aiming to identify which searches emphasize working with historical experiments in Physics teaching, from a theoretical perspective or based on manipulation of a replica of historical apparatus. The selected proposals were arranged in categories adapted from the work of Heering and Höttecke (2014) which allowed us to draw a parallel between the national and international publication that presented resembling scopes. Furthermore, the analysis of the results leads us to infer that, in general, extralab factors, inherent to science, when not neglected, are placed in a peripheral perspective. Thus, we draw theoretical considerations based on Historians of Science, which develop their researches based on the bias of the Cultural History of Science, seeking to add reflections to what has been developed about historical experiments in teaching up to now.

Characteristic Features of Innovation Project Management Aimed at University Human Resource Development

ERIC Educational Resources Information Center

Kalimullin, Aydar M.; Yungblud, Valery T.; Khodyreva, Elena A.

2016-01-01

The relevance of the studied issue is based on the need to develop theoretical approaches to project management at a higher educational institution taking into consideration the specifics of the subject area of the projects that ensure finding the "growth points" and addressing the long-term objectives of a university in the field of…

Organizing the Baby Boomer Construct: An Exploration of Marketing, Social Systems, and Culture

ERIC Educational Resources Information Center

Lipschultz, Jeremy H.; Hilt, Michael L.; Reilly, Hugh J.

2007-01-01

Baby boomer trends are applied in the development of a conceptual framework that offers a social systems and cultural model for future studies. While there has been considerable recent attention paid to baby boomers, the studies lack a coherent theoretical base that would allow for more advanced and continuing research. Aging baby boomers heading…

Sustaining Youth Participation in a Long-Term Tobacco Control Initiative: Consideration of a Social Justice Perspective

ERIC Educational Resources Information Center

Ross, Laurie

2011-01-01

This article presents an in-depth case study of the Healthy Options for Prevention and Education Coalition's Teens Tackle Tobacco initiative, a 3-year community-based participatory research (CBPR) project about the distribution of tobacco vendors and tobacco advertising in Worcester, Massachusetts. Using two theoretical frameworks, positive youth…

College Students' Attention Behaviors during Independent Study and Course Level Academic Performance

ERIC Educational Resources Information Center

Wagner, Linda G.

2012-01-01

Students in college make daily choices about how to use their independent study time, including choices about allocation of attention. Based on theoretical considerations and clinical studies, attention and the dividing of attention through multitasking is thought to have a relationship to performance levels. Research is only beginning to explore,…

Point source detection in infrared astronomical surveys

NASA Technical Reports Server (NTRS)

Pelzmann, R. F., Jr.

1977-01-01

Data processing techniques useful for infrared astronomy data analysis systems are reported. This investigation is restricted to consideration of data from space-based telescope systems operating as survey instruments. In this report the theoretical background for specific point-source detection schemes is completed, and the development of specific algorithms and software for the broad range of requirements is begun.

Some Simple Solutions to the Problem of Predicting Boundary-Layer Self-Induced Pressures

NASA Technical Reports Server (NTRS)

Bertram, Mitchel H.; Blackstock, Thomas A.

1961-01-01

Simplified theoretical approaches are shown, based on hypersonic similarity boundary-layer theory, which allow reasonably accurate estimates to be made of the surface pressures on plates on which viscous effects are important. The consideration of viscous effects includes the cases where curved surfaces, stream pressure gradients, and leadingedge bluntness are important factors.

Discussion of the Design and Implementation of the Lauder Content-Based Curriculum: Practical and Theoretical Considerations.

ERIC Educational Resources Information Center

Cowles, Maria Antonia

The dual-degree MBA/MA program of the University of Pennsylvania is described. The program is designed to provide future business leaders with superior international management education and prepare them to operate effectively and comfortably in the global economy through social and professional language skills and knowledge of diverse cultural…

A Study of Wind Turbine Comprehensive Operational Assessment Model Based on EM-PCA Algorithm

NASA Astrophysics Data System (ADS)

Zhou, Minqiang; Xu, Bin; Zhan, Yangyan; Ren, Danyuan; Liu, Dexing

2018-01-01

To assess wind turbine performance accurately and provide theoretical basis for wind farm management, a hybrid assessment model based on Entropy Method and Principle Component Analysis (EM-PCA) was established, which took most factors of operational performance into consideration and reach to a comprehensive result. To verify the model, six wind turbines were chosen as the research objects, the ranking obtained by the method proposed in the paper were 4#>6#>1#>5#>2#>3#, which are completely in conformity with the theoretical ranking, which indicates that the reliability and effectiveness of the EM-PCA method are high. The method could give guidance for processing unit state comparison among different units and launching wind farm operational assessment.

Atmospheric turbulence compensation in orbital angular momentum communications: Advances and perspectives

NASA Astrophysics Data System (ADS)

Li, Shuhui; Chen, Shi; Gao, Chunqing; Willner, Alan E.; Wang, Jian

2018-02-01

Orbital angular momentum (OAM)-carrying beams have recently generated considerable interest due to their potential use in communication systems to increase transmission capacity and spectral efficiency. For OAM-based free-space optical (FSO) links, a critical challenge is the atmospheric turbulence that will distort the helical wavefronts of OAM beams leading to the decrease of received power, introducing crosstalk between multiple channels, and impairing link performance. In this paper, we review recent advances in turbulence effects compensation techniques for OAM-based FSO communication links. First, basic concepts of atmospheric turbulence and theoretical model are introduced. Second, atmospheric turbulence effects on OAM beams are theoretically and experimentally investigated and discussed. Then, several typical turbulence compensation approaches, including both adaptive optics-based (optical domain) and signal processing-based (electrical domain) techniques, are presented. Finally, key challenges and perspectives of compensation of turbulence-distorted OAM links are discussed.

[A framework for evaluating ethical issues of public health initiatives: practical aspects and theoretical implications].

PubMed

Petrini, Carlo

2015-01-01

The "Framework for the Ethical Conduct of Public Health Initiatives", developed by Public Health Ontario, is a practical guide for assessing the ethical implications of evidence-generating public health initiatives, whether research or non-research activities, involving people, their biological materials or their personal information. The Framework is useful not only to those responsible for determining the ethical acceptability of an initiative, but also to investigators planning new public health initiatives. It is informed by a theoretical approach that draws on widely shared bioethical principles. Two considerations emerge from both the theoretical framework and its practical application: the line between practice and research is often blurred; public health ethics and biomedical research ethics are based on the same common heritage of values.

Development and Confirmatory Factory Analysis of the Achievement Task Value Scale for University Students

ERIC Educational Resources Information Center

Lou, Yu-Chiung; Lin, Hsiao-Fang; Lin, Chin-Wen

2013-01-01

The aims of the study were (a) to develop a scale to measure university students' task value and (b) to use confirmatory factor analytic techniques to investigate the construct validity of the scale. The questionnaire items were developed based on theoretical considerations and the final version contained 38 items divided into 4 subscales.…

Job Tasks and the Participation of Low-Skilled Employees in Employer-Provided Continuing Training in Germany

ERIC Educational Resources Information Center

Mohr, Sabine; Troltsch, Klaus; Gerhards, Christian

2016-01-01

This study analyses the participation of low-skilled employees in employer-provided training and examines the mechanisms that encourage the training participation of low-skilled employees. Building on theoretical considerations of human capital theory and the task-based approach, we seek to show that job tasks play an important role in explaining…

Theoretical and Empirical Underpinnings of the What Works Clearinghouse Attrition Standard for Randomized Controlled Trials

ERIC Educational Resources Information Center

Deke, John; Chiang, Hanley

2014-01-01

Meeting the What Works Clearinghouse (WWC) attrition standard (or one of the attrition standards based on the WWC standard) is now an important consideration for researchers conducting studies that could potentially be reviewed by the WWC (or other evidence reviews). Understanding the basis of this standard is valuable for anyone seeking to meet…

Taking the U.S. Patent Office Criteria Seriously: A Quantitative Three-Criterion Creativity Definition and Its Implications

ERIC Educational Resources Information Center

Simonton, Dean Keith

2012-01-01

Although creativity has recently attracted considerable theoretical and empirical research, researchers have yet to reach a consensus on how best to define the phenomenon. To help establish a consensus, a definition is proposed that is based on the three criteria used by the United States Patent Office to evaluate applications for patent…

Trauma-Focused Cognitive-Behavioral Therapy for Posttraumatic Stress Disorder in Three-Through Six Year-Old Children: A Randomized Clinical Trial

ERIC Educational Resources Information Center

Scheeringa, Michael S.; Weems, Carl F.; Cohen, Judith A.; Amaya-Jackson, Lisa; Guthrie, Donald

2011-01-01

Background: The evidence base for trauma-focused cognitive behavioral therapy (TF-CBT) to treat posttraumatic stress disorder (PTSD) in youth is compelling, but the number of controlled trials in very young children is few and limited to sexual abuse victims. These considerations plus theoretical limitations have led to doubts about the…

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

Dolen, James; Harris, Philip; Marzani, Simone

Here, we explore the scale-dependence and correlations of jet substructure observables to improve upon existing techniques in the identification of highly Lorentz-boosted objects. Modified observables are designed to remove correlations from existing theoretically well-understood observables, providing practical advantages for experimental measurements and searches for new phenomena. We study such observables in W jet tagging and provide recommendations for observables based on considerations beyond signal and background efficiencies.

Theory and applications of structured light single pixel imaging

NASA Astrophysics Data System (ADS)

Stokoe, Robert J.; Stockton, Patrick A.; Pezeshki, Ali; Bartels, Randy A.

2018-02-01

Many single-pixel imaging techniques have been developed in recent years. Though the methods of image acquisition vary considerably, the methods share unifying features that make general analysis possible. Furthermore, the methods developed thus far are based on intuitive processes that enable simple and physically-motivated reconstruction algorithms, however, this approach may not leverage the full potential of single-pixel imaging. We present a general theoretical framework of single-pixel imaging based on frame theory, which enables general, mathematically rigorous analysis. We apply our theoretical framework to existing single-pixel imaging techniques, as well as provide a foundation for developing more-advanced methods of image acquisition and reconstruction. The proposed frame theoretic framework for single-pixel imaging results in improved noise robustness, decrease in acquisition time, and can take advantage of special properties of the specimen under study. By building on this framework, new methods of imaging with a single element detector can be developed to realize the full potential associated with single-pixel imaging.

Theoretical study of the A prime 5Sigma(+)g and C double prime 5Pi u states of N2 - Implications for the N2 afterglow

NASA Technical Reports Server (NTRS)

Partridge, Harry; Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Schwenke, David W.

1988-01-01

Theoretical spectroscopic constants are reported for the A prime 5Sigma(+)g and C double prime 5Pi u states of N2 based on CASSCF/MRCI calculations using large ANO Gaussian basis sets. The calculated A prime Sigma(+)g potential differs qualitatively from previous calculations in that the inner well is significantly deeper (De = 3450/cm). This deeper well provides considerable support for the suggestion of Berkowitz et al. (1956) that A prime 5Sigma(+)g is the primary precursor state involved in the yellow Lewis-Rayleigh afterglow of N2.

Piezoelectric line moment actuator for active radiation control from light-weight structures

NASA Astrophysics Data System (ADS)

Jandak, Vojtech; Svec, Petr; Jiricek, Ondrej; Brothanek, Marek

2017-11-01

This article outlines the design of a piezoelectric line moment actuator used for active structural acoustic control. Actuators produce a dynamic bending moment that appears in the controlled structure resulting from the inertial forces when the attached piezoelectric stripe actuators start to oscillate. The article provides a detailed theoretical analysis necessary for the practical realization of these actuators, including considerations concerning their placement, a crucial factor in the overall system performance. Approximate formulas describing the dependency of the moment amplitude on the frequency and the required electric voltage are derived. Recommendations applicable for the system's design based on both theoretical and empirical results are provided.

Instrumentation for the detection and characterization of exoplanets.

PubMed

Pepe, Francesco; Ehrenreich, David; Meyer, Michael R

2014-09-18

In no other field of astrophysics has the impact of new instrumentation been as substantial as in the domain of exoplanets. Before 1995 our knowledge of exoplanets was mainly based on philosophical and theoretical considerations. The years that followed have been marked, instead, by surprising discoveries made possible by high-precision instruments. Over the past decade, the availability of new techniques has moved the focus of research from the detection to the characterization of exoplanets. Next-generation facilities will produce even more complementary data that will lead to a comprehensive view of exoplanet characteristics and, by comparison with theoretical models, to a better understanding of planet formation.

The influence of anharmonic and solvent effects on the theoretical vibrational spectra of the guanine-cytosine base pairs in Watson-Crick and Hoogsteen configurations.

PubMed

Bende, Attila; Muntean, Cristina M

2014-03-01

The theoretical IR and Raman spectra of the guanine-cytosine DNA base pairs in Watson-Crick and Hoogsteen configurations were computed using DFT method with M06-2X meta-hybrid GGA exchange-correlation functional, including the anharmonic corrections and solvent effects. The results for harmonic frequencies and their anharmonic corrections were compared with our previously calculated values obtained with the B3PW91 hybrid GGA functional. Significant differences were obtained for the anharmonic corrections calculated with the two different DFT functionals, especially for the stretching modes, while the corresponding harmonic frequencies did not differ considerable. For the Hoogtseen case the H⁺ vibration between the G-C base pair can be characterized as an asymmetric Duffing oscillator and therefore unrealistic anharmonic corrections for normal modes where this proton vibration is involved have been obtained. The spectral modification due to the anharmonic corrections, solvent effects and the influence of sugar-phosphate group for the Watson-Crick and Hoogsteen base pair configurations, respectively, were also discussed. For the Watson-Crick case also the influence of the stacking interaction on the theoretical IR and Raman spectra was analyzed. Including the anharmonic correction in our normal mode analysis is essential if one wants to obtain correct assignments of the theoretical frequency values as compared with the experimental spectra.

Masculinities in Higher Education: Theoretical and Practical Considerations

ERIC Educational Resources Information Center

Laker, Jason A., Ed.; Davis, Tracy, Ed.

2011-01-01

"Masculinities in Higher Education" provides empirical evidence, theoretical support, and developmental interventions for educators working with college men both in and out of the classroom. The critical philosophical perspective of the text challenges the status-quo and offers theoretically sound educational strategies to successfully promote…

The Role of Trait Emotional Intelligence in Academic Performance: Theoretical Overview and Empirical Update.

PubMed

Perera, Harsha N

2016-01-01

Considerable debate still exists among scholars over the role of trait emotional intelligence (TEI) in academic performance. The dominant theoretical position is that TEI should be orthogonal or only weakly related to achievement; yet, there are strong theoretical reasons to believe that TEI plays a key role in performance. The purpose of the current article is to provide (a) an overview of the possible theoretical mechanisms linking TEI with achievement and (b) an update on empirical research examining this relationship. To elucidate these theoretical mechanisms, the overview draws on multiple theories of emotion and regulation, including TEI theory, social-functional accounts of emotion, and expectancy-value and psychobiological model of emotion and regulation. Although these theoretical accounts variously emphasize different variables as focal constructs, when taken together, they provide a comprehensive picture of the possible mechanisms linking TEI with achievement. In this regard, the article redresses the problem of vaguely specified theoretical links currently hampering progress in the field. The article closes with a consideration of directions for future research.

An additional study and implementation of tone calibrated technique of modulation

NASA Technical Reports Server (NTRS)

Rafferty, W.; Bechtel, L. K.; Lay, N. E.

1985-01-01

The Tone Calibrated Technique (TCT) was shown to be theoretically free from an error floor, and is only limited, in practice, by implementation constraints. The concept of the TCT transmission scheme along with a baseband implementation of a suitable demodulator is introduced. Two techniques for the generation of the TCT signal are considered: a Manchester source encoding scheme (MTCT) and a subcarrier based technique (STCT). The results are summarized for the TCT link computer simulation. The hardware implementation of the MTCT system is addressed and the digital signal processing design considerations involved in satisfying the modulator/demodulator requirements are outlined. The program findings are discussed and future direction are suggested based on conclusions made regarding the suitability of the TCT system for the transmission channel presently under consideration.

Demand management: enabling patients to use medical care appropriately.

PubMed

Vickery, D M; Lynch, W D

1995-05-01

A rationale is presented for considering demand management as well as supply management (managed care) in the current debate on health care reform. Demand management is the support of individuals so that they may make rational health and medical decisions based on a consideration of benefits and risks. The concept of demand for medical services is examined within a theoretical framework of four components: morbidity, perceived need, patient preference, and nonhealth motives. Two components, perceived need and patient preference, are suggested to offer considerable potential for making utilization more appropriate and reducing costs. Current demand services and potential hazards related to their continued expansion are discussed.

Pressure dependence of band-gap and phase transitions in bulk CuX (X = Cl, Br, I)

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

Azhikodan, Dilna; Nautiyal, Tashi; Sharma, S.

2016-05-06

Usually a phase transition, in theoretical studies, is explored or verified by studying the total energy as a function of the volume considering various plausible phases. The intersection point, if any, of the free energy vs. volume curves for the different phases is then the indicator of the phase transition(s). The question is, can the theoretical study of a single phase alone indicate a phase transition? i.e. can we look beyond the phase under consideration through such a study? Using density-functional theory, we report a novel approach to suggest phase transition(s) through theoretical study of a single phase. Copper halidesmore » have been engaged for this study. These are direct band-gap semiconductors, with zinc blende structure at ambient conditions, and are reported to exhibit many phase transitions. We show that the study of volume dependence of energy band-gap in a single phase facilitates looking beyond the phase under consideration. This, when translated to pressures, reflects the phase transition pressures for CuX (X = Cl, Br, I) with an encouraging accuracy. This work thus offers a simple, yet reliable, approach based on electronic structure calculations to investigate new semiconducting materials for phase changes under pressure.« less

Plant Phenotyping through the Eyes of Complex Systems: Theoretical Considerations

NASA Astrophysics Data System (ADS)

Kim, J.

2017-12-01

Plant phenotyping is an emerging transdisciplinary research which necessitates not only the communication and collaboration of scientists from different disciplines but also the paradigm shift to a holistic approach. Complex system is defined as a system having a large number of interacting parts (or particles, agents), whose interactions give rise to non-trivial properties like self-organization and emergence. Plant ecosystems are complex systems which are continually morphing dynamical systems, i.e. self-organizing hierarchical open systems. Such systems are composed of many subunits/subsystems with nonlinear interactions and feedback. The throughput such as the flow of energy, matter and information is the key control parameter in complex systems. Information theoretic approaches can be used to understand and identify such interactions, structures and dynamics through reductions in uncertainty (i.e. entropy). The theoretical considerations based on network and thermodynamic thinking and exemplary analyses (e.g. dynamic process network, spectral entropy) of the throughput time series will be presented. These can be used as a framework to develop more discipline-specific fundamental approaches to provide tools for the transferability of traits between measurement scales in plant phenotyping. Acknowledgment: This work was funded by the Weather Information Service Engine Program of the Korea Meteorological Administration under Grant KMIPA-2012-0001.

Self-Psychology, Shame, and Adolescent Suicide: Theoretical and Practical Considerations.

ERIC Educational Resources Information Center

Shreve, Barry W.; Kunkel, Mark A.

1991-01-01

Discusses role of shame in adolescent suicidal behaviors using psychoanalytic self-psychology of Heinz Kohut as theoretical foundation. Describes shame as central component of suicidal behavior within context of adolescence. Offers theoretical explanation of adolescent suicidal behavior from self-psychology perspective. Presents suggestions for…

Photon-limited Sensing and Surveillance

DTIC Science & Technology

2015-01-29

considerable time delay). More specifically, there were four main outcomes from this work: • Improved understanding of the fundmental limitations of...that we design novel cameras for photon-limited settings based on the principles of CS. Most prior theoretical results in compressed sensing and related...inverse problems apply to idealized settings where the noise is i.i.d., and do not account for signal-dependent noise and physical sensing

Computational evidence for stable inorganic fullerene-like structures of ceramic and semiconductor materials

NASA Astrophysics Data System (ADS)

Chang, Ch; Patzer, A. B. C.; Sedlmayr, E.; Steinke, T.; Sülzle, D.

2001-12-01

Theoretical electronic structure techniques have become an indispensible and powerful means for predicting molecular properties and designing new materials. Based on a density functional approach and guided by geometric considerations we provide evidence for some specific inorganic fullerene-like cage molecules of ceramic and semiconductor materials which exhibit high energetic stability and point group symmetry as well as nearly perfect spherical shape.

Determination of hydroxide and carbonate contents of alkaline electrolytes containing zinc

NASA Technical Reports Server (NTRS)

Otterson, D. A.

1975-01-01

A method to prevent zinc interference with the titration of OH- and CO3-2 ions in alkaline electrolytes with standard acid is presented. The Ba-EDTA complex was tested and shown to prevent zinc interference with acid-base titrations without introducing other types of interference. Theoretical considerations indicate that this method can be used to prevent interference by other metals.

Very Massive Stars and the upper end of the IMF

NASA Astrophysics Data System (ADS)

Crowther, P.

2013-06-01

I discuss theoretical and observational evidence regarding the existence of Very Massive Stars (VMS) with initial masses significantly in excess of 100~Mo. Theoretical evidence includes consideration of the (classical) Eddington limit, while observational evidence involves efforts to interpret photometric and spectroscopic observations of the brightest stars in young, high mass clusters (R136a, Arches, NGC 3603), including new VLT/SINFONI and HST/STIS spectroscopy plus consideration of multiplicity (binaries and higher order systems).

Anatomy of the Higgs fits: A first guide to statistical treatments of the theoretical uncertainties

NASA Astrophysics Data System (ADS)

Fichet, Sylvain; Moreau, Grégory

2016-04-01

The studies of the Higgs boson couplings based on the recent and upcoming LHC data open up a new window on physics beyond the Standard Model. In this paper, we propose a statistical guide to the consistent treatment of the theoretical uncertainties entering the Higgs rate fits. Both the Bayesian and frequentist approaches are systematically analysed in a unified formalism. We present analytical expressions for the marginal likelihoods, useful to implement simultaneously the experimental and theoretical uncertainties. We review the various origins of the theoretical errors (QCD, EFT, PDF, production mode contamination…). All these individual uncertainties are thoroughly combined with the help of moment-based considerations. The theoretical correlations among Higgs detection channels appear to affect the location and size of the best-fit regions in the space of Higgs couplings. We discuss the recurrent question of the shape of the prior distributions for the individual theoretical errors and find that a nearly Gaussian prior arises from the error combinations. We also develop the bias approach, which is an alternative to marginalisation providing more conservative results. The statistical framework to apply the bias principle is introduced and two realisations of the bias are proposed. Finally, depending on the statistical treatment, the Standard Model prediction for the Higgs signal strengths is found to lie within either the 68% or 95% confidence level region obtained from the latest analyses of the 7 and 8 TeV LHC datasets.

Integrating Motivational Interviewing and Brief Behavioral Activation Therapy: Theoretical and Practical Considerations

PubMed Central

Balán, Iván C.; Lejuez, C. W.; Hoffer, Marcela; Blanco, Carlos

2017-01-01

Behavioral Activation and specifically the Brief Behavioral Activation Therapy for Depression (BATD) has a strong record of empirical support but its focus on practical out of session activation-based assignments can lead to poor levels of adherence if efforts to enhance motivation are not prioritized. Towards this end, this manuscript describes the assimilative integration of Motivational Interviewing (MI) and BATD to improve clinical outcomes by integrating MI's focus on building and maintaining motivation to change into BATD. The manuscript provides an overview of MI and BATD, theoretical issue raised in integrating the two approaches, and examples of how this integration results in a nondirective and motivation-focused approach to conducting BATD. PMID:29151779

On the contribution of Heinrich Bruns to theoretical geometrical optics. With consideration of his correspondence with scientists of the Zeiss Company in Jena 1888-1893. (German Title: Über den Beitrag von Heinrich Bruns zur theoretischen geometrischen Optik Unter Berücksichtigung seines Briefwechsels mit Wissenschaftlern der Zeiss-Werke in Jena 1888-1893)

NASA Astrophysics Data System (ADS)

Ilgauds, Hans-Joachim; Münzel, Gisela

This paper describes the works of Heinrich Bruns, director of the Leipzig University Observatory, on theoretical geometrical optics, which followed an outstanding tradition in Leipzig. Bruns and his pupils did not stop at theoretical considerations, but applied their findings to practical questions. Bruns' correspondence with opticians of the Zeiss Company in Jena, so far known only fragmentarily, gives impressive evidence of their friendly relationship characterized by mutual regard and stimulation.

The Importance of Theoretical Frameworks and Mathematical Constructs in Designing Digital Tools

ERIC Educational Resources Information Center

Trinter, Christine

2016-01-01

The increase in availability of educational technologies over the past few decades has not only led to new practice in teaching mathematics but also to new perspectives in research, methodologies, and theoretical frameworks within mathematics education. Hence, the amalgamation of theoretical and pragmatic considerations in digital tool design…

Integrating professionalism teaching into undergraduate medical education in the UK setting.

PubMed

Goldie, John

2008-06-01

This paper examines how professionalism teaching might be integrated into undergraduate medical education in the United Kingdom setting. It advocates adopting an outcome-based approach to curriculum planning, using the Scottish Deans' Medical Curriculum Group's (SDMCG) outcomes as a starting point. In discussing the curricular content, potential learning methods and strategies, theoretical considerations are explored. Student selection, assessment and strategies for optimising the educational environment are also considered.

Portfolio theory and the alternative decision rule of cost-effectiveness analysis: theoretical and practical considerations.

PubMed

Sendi, Pedram; Al, Maiwenn J; Gafni, Amiram; Birch, Stephen

2004-05-01

Bridges and Terris (Soc. Sci. Med. (2004)) critique our paper on the alternative decision rule of economic evaluation in the presence of uncertainty and constrained resources within the context of a portfolio of health care programs (Sendi et al. Soc. Sci. Med. 57 (2003) 2207). They argue that by not adopting a formal portfolio theory approach we overlook the optimal solution. We show that these arguments stem from a fundamental misunderstanding of the alternative decision rule of economic evaluation. In particular, the portfolio theory approach advocated by Bridges and Terris is based on the same theoretical assumptions that the alternative decision rule set out to relax. Moreover, Bridges and Terris acknowledge that the proposed portfolio theory approach may not identify the optimal solution to resource allocation problems. Hence, it provides neither theoretical nor practical improvements to the proposed alternative decision rule.

Experimental and Theoretical Study of Propeller Spinner/Shank Interference. M.S. Thesis

NASA Technical Reports Server (NTRS)

Cornell, C. C.

1986-01-01

A fundamental experimental and theoretical investigation into the aerodynamic interference associated with propeller spinner and shank regions was conducted. The research program involved a theoretical assessment of solutions previously proposed, followed by a systematic experimental study to supplement the existing data base. As a result, a refined computational procedure was established for prediction of interference effects in terms of interference drag and resolved into propeller thrust and torque components. These quantities were examined with attention to engineering parameters such as two spinner finess ratios, three blade shank forms, and two/three/four/six/eight blades. Consideration of the physics of the phenomena aided in the logical deduction of two individual interference quantities (cascade effects and spinner/shank juncture interference). These interference effects were semi-empirically modeled using existing theories and placed into a compatible form with an existing propeller performance scheme which provided the basis for examples of application.

Economic Analysis in the Pacific Northwest Land Resources Project: Theoretical Considerations and Preliminary Results

NASA Technical Reports Server (NTRS)

Morse, D. R. A.; Sahlberg, J. T.

1977-01-01

The Pacific Northwest Land Resources Inventory Demonstration Project i s an a ttempt to combine a whole spectrum of heterogeneous geographic, institutional and applications elements in a synergistic approach to the evaluation of remote sensing techniques. This diversity is the prime motivating factor behind a theoretical investigation of alternative economic analysis procedures. For a multitude of reasons--simplicity, ease of understanding, financial constraints and credibility, among others--cost-effectiveness emerges as the most practical tool for conducting such evaluation determinatIons in the Pacific Northwest. Preliminary findings in two water resource application areas suggest, in conformity with most published studies, that Lands at-aided data collection methods enjoy substantial cost advantages over alternative techniques. The pntential for sensitivity analysis based on cost/accuracy tradeoffs is considered on a theoretical plane in the absence of current accuracy figures concerning the Landsat-aided approach.

Developing a Manualized Occupational Therapy Diabetes Management Intervention: Resilient, Empowered, Active Living With Diabetes.

PubMed

Pyatak, Elizabeth A; Carandang, Kristine; Davis, Shain

2015-07-01

This article reports on the development of a manualized occupational therapy intervention for diabetes management. An initial theoretical framework and core content areas for a Stage I intervention manual were developed based on an in-depth needs assessment and review of existing literature. After evaluation by a panel of experts and completion of a feasibility study, the intervention was revised into a Stage 2 manual in preparation for a randomized study evaluating the intervention's efficacy. In developing the initial manual, we delineated core theoretical principles to allow for flexible application and tailoring of the intervention's content areas. Expert panel feedback and feasibility study results led to changes to the intervention structure and content as we developed the Stage 2 manual. Through describing this process, we illustrate the dynamic evolution of intervention manuals, which undergo revisions due to both theoretical and practical considerations at each stage of the research-to-clinical practice pipeline.

Theoretical Principles of Distance Education.

ERIC Educational Resources Information Center

Keegan, Desmond, Ed.

This book contains the following papers examining the didactic, academic, analytic, philosophical, and technological underpinnings of distance education: "Introduction"; "Quality and Access in Distance Education: Theoretical Considerations" (D. Randy Garrison); "Theory of Transactional Distance" (Michael G. Moore);…

Structural stiffness and Coulomb damping in compliant foil journal bearings: Theoretical considerations

NASA Astrophysics Data System (ADS)

Ku, C.-P. Roger; Heshmat, Hooshang

1994-07-01

Compliant foil bearings operate on either gas or liquid, which makes them very attractive for use in extreme environments such as in high-temperature aircraft turbine engines and cryogenic turbopumps. However, a lack of analytical models to predict the dynamic characteristics of foil bearings forces the bearing designer to rely on prototype testing, which is time-consuming and expensive. In this paper, the authors present a theoretical model to predict the structural stiffness and damping coefficients of the bump foil strip in a journal bearing or damper. Stiffness is calculated based on the perturbation of the journal center with respect to its static equilibrium position. The equivalent viscous damping coefficients are determined based on the area of a closed hysteresis loop of the journal center motion. The authors found, theoretically, that the energy dissipated from this loop was mostly contributed by the frictional motion between contact surfaces. In addition, the source and mechanism of the nonlinear behavior of the bump foil strips were examined. With the introduction of this enhanced model, the analytical tools are now available for the design of compliant foil bearings.

Theoretical study of mode evolution in active long tapered multimode fiber.

PubMed

Shi, Chen; Wang, Xiaolin; Zhou, Pu; Xu, Xiaojun; Lu, Qisheng

2016-08-22

A concise and effective model based on coupled mode theory to describe mode evolution in long tapered active fiber is presented in this manuscript. The mode coupling due to variation of core radius and slight perturbation have been analyzed and local gain with transverse spatial hole burning (TSHB) effect, loss and curvature have been taken into consideration in our model. On the base of this model, the mode evolution behaviors under different factors have been numerically investigated. Our model and results can provide instructive suggestions when designing long tapered fiber based laser and amplifiers.

Patient centredness in integrated care: results of a qualitative study based on a systems theoretical framework

PubMed Central

Lüdecke, Daniel

2014-01-01

Introduction Health care providers seek to improve patient-centred care. Due to fragmentation of services, this can only be achieved by establishing integrated care partnerships. The challenge is both to control costs while enhancing the quality of care and to coordinate this process in a setting with many organisations involved. The problem is to establish control mechanisms, which ensure sufficiently consideration of patient centredness. Theory and methods Seventeen qualitative interviews have been conducted in hospitals of metropolitan areas in northern Germany. The documentary method, embedded into a systems theoretical framework, was used to describe and analyse the data and to provide an insight into the specific perception of organisational behaviour in integrated care. Results The findings suggest that integrated care partnerships rely on networks based on professional autonomy in the context of reliability. The relationships of network partners are heavily based on informality. This correlates with a systems theoretical conception of organisations, which are assumed autonomous in their decision-making. Conclusion and discussion Networks based on formal contracts may restrict professional autonomy and competition. Contractual bindings that suppress the competitive environment have negative consequences for patient-centred care. Drawbacks remain due to missing self-regulation of the network. To conclude, less regimentation of integrated care partnerships is recommended. PMID:25411573

Patient centredness in integrated care: results of a qualitative study based on a systems theoretical framework.

PubMed

Lüdecke, Daniel

2014-10-01

Health care providers seek to improve patient-centred care. Due to fragmentation of services, this can only be achieved by establishing integrated care partnerships. The challenge is both to control costs while enhancing the quality of care and to coordinate this process in a setting with many organisations involved. The problem is to establish control mechanisms, which ensure sufficiently consideration of patient centredness. Seventeen qualitative interviews have been conducted in hospitals of metropolitan areas in northern Germany. The documentary method, embedded into a systems theoretical framework, was used to describe and analyse the data and to provide an insight into the specific perception of organisational behaviour in integrated care. The findings suggest that integrated care partnerships rely on networks based on professional autonomy in the context of reliability. The relationships of network partners are heavily based on informality. This correlates with a systems theoretical conception of organisations, which are assumed autonomous in their decision-making. Networks based on formal contracts may restrict professional autonomy and competition. Contractual bindings that suppress the competitive environment have negative consequences for patient-centred care. Drawbacks remain due to missing self-regulation of the network. To conclude, less regimentation of integrated care partnerships is recommended.

The effect of wall interference upon the aerodynamic characteristics of an airfoil spanning a closed-throat circular wind tunnel

NASA Technical Reports Server (NTRS)

Vincenti, Walter G; Graham, Donald J

1946-01-01

The results of a theoretical and experimental investigation of wall interference for an airfoil spanning a closed-throat circular wind tunnel are presented. Analytical equations are derived which relate the characteristics of an airfoil in the tunnel at subsonic speeds with the characteristics in free air. The analysis takes into consideration the effect of fluid compressibility and is based upon the assumption that the chord of the airfoil is small as compared with the diameter of the tunnel. The development is restricted to an untwisted, constant-chord airfoil spanning the middle of the tunnel. Brief theoretical consideration is also given to the problem of choking at high speeds. Results are then presented of tests to determine the low-speed characteristics of an NACA 4412 airfoil for two chord-diameter ratios. While, on the basis of these experiments, no appraisal is possible of the accuracy of the corrections at high speeds, the data indicate that at low Mach numbers the analytical results are valid, even for relatively large values of the chord-diameter ratio.

The Substorm Current Wedge Revisited

NASA Astrophysics Data System (ADS)

Kepko, Larry; McPherron, Robert; Apatenkov, Sergey; Baumjohann, Wolfgang; Birn, Joachim; Lester, Mark; Nakamura, Rumi; Pulkkinen, Tuija; Sergeev, Victor

2015-04-01

Almost 40 years ago the concept of the substorm current wedge was developed to explain the magnetic signatures observed on the ground and in geosynchronous orbit during substorm expansion. In the ensuing decades new observations, including radar and low-altitude spacecraft, MHD simulations, and theoretical considerations have tremendously advanced our understanding of this system. The AMPTE/IRM, THEMIS and Cluster missions have added considerable observational knowledge, especially on the important role of fast flows in producing the stresses that generate the substorm current wedge. Recent detailed, multi-spacecraft, multi-instrument observations both in the magnetosphere and in the ionosphere have brought a wealth of new information about the details of the temporal evolution and structure of the current system. In this paper, we briefly review recent in situ and ground-based observations and theoretical work that have demonstrated a need for an update of the original picture. We present a revised, time-dependent picture of the substorm current wedge that follows its evolution from the initial substorm flows through substorm expansion and recovery, and conclude by identifying open questions.

EEG-Neurofeedback as a Tool to Modulate Cognition and Behavior: A Review Tutorial

PubMed Central

Enriquez-Geppert, Stefanie; Huster, René J.; Herrmann, Christoph S.

2017-01-01

Neurofeedback is attracting renewed interest as a method to self-regulate one’s own brain activity to directly alter the underlying neural mechanisms of cognition and behavior. It not only promises new avenues as a method for cognitive enhancement in healthy subjects, but also as a therapeutic tool. In the current article, we present a review tutorial discussing key aspects relevant to the development of electroencephalography (EEG) neurofeedback studies. In addition, the putative mechanisms underlying neurofeedback learning are considered. We highlight both aspects relevant for the practical application of neurofeedback as well as rather theoretical considerations related to the development of new generation protocols. Important characteristics regarding the set-up of a neurofeedback protocol are outlined in a step-by-step way. All these practical and theoretical considerations are illustrated based on a protocol and results of a frontal-midline theta up-regulation training for the improvement of executive functions. Not least, assessment criteria for the validation of neurofeedback studies as well as general guidelines for the evaluation of training efficacy are discussed. PMID:28275344

Dynamical behaviours and control measures of rumour-spreading model with consideration of network topology

NASA Astrophysics Data System (ADS)

Zhu, Linhe; Zhao, Hongyong

2017-07-01

A series of online rumours have seriously influenced the normal production and living of people. This paper aims to study the combined impact of psychological factor, propagation delay, network topology and control strategy on rumour diffusion over the online social networks. Based on an online social network, which is seen as a scale-free network, we model the spread of rumours by using a delayed SIS (Susceptible and Infected) epidemic-like model with consideration of psychological factor and network topology. First, through theoretical analysis, we illustrate the boundedness of the density of rumour-susceptible individuals and rumour-infected individuals. Second, we obtain the basic reproduction number R0 and prove the stability of the non-rumour equilibrium point and the rumour-spreading equilibrium point. Third, control strategies, such as uniform immunisation control, proportional immunisation control, targeted immunisation control and optimum control, are put forward to restrain rumour diffusion. Meanwhile, we have compared the differences of these control strategies. Finally, some representative numerical simulations are performed to verify the theoretical analysis results.

Implementation science: a role for parallel dual processing models of reasoning?

PubMed Central

Sladek, Ruth M; Phillips, Paddy A; Bond, Malcolm J

2006-01-01

Background A better theoretical base for understanding professional behaviour change is needed to support evidence-based changes in medical practice. Traditionally strategies to encourage changes in clinical practices have been guided empirically, without explicit consideration of underlying theoretical rationales for such strategies. This paper considers a theoretical framework for reasoning from within psychology for identifying individual differences in cognitive processing between doctors that could moderate the decision to incorporate new evidence into their clinical decision-making. Discussion Parallel dual processing models of reasoning posit two cognitive modes of information processing that are in constant operation as humans reason. One mode has been described as experiential, fast and heuristic; the other as rational, conscious and rule based. Within such models, the uptake of new research evidence can be represented by the latter mode; it is reflective, explicit and intentional. On the other hand, well practiced clinical judgments can be positioned in the experiential mode, being automatic, reflexive and swift. Research suggests that individual differences between people in both cognitive capacity (e.g., intelligence) and cognitive processing (e.g., thinking styles) influence how both reasoning modes interact. This being so, it is proposed that these same differences between doctors may moderate the uptake of new research evidence. Such dispositional characteristics have largely been ignored in research investigating effective strategies in implementing research evidence. Whilst medical decision-making occurs in a complex social environment with multiple influences and decision makers, it remains true that an individual doctor's judgment still retains a key position in terms of diagnostic and treatment decisions for individual patients. This paper argues therefore, that individual differences between doctors in terms of reasoning are important considerations in any discussion relating to changing clinical practice. Summary It is imperative that change strategies in healthcare consider relevant theoretical frameworks from other disciplines such as psychology. Generic dual processing models of reasoning are proposed as potentially useful in identifying factors within doctors that may moderate their individual uptake of evidence into clinical decision-making. Such factors can then inform strategies to change practice. PMID:16725023

Implementation science: a role for parallel dual processing models of reasoning?

PubMed

Sladek, Ruth M; Phillips, Paddy A; Bond, Malcolm J

2006-05-25

A better theoretical base for understanding professional behaviour change is needed to support evidence-based changes in medical practice. Traditionally strategies to encourage changes in clinical practices have been guided empirically, without explicit consideration of underlying theoretical rationales for such strategies. This paper considers a theoretical framework for reasoning from within psychology for identifying individual differences in cognitive processing between doctors that could moderate the decision to incorporate new evidence into their clinical decision-making. Parallel dual processing models of reasoning posit two cognitive modes of information processing that are in constant operation as humans reason. One mode has been described as experiential, fast and heuristic; the other as rational, conscious and rule based. Within such models, the uptake of new research evidence can be represented by the latter mode; it is reflective, explicit and intentional. On the other hand, well practiced clinical judgments can be positioned in the experiential mode, being automatic, reflexive and swift. Research suggests that individual differences between people in both cognitive capacity (e.g., intelligence) and cognitive processing (e.g., thinking styles) influence how both reasoning modes interact. This being so, it is proposed that these same differences between doctors may moderate the uptake of new research evidence. Such dispositional characteristics have largely been ignored in research investigating effective strategies in implementing research evidence. Whilst medical decision-making occurs in a complex social environment with multiple influences and decision makers, it remains true that an individual doctor's judgment still retains a key position in terms of diagnostic and treatment decisions for individual patients. This paper argues therefore, that individual differences between doctors in terms of reasoning are important considerations in any discussion relating to changing clinical practice. It is imperative that change strategies in healthcare consider relevant theoretical frameworks from other disciplines such as psychology. Generic dual processing models of reasoning are proposed as potentially useful in identifying factors within doctors that may moderate their individual uptake of evidence into clinical decision-making. Such factors can then inform strategies to change practice.

An experimental and theoretical analysis of a foil-air bearing rotor system

NASA Astrophysics Data System (ADS)

Bonello, P.; Hassan, M. F. Bin

2018-01-01

Although there is considerable research on the experimental testing of foil-air bearing (FAB) rotor systems, only a small fraction has been correlated with simulations from a full nonlinear model that links the rotor, air film and foil domains, due to modelling complexity and computational burden. An approach for the simultaneous solution of the three domains as a coupled dynamical system, introduced by the first author and adopted by independent researchers, has recently demonstrated its capability to address this problem. This paper uses this approach, with further developments, in an experimental and theoretical study of a FAB-rotor test rig. The test rig is described in detail, including issues with its commissioning. The theoretical analysis uses a recently introduced modal-based bump foil model that accounts for interaction between the bumps and their inertia. The imposition of pressure constraints on the air film is found to delay the predicted onset of instability speed. The results lend experimental validation to a recent theoretically-based claim that the Gümbel condition may not be appropriate for a practical single-pad FAB. The satisfactory prediction of the salient features of the measured nonlinear behavior shows that the air film is indeed highly influential on the response, in contrast to an earlier finding.

Thrust characteristics of a series of convergent-divergent exhaust nozzles at subsonic and supersonic flight speeds

NASA Technical Reports Server (NTRS)

Fradenburgh, Evan A; Gorton, Gerald C; Beke, Andrew

1954-01-01

An experimental investigation of a series of four convergent-divergent exhaust nozzles was conducted in the Lewis 8-by-6 foot supersonic wind tunnel at Mach numbers of 0.1, 0.6, 1.6, and 2.0 over a range of nozzle pressure ratios. The thrust characteristics of these nozzles were determined by a pressure-integration technique. From a thrust standpoint, a nozzle designed to give uniform parallel flow at the exit had no advantage over the simple geometric design with conical convergent and divergent sections. The rapid-divergent nozzles might be competitive with the more gradual-divergent nozzles since the relatively short length of these nozzles would be advantageous from a weight standpoint and might result in smaller thrust losses due to friction. The thrusts, with friction losses neglected, were predicted satisfactorily by one-dimensional theory for the nozzles with relatively gradual divergence. The thrusts of the rapid-divergent designs were several percentages below the theoretical values at the design pressure ratio or above, while at low pressure ratios there was a considerable effect of free-stream Mach number, with thrusts considerably above theoretical values at subsonic speeds and somewhat above theoretical values at supersonic speeds. This Mach numb effect appeared to be related to the variation of the model base pressure with free-stream Mach number.

Target Coverage in Wireless Sensor Networks with Probabilistic Sensors

PubMed Central

Shan, Anxing; Xu, Xianghua; Cheng, Zongmao

2016-01-01

Sensing coverage is a fundamental problem in wireless sensor networks (WSNs), which has attracted considerable attention. Conventional research on this topic focuses on the 0/1 coverage model, which is only a coarse approximation to the practical sensing model. In this paper, we study the target coverage problem, where the objective is to find the least number of sensor nodes in randomly-deployed WSNs based on the probabilistic sensing model. We analyze the joint detection probability of target with multiple sensors. Based on the theoretical analysis of the detection probability, we formulate the minimum ϵ-detection coverage problem. We prove that the minimum ϵ-detection coverage problem is NP-hard and present an approximation algorithm called the Probabilistic Sensor Coverage Algorithm (PSCA) with provable approximation ratios. To evaluate our design, we analyze the performance of PSCA theoretically and also perform extensive simulations to demonstrate the effectiveness of our proposed algorithm. PMID:27618902

Accuracy optimization with wavelength tunability in overlay imaging technology

NASA Astrophysics Data System (ADS)

Lee, Honggoo; Kang, Yoonshik; Han, Sangjoon; Shim, Kyuchan; Hong, Minhyung; Kim, Seungyoung; Lee, Jieun; Lee, Dongyoung; Oh, Eungryong; Choi, Ahlin; Kim, Youngsik; Marciano, Tal; Klein, Dana; Hajaj, Eitan M.; Aharon, Sharon; Ben-Dov, Guy; Lilach, Saltoun; Serero, Dan; Golotsvan, Anna

2018-03-01

As semiconductor manufacturing technology progresses and the dimensions of integrated circuit elements shrink, overlay budget is accordingly being reduced. Overlay budget closely approaches the scale of measurement inaccuracies due to both optical imperfections of the measurement system and the interaction of light with geometrical asymmetries of the measured targets. Measurement inaccuracies can no longer be ignored due to their significant effect on the resulting device yield. In this paper we investigate a new approach for imaging based overlay (IBO) measurements by optimizing accuracy rather than contrast precision, including its effect over the total target performance, using wavelength tunable overlay imaging metrology. We present new accuracy metrics based on theoretical development and present their quality in identifying the measurement accuracy when compared to CD-SEM overlay measurements. The paper presents the theoretical considerations and simulation work, as well as measurement data, for which tunability combined with the new accuracy metrics is shown to improve accuracy performance.

Outcome regimes of binary raindrop collisions

NASA Astrophysics Data System (ADS)

Testik, Firat Y.

2009-11-01

This study delineates the physical conditions that are responsible for the occurrence of main outcome regimes (i.e., bounce, coalescence, and breakup) for binary drop collisions with a precipitation microphysics perspective. Physical considerations based on the collision kinetic energy and the surface energies of the colliding drops lead to the development of a theoretical regime diagram for the drop/raindrop collision outcomes in the We- p plane ( We — Weber number, p — raindrop diameter ratio). This theoretical regime diagram is supported by laboratory experimental observations of drop collisions using high-speed imaging. Results of this fundamental study bring in new insights into the quantitative understanding of drop dynamics, applications of which extend beyond precipitation microphysics. In particular, results of this drop collision study are expected to give impetus to the physics-based dynamic modeling of the drop size distributions that is essential for various typical modern engineering applications, including numerical modeling of evolution of raindrop size distribution in rain shaft.

Analysis of Implicit Uncertain Systems. Part 1: Theoretical Framework

DTIC Science & Technology

1994-12-07

Analysis of Implicit Uncertain Systems Part I: Theoretical Framework Fernando Paganini * John Doyle 1 December 7, 1994 Abst rac t This paper...Analysis of Implicit Uncertain Systems Part I: Theoretical Framework 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...model and a number of constraints relevant to the analysis problem under consideration. In Part I of this paper we propose a theoretical framework which

Thinking outside the ROCs: Designing decorrelated taggers (DDT) for jet substructure

DOE PAGES

Dolen, James; Harris, Philip; Marzani, Simone; ...

2016-05-26

Here, we explore the scale-dependence and correlations of jet substructure observables to improve upon existing techniques in the identification of highly Lorentz-boosted objects. Modified observables are designed to remove correlations from existing theoretically well-understood observables, providing practical advantages for experimental measurements and searches for new phenomena. We study such observables in W jet tagging and provide recommendations for observables based on considerations beyond signal and background efficiencies.

Memory-Efficient Analysis of Dense Functional Connectomes.

PubMed

Loewe, Kristian; Donohue, Sarah E; Schoenfeld, Mircea A; Kruse, Rudolf; Borgelt, Christian

2016-01-01

The functioning of the human brain relies on the interplay and integration of numerous individual units within a complex network. To identify network configurations characteristic of specific cognitive tasks or mental illnesses, functional connectomes can be constructed based on the assessment of synchronous fMRI activity at separate brain sites, and then analyzed using graph-theoretical concepts. In most previous studies, relatively coarse parcellations of the brain were used to define regions as graphical nodes. Such parcellated connectomes are highly dependent on parcellation quality because regional and functional boundaries need to be relatively consistent for the results to be interpretable. In contrast, dense connectomes are not subject to this limitation, since the parcellation inherent to the data is used to define graphical nodes, also allowing for a more detailed spatial mapping of connectivity patterns. However, dense connectomes are associated with considerable computational demands in terms of both time and memory requirements. The memory required to explicitly store dense connectomes in main memory can render their analysis infeasible, especially when considering high-resolution data or analyses across multiple subjects or conditions. Here, we present an object-based matrix representation that achieves a very low memory footprint by computing matrix elements on demand instead of explicitly storing them. In doing so, memory required for a dense connectome is reduced to the amount needed to store the underlying time series data. Based on theoretical considerations and benchmarks, different matrix object implementations and additional programs (based on available Matlab functions and Matlab-based third-party software) are compared with regard to their computational efficiency. The matrix implementation based on on-demand computations has very low memory requirements, thus enabling analyses that would be otherwise infeasible to conduct due to insufficient memory. An open source software package containing the created programs is available for download.

Memory-Efficient Analysis of Dense Functional Connectomes

PubMed Central

Loewe, Kristian; Donohue, Sarah E.; Schoenfeld, Mircea A.; Kruse, Rudolf; Borgelt, Christian

2016-01-01

The functioning of the human brain relies on the interplay and integration of numerous individual units within a complex network. To identify network configurations characteristic of specific cognitive tasks or mental illnesses, functional connectomes can be constructed based on the assessment of synchronous fMRI activity at separate brain sites, and then analyzed using graph-theoretical concepts. In most previous studies, relatively coarse parcellations of the brain were used to define regions as graphical nodes. Such parcellated connectomes are highly dependent on parcellation quality because regional and functional boundaries need to be relatively consistent for the results to be interpretable. In contrast, dense connectomes are not subject to this limitation, since the parcellation inherent to the data is used to define graphical nodes, also allowing for a more detailed spatial mapping of connectivity patterns. However, dense connectomes are associated with considerable computational demands in terms of both time and memory requirements. The memory required to explicitly store dense connectomes in main memory can render their analysis infeasible, especially when considering high-resolution data or analyses across multiple subjects or conditions. Here, we present an object-based matrix representation that achieves a very low memory footprint by computing matrix elements on demand instead of explicitly storing them. In doing so, memory required for a dense connectome is reduced to the amount needed to store the underlying time series data. Based on theoretical considerations and benchmarks, different matrix object implementations and additional programs (based on available Matlab functions and Matlab-based third-party software) are compared with regard to their computational efficiency. The matrix implementation based on on-demand computations has very low memory requirements, thus enabling analyses that would be otherwise infeasible to conduct due to insufficient memory. An open source software package containing the created programs is available for download. PMID:27965565

Complex technology of vacuum-arc processing of structural material surface

NASA Astrophysics Data System (ADS)

Arustamov, V. N.; Ashurov, Kh. B.; Kadyrov, Kh. Kh.; Khudoikulov, I. Kh.

2015-08-01

The development of environmentally friendly and energy-resource-saving technologies based on vacuum arc discharge is a topical problem in science and engineering. In view of their unique properties, cathode spots of a vacuum arc induce cleaning of the surface of an article (cathode) from various contaminations and pulsed thermal action on the surface layers. These processes occur in complex with vacuum-arc deposition of coatings in the same technological cycle, which makes it possible to considerably increase the efficiency of methods for changing physical, mechanical, and chemical properties of the surface of steel articles, which considerably increase their service life. Analysis of the formation of the temperature regime of the surface during vacuum arc action and of the parameters of the deposited coating will make it possible to optimize the regimes of complex treatment of the surfaces of articles and is of considerable theoretical and practical importance.

Theory and practice of clinical ethics support services: narrative and hermeneutical perspectives.

PubMed

Porz, Rouven; Landeweer, Elleke; Widdershoven, Guy

2011-09-01

In this paper we introduce narrative and hermeneutical perspectives to clinical ethics support services (CESS). We propose a threefold consideration of 'theory' and show how it is interwoven with 'practice' as we go along. First, we look at theory in its foundational role: in our case 'narrative ethics' and 'philosophical hermeneutics' provide a theoretical base for clinical ethics by focusing on human identities entangled in stories and on moral understanding as a dialogical process. Second, we consider the role of theoretical notions in helping practitioners to understand their situation in clinical ethics practice, by using notions like 'story', 'responsibility', or 'vulnerability' to make explicit and explain their practical experience. Such theoretical notions help us to interpret clinical situations from an ethical perspective and to foster moral awareness of practitioners. And, thirdly, we examine how new theoretical concepts are developed by interpreting practice, using practice to form and improve our ethical theory. In this paper, we discuss this threefold use of theory in clinical ethics support services by reflecting on our own theoretical assumptions, methodological steps and practical experiences as ethicists, and by providing examples from our daily work. In doing so, we illustrate that theory and practice are interwoven, as theoretical understanding is dependent upon practical experience, and vice-versa. © 2011 Blackwell Publishing Ltd.

Signal-to-noise analysis of a birefringent spectral zooming imaging spectrometer

NASA Astrophysics Data System (ADS)

Li, Jie; Zhang, Xiaotong; Wu, Haiying; Qi, Chun

2018-05-01

Study of signal-to-noise ratio (SNR) of a novel spectral zooming imaging spectrometer (SZIS) based on two identical Wollaston prisms is conducted. According to the theory of radiometry and Fourier transform spectroscopy, we deduce the theoretical equations of SNR of SZIS in spectral domain with consideration of the incident wavelength and the adjustable spectral resolution. An example calculation of SNR of SZIS is performed over 400-1000 nm. The calculation results indicate that SNR with different spectral resolutions of SZIS can be optionally selected by changing the spacing between the two identical Wollaston prisms. This will provide theoretical basis for the design, development and engineering of the developed imaging spectrometer for broad spectrum and SNR requirements.

On the theoretical velocity distribution and flow resistance in natural channels

NASA Astrophysics Data System (ADS)

Moramarco, Tommaso; Dingman, S. Lawrence

2017-12-01

The velocity distribution in natural channels is of considerable interest for streamflow measurements to obtain information on discharge and flow resistance. This study focuses on the comparison of theoretical velocity distributions based on 1) entropy theory, and 2) the two-parameter power law. The analysis identifies the correlation between the parameters of the distributions and defines their dependence on the geometric and hydraulic characteristics of the channel. Specifically, we investigate how the parameters are related to the flow resistance in terms of Manning roughness, shear velocity and water surface slope, and several formulae showing their relationships are proposed. Velocity measurements carried out in the past 20 years at Ponte Nuovo gauged section along the Tiber River, central Italy, are the basis for the analysis.

[Euthanasia and the paradoxes of autonomy].

PubMed

Siqueira-Batista, Rodrigo; Schramm, Fermin Roland

2008-01-01

The principle of respect for autonomy has proved very useful for bioethical arguments in favor of euthanasia. However unquestionable its theoretical efficacy, countless aporiae can be raised when conducting a detailed analysis of this concept, probably checkmating it. Based on such considerations, this paper investigates the principle of autonomy, starting with its origins in Greek and Christian traditions, and then charting some of its developments in Western cultures through to its modern formulation, a legacy of Immanuel Kant. The main paradoxes of this concept are then presented in the fields of philosophy, biology, psychoanalysis and politics, expounding several of the theoretical difficulties to be faced in order to make its applicability possible within the scope of decisions relating to the termination of life.

Equilibrium swelling properties of polyampholytic hydrogels

NASA Astrophysics Data System (ADS)

English, Anthony E.; Mafé, Salvador; Manzanares, José A.; Yu, Xiahong; Grosberg, Alexander Yu.; Tanaka, Toyoichi

1996-06-01

The role of counter ions and ion dissociation in establishing the equilibrium swelling of balanced and unbalanced polyampholytic hydrogels has been investigated experimentally and theoretically. The swelling dependence on both the net charge offset and the external bath salt concentration has been examined using an acrylamide based polyampholytic hydrogels. By careful consideration of the swelling kinetics, we illustrate the effects of ion dissociation equilibria and counter ion shielding in polyampholytic hydrogels near their balance point where both polyelectrolyte and polyampholyte effects are present. The theory considers a Flory type swelling model where the Coulombic interactions between fixed ions in the hydrogel resemble those of an ionic solid with a Debye screening factor. Theoretical predictions from this model are in qualitative agreement with our experimental results.

Surface normal coupling to multiple-slot and cover-slotted silicon nanocrystalline waveguides and ring resonators

NASA Astrophysics Data System (ADS)

Covey, John; Chen, Ray T.

2014-03-01

Grating couplers are ideal for coupling into the tightly confined propagation modes of semiconductor waveguides. In addition, nonlinear optics has benefited from the sub-diffraction limit confinement of horizontal slot waveguides. By combining these two advancements, slot-based nonlinear optics with mode areas less than 0.02 μm2 can become as routine as twisting fiber connectors together. Surface normal fiber alignment to a chip is also highly desirable from time, cost, and manufacturing considerations. To meet these considerable design challenges, a custom genetic algorithm is created which, starting from purely random designs, creates a unique four stage grating coupler for two novel horizontal slot waveguide platforms. For horizontal multiple-slot waveguides filled with silicon nanocrystal, a theoretical fiber-towaveguide coupling efficiency of 68% is obtained. For thin silicon waveguides clad with optically active silicon nanocrystal, known as cover-slot waveguides, a theoretical fiber-to-waveguide coupling efficiency of 47% is obtained, and 1 dB and 3 dB theoretical bandwidths of 70 nm and 150 nm are obtained, respectively. Both waveguide platforms are fabricated from scratch, and their respective on-chip grating couplers are experimentally measured from a standard single mode fiber array that is mounted surface normally. The horizontal multiple-slot grating coupler achieved an experimental 60% coupling efficiency, and the horizontal cover-slot grating coupler achieved an experimental 38.7% coupling efficiency, with an extrapolated 1 dB bandwidth of 66 nm. This report demonstrates the promise of genetic algorithm-based design by reducing to practice the first large bandwidth vertical grating coupler to a novel silicon nanocrystal horizontal cover-slot waveguide.

Ion and electron temperatures in the topside ionosphere

NASA Technical Reports Server (NTRS)

Munninghoff, D. E.

1979-01-01

Experimental and theoretical ion and electron temperatures in the topside ionosphere were investigated. Experimental results came from an analysis of incoherent scatter data taken at Arecibo, Puerto Rico. Consideration of the energy balance equations gave the theoretical ion and electron temperatures.

Power allocation for target detection in radar networks based on low probability of intercept: A cooperative game theoretical strategy

NASA Astrophysics Data System (ADS)

Shi, Chenguang; Salous, Sana; Wang, Fei; Zhou, Jianjiang

2017-08-01

Distributed radar network systems have been shown to have many unique features. Due to their advantage of signal and spatial diversities, radar networks are attractive for target detection. In practice, the netted radars in radar networks are supposed to maximize their transmit power to achieve better detection performance, which may be in contradiction with low probability of intercept (LPI). Therefore, this paper investigates the problem of adaptive power allocation for radar networks in a cooperative game-theoretic framework such that the LPI performance can be improved. Taking into consideration both the transmit power constraints and the minimum signal to interference plus noise ratio (SINR) requirement of each radar, a cooperative Nash bargaining power allocation game based on LPI is formulated, whose objective is to minimize the total transmit power by optimizing the power allocation in radar networks. First, a novel SINR-based network utility function is defined and utilized as a metric to evaluate power allocation. Then, with the well-designed network utility function, the existence and uniqueness of the Nash bargaining solution are proved analytically. Finally, an iterative Nash bargaining algorithm is developed that converges quickly to a Pareto optimal equilibrium for the cooperative game. Numerical simulations and theoretic analysis are provided to evaluate the effectiveness of the proposed algorithm.

Recent advances of nanotechnology in medicine and engineering

NASA Astrophysics Data System (ADS)

Nobile, Lucio; Nobile, Stefano

2016-05-01

The aim of this paper is to give an overview of some advances of nanotechnology in medicine and engineering, exploring typical applications of these emerging technologies. The mechanical properties of such small structures determine their utility and are therefore of considerable interest. Based on nanometer scale tests, a theoretical model to predict the bending strength of a nanobeam is proposed. A fracture approach which takes into account imperfections on the beam surface and crack growth is employed.

The synthesis and structure of a potential immunosuppressant: N-mycophenoyl malonic acid dimethyl ester

NASA Astrophysics Data System (ADS)

Siebert, Agnieszka; Cholewiński, Grzegorz; Garwolińska, Dorota; Olejnik, Adrian; Rachoń, Janusz; Chojnacki, Jarosław

2018-01-01

The synthesis of a potential immunosuppressant, i.e. dimethyl ester of N-mycophenoyl malonic acid was optimized in the reaction of mycophenolic acid (MPA) with amino malonic dimethyl ester in the presence of propanephosphonic anhydride (T3P) as a coupling reagent. The structural properties of the obtained MPA derivative were investigated by NMR, MS and single crystal X-ray diffraction methods. Theoretical considerations of conformational flexibility based on DFT calculations are presented.

Turbomachinery group for cold energy concept application

NASA Astrophysics Data System (ADS)

Alavi, S.; Arpi, A.; Ascani, M.; Cerri, G.; Chennaoui, L.; Manni, A.

2017-08-01

The paper discusses a special attempt to improve COP and compressor capacity. Theoretical and experimental results are presented, and they show a very positive trend. Compressor and Expander Group impellers are selected among the Car Engine Turbocharger Units. Modifications are proposed to achieve the best performance, taking the peculiar characteristics of the refrigerant into consideration. Tests have confirmed the positive saving trend, which can reach up to 22%-24% for an optimized bleed vapour generator and turbomachinery-based booster unit.

Experimental relevance of global properties of time-delayed feedback control.

PubMed

von Loewenich, Clemens; Benner, Hartmut; Just, Wolfram

2004-10-22

We show by means of theoretical considerations and electronic circuit experiments that time-delayed feedback control suffers from severe global constraints if transitions at the control boundaries are discontinuous. Subcritical behavior gives rise to small basins of attraction and thus limits the control performance. The reported properties are, on the one hand, universal since the mechanism is based on general arguments borrowed from bifurcation theory and, on the other hand, directly visible in experimental time series.

Recent advances of nanotechnology in medicine and engineering

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

Nobile, Lucio; Nobile, Stefano

The aim of this paper is to give an overview of some advances of nanotechnology in medicine and engineering, exploring typical applications of these emerging technologies. The mechanical properties of such small structures determine their utility and are therefore of considerable interest. Based on nanometer scale tests, a theoretical model to predict the bending strength of a nanobeam is proposed. A fracture approach which takes into account imperfections on the beam surface and crack growth is employed.

Spring roll dielectric elastomer actuators for a portable force feedback glove

NASA Astrophysics Data System (ADS)

Zhang, Rui; Lochmatter, Patrick; Kunz, Andreas; Kovacs, Gabor

2006-03-01

Miniature spring roll dielectric elastomer actuators for a novel kinematic-free force feedback concept were manufactured and experimentally characterized. The actuators exhibited a maximum blocking force of 7.2 N and a displacement of 5 mm. The theoretical considerations based on the material's incompressibility were discussed in order to estimate the actuator behavior under blocked-strain activation and free-strain activation. One prototype was built for the demonstration of the proposed force feedback concept.

Fluctuations in energy loss and their implications for dosimetry and radiobiology

NASA Technical Reports Server (NTRS)

Baily, N. A.; Steigerwalt, J. E.

1972-01-01

Serious consideration of the physics of energy deposition indicates that a fundamental change in the interpretation of absorbed dose is required at least for considerations of effects in biological systems. In addition, theoretical approaches to radiobiology and microdosimetry seem to require statistical considerations incorporating frequency distributions of the magnitude of the event sizes within the volume of interest.

Optical vector network analyzer with improved accuracy based on polarization modulation and polarization pulling.

PubMed

Li, Wei; Liu, Jian Guo; Zhu, Ning Hua

2015-04-15

We report a novel optical vector network analyzer (OVNA) with improved accuracy based on polarization modulation and stimulated Brillouin scattering (SBS) assisted polarization pulling. The beating between adjacent higher-order optical sidebands which are generated because of the nonlinearity of an electro-optic modulator (EOM) introduces considerable error to the OVNA. In our scheme, the measurement error is significantly reduced by removing the even-order optical sidebands using polarization discrimination. The proposed approach is theoretically analyzed and experimentally verified. The experimental results show that the accuracy of the OVNA is greatly improved compared to a conventional OVNA.

A formula for calculating theoretical photoelectron fluxes resulting from the He/+/ 304 A solar spectral line

NASA Technical Reports Server (NTRS)

Richards, P. G.; Torr, D. G.

1981-01-01

A simplified method for the evaluation of theoretical photoelectron fluxes in the upper atmosphere resulting from the solar radiation at 304 A is presented. The calculation is based on considerations of primary and cascade (secondary) photoelectron production in the two-stream model, where photoelectron transport is described by two electron streams, one moving up and one moving down, and of loss rates due to collisions with neutral gases and thermal electrons. The calculation is illustrated for the case of photoelectrons at an energy of 24.5 eV, and it is noted that the 24.5-eV photoelectron flux may be used to monitor variations in the solar 304 A flux. Theoretical calculations based on various ionization and excitation cross sections of Banks et al. (1974) are shown to be in generally good agreement with AE-E measurements taken between 200 and 235 km, however the use of more recent, larger cross sections leads to photoelectron values a factor of two smaller than observations but in agreement with previous calculations. It is concluded that a final resolution of the photoelectron problem may depend on a reevaluation of the inelastic electron collision cross sections.

Theoretical study of gas hydrate decomposition kinetics--model development.

PubMed

Windmeier, Christoph; Oellrich, Lothar R

2013-10-10

In order to provide an estimate of the order of magnitude of intrinsic gas hydrate dissolution and dissociation kinetics, the "Consecutive Desorption and Melting Model" (CDM) is developed by applying only theoretical considerations. The process of gas hydrate decomposition is assumed to comprise two consecutive and repetitive quasi chemical reaction steps. These are desorption of the guest molecule followed by local solid body melting. The individual kinetic steps are modeled according to the "Statistical Rate Theory of Interfacial Transport" and the Wilson-Frenkel approach. All missing required model parameters are directly linked to geometric considerations and a thermodynamic gas hydrate equilibrium model.

"Journal of Space Economics - theoretical and practical considerations"

NASA Astrophysics Data System (ADS)

Beldavs, VZ; Sommers, J.

2017-09-01

This paper will address theoretical and practical considerations for the emerging field of space economics and propose an editorial policy for a journal of space economics to provide a forum for the discussion of space economics issues. It is anticipated that initially the Journal of Space Economics will operate from two different nodes one offering a European perspective (University of Latvia) and the other a U.S. perspective (University of Wisconsin at Milwaukee). The first edition of the Journal of Space Economics will focus on issues likely to arise during the course of the International Lunar Decade 2020-2030.

Unique considerations in the design and experimental evaluation of tailored wings with elastically produced chordwise camber

NASA Technical Reports Server (NTRS)

Rehfield, Lawrence W.; Zischka, Peter J.; Fentress, Michael L.; Chang, Stephen

1992-01-01

Some of the unique considerations that are associated with the design and experimental evaluation of chordwise deformable wing structures are addressed. Since chordwise elastic camber deformations are desired and must be free to develop, traditional rib concepts and experimental methodology cannot be used. New rib design concepts are presented and discussed. An experimental methodology based upon the use of a flexible sling support and load application system has been created and utilized to evaluate a model box beam experimentally. Experimental data correlate extremely well with design analysis predictions based upon a beam model for the global properties of camber compliance and spanwise bending compliance. Local strain measurements exhibit trends in agreement with intuition and theory but depart slightly from theoretical perfection based upon beam-like behavior alone. It is conjectured that some additional refinement of experimental technique is needed to explain or eliminate these (minor) departures from asymmetric behavior of upper and lower box cover strains. Overall, a solid basis for the design of box structures based upon the bending method of elastic camber production has been confirmed by the experiments.

Theoretical considerations on the optogalvanic detection of laser induced fluorescence in atmospheric pressure atomizers

NASA Astrophysics Data System (ADS)

Omenetto, N.; Smith, B. W.; Winefordner, J. D.

1989-01-01

Several theoretical considerations are given on the potential and practical capabilities of a detector of fluorescence radiation whose operating principle is based on a multi-step excitation-ionization scheme involving the fluorescence photons as the first excitation step. This detection technique, which was first proposed by MATVEEVet al. [ Zh. Anal Khim.34, 846 (1979)], combines two independent atomizers, one analytical cell for the excitation of the sample fluorescence and one cell, filled with pure analyte atomic vapor, acting as the ionization detector. One laser beam excites the analyte fluorescence in the analytical cell and one (or two) laser beams are used to ionize the excited atoms in the detector. Several different causes of signal and noise are evaluated, together with a discussion on possible analytical atom reservoirs (flames, furnaces) and laser sources which could be used with this approach. For properly devised conditions, i.e. optical saturation of the fluorescence and unity ionization efficiency, detection limits well below pg/ml in solution and well below femtograms as absolute amounts in furnaces can be predicted. However, scattering problems, which are absent in a conventional laser-enhanced ionization set-up, may be important in this approach.

Migration of nanoparticles from plastic packaging materials containing carbon black into foodstuffs

PubMed Central

Bott, Johannes; Störmer, Angela; Franz, Roland

2014-01-01

Carbon black was investigated to assess and quantify the possibility that nanoparticles might migrate out of plastic materials used in the food packaging industry. Two types of carbon black were incorporated in low-density polyethylene (LDPE) and polystyrene (PS) at 2.5% and 5.0% loading (w/w), and then subjected to migration studies. The samples were exposed to different food simulants according to European Union Plastics Regulation 10/2011, simulating long-term storage with aqueous and fatty foodstuffs. Asymmetric flow field-flow fractionation (AF4) coupled to a multi-angle laser light-scattering (MALLS) detector was used to separate, characterise and quantify the potential release of nanoparticles. The AF4 method was successful in differentiating carbon black from other matrix components, such as extracted polymer chains, in the migration solution. At a detection limit of 12 µg kg−1, carbon black did not migrate from the packaging material into food simulants. The experimental findings are in agreement with theoretical considerations based on migration modelling. From both the experimental findings and theoretical considerations, it can be concluded that carbon black does not migrate into food once it is incorporated into a plastics food contact material. PMID:25105506

Migration of nanoparticles from plastic packaging materials containing carbon black into foodstuffs.

PubMed

Bott, Johannes; Störmer, Angela; Franz, Roland

2014-01-01

Carbon black was investigated to assess and quantify the possibility that nanoparticles might migrate out of plastic materials used in the food packaging industry. Two types of carbon black were incorporated in low-density polyethylene (LDPE) and polystyrene (PS) at 2.5% and 5.0% loading (w/w), and then subjected to migration studies. The samples were exposed to different food simulants according to European Union Plastics Regulation 10/2011, simulating long-term storage with aqueous and fatty foodstuffs. Asymmetric flow field-flow fractionation (AF4) coupled to a multi-angle laser light-scattering (MALLS) detector was used to separate, characterise and quantify the potential release of nanoparticles. The AF4 method was successful in differentiating carbon black from other matrix components, such as extracted polymer chains, in the migration solution. At a detection limit of 12 µg kg⁻¹, carbon black did not migrate from the packaging material into food simulants. The experimental findings are in agreement with theoretical considerations based on migration modelling. From both the experimental findings and theoretical considerations, it can be concluded that carbon black does not migrate into food once it is incorporated into a plastics food contact material.

Substorm Current Wedge Revisited

NASA Astrophysics Data System (ADS)

Kepko, L.; McPherron, R. L.; Amm, O.; Apatenkov, S.; Baumjohann, W.; Birn, J.; Lester, M.; Nakamura, R.; Pulkkinen, T. I.; Sergeev, V.

2015-07-01

Almost 40 years ago the concept of the substorm current wedge was developed to explain the magnetic signatures observed on the ground and in geosynchronous orbit during substorm expansion. In the ensuing decades new observations, including radar and low-altitude spacecraft, MHD simulations, and theoretical considerations have tremendously advanced our understanding of this system. The AMPTE/IRM, THEMIS and Cluster missions have added considerable observational knowledge, especially on the important role of fast flows in producing the stresses that generate the substorm current wedge. Recent detailed, multi-spacecraft, multi-instrument observations both in the magnetosphere and in the ionosphere have brought a wealth of new information about the details of the temporal evolution and structure of the current system. While the large-scale picture remains valid, the new details call for revision and an update of the original view. In this paper we briefly review the historical development of the substorm current wedge, review recent in situ and ground-based observations and theoretical work, and discuss the current active research areas. We conclude with a revised, time-dependent picture of the substorm current wedge that follows its evolution from the initial substorm flows through substorm expansion and recovery.

Relaxation-based distance measurements between a nitroxide and a lanthanide spin label

NASA Astrophysics Data System (ADS)

Jäger, H.; Koch, A.; Maus, V.; Spiess, H. W.; Jeschke, G.

2008-10-01

Distance measurements by electron paramagnetic resonance techniques between labels attached to biomacromolecules provide structural information on systems that cannot be crystallized or are too large to be characterized by NMR methods. However, existing techniques are limited in their distance range and sensitivity. It is anticipated by theoretical considerations that these limits could be extended by measuring the enhancement of longitudinal relaxation of a nitroxide label due to a lanthanide complex label at cryogenic temperatures. The relaxivity of the dysprosium complex with the macrocyclic ligand DOTA can be determined without direct measurements of longitudinal relaxation rates of the lanthanide and without recourse to model compounds with well defined distance by analyzing the dependence of relaxation enhancement on either temperature or concentration in homogeneous glassy frozen solutions. Relaxivities determined by the two calibration techniques are in satisfying agreement with each other. Error sources for both techniques are examined. A distance of about 2.7 nm is measured in a model compound of the type nitroxide-spacer-lanthanide complex and is found in good agreement with the distance in a modeled structure. Theoretical considerations suggest that an increase of the upper distance limit requires measurements at lower fields and temperatures.

Theory and practical considerations of multilayer dielectric thin-film stacks in Ag-coated hollow waveguides.

PubMed

Bledt, Carlos M; Melzer, Jeffrey E; Harrington, James A

2014-02-01

This analysis explores the theory and design of dielectric multilayer reflection-enhancing thin film stacks based on high and low refractive index alternating layers of cadmium sulfide (CdS) and lead sulfide (PbS) on silver (Ag)-coated hollow glass waveguides (HGWs) for low loss transmission at midinfrared wavelengths. The fundamentals for determining propagation losses in such multilayer thin-film-coated Ag hollow waveguides is thoroughly discussed, and forms the basis for further theoretical analysis presented in this study. The effects on propagation loss resulting from several key parameters of these multilayer thin film stacks is further explored in order to bridge the gap between results predicted through calculation under ideal conditions and deviations from such ideal models that often arise in practice. In particular, the effects on loss due to the number of dielectric thin film layers deposited, deviation from ideal individual layer thicknesses, and surface roughness related scattering losses are presented and thoroughly investigated. Through such extensive theoretical analysis the level of understanding of the underlying loss mechanisms of multilayer thin-film Ag-coated HGWs is greatly advanced, considerably increasing the potential practical development of next-generation ultralow-loss mid-IR Ag/multilayer dielectric-coated HGWs.

Scaffold microstructure effects on functional and mechanical performance: Integration of theoretical and experimental approaches for bone tissue engineering applications.

PubMed

Cavo, Marta; Scaglione, Silvia

2016-11-01

The really nontrivial goal of tissue engineering is combining all scaffold micro-architectural features, affecting both fluid-dynamical and mechanical performance, to obtain a fully functional implant. In this work we identified an optimal geometrical pattern for bone tissue engineering applications, best balancing several graft needs which correspond to competing design goals. In particular, we investigated the occurred changes in graft behavior by varying pore size (300μm, 600μm, 900μm), interpore distance (equal to pore size or 300μm fixed) and pores interconnection (absent, 45°-oriented, 90°-oriented). Mathematical considerations and Computational Fluid Dynamics (CFD) tools, here combined in a complete theoretical model, were carried out to this aim. Poly-lactic acid (PLA) based samples were realized by 3D printing, basing on the modeled architectures. A collagen (COL) coating was also realized on grafts surface and the interaction between PLA and COL, besides the protein contribution to graft bioactivity, was evaluated. Scaffolds were extensively characterized; human articular cells were used to test their biocompatibility and to evaluate the theoretical model predictions. Grafts fulfilled both the chemical and physical requirements. Finally, a good agreement was found between the theoretical model predictions and the experimental data, making these prototypes good candidates for bone graft replacements. Copyright © 2016 Elsevier B.V. All rights reserved.

Developing a Manualized Occupational Therapy Diabetes Management Intervention: Resilient, Empowered, Active Living With Diabetes

PubMed Central

Pyatak, Elizabeth A.; Carandang, Kristine; Davis, Shain

2016-01-01

This article reports on the development of a manualized occupational therapy intervention for diabetes management. An initial theoretical framework and core content areas for a Stage 1 intervention manual were developed based on an in-depth needs assessment and review of existing literature. After evaluation by a panel of experts and completion of a feasibility study, the intervention was revised into a Stage 2 manual in preparation for a randomized study evaluating the intervention’s efficacy. In developing the initial manual, we delineated core theoretical principles to allow for flexible application and tailoring of the intervention’s content areas. Expert panel feedback and feasibility study results led to changes to the intervention structure and content as we developed the Stage 2 manual. Through describing this process, we illustrate the dynamic evolution of intervention manuals, which undergo revisions due to both theoretical and practical considerations at each stage of the research-to-clinical practice pipeline. PMID:26594741

Analysis of quasi-hybrid solid rocket booster concepts for advanced earth-to-orbit vehicles

NASA Technical Reports Server (NTRS)

Zurawski, Robert L.; Rapp, Douglas C.

1987-01-01

A study was conducted to assess the feasibility of quasi-hybrid solid rocket boosters for advanced Earth-to-orbit vehicles. Thermochemical calculations were conducted to determine the effect of liquid hydrogen addition, solids composition change plus liquid hydrogen addition, and the addition of an aluminum/liquid hydrogen slurry on the theoretical performance of a PBAN solid propellant rocket. The space shuttle solid rocket booster was used as a reference point. All three quasi-hybrid systems theoretically offer higher specific impulse when compared with the space shuttle solid rocket boosters. However, based on operational and safety considerations, the quasi-hybrid rocket is not a practical choice for near-term Earth-to-orbit booster applications. Safety and technology issues pertinent to quasi-hybrid rocket systems are discussed.

Theoretical model of ruminant adipose tissue metabolism in relation to the whole animal.

PubMed

Baldwin, R L; Yang, Y T; Crist, K; Grichting, G

1976-09-01

Based on theoretical considerations and experimental data, estimates of contributions of adipose tissue to energy expenditures in a lactating cow and a growing steer were developed. The estimates indicate that adipose energy expenditures range between 5 and 10% of total animal heat production dependent on productive function and diet. These energy expenditures can be partitioned among maintenance (3%), lipogenesis (1-5%) and lipolysis and triglyceride resynthesis (less thatn 1.0%). Specific sites at which acute and chronic effectors can act to produce changes in adipose function, and changes in adipose function produced by diet and during pregnancy, lactation and aging were discussed with emphasis being placed on the need for additional, definitive studies of specific interactions among pregnancy, diet, age, lactation and growth in producing ruminants.

Particle Transport and Size Sorting in Bubble Microstreaming Flow

NASA Astrophysics Data System (ADS)

Thameem, Raqeeb; Rallabandi, Bhargav; Wang, Cheng; Hilgenfeldt, Sascha

2014-11-01

Ultrasonic driving of sessile semicylindrical bubbles results in powerful steady streaming flows that are robust over a wide range of driving frequencies. In a microchannel, this flow field pattern can be fine-tuned to achieve size-sensitive sorting and trapping of particles at scales much smaller than the bubble itself; the sorting mechanism has been successfully described based on simple geometrical considerations. We investigate the sorting process in more detail, both experimentally (using new parameter variations that allow greater control over the sorting) and theoretically (incorporating the device geometry as well as the superimposed channel flow into an asymptotic theory). This results in optimized criteria for size sorting and a theoretical description that closely matches the particle behavior close to the bubble, the crucial region for size sorting.

A Theoretical Perspective of Learning in the Pacific Context: A Sociocultural Perspective

ERIC Educational Resources Information Center

Phan, Huy P.

2010-01-01

This theoretical article discusses the importance of learning approaches in sociocultural contexts. Our discussion synthesizes previous empirical research studies, taking into consideration the importance of individuals' cultural background and environmental settings. Research studies by Marton and Saljo (1976) and others (Biggs, 1987; Watkins…

Evolution or Revolution: Mobility Requirements for the AirLand Battle Future Concept

DTIC Science & Technology

1991-02-20

analysis and the model a theoretical framework for tactical mobility is established. The considerations for tactical mobility on the future battlefield are...examined in the context of the theoretical framework . Finally, using the criteria of sufficiency, feasibility, and the time/space continuum, the

Visual Literacy. . .An Overview of Theory and Practice.

ERIC Educational Resources Information Center

DeSantis, Lucille Burbank; Pett, Dennis W.

Visual Literacy is a field that encompasses a variety of theoretical constructs and practical considerations relating to communicating with visual signs. The theoretical constructs that influence visual communication primarily fall into two closely interrelated categories: those that relate to the individuals involved in the communication process,…

Collisional & Nonlinear Radiative Processes for Development of Coherent UV & XUV Sources.

DTIC Science & Technology

1987-04-01

4- Charles K. Rhodes in the vicinity of an atomic unit, (e/a ). Extant theoretical work, however, 0 predicted ridiculously low rates...of 14 210 W/cm . These experiments clearly demonstrated that standard theoretical techniques were incapable, by a discrepancy as great as several...experiments were clearly in contradiction to all theoretical treatments, of which there is a considerable number (16-21). This unexpected result, of course

Development and Application of Low Energy X-Ray and Electron Physics.

DTIC Science & Technology

1984-03-14

the other with a specially designed streak camera. D. X-Ray Optics 1. Analyzers and Monochromators Along with our theoretical model calculations for...stearate and lead behenate (2d-spacings of 80, 100 and 120 A, respectively) that have reached the theoretically predicted values for peak, integrated...energy secondary electron energy photoemission, considerably more theoretical and ex- region. The secondary electron spectrum peaks at about perimental

Theoretical Bases of Polymer Photodegradation and Photooxidation,

DTIC Science & Technology

1987-10-15

UNCLASSIFIED FTD- AD(RS)T-E868-87 F/G 7/6 NL MhEEOEE~~h EhiIIIEEEEEI -M Mi(ROC PY RESOLUtIO(N TEST CHA NA ION- A j ~A M R ~ . DEiC FILE CME ( 1 ) FTD-ID...In addition, when such processes are carried out in an atmosphere of air, numerous carbonyl, carboxyl , hydroxyl etc. groups form along the polymer...photoaging this should be multilateral with consideration of the following basic processes [ 1 -93: ...... 1 . Photochemical reactions of the actual

Atomistic characterization of SAM coatings as gate insulators in Si-based FET devices

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

Gala, F.; Zollo, G.

2014-06-19

Many nano-material systems are currently under consideration as possible candidates for gate dielectric insulators in both metal-oxide-semiconductor (MOSFET) and organic (OFET) field-effect transistors. In this contribution, the possibility of employing self-assembled monolayers (SAMs) of hydroxylated octadecyltrichlorosilane (OTS) chains on a (111) Si substrate as gate dielectrics is discussed; in particular ab initio theoretical simulations have been employed to study the structural properties, work function modifications, and the insulating properties of OTS thin film coatings on Si substrates.

Atomistic characterization of SAM coatings as gate insulators in Si-based FET devices

NASA Astrophysics Data System (ADS)

Gala, F.; Zollo, G.

2014-06-01

Many nano-material systems are currently under consideration as possible candidates for gate dielectric insulators in both metal-oxide-semiconductor (MOSFET) and organic (OFET) field-effect transistors. In this contribution, the possibility of employing self-assembled monolayers (SAMs) of hydroxylated octadecyltrichlorosilane (OTS) chains on a (111) Si substrate as gate dielectrics is discussed; in particular ab initio theoretical simulations have been employed to study the structural properties, work function modifications, and the insulating properties of OTS thin film coatings on Si substrates.

Moiré assisted fractional quantum Hall state spectroscopy

DOE PAGES

Wu, Fengcheng; MacDonald, A. H.

2016-12-14

Intra-Landau level excitations in the fractional quantum Hall regime are not accessible via optical absorption measurements. Here we point out that optical probes are enabled by the periodic potentials produced by a moire pattern. Our observation is motivated by the recent observations of fractional quantum Hall incompressible states in moire-patterned graphene on a hexagonal boron nitride substrate, and is theoretically based on f-sum rule considerations supplemented by a perturbative analysis of the influence of the moire potential on many-body states.

Rupture politique et enseignement de l'histoire en Afrique du Sud: Les manuels de l'enseignement primaire. (Political rupture and the teaching of history in South Africa: Handbooks of primary-level teaching.)

ERIC Educational Resources Information Center

Carpentier, Claude

2000-01-01

Analyzes the content of South African history text books from the primary level upwards and from the 1980s to the most recent publications. The considerable changes in the content of these books seem to be based on two different theoretical models: the multicultural model and the notion of the universality of humanity. (Contains 40 references.)…

College Fund Raising Using Theoretical Perspectives to Understand Donor Motives

ERIC Educational Resources Information Center

Mann, Timothy

2007-01-01

This paper provides senior leadership teams with a body of literature that will guide the development of "fund-raising strategy" and provides an "interdisciplinary" context for understanding "donor motives". Consideration of these "theoretical foundations" can help shape the fund-raising philosophy of the institution. These perspectives also have…

Optimizing the Long-Term Retention of Skills: Structural and Analytic Approaches to Skill Maintenance

DTIC Science & Technology

1990-08-01

evidence for a surprising degree of long-term skill retention. We formulated a theoretical framework , focusing on the importance of procedural reinstatement...considerable forgetting over even relatively short retention intervals. We have been able to place these studies in the same general theoretical framework developed

Emotions and Motivation in Mathematics Education: Theoretical Considerations and Empirical Contributions

ERIC Educational Resources Information Center

Schukajlow, Stanislaw; Rakoczy, K.; Pekrun, R.

2017-01-01

Emotions and motivation are important prerequisites, mediators, and outcomes of learning and achievement. In this article, we first review major theoretical approaches and empirical findings in research on students' emotions and motivation in mathematics, including a discussion of how classroom instruction can support emotions and motivation.…

Library Hospitality: Some Preliminary Considerations

ERIC Educational Resources Information Center

Johnson, Eric D. M.; Kazmer, Michelle M.

2011-01-01

Library scholars and practitioners have frequently reflected on the various factors that in combination make up a hospitable library, but there has been little theoretical synthesis of the notion of the library as a place of hospitality. The hospitality industry provides a rich vein of theoretical material from which to draw definitions of…

Theoretical Backgrounds: Internet for Training Teachers and the Development of the HyperCard Internet Primer.

ERIC Educational Resources Information Center

Anderson, Daniel K.

1996-01-01

Discusses theoretical backgrounds for training teachers to use the Internet, including: a history of the Internet, education reform, technology and education, teacher training, affective domains, learning styles, and evaluation. Instructional design considerations are described for developing the HyperCard Internet Primer, software introducing…

A Theoretical Framework towards Understanding of Emotional and Behavioural Difficulties

ERIC Educational Resources Information Center

Poulou, Maria S.

2014-01-01

Children's emotional and behavioural difficulties are the result of multiple individual, social and contextual factors working in concert. The current paper proposes a theoretical framework to interpret students' emotional and behavioural difficulties in schools, by taking into consideration teacher-student relationships, students'…

Monitoring progression of clinical reasoning skills during health sciences education using the case method - a qualitative observational study.

PubMed

Orban, Kristina; Ekelin, Maria; Edgren, Gudrun; Sandgren, Olof; Hovbrandt, Pia; Persson, Eva K

2017-09-11

Outcome- or competency-based education is well established in medical and health sciences education. Curricula are based on courses where students develop their competences and assessment is also usually course-based. Clinical reasoning is an important competence, and the aim of this study was to monitor and describe students' progression in professional clinical reasoning skills during health sciences education using observations of group discussions following the case method. In this qualitative study students from three different health education programmes were observed while discussing clinical cases in a modified Harvard case method session. A rubric with four dimensions - problem-solving process, disciplinary knowledge, character of discussion and communication - was used as an observational tool to identify clinical reasoning. A deductive content analysis was performed. The results revealed the students' transition over time from reasoning based strictly on theoretical knowledge to reasoning ability characterized by clinical considerations and experiences. Students who were approaching the end of their education immediately identified the most important problem and then focused on this in their discussion. Practice knowledge increased over time, which was seen as progression in the use of professional language, concepts, terms and the use of prior clinical experience. The character of the discussion evolved from theoretical considerations early in the education to clinical reasoning in later years. Communication within the groups was supportive and conducted with a professional tone. Our observations revealed progression in several aspects of students' clinical reasoning skills on a group level in their discussions of clinical cases. We suggest that the case method can be a useful tool in assessing quality in health sciences education.

The Information Architecture of E-Commerce: An Experimental Study on User Performance and Preference

NASA Astrophysics Data System (ADS)

Wan Mohd, Wan Abdul Rahim; Md Noor, Nor Laila; Mehad, Shafie

Too often, designers of e-commerce web sites use models, concepts, guidelines, and designs that focus on the artifacts while ignoring the context in which the artifacts will be used. Furthermore, the link between culture and usability in web site IA phenomenon is still considered as uncharted area, as it lacks much theoretical consideration. In an effort toward addressing the aforementioned issues, our study provides a theoretical and empirical link between cultural and usability through the application of ‘Venustas' (Delight) drawn from the architectural field and Hofstede's cultural dimensions. We use Islamic culture as the case study and report on the experiment to investigate the effect of the IA designs based on the cultural dimensions on e-commerce web sites. The result provides partial empirical support to the theorized link between culture and usability based on the usability measurement on user performance and preference. In addition, practical web site IA cultural design prescriptions are also provided.

Research on logistics scheduling based on PSO

NASA Astrophysics Data System (ADS)

Bao, Huifang; Zhou, Linli; Liu, Lei

2017-08-01

With the rapid development of e-commerce based on the network, the logistics distribution support of e-commerce is becoming more and more obvious. The optimization of vehicle distribution routing can improve the economic benefit and realize the scientific of logistics [1]. Therefore, the study of logistics distribution vehicle routing optimization problem is not only of great theoretical significance, but also of considerable value of value. Particle swarm optimization algorithm is a kind of evolutionary algorithm, which is based on the random solution and the optimal solution by iteration, and the quality of the solution is evaluated through fitness. In order to obtain a more ideal logistics scheduling scheme, this paper proposes a logistics model based on particle swarm optimization algorithm.

Dual-Enrollment High-School Graduates' College-Enrollment Considerations

ERIC Educational Resources Information Center

Damrow, Roberta J.

2017-01-01

This quantitative study examined college enrollment considerations of dual-enrollment students enrolling at one Wisconsin credit-granting technical college. A combined college-choice theoretical framework guided this quantitative study that addressed two research questions: To what extent, if any, did the number of dual credits predict likelihood…

Searching for a Common Ground--A Literature Review of Empirical Research on Scientific Inquiry Activities

ERIC Educational Resources Information Center

Rönnebeck, Silke; Bernholt, Sascha; Ropohl, Mathias

2016-01-01

Despite the importance of scientific inquiry in science education, researchers and educators disagree considerably regarding what features define this instructional approach. While a large body of literature addresses theoretical considerations, numerous empirical studies investigate scientific inquiry on quite different levels of detail and also…

Theoretical consideration of the energy resolution in planar HPGe detectors for low energy X-rays

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

Samedov, Victor V.

In this work, theoretical consideration of the processes in planar High Purity Ge (HPGe) detectors for low energy X-rays using the random stochastic processes formalism was carried out. Using the random stochastic processes formalism, the generating function of the processes of X-rays registration in a planar HPGe detector was derived. The power serial expansions of the detector amplitude and the variance in terms of the inverse bias voltage were derived. The coefficients of these expansions allow determining the Fano factor, electron mobility lifetime product, nonuniformity of the trap density, and other characteristics of the semiconductor material. (authors)

Achromatization In The 3 To 5 μm Spectral Region With Visible Light Transmitting Materials

NASA Astrophysics Data System (ADS)

McDowell, M. W.; Klee, H. W.

1984-04-01

The theoretical performances of several f/1.5 triplet lenses suitable for use in the 3 to 5um spectral region are compared. Examples are given in which all the materials used have a finite visible transmittance. As centering errors can thus be considerably reduced, it is expected that such a lens will in practice approach more closely its theoretical performance. These lenses are also considerably less sensitive to manufacturing tolerances as a result of lower index materials, and the use of low dn/dT materials offers other advantages over the more usual silicon-germanium combination.

Theoretical and Practical Considerations for Combating Mental Illness Stigma in Health Care.

PubMed

Ungar, Thomas; Knaak, Stephanie; Szeto, Andrew C H

2016-04-01

Reducing the stigma and discrimination associated with mental illness is becoming an increasingly important focus for research, policy, programming and intervention work. While it has been well established that the healthcare system is one of the key environments in which persons with mental illnesses experience stigma and discrimination there is little published literature on how to build and deliver successful anti-stigma programs in healthcare settings, towards healthcare providers in general, or towards specific types of practitioners. Our paper intends to address this gap by providing a set of theoretical considerations for guiding the design and implementation of anti-stigma interventions in healthcare.

Theoretical and practical outline of the Copenhagen PACT narrative-based exercise counselling manual to promote physical activity in post-therapy cancer survivors.

PubMed

Midtgaard, Julie

2013-02-01

Sedentary behaviour and reduced exercise capacity are potential persisting effects of anti-cancer therapy that may predispose to serious health conditions. It is well-established that physical exercise may prevent some of these problems. However, the extent to which cancer survivors are able to adopt long-term physical activity habits depends largely on their motivation. This theoretical paper aims to outline how researchers and practitioners can draw from Antonovsky's salutogenetic theory and White & Epston's Narrative Therapy to develop and implement intervention efforts centered on promotion of long-term physical activity behaviour, while at the same time increasing the individual cancer survivor's sense of meaning and personal health resources. The Copenhagen PACT (Physical Activity after Cancer Treatment) Study targeting adoption and maintenance of regular physical activity in post-therapy cancer survivors is briefly presented including a brief review of the theoretical rationale behind the psychological component of the intervention, i.e. a narrative-based exercise counselling programme. Subsequently, particular attention is given to the core principles, different components and structure of the counselling manual including sample questions and examples of written documents that have emanated from the individual counselling sessions. The discussion includes consideration of some methodological challenges that arise when attempting to evaluate narrative-based interventions in the context of physical activity promotion in cancer rehabilitation and survivorship care.

Ludwig von Bertalanffy's organismic view on the theory of evolution.

PubMed

Drack, Manfred

2015-03-01

Ludwig von Bertalanffy was a key figure in the advancement of theoretical biology. His early considerations already led him to recognize the necessity of considering the organism as a system, as an organization of parts and processes. He termed the resulting research program organismic biology, which he extended to all basic questions of biology and almost all areas of biology, hence also to the theory of evolution. This article begins by outlining the rather unknown (because often written in German) research of Bertalanffy in the field of theoretical biology. The basics of the organismic approach are then described. This is followed by Bertalanffy's considerations on the theory of evolution, in which he used methods from theoretical biology and then introduced his own, organismic, view on evolution, leading to the demand for finding laws of evolution. Finally, his view on the concept of homology is presented. © 2015 Wiley Periodicals, Inc.

Subjective Age Bias: A Motivational and Information Processing Approach

ERIC Educational Resources Information Center

Teuscher, Ursina

2009-01-01

There is broad empirical evidence, but still a lack of theoretical explanations, for the phenomenon that most older people feel considerably younger than their real age. In this article, a measurement model of subjective age was assessed, and two independent theoretical approaches are proposed: (1) a motivational approach assuming that the age…

Point and Click: Theoretical and Phenomenological Reflections on the Digitization of Early Childhood Education

ERIC Educational Resources Information Center

Mangen, Anne

2010-01-01

This article presents some theoretical-methodological reflections on the current state of the art of research on information and communication technology (ICT) in early childhood education. The implementation of ICT in preschool has triggered considerable research activity on the educational potential of digital technologies. Numerous projects and…

Tax Law System

ERIC Educational Resources Information Center

Tsindeliani, Imeda A.

2016-01-01

The article deals with consideration of the actual theoretic problems of the subject and system of tax law in Russia. The theoretical approaches to determination of the nature of separate institutes of tax law are represented. The existence of pandect system intax law building as financial law sub-branch of Russia is substantiated. The goal of the…

The Government-Higher Education Institution Relationship: Theoretical Considerations from the Perspective of Agency Theory

ERIC Educational Resources Information Center

Kivisto, Jussi

2005-01-01

This article introduces the agency theory to the field of higher education research. By applying agency theory to the inter-organisational relationship between government and higher education institutions, it is possible to illustrate general problems facing control and governance in a more theoretical and analytical way. The conceptual arsenal…

Physics in one dimension: theoretical concepts for quantum many-body systems.

PubMed

Schönhammer, K

2013-01-09

Various sophisticated approximation methods exist for the description of quantum many-body systems. It was realized early on that the theoretical description can simplify considerably in one-dimensional systems and various exact solutions exist. The focus in this introductory paper is on fermionic systems and the emergence of the Luttinger liquid concept.

Acting Out; Theoretical and Clinical Aspects.

ERIC Educational Resources Information Center

Abt, Lawrence Edwin, Ed.; Weissman, Stuart L.

The beneficial and harmful effects of acting out are studied in a series of short essays by numerous authors. Included are four articles on the theoretical and dynamic considerations of acting out, along with five clinical manifestations of acting out involving suicide and criminality in adolescents and adults. Special forms of harmful acting out…

Researching Education Policy in a Globalized World: Theoretical and Methodological Considerations

ERIC Educational Resources Information Center

Lingard, Bob

2009-01-01

This paper shows how globalization has given rise to a number of new theoretical and methodological issues for doing education policy analysis linked to globalization's impact within critical social science. Critical policy analysis has always required critical "reflexivity" and awareness of the "positionality" of the policy analyst. However, as…

Theoretical study of the ionospheric G factor

NASA Technical Reports Server (NTRS)

Hagenbuch, K. M.

1972-01-01

A derivation from kinetic theory of the energy balance equation used in wave interaction work is reviewed. Then G is defined and two models for G are presented: one, a model based on Gerjuoy-Stein cross sections for both O2 and N2; the other based on a more recent model for O2 cross sections. The two models differ considerably in their temperature dependence. The limits of applicability of the useful energy balance equation (hence of the concept of G) are discussed and it is found that no difficulty arises unless the transmitter power is more than 1000 times that now employed at the present operating frequency.

Compound parabolic concentrator probe for efficient light collection in spectroscopy of biological tissue

NASA Astrophysics Data System (ADS)

Tanaka, Kazunori; Pacheco, Marcos T. T.; Brennan, James F., III; Itzkan, Irving; Berger, Andrew J.; Dasari, Ramachandra R.; Feld, Michael S.

1996-02-01

We describe a compound parabolic concentrator (CPC)-based probe for enhanced signal collection in the spectroscopy of biological tissues. Theoretical considerations governing signal enhancement compared with conventional collection methods are given. A ray-tracing program was used to analyze the throughput of CPC's with shape deviations and surface imperfections. A modified CPC shape with 99% throughput was discovered. A 4.4-mm-long CPC was manufactured and incorporated into an optical fiber-based near-infrared Raman spectrometer system. For human tissue samples, light collection was enhanced by a factor of 7 compared with collection with 0.29-NA optical fibers.

Exploring the critical quality attributes and models of smart homes.

PubMed

Ted Luor, Tainyi; Lu, Hsi-Peng; Yu, Hueiju; Lu, Yinshiu

2015-12-01

Research on smart homes has significantly increased in recent years owing to their considerably improved affordability and simplicity. However, the challenge is that people have different needs (or attitudes toward smart homes), and provision should be tailored to individuals. A few studies have classified the functions of smart homes. Therefore, the Kano model is first adopted as a theoretical base to explore whether the functional classifications of smart homes are attractive or necessary, or both. Second, three models and test user attitudes toward three function types of smart homes are proposed. Based on the Kano model, the principal results, namely, two "Attractive Quality" and nine "Indifferent Quality" items, are found. Verification of the hypotheses also indicates that the entertainment, security, and automation functions are significantly correlated with the variables "perceive useful" and "attitude." Cost consideration is negatively correlated with attitudes toward entertainment and automation. Results suggest that smart home providers should survey user needs for their product instead of merely producing smart homes based on the design of the builder or engineer. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Theoretical Limits of Energy Density in Silicon-Carbon Composite Anode Based Lithium Ion Batteries.

PubMed

Dash, Ranjan; Pannala, Sreekanth

2016-06-17

Silicon (Si) is under consideration as a potential next-generation anode material for the lithium ion battery (LIB). Experimental reports of up to 40% increase in energy density of Si anode based LIBs (Si-LIBs) have been reported in literature. However, this increase in energy density is achieved when the Si-LIB is allowed to swell (volumetrically expand) more than graphite based LIB (graphite-LIB) and beyond practical limits. The volume expansion of LIB electrodes should be negligible for applications such as automotive or mobile devices. We determine the theoretical bounds of Si composition in a Si-carbon composite (SCC) based anode to maximize the volumetric energy density of a LIB by constraining the external dimensions of the anode during charging. The porosity of the SCC anode is adjusted to accommodate the volume expansion during lithiation. The calculated threshold value of Si was then used to determine the possible volumetric energy densities of LIBs with SCC anode (SCC-LIBs) and the potential improvement over graphite-LIBs. The level of improvement in volumetric and gravimetric energy density of SCC-LIBs with constrained volume is predicted to be less than 10% to ensure the battery has similar power characteristics of graphite-LIBs.

Correcting horsepower measurements to a standard temperature

NASA Technical Reports Server (NTRS)

Sparrow, Stanwood W

1925-01-01

This report discusses the relation between the temperature of the air at the entrance to the carburetor and the power developed by the engine. Its scope is limited to a consideration of the range of temperatures likely to result from changes of season, locality, or altitude, since its primary aim is the finding of a satisfactory basis for correcting power measurements to a standard temperature. The tests upon which this report is based were made upon aviation engines in the Altitude Laboratory of the Bureau of Standards. From the results of over 1,600 tests it is concluded that if calculations be based on the assumption that the indicated horsepower of an engine varies inversely as the square root of the absolute temperature of the carburetor air the values obtained will check closely experimental measurements. The extent to which this relationship would be expected from theoretical considerations is discussed and some suggestions are given relative to the use of this relationship in correcting horsepower measurements. (author)

Intersections of Critical Systems Thinking and Community Based Participatory Research: A Learning Organization Example with the Autistic Community

PubMed Central

Raymaker, Dora M

2016-01-01

Critical systems thinking (CST) and community based participatory research (CBPR) are distinct approaches to inquiry which share a primary commitment to holism and human emancipation, as well as common grounding in critical theory and emancipatory and pragmatic philosophy. This paper explores their intersections and complements on a historical, philosophical, and theoretical level, and then proposes a hybrid approach achieved by applying CBPR's principles and considerations for operationalizing emancipatory practice to traditional systems thinking frameworks and practices. This hybrid approach is illustrated in practice with examples drawn from of the implementation of the learning organization model in an action research setting with the Autistic community. Our experience of being able to actively attend to, and continuously equalize, power relations within an organizational framework that otherwise has great potential for reinforcing power inequity suggests CBPR's principles and considerations for operationalizing emancipatory practice could be useful in CST settings, and CST's vocabulary, methods, and clarity around systems thinking concepts could be valuable to CBPR practioners. PMID:27833398

Intersections of Critical Systems Thinking and Community Based Participatory Research: A Learning Organization Example with the Autistic Community.

PubMed

Raymaker, Dora M

2016-10-01

Critical systems thinking (CST) and community based participatory research (CBPR) are distinct approaches to inquiry which share a primary commitment to holism and human emancipation, as well as common grounding in critical theory and emancipatory and pragmatic philosophy. This paper explores their intersections and complements on a historical, philosophical, and theoretical level, and then proposes a hybrid approach achieved by applying CBPR's principles and considerations for operationalizing emancipatory practice to traditional systems thinking frameworks and practices. This hybrid approach is illustrated in practice with examples drawn from of the implementation of the learning organization model in an action research setting with the Autistic community. Our experience of being able to actively attend to, and continuously equalize, power relations within an organizational framework that otherwise has great potential for reinforcing power inequity suggests CBPR's principles and considerations for operationalizing emancipatory practice could be useful in CST settings, and CST's vocabulary, methods, and clarity around systems thinking concepts could be valuable to CBPR practioners.

Dynamic properties of ionospheric plasma turbulence driven by high-power high-frequency radiowaves

NASA Astrophysics Data System (ADS)

Grach, S. M.; Sergeev, E. N.; Mishin, E. V.; Shindin, A. V.

2016-11-01

A review is given of the current state-of-the-art of experimental studies and the theoretical understanding of nonlinear phenomena that occur in the ionospheric F-layer irradiated by high-power high-frequency ground-based transmitters. The main focus is on the dynamic features of high-frequency turbulence (plasma waves) and low-frequency turbulence (density irregularities of various scales) that have been studied in experiments at the Sura and HAARP heating facilities operated in temporal and frequency regimes specially designed with consideration of the characteristic properties of nonlinear processes in the perturbed ionosphere using modern radio receivers and optical instruments. Experimental results are compared with theoretical turbulence models for a magnetized collisional plasma in a high-frequency electromagnetic field, allowing the identification of the processes responsible for the observed features of artificial ionospheric turbulence.

[Parameters of cardiac muscle repolarization on the electrocardiogram when changing anatomical and electric position of the heart].

PubMed

Chaĭkovskiĭ, I A; Baum, O V; Popov, L A; Voloshin, V I; Budnik, N N; Frolov, Iu A; Kovalenko, A S

2014-01-01

While discussing the diagnostic value of the single channel electrocardiogram a set of theoretical considerations emerges inevitably, one of the most important among them is the question about dependence of the electrocardiogram parameters from the direction of electrical axis of heart. In other words, changes in what of electrocardiogram parameters are in fact liable to reflect pathological processes in myocardium, and what ones are determined by extracardiac factors, primarily by anatomic characteristics of patients. It is arguable that while analyzing electrocardiogram it is necessary to orient to such physiologically based informative indexes as ST segment displacement. Also, symmetry of the T wave shape is an important parameter which is independent of patients anatomic features. The results obtained are of interest for theoretical and applied aspects of the biophysics of the cardiac electric field.

Explicating an Evidence-Based, Theoretically Informed, Mobile Technology-Based System to Improve Outcomes for People in Recovery for Alcohol Dependence

PubMed Central

Gustafson, David H.; Isham, Andrew; Baker, Timothy; Boyle, Michael G.; Levy, Michael

2011-01-01

Post treatment relapse to uncontrolled alcohol use is common. More cost-effective approaches are needed. We believe currently available communication technology can use existing models for relapse prevention to cost-effectively improve long-term relapse prevention. This paper describes: 1) research-based elements of alcohol related relapse prevention and how they can be encompassed in Self Determination Theory (SDT) and Marlatt’s Cognitive Behavioral Relapse Prevention Model, 2) how technology could help address the needs of people seeking recovery, 3) a technology-based prototype, organized around Self Determination Theory and Marlatt’s model and 4) how we are testing a system based on the ideas in this article and related ethical and operational considerations. PMID:21190410

Predicting phenolic acid absorption in Caco-2 cells: a theoretical permeability model and mechanistic study.

PubMed

Farrell, Tracy L; Poquet, Laure; Dew, Tristan P; Barber, Stuart; Williamson, Gary

2012-02-01

There is a considerable need to rationalize the membrane permeability and mechanism of transport for potential nutraceuticals. The aim of this investigation was to develop a theoretical permeability equation, based on a reported descriptive absorption model, enabling calculation of the transcellular component of absorption across Caco-2 monolayers. Published data for Caco-2 permeability of 30 drugs transported by the transcellular route were correlated with the descriptors 1-octanol/water distribution coefficient (log D, pH 7.4) and size, based on molecular mass. Nonlinear regression analysis was used to derive a set of model parameters a', β', and b' with an integrated molecular mass function. The new theoretical transcellular permeability (TTP) model obtained a good fit of the published data (R² = 0.93) and predicted reasonably well (R² = 0.86) the experimental apparent permeability coefficient (P(app)) for nine non-training set compounds reportedly transported by the transcellular route. For the first time, the TTP model was used to predict the absorption characteristics of six phenolic acids, and this original investigation was supported by in vitro Caco-2 cell mechanistic studies, which suggested that deviation of the P(app) value from the predicted transcellular permeability (P(app)(trans)) may be attributed to involvement of active uptake, efflux transporters, or paracellular flux.

Multispectroscopic and Theoretical Exploration of the Comparative Binding Aspects of Bioflavonoid Fisetin with Triple- and Double-Helical Forms of RNA.

PubMed

Bhuiya, Sutanwi; Haque, Lucy; Goswami, Rapti; Das, Suman

2017-12-14

The interactions of RNA triplex (U.A*U) and duplex (A.U) with naturally occurring flavonoid fisetin (FTN) have been examined at pH 7.0 using various spectroscopic, viscometric, and theoretical studies. Experimental observations showed that the ligand binds with both double- and triple-helical forms of RNA, although the binding affinity is greater for the triplex structure (5.94 × 10 6 M -1 ) compared to that for the duplex counterpart (1.0 × 10 5 M -1 ). Thermal melting experiments revealed that the Hoogsteen base-paired third strand of triplex was stabilized to a greater extent (∼14 °C) compared with the Watson-Crick base-paired second strand (∼4 °C) in the presence of FTN. From fluorimetric study, we observed that U.A*U and A.U primarily bind to the photoproduced tautomer of FTN in the excited state. Steady-state and time-resolved anisotropy measurements illustrate considerable modulations of the spectroscopic properties of the tautomeric FTN within the RNA environment. Viscometric, fluorescence quenching, and thermal melting studies all together support the mode of binding to be intercalation. Theoretical study explains the experimental absorption and emission (dual fluorescence) behavior of FTN along with the excited-state intramolecular proton transfer process.

Nonlinear Poisson Equation for Heterogeneous Media

PubMed Central

Hu, Langhua; Wei, Guo-Wei

2012-01-01

The Poisson equation is a widely accepted model for electrostatic analysis. However, the Poisson equation is derived based on electric polarizations in a linear, isotropic, and homogeneous dielectric medium. This article introduces a nonlinear Poisson equation to take into consideration of hyperpolarization effects due to intensive charges and possible nonlinear, anisotropic, and heterogeneous media. Variational principle is utilized to derive the nonlinear Poisson model from an electrostatic energy functional. To apply the proposed nonlinear Poisson equation for the solvation analysis, we also construct a nonpolar solvation energy functional based on the nonlinear Poisson equation by using the geometric measure theory. At a fixed temperature, the proposed nonlinear Poisson theory is extensively validated by the electrostatic analysis of the Kirkwood model and a set of 20 proteins, and the solvation analysis of a set of 17 small molecules whose experimental measurements are also available for a comparison. Moreover, the nonlinear Poisson equation is further applied to the solvation analysis of 21 compounds at different temperatures. Numerical results are compared to theoretical prediction, experimental measurements, and those obtained from other theoretical methods in the literature. A good agreement between our results and experimental data as well as theoretical results suggests that the proposed nonlinear Poisson model is a potentially useful model for electrostatic analysis involving hyperpolarization effects. PMID:22947937

Traduction et langues de specialite: Approches theoriques et considerations pedagogiques (Translation and Specialty Languages: Theoretical Approaches and Pedagogic Considerations).

ERIC Educational Resources Information Center

Guevel, Zelie, Ed.; Valentine, Egan, Ed.

Essays on the teaching of translation and on specialized translation, all in French, include: "Perspectives d'optimisation de la formation du traducteur: quelques reflexions" ("Perspectives on Optimization of Training of Translation Teachers: Some Reflections") (Egan Valentine); "L'enseignement de la revision…

Constructivist Viewpoints for School Teaching and Learning in Mathematics and Science. Research Report 131.

ERIC Educational Resources Information Center

Ahtee, Maija, Ed.; Pehkonen, Erkki, Ed.

This research report contains a fairly concise overview of the role of constructivism in the teaching of mathematics and science in Finland. Included papers have been grouped into three parts. The first part, "General Considerations," consists of the seven articles on theoretical considerations, social constructivism, teachers' and pupils'…

Investigating Cognitive Effort and Response Quality of Question Formats in Web Surveys Using Paradata

ERIC Educational Resources Information Center

Höhne, Jan Karem; Schlosser, Stephan; Krebs, Dagmar

2017-01-01

Measuring attitudes and opinions employing agree/disagree (A/D) questions is a common method in social research because it appears to be possible to measure different constructs with identical response scales. However, theoretical considerations suggest that A/D questions require a considerable cognitive processing. Item-specific (IS) questions,…

Developing a targeted, theory-informed implementation intervention using two theoretical frameworks to address health professional and organisational factors: a case study to improve the management of mild traumatic brain injury in the emergency department.

PubMed

Tavender, Emma J; Bosch, Marije; Gruen, Russell L; Green, Sally E; Michie, Susan; Brennan, Sue E; Francis, Jill J; Ponsford, Jennie L; Knott, Jonathan C; Meares, Sue; Smyth, Tracy; O'Connor, Denise A

2015-05-25

Despite the availability of evidence-based guidelines for the management of mild traumatic brain injury in the emergency department (ED), variations in practice exist. Interventions designed to implement recommended behaviours can reduce this variation. Using theory to inform intervention development is advocated; however, there is no consensus on how to select or apply theory. Integrative theoretical frameworks, based on syntheses of theories and theoretical constructs relevant to implementation, have the potential to assist in the intervention development process. This paper describes the process of applying two theoretical frameworks to investigate the factors influencing recommended behaviours and the choice of behaviour change techniques and modes of delivery for an implementation intervention. A stepped approach was followed: (i) identification of locally applicable and actionable evidence-based recommendations as targets for change, (ii) selection and use of two theoretical frameworks for identifying barriers to and enablers of change (Theoretical Domains Framework and Model of Diffusion of Innovations in Service Organisations) and (iii) identification and operationalisation of intervention components (behaviour change techniques and modes of delivery) to address the barriers and enhance the enablers, informed by theory, evidence and feasibility/acceptability considerations. We illustrate this process in relation to one recommendation, prospective assessment of post-traumatic amnesia (PTA) by ED staff using a validated tool. Four recommendations for managing mild traumatic brain injury were targeted with the intervention. The intervention targeting the PTA recommendation consisted of 14 behaviour change techniques and addressed 6 theoretical domains and 5 organisational domains. The mode of delivery was informed by six Cochrane reviews. It was delivered via five intervention components : (i) local stakeholder meetings, (ii) identification of local opinion leader teams, (iii) a train-the-trainer workshop for appointed local opinion leaders, (iv) local training workshops for delivery by trained local opinion leaders and (v) provision of tools and materials to prompt recommended behaviours. Two theoretical frameworks were used in a complementary manner to inform intervention development in managing mild traumatic brain injury in the ED. The effectiveness and cost-effectiveness of the developed intervention is being evaluated in a cluster randomised trial, part of the Neurotrauma Evidence Translation (NET) program.

Integrating psychological and neurobiological considerations regarding the development and maintenance of specific Internet-use disorders: An Interaction of Person-Affect-Cognition-Execution (I-PACE) model.

PubMed

Brand, Matthias; Young, Kimberly S; Laier, Christian; Wölfling, Klaus; Potenza, Marc N

2016-12-01

Within the last two decades, many studies have addressed the clinical phenomenon of Internet-use disorders, with a particular focus on Internet-gaming disorder. Based on previous theoretical considerations and empirical findings, we suggest an Interaction of Person-Affect-Cognition-Execution (I-PACE) model of specific Internet-use disorders. The I-PACE model is a theoretical framework for the processes underlying the development and maintenance of an addictive use of certain Internet applications or sites promoting gaming, gambling, pornography viewing, shopping, or communication. The model is composed as a process model. Specific Internet-use disorders are considered to be the consequence of interactions between predisposing factors, such as neurobiological and psychological constitutions, moderators, such as coping styles and Internet-related cognitive biases, and mediators, such as affective and cognitive responses to situational triggers in combination with reduced executive functioning. Conditioning processes may strengthen these associations within an addiction process. Although the hypotheses regarding the mechanisms underlying the development and maintenance of specific Internet-use disorders, summarized in the I-PACE model, must be further tested empirically, implications for treatment interventions are suggested. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Introduction of organic/hydro-organic matrices in inductively coupled plasma optical emission spectrometry and mass spectrometry: a tutorial review. Part I. Theoretical considerations.

PubMed

Leclercq, Amélie; Nonell, Anthony; Todolí Torró, José Luis; Bresson, Carole; Vio, Laurent; Vercouter, Thomas; Chartier, Frédéric

2015-07-23

Due to their outstanding analytical performances, inductively coupled plasma optical emission spectrometry (ICP-OES) and mass spectrometry (ICP-MS) are widely used for multi-elemental measurements and also for isotopic characterization in the case of ICP-MS. While most studies are carried out in aqueous matrices, applications involving organic/hydro-organic matrices become increasingly widespread. This kind of matrices is introduced in ICP based instruments when classical "matrix removal" approaches such as acid digestion or extraction procedures cannot be implemented. Due to the physico-chemical properties of organic/hydro-organic matrices and their associated effects on instrumentation and analytical performances, their introduction into ICP sources is particularly challenging and has become a full topic. In this framework, numerous theoretical and phenomenological studies of these effects have been performed in the past, mainly by ICP-OES, while recent literature is more focused on applications and associated instrumental developments. This tutorial review, divided in two parts, explores the rich literature related to the introduction of organic/hydro-organic matrices in ICP-OES and ICP-MS. The present Part I, provides theoretical considerations in connection with the physico-chemical properties of organic/hydro-organic matrices, in order to better understand the induced phenomena. This focal point is divided in four chapters highlighting: (i) the impact of organic/hydro-organic matrices from aerosol generation to atomization/excitation/ionization processes; (ii) the production of carbon molecular constituents and their spatial distribution in the plasma with respect to analytes repartition; (iii) the subsequent modifications of plasma fundamental properties; and (iv) the resulting spectroscopic and non spectroscopic interferences. This first part of this tutorial review is addressed either to beginners or to more experienced scientists who are interested in the analysis of organic/hydro-organic matrices by ICP sources and would like to consider the theoretical background of effects induced by such matrices. The second part of this tutorial review will be dedicated to more practical consideration on instrumentation, such as adapted introductions devices, as well as instrumental and operating parameters optimization. The analytical strategies for elemental quantification in such matrices will also be addressed. Copyright © 2015 Elsevier B.V. All rights reserved.

Mental health interventions for traumatized asylum seekers and refugees: What do we know about their efficacy?

PubMed

Slobodin, Ortal; de Jong, Joop T V M

2015-02-01

The prevalence of trauma-related problems among refugees and asylum seekers is extremely high due to adverse experiences associated with forced migration. Although the literature presents a considerable number of guidelines and theoretical frameworks for working with traumatized refugees and asylum seekers, the efficacy, feasibility and applicability of these interventions have little empirical evidence. The purpose of this article is to critically review the literature to provide a rationale for developing culturally sensitive, evidence-based interventions for refugees and asylum seekers. A literature review integrating research findings on interventions designed especially for traumatized asylum seekers and refugees was conducted. Retained studies had to use some quantitative measurements of post-traumatic stress and to have pre- and post-measurements to evaluate the efficacy of the intervention. Studies included in this review cover a wide variety of interventions, including trauma-focused interventions, group therapy, multidisciplinary interventions and pharmacological treatments. The majority of studies with traumatized refugees and asylum seekers reported positive outcomes of the intervention in reducing trauma-related symptoms. There is evidence to support the suitability of cognitive-behavioral therapy (CBT) and narrative exposure therapy (NET) in certain populations of refugees. Other intervention studies are limited by methodological considerations, such as lack of randomization, absence of control group and small samples. This review has again highlighted the shortage of guiding frameworks available to investigators and clinicians who are interested in tailoring interventions to work with refugees and asylum seekers. Theoretical, ethical and methodological considerations for future research are discussed. © The Author(s) 2014.

What can we learn from Einstein and Arrhenius about the optimal flow of our blood?

PubMed

Schuster, Stefan; Stark, Heiko

2014-01-01

The oxygen flow in humans and other higher animals depends on the erythrocyte-to-blood volume ratio, the hematocrit. Since it is physiologically favourable when the flow of oxygen transport is maximum it can be assumed that this situation has been achieved during evolution. If the hematocrit was too low, too few erythrocytes could transport oxygen. If it was too high, the blood would be very viscous, so that oxygen supply would again be reduced. The theoretical optimal hematocrit can be calculated by considering the dependence of blood viscosity on the hematocrit. Different approaches to expressing this dependence have been proposed in the literature. Here, we discuss early approaches in hydrodynamics proposed by Einstein and Arrhenius and show that especially the Arrhenius equation is very appropriate for this purpose. We show that despite considerable simplifications such as neglecting the deformation, orientation and aggregation of erythrocytes, realistic hematocrit values of about 40% can be derived based on optimality considerations. Also the prediction that the ratio between the viscosities of the blood and blood plasma at high shear rates nearly equals Euler's constant (2.718) is in good agreement with observed values. Finally, we discuss possible extensions of the theory. For example, we derive the theoretical optimal hematocrit for persevering divers among marine mammals to be 65%, in excellent agreement with the values observed in several species. These considerations are very important for human and animal physiology since oxygen transport is an important factor for medicine and physical performance. © 2013 Elsevier B.V. All rights reserved.

The Intuitive Physics of the Equilibrium of the Lever and of the Hydraulic Pressures: Implications for the Teaching of Elementary Physics

ERIC Educational Resources Information Center

Masin, Sergio Cesare; Crivellaro, Francesco; Varotto, Diego

2014-01-01

The research field of intuitive physics focuses on discrepancies between theoretical and intuitive physical knowledge. Consideration of these discrepancies can help in the teaching of elementary physics. However, evidence shows that theoretical and intuitive physical knowledge may also be congruent. Physics teaching could further benefit from…

Theoretical Perspectives of Male Sexual Abuse: Conceptualization of a Case Study

ERIC Educational Resources Information Center

Diamanduros, Terry; Cosentino, Clare E.; Tysinger, P. Dawn; Tysinger, Jeffrey A.

2012-01-01

The purpose of this article is to demonstrate the traumatic impact that sexual abuse can have on a young male's development by addressing mediating dispositions that can render a child vulnerable to the effects of sexual abuse. Consideration is given to three different theoretical perspectives that are not exclusive to male victims but shed light…

Low noise SQUIDs

NASA Astrophysics Data System (ADS)

de Waal, V. J.

1983-02-01

The present investigation deals with the design, fabrication, and limitations of very sensitive SQUID (Superconducting Quantum Interference Device) magnetometers. The SQUID magnetometer is based on a utilization of the Josephson effect. A description of the theoretical background is provided, and high performance DC SQUIDs with submicron niobium Josephson junctions are discussed, taking into account design considerations, fabrication, junction characterization, the performance of the SQUID and input coil, and the gradiometer performance. The simulation and optimization of a DC SQUID with finite capacitance is considered, giving attention to the implementation of a simulation procedure on a hybrid computer.

Utility of the Electrocardiogram in Drug Overdose and Poisoning: Theoretical Considerations and Clinical Implications

PubMed Central

Yates, Christopher; Manini, Alex F

2012-01-01

The ECG is a rapidly available clinical tool that can help clinicians manage poisoned patients. Specific myocardial effects of cardiotoxic drugs have well-described electrocardiographic manifestations. In the practice of clinical toxicology, classic ECG changes may hint at blockade of ion channels, alterations of adrenergic tone, or dysfunctional metabolic activity of the myocardium. This review will offer a structured approach to ECG interpretation in poisoned patients with a focus on clinical implications and ECG-based management recommendations in the initial evaluation of patients with acute cardiotoxicity. PMID:22708912

Implementation of Gravity Model to Estimation of Transportation Market Shares

NASA Astrophysics Data System (ADS)

Krata, Przemysław

2010-03-01

The theoretical consideration presented in the paper is inspired by market gravity models, as an interesting attitude towards operations research on a market. The transportation market issues are emphasized. The mathematical model of relations, taking place between transportation companies and their customers on the market, which is applied in the course of the research is based on continuous functions characteristics. This attitude enables the use of the field theory notions. The resultant vector-type utility function facilitates obtaining of competitive advantage areas for all transportation companies located on the considered transportation market.

Efficiency-enhanced photon sieve using Gaussian/overlapping distribution of pinholes

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

Sabatyan, A.; Mirzaie, S.

2011-04-10

A class of photon sieve is introduced whose structure is based on the overlapping pinholes in the innermost zones. This kind of distribution is produced by, for example, a particular form of Gaussian function. The focusing property of the proposed model was examined theoretically and experimentally. It is shown that under He-Ne laser and white light illumination, the focal spot size of this novel structure has considerably smaller FWHM than a photon sieve with randomly distributed pinholes and a Fresnel zone plate. In addition, secondary maxima have been suppressed effectively.

A framework for comparing different image segmentation methods and its use in studying equivalences between level set and fuzzy connectedness frameworks

PubMed Central

Ciesielski, Krzysztof Chris; Udupa, Jayaram K.

2011-01-01

In the current vast image segmentation literature, there seems to be considerable redundancy among algorithms, while there is a serious lack of methods that would allow their theoretical comparison to establish their similarity, equivalence, or distinctness. In this paper, we make an attempt to fill this gap. To accomplish this goal, we argue that: (1) every digital segmentation algorithm A should have a well defined continuous counterpart MA, referred to as its model, which constitutes an asymptotic of A when image resolution goes to infinity; (2) the equality of two such models MA and MA′ establishes a theoretical (asymptotic) equivalence of their digital counterparts A and A′. Such a comparison is of full theoretical value only when, for each involved algorithm A, its model MA is proved to be an asymptotic of A. So far, such proofs do not appear anywhere in the literature, even in the case of algorithms introduced as digitizations of continuous models, like level set segmentation algorithms. The main goal of this article is to explore a line of investigation for formally pairing the digital segmentation algorithms with their asymptotic models, justifying such relations with mathematical proofs, and using the results to compare the segmentation algorithms in this general theoretical framework. As a first step towards this general goal, we prove here that the gradient based thresholding model M∇ is the asymptotic for the fuzzy connectedness Udupa and Samarasekera segmentation algorithm used with gradient based affinity A∇. We also argue that, in a sense, M∇ is the asymptotic for the original front propagation level set algorithm of Malladi, Sethian, and Vemuri, thus establishing a theoretical equivalence between these two specific algorithms. Experimental evidence of this last equivalence is also provided. PMID:21442014

Explicit and implicit assessment of gender roles.

PubMed

Fernández, Juan; Quiroga, M Ángeles; Escorial, Sergio; Privado, Jesús

2014-05-01

Gender roles have been assessed by explicit measures and, recently, by implicit measures. In the former case, the theoretical assumptions have been questioned by empirical results. To solve this contradiction, we carried out two concatenated studies based on a relatively well-founded theoretical and empirical approach. The first study was designed to obtain a sample of genderized activities of the domestic sphere by means of an explicit assessment. Forty-two raters (22 women and 20 men, balanced on age, sex, and level of education) took part as raters. In the second study, an implicit assessment of gender roles was carried out, focusing on the response time given to the sample activities obtained from the first study. A total of 164 adults (90 women and 74 men, mean age = 43), with experience in living with a partner and balanced on age, sex, and level of education, participated. Taken together, results show that explicit and implicit assessment converge. The current social reality shows that there is still no equity in some gender roles in the domestic sphere. These consistent results show considerable theoretical and empirical robustness, due to the double implicit and explicit assessment.

Coupled microrings data buffer using fast light

NASA Astrophysics Data System (ADS)

Scheuer, Jacob; Shahriar, Selim

2013-03-01

We present a theoretical study of a trap-door optical buffer based on a coupled microrings add/drop filter (ADF) utilizing the white light cavity (WLC). The buffer "trap-door" can be opened and closed by tuning the resonances of the microrings comprising the ADF and trap/release optical pulses. We show that the WLC based ADF yields a maximally flat filter which exhibits superior performances in terms of bandwidth and flatness compared to previous design approaches. We also present a realistic, Silicon-over-Insulator based, design and performance analysis taking into consideration the realistic properties and limitations of the materials and the fabrication process, leading to delays exceeding 850ps for 80GHz bandwidth, and a corresponding delay-bandwidth product of approximately 70.

Resonance-Based Sparse Signal Decomposition and its Application in Mechanical Fault Diagnosis: A Review.

PubMed

Huang, Wentao; Sun, Hongjian; Wang, Weijie

2017-06-03

Mechanical equipment is the heart of industry. For this reason, mechanical fault diagnosis has drawn considerable attention. In terms of the rich information hidden in fault vibration signals, the processing and analysis techniques of vibration signals have become a crucial research issue in the field of mechanical fault diagnosis. Based on the theory of sparse decomposition, Selesnick proposed a novel nonlinear signal processing method: resonance-based sparse signal decomposition (RSSD). Since being put forward, RSSD has become widely recognized, and many RSSD-based methods have been developed to guide mechanical fault diagnosis. This paper attempts to summarize and review the theoretical developments and application advances of RSSD in mechanical fault diagnosis, and to provide a more comprehensive reference for those interested in RSSD and mechanical fault diagnosis. Followed by a brief introduction of RSSD's theoretical foundation, based on different optimization directions, applications of RSSD in mechanical fault diagnosis are categorized into five aspects: original RSSD, parameter optimized RSSD, subband optimized RSSD, integrated optimized RSSD, and RSSD combined with other methods. On this basis, outstanding issues in current RSSD study are also pointed out, as well as corresponding instructional solutions. We hope this review will provide an insightful reference for researchers and readers who are interested in RSSD and mechanical fault diagnosis.

Resonance-Based Sparse Signal Decomposition and Its Application in Mechanical Fault Diagnosis: A Review

PubMed Central

Huang, Wentao; Sun, Hongjian; Wang, Weijie

2017-01-01

Mechanical equipment is the heart of industry. For this reason, mechanical fault diagnosis has drawn considerable attention. In terms of the rich information hidden in fault vibration signals, the processing and analysis techniques of vibration signals have become a crucial research issue in the field of mechanical fault diagnosis. Based on the theory of sparse decomposition, Selesnick proposed a novel nonlinear signal processing method: resonance-based sparse signal decomposition (RSSD). Since being put forward, RSSD has become widely recognized, and many RSSD-based methods have been developed to guide mechanical fault diagnosis. This paper attempts to summarize and review the theoretical developments and application advances of RSSD in mechanical fault diagnosis, and to provide a more comprehensive reference for those interested in RSSD and mechanical fault diagnosis. Followed by a brief introduction of RSSD’s theoretical foundation, based on different optimization directions, applications of RSSD in mechanical fault diagnosis are categorized into five aspects: original RSSD, parameter optimized RSSD, subband optimized RSSD, integrated optimized RSSD, and RSSD combined with other methods. On this basis, outstanding issues in current RSSD study are also pointed out, as well as corresponding instructional solutions. We hope this review will provide an insightful reference for researchers and readers who are interested in RSSD and mechanical fault diagnosis. PMID:28587198

Sexual Grooming of Children: Review of Literature and Theoretical Considerations

ERIC Educational Resources Information Center

Craven, Samantha; Brown, Sarah; Gilchrist, Elizabeth

2006-01-01

The current review aims to outline the existing understanding of sexual grooming. Issues of poor definition, the adoption of the term "grooming" and the prevalence of sexual grooming will be discussed. Consideration will be given to how prominent theories of child sexual abuse often neglect sexual grooming. This will be followed by a detailed…

Molecular Spintronics: Theory of Spin-Dependent Electron Transport in Fe/BDT/Fe Molecular Wire Systems

NASA Astrophysics Data System (ADS)

Dalgleish, Hugh; Kirczenow, George

2004-03-01

Metal/Molecule/Metal junction systems forming molecular wires are currently the focus of intense study. Recently, spin-dependent electron transport in molecular wires with magnetic Ni electrodes has been studied theoretically, and spin-valve effects have been predicted.* Here we explore theoretically another magnetic molecular wire system, namely, ferromagnetic Fe nano-contacts bridged with 1,4-benzene-dithiolate (BDT). We estimate the essential structural and electronic parameters for this system based on ab initio density functional calculations (DFT) for some simple model systems involving thiol groups and Fe clusters as well as semi-empirical considerations and the known electronic structure of bulk Fe. We then use Lippmann-Schwinger and Green's function techniques together with the Landauer formalism to study spin-dependent transport. *E. G. Emberly and G. Kirczenow, Chem. Phys. 281, 311 (2002); R. Pati, L. Senapati, P.M. Ajayan and S.K. Nayak, Phys. Rev. B68, 100407 (2003).

Theory of high-resolution tunneling spin transport on a magnetic skyrmion

NASA Astrophysics Data System (ADS)

Palotás, Krisztián; Rózsa, Levente; Szunyogh, László

2018-05-01

Tunneling spin transport characteristics of a magnetic skyrmion are described theoretically in magnetic scanning tunneling microscopy (STM). The spin-polarized charge current in STM (SP-STM) and tunneling spin transport vector quantities, the longitudinal spin current and the spin transfer torque, are calculated in high spatial resolution within the same theoretical framework. A connection between the conventional charge current SP-STM image contrasts and the magnitudes of the spin transport vectors is demonstrated that enables the estimation of tunneling spin transport properties based on experimentally measured SP-STM images. A considerable tunability of the spin transport vectors by the involved spin polarizations is also highlighted. These possibilities and the combined theory of tunneling charge and vector spin transport pave the way for gaining deep insight into electric-current-induced tunneling spin transport properties in SP-STM and to the related dynamics of complex magnetic textures at surfaces.

Community stakeholder responses to advocacy advertising

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

Miller, B.; Sinclair, J.

Focus group research was used to examine how community stakeholders, a group with local industry experience, responded to coal industry advocacy messages. The stakeholders expressed beliefs about both the advertiser and the coal industry, and while their knowledge led to critical consideration of the industry campaign, they also expressed a desire to identify with positive messages about their community. Applying a postpositivist research perspective, a new model is introduced to integrate these beliefs in terms of advertiser trust and industry accountability under the existing theoretical framework of persuasion knowledge. Agent and topic knowledge are combined in this model based onmore » responses to the industry advocacy campaign. In doing so, this study integrates a priori theory within a new context, extending the current theoretical framework to include an understanding of how community stakeholders - a common target for marketplace advocacy - interpret industry messages.« less

Constraints on axion inflation from the weak gravity conjecture

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

Rudelius, Tom, E-mail: rudelius@physics.harvard.edu

2015-09-01

We derive constraints facing models of axion inflation based on decay constant alignment from a string-theoretic and quantum gravitational perspective. In particular, we investigate the prospects for alignment and 'anti-alignment' of C{sub 4} axion decay constants in type IIB string theory, deriving a strict no-go result in the latter case. We discuss the relationship of axion decay constants to the weak gravity conjecture and demonstrate agreement between our string-theoretic constraints and those coming from the 'generalized' weak gravity conjecture. Finally, we consider a particular model of decay constant alignment in which the potential of C{sub 4} axions in type IIBmore » compactifications on a Calabi-Yau three-fold is dominated by contributions from D7-branes, pointing out that this model evades some of the challenges derived earlier in our paper but is highly constrained by other geometric considerations.« less

Constraints on axion inflation from the weak gravity conjecture

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

Rudelius, Tom

2015-09-08

We derive constraints facing models of axion inflation based on decay constant alignment from a string-theoretic and quantum gravitational perspective. In particular, we investigate the prospects for alignment and ‘anti-alignment’ of C{sub 4} axion decay constants in type IIB string theory, deriving a strict no-go result in the latter case. We discuss the relationship of axion decay constants to the weak gravity conjecture and demonstrate agreement between our string-theoretic constraints and those coming from the ‘generalized’ weak gravity conjecture. Finally, we consider a particular model of decay constant alignment in which the potential of C{sub 4} axions in type IIBmore » compactifications on a Calabi-Yau three-fold is dominated by contributions from D7-branes, pointing out that this model evades some of the challenges derived earlier in our paper but is highly constrained by other geometric considerations.« less

Microelectrode generator-collector systems for electrolytic titration: theoretical and practical considerations.

PubMed

Bell, Christopher G; Seelanan, Parinya; O'Hare, Danny

2017-10-23

Electochemical generator-collector systems, where one electrode is used to generate a reagent, have a potentially large field of application in sensing and measurement. We present a new theoretical description for coplanar microelectrode disc-disc systems where the collector is passive (such as a potentiometric sensor) and the generator is operating at constant flux. This solution is then used to develop a leading order solution for such a system where the reagent reacts reversibly in solution, such as in acid-base titration, where a hydrogen ion flux is generated by electrolysis of water. The principal novel result of the theory is that such devices are constrained by a maximum reagent flux. The hydrogen ion concentration at the collector will only reflect the buffer capacity of the bulk solution if this constraint is met. Both mathematical solutions are evaluated with several microfabricated devices and reasonable agreement with theory is demonstrated.

Reply to comment by Fred L. Ogden et al. on "Beyond the SCS-CN method: A theoretical framework for spatially lumped rainfall-runoff response"

NASA Astrophysics Data System (ADS)

Bartlett, M. S.; Parolari, A. J.; McDonnell, J. J.; Porporato, A.

2017-07-01

Though Ogden et al. list several shortcomings of the original SCS-CN method, fit for purpose is a key consideration in hydrological modelling, as shown by the adoption of SCS-CN method in many design standards. The theoretical framework of Bartlett et al. [2016a] reveals a family of semidistributed models, of which the SCS-CN method is just one member. Other members include event-based versions of the Variable Infiltration Capacity (VIC) model and TOPMODEL. This general model allows us to move beyond the limitations of the original SCS-CN method under different rainfall-runoff mechanisms and distributions for soil and rainfall variability. Future research should link this general model approach to different hydrogeographic settings, in line with the call for action proposed by Ogden et al.

Heterogeneity among violence-exposed women: applying person-oriented research methods.

PubMed

Nurius, Paula S; Macy, Rebecca J

2008-03-01

Variability of experience and outcomes among violence-exposed people pose considerable challenges toward developing effective prevention and treatment protocols. To address these needs, the authors present an approach to research and a class of methodologies referred to as person oriented. Person-oriented tools support assessment of meaningful patterns among people that distinguish one group from another, subgroups for whom different interventions are indicated. The authors review the conceptual base of person-oriented methods, outline their distinction from more familiar variable-oriented methods, present descriptions of selected methods as well as empirical applications of person-oriented methods germane to violence exposure, and conclude with discussion of implications for future research and translation between research and practice. The authors focus on violence against women as a population, drawing on stress and coping theory as a theoretical framework. However, person-oriented methods hold utility for investigating diversity among violence-exposed people's experiences and needs across populations and theoretical foundations.

Corrective Feedback in L2 Writing: Theoretical Perspectives, Empirical Insights, and Future Directions

ERIC Educational Resources Information Center

Van Beuningen, Catherine

2010-01-01

The role of (written) corrective feedback (CF) in the process of acquiring a second language (L2) has been an issue of considerable controversy among theorists and researchers alike. Although CF is a widely applied pedagogical tool and its use finds support in SLA theory, practical and theoretical objections to its usefulness have been raised…

The Importance of Emotion in Theories of Motivation: Empirical, Methodological, and Theoretical Considerations from a Goal Theory Perspective

ERIC Educational Resources Information Center

Turner, Julianne C.; Meyer, Debra K.; Schweinle, Amy

2003-01-01

Despite its importance to educational psychology, prominent theories of motivation have mostly ignored emotion. In this paper, we review theoretical conceptions of the relation between motivation and emotion and discuss the role of emotion in understanding student motivation in classrooms. We demonstrate that emotion is one of the best indicators…

Using the theoretical domains framework to guide the development of a self-management program for individuals with spinal cord injury: Results from a national stakeholder advisory group.

PubMed

Munce, Sarah E P; Allin, Sonya; Wolfe, Dalton L; Anzai, Karen; Linassi, Gary; Noonan, Vanessa K; Jaglal, Susan B

2017-11-01

To determine the implementation considerations for a targeted self-management program for individuals with spinal cord injury (SCI) from the perspective of a national stakeholder advisory group using the Theoretical Domains Framework (TDF) as a guide. Qualitative descriptive approach. Two focus groups held at the 6 th National Spinal Cord Injury Conference (October 2-4 th , 2014) in Toronto, Ontario, Canada. A total of 25 stakeholders from across Canada participated in focus groups or "brainstorming sessions". The stakeholders included 5 clinicians, 14 researchers, 3 policy makers, and 3 individuals with SCI. Not applicable. Not applicable. All 14 theoretical domains were identified in the brainstorming sessions. No new themes or domains were identified. The need to consider the theoretical domains of Knowledge, Skills, Reinforcement, Intentions, Goals (e.g. the readiness of the individual with SCI), Environmental Context and Resources (e.g. considerations for governance and ownership of the program and a business model for sustainability), as well as Social Influences (e.g. issues of privacy and security in the context of on-line delivery) was identified. The current study provides complementary results to our previous series of studies on the implementation considerations for the development of a targeted self-management program for individuals with SCI by emphasizing the health care professional/health policy perspective. It is anticipated that such a program could not only reduce secondary complications and subsequent inappropriate health care use but it may also improve the quality of life for individuals with SCI and their caregivers.

Design factors and considerations for a time-based flight management system

NASA Technical Reports Server (NTRS)

Vicroy, D. D.; Williams, D. H.; Sorensen, J. A.

1986-01-01

Recent NASA Langley Research Center research to develop a technology data base from which an advanced Flight Management System (FMS) design might evolve is reviewed. In particular, the generation of fixed range cruise/descent reference trajectories which meet predefined end conditions of altitude, speed, and time is addressed. Results on the design and theoretical basis of the trajectory generation algorithm are presented, followed by a brief discussion of a series of studies that are being conducted to determine the accuracy requirements of the aircraft and weather models resident in the trajectory generation algorithm. Finally, studies to investigate the interface requirements between the pilot and an advanced FMS are considered.

A four-component Fock-space coupled cluster investigation of the HM(CO)5, (M = Mn, Re) photoelectron spectra

NASA Astrophysics Data System (ADS)

Nikoobakht, Behnam; Siebert, Max; Pernpointner, Markus

2015-11-01

In this work, we readdress the photoelectron spectra of the HM(CO)5, (M=Mn, Re) carbonyl complexes by applying four-component Fock-space coupled cluster (FSCC) methods for their calculation in order to extend earlier studies based on less demanding approaches. The final-state characterisation was based on group theoretical considerations of the contributing orbitals and allowed for an unambiguous assignment. Energy level diagrams show the effect of spin-orbit (SO) coupling starting from scalar relativistic results and for the heavy representative HRe(CO)5 nonadditivity effects of SO and electron correlation can be observed requiring a consistent treatment of both contributions.

An Efficient Estimator for Moving Target Localization Using Multi-Station Dual-Frequency Radars.

PubMed

Huang, Jiyan; Zhang, Ying; Luo, Shan

2017-12-15

Localization of a moving target in a dual-frequency radars system has now gained considerable attention. The noncoherent localization approach based on a least squares (LS) estimator has been addressed in the literature. Compared with the LS method, a novel localization method based on a two-step weighted least squares estimator is proposed to increase positioning accuracy for a multi-station dual-frequency radars system in this paper. The effects of signal noise ratio and the number of samples on the performance of range estimation are also analyzed in the paper. Furthermore, both the theoretical variance and Cramer-Rao lower bound (CRLB) are derived. The simulation results verified the proposed method.

An Efficient Estimator for Moving Target Localization Using Multi-Station Dual-Frequency Radars

PubMed Central

Zhang, Ying; Luo, Shan

2017-01-01

Localization of a moving target in a dual-frequency radars system has now gained considerable attention. The noncoherent localization approach based on a least squares (LS) estimator has been addressed in the literature. Compared with the LS method, a novel localization method based on a two-step weighted least squares estimator is proposed to increase positioning accuracy for a multi-station dual-frequency radars system in this paper. The effects of signal noise ratio and the number of samples on the performance of range estimation are also analyzed in the paper. Furthermore, both the theoretical variance and Cramer–Rao lower bound (CRLB) are derived. The simulation results verified the proposed method. PMID:29244727

A new scenario-based approach to damage detection using operational modal parameter estimates

NASA Astrophysics Data System (ADS)

Hansen, J. B.; Brincker, R.; López-Aenlle, M.; Overgaard, C. F.; Kloborg, K.

2017-09-01

In this paper a vibration-based damage localization and quantification method, based on natural frequencies and mode shapes, is presented. The proposed technique is inspired by a damage assessment methodology based solely on the sensitivity of mass-normalized experimental determined mode shapes. The present method differs by being based on modal data extracted by means of Operational Modal Analysis (OMA) combined with a reasonable Finite Element (FE) representation of the test structure and implemented in a scenario-based framework. Besides a review of the basic methodology this paper addresses fundamental theoretical as well as practical considerations which are crucial to the applicability of a given vibration-based damage assessment configuration. Lastly, the technique is demonstrated on an experimental test case using automated OMA. Both the numerical study as well as the experimental test case presented in this paper are restricted to perturbations concerning mass change.

Theoretical study of NMR, infrared and Raman spectra on triple-decker phthalocyanines

NASA Astrophysics Data System (ADS)

Suzuki, Atsushi; Oku, Takeo

2016-02-01

Electronic structures and magnetic properties of multi-decker phthalocyanines were studied by theoretical calculation. Electronic structures, excited processes at multi-states, isotropic chemical shifts of 13C, 14N and 1H-nuclear magnetic resonance (NMR), principle V-tensor in electronic field gradient (EFG) tensor and asymmetry parameters (η), vibration mode in infrared (IR) and Raman spectra of triple-decker phthalocyanines were calculated by density functional theory (DFT) and time-dependent DFT using B3LYP as basis function. Electron density distribution was delocalized on the phthalocyanine rings with electron static potential. Considerable separation of chemical shifts in 13C, 14N and 1H-NMR was originated from nuclear spin interaction between nitrogen and carbon atoms, nuclear quadrupole interaction based on EFG and η of central metal under crystal field. Calculated optical absorption at multi-excited process was derived from overlapping π-orbital on the phthalocyanine rings. The vibration modes in IR and Raman spectra were based on in-plane deformation and stretching vibrations of metal-ligand coordination bond on the deformed structure.

Net alkalinity and net acidity 1: Theoretical considerations

USGS Publications Warehouse

Kirby, C.S.; Cravotta, C.A.

2005-01-01

Net acidity and net alkalinity are widely used, poorly defined, and commonly misunderstood parameters for the characterization of mine drainage. The authors explain theoretical expressions of 3 types of alkalinity (caustic, phenolphthalein, and total) and acidity (mineral, CO2, and total). Except for rarely-invoked negative alkalinity, theoretically defined total alkalinity is closely analogous to measured alkalinity and presents few practical interpretation problems. Theoretically defined "CO 2-acidity" is closely related to most standard titration methods with an endpoint pH of 8.3 used for determining acidity in mine drainage, but it is unfortunately named because CO2 is intentionally driven off during titration of mine-drainage samples. Using the proton condition/mass- action approach and employing graphs to illustrate speciation with changes in pH, the authors explore the concept of principal components and how to assign acidity contributions to aqueous species commonly present in mine drainage. Acidity is defined in mine drainage based on aqueous speciation at the sample pH and on the capacity of these species to undergo hydrolysis to pH 8.3. Application of this definition shows that the computed acidity in mg L -1 as CaCO3 (based on pH and analytical concentrations of dissolved FeII, FeIII, Mn, and Al in mg L -1):aciditycalculated=50{1000(10-pH)+[2(FeII)+3(FeIII)]/56+2(Mn)/ 55+3(Al)/27}underestimates contributions from HSO4- and H+, but overestimates the acidity due to Fe3+ and Al3+. However, these errors tend to approximately cancel each other. It is demonstrated that "net alkalinity" is a valid mathematical construction based on theoretical definitions of alkalinity and acidity. Further, it is shown that, for most mine-drainage solutions, a useful net alkalinity value can be derived from: (1) alkalinity and acidity values based on aqueous speciation, (2) measured alkalinity minus calculated acidity, or (3) taking the negative of the value obtained in a standard method "hot peroxide" acidity titration, provided that labs report negative values. The authors recommend the third approach; i.e., net alkalinity = -Hot Acidity. ?? 2005 Elsevier Ltd. All rights reserved.

Theoretical Calculations on Sediment Transport on Titan, and the Possible Production of Streamlined Forms

NASA Technical Reports Server (NTRS)

Burr, D. M.; Emery, J. P.; Lorenz, R. D.

2005-01-01

The Cassini Imaging Science System (ISS) has been returning images of Titan, along with other Saturnian satellites. Images taken through the 938 nm methane window see down to Titan's surface. One of the purposes of the Cassini mission is to investigate possible fluid cycling on Titan. Lemniscate features shown recently and radar evidence of surface flow prompted us to consider theoretically the creation by methane fluid flow of streamlined forms on Titan. This follows work by other groups in theoretical consideration of fluid motion on Titan's surface.

Group theoretical approach to the Dirac operator on S 2

NASA Astrophysics Data System (ADS)

Gutiérrez, Sergio; Huet, Idrish

2018-04-01

In this revision we outline the group theoretical approach to formulate and solve the eigenvalue problem of the Dirac operator on the round 2-sphere conceived as the right coset S 2 = SU(2)/U(1). Starting from general symmetry considerations we illustrate the formulation of the Dirac operator through left action or right action differential operators, whose properties on a right coset are quite different. The construction of the spinor space and the solution of the spectral problem using group theoretical methods is also presented.

Measuring Global Disease with Wikipedia: Success, Failure, and a Research Agenda

PubMed Central

Priedhorsky, Reid; Osthus, Dave; Daughton, Ashlynn R.; Moran, Kelly R.; Generous, Nicholas; Fairchild, Geoffrey; Deshpande, Alina; Del Valle, Sara Y.

2017-01-01

Effective disease monitoring provides a foundation for effective public health systems. This has historically been accomplished with patient contact and bureaucratic aggregation, which tends to be slow and expensive. Recent internet-based approaches promise to be real-time and cheap, with few parameters. However, the question of when and how these approaches work remains open. We addressed this question using Wikipedia access logs and category links. Our experiments, replicable and extensible using our open source code and data, test the effect of semantic article filtering, amount of training data, forecast horizon, and model staleness by comparing across 6 diseases and 4 countries using thousands of individual models. We found that our minimal-configuration, language-agnostic article selection process based on semantic relatedness is effective for improving predictions, and that our approach is relatively insensitive to the amount and age of training data. We also found, in contrast to prior work, very little forecasting value, and we argue that this is consistent with theoretical considerations about the nature of forecasting. These mixed results lead us to propose that the currently observational field of internet-based disease surveillance must pivot to include theoretical models of information flow as well as controlled experiments based on simulations of disease. PMID:28782059

Rethinking the intensive care environment: considering nature in nursing practice.

PubMed

Minton, Claire; Batten, Lesley

2016-01-01

With consideration of an environmental concept, this paper explores evidence related to the negative impacts of the intensive care unit environment on patient outcomes and explores the potential counteracting benefits of 'nature-based' nursing interventions as a way to improve care outcomes. The impact of the environment in which a patient is nursed has long been recognised as one determinant in patient outcomes. Whilst the contemporary intensive care unit environment contains many features that support the provision of the intensive therapies the patient requires, it can also be detrimental, especially for long-stay patients. This narrative review considers theoretical and evidence-based literature that supports the adoption of nature-based nursing interventions in intensive care units. Research and theoretical literature from a diverse range of disciplines including nursing, medicine, psychology, architecture and environmental science were considered in relation to patient outcomes and intensive care nursing practice. There are many nature-based interventions that intensive care unit nurses can implement into their nursing practice to counteract environmental stressors. These interventions can also improve the environment for patients' families and nurses. Intensive care unit nurses must actively consider and manage the environment in which nursing occurs to facilitate the best patient outcomes. © 2015 John Wiley & Sons Ltd.

Theoretical Limits of Energy Density in Silicon-Carbon Composite Anode Based Lithium Ion Batteries

PubMed Central

Dash, Ranjan; Pannala, Sreekanth

2016-01-01

Silicon (Si) is under consideration as a potential next-generation anode material for the lithium ion battery (LIB). Experimental reports of up to 40% increase in energy density of Si anode based LIBs (Si-LIBs) have been reported in literature. However, this increase in energy density is achieved when the Si-LIB is allowed to swell (volumetrically expand) more than graphite based LIB (graphite-LIB) and beyond practical limits. The volume expansion of LIB electrodes should be negligible for applications such as automotive or mobile devices. We determine the theoretical bounds of Si composition in a Si–carbon composite (SCC) based anode to maximize the volumetric energy density of a LIB by constraining the external dimensions of the anode during charging. The porosity of the SCC anode is adjusted to accommodate the volume expansion during lithiation. The calculated threshold value of Si was then used to determine the possible volumetric energy densities of LIBs with SCC anode (SCC-LIBs) and the potential improvement over graphite-LIBs. The level of improvement in volumetric and gravimetric energy density of SCC-LIBs with constrained volume is predicted to be less than 10% to ensure the battery has similar power characteristics of graphite-LIBs. PMID:27311811

Measuring Global Disease with Wikipedia: Success, Failure, and a Research Agenda.

PubMed

Priedhorsky, Reid; Osthus, Dave; Daughton, Ashlynn R; Moran, Kelly R; Generous, Nicholas; Fairchild, Geoffrey; Deshpande, Alina; Del Valle, Sara Y

2017-01-01

Effective disease monitoring provides a foundation for effective public health systems. This has historically been accomplished with patient contact and bureaucratic aggregation, which tends to be slow and expensive. Recent internet-based approaches promise to be real-time and cheap, with few parameters. However, the question of when and how these approaches work remains open. We addressed this question using Wikipedia access logs and category links. Our experiments, replicable and extensible using our open source code and data, test the effect of semantic article filtering, amount of training data, forecast horizon, and model staleness by comparing across 6 diseases and 4 countries using thousands of individual models. We found that our minimal-configuration, language-agnostic article selection process based on semantic relatedness is effective for improving predictions, and that our approach is relatively insensitive to the amount and age of training data. We also found, in contrast to prior work, very little forecasting value, and we argue that this is consistent with theoretical considerations about the nature of forecasting. These mixed results lead us to propose that the currently observational field of internet-based disease surveillance must pivot to include theoretical models of information flow as well as controlled experiments based on simulations of disease.

Flight-Test Evaluation of Flutter-Prediction Methods

NASA Technical Reports Server (NTRS)

Lind, RIck; Brenner, Marty

2003-01-01

The flight-test community routinely spends considerable time and money to determine a range of flight conditions, called a flight envelope, within which an aircraft is safe to fly. The cost of determining a flight envelope could be greatly reduced if there were a method of safely and accurately predicting the speed associated with the onset of an instability called flutter. Several methods have been developed with the goal of predicting flutter speeds to improve the efficiency of flight testing. These methods include (1) data-based methods, in which one relies entirely on information obtained from the flight tests and (2) model-based approaches, in which one relies on a combination of flight data and theoretical models. The data-driven methods include one based on extrapolation of damping trends, one that involves an envelope function, one that involves the Zimmerman-Weissenburger flutter margin, and one that involves a discrete-time auto-regressive model. An example of a model-based approach is that of the flutterometer. These methods have all been shown to be theoretically valid and have been demonstrated on simple test cases; however, until now, they have not been thoroughly evaluated in flight tests. An experimental apparatus called the Aerostructures Test Wing (ATW) was developed to test these prediction methods.

Toward a Relationship Perspective on Aggression among Schoolchildren: Integrating Social Cognitive and Interdependence Theories

PubMed Central

Card, Noel A.

2011-01-01

The traditional psychological approach of studying aggression among schoolchildren in terms of individual differences in aggression and in victimization has been valuable in identifying prevalence rates, risk, and consequences of involvement in aggression. However, it is argued that a focus on aggressor-victim relationships is warranted based on both conceptual and empirical grounds. Such a shift in focus requires modification and integration of existing theories of aggression, and this paper integrates social cognitive theory and interdependence theory to suggest a new, interdependent social cognitive theory of aggression. Specifically, this paper identifies points of overlap and different foci between these theories, and it illustrates their integration through a proposed model of the emergence of aggressor-victim interactions and relationships. The paper concludes that expanding consideration to include aggressor-victim relationships among schoolchildren offers considerable theoretical, empirical, and intervention opportunities. PMID:26985397

Water content of latent fingerprints - Dispelling the myth.

PubMed

Kent, Terry

2016-09-01

Changing procedures in the handling of rare and precious documents in museums and elsewhere, based on assumptions about constituents of latent fingerprints, have led the author to an examination of available data. These changes appear to have been triggered by one paper using general biological data regarding eccrine sweat production to infer that deposited fingerprints are mostly water. Searching the fingerprint literature has revealed a number of reference works similarly quoting figures for average water content of deposited fingerprints of 98% or more. Whilst accurate estimation is difficult there is no evidence that the residue on fingers could be anything like 98% water, even if there were no contamination from sebaceous glands. Consideration of published analytical data of real fingerprints, and several theoretical considerations regarding evaporation and replenishment rates, indicates a probable initial average water content of a fingerprint, soon after deposition, of 20% or less. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

"Applying anatomy to something I care about": Authentic inquiry learning and student experiences of an inquiry project.

PubMed

Anstey, Lauren M

2017-11-01

Despite advances to move anatomy education away from its didactic history, there is a continued need for students to contextualize their studies to make learning more meaningful. This article investigates authentic learning in the context of an inquiry-based approach to learning human gross anatomy. Utilizing a case-study design with three groups of students (n = 18) and their facilitators (n = 3), methods of classroom observations, interviews, and artifact collection were utilized to investigate students' experiences of learning through an inquiry project. Qualitative data analysis through open and selective coding produced common meaningful themes of group and student experiences. Overall results demonstrate how the project served as a unique learning experience where learners engaged in the opportunity to make sense of anatomy in context of their interests and wider interdisciplinary considerations through collaborative, group-based investigation. Results were further considered in context of theoretical frameworks of inquiry-based and authentic learning. Results from this study demonstrate how students can engage anatomical understandings to inquire and apply disciplinary considerations to their personal lives and the world around them. Anat Sci Educ 10: 538-548. © 2017 American Association of Anatomists. © 2017 American Association of Anatomists.

Ecosystem-based fisheries management: Perception on definitions, implementations, and aspirations.

PubMed

Trochta, John T; Pons, Maite; Rudd, Merrill B; Krigbaum, Melissa; Tanz, Alexander; Hilborn, Ray

2018-01-01

Ecosystem-based fisheries management (EBFM) was developed to move beyond single species management by incorporating ecosystem considerations for the sustainable utilization of marine resources. Due to the wide range of fishery characteristics, including different goals of fisheries management across regions and species, theoretical best practices for EBFM vary greatly. Here we highlight the lack of consensus in the interpretation of EBFM amongst professionals in marine science and its implementation. Fisheries policy-makers and managers, stock assessment scientists, conservationists, and ecologists had very different opinions on the degree to which certain management strategies would be considered EBFM. We then assess the variability of the implementation of EBFM, where we created a checklist of characteristics typifying EBFM and scored fisheries across different regions, species, ecosystems, and fishery size and capacity. Our assessments show fisheries are unlikely to meet all the criteria on the EBFM checklist. Consequentially, it is unnecessary for management to practice all the traits of EBFM, as some may be disparate from the ecosystem attributes or fishery goals. Instead, incorporating some ecosystem-based considerations to fisheries management that are context-specific is a more realistic and useful way for EBFM to occur in practice.

Ecosystem-based fisheries management: Perception on definitions, implementations, and aspirations

PubMed Central

Hilborn, Ray

2018-01-01

Ecosystem-based fisheries management (EBFM) was developed to move beyond single species management by incorporating ecosystem considerations for the sustainable utilization of marine resources. Due to the wide range of fishery characteristics, including different goals of fisheries management across regions and species, theoretical best practices for EBFM vary greatly. Here we highlight the lack of consensus in the interpretation of EBFM amongst professionals in marine science and its implementation. Fisheries policy-makers and managers, stock assessment scientists, conservationists, and ecologists had very different opinions on the degree to which certain management strategies would be considered EBFM. We then assess the variability of the implementation of EBFM, where we created a checklist of characteristics typifying EBFM and scored fisheries across different regions, species, ecosystems, and fishery size and capacity. Our assessments show fisheries are unlikely to meet all the criteria on the EBFM checklist. Consequentially, it is unnecessary for management to practice all the traits of EBFM, as some may be disparate from the ecosystem attributes or fishery goals. Instead, incorporating some ecosystem-based considerations to fisheries management that are context-specific is a more realistic and useful way for EBFM to occur in practice. PMID:29381700

Nonlinear Poisson equation for heterogeneous media.

PubMed

Hu, Langhua; Wei, Guo-Wei

2012-08-22

The Poisson equation is a widely accepted model for electrostatic analysis. However, the Poisson equation is derived based on electric polarizations in a linear, isotropic, and homogeneous dielectric medium. This article introduces a nonlinear Poisson equation to take into consideration of hyperpolarization effects due to intensive charges and possible nonlinear, anisotropic, and heterogeneous media. Variational principle is utilized to derive the nonlinear Poisson model from an electrostatic energy functional. To apply the proposed nonlinear Poisson equation for the solvation analysis, we also construct a nonpolar solvation energy functional based on the nonlinear Poisson equation by using the geometric measure theory. At a fixed temperature, the proposed nonlinear Poisson theory is extensively validated by the electrostatic analysis of the Kirkwood model and a set of 20 proteins, and the solvation analysis of a set of 17 small molecules whose experimental measurements are also available for a comparison. Moreover, the nonlinear Poisson equation is further applied to the solvation analysis of 21 compounds at different temperatures. Numerical results are compared to theoretical prediction, experimental measurements, and those obtained from other theoretical methods in the literature. A good agreement between our results and experimental data as well as theoretical results suggests that the proposed nonlinear Poisson model is a potentially useful model for electrostatic analysis involving hyperpolarization effects. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Computer integrated documentation

NASA Technical Reports Server (NTRS)

Boy, Guy

1991-01-01

The main technical issues of the Computer Integrated Documentation (CID) project are presented. The problem of automation of documents management and maintenance is analyzed both from an artificial intelligence viewpoint and from a human factors viewpoint. Possible technologies for CID are reviewed: conventional approaches to indexing and information retrieval; hypertext; and knowledge based systems. A particular effort was made to provide an appropriate representation for contextual knowledge. This representation is used to generate context on hypertext links. Thus, indexing in CID is context sensitive. The implementation of the current version of CID is described. It includes a hypertext data base, a knowledge based management and maintenance system, and a user interface. A series is also presented of theoretical considerations as navigation in hyperspace, acquisition of indexing knowledge, generation and maintenance of a large documentation, and relation to other work.

Knowledge representation and management enabling intelligent interoperability - principles and standards.

PubMed

Blobel, Bernd

2013-01-01

Based on the paradigm changes for health, health services and underlying technologies as well as the need for at best comprehensive and increasingly automated interoperability, the paper addresses the challenge of knowledge representation and management for medical decision support. After introducing related definitions, a system-theoretical, architecture-centric approach to decision support systems (DSSs) and appropriate ways for representing them using systems of ontologies is given. Finally, existing and emerging knowledge representation and management standards are presented. The paper focuses on the knowledge representation and management part of DSSs, excluding the reasoning part from consideration.

PV cells electrical parameters measurement

NASA Astrophysics Data System (ADS)

Cibira, Gabriel

2017-12-01

When measuring optical parameters of a photovoltaic silicon cell, precise results bring good electrical parameters estimation, applying well-known physical-mathematical models. Nevertheless, considerable re-combination phenomena might occur in both surface and intrinsic thin layers within novel materials. Moreover, rear contact surface parameters may influence close-area re-combination phenomena, too. Therefore, the only precise electrical measurement approach is to prove assumed cell electrical parameters. Based on theoretical approach with respect to experiments, this paper analyses problems within measurement procedures and equipment used for electrical parameters acquisition within a photovoltaic silicon cell, as a case study. Statistical appraisal quality is contributed.

Polarization-based compensation of astigmatism.

PubMed

Chowdhury, Dola Roy; Bhattacharya, Kallol; Chakraborty, Ajay K; Ghosh, Raja

2004-02-01

One approach to aberration compensation of an imaging system is to introduce a suitable phase mask at the aperture plane of an imaging system. We utilize this principle for the compensation of astigmatism. A suitable polarization mask used on the aperture plane together with a polarizer-retarder combination at the input of the imaging system provides the compensating polarization-induced phase steps at different quadrants of the apertures masked by different polarizers. The aberrant phase can be considerably compensated by the proper choice of a polarization mask and suitable selection of the polarization parameters involved. The results presented here bear out our theoretical expectation.

Screening of liquids for thermocapillary bubble movement

NASA Technical Reports Server (NTRS)

Wilcox, W. R.; Subramanian, R. S.; Papazian, J. M.; Smith, H. D.; Mattox, D. M.

1979-01-01

Ground-based methods for pretesting qualitatively the thermocapillary movement of gas bubbles in a liquid to be used in space processing are discussed. Theoretical considerations are shown to require the use of a thin, enclosed, horizontal liquid film in order that the bubbles move faster than the bulk convection of the liquid, with insulating boundaries to prevent the onset of instabilities. Experimental realizations of horizontal cells in which to test the thermocapillary movement of bubbles in sheets of molten glass heated from below and organic melts in tubes heated from both ends are briefly described and the results of experiments are indicated.

Scattering properties of natural snow and frost - Comparison with icy satellite photometry

NASA Technical Reports Server (NTRS)

Verbiscer, Anne J.; Veverka, Joseph

1990-01-01

The Hapke (1986) equation is presently fit to ascertain the single-scattering albedo of the icy satellites of Uranus and Neptune and the one-term Henyey-Greenstein particle-phase function g for each of the Middleton and Mungall (1952) goniophotometric data samples. There emerge both very high single-scattering albedos and strongly forward-scattering particle phase functions; while these are in keeping with Mie theory-based theoretical considerations, they contrast with the observed backscattering behavior of icy satellites. It is suggested the icy satellite frost grains are aggregated into particles of complex texture, which produce the unusual backscattering behavior.

Spin dependent transport properties of Mn-Ga/MgO/Mn-Ga magnetic tunnel junctions with metal(Mg, Co, Cr) insertion layer

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

Liang, S. H.; Tao, L. L.; Liu, D. P., E-mail: dpliu@iphy.ac.cn

We report a first principles theoretical investigation of spin polarized quantum transport in Mn{sub 2}Ga/MgO/Mn{sub 2}Ga and Mn{sub 3}Ga/MgO/Mn{sub 3}Ga magnetic tunneling junctions (MTJs) with the consideration of metal(Mg, Co, Cr) insertion layer effect. By changing the concentration of Mn, our calculation shows a considerable disparity in transport properties: A tunneling magnetoresistance (TMR) ratio of 852% was obtained for Mn{sub 2}Ga-based MTJs, however, only a 5% TMR ratio for Mn{sub 3}Ga-based MTJs. In addition, the influence of insertion layer has been considered in our calculation. We found the Co insertion layer can increase the TMR of Mn{sub 2}Ga-based MTJ tomore » 904%; however, the Cr insertion layer can decrease the TMR by 668%; A negative TMR ratio can be obtained with Mg insertion layer. Our work gives a comprehensive understanding of the influence of different insertion layer in Mn-Ga based MTJs. It is proved that, due to the transmission can be modulated by the interfacial electronic structure of insertion, the magnetoresistance ratio of Mn{sub 2}Ga/MgO/Mn{sub 2}Ga MTJ can be improved by inserting Co layer.« less

A new theoretical basis for numerical simulations of nonlinear acoustic fields

NASA Astrophysics Data System (ADS)

Wójcik, Janusz

2000-07-01

Nonlinear acoustic equations can be considerably simplified. The presented model retains the accuracy of a more complex description of nonlinearity and a uniform description of near and far fields (in contrast to the KZK equation). A method has been presented for obtaining solutions of Kuznetsov's equation from the solutions of the model under consideration. Results of numerical calculations, including comparative ones, are presented.

Computational modeling of GTA (gas tungsten arc) welding with emphasis on surface tension effects

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

Zacharia, T.; David, S.A.

1990-01-01

A computational study of the convective heat transfer in the weld pool during gas tungsten arch (GTA) welding of Type 304 stainless steel is presented. The solution of the transport equations is based on a control volume approach which utilized directly, the integral form of the governing equations. The computational model considers buoyancy and electromagnetic and surface tension forces in the solution of convective heat transfer in the weld pool. In addition, the model treats the weld pool surface as a deformable free surface. The computational model includes weld metal vaporization and temperature dependent thermophysical properties. The results indicate thatmore » consideration of weld pool vaporization effects and temperature dependent thermophysical properties significantly influence the weld model predictions. Theoretical predictions of the weld pool surface temperature distributions and the cross-sectional weld pool size and shape wee compared with corresponding experimental measurements. Comparison of the theoretically predicted and the experimentally obtained surface temperature profiles indicated agreement with {plus minus} 8%. The predicted weld cross-section profiles were found to agree very well with actual weld cross-sections for the best theoretical models. 26 refs., 8 figs.« less

AIRBORNE INVESTIGATIONS OF CLEAR AIR TURBULENCE WITH OPTICAL RADAR.

DTIC Science & Technology

relevant meteorlogical data. The design of this equipment and the development of the flight programs was predicated on theoretical considerations of optical scattering from particulate matter. (Author)

Anxiety: towards a decision-theoretic perspective.

PubMed

Shechter, M; Zeidner, M

1990-05-01

This paper sets out to illustrate how anxiety may be incorporated into a formal decision theoretic utility model of choice, and to suggest several measurement procedures towards that end. The major propositions derived and posited in this paper lend considerable support to intuitive notions with respect to the effects of anxiety on human behaviour in risky decision situations. Namely, that the willingness of an individual to pay to reduce health risks (an economic indicator of individual welfare associated with reduced morbidity or increased longevity) tends to be positive and higher when anxiety is present than when it is not. The formal results of the analysis show that when psychological considerations are incorporated into a state-dependent utility model, the normative results customarily obtained concerning value-of-life need to be qualified.

Theoretical Dipole Moment for the X211 State of NO

NASA Technical Reports Server (NTRS)

Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Partridge, Harry; Arnold, James O. (Technical Monitor)

1994-01-01

The dipole moment function for the X(sup 2)II state of NO is studied as a function of the completeness in both the one- and n-particle spaces. Einstein coefficients are presented that are significantly more accurate than previous tabulations for the higher vibrational levels. The theoretical values give considerable insight into the limitations of recently published ratios of Einstein coefficients measured by spectrally resolved infrared chemiluminescence.

Laser diagnostics for combustion temperature and species

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

Eckbreth, A.C.

1987-01-01

Laser approaches to combustion diagnostics are of considerable interest due to their remote, nonintrusive and in-situ character, unlimited temperature capability and potential for simultaneous temporal and spatial resolution, This book aims to make these powerful and important new tools in combustion research understandable. The focus of this text is on spectroscopically-based, spatially-precise laser techniques for temperature and chemical composition measurements in reacting and nonreacting flows. After introductory chapters providing a fundamental theoretical and experimental background, attention is directed to diagnostics based upon spontaneous Raman and Rayleigh scattering, coherent anti-Stokes Raman spectroscopy (CARS) and laser-induced fluorescence (LIFS). The book concludes withmore » a treatment of techniques which permit spatially-resolved measurements over an entire two-dimensional field simultaneously.« less

A fluid-mechanic-based model for the sedimentation of flocculated suspensions

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

Chhabra, R.P.; Prasad, D.

1991-02-01

Due to the wide occurrence of the suspensions of fine particles in mineral and chemical processing industries, considerable interest has been shown in modeling the hydrodynamic behavior of such systems. A fluid-mechanic-based analysis is presented for the settling behavior of flocculated4d suspensions. Flocs have been modeled as composite spheres consisting of a solid core embedded in a shell of homogeneous and isotropic porous medium. Theoretical estimates of the rates of sedimentation for flocculated suspensions are obtained by solving the equations of continuity and of motion. The interparticle interactions are incorporated into the analysis by employing the Happel free surface cellmore » model. The results reported embrace wide ranges of conditions of floc size and concentration.« less

Statistical design of quantitative mass spectrometry-based proteomic experiments.

PubMed

Oberg, Ann L; Vitek, Olga

2009-05-01

We review the fundamental principles of statistical experimental design, and their application to quantitative mass spectrometry-based proteomics. We focus on class comparison using Analysis of Variance (ANOVA), and discuss how randomization, replication and blocking help avoid systematic biases due to the experimental procedure, and help optimize our ability to detect true quantitative changes between groups. We also discuss the issues of pooling multiple biological specimens for a single mass analysis, and calculation of the number of replicates in a future study. When applicable, we emphasize the parallels between designing quantitative proteomic experiments and experiments with gene expression microarrays, and give examples from that area of research. We illustrate the discussion using theoretical considerations, and using real-data examples of profiling of disease.

Recent advances in plasma devices based on plasma lens configuration for manipulating high-current heavy ion beams.

PubMed

Dobrovolskiy, A; Dunets, S; Evsyukov, A; Goncharov, A; Gushenets, V; Litovko, I; Oks, E

2010-02-01

We describe new results of development of novel generation cylindrical plasma devices based on the electrostatic plasma lens configuration and concept of electrons magnetic insulation. The crossed electric and magnetic fields plasma lens configuration provides us with the attractive and suitable method for establishing a stable plasma discharge at low pressure. Using plasma lens configuration in this way some cost-effective plasma devices were developed for ion treatment and deposition of exotic coatings and the effective lens was first proposed for manipulating high-current beams of negatively charged particles. Here we describe operation and features of these plasma devices, and results of theoretical consideration of mechanisms determining their optimal operation conditions.

Computer vision, camouflage breaking and countershading

PubMed Central

Tankus, Ariel; Yeshurun, Yehezkel

2008-01-01

Camouflage is frequently used in the animal kingdom in order to conceal oneself from visual detection or surveillance. Many camouflage techniques are based on masking the familiar contours and texture of the subject by superposition of multiple edges on top of it. This work presents an operator, Darg, for the detection of three-dimensional smooth convex (or, equivalently, concave) objects. It can be used to detect curved objects on a relatively flat background, regardless of image edges, contours and texture. We show that a typical camouflage found in some animal species seems to be a ‘countermeasure’ taken against detection that might be based on our method. Detection by Darg is shown to be very robust, from both theoretical considerations and practical examples of real-life images. PMID:18990669

Improving the output voltage waveform of an intense electron-beam accelerator based on helical type Blumlein pulse forming line

NASA Astrophysics Data System (ADS)

Cheng, Xin-Bing; Liu, Jin-Liang; Zhang, Hong-Bo; Feng, Jia-Huai; Qian, Bao-Liang

2010-07-01

The Blumlein pulse forming line (BPFL) consisting of an inner coaxial pulse forming line (PFL) and an outer coaxial PFL is widely used in the field of pulsed power, especially for intense electron-beam accelerators (IEBA). The output voltage waveform determines the quality and characteristics of the output beam current of the IEBA. Comparing with the conventional BPFL, an IEBA based on a helical type BPFL can increase the duration of the output voltage in the same geometrical volume. However, for the helical type BPFL, the voltage waveform on a matched load may be distorted which influences the electron-beam quality. In this paper, an IEBA based on helical type BPFL is studied theoretically. Based on telegrapher equations of the BPFL, a formula for the output voltage of IEBA is obtained when the transition section is taken into account, where the transition section is between the middle cylinder of BPFL and the load. From the theoretical analysis, it is found that the wave impedance and transit time of the transition section influence considerably the main pulse voltage waveform at the load, a step is formed in front of the main pulse, and a sharp spike is also formed at the end of the main pulse. In order to get a well-shaped square waveform at the load and to improve the electron-beam quality of such an accelerator, the wave impedance of the transition section should be equal to that of the inner PFL of helical type BPFL and the transit time of the transition section should be designed as short as possible. Experiments performed on an IEBA with the helical type BPFL show reasonable agreement with theoretical analysis.

A queer-theoretical approach to community health psychology.

PubMed

Easpaig, Bróna R Nic Giolla; Fryer, David M; Linn, Seònaid E; Humphrey, Rhianna H

2014-01-01

Queer-theoretical resources offer ways of productively rethinking how central concepts such as 'person-context', 'identity' and 'difference' may be understood for community health psychologists. This would require going beyond consideration of the problems with which queer theory is popularly associated to cautiously engage with the aspects of this work relevant to the promotion of collective practice and engaging with processes of marginalisation. In this article, we will draw upon and illustrate the queer-theoretical concepts of 'performativity' and 'cultural intelligibility' before moving towards a preliminary mapping of what a queer-informed approach to community health psychology might involve.

The Roy Adaptation Model: A Theoretical Framework for Nurses Providing Care to Individuals With Anorexia Nervosa.

PubMed

Jennings, Karen M

Using a nursing theoretical framework to understand, elucidate, and propose nursing research is fundamental to knowledge development. This article presents the Roy Adaptation Model as a theoretical framework to better understand individuals with anorexia nervosa during acute treatment, and the role of nursing assessments and interventions in the promotion of weight restoration. Nursing assessments and interventions situated within the Roy Adaptation Model take into consideration how weight restoration does not occur in isolation but rather reflects an adaptive process within external and internal environments, and has the potential for more holistic care.

Design Considerations in Development of a Mobile Health Intervention Program: The TEXT ME and TEXTMEDS Experience

PubMed Central

Thakkar, Jay; Barry, Tony; Thiagalingam, Aravinda; Redfern, Julie; McEwan, Alistair L; Rodgers, Anthony

2016-01-01

Background Mobile health (mHealth) has huge potential to deliver preventative health services. However, there is paucity of literature on theoretical constructs, technical, practical, and regulatory considerations that enable delivery of such services. Objectives The objective of this study was to outline the key considerations in the development of a text message-based mHealth program; thus providing broad recommendations and guidance to future researchers designing similar programs. Methods We describe the key considerations in designing the intervention with respect to functionality, technical infrastructure, data management, software components, regulatory requirements, and operationalization. We also illustrate some of the potential issues and decision points utilizing our experience of developing text message (short message service, SMS) management systems to support 2 large randomized controlled trials: TEXT messages to improve MEDication adherence & Secondary prevention (TEXTMEDS) and Tobacco, EXercise and dieT MEssages (TEXT ME). Results The steps identified in the development process were: (1) background research and development of the text message bank based on scientific evidence and disease-specific guidelines, (2) pilot testing with target audience and incorporating feedback, (3) software-hardware customization to enable delivery of complex personalized programs using prespecified algorithms, and (4) legal and regulatory considerations. Additional considerations in developing text message management systems include: balancing the use of customized versus preexisting software systems, the level of automation versus need for human inputs, monitoring, ensuring data security, interface flexibility, and the ability for upscaling. Conclusions A merging of expertise in clinical and behavioral sciences, health and research data management systems, software engineering, and mobile phone regulatory requirements is essential to develop a platform to deliver and manage support programs to hundreds of participants simultaneously as in TEXT ME and TEXTMEDS trials. This research provides broad principles that may assist other researchers in developing mHealth programs. PMID:27847350

Design Considerations in Development of a Mobile Health Intervention Program: The TEXT ME and TEXTMEDS Experience.

PubMed

Thakkar, Jay; Barry, Tony; Thiagalingam, Aravinda; Redfern, Julie; McEwan, Alistair L; Rodgers, Anthony; Chow, Clara K

2016-11-15

Mobile health (mHealth) has huge potential to deliver preventative health services. However, there is paucity of literature on theoretical constructs, technical, practical, and regulatory considerations that enable delivery of such services. The objective of this study was to outline the key considerations in the development of a text message-based mHealth program; thus providing broad recommendations and guidance to future researchers designing similar programs. We describe the key considerations in designing the intervention with respect to functionality, technical infrastructure, data management, software components, regulatory requirements, and operationalization. We also illustrate some of the potential issues and decision points utilizing our experience of developing text message (short message service, SMS) management systems to support 2 large randomized controlled trials: TEXT messages to improve MEDication adherence & Secondary prevention (TEXTMEDS) and Tobacco, EXercise and dieT MEssages (TEXT ME). The steps identified in the development process were: (1) background research and development of the text message bank based on scientific evidence and disease-specific guidelines, (2) pilot testing with target audience and incorporating feedback, (3) software-hardware customization to enable delivery of complex personalized programs using prespecified algorithms, and (4) legal and regulatory considerations. Additional considerations in developing text message management systems include: balancing the use of customized versus preexisting software systems, the level of automation versus need for human inputs, monitoring, ensuring data security, interface flexibility, and the ability for upscaling. A merging of expertise in clinical and behavioral sciences, health and research data management systems, software engineering, and mobile phone regulatory requirements is essential to develop a platform to deliver and manage support programs to hundreds of participants simultaneously as in TEXT ME and TEXTMEDS trials. This research provides broad principles that may assist other researchers in developing mHealth programs. ©Jay Thakkar, Tony Barry, Aravinda Thiagalingam, Julie Redfern, Alistair L McEwan, Anthony Rodgers, Clara K Chow. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 15.11.2016.

Some considerations on the definition of risk based on concepts of systems theory and probability.

PubMed

Andretta, Massimo

2014-07-01

The concept of risk has been applied in many modern science and technology fields. Despite its successes in many applicative fields, there is still not a well-established vision and universally accepted definition of the principles and fundamental concepts of the risk assessment discipline. As emphasized recently, the risk fields suffer from a lack of clarity on their scientific bases that can define, in a unique theoretical framework, the general concepts in the different areas of application. The aim of this article is to make suggestions for another perspective of risk definition that could be applied and, in a certain sense, generalize some of the previously known definitions (at least in the fields of technical and scientific applications). By drawing on my experience of risk assessment in different applicative situations (particularly in the risk estimation for major industrial accidents, and in the health and ecological risk assessment for contaminated sites), I would like to revise some general and foundational concepts of risk analysis in as consistent a manner as possible from the axiomatic/deductive point of view. My proposal is based on the fundamental concepts of the systems theory and of the probability. In this way, I try to frame, in a single, broad, and general theoretical context some fundamental concepts and principles applicable in many different fields of risk assessment. I hope that this article will contribute to the revitalization and stimulation of useful discussions and new insights into the key issues and theoretical foundations of risk assessment disciplines. © 2013 Society for Risk Analysis.

The Bobath (NDT) concept in adult neurological rehabilitation: what is the state of the knowledge? A scoping review. Part II: intervention studies perspectives.

PubMed

Vaughan-Graham, Julie; Cott, Cheryl; Wright, F Virginia

2015-01-01

The study's purpose was to describe the range of knowledge pertaining to the Bobath (NDT) concept in adult neurological rehabilitation, synthesizes the findings, identify knowledge gaps and develop empirically based recommendations for future research. A scoping review of research and non-research articles published from 2007 to 2012. Two independent reviewers selected studies based on a systematic procedure. Inclusion criteria for studies were electronically accessible English language literature with Bobath and/or Neurodevelopmental Therapy as the subject heading in the title/keyword/abstract/intervention comparison with respect to adult neurological conditions. Data were abstracted and summarized with respect to study design, theoretical framework, clinical application including population representation, study fidelity, intervention comparison, duration of care, measurement and findings. Of the 33 publications identified 17 were intervention studies (11 RCT's/1 prospective parallel group design/5 N-of-1). One other paper was a systematic review. The intervention studies, primarily RCT designs, have serious methodological concerns particularly related to study/treatment fidelity and measurement resulting in no clear clinical direction. Aspects such as theoretical framework, therapist skill, quality of movement measurement and individualized interventions require careful consideration in the design of Bobath studies. Implications for Rehabilitation Future intervention studies should be based on the current Bobath theoretical framework and key aspects of clinical practice. Study and treatment fidelity issues need to be carefully considered when interpreting the results of existing RCT's evaluating the Bobath concept. N-of-1 randomized, observational, factorial and mixed method study designs should be considered as alternative study options.

Superposition rheology.

PubMed

Dhont, J K; Wagner, N J

2001-02-01

The interpretation of superposition rheology data is still a matter of debate due to lack of understanding of viscoelastic superposition response on a microscopic level. So far, only phenomenological approaches have been described, which do not capture the shear induced microstructural deformation, which is responsible for the viscoelastic behavior to the superimposed flow. Experimentally there are indications that there is a fundamental difference between the viscoelastic response to an orthogonally and a parallel superimposed shear flow. We present theoretical predictions, based on microscopic considerations, for both orthogonal and parallel viscoelastic response functions for a colloidal system of attractive particles near their gas-liquid critical point. These predictions extend to values of the stationary shear rate where the system is nonlinearly perturbed, and are based on considerations on the colloidal particle level. The difference in response to orthogonal and parallel superimposed shear flow can be understood entirely in terms of microstructural distortion, where the anisotropy of the microstructure under shear flow conditions is essential. In accordance with experimental observations we find pronounced negative values for response functions in case of parallel superposition for an intermediate range of frequencies, provided that microstructure is nonlinearly perturbed by the stationary shear component. For the critical colloidal systems considered here, the Kramers-Kronig relations for the superimposed response functions are found to be valid. It is argued, however, that the Kramers-Kronig relations may be violated for systems where the stationary shear flow induces a considerable amount of new microstructure.

Ludwig von Bertalanffy's Organismic View on the Theory of Evolution

PubMed Central

Drack, Manfred

2015-01-01

Ludwig von Bertalanffy was a key figure in the advancement of theoretical biology. His early considerations already led him to recognize the necessity of considering the organism as a system, as an organization of parts and processes. He termed the resulting research program organismic biology, which he extended to all basic questions of biology and almost all areas of biology, hence also to the theory of evolution. This article begins by outlining the rather unknown (because often written in German) research of Bertalanffy in the field of theoretical biology. The basics of the organismic approach are then described. This is followed by Bertalanffy's considerations on the theory of evolution, in which he used methods from theoretical biology and then introduced his own, organismic, view on evolution, leading to the demand for finding laws of evolution. Finally, his view on the concept of homology is presented. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 77–90, 2015. © 2015 The Authors. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution published by Wiley Periodicals, Inc. PMID:25727202

[Biophilosophical and epistemological problems in the study of living beings: reflections on the views of Humberto Maturana].

PubMed

Serani-Merlo, A

2001-01-01

Theories on the nature of living beings have been present in our culture since the beginnings of science and philosophy in ancient Greece. The two major theoretical approaches to living beings, philosophical mechanism and Aristotelian realism, appear today with renewed force in almost every confrontation concerning the theoretical considerations of life. In recent times a strong and prolific school of thought has risen, headed by the Chilean neurobiologist Humberto Maturana. This author and his school have developed a complex and articulated theoretical system beginning with a theory of living beings and a 'biology of cognition,' and extending to ethical, political, and even metaphysical considerations. This work is one of the first efforts to perform a scholarly analysis of Maturana's doctrines on living beings, starting with the analysis of "On machines and living beings". The book's introduction is placed under scrutiny in this paper. A strongly mechanist philosophical manifesto is dogmatically stated at the beginning of a supposedly purely scientific approach. The challenges for a rational foundation of philosophical mechanism are critically highlighted and briefly discussed.

Avoiding piecemeal research on participation in cervical cancer screening: the advantages of a social identity framework

PubMed Central

Tribe, Candice; Webb, Janine

2012-01-01

Abstract Background  Cervical cancer screening research has predominantly focused on one type of participation, namely compliance with medical recommendations, and has largely ignored other types of participation. While there is some research that has taken a different approach, findings in this research area are not well integrated under a theoretical framework. Objective  The aim of this study is to show how consideration of a broader definition of participation and better integration of the theoretical conceptualization of participation in cervical cancer screening are both possible and desirable to enable a better understanding of women’s experiences of cervical cancer screening specifically and to improve women’s health generally. Main Conclusion  It is suggested that alternative types of participation in cervical cancer screening warrant further investigation and that a social identity theoretical approach offers one way of integrating such conceptualizations of participation. The paper also argues for more explicit consideration of the role of social processes and of the variables, such as power, social identity and relational justice, which are involved in participation in cervical cancer screening. PMID:22646802

Theoretical studies on the mechanical behavior of granular materials under very low intergranular stresses

NASA Technical Reports Server (NTRS)

French, Kenneth W., Jr.

1986-01-01

The salient aspects of the theoretical modeling of a conventional triaxial test (CTC) of a cohesionless granular medium with stress and strain rate loading are described. Included are a controllable gravitational body force and provision for low confining pressure and/or very low intergranular stress. The modeling includes rational, analytic, and numerical phases, all in various stages of development. The numerical evolutions of theoretical models will be used in final design stages and in the analysis of the experimental data. In this the experimental design stage, it is of special interest to include in the candidate considerations every anomaly found in preliminary terrestrial experimentation. Most of the anomalies will be eliminated by design or enhanced for measurement as the project progresses. The main aspect of design being not the physical apparatus but the type and trajectories of loading elected. The major considerations that have been treated are: appearance and growth of local surface aberrations, stress-power coefficients, strain types, optical strain, radial bead migration, and measures of rotation for the proper stress flux.

The Relationship Between Father-Absence and Encopresis

ERIC Educational Resources Information Center

Schaengold, Marilyn

1977-01-01

A review of the literature on encopresis shows strong emphasis on father-absence as a dominant factor. Other characteristics of patients and their families are listed, and theoretical considerations discussed. (MS)

Integrated optical circuit engineering V; Proceedings of the Meeting, San Diego, CA, Aug. 17-20, 1987

NASA Astrophysics Data System (ADS)

Mentzer, Mark A.

Recent advances in the theoretical and practical design and applications of optoelectronic devices and optical circuits are examined in reviews and reports. Topics discussed include system and market considerations, guided-wave phenomena, waveguide devices, processing technology, lithium niobate devices, and coupling problems. Consideration is given to testing and measurement, integrated optics for fiber-optic systems, optical interconnect technology, and optical computing.

Coherent and incoherent ultrasound backscatter from cell aggregates.

PubMed

de Monchy, Romain; Destrempes, François; Saha, Ratan K; Cloutier, Guy; Franceschini, Emilie

2016-09-01

The effective medium theory (EMT) was recently developed to model the ultrasound backscatter from aggregating red blood cells [Franceschini, Metzger, and Cloutier, IEEE Trans. Ultrason. Ferroelectr. Freq. Control 58, 2668-2679 (2011)]. The EMT assumes that aggregates can be treated as homogeneous effective scatterers, which have effective properties determined by the aggregate compactness and the acoustical characteristics of the cells and the surrounding medium. In this study, the EMT is further developed to decompose the differential backscattering cross section of a single cell aggregate into coherent and incoherent components. The coherent component corresponds to the squared norm of the average scattering amplitude from the effective scatterer, and the incoherent component considers the variance of the scattering amplitude (i.e., the mean squared norm of the fluctuation of the scattering amplitude around its mean) within the effective scatterer. A theoretical expression for the incoherent component based on the structure factor is proposed and compared with another formulation based on the Gaussian direct correlation function. This theoretical improvement is assessed using computer simulations of ultrasound backscatter from aggregating cells. The consideration of the incoherent component based on the structure factor allows us to approximate the simulations satisfactorily for a product of the wavenumber times the aggregate radius kr ag around 2.

Preliminary design of turbopumps and related machinery

NASA Technical Reports Server (NTRS)

Wislicenus, George F.

1986-01-01

Pumps used in large liquid-fuel rocket engines are examined. The term preliminary design denotes the initial, creative phases of design, where the general shape and characteristics of the machine are determined. This compendium is intended to provide the design engineer responsible for these initial phases with a physical understanding and background knowledge of the numerous special fields involved in the design process. Primary attention is directed to the pumping part of the turbopump and hence is concerned with essentially incompressible fluids. However, compressible flow principles are developed. As much as possible, the simplicity and reliability of incompressible flow considerations are retained by treating the mechanics of compressible fluids as a departure from the theory of incompressible fluids. Five areas are discussed: a survey of the field of turbomachinery in dimensionless form; the theoretical principles of the hydrodynamic design of turbomachinery; the hydrodynamic and gas dynamic design of axial flow turbomachinery; the hydrodynamic and gas dynamic design of radial and mixed flow turbomachinery; and some mechanical design considerations of turbomachinery. Theoretical considerations are presented with a relatively elementary mathematical treatment.

[The human life cycle from a theoretical viewpoint].

PubMed

Beier, W

1976-02-15

In the view of theoretical considerations the human course of life is regarded as a generalized motion. It is made an attempt to define terms, such as chronological age, biological age and ageing. In the model of ageing irreversible alterations affecting the organism are described by a complex variable, called vitality, which represents the state of systems. The rate of vitality dV/dt and the biomorphosis of systems are equivalent terms.

Guidelines for clinical supervision in health service psychology.

PubMed

2015-01-01

This document outlines guidelines for supervision of students in health service psychology education and training programs. The goal was to capture optimal performance expectations for psychologists who supervise. It is based on the premises that supervisors (a) strive to achieve competence in the provision of supervision and (b) employ a competency-based, meta-theoretical approach to the supervision process. The Guidelines on Supervision were developed as a resource to inform education and training regarding the implementation of competency-based supervision. The Guidelines on Supervision build on the robust literatures on competency-based education and clinical supervision. They are organized around seven domains: supervisor competence; diversity; relationships; professionalism; assessment/evaluation/feedback; problems of professional competence, and ethical, legal, and regulatory considerations. The Guidelines on Supervision represent the collective effort of a task force convened by the American Psychological Association (APA) Board of Educational Affairs (BEA). PsycINFO Database Record (c) 2015 APA, all rights reserved.

Wavelength-adaptive dehazing using histogram merging-based classification for UAV images.

PubMed

Yoon, Inhye; Jeong, Seokhwa; Jeong, Jaeheon; Seo, Doochun; Paik, Joonki

2015-03-19

Since incoming light to an unmanned aerial vehicle (UAV) platform can be scattered by haze and dust in the atmosphere, the acquired image loses the original color and brightness of the subject. Enhancement of hazy images is an important task in improving the visibility of various UAV images. This paper presents a spatially-adaptive dehazing algorithm that merges color histograms with consideration of the wavelength-dependent atmospheric turbidity. Based on the wavelength-adaptive hazy image acquisition model, the proposed dehazing algorithm consists of three steps: (i) image segmentation based on geometric classes; (ii) generation of the context-adaptive transmission map; and (iii) intensity transformation for enhancing a hazy UAV image. The major contribution of the research is a novel hazy UAV image degradation model by considering the wavelength of light sources. In addition, the proposed transmission map provides a theoretical basis to differentiate visually important regions from others based on the turbidity and merged classification results.

Electronic Excitation in Molecular Collisions: Structural, Dynamic and Kinetic Considerations.

DTIC Science & Technology

1981-08-01

electronically excited species are examined. The problem is studied both in general terms (i.e., the development of the required theoretical framework ) and in application to specific systems. (Author)

Electronic Excitation in Molecular Collisions: Structural, Dynamic and Kinetic Considerations.

DTIC Science & Technology

1980-09-01

electronically excited species are examined. The problem is studied both in general terms (i.e., the development of the required theoretical framework ) and in application to specific systems. (Author)

Electronic Excitation in Molecular Collisions: Structural, Dynamic and Kinetic Considerations.

DTIC Science & Technology

1979-09-01

electronically excited species are examined. The problem is studied both in general terms (i.e., the development of the required theoretical framework ) and in application to specific systems. (Author)

Electronic Excitation in Molecular Collisions: Structural, Dynamic and Kinetic Considerations.

DTIC Science & Technology

electronically excited specied are examined. The problem is studied both in general terms (i.e., the development of the required theoretical framework ) and in application to specific systems. (Author)

Finite-time synchronization of fractional-order memristor-based neural networks with time delays.

PubMed

Velmurugan, G; Rakkiyappan, R; Cao, Jinde

2016-01-01

In this paper, we consider the problem of finite-time synchronization of a class of fractional-order memristor-based neural networks (FMNNs) with time delays and investigated it potentially. By using Laplace transform, the generalized Gronwall's inequality, Mittag-Leffler functions and linear feedback control technique, some new sufficient conditions are derived to ensure the finite-time synchronization of addressing FMNNs with fractional order α:1<α<2 and 0<α<1. The results from the theory of fractional-order differential equations with discontinuous right-hand sides are used to investigate the problem under consideration. The derived results are extended to some previous related works on memristor-based neural networks. Finally, three numerical examples are presented to show the effectiveness of our proposed theoretical results. Copyright © 2015 Elsevier Ltd. All rights reserved.

Acidity and alkalinity in mine drainage: Theoretical considerations

USGS Publications Warehouse

Kirby, Carl S.; Cravotta,, Charles A.

2004-01-01

Acidity, net acidity, and net alkalinity are widely used parameters for the characterization of mine drainage, but these terms are not well defined and are often misunderstood. Incorrect interpretation of acidity, alkalinity, and derivative terms can lead to inadequate treatment design or poor regulatory decisions. We briefly explain derivations of theoretical expressions of three types of alkalinities (caustic, phenolphthalein, and total) and acidities (mineral, CO2, and total). Theoretically defined total alkalinity is closely analogous to measured alkalinity and presents few practical interpretation problems. Theoretically defined “CO2- acidity” is closely related to most standard titration methods used for mine drainage with an endpoint pH of 8.3, but it presents numerous interpretation problems, and it is unfortunately named because CO2 is intentionally driven off during titration of mine-drainage samples. Using the proton condition/massaction approach and employing graphs for visualization, we explore the concept of principal components and how to assign acidity contributions to solution species, including aqueous complexes, commonly found in mine drainage. We define a comprehensive theoretical definition of acidity in mine drainage on the basis of aqueous speciation at the sample pH and the capacity of these species to undergo hydrolysis to pH 8.3. This definition indicates the computed acidity in milligrams per liter (mg L-1 ) as CaCO3 (based on pH and analytical concentrations of dissolved FeIII , FeII , Mn, and Al in mg L-1 ): Aciditycomputed = 50. (10(3-pH) + 3.CFeIII/55.8 + 2.CFeII/55.8 + 2.CMn/54.9 + 3.CAl/27.0) underestimates contributions from HSO4 - and H+ , but overestimates the acidity due to Fe3+. These errors tend to approximately cancel each other. We demonstrate that “net alkalinity” is a valid mathematical construction based on theoretical definitions of alkalinity and acidity. We demonstrate that, for most mine-drainage solutions, a useful net alkalinity value can be derived from: 1) alkalinity and acidity values based on aqueous speciation, 2) measured alkalinity - computed acidity, or 3) taking the negative of the value obtained in a standard method “hot peroxide” acidity titration, provided that labs report negative values. We recommend the third approach; i.e., Net alkalinity = - Hot Acidity.

Capturing microscopic features of bone remodeling into a macroscopic model based on biological rationales of bone adaptation.

PubMed

Kim, Young Kwan; Kameo, Yoshitaka; Tanaka, Sakae; Adachi, Taiji

2017-10-01

To understand Wolff's law, bone adaptation by remodeling at the cellular and tissue levels has been discussed extensively through experimental and simulation studies. For the clinical application of a bone remodeling simulation, it is significant to establish a macroscopic model that incorporates clarified microscopic mechanisms. In this study, we proposed novel macroscopic models based on the microscopic mechanism of osteocytic mechanosensing, in which the flow of fluid in the lacuno-canalicular porosity generated by fluid pressure gradients plays an important role, and theoretically evaluated the proposed models, taking biological rationales of bone adaptation into account. The proposed models were categorized into two groups according to whether the remodeling equilibrium state was defined globally or locally, i.e., the global or local uniformity models. Each remodeling stimulus in the proposed models was quantitatively evaluated through image-based finite element analyses of a swine cancellous bone, according to two introduced criteria associated with the trabecular volume and orientation at remodeling equilibrium based on biological rationales. The evaluation suggested that nonuniformity of the mean stress gradient in the local uniformity model, one of the proposed stimuli, has high validity. Furthermore, the adaptive potential of each stimulus was discussed based on spatial distribution of a remodeling stimulus on the trabecular surface. The theoretical consideration of a remodeling stimulus based on biological rationales of bone adaptation would contribute to the establishment of a clinically applicable and reliable simulation model of bone remodeling.

Global analysis of seasonal streamflow predictability using an ensemble prediction system and observations from 6192 small catchments worldwide

NASA Astrophysics Data System (ADS)

van Dijk, Albert I. J. M.; Peña-Arancibia, Jorge L.; Wood, Eric F.; Sheffield, Justin; Beck, Hylke E.

2013-05-01

Ideally, a seasonal streamflow forecasting system would ingest skilful climate forecasts and propagate these through calibrated hydrological models initialized with observed catchment conditions. At global scale, practical problems exist in each of these aspects. For the first time, we analyzed theoretical and actual skill in bimonthly streamflow forecasts from a global ensemble streamflow prediction (ESP) system. Forecasts were generated six times per year for 1979-2008 by an initialized hydrological model and an ensemble of 1° resolution daily climate estimates for the preceding 30 years. A post-ESP conditional sampling method was applied to 2.6% of forecasts, based on predictive relationships between precipitation and 1 of 21 climate indices prior to the forecast date. Theoretical skill was assessed against a reference run with historic forcing. Actual skill was assessed against streamflow records for 6192 small (<10,000 km2) catchments worldwide. The results show that initial catchment conditions provide the main source of skill. Post-ESP sampling enhanced skill in equatorial South America and Southeast Asia, particularly in terms of tercile probability skill, due to the persistence and influence of the El Niño Southern Oscillation. Actual skill was on average 54% of theoretical skill but considerably more for selected regions and times of year. The realized fraction of the theoretical skill probably depended primarily on the quality of precipitation estimates. Forecast skill could be predicted as the product of theoretical skill and historic model performance. Increases in seasonal forecast skill are likely to require improvement in the observation of precipitation and initial hydrological conditions.

Conducting a qualitative child interview: methodological considerations.

PubMed

Kortesluoma, Riitta-Liisa; Hentinen, Maija; Nikkonen, Merja

2003-06-01

Studies of children have a long history, but the literature related to young children consists for the most part of studies on rather than with children and taking little account of what is regarded as significant and meaningful by children themselves. Researchers have relied almost exclusively on adults when collecting data about children's thoughts, feelings and experiences. Interviewing children, however, gives an opportunity to gain information about their subjective experiences. The purpose of this article is to illustrate the theoretical premises of child interviewing, as well as to describe some practical methodological solutions used during interviews. Factors that influence data gathered from children and strategies for taking these factors into consideration during the interview are also described. This paper is based on literature and the experience of one of the authors in interviewing children aged from 4 to 11 years about their experiences of pain. A consideration of literature dealing with the principles of child interviewing shows that there is surprisingly little guidance available on conversational methods involving children. The empirical and conceptual foundation for child interviewing is not very clear. Novice researchers especially may need recommendations about how to conduct a qualitative child interview. The method must suit both the purpose and the context.

Information-theoretic limitations on approximate quantum cloning and broadcasting

NASA Astrophysics Data System (ADS)

Lemm, Marius; Wilde, Mark M.

2017-07-01

We prove quantitative limitations on any approximate simultaneous cloning or broadcasting of mixed states. The results are based on information-theoretic (entropic) considerations and generalize the well-known no-cloning and no-broadcasting theorems. We also observe and exploit the fact that the universal cloning machine on the symmetric subspace of n qudits and symmetrized partial trace channels are dual to each other. This duality manifests itself both in the algebraic sense of adjointness of quantum channels and in the operational sense that a universal cloning machine can be used as an approximate recovery channel for a symmetrized partial trace channel and vice versa. The duality extends to give control of the performance of generalized universal quantum cloning machines (UQCMs) on subspaces more general than the symmetric subspace. This gives a way to quantify the usefulness of a priori information in the context of cloning. For example, we can control the performance of an antisymmetric analog of the UQCM in recovering from the loss of n -k fermionic particles.

[Marxism as a theoretical and methodological framework in collective health: implications for systematic review and synthesis of evidence].

PubMed

Soares, Cassia Baldini; Campos, Celia Maria Sivalli; Yonekura, Tatiana

2013-12-01

In this study, we discuss the integration in systematic reviews of research developed from a Marxist perspective of knowledge production and their results as evidence in healthcare. The study objectives are to review the assumptions of dialectical and historical materialism (DHM) and discuss the implications of dialectics for a literature review and the synthesis of evidence. DHM is a powerful framework for knowledge generation and transformation of policies and practices in healthcare. It assumes that social contradictions underlie the health-disease process, the fundamental theoretical construction in the field of collective health. Currently, we observe a considerable influence of the critical paradigm, of Marxist origin, in the construction of knowledge in health. Studies based on this critical paradigm incorporate complex methods, which are inherent to the guidelines of dialect, to identify the object and arrive at results that constitute evidence in healthcare. Systematic reviews should address the methodological difficulties associated with entirely integrating these results to healthcare.

Equation of motion coupled cluster methods for electron attachment and ionization potential in polyacenes

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

Bhaskaran-Nair, Kiran; Kowalski, Karol; Jarrell, Mark

2015-11-05

Polyacenes have attracted considerable attention due to their use in organic based optoelectronic materials. Polyacenes are polycyclic aromatic hydrocarbons composed of fused benzene rings. Key to understanding and design of new functional materials is an understanding of their excited state properties starting with their electron affinity (EA) and ionization potential (IP). We have developed a highly accurate and com- putationally e*fficient EA/IP equation of motion coupled cluster singles and doubles (EA/IP-EOMCCSD) method that is capable of treating large systems and large basis set. In this study we employ the EA/IP-EOMCCSD method to calculate the electron affinity and ionization potential ofmore » naphthalene, anthracene, tetracene, pentacene, hex- acene and heptacene. We have compared our results with other previous theoretical studies and experimental data. Our EA/IP results are in very good agreement with experiment and when compared with the other theoretical investigations our results represent the most accurate calculations as compared to experiment.« less

Experimental and theoretical investigation of passive damping concepts for member forced and free vibration

NASA Technical Reports Server (NTRS)

Razzaq, Zia; Mykins, David W.

1987-01-01

Potential passive damping concepts for use in space structures are identified. The effectiveness of copper brush, wool swab, and silly putty in chamber dampers is investigated through natural vibration tests on a tubular aluminum member. The member ends have zero translation and possess partial rotational restraints. The silly putty in chamber dampers provide the maximum passive damping efficiency. Forced vibration tests are then conducted with one, two, and three damper chambers containing silly putty. Owing to the limitation of the vibrator used, the performance of these dampers could not be evaluated experimentally until the forcing function was disengaged. Nevertheless, their performance is evaluated through a forced dynamic finite element analysis conducted as a part of this investigation. The theoretical results based on experimentally obtained damping ratios indicate that the passive dampers are considerably more effective under member natural vibration than during forced vibration. Also, the maximum damping under forced vibration occurs at or near resonance.

Experimental and theoretical study of Co sorption in clay montmorillonites

NASA Astrophysics Data System (ADS)

Gil Rebaza, A. V.; Montes, M. L.; Taylor, M. A.; Errico, L. A.; Alonso, R. E.

2018-03-01

Montmorillonite (MMT) clays are 2:1 layered structures which in natural state may allocate different hydrated cations such as M-nH2O (M = Na, Ca, Fe, etc) in its interlayer space. Depending on the capability for ion sorption, these materials are interesting for environmental remediation. In this work we experimentally study the Co sorption in a natural Na-MMT using UV-visible spectrometry and XRD on semi-oriented samples, and then analyze the sorption ability of this clay by means of ab initio calculation performed on pristine MMT. The structural properties of Na-MMT and Co-adsorbed MMT, and the hyperfine parameters at different atomic sites were analyzed and compared with the experimental ones for the first, and for the case of the hyperfine parameters, presented for the first time for the last. The theoretical predictions based on total energy considerations confirm that Co incorporation replacing Na is energetically favorable. Also, the basal spacing d001 experimentally obtained is well reproduced.

Organizing the Confusion Surrounding Workaholism: New Structure, Measure, and Validation

PubMed Central

Shkoler, Or; Rabenu, Edna; Vasiliu, Cristinel; Sharoni, Gil; Tziner, Aharon

2017-01-01

Since “workaholism” was coined, a considerable body of research was conducted to shed light on its essence. After at least 40 years of studying this important phenomenon, a large variety of definitions, conceptualizations, and measures emerged. In order to try and bring more integration and consensus to this construct, the current research was conducted in two phases. We aimed to formulate a theoretical definitional framework for workaholism, capitalizing upon the Facet Theory Approach. Two basic facets were hypothesized: A. Modalities of workaholism, with three elements: cognitive, emotional, and instrumental; and B. Resources of workaholism with two elements: time and effort. Based on this definitional framework, a structured questionnaire was conceived. In the first phase, the new measure was validated with an Israeli sample comparing two statistical procedures; Factor Analysis (FA) and Smallest Space Analysis (SSA). In the second phase, we aimed to replicate the findings, and to contrast the newly-devised questionnaire with other extant workaholism measures, with a Romanian sample. Theoretical implications and future research suggestions are discussed. PMID:29097989

Pulse Front Tilt and Laser Plasma Acceleration

NASA Astrophysics Data System (ADS)

Mittelberger, Daniel; Thévenet, Maxence; Nakamura, Kei; Lehe, Remi; Gonsalves, Anthony; Benedetti, Carlo; Leemans, Wim

2017-10-01

Pulse front tilt (PFT) is potentially present in any CPA laser system, but its effects may be overlooked because spatiotemporal pulse characterization is considerably more involved than measuring only spatial or temporal profile. PFT is particularly important for laser plasma accelerators (LPA) because it influences electron beam injection and steering. In this work, experimental results from the BELLA Center will be presented that demonstrate the effect of optical grating misalignment and optical compression, resulting in PFT, on accelerator performance. Theoretical models of laser and electron beam steering will be introduced based on particle-in-cell simulations showing distortion of the plasma wake. Theoretical predictions will be compared with experiments and complimentary simulations, and tolerances on PFT and optical compressor alignment will be developed as a function of LPA performance requirements. This work was supported by the Office of High Energy Physics, Office of Science, US Department of Energy under Contract DE-AC02-05CH11231 and the National Science Foundation under Grant PHY-1415596.

Binocular disparities, motion parallax, and geometric perspective in Patrick Hughes's 'reverspectives': theoretical analysis and empirical findings.

PubMed

Rogers, Brian; Gyani, Alex

2010-01-01

Abstract. Patrick Hughes's 'reverspective' artworks provide a novel way of investigating the effectiveness of different sources of 3-D information for the human visual system. Our empirical findings show that the converging lines of simple linear perspective can be as effective as the rich array of 3-D cues present in natural scenes in determining what we see, even when these cues are in conflict with binocular disparities. Theoretical considerations reveal that, once the information provided by motion parallax transformations is correctly understood, there is no need to invoke higher-level processes or an interpretation based on familiarity or past experience in order to explain either the 'reversed' depth or the apparent, concomitant rotation of a reverspective artwork as the observer moves from side to side. What we see in reverspectives is the most likely real-world scenario (distal stimulus) that could have created the perspective and parallax transformations (proximal stimulus) that stimulate our visual systems.

Evaporation of LOX under supercritical and subcritical conditions

NASA Technical Reports Server (NTRS)

Yang, A. S.; Hsieh, W. H.; Kuo, K. K.; Brown, J. J.

1993-01-01

The evaporation of LOX under supercritical and subcritical conditions was studied experimentally and theoretically. In experiments, the evaporation rate and surface temperature were measured for LOX strand vaporizing in helium environments at pressures ranging from 5 to 68 atmospheres. Gas sampling and chromatography analysis were also employed to profile the gas composition above the LOX surface for the purpose of model validation. A comprehensive theoretical model was formulated and solved numerically to simulate the evaporation process of LOX at high pressures. The model was based on the conservation equations of mass, momentum, energy, and species concentrations for a multicomponent system, with consideration of gravitational body force, solubility of ambient gases in liquid, and variable thermophysical properties. Good agreement between predictions and measured oxygen mole fraction profiles was obtained. The effect of pressure on the distribution of the Lewis number, as well as the effect of variable diffusion coefficient, were further examined to elucidate the high-pressure transport behavior exhibited in the LOX vaporization process.

Steady-state equation of water vapor sorption for CaCl2-based chemical sorbents and its application

PubMed Central

Zhang, Haiquan; Yuan, Yanping; Sun, Qingrong; Cao, Xiaoling; Sun, Liangliang

2016-01-01

Green CaCl2-based chemical sorbent has been widely used in sorption refrigeration, air purification and air desiccation. Methods to improve the sorption rate have been extensively investigated, but the corresponding theoretical formulations have not been reported. In this paper, a sorption system of solid-liquid coexistence is established based on the hypothesis of steady-state sorption. The combination of theoretical analysis and experimental results indicates that the system can be described by steady-state sorption process. The steady-state sorption equation, μ = (η − γT) , was obtained in consideration of humidity, temperature and the surface area. Based on engineering applications and this equation, two methods including an increase of specific surface area and adjustment of the critical relative humidity (γ) for chemical sorbents, have been proposed to increase the sorption rate. The results indicate that the CaCl2/CNTs composite with a large specific surface area can be obtained by coating CaCl2 powder on the surface of carbon nanotubes (CNTs). The composite reached sorption equilibrium within only 4 h, and the sorption capacity was improved by 75% compared with pure CaCl2 powder. Furthermore, the addition of NaCl powder to saturated CaCl2 solution could significantly lower the solution’s γ. The sorption rate was improved by 30% under the same environment. PMID:27682811

Steady-state equation of water vapor sorption for CaCl2-based chemical sorbents and its application

NASA Astrophysics Data System (ADS)

Zhang, Haiquan; Yuan, Yanping; Sun, Qingrong; Cao, Xiaoling; Sun, Liangliang

2016-09-01

Green CaCl2-based chemical sorbent has been widely used in sorption refrigeration, air purification and air desiccation. Methods to improve the sorption rate have been extensively investigated, but the corresponding theoretical formulations have not been reported. In this paper, a sorption system of solid-liquid coexistence is established based on the hypothesis of steady-state sorption. The combination of theoretical analysis and experimental results indicates that the system can be described by steady-state sorption process. The steady-state sorption equation, μ = (η - γT) , was obtained in consideration of humidity, temperature and the surface area. Based on engineering applications and this equation, two methods including an increase of specific surface area and adjustment of the critical relative humidity (γ) for chemical sorbents, have been proposed to increase the sorption rate. The results indicate that the CaCl2/CNTs composite with a large specific surface area can be obtained by coating CaCl2 powder on the surface of carbon nanotubes (CNTs). The composite reached sorption equilibrium within only 4 h, and the sorption capacity was improved by 75% compared with pure CaCl2 powder. Furthermore, the addition of NaCl powder to saturated CaCl2 solution could significantly lower the solution’s γ. The sorption rate was improved by 30% under the same environment.

Critical dialogical approach: A methodological direction for occupation-based social transformative work.

PubMed

Farias, Lisette; Laliberte Rudman, Debbie; Pollard, Nick; Schiller, Sandra; Serrata Malfitano, Ana Paula; Thomas, Kerry; van Bruggen, Hanneke

2018-05-03

Calls for embracing the potential and responsibility of occupational therapy to address socio-political conditions that perpetuate occupational injustices have materialized in the literature. However, to reach beyond traditional frameworks informing practices, this social agenda requires the incorporation of diverse epistemological and methodological approaches to support action commensurate with social transformative goals. Our intent is to present a methodological approach that can help extend the ways of thinking or frameworks used in occupational therapy and science to support the ongoing development of practices with and for individuals and collectives affected by marginalizing conditions. We describe the epistemological and theoretical underpinnings of a methodological approach drawing on Freire and Bakhtin's work. Integrating our shared experience taking part in an example study, we discuss the unique advantages of co-generating data using two methods aligned with this approach; dialogical interviews and critical reflexivity. Key considerations when employing this approach are presented, based on its proposed epistemological and theoretical stance and our shared experiences engaging in it. A critical dialogical approach offers one way forward in expanding occupational therapy and science scholarship by promoting collaborative knowledge generation and examination of taken-for-granted understandings that shape individuals assumptions and actions.

Light-induced negative differential resistance in graphene/Si-quantum-dot tunneling diodes

PubMed Central

Lee, Kyeong Won; Jang, Chan Wook; Shin, Dong Hee; Kim, Jong Min; Kang, Soo Seok; Lee, Dae Hun; Kim, Sung; Choi, Suk-Ho; Hwang, Euyheon

2016-01-01

One of the interesing tunneling phenomena is negative differential resistance (NDR), the basic principle of resonant-tunneling diodes. NDR has been utilized in various semiconductor devices such as frequency multipliers, oscillators, relfection amplifiers, logic switches, and memories. The NDR in graphene has been also reported theoretically as well as experimentally, but should be further studied to fully understand its mechanism, useful for practical device applications. Especially, there has been no observation about light-induced NDR (LNDR) in graphene-related structures despite very few reports on the LNDR in GaAs-based heterostructures. Here, we report first observation of LNDR in graphene/Si quantum dots-embedded SiO2 (SQDs:SiO2) multilayers (MLs) tunneling diodes. The LNDR strongly depends on temperature (T) as well as on SQD size, and the T dependence is consistent with photocurrent (PC)-decay behaviors. With increasing light power, the PC-voltage curves are more structured with peak-to-valley ratios over 2 at room temperature. The physical mechanism of the LNDR, governed by resonant tunneling of charge carriers through the minibands formed across the graphene/SQDs:SiO2 MLs and by their nonresonant phonon-assisted tunneling, is discussed based on theoretical considerations. PMID:27465107

Planning a multilevel intervention to prevent hearing loss among farmworkers and managers: a systematic approach.

PubMed

Fernandez, M E; Bartholomew, L K; Alterman, T

2009-01-01

Noise-induced hearing loss (NIHL) is the second most prevalent self-reported occupational illness or injury in the U.S., and agricultural workers experience high rates of hearing loss. This article uses Intervention Mapping (IM), a systematic approach to intervention development, to make recommendations for a program to improve hearing loss protection among farmworkers and managers. Final recommendations, based on previous work in the literature on hearing loss prevention, qualitative formative research, and theoretical considerations, include a specification of a multilevel theory- and evidence-based hearing protection program for farmworkers and farm managers. Twelve performance objectives (e.g., "monitor hearing and hearing loss with regular hearing testing") are specified and crossed with six relevant determinants (knowledge and behavioral capability; perceived exposure and susceptibility and noise annoyance; outcome expectations; barriers; social influence; skills and self-efficacy) to create a highly detailed matrix of change objectives for farmworkers and for their managers. These change objectives are then grouped into five categories: two for both farmworkers and their managers (noticing exposures, taking action) and three only for the latter (surveying and planning, implementation and evaluation, and communication). Theoretical methods and practical strategies, including program materials and activities, are then delineated.

Facile fabrication of high-efficiency near-infrared absorption film with tungsten bronze nanoparticle dense layer

NASA Astrophysics Data System (ADS)

Lee, Seong Yun; Kim, Jae Young; Lee, Jun Young; Song, Ho Jun; Lee, Sangkug; Choi, Kyung Ho; Shin, Gyojic

2014-06-01

An excellent transparent film with effective absorption property in near-infrared (NIR) region based on cesium-doped tungsten oxide nanoparticles was fabricated using a facile double layer coating method via the theoretical considerations. The optical performance was evaluated; the double layer-coated film exhibited 10% transmittance at 1,000 nm in the NIR region and over 80% transmittance at 550 nm in the visible region. To optimize the selectivity, the optical spectrum of this film was correlated with a theoretical model by combining the contributions of the Mie-Gans absorption-based localized surface plasmon resonance and reflections by the interfaces of the heterogeneous layers and the nanoparticles in the film. Through comparison of the composite and double layer coating method, the difference of the nanoscale distances between nanoparticles in each layer was significantly revealed. It is worth noting that the nanodistance between the nanoparticles decreased in the double layer film, which enhanced the optical properties of the film, yielding a haze value of 1% or less without any additional process. These results are very attractive for the nanocomposite coating process, which would lead to industrial fields of NIR shielding and thermo-medical applications.

Light-induced negative differential resistance in graphene/Si-quantum-dot tunneling diodes.

PubMed

Lee, Kyeong Won; Jang, Chan Wook; Shin, Dong Hee; Kim, Jong Min; Kang, Soo Seok; Lee, Dae Hun; Kim, Sung; Choi, Suk-Ho; Hwang, Euyheon

2016-07-28

One of the interesing tunneling phenomena is negative differential resistance (NDR), the basic principle of resonant-tunneling diodes. NDR has been utilized in various semiconductor devices such as frequency multipliers, oscillators, relfection amplifiers, logic switches, and memories. The NDR in graphene has been also reported theoretically as well as experimentally, but should be further studied to fully understand its mechanism, useful for practical device applications. Especially, there has been no observation about light-induced NDR (LNDR) in graphene-related structures despite very few reports on the LNDR in GaAs-based heterostructures. Here, we report first observation of LNDR in graphene/Si quantum dots-embedded SiO2 (SQDs:SiO2) multilayers (MLs) tunneling diodes. The LNDR strongly depends on temperature (T) as well as on SQD size, and the T dependence is consistent with photocurrent (PC)-decay behaviors. With increasing light power, the PC-voltage curves are more structured with peak-to-valley ratios over 2 at room temperature. The physical mechanism of the LNDR, governed by resonant tunneling of charge carriers through the minibands formed across the graphene/SQDs:SiO2 MLs and by their nonresonant phonon-assisted tunneling, is discussed based on theoretical considerations.

A method of increasing the depth of the plastically deformed layer in the roller burnishing process

NASA Astrophysics Data System (ADS)

Kowalik, Marek; Trzepiecinski, Tomasz

2018-05-01

The subject of this paper is an analysis of the determination of the depth of the plastically deformed layer in the process of roller burnishing a shaft using a newly developed method in which a braking moment is applied to the roller. It is possible to increase the depth of the plastically deformed layer by applying the braking moment to the roller during the burnishing process. The theoretical considerations presented are based on the Hertz-Bielayev and Huber-Mises theories and permit the calculation of the depth of plastic deformation of the top layer of the burnished shaft. The theoretical analysis has been verified experimentally and using numerical calculations based on the finite element method using the Msc.MARC program. Experimental tests were carried out on ring-shaped samples made of C45 carbon steel. The samples were burnished at different values of roller force and different values of braking moment. A significant increase was found in the depth of the plastically deformed surface layer of roller burnished shafts. Usage of the phenomenon of strain hardening of steel allows the technology presented here to increase the fatigue life of the shafts.

Standard model with a complex scalar singlet: Cosmological implications and theoretical considerations

NASA Astrophysics Data System (ADS)

Chiang, Cheng-Wei; Ramsey-Musolf, Michael J.; Senaha, Eibun

2018-01-01

We analyze the theoretical and phenomenological considerations for the electroweak phase transition and dark matter in an extension of the standard model with a complex scalar singlet (cxSM). In contrast with earlier studies, we use a renormalization group improved scalar potential and treat its thermal history in a gauge-invariant manner. We find that the parameter space consistent with a strong first-order electroweak phase transition (SFOEWPT) and present dark matter phenomenological constraints is significantly restricted compared to results of a conventional, gauge-noninvariant analysis. In the simplest variant of the cxSM, recent LUX data and a SFOEWPT require a dark matter mass close to half the mass of the standard model-like Higgs boson. We also comment on various caveats regarding the perturbative treatment of the phase transition dynamics.

Novel models on fluid's variable thermo-physical properties for extensive study on convection heat and mass transfer

NASA Astrophysics Data System (ADS)

Shang, De-Yi; Zhong, Liang-Cai

2017-01-01

Our novel models for fluid's variable physical properties are improved and reported systematically in this work for enhancement of theoretical and practical value on study of convection heat and mass transfer. It consists of three models, namely (1) temperature parameter model, (2) polynomial model, and (3) weighted-sum model, respectively for treatment of temperature-dependent physical properties of gases, temperature-dependent physical properties of liquids, and concentration- and temperature-dependent physical properties of vapour-gas mixture. Two related components are proposed, and involved in each model for fluid's variable physical properties. They are basic physic property equations and theoretical similarity equations on physical property factors. The former, as the foundation of the latter, is based on the typical experimental data and physical analysis. The latter is built up by similarity analysis and mathematical derivation based on the former basic physical properties equations. These models are available for smooth simulation and treatment of fluid's variable physical properties for assurance of theoretical and practical value of study on convection of heat and mass transfer. Especially, so far, there has been lack of available study on heat and mass transfer of film condensation convection of vapour-gas mixture, and the wrong heat transfer results existed in widespread studies on the related research topics, due to ignorance of proper consideration of the concentration- and temperature-dependent physical properties of vapour-gas mixture. For resolving such difficult issues, the present novel physical property models have their special advantages.

Sensitivity of Multiangle Imaging to the Optical and Microphysical Properties of Biomass Burning Aerosols

NASA Technical Reports Server (NTRS)

Chen, Wei-Ting; Kahn, Ralph A.; Nelson, David; Yau, Kevin; Seinfeld, John H.

2008-01-01

The treatment of biomass burning (BB) carbonaceous particles in the Multiangle Imaging SpectroRadiometer (MISR) Standard Aerosol Retrieval Algorithm is assessed, and algorithm refinements are suggested, based on a theoretical sensitivity analysis and comparisons with near-coincident AERONET measurements at representative BB sites. Over the natural ranges of BB aerosol microphysical and optical properties observed in past field campaigns, patterns of retrieved Aerosol Optical Depth (AOD), particle size, and single scattering albedo (SSA) are evaluated. On the basis of the theoretical analysis, assuming total column AOD of 0.2, over a dark, uniform surface, MISR can distinguish two to three groups in each of size and SSA, except when the assumed atmospheric particles are significantly absorbing (mid-visible SSA approx.0.84), or of medium sizes (mean radius approx.0.13 pin); sensitivity to absorbing, medium-large size particles increases considerably when the assumed column AOD is raised to 0.5. MISR Research Aerosol Retrievals confirm the theoretical results, based on coincident AERONET inversions under BB-dominated conditions. When BB is externally mixed with dust in the atmosphere, dust optical model and surface reflection uncertainties, along with spatial variability, contribute to differences between the Research Retrievals and AERONET. These results suggest specific refinements to the MISR Standard Aerosol Algorithm complement of component particles and mixtures. They also highlight the importance for satellite aerosol retrievals of surface reflectance characterization, with accuracies that can be difficult to achieve with coupled surface-aerosol algorithms in some higher AOD situations.

Safety of Transcranial Direct Current Stimulation: Evidence Based Update 2016.

PubMed

Bikson, Marom; Grossman, Pnina; Thomas, Chris; Zannou, Adantchede Louis; Jiang, Jimmy; Adnan, Tatheer; Mourdoukoutas, Antonios P; Kronberg, Greg; Truong, Dennis; Boggio, Paulo; Brunoni, André R; Charvet, Leigh; Fregni, Felipe; Fritsch, Brita; Gillick, Bernadette; Hamilton, Roy H; Hampstead, Benjamin M; Jankord, Ryan; Kirton, Adam; Knotkova, Helena; Liebetanz, David; Liu, Anli; Loo, Colleen; Nitsche, Michael A; Reis, Janine; Richardson, Jessica D; Rotenberg, Alexander; Turkeltaub, Peter E; Woods, Adam J

2016-01-01

This review updates and consolidates evidence on the safety of transcranial Direct Current Stimulation (tDCS). Safety is here operationally defined by, and limited to, the absence of evidence for a Serious Adverse Effect, the criteria for which are rigorously defined. This review adopts an evidence-based approach, based on an aggregation of experience from human trials, taking care not to confuse speculation on potential hazards or lack of data to refute such speculation with evidence for risk. Safety data from animal tests for tissue damage are reviewed with systematic consideration of translation to humans. Arbitrary safety considerations are avoided. Computational models are used to relate dose to brain exposure in humans and animals. We review relevant dose-response curves and dose metrics (e.g. current, duration, current density, charge, charge density) for meaningful safety standards. Special consideration is given to theoretically vulnerable populations including children and the elderly, subjects with mood disorders, epilepsy, stroke, implants, and home users. Evidence from relevant animal models indicates that brain injury by Direct Current Stimulation (DCS) occurs at predicted brain current densities (6.3-13 A/m(2)) that are over an order of magnitude above those produced by conventional tDCS. To date, the use of conventional tDCS protocols in human trials (≤40 min, ≤4 milliamperes, ≤7.2 Coulombs) has not produced any reports of a Serious Adverse Effect or irreversible injury across over 33,200 sessions and 1000 subjects with repeated sessions. This includes a wide variety of subjects, including persons from potentially vulnerable populations. Copyright © 2016 Elsevier Inc. All rights reserved.

Safety of transcranial Direct Current Stimulation: Evidence Based Update 2016

PubMed Central

Bikson, Marom; Grossman, Pnina; Thomas, Chris; Zannou, Adantchede Louis; Jiang, Jimmy; Adnan, Tatheer; Mourdoukoutas, Antonios P; Kronberg, Greg; Truong, Dennis; Boggio, Paulo; Brunoni, André R.; Charvet, Leigh; Fregni, Felipe; Fritsch, Brita; Gillick, Bernadette; Hamilton, Roy H.; Hampstead, Benjamin M.; Jankord, Ryan; Kirton, Adam; Knotkova, Helena; Liebetanz, David; Liu, Anli; Loo, Colleen; Nitsche, Michael A.; Reis, Janine; Richardson, Jessica D.; Rotenberg, Alexander; Turkeltaub, Peter E.; Woods, Adam J.

2016-01-01

This review updates and consolidates evidence on the safety of transcranial Direct Current Stimulation (tDCS). Safety is here operationally defined by, and limited to, the absence of evidence for a Serious Adverse Effect, the criteria for which are rigorously defined. This review adopts an evidence-based approach, based on an aggregation of experience from human trials, taking care not to confuse speculation on potential hazards or lack of data to refute such speculation with evidence for risk. Safety data from animal tests for tissue damage are reviewed with systematic consideration of translation to humans. Arbitrary safety considerations are avoided. Computational models are used to relate dose to brain exposure in humans and animals. We review relevant dose-response curves and dose metrics (e.g. current, duration, current density, charge, charge density) for meaningful safety standards. Special consideration is given to theoretically vulnerable populations including children and the elderly, subjects with mood disorders, epilepsy, stroke, implants, and home users. Evidence from relevant animal models indicates that brain injury by Direct Current Stimulation (DCS) occurs at predicted brain current densities (6.3–13 A/m2) that are over an order of magnitude above those produced by conventional tDCS. To date, the use of conventional tDCS protocols in human trials (≤40 min, ≤4 mA, ≤7.2 Coulombs) has not produced any reports of a Serious Adverse Effect or irreversible injury across over 33,200 sessions and 1,000 subjects with repeated sessions. This includes a wide variety of subjects, including persons from potentially vulnerable populations. PMID:27372845

[Strategy of development, use and evaluation of the efficiency of biologically active food supplements].

PubMed

Tutel'ian, V A

1996-01-01

Analytical reviews discussed of theoretical bases and principal problems in creation, usage and evaluation of biological active food supplements (BAFS)-nutriceuticals and pharmaceuticals. Need of use the BAFS by population is grounded by data on dietary intake showing deficiency of some nutrients. Treatment and prevention of chronic diseases are other important points of BAFS using. Classification of BAFS are presented taking into consideration the resources and regulative effects. Wide using of BAFS among population is grounded by decreasing of food consumption and nutrient intake in dietary intake of modern population. Importance of BAFS in nutrition of generations of XXI century is discussed.

Blockage corrections for three-dimensional-flow closed-throat wind tunnels, with consideration of the effect of compressibility

NASA Technical Reports Server (NTRS)

Herriot, John G

1947-01-01

Theoretical blockage corrections are presented for a body of revolution and for a three-dimensional unswept wing in a circular or rectangular wind tunnel. The theory takes account of the effects of the wake and of the compressibility of the fluid, and is based on the assumption that the dimensions of the model are small in comparison with those of the tunnel throat. Formulas are given for correcting a number of the quantities, such as dynamic pressure and Mach number, measured in wind-tunnel tests. The report presents a summary and unification of the existing literature on the subject.

Advanced turboprop noise prediction based on recent theoretical results

NASA Technical Reports Server (NTRS)

Farassat, F.; Padula, S. L.; Dunn, M. H.

1987-01-01

The development of a high speed propeller noise prediction code at Langley Research Center is described. The code utilizes two recent acoustic formulations in the time domain for subsonic and supersonic sources. The structure and capabilities of the code are discussed. Grid size study for accuracy and speed of execution on a computer is also presented. The code is tested against an earlier Langley code. Considerable increase in accuracy and speed of execution are observed. Some examples of noise prediction of a high speed propeller for which acoustic test data are available are given. A brisk derivation of formulations used is given in an appendix.

On the tumbling toast problem

NASA Astrophysics Data System (ADS)

Borghi, Riccardo

2012-09-01

A didactical revisitation of the so-called tumbling toast problem is presented here. The numerical solution of the related Newton's equations has been found in the space domain, without resorting to the complete time-based law of motion, with a considerable reduction of the mathematical complexity of the problem. This could allow the effect of the different physical mechanisms ruling the overall dynamics to be appreciated in a more transparent way, even by undergraduates. Moreover, the availability from the literature of experimental investigations carried out on tumbling toast allows us to propose different theoretical models of growing complexity in order to show the corresponding improvement of the agreement between theory and observation.

Toward a social justice theory of demographic transition: lessons from India's Kerala State.

PubMed

Ratcliffe, J W

1983-06-01

Recent research evidence, which suggests that observed demographic trends and patterns are largely consequences of broad structural changes in society, has raised serious doubts about the validity of traditional demographic theory and the framework for action it has generated. This theoretical essay 1st recasts classical demographic transition theory in general systems terms in order to make it consistent with the evidence and to place the processes of fertility and mortality in a larger social context. The demographic transition experience of Kerala State, India is then recounted to provide a concrete example of the demographic response in society to structural reforms based primarily on equity considerations.

Social Learning Theory and Behavioral Therapy: Considering Human Behaviors within the Social and Cultural Context of Individuals and Families.

PubMed

McCullough Chavis, Annie

2011-01-01

This article examines theoretical thoughts of social learning theory and behavioral therapy and their influences on human behavior within a social and cultural context. The article utilizes two case illustrations with applications for consumers. It points out the abundance of research studies concerning the effectiveness of social learning theory, and the paucity of research studies regarding effectiveness and evidence-based practices with diverse groups. Providing a social and cultural context in working with diverse groups with reference to social learning theory adds to the literature for more cultural considerations in adapting the theory to women, African Americans, and diverse groups.

Some remarks on the compatibility between determinism and unpredictability.

PubMed

Franceschelli, Sara

2012-09-01

Determinism and unpredictability are compatible since deterministic flows can produce, if sensitive to initial conditions, unpredictable behaviors. Within this perspective, the notion of scenario to chaos transition offers a new form of predictability for the behavior of sensitive to initial condition systems under the variation of a control parameter. In this paper I first shed light on the genesis of this notion, based on a dynamical systems approach and on considerations of structural stability. I then suggest a link to the figure of epigenetic landscape, partially inspired by a dynamical systems perspective, and offering a theoretical framework to apprehend developmental noise. Copyright © 2012 Elsevier Ltd. All rights reserved.

Diversification strategy and performance: implications for health services research.

PubMed

Rivers, P A; Glover, S H; Munchus, G

1999-01-01

Health care represents a promising area of research due to its uniqueness. In recent years, considerable progress has been made in diversification strategy and performance research but not the study of health services strategy research. This article reviews diversification strategy and performance in health services domains. Adopting Datta, Rajagopalan, and Rasheed's (1991) framework, the authors evaluate the theoretical and empirical contributions of this research. The limitations and theoretical implications of these efforts are also explored.

Creating restorative settings: inclusive design considerations

Treesearch

David Kamp

2009-01-01

One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

Project : semi-autonomous parking for enhanced safety and efficiency.

DOT National Transportation Integrated Search

2016-04-01

Index coding, a coding formulation traditionally analyzed in the theoretical computer science and : information theory communities, has received considerable attention in recent years due to its value in : wireless communications and networking probl...

How Is Working Memory Training Likely to Influence Academic Performance? Current Evidence and Methodological Considerations.

PubMed

Bergman Nutley, Sissela; Söderqvist, Stina

2017-01-01

Working memory (WM) is one of our core cognitive functions, allowing us to keep information in mind for shorter periods of time and then work with this information. It is the gateway that information has to pass in order to be processed consciously. A well-functioning WM is therefore crucial for a number of everyday activities including learning and academic performance (Gathercole et al., 2003; Bull et al., 2008), which is the focus of this review. Specifically, we will review the research investigating whether improving WM capacity using Cogmed WM training can lead to improvements on academic performance. Emphasis is given to reviewing the theoretical principles upon which such investigations rely, in particular the complex relation between WM and mathematical and reading abilities during development and how these are likely to be influenced by training. We suggest two possible routes in which training can influence academic performance, one through an effect on learning capacity which would thus be evident with time and education, and one through an immediate effect on performance on reading and mathematical tasks. Based on the theoretical complexity described we highlight some methodological issues that are important to take into consideration when designing and interpreting research on WM training and academic performance, but that are nonetheless often overlooked in the current research literature. Finally, we will provide some suggestions for future research for advancing the understanding of WM training and its potential role in supporting academic attainment.

Exact consideration of data redundancies for spiral cone-beam CT

NASA Astrophysics Data System (ADS)

Lauritsch, Guenter; Katsevich, Alexander; Hirsch, Michael

2004-05-01

In multi-slice spiral computed tomography (CT) there is an obvious trend in adding more and more detector rows. The goals are numerous: volume coverage, isotropic spatial resolution, and speed. Consequently, there will be a variety of scan protocols optimizing clinical applications. Flexibility in table feed requires consideration of data redundancies to ensure efficient detector usage. Until recently this was achieved by approximate reconstruction algorithms only. However, due to the increasing cone angles there is a need of exact treatment of the cone beam geometry. A new, exact and efficient 3-PI algorithm for considering three-fold data redundancies was derived from a general, theoretical framework based on 3D Radon inversion using Grangeat's formula. The 3-PI algorithm possesses a simple and efficient structure as the 1-PI method for non-redundant data previously proposed. Filtering is one-dimensional, performed along lines with variable tilt on the detector. This talk deals with a thorough evaluation of the performance of the 3-PI algorithm in comparison to the 1-PI method. Image quality of the 3-PI algorithm is superior. The prominent spiral artifacts and other discretization artifacts are significantly reduced due to averaging effects when taking into account redundant data. Certainly signal-to-noise ratio is increased. The computational expense is comparable even to that of approximate algorithms. The 3-PI algorithm proves its practicability for applications in medical imaging. Other exact n-PI methods for n-fold data redundancies (n odd) can be deduced from the general, theoretical framework.

Clustering, randomness and regularity in cloud fields. I - Theoretical considerations. II - Cumulus cloud fields

NASA Technical Reports Server (NTRS)

Weger, R. C.; Lee, J.; Zhu, Tianri; Welch, R. M.

1992-01-01

The current controversy existing in reference to the regularity vs. clustering in cloud fields is examined by means of analysis and simulation studies based upon nearest-neighbor cumulative distribution statistics. It is shown that the Poisson representation of random point processes is superior to pseudorandom-number-generated models and that pseudorandom-number-generated models bias the observed nearest-neighbor statistics towards regularity. Interpretation of this nearest-neighbor statistics is discussed for many cases of superpositions of clustering, randomness, and regularity. A detailed analysis is carried out of cumulus cloud field spatial distributions based upon Landsat, AVHRR, and Skylab data, showing that, when both large and small clouds are included in the cloud field distributions, the cloud field always has a strong clustering signal.

Metasurface-based anti-reflection coatings at optical frequencies

NASA Astrophysics Data System (ADS)

Monti, Alessio; Alù, Andrea; Toscano, Alessandro; Bilotti, Filiberto

2018-05-01

In this manuscript, we propose a metasurface approach for the reduction of electromagnetic reflection from an arbitrary air‑dielectric interface. The proposed technique exploits the exotic optical response of plasmonic nanoparticles to achieve complete cancellation of the field reflected by a dielectric substrate by means of destructive interference. Differently from other, earlier anti-reflection approaches based on nanoparticles, our design scheme is supported by a simple transmission-line formulation that allows a closed-form characterization of the anti-reflection performance of a nanoparticle array. Furthermore, since the working principle of the proposed devices relies on an average effect that does not critically depend on the array geometry, our approach enables low-cost production and easy scalability to large sizes. Our theoretical considerations are supported by full-wave simulations confirming the effectiveness of this design principle.

Thermal shock fracture in cross-ply fibre-reinforced ceramic-matrix composites

NASA Astrophysics Data System (ADS)

Kastritseas, C.; Smith, P. A.; Yeomans, J. A.

2010-11-01

The onset of matrix cracking due to thermal shock in a range of simple and multi-layer cross-ply laminates comprising a calcium aluminosilicate (CAS) matrix reinforced with Nicalon® fibres is investigated analytically. A comprehensive stress analysis under conditions of thermal shock, ignoring transient effects, is performed and fracture criteria based on either a recently derived model for the thermal shock resistance of unidirectional Nicalon®/glass ceramic-matrix composites or fracture mechanics considerations are formulated. The effect of material thickness on the apparent thermal shock resistance is also modelled. Comparison with experimental results reveals that the accuracy of the predictions is satisfactory and the reasons for some discrepancies are discussed. In addition, a theoretical argument based on thermal shock theory is formulated to explain the observed cracking patterns.

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

Da Rio, Nicola; Robberto, Massimo, E-mail: ndario@rssd.esa.int

We present the Tool for Astrophysical Data Analysis (TA-DA), a new software aimed to greatly simplify and improve the analysis of stellar photometric data in comparison with theoretical models, and allow the derivation of stellar parameters from multi-band photometry. Its flexibility allows one to address a number of such problems: from the interpolation of stellar models, or sets of stellar physical parameters in general, to the computation of synthetic photometry in arbitrary filters or units; from the analysis of observed color-magnitude diagrams to a Bayesian derivation of stellar parameters (and extinction) based on multi-band data. TA-DA is available as amore » pre-compiled Interactive Data Language widget-based application; its graphical user interface makes it considerably user-friendly. In this paper, we describe the software and its functionalities.« less

[Education and competences for the Brazilian Unified Health System (SUS): is it possible to find alternatives to the logic of late capitalism?].

PubMed

Siqueira-Batista, Rodrigo; Gomes, Andréia Patrícia; Albuquerque, Verônica Santos; Cavalcanti, Felipe de Oliveira Lopes; Cotta, Rosângela Minardi Mitre

2013-01-01

The transformations that have revolutionized the labor market in contemporary society make it necessary to think of new alternatives for training health care professionals, thereby establishing a new approach to the health problems of individuals and collectives. Based on these considerations, this paper sets out to discuss training in health--based on the concept of competence--with a focus on education for the Brazilian Unified Health System (SUS), using attempts to analyze and propose an alternative to the system entrenched in the logic of late capitalism as a theoretical benchmark. It is thus a reflection on the subject, correlating theory and praxis, in constant and relentless movement of construction, deconstruction and (re)construction of propositions.

Synthesis, Characterization, and Theoretical Considerations of 1,2-bis(oxyamino)ethane Salts

NASA Technical Reports Server (NTRS)

Crake, Greg; Hawkins, Tom; Hall, Leslie; Tollison, Kerri; Brand, Adam

2003-01-01

The synthesis, characterization, theoretical calculations, and safety studies of energetic salts of 1,2- bis(oxyamino) ethane, (H2N-O-CH2-CH2-O-NH2), were carried out. The salts were characterized by vibrational (infrared, Raman), multinuclear nmr studies (1H, 13C), differential scanning calorimetry (DSC); elemental analysis; and initial safety testing (impact and friction sensitivity) . Theoretical calculations on the neutral, monoprotonated, and doubly protonated species of ethylene bisoxyamine were carried out using xxxx level of theory for the lowest energy structure and these theoretical results compared with the experimentally observed bond distances and vibrational (ir, Raman) frequency values. The single crystal X-ray diffraction study was carried out on the mono-perchlorate salt revealing a high degree of hydrogen bonding with an unexpected structure.

Theoretical study for aerial image intensity in resist in high numerical aperture projection optics and experimental verification with one-dimensional patterns

NASA Astrophysics Data System (ADS)

Shibuya, Masato; Takada, Akira; Nakashima, Toshiharu

2016-04-01

In optical lithography, high-performance exposure tools are indispensable to obtain not only fine patterns but also preciseness in pattern width. Since an accurate theoretical method is necessary to predict these values, some pioneer and valuable studies have been proposed. However, there might be some ambiguity or lack of consensus regarding the treatment of diffraction by object, incoming inclination factor onto image plane in scalar imaging theory, and paradoxical phenomenon of the inclined entrance plane wave onto image in vector imaging theory. We have reconsidered imaging theory in detail and also phenomenologically resolved the paradox. By comparing theoretical aerial image intensity with experimental pattern width for one-dimensional pattern, we have validated our theoretical consideration.

Assessment of alternative disposal methods to reduce greenhouse gas emissions from municipal solid waste in India.

PubMed

Yedla, Sudhakar; Sindhu, N T

2016-06-01

Open dumping, the most commonly practiced method of solid waste disposal in Indian cities, creates serious environment and economic challenges, and also contributes significantly to greenhouse gas emissions. The present article attempts to analyse and identify economically effective ways to reduce greenhouse gas emissions from municipal solid waste. The article looks at the selection of appropriate methods for the control of methane emissions. Multivariate functional models are presented, based on theoretical considerations as well as the field measurements to forecast the greenhouse gas mitigation potential for all the methodologies under consideration. Economic feasibility is tested by calculating the unit cost of waste disposal for the respective disposal process. The purpose-built landfill system proposed by Yedla and Parikh has shown promise in controlling greenhouse gas and saving land. However, these studies show that aerobic composting offers the optimal method, both in terms of controlling greenhouse gas emissions and reducing costs, mainly by requiring less land than other methods. © The Author(s) 2016.

Experimental investigation of forced convective heat transfer performance in nanofluids of Al2O3/water and CuO/water in a serpentine shaped micro channel heat sink

NASA Astrophysics Data System (ADS)

Sivakumar, A.; Alagumurthi, N.; Senthilvelan, T.

2016-07-01

The microchannels are device used to remove high heat fluxes from smaller area. In this experimental research work the heat transfer performance of nanofluids of Al2O3/water and CuO/water were compared. The important character of such fluids is the enhanced thermal conductivity, in comparison with base fluid without considerable alteration in physical and chemical properties. The effect of forced convective heat transfer coefficient was calculated using serpentine shaped microchannel heat exchanger. Furthermore we calculated the forced convective heat transfer coefficient of the nanofluids using theoretical correlations in order to compare the results with the experimental data. The heat transfer coefficient for different particle concentration and temperature were analysed using forced convection heat transfer using nanofluids. The findings indicate considerable enhancement in convective heat transfer coefficient of the nanofluids as compared to the basefluid. The results also shows that CuO/water nanofluid has increased heat transfer coefficient compared with Al2O3/water and base fluids. Moreover the experimental results indicate there is increased forced convective heat transfer coefficient with the increase in nano particle concentration.

Meta-analysis on the effectiveness of team-based learning on medical education in China.

PubMed

Chen, Minjian; Ni, Chunhui; Hu, Yanhui; Wang, Meilin; Liu, Lu; Ji, Xiaoming; Chu, Haiyan; Wu, Wei; Lu, Chuncheng; Wang, Shouyu; Wang, Shoulin; Zhao, Liping; Li, Zhong; Zhu, Huijuan; Wang, Jianming; Xia, Yankai; Wang, Xinru

2018-04-10

Team-based learning (TBL) has been adopted as a new medical pedagogical approach in China. However, there are no studies or reviews summarizing the effectiveness of TBL on medical education. This study aims to obtain an overall estimation of the effectiveness of TBL on outcomes of theoretical teaching of medical education in China. We retrieved the studies from inception through December, 2015. Chinese National Knowledge Infrastructure, Chinese Biomedical Literature Database, Chinese Wanfang Database, Chinese Scientific Journal Database, PubMed, EMBASE and Cochrane Database were searched. The quality of included studies was assessed by the Newcastle-Ottawa scale. Standardized mean difference (SMD) was applied for the estimation of the pooled effects. Heterogeneity assumption was detected by I 2 statistics, and was further explored by meta-regression analysis. A total of 13 articles including 1545 participants eventually entered into the meta-analysis. The quality scores of these studies ranged from 6 to 10. Altogether, TBL significantly increased students' theoretical examination scores when compared with lecture-based learning (LBL) (SMD = 2.46, 95% CI: 1.53-3.40). Additionally, TBL significantly increased students' learning attitude (SMD = 3.23, 95% CI: 2.27-4.20), and learning skill (SMD = 2.70, 95% CI: 1.33-4.07). The meta-regression results showed that randomization, education classification and gender diversity were the factors that caused heterogeneity. TBL in theoretical teaching of medical education seems to be more effective than LBL in improving the knowledge, attitude and skill of students in China, providing evidence for the implement of TBL in medical education in China. The medical schools should implement TBL with the consideration on the practical teaching situations such as students' education level.

Electric dipole moments of the fluorescent probes Prodan and Laurdan: experimental and theoretical evaluations.

PubMed

Vequi-Suplicy, Cíntia C; Coutinho, Kaline; Lamy, M Teresa

2014-03-01

Several experimental and theoretical approaches can be used for a comprehensive understanding of solvent effects on the electronic structure of solutes. In this review, we revisit the influence of solvents on the electronic structure of the fluorescent probes Prodan and Laurdan, focusing on their electric dipole moments. These biologically used probes were synthesized to be sensitive to the environment polarity. However, their solvent-dependent electronic structures are still a matter of discussion in the literature. The absorption and emission spectra of Prodan and Laurdan in different solvents indicate that the two probes have very similar electronic structures in both the ground and excited states. Theoretical calculations confirm that their electronic ground states are very much alike. In this review, we discuss the electric dipole moments of the ground and excited states calculated using the widely applied Lippert-Mataga equation, using both spherical and spheroid prolate cavities for the solute. The dimensions of the cavity were found to be crucial for the calculated dipole moments. These values are compared to those obtained by quantum mechanics calculations, considering Prodan in vacuum, in a polarizable continuum solvent, and using a hybrid quantum mechanics-molecular mechanics methodology. Based on the theoretical approaches it is evident that the Prodan dipole moment can change even in the absence of solute-solvent-specific interactions, which is not taken into consideration with the experimental Lippert-Mataga method. Moreover, in water, for electric dipole moment calculations, it is fundamental to consider hydrogen-bonded molecules.

Can a theoretical framework help to embed alcohol screening and brief interventions in an endoscopy day-unit?

PubMed

O'Neill, G; Masson, S; Bewick, L; Doyle, J; McGovern, R; Stoker, E; Wright, H; Newbury-Birch, D

2016-01-01

The National Institute for Health Care and Excellence recommend that alcohol screening and brief intervention (ASBI) should be routinely implemented in secondary care. This study used theoretical frameworks to understand how health professionals can be supported to adapt their behaviour and clinical practice. Staff training and support was conducted using theoretical frameworks. A 12-week study, delivering ASBI was carried out as part of routine practice in an endoscopy day-unit. Anonymised patient data were collected using the Alcohol Use Disorders Identification Tool (AUDIT) and whether patients received a brief intervention. Staff completed the Shortened Alcohol and Alcohol Problems Perceptions Questionnaire at three time points and took part in a focus group both pre and post study. For staff, levels or role adequacy, role legitimacy, motivation to discuss alcohol, security in their role, job satisfaction and commitment to working with patients who drink increased during the time of the study. 1598 individual patients were seen in the department in the timeframe. Of these, 1180 patients were approached (74%); 18% (n=207) of patients were AUDIT positive. This study has shown that it is possible to reach a high number of patients in a busy hospital out-patient department and deliver ASBI by working with staff using theoretical frameworks for training. Embedding evidence-based public health interventions into routine clinical environments is complex. The social system in which professionals operate requires consideration alongside individual professionals' real and perceived barriers and facilitators to change.

Merging Theoretical Models and Therapy Approaches in the Context of Internet Gaming Disorder: A Personal Perspective.

PubMed

Young, Kimberly S; Brand, Matthias

2017-01-01

Although, it is not yet officially recognized as a clinical entity which is diagnosable, Internet Gaming Disorder (IGD) has been included in section III for further study in the DSM-5 by the American Psychiatric Association (APA, 2013). This is important because there is increasing evidence that people of all ages, in particular teens and young adults, are facing very real and sometimes very severe consequences in daily life resulting from an addictive use of online games. This article summarizes general aspects of IGD including diagnostic criteria and arguments for the classification as an addictive disorder including evidence from neurobiological studies. Based on previous theoretical considerations and empirical findings, this paper examines the use of one recently proposed model, the Interaction of Person-Affect-Cognition-Execution (I-PACE) model, for inspiring future research and for developing new treatment protocols for IGD. The I-PACE model is a theoretical framework that explains symptoms of Internet addiction by looking at interactions between predisposing factors, moderators, and mediators in combination with reduced executive functioning and diminished decision making. Finally, the paper discusses how current treatment protocols focusing on Cognitive-Behavioral Therapy for Internet addiction (CBT-IA) fit with the processes hypothesized in the I-PACE model.

Merging Theoretical Models and Therapy Approaches in the Context of Internet Gaming Disorder: A Personal Perspective

PubMed Central

Young, Kimberly S.; Brand, Matthias

2017-01-01

Although, it is not yet officially recognized as a clinical entity which is diagnosable, Internet Gaming Disorder (IGD) has been included in section III for further study in the DSM-5 by the American Psychiatric Association (APA, 2013). This is important because there is increasing evidence that people of all ages, in particular teens and young adults, are facing very real and sometimes very severe consequences in daily life resulting from an addictive use of online games. This article summarizes general aspects of IGD including diagnostic criteria and arguments for the classification as an addictive disorder including evidence from neurobiological studies. Based on previous theoretical considerations and empirical findings, this paper examines the use of one recently proposed model, the Interaction of Person-Affect-Cognition-Execution (I-PACE) model, for inspiring future research and for developing new treatment protocols for IGD. The I-PACE model is a theoretical framework that explains symptoms of Internet addiction by looking at interactions between predisposing factors, moderators, and mediators in combination with reduced executive functioning and diminished decision making. Finally, the paper discusses how current treatment protocols focusing on Cognitive-Behavioral Therapy for Internet addiction (CBT-IA) fit with the processes hypothesized in the I-PACE model. PMID:29104555

Use of theoretical waste inventories in planning and monitoring of hazardous waste management systems.

PubMed

Yilmaz, Ozge; Can, Zehra S; Toroz, Ismail; Dogan, Ozgur; Oncel, Salim; Alp, Emre; Dilek, Filiz B; Karanfil, Tanju; Yetis, Ulku

2014-08-01

Hazardous waste (HW) generation information is an absolute necessity for ensuring the proper planning, implementation, and monitoring of any waste management system. Unfortunately, environmental agencies in developing countries face difficulties in gathering data directly from the creators of such wastes. It is possible, however, to construct theoretical HW inventories using the waste generation factors (WGFs). The objective of this study was to develop a complete nationwide HW inventory of Turkey that relies on nation-specific WGFs to support management activities of the Turkish Ministry of Environment and Urbanization (MoEU). Inventory studies relied on WGFs from: (a) the literature and (b) field studies and analysis of waste declarations reflecting country-specific industrial practices. Moreover, new tools were introduced to the monitoring infrastructure of MoEU to obtain a comprehensive waste generation data set. Through field studies and a consideration of country specific conditions, it was possible to more thoroughly elucidate HW generation trends in Turkey, a method that was deemed superior to other alternatives. Declaration and literature based WGFs also proved most helpful in supplementing field observations that could not always be conducted. It was determined that these theoretical inventories could become valuable assets in supporting regulating agencies in developing countries for a more thorough implementation of HW management systems. © The Author(s) 2014.

Effect of Reynolds number variation on aerodynamics of a hydrogen-fueled transport concept at Mach 6

NASA Technical Reports Server (NTRS)

Penland, Jim A.; Marcum, Don C., Jr.

1987-01-01

Two separate tests have been made on the same blended wing-body hydrogen-fueled transport model at a Mach number of about 6 and a range of Reynolds number (based on theoretical body length) of 1.577 to 55.36 X 10 to the 6th power. The results of these tests, made in a conventional hypersonic blowdown tunnel and a hypersonic shock tunnel, are presented through a range of angle of attack from -1 to 8 deg, with an extended study at a constant angle of attack of 3 deg. The model boundary layer flow appeared to be predominately turbulent except for the low Reynolds number shock tunnel tests. Model wall temperatures varied considerably; the blowdown tunnel varied from about 255 F to 340 F, whereas the shock tunnel had a constant 70 F model wall temperature. The experimental normal-force coefficients were essentially independent of Reynolds number. A current theoretical computer program was used to study the effect of Reynolds number. Theoretical predictions of normal-force coefficients were good, particularly at anticipated cruise angles of attack, that is 2 to 5 deg. Axial-force coefficients were generally underestimated for the turbulent skin friction conditions, and pitching-moment coefficients could not be predicted reliably.

Warming alters the metabolic balance of ecosystems

PubMed Central

Yvon-Durocher, Gabriel; Jones, J. Iwan; Trimmer, Mark; Woodward, Guy; Montoya, Jose M.

2010-01-01

The carbon cycle modulates climate change, via the regulation of atmospheric CO2, and it represents one of the most important services provided by ecosystems. However, considerable uncertainties remain concerning potential feedback between the biota and the climate. In particular, it is unclear how global warming will affect the metabolic balance between the photosynthetic fixation and respiratory release of CO2 at the ecosystem scale. Here, we present a combination of experimental field data from freshwater mesocosms, and theoretical predictions derived from the metabolic theory of ecology to investigate whether warming will alter the capacity of ecosystems to absorb CO2. Our manipulative experiment simulated the temperature increases predicted for the end of the century and revealed that ecosystem respiration increased at a faster rate than primary production, reducing carbon sequestration by 13 per cent. These results confirmed our theoretical predictions based on the differential activation energies of these two processes. Using only the activation energies for whole ecosystem photosynthesis and respiration we provide a theoretical prediction that accurately quantified the precise magnitude of the reduction in carbon sequestration observed experimentally. We suggest the combination of whole-ecosystem manipulative experiments and ecological theory is one of the most promising and fruitful research areas to predict the impacts of climate change on key ecosystem services. PMID:20513719

[Some insights on the influence of socioeconomic factors on migratory movements].

PubMed

Gordillo, J

1981-01-01

A theoretical approach to the study of migration in Ecuador is presented. Consideration is also given to the relationships among migration, mortality, fertility, and employment and to the policy implications of these relationships.

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

Finzi, S.; Marchetti, C.; Renzoni, R.

The first of four reports on the design of a plant for producing 99.75 mole% D/sub 2/O from preconcentrated solutions is presented. The isotopic and chemicophysical design is treated, all the necessary theoretical considerations for the calculations being given. (T.R.H.)

Theoretical and Methodological Considerations in Cross-Generational Research on Parenting and Child Aggressive Behavior

PubMed Central

Dubow, Eric F.; Huesmann, L. Rowell; Boxer, Paul

2015-01-01

The four studies in this special issue represent important advances in research on the intergenerational transmission of aggressive behavior. In this commentary, we review the key features and findings of these studies, as well as our own cross-generational study of aggression, the Columbia County Longitudinal Study. Next, we consider important theoretical issues (e.g., defining and operationalizing “aggression” and “parenting”; assessing reciprocal effects of parenting and child aggression; identifying the ages at which aggression should be assessed across generations; broadening the investigation of contextual and individual factors). We then discuss several methodological issues (e.g., determining the most informative measurement intervals for assessing prospective effects; sampling considerations; measuring potential moderating and mediating variables that might explain cross-generational continuities and discontinuities in parenting and aggression). Finally, we raise implications of cross-generational research for designing interventions targeting the reduction and prevention of child aggression. PMID:12735400

Quantitative morphology of the vascularisation of organs: A stereological approach illustrated using the cardiac circulation.

PubMed

Mühlfeld, Christian

2014-01-01

The vasculature of the heart is able to adapt to various physiological and pathological stimuli and its failure to do so is well-reflected by the great impact of ischaemic heart disease on personal morbidity and mortality and on the health care systems of industrial countries. Studies on physiological or genetic interventions as well as therapeutic angiogenesis rely on quantitative data to characterize the effects in a statistically robust way. The gold standard for obtaining quantitative morphological data is design-based stereology which allows the estimation of volume, surface area, length and number of blood vessels as well as their thickness, diameter or wall composition. Unfortunately, the use of stereological methods for this purpose is still rare. One of the reasons for this is the fact that the transfer of the theoretical foundations into laboratory practice requires a remarkable amount of considerations before touching the first piece of tissue. These considerations, however, are often based on already acquired experience and are usually not dealt with in stereological review articles. The present article therefore delineates the procedures for estimating the most important characteristics of the cardiac vasculature and highlights potential problems and their practical solutions. Worked examples are used to illustrate the methods and provide examples of the calculations. Hopefully, the considerations and examples contained herein will provide researchers in this field with the necessary equipment to add stereological methods to their study designs. Copyright © 2012 Elsevier GmbH. All rights reserved.

The Role of Empowerment in a School-Based Community Service Program with Inner-City, Minority Youth

PubMed Central

Gullan, Rebecca L.; Power, Thomas J.; Leff, Stephen S.

2014-01-01

Despite considerable fiscal and structural support for youth service programs, research has not demonstrated consistent outcomes across participants or programs, suggesting the need to identify critical program processes. The present study addresses this need through preliminary examination of the role of program empowerment in promoting positive identity development in inner-city, African American youth participating in a pilot school-based service program. Results suggest that participants who experienced the program as empowering experienced increases in self-efficacy, sense of civic responsibility, and ethnic identity, over and above general engagement and enjoyment of the program. Preliminary exploration of differences based on participant gender suggests that some results may be stronger and more consistent for males than females. These findings provide preliminary support for the importance of theoretically grounded program processes in producing positive outcomes for youth service participants. PMID:25104875

Scale-invariant entropy-based theory for dynamic ordering

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

Mahulikar, Shripad P., E-mail: spm@iitmandi.ac.in, E-mail: spm@aero.iitb.ac.in; Department of Aerospace Engineering, Indian Institute of Technology Bombay, Mumbai 400076; Kumari, Priti

2014-09-01

Dynamically Ordered self-organized dissipative structure exists in various forms and at different scales. This investigation first introduces the concept of an isolated embedding system, which embeds an open system, e.g., dissipative structure and its mass and/or energy exchange with its surroundings. Thereafter, scale-invariant theoretical analysis is presented using thermodynamic principles for Order creation, existence, and destruction. The sustainability criterion for Order existence based on its structured mass and/or energy interactions with the surroundings is mathematically defined. This criterion forms the basis for the interrelationship of physical parameters during sustained existence of dynamic Order. It is shown that the sufficient conditionmore » for dynamic Order existence is approached if its sustainability criterion is met, i.e., its destruction path is blocked. This scale-invariant approach has the potential to unify the physical understanding of universal dynamic ordering based on entropy considerations.« less

Visibility Graph Based Time Series Analysis.

PubMed

Stephen, Mutua; Gu, Changgui; Yang, Huijie

2015-01-01

Network based time series analysis has made considerable achievements in the recent years. By mapping mono/multivariate time series into networks, one can investigate both it's microscopic and macroscopic behaviors. However, most proposed approaches lead to the construction of static networks consequently providing limited information on evolutionary behaviors. In the present paper we propose a method called visibility graph based time series analysis, in which series segments are mapped to visibility graphs as being descriptions of the corresponding states and the successively occurring states are linked. This procedure converts a time series to a temporal network and at the same time a network of networks. Findings from empirical records for stock markets in USA (S&P500 and Nasdaq) and artificial series generated by means of fractional Gaussian motions show that the method can provide us rich information benefiting short-term and long-term predictions. Theoretically, we propose a method to investigate time series from the viewpoint of network of networks.

Color characterization of coatings with diffraction pigments.

PubMed

Ferrero, A; Bernad, B; Campos, J; Perales, E; Velázquez, J L; Martínez-Verdú, F M

2016-10-01

Coatings with diffraction pigments present high iridescence, which needs to be characterized in order to describe their appearance. The spectral bidirectional reflectance distribution functions (BRDFs) of six coatings with SpectraFlair diffraction pigments were measured using the robot-arm-based goniospectrophotometer GEFE, designed and developed at CSIC. Principal component analysis has been applied to study the coatings of BRDF data. From data evaluation and based on theoretical considerations, we propose a relevant geometric factor to study the spectral reflectance and color gamut variation of coatings with diffraction pigments. At fixed values of this geometric factor, the spectral BRDF component due to diffraction is almost constant. Commercially available portable goniospectrophotometers, extensively used in several industries (automotive and others), should be provided with more aspecular measurement angles to characterize the complex reflectance of goniochromatic coatings based on diffraction pigments, but they would not require either more than one irradiation angle or additional out-of-plane geometries.

Quality factor analysis for aberrated laser beam

NASA Astrophysics Data System (ADS)

Ghafary, B.; Alavynejad, M.; Kashani, F. D.

2006-12-01

The quality factor of laser beams has attracted considerable attention and some different approaches have been reported to treat the problem. In this paper we analyze quality factor of laser beam and compare the effect of different aberrations on beam quality by expanding pure phase term of wavefront in terms of Zernike polynomials. Also we analyze experimentally the change of beam quality for different Astigmatism aberrations, and compare theoretical results with experimentally results. The experimental and theoretical results are in good agreement.

[AVIATION MEDICINE: THEORETICAL CONCEPTS AND FOCAL FUNDAMENTAL AND PRACTICAL ISSUES (for the 80th anniversary of the Research Test Center of Aerospace Medicine and Military Ergonomics)].

PubMed

Zhdanko, I M; Pisarev, A A; Vorona, A A; Lapa, V V; Khomenko, M N

2015-01-01

The article discloses postulates of theoretical concepts that make the methodological basis for addressing the real-world aviation medicine challenges of humanizing aviator's environment, labor content and means, and health and performance maintenance. Under consideration are focal fundamental and practical issues arising with the technological progress in aviation and dealt with at the AF CRI Research Test Center of Aerospace Medicine and Military Ergonomics.

Real-time feedback on nonverbal clinical communication. Theoretical framework and clinician acceptance of ambient visual design.

PubMed

Hartzler, A L; Patel, R A; Czerwinski, M; Pratt, W; Roseway, A; Chandrasekaran, N; Back, A

2014-01-01

This article is part of the focus theme of Methods of Information in Medicine on "Pervasive Intelligent Technologies for Health". Effective nonverbal communication between patients and clinicians fosters both the delivery of empathic patient-centered care and positive patient outcomes. Although nonverbal skill training is a recognized need, few efforts to enhance patient-clinician communication provide visual feedback on nonverbal aspects of the clinical encounter. We describe a novel approach that uses social signal processing technology (SSP) to capture nonverbal cues in real time and to display ambient visual feedback on control and affiliation--two primary, yet distinct dimensions of interpersonal nonverbal communication. To examine the design and clinician acceptance of ambient visual feedback on nonverbal communication, we 1) formulated a model of relational communication to ground SSP and 2) conducted a formative user study using mixed methods to explore the design of visual feedback. Based on a model of relational communication, we reviewed interpersonal communication research to map nonverbal cues to signals of affiliation and control evidenced in patient-clinician interaction. Corresponding with our formulation of this theoretical framework, we designed ambient real-time visualizations that reflect variations of affiliation and control. To explore clinicians' acceptance of this visual feedback, we conducted a lab study using the Wizard-of-Oz technique to simulate system use with 16 healthcare professionals. We followed up with seven of those participants through interviews to iterate on the design with a revised visualization that addressed emergent design considerations. Ambient visual feedback on non- verbal communication provides a theoretically grounded and acceptable way to provide clinicians with awareness of their nonverbal communication style. We provide implications for the design of such visual feedback that encourages empathic patient-centered communication and include considerations of metaphor, color, size, position, and timing of feedback. Ambient visual feedback from SSP holds promise as an acceptable means for facilitating empathic patient-centered nonverbal communication.

Comparing responses to horticultural-based and traditional activities in dementia care programs.

PubMed

Jarrott, Shannon E; Gigliotti, Christina M

2010-12-01

Engaging persons with dementia in meaningful activities supports well-being; however, care staff are challenged to implement age- and ability-appropriate activities in a group setting. We compared a randomly assigned treatment group, who received horticultural therapy-based (HT-based) programming to a comparison group, who engaged in traditional activities (TA) programming, on engagement and affect. Horticultural therapy-based programming was implemented twice weekly at 4 treatment sites for 6 weeks, while regular TA were observed at comparison sites. Results revealed no differences between groups on affective domains. Levels of adaptive behavior differed between the groups, with the treatment group demonstrating higher levels of active, passive, and other engagement and the comparison group demonstrating higher levels of self-engagement. Our results highlight the value of HT-based programs and the importance of simultaneously capturing participants' affective and behavioral responses. Theoretical and practical considerations about the facilitation of and context in which the programming occurs are discussed.

Simple control-theoretic models of human steering activity in visually guided vehicle control

NASA Technical Reports Server (NTRS)

Hess, Ronald A.

1991-01-01

A simple control theoretic model of human steering or control activity in the lateral-directional control of vehicles such as automobiles and rotorcraft is discussed. The term 'control theoretic' is used to emphasize the fact that the model is derived from a consideration of well-known control system design principles as opposed to psychological theories regarding egomotion, etc. The model is employed to emphasize the 'closed-loop' nature of tasks involving the visually guided control of vehicles upon, or in close proximity to, the earth and to hypothesize how changes in vehicle dynamics can significantly alter the nature of the visual cues which a human might use in such tasks.

Quantitative force measurements using frequency modulation atomic force microscopy—theoretical foundations

NASA Astrophysics Data System (ADS)

Sader, John E.; Uchihashi, Takayuki; Higgins, Michael J.; Farrell, Alan; Nakayama, Yoshikazu; Jarvis, Suzanne P.

2005-03-01

Use of the atomic force microscope (AFM) in quantitative force measurements inherently requires a theoretical framework enabling conversion of the observed deflection properties of the cantilever to an interaction force. In this paper, the theoretical foundations of using frequency modulation atomic force microscopy (FM-AFM) in quantitative force measurements are examined and rigorously elucidated, with consideration being given to both 'conservative' and 'dissipative' interactions. This includes a detailed discussion of the underlying assumptions involved in such quantitative force measurements, the presentation of globally valid explicit formulae for evaluation of so-called 'conservative' and 'dissipative' forces, discussion of the origin of these forces, and analysis of the applicability of FM-AFM to quantitative force measurements in liquid.

Total Quality Management in a Knowledge Management Perspective.

ERIC Educational Resources Information Center

Johannsen, Carl Gustav

2000-01-01

Presents theoretical considerations on both similarities and differences between information management and knowledge management and presents a conceptual model of basic knowledge management processes. Discusses total quality management and quality control in the context of information management. (Author/LRW)

USSR and Eastern Europe Scientific Abstracts, Electronics and Electrical Engineering, No. 43.

DTIC Science & Technology

1978-11-16

WISOWSKI, JANUSZ; STOLARSKI, EDWARD and CZERWINSKI, ANDRZEJ , Institute of Electronic Technology NPCP [Scientific-Production Center for...PINTER (Mrs DUDAS ), MARTA [Abstract] Some theoretical considerations are presented concerning the design of small coaxial cables with

Objectives of the Airline Firm: Theory

NASA Technical Reports Server (NTRS)

Kneafsey, J. T.

1972-01-01

Theoretical models are formulated for airline firm operations that revolve around alternative formulations of managerial goals which these firms are persuing in practice. Consideration is given to the different objective functions which the companies are following in lieu of profit maximization.

Evaluation of test procedures for hydrogen environment embrittlement

NASA Technical Reports Server (NTRS)

Nelson, H. G.

1974-01-01

Report presents discussion of three common and primary influences on embrittlement process. Application of theoretical considerations to design of test coupons and methods is illustrated for both internal and external hydrogen embrittlement. Acceptable designs and methods are indicated.

Determining similarity in histological images using graph-theoretic description and matching methods for content-based image retrieval in medical diagnostics.

PubMed

Sharma, Harshita; Alekseychuk, Alexander; Leskovsky, Peter; Hellwich, Olaf; Anand, R S; Zerbe, Norman; Hufnagl, Peter

2012-10-04

Computer-based analysis of digitalized histological images has been gaining increasing attention, due to their extensive use in research and routine practice. The article aims to contribute towards the description and retrieval of histological images by employing a structural method using graphs. Due to their expressive ability, graphs are considered as a powerful and versatile representation formalism and have obtained a growing consideration especially by the image processing and computer vision community. The article describes a novel method for determining similarity between histological images through graph-theoretic description and matching, for the purpose of content-based retrieval. A higher order (region-based) graph-based representation of breast biopsy images has been attained and a tree-search based inexact graph matching technique has been employed that facilitates the automatic retrieval of images structurally similar to a given image from large databases. The results obtained and evaluation performed demonstrate the effectiveness and superiority of graph-based image retrieval over a common histogram-based technique. The employed graph matching complexity has been reduced compared to the state-of-the-art optimal inexact matching methods by applying a pre-requisite criterion for matching of nodes and a sophisticated design of the estimation function, especially the prognosis function. The proposed method is suitable for the retrieval of similar histological images, as suggested by the experimental and evaluation results obtained in the study. It is intended for the use in Content Based Image Retrieval (CBIR)-requiring applications in the areas of medical diagnostics and research, and can also be generalized for retrieval of different types of complex images. The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1224798882787923.

Determining similarity in histological images using graph-theoretic description and matching methods for content-based image retrieval in medical diagnostics

PubMed Central

2012-01-01

Background Computer-based analysis of digitalized histological images has been gaining increasing attention, due to their extensive use in research and routine practice. The article aims to contribute towards the description and retrieval of histological images by employing a structural method using graphs. Due to their expressive ability, graphs are considered as a powerful and versatile representation formalism and have obtained a growing consideration especially by the image processing and computer vision community. Methods The article describes a novel method for determining similarity between histological images through graph-theoretic description and matching, for the purpose of content-based retrieval. A higher order (region-based) graph-based representation of breast biopsy images has been attained and a tree-search based inexact graph matching technique has been employed that facilitates the automatic retrieval of images structurally similar to a given image from large databases. Results The results obtained and evaluation performed demonstrate the effectiveness and superiority of graph-based image retrieval over a common histogram-based technique. The employed graph matching complexity has been reduced compared to the state-of-the-art optimal inexact matching methods by applying a pre-requisite criterion for matching of nodes and a sophisticated design of the estimation function, especially the prognosis function. Conclusion The proposed method is suitable for the retrieval of similar histological images, as suggested by the experimental and evaluation results obtained in the study. It is intended for the use in Content Based Image Retrieval (CBIR)-requiring applications in the areas of medical diagnostics and research, and can also be generalized for retrieval of different types of complex images. Virtual Slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1224798882787923. PMID:23035717

A note on probabilistic models over strings: the linear algebra approach.

PubMed

Bouchard-Côté, Alexandre

2013-12-01

Probabilistic models over strings have played a key role in developing methods that take into consideration indels as phylogenetically informative events. There is an extensive literature on using automata and transducers on phylogenies to do inference on these probabilistic models, in which an important theoretical question is the complexity of computing the normalization of a class of string-valued graphical models. This question has been investigated using tools from combinatorics, dynamic programming, and graph theory, and has practical applications in Bayesian phylogenetics. In this work, we revisit this theoretical question from a different point of view, based on linear algebra. The main contribution is a set of results based on this linear algebra view that facilitate the analysis and design of inference algorithms on string-valued graphical models. As an illustration, we use this method to give a new elementary proof of a known result on the complexity of inference on the "TKF91" model, a well-known probabilistic model over strings. Compared to previous work, our proving method is easier to extend to other models, since it relies on a novel weak condition, triangular transducers, which is easy to establish in practice. The linear algebra view provides a concise way of describing transducer algorithms and their compositions, opens the possibility of transferring fast linear algebra libraries (for example, based on GPUs), as well as low rank matrix approximation methods, to string-valued inference problems.

Biomechanics of injury prediction for anthropomorphic manikins - preliminary design considerations

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

Engin, A.E.

1996-12-31

The anthropomorphic manikins are used in automobile safety research as well as in aerospace related applications. There is now a strong need to advance the biomechanics knowledge to determine appropriate criteria for injury likelihood prediction as functions of manikin-measured responses. In this paper, three regions of a manikin, namely, the head, knee joint, and lumbar spine are taken as examples to introduce preliminary design considerations for injury prediction by means of responses of theoretical models and strategically placed sensing devices.

Interleaved concatenated codes: new perspectives on approaching the Shannon limit.

PubMed

Viterbi, A J; Viterbi, A M; Sindhushayana, N T

1997-09-02

The last few years have witnessed a significant decrease in the gap between the Shannon channel capacity limit and what is practically achievable. Progress has resulted from novel extensions of previously known coding techniques involving interleaved concatenated codes. A considerable body of simulation results is now available, supported by an important but limited theoretical basis. This paper presents a computational technique which further ties simulation results to the known theory and reveals a considerable reduction in the complexity required to approach the Shannon limit.

Isolation and confinement - Considerations for colonization

NASA Technical Reports Server (NTRS)

Akins, F. R.

1978-01-01

This paper discusses three types of isolation (sensory/perceptual, temporal, and social) that could adversely affect mankind in space. The literature dealing with laboratory and field experiments relevant to these areas is summarized and suggestions are given for dealing with these problems within the space colony community. Also, consideration is given to the potential effects of physical confinement and the need for usable space. Finally, a modification of Maslow's hierarchy of needs is proposed as a theoretical framework to understand and investigate mankind's psychological needs in space.

Psychosocial Pain Management Moderation: The Limit, Activate, and Enhance Model.

PubMed

Day, Melissa A; Ehde, Dawn M; Jensen, Mark P

2015-10-01

There is a growing emphasis in the pain literature on understanding the following second-order research questions: Why do psychosocial pain treatments work? For whom do various treatments work? This critical review summarizes research that addresses the latter question and proposes a moderation model to help guide future research. A theoretical moderation framework for matching individuals to specific psychosocial pain interventions has been lacking. However, several such frameworks have been proposed in the broad psychotherapy and implementation science literature. Drawing on these theories and adapting them specifically for psychosocial pain treatment, here we propose a Limit, Activate, and Enhance model of pain treatment moderation. This model is unique in that it includes algorithms not only for matching treatments on the basis of patient weaknesses but also for directing patients to interventions that build on their strengths. Critically, this model provides a basis for specific a priori hypothesis generation, and a selection of the possible hypotheses drawn from the model are proposed and discussed. Future research considerations are presented that could refine and expand the model based on theoretically driven empirical evidence. The Limit, Activate, and Enhance model presented here is a theoretically derived framework that provides an a priori basis for hypothesis generation regarding psychosocial pain treatment moderators. The model will advance moderation research via its unique focus on matching patients to specific treatments that (1) limit maladaptive responses, (2) activate adaptive responses, and (3) enhance treatment outcomes based on patient strengths and resources. Copyright © 2015 American Pain Society. Published by Elsevier Inc. All rights reserved.

Structural characterization, spectroscopic signatures, nonlinear optical response, and antioxidant property of 4-benzyloxybenzaldehyde and its binding activity with microtubule-associated tau protein

NASA Astrophysics Data System (ADS)

Anbu, V.; Vijayalakshmi, K. A.; Karthick, T.; Tandon, Poonam; Narayana, B.

2017-09-01

In the proposed work, the non-linear optical response, spectroscopic signature and binding activity of 4-Benzyloxybenzaldehyde (4BB) has been investigated. In order to find the vibrational contribution of functional groups in mixed or coupled modes in the experimental FT-IR and FT-Raman spectra, the potential energy distribution (PED) based on the internal coordinates have been computed. Since the molecule exists in the form of dimer in solid state, the electronic structure of dimer has been proposed in order to explain the intermolecular hydrogen bonding interactions via aldehyde group. The experimental and simulated powder X-ray diffraction data was compared and the miller indices which define the crystallographic planes in the crystal lattices were identified. Optical transmittance and absorbance measurement were taken at ambient temperature in order to investigate the transparency and optical band gap. For screening the material for nonlinear applications, theoretical second order hyperpolarizability studies were performed and compared with the standard reference urea. To validate the theoretical results, powder second harmonic generation (SHG) studies were carried out using Kurtz and Perry technique. The results show that the molecule studied in this work exhibit considerable non-linear optical (NLO) response. In addition to the characterization and NLO studies, we also claimed based on the experimental and theoretical data that the molecule shows antioxidant property and inhibition capability. Since the title molecule shows significant binding with Tau protein that helps to stabilize microtubules in the nervous system, the molecular docking investigation was performed to find the inhibition constant, binding affinity and active binding residues.

A combined theoretical and in vitro modeling approach for predicting the magnetic capture and retention of magnetic nanoparticles in vivo

PubMed Central

David, Allan E.; Cole, Adam J.; Chertok, Beata; Park, Yoon Shin; Yang, Victor C.

2011-01-01

Magnetic nanoparticles (MNP) continue to draw considerable attention as potential diagnostic and therapeutic tools in the fight against cancer. Although many interacting forces present themselves during magnetic targeting of MNP to tumors, most theoretical considerations of this process ignore all except for the magnetic and drag forces. Our validation of a simple in vitro model against in vivo data, and subsequent reproduction of the in vitro results with a theoretical model indicated that these two forces do indeed dominate the magnetic capture of MNP. However, because nanoparticles can be subject to aggregation, and large MNP experience an increased magnetic force, the effects of surface forces on MNP stability cannot be ignored. We accounted for the aggregating surface forces simply by measuring the size of MNP retained from flow by magnetic fields, and utilized this size in the mathematical model. This presumably accounted for all particle-particle interactions, including those between magnetic dipoles. Thus, our “corrected” mathematical model provided a reasonable estimate of not only fractional MNP retention, but also predicted the regions of accumulation in a simulated capillary. Furthermore, the model was also utilized to calculate the effects of MNP size and spatial location, relative to the magnet, on targeting of MNPs to tumors. This combination of an in vitro model with a theoretical model could potentially assist with parametric evaluations of magnetic targeting, and enable rapid enhancement and optimization of magnetic targeting methodologies. PMID:21295085

Financing Opportunities for Renewable Energy Development in Alaska

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

Ardani, K.; Hillman, D.; Busche, S.

2013-04-01

This technical report provides an overview of existing and potential financing structures for renewable energy project development in Alaska with a focus on four primary sources of project funding: government financed or supported (the most commonly used structure in Alaska today), developer equity capital, commercial debt, and third-party tax-equity investment. While privately funded options currently have limited application in Alaska, their implementation is theoretically possible based on successful execution in similar circumstances elsewhere. This report concludes that while tax status is a key consideration in determining appropriate financing structure, there are opportunities for both taxable and tax-exempt entities to participatemore » in renewable energy project development.« less

Partial Variance of Increments Method in Solar Wind Observations and Plasma Simulations

NASA Astrophysics Data System (ADS)

Greco, A.; Matthaeus, W. H.; Perri, S.; Osman, K. T.; Servidio, S.; Wan, M.; Dmitruk, P.

2018-02-01

The method called "PVI" (Partial Variance of Increments) has been increasingly used in analysis of spacecraft and numerical simulation data since its inception in 2008. The purpose of the method is to study the kinematics and formation of coherent structures in space plasmas, a topic that has gained considerable attention, leading the development of identification methods, observations, and associated theoretical research based on numerical simulations. This review paper will summarize key features of the method and provide a synopsis of the main results obtained by various groups using the method. This will enable new users or those considering methods of this type to find details and background collected in one place.

Energy optimization aspects by injection process technology

NASA Astrophysics Data System (ADS)

Tulbure, A.; Ciortea, M.; Hutanu, C.; Farcas, V.

2016-08-01

In the proposed paper, the authors examine the energy aspects related to the injection moulding process technology in the automotive industry. Theoretical considerations have been validated by experimental measurements on the manufacturing process, for two types of injections moulding machines, hydraulic and electric. Practical measurements have been taken with professional equipment separately on each technological operation: lamination, compression, injection and expansion. For results traceability, the following parameters were, whenever possible, maintained: cycle time, product weight and the relative time. The aim of the investigations was to carry out a professional energy audit with accurate losses identification. Base on technological diagram for each production cycle, at the end of this contribution, some measure to reduce the energy consumption were proposed.

Layered Composite Analysis Capability

NASA Technical Reports Server (NTRS)

Narayanaswami, R.; Cole, J. G.

1985-01-01

Laminated composite material construction is gaining popularity within industry as an attractive alternative to metallic designs where high strength at reduced weights is of prime consideration. This has necessitated the development of an effective analysis capability for the static, dynamic and buckling analyses of structural components constructed of layered composites. Theoretical and user aspects of layered composite analysis and its incorporation into CSA/NASTRAN are discussed. The availability of stress and strain based failure criteria is described which aids the user in reviewing the voluminous output normally produced in such analyses. Simple strategies to obtain minimum weight designs of composite structures are discussed. Several example problems are presented to demonstrate the accuracy and user convenient features of the capability.

The role of astrocytic glycogen in supporting the energetics of neuronal activity.

PubMed

Dinuzzo, Mauro; Mangia, Silvia; Maraviglia, Bruno; Giove, Federico

2012-11-01

Energy homeostasis in the brain is maintained by oxidative metabolism of glucose, primarily to fulfil the energy demand associated with ionic movements in neurons and astrocytes. In this contribution we review the experimental evidence that grounds a specific role of glycogen metabolism in supporting the functional energetic needs of astrocytes during the removal of extracellular potassium. Based on theoretical considerations, we further discuss the hypothesis that the mobilization of glycogen in astrocytes serves the purpose to enhance the availability of glucose for neuronal glycolytic and oxidative metabolism at the onset of stimulation. Finally, we provide an evolutionary perspective for explaining the selection of glycogen as carbohydrate reserve in the energy-sensing machinery of cell metabolism.

Optical absorption in planar graphene superlattice: The role of structural parameters

NASA Astrophysics Data System (ADS)

Azadi, L.; Shojaei, S.

2018-04-01

We theoretically studied the optically driven interband transitions in a planar graphene superlattices (PGSL) formed by patterning graphene sheet on laterally hetrostructured substrate as Sio2/hBN. A tunable optical transitions between minibands is observed based on engineering structural parameters. We derive analytically expression for optical absorption from two-band model. Considerable optical absorption is obtained for different ratios between widths of heterostructured substrate and is explained analytically from the view point of wavefunction engineering and miniband dispersion, in details. The role of different statuses of polarization as circular and linear are considered. Our study paves a way toward the control of optical properties of PGSLs to be implemented in optoelectronics devices.

Sensorless speed detection of squirrel-cage induction machines using stator neutral point voltage harmonics

NASA Astrophysics Data System (ADS)

Petrovic, Goran; Kilic, Tomislav; Terzic, Bozo

2009-04-01

In this paper a sensorless speed detection method of induction squirrel-cage machines is presented. This method is based on frequency determination of the stator neutral point voltage primary slot harmonic, which is dependent on rotor speed. In order to prove method in steady state and dynamic conditions the simulation and experimental study was carried out. For theoretical investigation the mathematical model of squirrel cage induction machines, which takes into consideration actual geometry and windings layout, is used. Speed-related harmonics that arise from rotor slotting are analyzed using digital signal processing and DFT algorithm with Hanning window. The performance of the method is demonstrated over a wide range of load conditions.

Origin of the moon - The collision hypothesis

NASA Technical Reports Server (NTRS)

Stevenson, D. J.

1987-01-01

Theoretical models of lunar origin involving one or more collisions between the earth and other large sun-orbiting bodies are examined in a critical review. Ten basic propositions of the collision hypothesis (CH) are listed; observational data on mass and angular momentum, bulk chemistry, volatile depletion, trace elements, primordial high temperatures, and orbital evolution are summarized; and the basic tenets of alternative models (fission, capture, and coformation) are reviewed. Consideration is given to the thermodynamics of large impacts, rheological and dynamical problems, numerical simulations based on the CH, disk evolution models, and the chemical implications of the CH. It is concluded that the sound arguments and evidence supporting the CH are not (yet) sufficient to rule out other hypotheses.

Accuracy of a class of concurrent algorithms for transient finite element analysis

NASA Technical Reports Server (NTRS)

Ortiz, Michael; Sotelino, Elisa D.; Nour-Omid, Bahram

1988-01-01

The accuracy of a new class of concurrent procedures for transient finite element analysis is examined. A phase error analysis is carried out which shows that wave retardation leading to unacceptable loss of accuracy may occur if a Courant condition based on the dimensions of the subdomains is violated. Numerical tests suggest that this Courant condition is conservative for typical structural applications and may lead to a marked increase in accuracy as the number of subdomains is increased. Theoretical speed-up ratios are derived which suggest that the algorithms under consideration can be expected to exhibit a performance superior to that of globally implicit methods when implemented on parallel machines.

Modeling of vortex generated sound in solid propellant rocket motors

NASA Technical Reports Server (NTRS)

Flandro, G. A.

1980-01-01

There is considerable evidence based on both full scale firings and cold flow simulations that hydrodynamically unstable shear flows in solid propellant rocket motors can lead to acoustic pressure fluctuations of significant amplitude. Although a comprehensive theoretical understanding of this problem does not yet exist, procedures were explored for generating useful analytical models describing the vortex shedding phenomenon and the mechanisms of coupling to the acoustic field in a rocket combustion chamber. Since combustion stability prediction procedures cannot be successful without incorporation of all acoustic gains and losses, it is clear that a vortex driving model comparable in quality to the analytical models currently employed to represent linear combustion instability must be formulated.

Dynamic regulation of erythropoiesis: A computer model of general applicability

NASA Technical Reports Server (NTRS)

Leonard, J. I.

1979-01-01

A mathematical model for the control of erythropoiesis was developed based on the balance between oxygen supply and demand at a renal oxygen detector which controls erythropoietin release and red cell production. Feedback regulation of tissue oxygen tension is accomplished by adjustments of hemoglobin levels resulting from the output of a renal-bone marrow controller. Special consideration was given to the determinants of tissue oxygenation including evaluation of the influence of blood flow, capillary diffusivity, oxygen uptake and oxygen-hemoglobin affinity. A theoretical analysis of the overall control system is presented. Computer simulations of altitude hypoxia, red cell infusion hyperoxia, and homolytic anemia demonstrate validity of the model for general human application in health and disease.

Gravity discharge vessel revisited: An explicit Lambert W function solution

NASA Astrophysics Data System (ADS)

Digilov, Rafael M.

2017-07-01

Based on the generalized Poiseuille equation modified by a kinetic energy correction, an explicit solution for the time evolution of a liquid column draining under gravity through an exit capillary tube is derived in terms of the Lambert W function. In contrast to the conventional exponential behavior, as implied by the Poiseuille law, a new analytical solution gives a full account for the volumetric flow rate of a fluid through a capillary of any length and improves the precision of viscosity determination. The theoretical consideration may be of interest to students as an example of how implicit equations in the field of physics can be solved analytically using the Lambert function.

Advanced turboprop noise prediction: Development of a code at NASA Langley based on recent theoretical results

NASA Technical Reports Server (NTRS)

Farassat, F.; Dunn, M. H.; Padula, S. L.

1986-01-01

The development of a high speed propeller noise prediction code at Langley Research Center is described. The code utilizes two recent acoustic formulations in the time domain for subsonic and supersonic sources. The structure and capabilities of the code are discussed. Grid size study for accuracy and speed of execution on a computer is also presented. The code is tested against an earlier Langley code. Considerable increase in accuracy and speed of execution are observed. Some examples of noise prediction of a high speed propeller for which acoustic test data are available are given. A brisk derivation of formulations used is given in an appendix.

Fractography of cast gypsum.

PubMed

Mori, T; Yamane, M

1982-02-01

A fractographical study of dental cast gypsum was made in order to correlate the mechanical properties with the microstructure. Wet specimens fractured under tensile stress showed intercrystalline fracture and the tensile strength depended on the porosity present. Thus, it was assumed that tensile strength was dependent on the contact area between individual gypsum crystals and changes in porosity approximated to changes in contact area. Strength differences among specimens of a given W/P ratio, therefore, can be related to differences in intercrystalline contact areas. These theoretical considerations suggest that the classification of dental die stone and dental stone into high and low strength types based on strength properties only would be more practical and less confusing than at present.

Is inequality harmful for the environment? An empirical analysis applied to developing and transition countries.

PubMed

Clement, Matthieu; Meunie, Andre

2010-01-01

The object of this article is to examine the relation between social inequalities and pollution. First of all we provide a survey demonstrating that, from a theoretical point of view, a decrease in inequality has an uncertain impact on the environment. Second, on the basis of these conceptual considerations, we propose an econometric analysis based on panel data (fixed-effects and dynamic panel data models) concerning developing and transition countries for the 1988-2003 period. We examine specifically the effect of inequality on the extent of local pollution (sulphur dioxide emissions and organic water pollution) by integrating the Gini index into the formulation of the environmental Kuznets' curve.

Coal mining, social injustice and health: a universal conflict of power and priorities.

PubMed

Morrice, Emily; Colagiuri, Ruth

2013-01-01

Given the current insatiable demand for coal to build and fuel the world's burgeoning cities the debate about mining-related social, environmental and health injustices remains eminently salient. Furthermore, the core issues appear universally consistent. This paper combines the theoretical base for defining these injustices with reports in the international health literature about the impact of coal mining on local communities. It explores and analyses mechanisms of coal mining related injustice, conflicting priorities and power asymmetries between political and industry interests versus inhabitants of mining communities, and asks what would be required for considerations of health to take precedence over wealth. Copyright © 2012 Elsevier Ltd. All rights reserved.

The detection of climate change due to the enhanced greenhouse effect

NASA Technical Reports Server (NTRS)

Schiffer, Robert A.; Unninayar, Sushel

1991-01-01

The greenhouse effect is accepted as an undisputed fact from both theoretical and observational considerations. In Earth's atmosphere, the primary greenhouse gas is water vapor. The specific concern today is that increasing concentrations of anthropogenically introduced greenhouse gases will, sooner or later, irreversibly alter the climate of Earth. Detecting climate change has been complicated by uncertainties in historical observations and measurements. Thus, the primary concern for the GEDEX project is how can climate change and enhanced greenhouse effects be unambiguously detected and quantified. Specifically examined are the areas of: Earth surface temperature; the free atmosphere (850 millibars and above); space-based measurements; measurement uncertainties; and modeling the observed temperature record.

Ferromagnetic resonance study of the non-stoichiometric double perovskite Sr2Fe1+xMo1-xO6

NASA Astrophysics Data System (ADS)

Medina, J. De La Torre; Piraux, L.; Soto, T. E.; Morales, R.; Navarro, O.

2018-02-01

In this work we report a ferromagnetic resonance study on the magnetic properties of double perovskite compounds fab-ricated by solid state reaction. Based on a mean field approach, along with morphological considerations, we accurately determined the saturation magnetization of the non-stoichiometric double perovskite Sr2Fe1+xMo1-xO6. Our approach has revealed a direct in-fluence of composition on the overall magnetic behavior of these materials, providing complementary experimental evidence that corroborates previous theoretical findings. The understanding of the influence of composition is of paramount importance for the design of ferromagnetic oxides with tunable magnetic and magneto-transport behavior.

Theoretical and practical considerations for the development of online international collaborative learning for dental hygiene students.

PubMed

Gussy, M G; Knevel, R J M; Sigurdson, V; Karlberg, G

2006-08-01

Globalization and concurrent development in computer and communication technology has increased interest in collaborative online teaching and learning for students in higher education institutions. Many institutions and teachers have introduced computer-supported programmes in areas including dental hygiene. The potential for the use of this technology is exciting; however, its introduction should be careful and considered. We suggest that educators wanting to introduce computer-supported programmes make explicit their pedagogical principles and then select technologies that support and exploit these principles. This paper describes this process as it was applied to the development of an international web-based collaborative learning programme for dental hygiene students.

Studies of Particle Acceleration, Transport and Radiation in Impulsive Phase of Solar Flares

NASA Technical Reports Server (NTRS)

Petrosian, Vahe

2005-01-01

Solar activity and its most prominent aspect, the solar flares, have considerable influence on terrestrial and space weather. Solar flares also provide a suitable laboratory for the investigation of many plasma and high energy processes important in the magnetosphere of the Earth and many other space and astrophysical situations. Hence, progress in understanding of flares will have considerable scientific and societal impact. The primary goal of this grant is the understanding of two of the most important problems of solar flare physics, namely the determination of the energy release mechanism and how this energy accelerates particles. This is done through comparison of the observations with theoretical models, starting from observations and gradually proceeding to theoretically more complex situations as the lower foundations of our understanding are secured. It is generally agreed that the source of the flare energy is the annihilation of magnetic fields by the reconnection process. Exactly how this energy is released or how it is dissipated remains controversial. Moreover, the exact mechanism of the acceleration of the particles is still a matter of debate. Data from many spacecrafts and ground based instruments obtained over the past decades have given us some clues. Theoretical analyses of these data have led to the standard thick target model (STT) where most of the released energy goes into an (assumed) power law spectrum of accelerated particles, and where all the observed radiations are the consequence of the interaction of these particles with the flare plasma. However, some theoretical arguments, and more importantly some new observations, have led us to believe that the above picture is not complete. It appears that plasma turbulence plays a more prominent role than suspected previously, and that it is the most likely agent for accelerating particles. The model we have developed is based on production of a high level of plasma waves and turbulence in the reconnection region above a flare loop. This turbulence accelerates particles stochastically which radiate some of their energy in this region but carry most of their energy to the footpoints of the loop, where they lose all their energy and radiate bulk of the observed radiation as in the traditional thick target model. In the past we have worked on various aspects of this model. We have evaluated the interaction rates of the plasma waves with electrons and ions, developed theoretical frameworks for the acceleration, transport and radiative processes, and produced numerical codes for the investigation of these processes. The goal of this grant has been further development and testing of this new paradigm, with emphases on the relative acceleration of electrons and ions and on a comprehensive investigation of the turbulence generation, cascade, and damping processes. We review several pieces of important evidence that we have uncovered indicating the crucial roles of turbulence, in and we describe accomplishments during the past two years of this grant.

Enhancing rigor and practice of scoping reviews in social policy research: considerations from a worked example on the Americans with disabilities act.

PubMed

Harris, Sarah Parker; Gould, Robert; Fujiura, Glenn

2015-01-01

There is increasing theoretical consideration about the use of systematic and scoping reviews of evidence in informing disability and rehabilitation research and practice. Indicative of this trend, this journal published a piece by Rumrill, Fitzgerald and Merchant in 2010 explaining the utility and process for conducting reviews of intervention-based research. There is still need to consider how to apply such rigor when conducting more exploratory reviews of heterogeneous research. This article explores the challenges, benefits, and procedures for conducting rigorous exploratory scoping reviews of diverse evidence. The article expands upon Rumrill, Fitzgerald and Merchant's framework and considers its application to more heterogeneous evidence on the impact of social policy. A worked example of a scoping review of the Americans with Disabilities Act is provided with a procedural framework for conducting scoping reviews on the effects of a social policy. The need for more nuanced techniques for enhancing rigor became apparent during the review process. There are multiple methodological steps that can enhance the utility of exploratory scoping reviews. The potential of systematic consideration during the exploratory review process is shown as a viable method to enhance the rigor in reviewing diverse bodies of evidence.

Behavior of Tachyon in String Cosmology Based on Gauged WZW Model

NASA Astrophysics Data System (ADS)

Lee, Sunggeun; Nam, Soonkeon

We investigate a string theoretic cosmological model in the context of the gauged Wess-Zumino-Witten model. Our model is based on a product of non-compact coset space and a spectator flat space; [SL(2, R)/U(1)]k × ℝ2. We extend the formerly studied semiclassical consideration with infinite Kac-Moody level k to a finite one. In this case, the tachyon field appears in the effective action, and we solve the Einstein equation to determine the behavior of tachyon as a function of time. We find that tachyon field dominates over dilaton field in early times. In particular, we consider the energy conditions of the matter fields consisting of the dilaton and the tachyon which affect the initial singularity. We find that not only the strong energy but also the null energy condition is violated.

Anomalous interface adhesion of graphene membranes

PubMed Central

He, Y.; Chen, W. F.; Yu, W. B.; Ouyang, G.; Yang, G. W.

2013-01-01

In order to understand the anomalous interface adhesion properties between graphene membranes and their substrates, we have developed a theoretical method to calibrate the interface adhesion energy of monolayer and multilayer graphene on substrates based on the bond relaxation consideration. Four kinds of interfaces, including graphene/SiO2, graphene/Cu, graphene/Cu/Ni and Cu/graphene/Ni, were taken into account. It was found that the membrane thickness and the interface confinement condition determine the adhesion energy. The relationship between the critical interface separation and the graphene thickness showed that the interface separation in the self-equilibrium state drops with decreasing membrane thickness. The size-dependent Young's modulus of graphene membrane and the interfacial condition were responsible for the novel interface adhesion energy. The proposed theory was expected to be applied to the design of graphene-based devices. PMID:24036502

The role of external and internal mass transfer in the process of Cu2+ removal by natural mineral sorbents.

PubMed

Sljivić, M; Smiciklas, I; Plećas, I; Pejanović, S

2011-07-01

The kinetics of Cu2+ sorption on to zeolite, clay and diatomite was investigated as a function of initial metal concentrations. For consideration of the mass transfer phenomena, single resistance models based on both film and intraparticle diffusion were tested and compared. The obtained results suggested that the rate-limiting step in Cu2+ sorption strongly depended on the sorbent type, as well as on initial cation concentration. The decrease in external mass transfer coefficients with the increase in initial metal concentrations was in excellent agreement with expressions based on Sherwood and Schmidt dimensionless numbers. The internal diffusivities through zeolite particles were in the range 1.0 x 10(-11) to 1.0 x 10(-13) m2/min, depending on the Cu2+ concentration and the applied theoretical model.

Dissecting Practical Intelligence Theory: Its Claims and Evidence.

ERIC Educational Resources Information Center

Gottfredson, Linda S.

2003-01-01

The two key theoretical propositions of "Practical Intelligence in Everyday Life" are made plausible only if one ignores considerable evidence contradicting them. The six key empirical claims rest primarily on the illusion of evidence enhanced by selective reporting of results. (SLD)

Integrative Family Therapy: Theoretical Considerations.

ERIC Educational Resources Information Center

Walsh, William M.

Integrative family therapy is an integration of personality theory and counseling theory actualized in the counseling process. Personality theory contributes five interrelated concepts to a model of family therapy, including communication/perception, individual roles, family subunits, family themes, and individual personality dynamics; these…

A non-extensive thermodynamic theory of ecological systems

NASA Astrophysics Data System (ADS)

Van Xuan, Le; Khac Ngoc, Nguyen; Lan, Nguyen Tri; Viet, Nguyen Ai

2017-06-01

After almost 30 years of development, it is not controversial issue that the so-called Tsallis entropy provides a useful approach to studying the complexity where the non-additivity of the systems under consideration is frequently met. Also, in the ecological research, Tsallis entropy, or in other words, q-entropy has been found itself as a generalized approach to define a range of diversity indices including Shannon-Wiener and Simpson indices. As a further stage of development in theoretical research, a thermodynamic theory based on Tsallis entropy or diversity indices in ecology has to be constructed for ecological systems to provide knowledge of ecological macroscopic behaviors. The standard method of theoretical physics is used in the manipulation and the equivalence between phenomenological thermodynamics and ecological aspects is the purpose of the ongoing research. The present work is in the line of the authors research to implement Tsallis non-extensivity approach to obtain the most important thermodynamic quantities of ecological systems such as internal energy Uq and temperature Tq based on a given modeled truncated Boltzmann distribution of the Whittaker plot for a dataset. These quantities have their own ecological meaning, especially the temperature Tq provides the insight of equilibrium condition among ecological systems as it is well-known in 0th law of thermodynamics.

A review and assessment of hydrodynamic cavitation as a technology for the future.

PubMed

Gogate, Parag R; Pandit, Aniruddha B

2005-01-01

In the present work, the current status of the hydrodynamic cavitation reactors has been reviewed discussing the bubble dynamics analysis, optimum design considerations, design correlations for cavitational intensity (in terms of collapse pressure)/cavitational yield and different successful chemical synthesis applications clearly illustrating the utility of these types of reactors. The theoretical discussion based on the modeling of the bubble dynamics equations aims at understanding the design information related to the dependency of the cavitational intensity on the operating parameters and recommendations have been made for the choice of the optimized conditions of operating parameters. The design information based on the theoretical analysis has also been supported with some experimental illustrations concentrating on the chemical synthesis applications. Assessment of the hydrodynamic cavitation reactors and comparison with the sonochemical reactors has been done by citing the different industrially important reactions (oxidation of toluene, o-xylene, m-xylene, p-xylene, mesitylene, o-nitrotoluene, p-nitrotoluene, m-nitrotoluene, o-chlorotoluene and p-chlorotoulene, and trans-esterification reaction i.e., synthesis of bio-diesel). Some recommendations have also been made for the future work to be carried out as well as the choice of the operating conditions for realizing the dream of industrial scale applications of the cavitational reactors.

Analysis of entropy extraction efficiencies in random number generation systems

NASA Astrophysics Data System (ADS)

Wang, Chao; Wang, Shuang; Chen, Wei; Yin, Zhen-Qiang; Han, Zheng-Fu

2016-05-01

Random numbers (RNs) have applications in many areas: lottery games, gambling, computer simulation, and, most importantly, cryptography [N. Gisin et al., Rev. Mod. Phys. 74 (2002) 145]. In cryptography theory, the theoretical security of the system calls for high quality RNs. Therefore, developing methods for producing unpredictable RNs with adequate speed is an attractive topic. Early on, despite the lack of theoretical support, pseudo RNs generated by algorithmic methods performed well and satisfied reasonable statistical requirements. However, as implemented, those pseudorandom sequences were completely determined by mathematical formulas and initial seeds, which cannot introduce extra entropy or information. In these cases, “random” bits are generated that are not at all random. Physical random number generators (RNGs), which, in contrast to algorithmic methods, are based on unpredictable physical random phenomena, have attracted considerable research interest. However, the way that we extract random bits from those physical entropy sources has a large influence on the efficiency and performance of the system. In this manuscript, we will review and discuss several randomness extraction schemes that are based on radiation or photon arrival times. We analyze the robustness, post-processing requirements and, in particular, the extraction efficiency of those methods to aid in the construction of efficient, compact and robust physical RNG systems.

Sensing network for electromagnetic fields generated by seismic activities

NASA Astrophysics Data System (ADS)

Gershenzon, Naum I.; Bambakidis, Gust; Ternovskiy, Igor V.

2014-06-01

The sensors network is becoming prolific and play now increasingly more important role in acquiring and processing information. Cyber-Physical Systems are focusing on investigation of integrated systems that includes sensing, networking, and computations. The physics of the seismic measurement and electromagnetic field measurement requires special consideration how to design electromagnetic field measurement networks for both research and detection earthquakes and explosions along with the seismic measurement networks. In addition, the electromagnetic sensor network itself could be designed and deployed, as a research tool with great deal of flexibility, the placement of the measuring nodes must be design based on systematic analysis of the seismic-electromagnetic interaction. In this article, we review the observations of the co-seismic electromagnetic field generated by earthquakes and man-made sources such as vibrations and explosions. The theoretical investigation allows the distribution of sensor nodes to be optimized and could be used to support existing geological networks. The placement of sensor nodes have to be determined based on physics of electromagnetic field distribution above the ground level. The results of theoretical investigations of seismo-electromagnetic phenomena are considered in Section I. First, we compare the relative contribution of various types of mechano-electromagnetic mechanisms and then analyze in detail the calculation of electromagnetic fields generated by piezomagnetic and electrokinetic effects.

On the Road to Translation for PTSD Treatment: Theoretical and Practical Considerations of the Use of Human Models of Conditioned Fear for Drug Development.

PubMed

Risbrough, Victoria B; Glenn, Daniel E; Baker, Dewleen G

The use of quantitative, laboratory-based measures of threat in humans for proof-of-concept studies and target development for novel drug discovery has grown tremendously in the last 2 decades. In particular, in the field of posttraumatic stress disorder (PTSD), human models of fear conditioning have been critical in shaping our theoretical understanding of fear processes and importantly, validating findings from animal models of the neural substrates and signaling pathways required for these complex processes. Here, we will review the use of laboratory-based measures of fear processes in humans including cued and contextual conditioning, generalization, extinction, reconsolidation, and reinstatement to develop novel drug treatments for PTSD. We will primarily focus on recent advances in using behavioral and physiological measures of fear, discussing their sensitivity as biobehavioral markers of PTSD symptoms, their response to known and novel PTSD treatments, and in the case of d-cycloserine, how well these findings have translated to outcomes in clinical trials. We will highlight some gaps in the literature and needs for future research, discuss benefits and limitations of these outcome measures in designing proof-of-concept trials, and offer practical guidelines on design and interpretation when using these fear models for drug discovery.

Alternative approaches to analytical designs in occupational injury epidemiology.

PubMed

Mittleman, M A; Maldonado, G; Gerberich, S G; Smith, G S; Sorock, G S

1997-08-01

In this paper, we discuss the theoretical framework upon which observational studies of occupational injuries are based. Following a general description of how causal effects are estimated, the challenges faced by researchers working in this area are outlined, with an emphasis on case-control studies. These challenges include defining the at-risk period for workers whose tasks change over time and whose hazard period may be very brief, evaluating the underreporting of both exposures and injuries, and considering the effects of multiple injuries per individual on study design and data analysis. We review both the theoretical and practical considerations in the design and conduct of traditional case-control studies, based on the collection of individual level data, as well as other approaches, such as using information culled from administrative and descriptive databases, and case-control studies in which the plant or work site is the unit of analysis. The case-crossover design is also reviewed and its utility for reducing confounding due to differences between individuals by self-matching is highlighted. While this design has not yet been applied to the work setting, its potential for increasing our understanding of the causes of acute-onset occupational injuries seems promising. Finally, a variety of hybrid designs are discussed, including combinations of case-control, case-crossover, and cohort designs.

A close examination of double filtering with fold change and t test in microarray analysis

PubMed Central

2009-01-01

Background Many researchers use the double filtering procedure with fold change and t test to identify differentially expressed genes, in the hope that the double filtering will provide extra confidence in the results. Due to its simplicity, the double filtering procedure has been popular with applied researchers despite the development of more sophisticated methods. Results This paper, for the first time to our knowledge, provides theoretical insight on the drawback of the double filtering procedure. We show that fold change assumes all genes to have a common variance while t statistic assumes gene-specific variances. The two statistics are based on contradicting assumptions. Under the assumption that gene variances arise from a mixture of a common variance and gene-specific variances, we develop the theoretically most powerful likelihood ratio test statistic. We further demonstrate that the posterior inference based on a Bayesian mixture model and the widely used significance analysis of microarrays (SAM) statistic are better approximations to the likelihood ratio test than the double filtering procedure. Conclusion We demonstrate through hypothesis testing theory, simulation studies and real data examples, that well constructed shrinkage testing methods, which can be united under the mixture gene variance assumption, can considerably outperform the double filtering procedure. PMID:19995439

Mesh-type acoustic vector sensor

NASA Astrophysics Data System (ADS)

Zalalutdinov, M. K.; Photiadis, D. M.; Szymczak, W. G.; McMahon, J. W.; Bucaro, J. A.; Houston, B. H.

2017-07-01

Motivated by the predictions of a theoretical model developed to describe the acoustic flow force exerted on closely spaced nano-fibers in a viscous medium, we have demonstrated a novel concept for a particle velocity-based directional acoustic sensor. The central element of the concept exploits the acoustically induced normal displacement of a fine mesh as a measure of the collinear projection of the particle velocity in the sound wave. The key observations are (i) the acoustically induced flow force on an individual fiber within the mesh is nearly independent of the fiber diameter and (ii) the mesh-flow interaction can be well-described theoretically by a nearest neighbor coupling approximation. Scaling arguments based on these two observations indicate that the refinement of the mesh down to the nanoscale leads to significant improvements in performance. The combination of the two dimensional nature of the mesh together with the nanoscale dimensions provides a dramatic gain in the total length of fiber exposed to the flow, leading to a sensitivity enhancement by orders of magnitude. We describe the fabrication of a prototype mesh sensor equipped with optical readout. Preliminary measurements carried out over a considerable bandwidth together with the results of numerical simulations are in good agreement with the theory, thus providing a proof of concept.

Making sense of shared sense-making in an inquiry-based science classroom: Toward a sociocultural theory of mind

NASA Astrophysics Data System (ADS)

Ladewski, Barbara G.

Despite considerable exploration of inquiry and reflection in the literatures of science education and teacher education/teacher professional development over the past century, few theoretical or analytical tools exist to characterize these processes within a naturalistic classroom context. In addition, little is known regarding possible developmental trajectories for inquiry or reflection---for teachers or students---as these processes develop within a classroom context over time. In the dissertation, I use a sociocultural lens to explore these issues with an eye to the ways in which teachers and students develop shared sense-making, rather than from the more traditional perspective of individual teacher activity or student learning. The study includes both theoretical and empirical components. Theoretically, I explore the elaborations of sociocultural theory needed to characterize teacher-student shared sense-making as it develops within a classroom context, and, in particular, the role of inquiry and reflection in that sense-making. I develop a sociocultural model of shared sense-making that attempts to represent the dialectic between the individual and the social, through an elaboration of existing sociocultural and psychological constructs, including Vygotsky's zone of proximal development and theory of mind. Using this model as an interpretive framework, I develop a case study that explores teacher-student shared sense-making within a middle-school science classroom across a year of scaffolded introduction to inquiry-based science instruction. The empirical study serves not only as a test case for the theoretical model, but also informs our understanding regarding possible developmental trajectories and important mechanisms supporting and constraining shared sense-making within inquiry-based science classrooms. Theoretical and empirical findings provide support for the idea that perspectival shifts---that is, shifts of point-of-view that alter relationships and proximities of elements within the interaction space---play an important role in shared sense-making. Findings further suggest that the mutually constitutive interaction of inquiry and reflection plays a key role in flexible shared sense-making. Finally, findings lend support to the idea of a dialectical relationship between human models of shared sense-making and human systems of shared sense-making; that is, the ways in which human minds are coordinated is a work in progress, shaping and shaped by human culture.

Wavelength-Adaptive Dehazing Using Histogram Merging-Based Classification for UAV Images

PubMed Central

Yoon, Inhye; Jeong, Seokhwa; Jeong, Jaeheon; Seo, Doochun; Paik, Joonki

2015-01-01

Since incoming light to an unmanned aerial vehicle (UAV) platform can be scattered by haze and dust in the atmosphere, the acquired image loses the original color and brightness of the subject. Enhancement of hazy images is an important task in improving the visibility of various UAV images. This paper presents a spatially-adaptive dehazing algorithm that merges color histograms with consideration of the wavelength-dependent atmospheric turbidity. Based on the wavelength-adaptive hazy image acquisition model, the proposed dehazing algorithm consists of three steps: (i) image segmentation based on geometric classes; (ii) generation of the context-adaptive transmission map; and (iii) intensity transformation for enhancing a hazy UAV image. The major contribution of the research is a novel hazy UAV image degradation model by considering the wavelength of light sources. In addition, the proposed transmission map provides a theoretical basis to differentiate visually important regions from others based on the turbidity and merged classification results. PMID:25808767

Fast neutron sensitivity of neutron detectors based on Boron-10 converter layers

NASA Astrophysics Data System (ADS)

Mauri, G.; Messi, F.; Kanaki, K.; Hall-Wilton, R.; Karnickis, E.; Khaplanov, A.; Piscitelli, F.

2018-03-01

In the last few years many detector technologies for thermal neutron detection have been developed in order to face the shortage of 3He, which is now much less available and more expensive. Moreover the 3He-based detectors can not fulfil the requirements in performance, e.g. the spatial resolution and the counting rate capability needed for the new instruments. The Boron-10-based gaseous detectors have been proposed as a suitable choice. This and other alternative technologies are being developed at ESS. Higher intensities mean higher signals but higher background as well. The signal-to-background ratio is an important feature to study, in particular the γ-ray and the fast neutron contributions. This paper investigates, for the first time, the fast neutrons sensitivity of 10B-based thermal neutron detector. It presents the study of the detector response as a function of energy threshold and the underlying physical mechanisms. The latter are explained with the help of theoretical considerations and simulations.

Calibration and evaluation of a real-time cascade impactor

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

Fairchild, C.I.; Wheat, L.D.

1984-04-01

A 10-stage cascade impactor made by California Measurement Inc., can determine aerodynamic size distributions of dilute aerosols in a few minutes. Collection of impacted particles on greased, vibrating piezoelectric crystals produces changes in vibrational frequency proportional to the collected mass. Based on frequency changes and sampling time, a data reduction module calculates the mass collected on each stage. Calibration of the assembled impactor was performed with monodisperse polystyrene latex (PSL) and Eosin-Y (E-Y) aerosols for the lower stages (4-10), and PSL and pollen particles (ragweed and mulberry) for the upper stages (1-3). The stage experimental effective cutoff aerodynamic diameters (ECAD)more » were up to 22 percent different from theoretical ECADs with the exception of Stages 1 and 2 which were respectively 30 and 35 percent different from theoretical ECADs. The overall loss of particles > 3- and < 0.3-..mu..m was severe. Also, considerable scatter of particles was observed on the collection crystals of Stages 1 and 2. Although a majority of particles were in the impaction area, a large fraction was scattered over the outer portions of these crystals.« less

Effect of pressure on Zircon's (ZrSiO4) Raman active modes: a first-principles study

NASA Astrophysics Data System (ADS)

Sheremetyeva, Natalya; Cherniak, Daniele; Watson, Bruce; Meunier, Vincent

Zircon is a mineral commonly found in the Earth crust. Its remarkable properties have given rise to considerable attention. This includes possible inclusion of radioactive elements in natural samples, which allows for geochronological investigations. Subsequently, Zircon was proposed as possible host material for radioactive waste management. Internal radiation damage in zircon leads to the destruction of its crystal structure (an effect known as metamictization) which is subject to ongoing research. Recently, the effect of pressure and temperature on synthetic zircon has been analyzed experimentally using Raman spectroscopy which led to the calibration of zircon as a pressure sensor in diamond-anvil cell experiments. While there have been a number of theoretical studies, the effect of pressure on the Raman active modes of zircon has not been investigated theoretically. Here we present a first-principles pressure calibration of the Raman active modes in Zircon employing density-functional theory (DFT). We find excellent quantitative agreement of the slopes ∂ω / ∂P with the experimental ones and are able to rationalize the ω vs. P behavior based on the details of the vibrational modes.

Cognitive representations of breast cancer, emotional distress and preventive health behaviour: a theoretical perspective.

PubMed

Decruyenaere, M; Evers-Kiebooms, G; Welkenhuysen, M; Denayer, L; Claes, E

2000-01-01

Individuals at high risk for developing breast and/or ovarian cancer are faced with difficult decisions regarding genetic testing, cancer prevention and/or intensive surveillance. Large interindividual differences exist in the uptake of these health-related services. This paper is aimed at understanding and predicting how people emotionally and behaviourally react to information concerning genetic predisposition to breast/ovarian cancer. For this purpose, the self-regulation model of illness representations is elaborated. This model suggests that health-related behaviour is influenced by a person's cognitive and emotional representation of the health threat. These representations generate coping behaviour aimed at resolving the objective health problems (problem-focussed coping) and at reducing the emotional distress induced by the health threat (emotion-focussed coping). Based on theoretical considerations and empirical studies, four interrelated attributes of the cognitive illness representation of hereditary breast/ovarian cancer are described: causal beliefs concerning the disease, perceived severity, perceived susceptibility to the disease and perceived controllability. The paper also addresses the complex interactions between these cognitive attributes, emotional distress and preventive health behaviour.

Subordinated continuous-time AR processes and their application to modeling behavior of mechanical system

NASA Astrophysics Data System (ADS)

Gajda, Janusz; Wyłomańska, Agnieszka; Zimroz, Radosław

2016-12-01

Many real data exhibit behavior adequate to subdiffusion processes. Very often it is manifested by so-called ;trapping events;. The visible evidence of subdiffusion we observe not only in financial time series but also in technical data. In this paper we propose a model which can be used for description of such kind of data. The model is based on the continuous time autoregressive time series with stable noise delayed by the infinitely divisible inverse subordinator. The proposed system can be applied to real datasets with short-time dependence, visible jumps and mentioned periods of stagnation. In this paper we extend the theoretical considerations in analysis of subordinated processes and propose a new model that exhibits mentioned properties. We concentrate on the main characteristics of the examined subordinated process expressed mainly in the language of the measures of dependence which are main tools used in statistical investigation of real data. We present also the simulation procedure of the considered system and indicate how to estimate its parameters. The theoretical results we illustrate by the analysis of real technical data.

The Reinforcement Sensitivity Theory of Personality Questionnaire (RST-PQ): Development and validation.

PubMed

Corr, Philip J; Cooper, Andrew J

2016-11-01

We report the development and validation of a questionnaire measure of the revised reinforcement sensitivity theory (rRST) of personality. Starting with qualitative responses to defensive and approach scenarios modeled on typical rodent ethoexperimental situations, exploratory and confirmatory factor analyses (CFAs) revealed a robust 6-factor structure: 2 unitary defensive factors, fight-flight-freeze system (FFFS; related to fear) and the behavioral inhibition system (BIS; related to anxiety); and 4 behavioral approach system (BAS) factors (Reward Interest, Goal-Drive Persistence, Reward Reactivity, and Impulsivity). Theoretically motivated thematic facets were employed to sample the breadth of defensive space, comprising FFFS (Flight, Freeze, and Active Avoidance) and BIS (Motor Planning Interruption, Worry, Obsessive Thoughts, and Behavioral Disengagement). Based on theoretical considerations, and statistically confirmed, a separate scale for Defensive Fight was developed. Validation evidence for the 6-factor structure came from convergent and discriminant validity shown by correlations with existing personality scales. We offer the Reinforcement Sensitivity Theory of Personality Questionnaire to facilitate future research specifically on rRST and, more broadly, on approach-avoidance theories of personality. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

The variation in engine power with altitude determined from measurements in flight with a hub dynamometer

NASA Technical Reports Server (NTRS)

Gove, W D

1929-01-01

The rate of change in power of aircraft engines with altitude has been the subject of considerable discussion. Only a small amount of data from direct measurements of the power delivered by airplane engines during flight, however, has been published. This report presents the results of direct measurements of the power delivered by a Liberty 12 airplane engine taken with a hub dynamometer at standard altitudes from zero to 13,000 feet. Six flights were made with the engine installed in a modified DH-4 airplane. The experimental relation of brake horsepower to altitude is compared with two theoretical relations and with the experimental results, for a second Liberty 12 engine, given in NACA Technical Report no. 252. The rate of change in power with altitude of a third Liberty engine, measured with a calibrated propeller, is also given for comparison. The data presented substantiate the theoretical relation of brake horsepower to altitude based on the correction of ground level indicated horsepower for change in atmospheric temperature and pressure with the subsequent deduction of friction horsepower corrected for altitude. (author)

Coarse-graining errors and numerical optimization using a relative entropy framework

NASA Astrophysics Data System (ADS)

Chaimovich, Aviel; Shell, M. Scott

2011-03-01

The ability to generate accurate coarse-grained models from reference fully atomic (or otherwise "first-principles") ones has become an important component in modeling the behavior of complex molecular systems with large length and time scales. We recently proposed a novel coarse-graining approach based upon variational minimization of a configuration-space functional called the relative entropy, Srel, that measures the information lost upon coarse-graining. Here, we develop a broad theoretical framework for this methodology and numerical strategies for its use in practical coarse-graining settings. In particular, we show that the relative entropy offers tight control over the errors due to coarse-graining in arbitrary microscopic properties, and suggests a systematic approach to reducing them. We also describe fundamental connections between this optimization methodology and other coarse-graining strategies like inverse Monte Carlo, force matching, energy matching, and variational mean-field theory. We suggest several new numerical approaches to its minimization that provide new coarse-graining strategies. Finally, we demonstrate the application of these theoretical considerations and algorithms to a simple, instructive system and characterize convergence and errors within the relative entropy framework.

Kinetics and equilibrium of solute diffusion into human hair.

PubMed

Wang, Liming; Chen, Longjian; Han, Lujia; Lian, Guoping

2012-12-01

The uptake kinetics of five molecules by hair has been measured and the effects of pH and physical chemical properties of molecules were investigated. A theoretical model is proposed to analyze the experimental data. The results indicate that the binding affinity of solute to hair, as characterized by hair-water partition coefficient, scales to the hydrophobicity of the solute and decreases dramatically as the pH increases to the dissociation constant. The effective diffusion coefficient of solute depended not only on the molecular size as most previous studies suggested, but also on the binding affinity as well as solute dissociation. It appears that the uptake of molecules by hair is due to both hydrophobic interaction and ionic charge interaction. Based on theoretical considerations of the cellular structure, composition and physical chemical properties of hair, quantitative-structure-property-relationships (QSPR) have been proposed to predict the hair-water partition coefficient (PC) and the effective diffusion coefficient (D (e)) of solute. The proposed QSPR models fit well with the experimental data. This paper could be taken as a reference for investigating the adsorption properties for polymeric materials, fibres, and biomaterials.

Travel-related thrombosis.

PubMed

Cannegieter, Suzanne C

2012-09-01

Travel-related thrombosis is a serious public health concern considering the large and increasing number of travellers. Due to a lack of evidence, counselling air travellers on their venous thrombosis risk is not immediately straightforward, and advice will have to be based mostly on theoretical grounds. In this review a basis for these considerations is given. First of all it needs to be recognized that venous thrombosis is a multicausal disease, i.e. several risk factors have to be present before an event occurs. This is reflected in the literature where clearly increased risks have been described for certain groups, such as subjects with factor V Leiden, those who use oral contraceptives or are obese. Also, an increased risk for tall and short people has been reported. So, for subjects with a known risk factor who plan to travel, benefits and risks of thrombosis prophylaxis, (pharmacological or other), need to be weighed. This review provides some theoretical examples. For all other travellers, the advice to move and exercise as much as possible is likely to be sufficient. Copyright © 2012. Published by Elsevier Ltd.

The influence of dynamical change of optical properties on the thermomechanical response and damage threshold of noble metals under femtosecond laser irradiation

NASA Astrophysics Data System (ADS)

Tsibidis, George D.

2018-02-01

We present a theoretical investigation of the dynamics of the dielectric constant of noble metals following heating with ultrashort pulsed laser beams and the influence of the temporal variation of the associated optical properties on the thermomechanical response of the material. The effect of the electron relaxation time on the optical properties based on the use of a critical point model is thoroughly explored for various pulse duration values (i.e., from 110 fs to 8 ps). The proposed theoretical framework correlates the dynamical change in optical parameters, relaxation processes and induced strains-stresses. Simulations are presented by choosing gold as a test material, and we demonstrate that the consideration of the aforementioned factors leads to significant thermal effect changes compared to results when static parameters are assumed. The proposed model predicts a substantially smaller damage threshold and a large increase of the stress which firstly underlines the significant role of the temporal variation of the optical properties and secondly enhances its importance with respect to the precise determination of laser specifications in material micromachining techniques.

Global Human Footprint on the Linkage between Biodiversity and Ecosystem Functioning in Reef Fishes

PubMed Central

Mora, Camilo; Aburto-Oropeza, Octavio; Ayala Bocos, Arturo; Ayotte, Paula M.; Banks, Stuart; Bauman, Andrew G.; Beger, Maria; Bessudo, Sandra; Booth, David J.; Brokovich, Eran; Brooks, Andrew; Chabanet, Pascale; Cinner, Joshua E.; Cortés, Jorge; Cruz-Motta, Juan J.; Cupul Magaña, Amilcar; DeMartini, Edward E.; Edgar, Graham J.; Feary, David A.; Ferse, Sebastian C. A.; Friedlander, Alan M.; Gaston, Kevin J.; Gough, Charlotte; Graham, Nicholas A. J.; Green, Alison; Guzman, Hector; Hardt, Marah; Kulbicki, Michel; Letourneur, Yves; López Pérez, Andres; Loreau, Michel; Loya, Yossi; Martinez, Camilo; Mascareñas-Osorio, Ismael; Morove, Tau; Nadon, Marc-Olivier; Nakamura, Yohei; Paredes, Gustavo; Polunin, Nicholas V. C.; Pratchett, Morgan S.; Reyes Bonilla, Héctor; Rivera, Fernando; Sala, Enric; Sandin, Stuart A.; Soler, German; Stuart-Smith, Rick; Tessier, Emmanuel; Tittensor, Derek P.; Tupper, Mark; Usseglio, Paolo; Vigliola, Laurent; Wantiez, Laurent; Williams, Ivor; Wilson, Shaun K.; Zapata, Fernando A.

2011-01-01

Difficulties in scaling up theoretical and experimental results have raised controversy over the consequences of biodiversity loss for the functioning of natural ecosystems. Using a global survey of reef fish assemblages, we show that in contrast to previous theoretical and experimental studies, ecosystem functioning (as measured by standing biomass) scales in a non-saturating manner with biodiversity (as measured by species and functional richness) in this ecosystem. Our field study also shows a significant and negative interaction between human population density and biodiversity on ecosystem functioning (i.e., for the same human density there were larger reductions in standing biomass at more diverse reefs). Human effects were found to be related to fishing, coastal development, and land use stressors, and currently affect over 75% of the world's coral reefs. Our results indicate that the consequences of biodiversity loss in coral reefs have been considerably underestimated based on existing knowledge and that reef fish assemblages, particularly the most diverse, are greatly vulnerable to the expansion and intensity of anthropogenic stressors in coastal areas. PMID:21483714

Plant delta 15N correlates with the transpiration efficiency of nitrogen acquisition in tropical trees.

PubMed

Cernusak, Lucas A; Winter, Klaus; Turner, Benjamin L

2009-11-01

Based upon considerations of a theoretical model of (15)N/(14)N fractionation during steady-state nitrate uptake from soil, we hypothesized that, for plants grown in a common soil environment, whole-plant delta(15)N (deltaP) should vary as a function of the transpiration efficiency of nitrogen acquisition (F(N)/v) and the difference between deltaP and root delta(15)N (deltaP - deltaR). We tested these hypotheses with measurements of several tropical tree and liana species. Consistent with theoretical expectations, both F(N)/v and deltaP - deltaR were significant sources of variation in deltaP, and the relationship between deltaP and F(N)/v differed between non-N(2)-fixing and N(2)-fixing species. We interpret the correlation between deltaP and F(N)/v as resulting from variation in mineral nitrogen efflux-to-influx ratios across plasma membranes of root cells. These results provide a simple explanation of variation in delta(15)N of terrestrial plants and have implications for understanding nitrogen cycling in ecosystems.

On Mathematical Modeling Of Quantum Systems

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

Achuthan, P.; Dept. of Mathematics, Indian Institute of Technology, Madras, 600 036; Narayanankutty, Karuppath

2009-07-02

The world of physical systems at the most fundamental levels is replete with efficient, interesting models possessing sufficient ability to represent the reality to a considerable extent. So far, quantum mechanics (QM) forming the basis of almost all natural phenomena, has found beyond doubt its intrinsic ingenuity, capacity and robustness to stand the rigorous tests of validity from and through appropriate calculations and experiments. No serious failures of quantum mechanical predictions have been reported, yet. However, Albert Einstein, the greatest theoretical physicist of the twentieth century and some other eminent men of science have stated firmly and categorically that QM,more » though successful by and large, is incomplete. There are classical and quantum reality models including those based on consciousness. Relativistic quantum theoretical approaches to clearly understand the ultimate nature of matter as well as radiation have still much to accomplish in order to qualify for a final theory of everything (TOE). Mathematical models of better, suitable character as also strength are needed to achieve satisfactory explanation of natural processes and phenomena. We, in this paper, discuss some of these matters with certain apt illustrations as well.« less

Multiple neural states of representation in short-term memory? It's a matter of attention.

PubMed

Larocque, Joshua J; Lewis-Peacock, Jarrod A; Postle, Bradley R

2014-01-01

Short-term memory (STM) refers to the capacity-limited retention of information over a brief period of time, and working memory (WM) refers to the manipulation and use of that information to guide behavior. In recent years it has become apparent that STM and WM interact and overlap with other cognitive processes, including attention (the selection of a subset of information for further processing) and long-term memory (LTM-the encoding and retention of an effectively unlimited amount of information for a much longer period of time). Broadly speaking, there have been two classes of memory models: systems models, which posit distinct stores for STM and LTM (Atkinson and Shiffrin, 1968; Baddeley and Hitch, 1974); and state-based models, which posit a common store with different activation states corresponding to STM and LTM (Cowan, 1995; McElree, 1996; Oberauer, 2002). In this paper, we will focus on state-based accounts of STM. First, we will consider several theoretical models that postulate, based on considerable behavioral evidence, that information in STM can exist in multiple representational states. We will then consider how neural data from recent studies of STM can inform and constrain these theoretical models. In the process we will highlight the inferential advantage of multivariate, information-based analyses of neuroimaging data (fMRI and electroencephalography (EEG)) over conventional activation-based analysis approaches (Postle, in press). We will conclude by addressing lingering questions regarding the fractionation of STM, highlighting differences between the attention to information vs. the retention of information during brief memory delays.

Evidence-based interventions for reading and language difficulties: creating a virtuous circle.

PubMed

Snowling, Margaret J; Hulme, Charles

2011-03-01

BACKGROUND. Children may experience two very different forms of reading problem: decoding difficulties (dyslexia) and reading comprehension difficulties. Decoding difficulties appear to be caused by problems with phonological (speech sound) processing. Reading comprehension difficulties in contrast appear to be caused by problems with 'higher level' language difficulties including problems with semantics (including deficient knowledge of word meanings) and grammar (knowledge of morphology and syntax). AIMS. We review evidence concerning the nature, causes of, and treatments for children's reading difficulties. We argue that any well-founded educational intervention must be based on a sound theory of the causes of a particular form of learning difficulty, which in turn must be based on an understanding of how a given skill is learned by typically developing children. Such theoretically motivated interventions should in turn be evaluated in randomized controlled trials (RCTs) to establish whether they are effective, and for whom. RESULTS. There is now considerable evidence showing that phonologically based interventions are effective in ameliorating children's word level decoding difficulties, and a smaller evidence base showing that reading and oral language (OL) comprehension difficulties can be ameliorated by suitable interventions to boost vocabulary and broader OL skills. CONCLUSIONS. The process of developing theories about the origins of children's educational difficulties and evaluating theoretically motivated treatments in RCTs, produces a 'virtuous circle' whereby theory informs practice, and the evaluation of effective interventions in turn feeds back to inform and refine theories about the nature and causes of children's reading and language difficulties. ©2010 The British Psychological Society.

Spherically-symmetric solutions in general relativity using a tetrad-based approach

NASA Astrophysics Data System (ADS)

Kim, Do Young; Lasenby, Anthony N.; Hobson, Michael P.

2018-03-01

We present a tetrad-based method for solving the Einstein field equations for spherically-symmetric systems and compare it with the widely-used Lemaître-Tolman-Bondi (LTB) model. In particular, we focus on the issues of gauge ambiguity and the use of comoving versus `physical' coordinate systems. We also clarify the correspondences between the two approaches, and illustrate their differences by applying them to the classic examples of the Schwarzschild and Friedmann-Lemaître-Robertson-Walker spacetimes. We demonstrate that the tetrad-based method does not suffer from the gauge freedoms inherent to the LTB model, naturally accommodates non-uniform pressure and has a more transparent physical interpretation. We further apply our tetrad-based method to a generalised form of `Swiss cheese' model, which consists of an interior spherical region surrounded by a spherical shell of vacuum that is embedded in an exterior background universe. In general, we allow the fluid in the interior and exterior regions to support pressure, and do not demand that the interior region be compensated. We pay particular attention to the form of the solution in the intervening vacuum region and illustrate the validity of Birkhoff's theorem at both the metric and tetrad level. We then reconsider critically the original theoretical arguments underlying the so-called Rh = ct cosmological model, which has recently received considerable attention. These considerations in turn illustrate the interesting behaviour of a number of `horizons' in general cosmological models.

Theoretical Noise Analysis on a Position-sensitive Metallic Magnetic Calorimeter

NASA Technical Reports Server (NTRS)

Smith, Stephen J.

2007-01-01

We report on the theoretical noise analysis for a position-sensitive Metallic Magnetic Calorimeter (MMC), consisting of MMC read-out at both ends of a large X-ray absorber. Such devices are under consideration as alternatives to other cryogenic technologies for future X-ray astronomy missions. We use a finite-element model (FEM) to numerically calculate the signal and noise response at the detector outputs and investigate the correlations between the noise measured at each MMC coupled by the absorber. We then calculate, using the optimal filter concept, the theoretical energy and position resolution across the detector and discuss the trade-offs involved in optimizing the detector design for energy resolution, position resolution and count rate. The results show, theoretically, the position-sensitive MMC concept offers impressive spectral and spatial resolving capabilities compared to pixel arrays and similar position-sensitive cryogenic technologies using Transition Edge Sensor (TES) read-out.

Missing energies at pair creation

NASA Technical Reports Server (NTRS)

El-Ela, A. A.; Hassan, S.; Bagge, E. R.

1985-01-01

Wilson cloud chamber measurements of the separated spectra of positrons and electrons produced by gamma quanta of 6.14 MeV differ considerably from the theoretically predicted spectra by BETHE and HEITLER, but are in good agreement with those of a modified theory of pair creation.

Method to enhance the performance of synthetic origin-destination (O-D) trip table estimation models.

DOT National Transportation Integrated Search

1998-01-01

The conventional methods of determining origin-destination (O-D) trip tables involve elaborate surveys, e.g., home interviews, that require considerable time, staff, and funds. To overcome this drawback, a number of theoretical models that synthesize...

The Value of Inclusion

ERIC Educational Resources Information Center

Felder, Franziska

2018-01-01

In recent years inclusion has become one of the most dominant values and objectives in education. However, there is still considerable disagreement concerning the theoretical concept of inclusion and its normative implications. This article suggests an understanding of inclusion that first differentiates analytically between societal and communal…

A comparison of theoretical and experimental pressure distributions for two advanced fighter wings

NASA Technical Reports Server (NTRS)

Haney, H. P.; Hicks, R. M.

1981-01-01

A comparison was made between experimental pressure distributions measured during testing of the Vought A-7 fighter and the theoretical predictions of four transonic potential flow codes. Isolated wind and three wing-body codes were used for comparison. All comparisons are for transonic Mach numbers and include both attached and separate flows. In general, the wing-body codes gave better agreement with the experiment than did the isolated wing code but, because of the greater complexity of the geometry, were found to be considerably more expensive and less reliable.

Nurses' tending instinct as a conduit for men's access to mental health counseling.

PubMed

Smith, Jeffrey M; Robertson, Steve

2006-06-01

No article has been found melding the phenomenon of nurses' tending instinct and men's mental health counseling access. This theoretical article presents nurses' tending instinct as a viable rationale to support men in utilizing mental health counseling services. Nurses can be the conduit that assists men in accessing mental health counseling when the need arises. An amalgamation of related topics, including nurses' tending instinct, men's illness/injury/disease profile, psychological medicine, and counselor skills, were forged together to unify this innovative theoretical consideration. Implications for nursing practice also were explored.

Numerical and Theoretical Considerations for the Design of the AVT-183 Diamond-Wing Experimental Investigations

NASA Technical Reports Server (NTRS)

Boelens, Okko J.; Luckring, James M.; Breitsamter, Christian; Hovelmann, Andreas; Knoth, Florian; Malloy, Donald J.; Deck, Sebatien

2015-01-01

A diamond-wing configuration has been developed to isolate and study blunt-leading edge vortex separation with both computations and experiments. The wing has been designed so that the results are relevant to a more complex Uninhabited Combat Air Vehicle concept known as SACCON. The numerical and theoretical development process for this diamond wing is presented, including a view toward planned wind tunnel experiments. This work was conducted under the NATO Science and Technology Organization, Applied Vehicle Technology panel. All information is in the public domain.

Solar neutrinos and the MSW effect for three-neutrino mixing

NASA Technical Reports Server (NTRS)

Shi, X.; Schramm, David N.

1991-01-01

Researchers considered three-neutrino Mikheyev-Smirnov-Wolfenstein (MSW) mixing, assuming m sub 3 is much greater than m sub 2 is greater than m sub 1 as expected from theoretical consideration if neutrinos have mass. They calculated the corresponding mixing parameter space allowed by the Cl-37 and Kamiokande 2 experiments. They also calculated the expected depletion for the Ga-71 experiment. They explored a range of theoretical uncertainty due to possible astrophysical effects by varying the B-8 neutrino flux and redoing the MSW mixing calculation.

Modelling Catalyst Surfaces Using DFT Cluster Calculations

PubMed Central

Czekaj, Izabela; Wambach, Jörg; Kröcher, Oliver

2009-01-01

We review our recent theoretical DFT cluster studies of a variety of industrially relevant catalysts such as TiO2, γ-Al2O3, V2O5-WO3-TiO2 and Ni/Al2O3. Aspects of the metal oxide surface structure and the stability and structure of metal clusters on the support are discussed as well as the reactivity of surfaces, including their behaviour upon poisoning. It is exemplarily demonstrated how such theoretical considerations can be combined with DRIFT and XPS results from experimental studies. PMID:20057947

A probabilistic analysis of electrical equipment vulnerability to carbon fibers

NASA Technical Reports Server (NTRS)

Elber, W.

1980-01-01

The statistical problems of airborne carbon fibers falling onto electrical circuits were idealized and analyzed. The probability of making contact between randomly oriented finite length fibers and sets of parallel conductors with various spacings and lengths was developed theoretically. The probability of multiple fibers joining to bridge a single gap between conductors, or forming continuous networks is included. From these theoretical considerations, practical statistical analyses to assess the likelihood of causing electrical malfunctions was produced. The statistics obtained were confirmed by comparison with results of controlled experiments.

Catalytic Hydrogenation of Carbon Dioxide with Ammonia-Borane by Pincer-type Phosphorus Compound: A Theoretical Prediction.

PubMed

Zeng, Guixiang; Maeda, Satoshi; Taketsugu, Tetsuya; Sakaki, Shigeyoshi

2016-10-01

Theoretically designed pincer-type phosphorus compound is found to be active for the hydrogenation of carbon dioxide (CO 2 ) with ammonia-borane. DFT, ONIOM(CCSD(T):MP2), and CCSD(T) computational results demonstrated that the reaction occurs through the phosphorus-ligand cooperative catalysis function, which provides an unprecedented protocol for metal-free CO 2 conversion. The phosphorus compounds with the NNN ligand are more active than those with the ONO ligand. The conjugate and planar ligand considerably improves the efficiency of the catalyst.

Bicarbonate Values for Healthy Residents Living in Cities Above 1500 Meters of Altitude: A Theoretical Model and Systematic Review.

PubMed

Ramirez-Sandoval, Juan C; Castilla-Peón, Maria F; Gotés-Palazuelos, José; Vázquez-García, Juan C; Wagner, Michael P; Merelo-Arias, Carlos A; Vega-Vega, Olynka; Rincón-Pedrero, Rodolfo; Correa-Rotter, Ricardo

2016-06-01

Ramirez-Sandoval, Juan C., Maria F. Castilla-Peón, José Gotés-Palazuelos, Juan C. Vázquez-García, Michael P. Wagner, Carlos A. Merelo-Arias, Olynka Vega-Vega, Rodolfo Rincón-Pedrero, and Ricardo Correa-Rotter. Bicarbonate values for healthy residents living in cities above 1500 m of altitude: a theoretical model and systematic review. High Alt Med Biol. 17:85-92, 2016.-Plasma bicarbonate (HCO3(-)) concentration is the main value used to assess the metabolic component of the acid-base status. There is limited information regarding plasma HCO3(-) values adjusted for altitude for people living in cities at high altitude defined as 1500 m (4921 ft) or more above sea level. Our aim was to estimate the plasma HCO3(-) concentration in residents of cities at these altitudes using a theoretical model and compare these values with HCO3(-) values found on a systematic review, and with those venous CO2 values obtained in a sample of 633 healthy individuals living at an altitude of 2240 m (7350 ft). We calculated the PCO2 using linear regression models and calculated plasma HCO3(-) according to the Henderson-Hasselbalch equation. Results show that HCO3(-) concentration falls as the altitude of the cities increase. For each 1000 m of altitude above sea level, HCO3(-) decreases to 0.55 and 1.5 mEq/L in subjects living at sea level with acute exposure to altitude and in subjects acclimatized to altitude, respectively. Estimated HCO3(-) values from the theoretical model were not different to HCO3(-) values found in publications of a systematic review or with venous total CO2 measurements in our sample. Altitude has to be taken into consideration in the calculation of HCO3(-) concentrations in cities above 1500 m to avoid an overdiagnosis of acid-base disorders in a given individual.

Nature of the optical band shapes in polymethine dyes and H-aggregates: dozy chaos and excitons. Comparison with dimers, H*- and J-aggregates.

PubMed

Egorov, Vladimir V

2017-05-01

Results on the theoretical explanation of the shape of optical bands in polymethine dyes, their dimers and aggregates are summarized. The theoretical dependence of the shape of optical bands for the dye monomers in the vinylogous series in line with a change in the solvent polarity is considered. A simple physical (analytical) model of the shape of optical absorption bands in H-aggregates of polymethine dyes is developed based on taking the dozy-chaos dynamics of the transient state and the Frenkel exciton effect in the theory of molecular quantum transitions into account. As an example, the details of the experimental shape of one of the known H-bands are well reproduced by this analytical model under the assumption that the main optical chromophore of H-aggregates is a tetramer resulting from the two most probable processes of inelastic binary collisions in sequence: first, monomers between themselves, and then, between the resulting dimers. The obtained results indicate that in contrast with the compact structure of J-aggregates (brickwork structure), the structure of H-aggregates is not the compact pack-of-cards structure, as stated in the literature, but a loose alternate structure. Based on this theoretical model, a simple general (analytical) method for treating the more complex shapes of optical bands in polymethine dyes in comparison with the H-band under consideration is proposed. This method mirrors the physical process of molecular aggregates forming in liquid solutions: aggregates are generated in the most probable processes of inelastic multiple binary collisions between polymethine species generally differing in complexity. The results obtained are given against a background of the theoretical results on the shape of optical bands in polymethine dyes and their aggregates (dimers, H*- and J-aggregates) previously obtained by V.V.E.

Nature of the optical band shapes in polymethine dyes and H-aggregates: dozy chaos and excitons. Comparison with dimers, H*- and J-aggregates

PubMed Central

2017-01-01

Results on the theoretical explanation of the shape of optical bands in polymethine dyes, their dimers and aggregates are summarized. The theoretical dependence of the shape of optical bands for the dye monomers in the vinylogous series in line with a change in the solvent polarity is considered. A simple physical (analytical) model of the shape of optical absorption bands in H-aggregates of polymethine dyes is developed based on taking the dozy-chaos dynamics of the transient state and the Frenkel exciton effect in the theory of molecular quantum transitions into account. As an example, the details of the experimental shape of one of the known H-bands are well reproduced by this analytical model under the assumption that the main optical chromophore of H-aggregates is a tetramer resulting from the two most probable processes of inelastic binary collisions in sequence: first, monomers between themselves, and then, between the resulting dimers. The obtained results indicate that in contrast with the compact structure of J-aggregates (brickwork structure), the structure of H-aggregates is not the compact pack-of-cards structure, as stated in the literature, but a loose alternate structure. Based on this theoretical model, a simple general (analytical) method for treating the more complex shapes of optical bands in polymethine dyes in comparison with the H-band under consideration is proposed. This method mirrors the physical process of molecular aggregates forming in liquid solutions: aggregates are generated in the most probable processes of inelastic multiple binary collisions between polymethine species generally differing in complexity. The results obtained are given against a background of the theoretical results on the shape of optical bands in polymethine dyes and their aggregates (dimers, H*- and J-aggregates) previously obtained by V.V.E. PMID:28572984

Nature of the optical band shapes in polymethine dyes and H-aggregates: dozy chaos and excitons. Comparison with dimers, H*- and J-aggregates

NASA Astrophysics Data System (ADS)

Egorov, Vladimir V.

2017-05-01

Results on the theoretical explanation of the shape of optical bands in polymethine dyes, their dimers and aggregates are summarized. The theoretical dependence of the shape of optical bands for the dye monomers in the vinylogous series in line with a change in the solvent polarity is considered. A simple physical (analytical) model of the shape of optical absorption bands in H-aggregates of polymethine dyes is developed based on taking the dozy-chaos dynamics of the transient state and the Frenkel exciton effect in the theory of molecular quantum transitions into account. As an example, the details of the experimental shape of one of the known H-bands are well reproduced by this analytical model under the assumption that the main optical chromophore of H-aggregates is a tetramer resulting from the two most probable processes of inelastic binary collisions in sequence: first, monomers between themselves, and then, between the resulting dimers. The obtained results indicate that in contrast with the compact structure of J-aggregates (brickwork structure), the structure of H-aggregates is not the compact pack-of-cards structure, as stated in the literature, but a loose alternate structure. Based on this theoretical model, a simple general (analytical) method for treating the more complex shapes of optical bands in polymethine dyes in comparison with the H-band under consideration is proposed. This method mirrors the physical process of molecular aggregates forming in liquid solutions: aggregates are generated in the most probable processes of inelastic multiple binary collisions between polymethine species generally differing in complexity. The results obtained are given against a background of the theoretical results on the shape of optical bands in polymethine dyes and their aggregates (dimers, H*- and J-aggregates) previously obtained by V.V.E.

Proceedings of the Galactic Center Workshop 2002: The Central 300 Parsecs of the Milky Way. Astronomische Nachrichten Supplementary Issue 1/2003

NASA Astrophysics Data System (ADS)

Cotera, Angela; Markoff, Sera; Geballe, T. R.; Falcke, Heino

2004-03-01

Our knowledge of the environment of the nucleus of our galaxy has been greatly enhanced, by more extensive and sensitive observations at radio and infrared wavelengths, the advent of high resolution x-ray imaging and spectroscopy, and considerable theoretical activity to understand the nucleus and its components, and their activity. The Galactic Center Workshop 2002 was organized to review recent research on the galactic center, including the latest state-of-the-art observations and important theoretical developments. The workshop covered phenomena on scales ranging from the central several hundred parsecs to the central parsec and within. Each topic was approached from both multi-wavelength observational and theoretical perspectives.

Neuropsychological, Cognitive, and Theoretical Considerations for Evaluation of Bilingual Individuals

PubMed Central

Mindt, Monica Rivera; Arentoft, Alyssa; Germano, Kaori Kubo; D'Aquila, Erica; Scheiner, Diane; Pizzirusso, Maria; Sandoval, Tiffany C.; Gollan, Tamar H.

2008-01-01

As the number of bilinguals in the USA grows rapidly, it is increasingly important for neuropsychologists to be equipped and trained to address the unique challenges inherent in conducting ethical and competent neuropsychological evaluations with this population. Research on bilingualism has focused on two key cognitive mechanisms that introduce differences between bilinguals and monolinguals: (a) reduced frequency of language-specific use (weaker links), and (b) competition for selection within the language system in bilinguals (interference). Both mechanisms are needed to explain how bilingualism affects neuropsychological test performance, including the robust bilingual disadvantages found on verbal tasks, and more subtle bilingual advantages on some measures of cognitive control. These empirical results and theoretical claims can be used to derive a theoretically informed method for assessing cognitive status in bilinguals. We present specific considerations for measuring degree of bilingualism for both clients and examiners to aid in determinations of approaches to testing bilinguals, with practical guidelines for incorporating models of bilingualism and recent experimental data into neuropsychological evaluations. This integrated approach promises to provide improved clinical services for bilingual clients, and will also contribute to a program of research that will ultimately reveal the mechanisms underlying language processing and executive functioning in bilinguals and monolinguals alike. PMID:18841477

Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures

DOE PAGES

Caskey, Christopher M.; Holder, Aaron; Shulda, Sarah; ...

2016-04-12

Recent advances in theoretical structure prediction methods and high-throughput computational techniques are revolutionizing experimental discovery of the thermodynamically stable inorganic materials. Metastable materials represent a new frontier for these studies, since even simple binary non-ground state compounds of common elements may be awaiting discovery. However, there are significant research challenges related to non-equilibrium thin film synthesis and crystal structure predictions, such as small strained crystals in the experimental samples and energy minimization based theoretical algorithms. Here, we report on experimental synthesis and characterization, as well as theoretical first-principles calculations of a previously unreported mixed-valent binary tin nitride. Thin film experimentsmore » indicate that this novel material is N-deficient SnN with tin in the mixed ii/iv valence state and a small low-symmetry unit cell. Theoretical calculations suggest that the most likely crystal structure has the space group 2 (SG2) related to the distorted delafossite (SG166), which is nearly 0.1 eV/atom above the ground state SnN polymorph. Furthermore, this observation is rationalized by the structural similarity of the SnN distorted delafossite to the chemically related Sn 3N 4 spinel compound, which provides a fresh scientific insight into the reasons for growth of polymorphs of metastable materials. In addition to reporting on the discovery of the simple binary SnN compound, this paper illustrates a possible way of combining a wide range of advanced characterization techniques with the first-principle property calculation methods, to elucidate the most likely crystal structure of the previously unreported metastable materials.« less

Dream-reality confusion in borderline personality disorder: a theoretical analysis

PubMed Central

Skrzypińska, Dagna; Szmigielska, Barbara

2015-01-01

This paper presents an analysis of dream-reality confusion (DRC) in relation to the characteristics of borderline personality disorder (BPD), based on research findings and theoretical considerations. It is hypothesized that people with BPD are more likely to experience DRC compared to people in non-clinical population. Several variables related to this hypothesis were identified through a theoretical analysis of the scientific literature. Sleep disturbances: problems with sleep are found in 15–95.5% of people with BPD (Hafizi, 2013), and unstable sleep and wake cycles, which occur in BPD (Fleischer et al., 2012), are linked to DRC. Dissociation: nearly two-thirds of people with BPD experience dissociative symptoms (Korzekwa and Pain, 2009) and dissociative symptoms are correlated with a fantasy proneness; both dissociative symptoms and fantasy proneness are related to DRC (Giesbrecht and Merckelbach, 2006). Negative dream content: People with BPD have nightmares more often than other people (Semiz et al., 2008); dreams that are more likely to be confused with reality tend to be more realistic and unpleasant, and are reflected in waking behavior (Rassin et al., 2001). Cognitive disturbances: Many BPD patients experience various cognitive disturbances, including problems with reality testing (Fiqueierdo, 2006; Mosquera et al., 2011), which can foster DRC. Thin boundaries: People with thin boundaries are more prone to DRC than people with thick boundaries, and people with BPD tend to have thin boundaries (Hartmann, 2011). The theoretical analysis on the basis of these findings suggests that people who suffer from BPD may be more susceptible to confusing dream content with actual waking events. PMID:26441768

How cells engulf: a review of theoretical approaches to phagocytosis

NASA Astrophysics Data System (ADS)

Richards, David M.; Endres, Robert G.

2017-12-01

Phagocytosis is a fascinating process whereby a cell surrounds and engulfs particles such as bacteria and dead cells. This is crucial both for single-cell organisms (as a way of acquiring nutrients) and as part of the immune system (to destroy foreign invaders). This whole process is hugely complex and involves multiple coordinated events such as membrane remodelling, receptor motion, cytoskeleton reorganisation and intracellular signalling. Because of this, phagocytosis is an excellent system for theoretical study, benefiting from biophysical approaches combined with mathematical modelling. Here, we review these theoretical approaches and discuss the recent mathematical and computational models, including models based on receptors, models focusing on the forces involved, and models employing energetic considerations. Along the way, we highlight a beautiful connection to the physics of phase transitions, consider the role of stochasticity, and examine links between phagocytosis and other types of endocytosis. We cover the recently discovered multistage nature of phagocytosis, showing that the size of the phagocytic cup grows in distinct stages, with an initial slow stage followed by a much quicker second stage starting around half engulfment. We also address the issue of target shape dependence, which is relevant to both pathogen infection and drug delivery, covering both one-dimensional and two-dimensional results. Throughout, we pay particular attention to recent experimental techniques that continue to inform the theoretical studies and provide a means to test model predictions. Finally, we discuss population models, connections to other biological processes, and how physics and modelling will continue to play a key role in future work in this area.

Enactive Approach and Dual-Tasks for the Treatment of Severe Behavioral and Cognitive Impairment in a Person with Acquired Brain Injury: A Case Study.

PubMed

Martínez-Pernía, David; Huepe, David; Huepe-Artigas, Daniela; Correia, Rut; García, Sergio; Beitia, María

2016-01-01

One of the most important sequela in persons who suffer from acquired brain injury is a behavioral disorder. To date, the primary approaches for the rehabilitation of this sequela are Applied Behavior Analysis, Cognitive-Behavior Therapy, and Comprehensive-Holistic Rehabilitation Programs. Despite this theoretical plurality, none of these approaches focuses on rehabilitating behavioral disorders considering the relation between affordance and environmental adaptation. To introduce this therapeutic view to neurorehabilitation, we apply the theoretical tenets of the enactive paradigm to the rehabilitation of a woman with severe behavioral and cognitive impairment. Over seventeen sessions, her behavioral and cognitive performance was assessed in relation to two seated affordances (seated on a chair and seated on a ball 65 cm in diameter) and the environmental adaptation while she was working on various cognitive tasks. These two seated affordances allowed to incorporate the theoretical assumptions of the enactive approach and to know how the behavior and the cognition were modified based on these two postural settings and the environmental adaptation. The findings indicate that the subject exhibited better behavioral (physical and verbal) and cognitive (matching success and complex task) performances when the woman worked on the therapeutic ball than when the woman was on the chair. The enactive paradigm applied in neurorehabilitation introduces a level of treatment that precedes behavior and cognition. This theoretical consideration allowed the discovery of a better relation between a seated affordance and the environmental adaptation for the improvement behavioral and cognitive performance in our case study.

Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures

NASA Astrophysics Data System (ADS)

Caskey, Christopher M.; Holder, Aaron; Shulda, Sarah; Christensen, Steven T.; Diercks, David; Schwartz, Craig P.; Biagioni, David; Nordlund, Dennis; Kukliansky, Alon; Natan, Amir; Prendergast, David; Orvananos, Bernardo; Sun, Wenhao; Zhang, Xiuwen; Ceder, Gerbrand; Ginley, David S.; Tumas, William; Perkins, John D.; Stevanovic, Vladan; Pylypenko, Svitlana; Lany, Stephan; Richards, Ryan M.; Zakutayev, Andriy

2016-04-01

Recent advances in theoretical structure prediction methods and high-throughput computational techniques are revolutionizing experimental discovery of the thermodynamically stable inorganic materials. Metastable materials represent a new frontier for these studies, since even simple binary non-ground state compounds of common elements may be awaiting discovery. However, there are significant research challenges related to non-equilibrium thin film synthesis and crystal structure predictions, such as small strained crystals in the experimental samples and energy minimization based theoretical algorithms. Here, we report on experimental synthesis and characterization, as well as theoretical first-principles calculations of a previously unreported mixed-valent binary tin nitride. Thin film experiments indicate that this novel material is N-deficient SnN with tin in the mixed ii/iv valence state and a small low-symmetry unit cell. Theoretical calculations suggest that the most likely crystal structure has the space group 2 (SG2) related to the distorted delafossite (SG166), which is nearly 0.1 eV/atom above the ground state SnN polymorph. This observation is rationalized by the structural similarity of the SnN distorted delafossite to the chemically related Sn3N4 spinel compound, which provides a fresh scientific insight into the reasons for growth of polymorphs of metastable materials. In addition to reporting on the discovery of the simple binary SnN compound, this paper illustrates a possible way of combining a wide range of advanced characterization techniques with the first-principle property calculation methods, to elucidate the most likely crystal structure of the previously unreported metastable materials.

Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures.

PubMed

Caskey, Christopher M; Holder, Aaron; Shulda, Sarah; Christensen, Steven T; Diercks, David; Schwartz, Craig P; Biagioni, David; Nordlund, Dennis; Kukliansky, Alon; Natan, Amir; Prendergast, David; Orvananos, Bernardo; Sun, Wenhao; Zhang, Xiuwen; Ceder, Gerbrand; Ginley, David S; Tumas, William; Perkins, John D; Stevanovic, Vladan; Pylypenko, Svitlana; Lany, Stephan; Richards, Ryan M; Zakutayev, Andriy

2016-04-14

Recent advances in theoretical structure prediction methods and high-throughput computational techniques are revolutionizing experimental discovery of the thermodynamically stable inorganic materials. Metastable materials represent a new frontier for these studies, since even simple binary non-ground state compounds of common elements may be awaiting discovery. However, there are significant research challenges related to non-equilibrium thin film synthesis and crystal structure predictions, such as small strained crystals in the experimental samples and energy minimization based theoretical algorithms. Here, we report on experimental synthesis and characterization, as well as theoretical first-principles calculations of a previously unreported mixed-valent binary tin nitride. Thin film experiments indicate that this novel material is N-deficient SnN with tin in the mixed ii/iv valence state and a small low-symmetry unit cell. Theoretical calculations suggest that the most likely crystal structure has the space group 2 (SG2) related to the distorted delafossite (SG166), which is nearly 0.1 eV/atom above the ground state SnN polymorph. This observation is rationalized by the structural similarity of the SnN distorted delafossite to the chemically related Sn3N4 spinel compound, which provides a fresh scientific insight into the reasons for growth of polymorphs of metastable materials. In addition to reporting on the discovery of the simple binary SnN compound, this paper illustrates a possible way of combining a wide range of advanced characterization techniques with the first-principle property calculation methods, to elucidate the most likely crystal structure of the previously unreported metastable materials.

Synthesis of a mixed-valent tin nitride and considerations of its possible crystal structures

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

Caskey, Christopher M.; Colorado School of Mines, Golden, Colorado 80401; Larix Chemical Science, Golden, Colorado 80401

2016-04-14

Recent advances in theoretical structure prediction methods and high-throughput computational techniques are revolutionizing experimental discovery of the thermodynamically stable inorganic materials. Metastable materials represent a new frontier for these studies, since even simple binary non-ground state compounds of common elements may be awaiting discovery. However, there are significant research challenges related to non-equilibrium thin film synthesis and crystal structure predictions, such as small strained crystals in the experimental samples and energy minimization based theoretical algorithms. Here, we report on experimental synthesis and characterization, as well as theoretical first-principles calculations of a previously unreported mixed-valent binary tin nitride. Thin film experimentsmore » indicate that this novel material is N-deficient SnN with tin in the mixed II/IV valence state and a small low-symmetry unit cell. Theoretical calculations suggest that the most likely crystal structure has the space group 2 (SG2) related to the distorted delafossite (SG166), which is nearly 0.1 eV/atom above the ground state SnN polymorph. This observation is rationalized by the structural similarity of the SnN distorted delafossite to the chemically related Sn{sub 3}N{sub 4} spinel compound, which provides a fresh scientific insight into the reasons for growth of polymorphs of metastable materials. In addition to reporting on the discovery of the simple binary SnN compound, this paper illustrates a possible way of combining a wide range of advanced characterization techniques with the first-principle property calculation methods, to elucidate the most likely crystal structure of the previously unreported metastable materials.« less

Evolution and Transport of Water in the Upper Regolith of Mars

NASA Technical Reports Server (NTRS)

Hudson, T. L.; Aharonson, O.; Schorghofer, N.; Hecht, M. H.; Bridges, N. T.; Green, J. R.

2003-01-01

Long standing theoretical predictions [1-3], as well as recent spacecraft observations [4] indicate that large quantities of ice is present in the high latitudes upper decimeters to meters of the Martian regolith. At shallower depths and warmer locations small amounts of H2O, either adsorbed or free, may be present transiently. An understanding of the evolution of water based on theoretical and experimental considerations of the processes operating at the Martian environment is required. In particular, the porosity, diffusivity, and permeability of soils and their effect on water vapor transport under Mars-like conditions have been estimated, but experimental validation of such models is lacking. Goal: Three related mechanisms may affect water transport in the upper Martian regolith. 1) diffusion along a concentration gradient under isobaric conditions, 2) diffusion along a thermal gradient, which may give rise to a concentration gradient as ice sublimes or molecules desorb from the regolith, and 3) hydraulic flow, or mass motion in response to a pressure gradient. Our combined theoretical and experimental investigation seeks to disentangle these mechanisms and determine which process(es) are dominant in the upper regolith over various timescales. A detailed one-dimensional model of the upper regolith is being created which incorporates water adsorption/ desorption, condensation, porosity, diffusivity, and permeability effects. Certain factors such as diffusivity are difficult to determine theoretically due to the wide range of intrinsic grain properties such as particle sizes, shapes, packing densities, and emergent properties such as tortuosity. An experiment is being designed which will allow us to more accurately determine diffusivity, permeability, and water desorption isotherms for regolith simulants.

Analysing and exemplifying forensic conclusion criteria in terms of Bayesian decision theory.

PubMed

Biedermann, A; Bozza, S; Taroni, F

2018-03-01

There is ongoing discussion in forensic science and the law about the nature of the conclusions reached based on scientific evidence, and on how such conclusions - and conclusion criteria - may be justified by rational argument. Examples, among others, are encountered in fields such as fingermarks (e.g., 'this fingermark comes from Mr. A's left thumb'), handwriting examinations (e.g., 'the questioned signature is that of Mr. A'), kinship analyses (e.g., 'Mr. A is the father of child C') or anthropology (e.g., 'these are human remains'). Considerable developments using formal methods of reasoning based on, for example (Bayesian) decision theory, are available in literature, but currently such reference principles are not explicitly used in operational forensic reporting and ensuing decision-making. Moreover, applied examples, illustrating the principles, are scarce. A potential consequence of this in practical proceedings, and hence a cause of concern, is that underlying ingredients of decision criteria (such as losses quantifying the undesirability of adverse decision consequences), are not properly dealt with. There is merit, thus, in pursuing the study and discussion of practical examples, demonstrating that formal decision-theoretic principles are not merely conceptual considerations. Actually, these principles can be shown to underpin practical decision-making procedures and existing legal decision criteria, though often not explicitly apparent as such. In this paper, we will present such examples and discuss their properties from a Bayesian decision-theoretic perspective. We will argue that these are essential concepts for an informed discourse on decision-making across forensic disciplines and the development of a coherent view on this topic. We will also emphasize that these principles are of normative nature in the sense that they provide standards against which actual judgment and decision-making may be compared. Most importantly, these standards are justified independently of peoples' observable decision behaviour, and of whether or not one endorses these formal methods of reasoning. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

The Bobath (NDT) concept in adult neurological rehabilitation: what is the state of the knowledge? A scoping review. Part I: conceptual perspectives.

PubMed

Vaughan-Graham, Julie; Cott, Cheryl; Wright, F Virginia

2015-01-01

The study's purpose was to describe the range of knowledge pertaining to the Bobath concept/NDT in adult neurological rehabilitation, synthesize the findings, identify knowledge gaps and develop empirically based recommendations for future research. This article explores the conceptual literature. A scoping review of research and non-research articles published from 2007 to 2012. Two independent reviewers selected studies based on a systematic procedure. Inclusion criteria for studies were: electronically accessible English language literature with Bobath and/or neurodevelopmental therapy (NDT) as the subject heading in the title/keyword/abstract/intervention comparison with respect to adult neurological conditions. Data were abstracted and summarized with respect to study purpose, defining and operationalizing the Bobath concept, therapist demographics, recruitment, discussion and conclusions. Of the 33 publications identified, 14 publications sought to define the theoretical foundations and identify key aspects of clinical practice of the contemporary Bobath concept. The publications comprised three theoretical papers, four surveys, a Delphi reported through two papers, one qualitative study, three letters to the editor and one editorial. Knowledge derived from review of the conceptual literature provides clinicians with an updated Bobath clinical framework as well as identifying aspects of Bobath clinical practice that require careful consideration in future effectiveness studies. Implications for Rehabilitation The integration of posture and movement with respect to the quality of task performance remains a cornerstone of the redefined Bobath concept. A key fundamental principle of the clinical application of the Bobath concept since its inception is the selective manipulation of sensory information, namely, facilitation, to positively affect motor control and perception in persons post-central nervous system lesion. This is an aspect of Bobath clinical practice that requires further investigation. Study and treatment fidelity issues such as therapist expertise, the use of treatment logs to document individualized clinical practice, as well as therapist supervision and evaluation require careful consideration in the implementation of Bobath effectiveness studies such that causality can be determined.

Optical cylinder designs to increase the field of vision in the osteo-odonto-keratoprosthesis.

PubMed

Hull, C C; Liu, C S; Sciscio, A; Eleftheriadis, H; Herold, J

2000-12-01

The single optical cylinders used in the osteo-odonto-keratoprosthesis (OOKP) are known to produce very small visual fields. Values of 40 degrees are typically quoted. The purpose of this paper is to present designs for new optical cylinders that significantly increase the field of view and therefore improve the visual rehabilitation of patients having an OOKP. Computer ray-tracing techniques were used to design and analyse improved one- and two-piece optical cylinders made from polymethyl methacrylate. All designs were required to have a potential visual acuity of 6/6 before consideration was given to the visual field and optimising off-axis image quality. Aspheric surfaces were used where this significantly improved off-axis image quality. Single optical cylinders, with increased posterior cylinder (intraocular) diameters, gave an increase in the theoretical visual field of 18% (from 76 degrees to 90 degrees) over current designs. Two-piece designs based on an inverted telephoto principle gave theoretical field angles over 120 degrees. Aspheric surfaces were shown to improve the off-axis image quality while maintaining a potential visual acuity of at least 6/6. This may well increase the measured visual field by improving the retinal illuminance off-axis. Results demonstrate that it is possible to significantly increase the theoretical maximum visual field through OOKP optical cylinders. Such designs will improve the visual rehabilitation of patients undergoing this procedure.

Active control of sound transmission through a double panel partition

NASA Astrophysics Data System (ADS)

Sas, P.; Bao, C.; Augusztinovicz, F.; Desmet, W.

1995-03-01

The feasibility of improving the insertion loss of lightweight double panel partitions by using small loudspeakers as active noise control sources inside the air gap between both panels of the partition is investigated analytically, numerically and experimentally in this paper. A theoretical analysis of the mechanisms of the fluid-structure interaction of double panel structures is presented in order to gain insight into the physical phenomena underlying the behaviour of a coupled vibro-acoustic system controlled by active methods. The analysis, based on modal coupling theory, enables one to derive some qualitative predictions concerning the potentials and limitations of the proposed approach. The theoretical analysis is valid only for geometrically simple structures. For more complex geometries, numerical simulations are required. Therefore the potential use of active noise control inside double panel structures has been analyzed by using coupled finite element and boundary element methods. To verify the conclusions drawn from the theoretical analysis and the numerical calculation and, above all, to demonstrate the potential of the proposed approach, experiments have been conducted with a laboratory set-up. The performance of the proposed approach was evaluated in terms of relative insertion loss measurements. It is shown that a considerable improvement of the insertion loss has been achieved around the lightly damped resonances of the system for the frequency range investigated (60-220 Hz).

Quantitative analysis of H-species in anisotropic minerals by polarized infrared spectroscopy along three orthogonal directions

NASA Astrophysics Data System (ADS)

Shuai, Kang; Yang, Xiaozhi

2017-03-01

Infrared spectroscopy is a powerful technique for probing H-species in nominally anhydrous minerals, and a particular goal of considerable efforts has been providing a simple yet accurate method for the quantification. The available methods, with either polarized or unpolarized analyses, are usually time-consuming or, in some cases, subjected to larger uncertainty than theoretically expected. It is shown here that an empirical approach for measuring the concentration, by determining three polarized infrared spectra along any three mutually perpendicular directions, is theoretically and in particular experimentally correct. The theoretical background is established by considering the integrated absorbance, and the experimental measurements are based on a careful evaluation of the species and content of H in a series of gem-quality orthogonal, monoclinic and triclinic crystals, including olivine, orthopyroxene, clinopyroxene, orthoclase and albite (natural and H-annealed). The results demonstrate that the sum of the integrated absorbance from two polarized spectra along two perpendicular directions in any given plane is a constant, and that the sum of the integrated absorbance from three polarized spectra along any three orthogonal directions is of essentially the same accuracy as that along the principal axes. It is also shown that this method works well, with a relative accuracy within 10%, even at some extreme cases where the sample absorption bands are both intense and strongly anisotropic.

On the complex relationship between energy expenditure and longevity: Reconciling the contradictory empirical results with a simple theoretical model.

PubMed

Hou, Chen; Amunugama, Kaushalya

2015-07-01

The relationship between energy expenditure and longevity has been a central theme in aging studies. Empirical studies have yielded controversial results, which cannot be reconciled by existing theories. In this paper, we present a simple theoretical model based on first principles of energy conservation and allometric scaling laws. The model takes into considerations the energy tradeoffs between life history traits and the efficiency of the energy utilization, and offers quantitative and qualitative explanations for a set of seemingly contradictory empirical results. We show that oxidative metabolism can affect cellular damage and longevity in different ways in animals with different life histories and under different experimental conditions. Qualitative data and the linearity between energy expenditure, cellular damage, and lifespan assumed in previous studies are not sufficient to understand the complexity of the relationships. Our model provides a theoretical framework for quantitative analyses and predictions. The model is supported by a variety of empirical studies, including studies on the cellular damage profile during ontogeny; the intra- and inter-specific correlations between body mass, metabolic rate, and lifespan; and the effects on lifespan of (1) diet restriction and genetic modification of growth hormone, (2) the cold and exercise stresses, and (3) manipulations of antioxidant. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Pure shear and simple shear calcite textures. Comparison of experimental, theoretical and natural data

USGS Publications Warehouse

Wenk, H.-R.; Takeshita, T.; Bechler, E.; Erskine, B.G.; Matthies, S.

1987-01-01

The pattern of lattice preferred orientation (texture) in deformed rocks is an expression of the strain path and the acting deformation mechanisms. A first indication about the strain path is given by the symmetry of pole figures: coaxial deformation produces orthorhombic pole figures, while non-coaxial deformation yields monoclinic or triclinic pole figures. More quantitative information about the strain history can be obtained by comparing natural textures with experimental ones and with theoretical models. For this comparison, a representation in the sensitive three-dimensional orientation distribution space is extremely important and efforts are made to explain this concept. We have been investigating differences between pure shear and simple shear deformation incarbonate rocks and have found considerable agreement between textures produced in plane strain experiments and predictions based on the Taylor model. We were able to simulate the observed changes with strain history (coaxial vs non-coaxial) and the profound texture transition which occurs with increasing temperature. Two natural calcite textures were then selected which we interpreted by comparing them with the experimental and theoretical results. A marble from the Santa Rosa mylonite zone in southern California displays orthorhombic pole figures with patterns consistent with low temperature deformation in pure shear. A limestone from the Tanque Verde detachment fault in Arizona has a monoclinic fabric from which we can interpret that 60% of the deformation occurred by simple shear. ?? 1987.

Adsorption geometry and core excitation spectra of three phenylpropene isomers on Cu(111)

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

Kolczewski, C.; Williams, F. J.; Cropley, R. L.

Theoretical C 1s near edge x-ray absorption fine structure (NEXAFS) spectra for the C{sub 9}H{sub 10} isomers trans-methylstyrene, {alpha}-methylstyrene, and allylbenzene in gas phase and adsorbed at Cu(111) surfaces have been obtained from density functional theory calculations where adsorbate geometries were determined by corresponding total energy optimizations. The three species show characteristic differences in widths and peak shapes of the lowest C 1s{yields}{pi}* transitions which are explained by different coupling of the {pi}-electron system of the C{sub 6} ring with that of the side chain in the molecules as well as by the existence of nonequivalent carbon centers. The adsorbedmore » molecules bind only weakly with the substrate which makes the use of theoretical NEXAFS spectra of the oriented free molecules meaningful for an interpretation of experimental angle-resolved NEXAFS spectra of the adsorbate systems obtained in this work. However, a detailed quantitative account of relative peak intensities requires theoretical angle-resolved NEXAFS spectra of the complete adsorbate systems which have been evaluated within the surface cluster approach. The comparison with experiment yields almost perfect agreement and confirms the reliability of the calculated equilibrium geometries of the adsorbates. This can help to explain observed differences in the catalytic epoxidation of the three molecules on Cu(111) based on purely geometric considerations.« less

Sociological and Communication-Theoretical Perspectives on the Commercialization of the Sciences

ERIC Educational Resources Information Center

Leydesdorff, Loet

2013-01-01

Both self-organization and organization are important for the further development of the sciences: the two dynamics condition and enable each other. Commercial and public considerations can interact and "interpenetrate" in historical organization; different codes of communication are then "recombined". However,…

A method to enhance the performance of synthetic origin-destination (O-D) trip table estimation models.

DOT National Transportation Integrated Search

1998-01-01

The conventional methods of determining origin-destination (O-D) trip tables involve elaborate surveys, e.g., home interviews, that require considerable time, staff, and funds. To overcome this drawback, a number of theoretical models that synthesize...

The Case Study Approach: Some Theoretical, Methodological and Applied Considerations

DTIC Science & Technology

2013-06-01

For example, a variety of programs/software are available such as: NUDIST , ATLAS/ti, HyperRESEARCH, AQUAD etc (Kelle 1997; Barry 1998... Nudist compared." Sociological Research Online 3(3). Baruch, Y. & Labert, R. (2007). "Organizational anxiety: Applying psychological concepts into

Mathematical Interaction Shaped by Communication, Epistemological Constraints and Enactivism

ERIC Educational Resources Information Center

Steinbring, Heinz

2015-01-01

On the surface, mathematical interaction often appears as an immediately transparent event that could be directly understood by careful observation. Theoretical considerations, however, clearly show that mathematical speaking and conversation in teaching-learning situations are highly complex social structures comprising many preconditions.…

Communication: Concepts and Processes.

ERIC Educational Resources Information Center

DeVito, Joseph A.

A mixture of theoretical and practical essays points up the purposes of, barriers to, and means of facilitating communication. Four models of how people communicate are presented. A series of essays describing communication messages and channels include considerations of "gobbledygook," nonverbal communication by touch, smell, or body movement,…

Safety of High Ground Transportation Systems - Human Factors Phase I: Function Analyses and Theoretical Considerations

DOT National Transportation Integrated Search

1994-10-01

Although the speed of guided ground transportation continues to increase, the reaction : time as well as the sensory and information processing capacities of on- and off-board : operators remain constant. This report, the first of two examining criti...

Operant Variability: Procedures and Processes

ERIC Educational Resources Information Center

Machado, Armando; Tonneau, Francois

2012-01-01

Barba's (2012) article deftly weaves three main themes in one argument about operant variability. From general theoretical considerations on operant behavior (Catania, 1973), Barba derives methodological guidelines about response differentiation and applies them to the study of operant variability. In the process, he uncovers unnoticed features of…

Strategic Issues in Quality Management: 1. Theoretical Considerations.

ERIC Educational Resources Information Center

Johannsen, Carl Gustav

1996-01-01

Examines the relationship between strategic management and quality management concepts in a library and information services setting. Conceptual frameworks are presented and a new strategic quality management framework, inspired by the Japanese policy deployment approach, is developed that also discusses total quality management. (Author/LRW)

Escaping the Tyranny of Belief

ERIC Educational Resources Information Center

Wiswell, Albert K.; Wells, C. Leanne

2004-01-01

This study describes an action research case study through which the dynamics of identifying and changing strongly held assumptions illustrate the differences between experiences that serve to strengthen beliefs from those that lead to learning. Theoretical considerations are presented linking cognitive schema, action science, attribution theory,…

Perspectives in Individualized Learning.

ERIC Educational Resources Information Center

Weisgerber, Robert A.

The readings presented here are an analysis of selected factors underlying the process of individualized learning. The book is organized topically and moves from theoretical considerations toward an analysis of important educational components. The readings come from a cross section of experts representing the areas of learning theory, individual…

Curricular Transposition in Citizenship Education

ERIC Educational Resources Information Center

McCowan, Tristan

2008-01-01

The considerable debate in recent years on the aims of citizenship education has not been accompanied by an equally substantial discussion on the educational processes involved. This article puts forward a theoretical framework, referred to as "curricular transposition", for understanding the complex task of realizing normative ideals of…

Theory of winds in late-type evolved and pre-main-sequence stars

NASA Technical Reports Server (NTRS)

Macgregor, K. B.

1983-01-01

Recent observational results confirm that many of the physical processes which are known to occur in the Sun also occur among late-type stars in general. One such process is the continuous loss of mass from a star in the form of a wind. There now exists an abundance of either direct or circumstantial evidence which suggests that most (if not all) stars in the cool portion of the HR diagram possess winds. An attempt is made to assess the current state of theoretical understanding of mass loss from two distinctly different classes of late-type stars: the post-main-sequence giant/supergiant stars and the pre-main-sequence T Tauri stars. Toward this end, the observationally inferred properties of the wind associated with each of the two stellar classes under consideration are summarized and compared against the predictions of existing theoretical models. Although considerable progress has been made in attempting to identify the mechanisms responsible for mass loss from cool stars, many fundamental problems remain to be solved.

Combined use of transcranial magnetic stimulation and metal electrode implants: a theoretical assessment of safety considerations

NASA Astrophysics Data System (ADS)

Golestanirad, Laleh; Rouhani, Hossein; Elahi, Behzad; Shahim, Kamal; Chen, Robert; Mosig, Juan R.; Pollo, Claudio; Graham, Simon J.

2012-12-01

This paper provides a theoretical assessment of the safety considerations encountered in the simultaneous use of transcranial magnetic stimulation (TMS) and neurological interventions involving implanted metallic electrodes, such as electrocorticography. Metal implants are subject to magnetic forces due to fast alternating magnetic fields produced by the TMS coil. The question of whether the mechanical movement of the implants leads to irreversible damage of brain tissue is addressed by an electromagnetic simulation which quantifies the magnitude of imposed magnetic forces. The assessment is followed by a careful mechanical analysis determining the maximum tolerable force which does not cause irreversible tissue damage. Results of this investigation provide useful information on the range of TMS stimulator output powers which can be safely used in patients having metallic implants. It is shown that conventional TMS applications can be considered safe when applied on patients with typical electrode implants as the induced stress in the brain tissue remains well below the limit of tissue damage.

Communicating about ocean health: theoretical and practical considerations

PubMed Central

McComas, Katherine A.; Byrne, Sahara E.

2016-01-01

As anthropogenic stressors threaten the health of marine ecosystems, there is a need to better understand how the public processes and responds to information about ocean health. Recent studies of public perceptions about ocean issues report high concern but limited knowledge, prompting calls for information campaigns to mobilize public support for ocean restoration policy. Drawing on the literature from communication, psychology and related social science disciplines, we consider a set of social-cognitive challenges that researchers and advocates are likely to encounter when communicating with the public about ocean health and emerging marine diseases—namely, the psychological distance at which ocean issues are construed, the unfamiliarity of aquatic systems to many members of the public and the potential for marine health issues to be interpreted through politicized schemas that encourage motivated reasoning over the dispassionate consideration of scientific evidence. We offer theory-based strategies to help public outreach efforts address these challenges and present data from a recent experiment exploring the role of message framing (emphasizing the public health or environmental consequences of marine disease) in shaping public support for environmental policy. PMID:26880833

Wavelength dependence of nanosecond infrared laser-induced breakdown in water: Evidence for multiphoton initiation via an intermediate state

NASA Astrophysics Data System (ADS)

Linz, Norbert; Freidank, Sebastian; Liang, Xiao-Xuan; Vogelmann, Hannes; Trickl, Thomas; Vogel, Alfred

2015-04-01

Investigation of the wavelength dependence (725-1025 nm) of the threshold for nanosecond optical breakdown in water revealed steps consistent with breakdown initiation by multiphoton ionization, with an initiation energy of about 6.6 eV. This value is considerably smaller than the autoionization threshold of about 9.5 eV, which can be regarded as band gap relevant for avalanche ionization. Breakdown initiation is likely to occur via excitation of a valence band electron into a solvated state, followed by rapid excitation into the conduction band. Theoretical analysis based on these assumptions suggests that the seed electron density required for initiating avalanche ionization amounts to 2.5 ×1015c m-3 at 725 nm and drops to 1.1 ×1012c m-3 at 1025 nm. These results demand changes of future breakdown modeling for water, including the use of a larger band gap than previously employed, the introduction of an intermediate energy level for initiation, and consideration of the wavelength dependence of seed electron density.

Nondestructive Evaluation of One-Dimensional Periodic Structures by Transmission of Laser-Excited Wide-Band Acoustic Pulses

NASA Astrophysics Data System (ADS)

Karabutov, A. A.; Kozhushko, V. V.; Pelivanov, I. M.; Podymova, N. B.

2001-03-01

The propagation of ultrasound in a one-dimensional model and actual periodic structures (PSs) is studied experimentally by the method of optoacoustic spectroscopy based on the laser thermooptical excitation and wide-band piezodetection of short acoustic pulses. It is shown that the ultrasound transmission spectrum of a PS has stop and pass bands, and the greater the number of layers in the PSs, the deeper the stop bands. The case where the thickness, density, and ultrasound velocity of one or several layers in the PS are modified is studied in detail. In this case, a narrow local maximum of ultrasound transmission appears in the stop band, whose location depends considerably on the position of the "defective" layer in the PS. The experimental data obtained coincide well with the theoretical calculation. The nondestructive evaluation of actual PSs consisting of two epoxy-glued identical aluminum plates is carried out by the optoacoustic method. Such materials are widely used in aircraft industry. It is shown that the ultrasound transmission spectrum for these materials depends considerably on the thickness of the epoxy-glue layer.

A Novel High-Sensitivity, Low-Power, Liquid Crystal Temperature Sensor

PubMed Central

Algorri, José Francisco; Urruchi, Virginia; Bennis, Noureddine; Sánchez-Pena, José Manuel

2014-01-01

A novel temperature sensor based on nematic liquid crystal permittivity as a sensing magnitude, is presented. This sensor consists of a specific micrometric structure that gives considerable advantages from other previous related liquid crystal (LC) sensors. The analytical study reveals that permittivity change with temperature is introduced in a hyperbolic cosine function, increasing the sensitivity term considerably. The experimental data has been obtained for ranges from −6 °C to 100 °C. Despite this, following the LC datasheet, theoretical ranges from −40 °C to 109 °C could be achieved. These results have revealed maximum sensitivities of 33 mVrms/°C for certain temperature ranges; three times more than of most silicon temperature sensors. As it was predicted by the analytical study, the micrometric size of the proposed structure produces a high output voltage. Moreover the voltage's sensitivity to temperature response can be controlled by the applied voltage. This response allows temperature measurements to be carried out without any amplification or conditioning circuitry, with very low power consumption. PMID:24721771

Sound propagation in street canyons: comparison between diffusely and geometrically reflecting boundaries

PubMed

Kang

2000-03-01

This paper systematically compares the sound fields in street canyons with diffusely and geometrically reflecting boundaries. For diffuse boundaries, a radiosity-based theoretical/computer model has been developed. For geometrical boundaries, the image source method has been used. Computations using the models show that there are considerable differences between the sound fields resulting from the two kinds of boundaries. By replacing diffuse boundaries with geometrical boundaries, the sound attenuation along the length becomes significantly less; the RT30 is considerably longer; and the extra attenuation caused by air or vegetation absorption is reduced. There are also some similarities between the sound fields under the two boundary conditions. For example, in both cases the sound attenuation along the length with a given amount of absorption is the highest if the absorbers are arranged on one boundary and the lowest if they are evenly distributed on all boundaries. Overall, the results suggest that, from the viewpoint of urban noise reduction, it is better to design the street boundaries as diffusely reflective rather than acoustically smooth.

Communicating about ocean health: theoretical and practical considerations.

PubMed

Schuldt, Jonathon P; McComas, Katherine A; Byrne, Sahara E

2016-03-05

As anthropogenic stressors threaten the health of marine ecosystems, there is a need to better understand how the public processes and responds to information about ocean health. Recent studies of public perceptions about ocean issues report high concern but limited knowledge, prompting calls for information campaigns to mobilize public support for ocean restoration policy. Drawing on the literature from communication, psychology and related social science disciplines, we consider a set of social-cognitive challenges that researchers and advocates are likely to encounter when communicating with the public about ocean health and emerging marine diseases--namely, the psychological distance at which ocean issues are construed, the unfamiliarity of aquatic systems to many members of the public and the potential for marine health issues to be interpreted through politicized schemas that encourage motivated reasoning over the dispassionate consideration of scientific evidence. We offer theory-based strategies to help public outreach efforts address these challenges and present data from a recent experiment exploring the role of message framing (emphasizing the public health or environmental consequences of marine disease) in shaping public support for environmental policy. © 2016 The Author(s).

Theoretical Study of α-V2O5 -Based Double-Wall Nanotubes.

PubMed

Porsev, Vitaly V; Bandura, Andrei V; Evarestov, Robert A

2015-10-05

First-principles calculations of the atomic and electronic structure of double-wall nanotubes (DWNTs) of α-V2 O5 are performed. Relaxation of the DWNT structure leads to the formation of two types of local regions: 1) bulk-type regions and 2) puckering regions. Calculated total density of states (DOS) of DWNTs considerably differ from that of single-wall nanotubes and the single layer, as well as from the DOS of the bulk and double layer. Small shoulders that appear on edges of valence and conduction bands result in a considerable decrease in the band gaps of the DWNTs (up to 1 eV relative to the single-layer gaps). The main reason for this effect is the shift of the inner- and outer-wall DOS in opposite directions on the energetic scale. The electron density corresponding to shoulders at the conduction-band edges is localized on vanadium atoms of the bulk-type regions, whereas the electron density corresponding to shoulders at the valence-band edges belongs to oxygen atoms of both regions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Experimental study of the constituents of space wash water

NASA Technical Reports Server (NTRS)

Putnam, D. F.; Colombo, G. V.

1975-01-01

This report presents experimental data, obtained under controlled conditions, which quantify the various constituents of human origin that may be expected in space wash water. The experiments were conducted with a simulated crew of two male and two female subjects. The data show that the expected wash water contaminants originating from human secretions are substantially lower than theoretical projections indicated. The data presented are immediately useful and may have considerable impact on the tradeoff comparisons among various unit processes and systems under consideration by NASA for recycling space wash water.

Methods of satellite oceanography

NASA Technical Reports Server (NTRS)

Stewart, R. H.

1985-01-01

The theoretical basis for remote sensing measurements of climate and ocean dynamics is examined. Consideration is given to: the absorption of electromagnetic radiation in the atmosphere; scattering in the atmosphere; and satellite observations using visible light. Consideration is also given to: the theory of radio scatter from the sea; scatter of centimeter waves from the sea; and the theory of operation of synthetic aperture radars. Additional topics include: the coordinate systems of satellite orbits for oceanographic remote sensing applications; the operating features of the major U.S. satellite systems for viewing the ocean; and satellite altimetry.

Interleaved concatenated codes: New perspectives on approaching the Shannon limit

PubMed Central

Viterbi, A. J.; Viterbi, A. M.; Sindhushayana, N. T.

1997-01-01

The last few years have witnessed a significant decrease in the gap between the Shannon channel capacity limit and what is practically achievable. Progress has resulted from novel extensions of previously known coding techniques involving interleaved concatenated codes. A considerable body of simulation results is now available, supported by an important but limited theoretical basis. This paper presents a computational technique which further ties simulation results to the known theory and reveals a considerable reduction in the complexity required to approach the Shannon limit. PMID:11038568

[Consideration of hemodynamics in the intervillous space of the placenta (author's transl)].

PubMed

Heilmann, L; Mattheck, C; Wiemer, W

1977-06-01

Using Freese's hemodynamic model, we calculated the speed and pressure distribution in the villi-free area of the cotyledon. The Navier-Stokes equation was converted approximately into Reynod factors. The villi-free area was described as circular diffusor. On the basis of our computations, we assume that a predominately laminar flow occurred in the intervillous space; we considered an angular apearature of between 10 and 40 degrees to be physiological. In this area, pressure distribution is homogenous. The model-theoretical considerations presented here substantiate Freese's conception.

Labyrinthine flows across multilayer graphene-based membranes

NASA Astrophysics Data System (ADS)

Yoshida, Hiroaki

Graphene-based materials have recently found extremely wide applications for fluidic purposes thanks to remarkable developments in micro-/nano-fabrication techniques. In particular, high permeability and specific selectivity have been reported for these graphene-based membranes, such as the graphene-oxide membranes, with however controversial experimental results. There is therefore an urgent need to propose a theoretical framework of fluid transport in these architectures in order to rationalize the experimental results.In this presentation, we report a theoretical study of mass transport across multilayer graphene based membranes, which we benchmark by atomic-scale molecular dynamics. Specifically, we consider the water flow across multiple graphene layers with an inter-layer distance ranging from sub-nanometer to a few nanometers. The graphene layers have nanoslits aligned in a staggered fashion, and thus the water flows involve multiple twists and turns. We compare the continuum model predictions for the permeability with the lattice Boltzmann calculations and molecular dynamics simulations. The highlight is that, in spite of extreme confinement, the permeability across the graphene-based membrane is quantitatively predicted on the basis of a properly designed continuum model. The framework of this study constitutes a benchmark to which we compare favourably published experimental data.In addition, flow properties of a water-ethanol mixture are presented, demonstrating the possibility of a novel separation technique. While the membrane is permeable to both pure liquids, it exhibits a counter-intuitive ``self-semi-permeability'' to water in the presence of the mixture. This suggests a robust and versatile membrane-based separation method built on a pressure-driven reverse-osmosis process, which is considerably less energy consuming than distillation processes. The author acknowledges the ERC project Micromegas and the ANR projects BlueEnergy and Equip@Meso.

Few-mode fiber based Raman distributed temperature sensing.

PubMed

Wang, Meng; Wu, Hao; Tang, Ming; Zhao, Zhiyong; Dang, Yunli; Zhao, Can; Liao, Ruolin; Chen, Wen; Fu, Songnian; Yang, Chen; Tong, Weijun; Shum, Perry Ping; Liu, Deming

2017-03-06

We proposed and experimentally demonstrated a few mode fiber (FMF) based Raman distributed temperature sensor (RDTS) to extend the sensing distance with enhanced signal-to-noise ratio (SNR) of backscattered anti-Stokes spontaneous Raman scattering. Operating in the quasi-single mode (QSM) with efficient fundamental mode excitement, the FMF allows much larger input pump power before the onset of stimulated Raman scattering compared with the standard single mode fiber (SSMF) and mitigates the detrimental differential mode group delay (DMGD) existing in the conventional multimode fiber (MMF) based RDTS system. Comprehensive theoretical analysis has been conducted to reveal the benefits of RDTS brought by QSM operated FMFs with the consideration of geometric/optical parameters of different FMFs. The measurement uncertainty of FMF based scheme has also been evaluated. Among fibers being investigated and compared (SSMF, 2-mode and 4-mode FMFs, respectively), although an ideal 4-mode FMF based RDTS has the largest SNR enhancement in principle, real fabrication imperfections and larger splicing loss degrade its performance. While the 2-mode FMF based system outperforms in longer distance measurement, which agrees well with the theoretical calculations considering real experimental parameters. Using the conventional RDTS hardware, a 30-ns single pulse at 1550nm has been injected as the pump; the obtained temperature resolutions at 20km distance are estimated to be about 10°C, 7°C and 6°C for the SSMF, 4-mode and 2-mode FMFs, respectively. About 4°C improvement over SSMF on temperature resolution at the fiber end with 3m spatial resolution within 80s measuring time over 20km 2-mode FMFs have been achieved.

DNA Sequence-Dependent Ionic Currents in Ultra-Small Solid-State Nanopores†

PubMed Central

Comer, Jeffrey

2016-01-01

Measurements of ionic currents through nanopores partially blocked by DNA have emerged as a powerful method for characterization of the DNA nucleotide sequence. Although the effect of the nucleotide sequence on the nanopore blockade current has been experimentally demonstrated, prediction and interpretation of such measurements remain a formidable challenge. Using atomic resolution computational approaches, here we show how the sequence, molecular conformation, and pore geometry affect the blockade ionic current in model solid-state nanopores. We demonstrate that the blockade current from a DNA molecule is determined by the chemical identities and conformations of at least three consecutive nucleotides. We find the blockade currents produced by the nucleotide triplets to vary considerably with their nucleotide sequence despite having nearly identical molecular conformations. Encouragingly, we find blockade current differences as large as 25% for single-base substitutions in ultra small (1.6 nm × 1.1 nm cross section; 2 nm length) solid-state nanopores. Despite the complex dependence of the blockade current on the sequence and conformation of the DNA triplets, we find that, under many conditions, the number of thymine bases is positively correlated with the current, whereas the number of purine bases and the presence of both purine and pyrimidines in the triplet are negatively correlated with the current. Based on these observations, we construct a simple theoretical model that relates the ion current to the base content of a solid-state nanopore. Furthermore, we show that compact conformations of DNA in narrow pores provide the greatest signal-to-noise ratio for single base detection, whereas reduction of the nanopore length increases the ionic current noise. Thus, the sequence dependence of nanopore blockade current can be theoretically rationalized, although the predictions will likely need to be customized for each nanopore type. PMID:27103233

A guide to using the Theoretical Domains Framework of behaviour change to investigate implementation problems.

PubMed

Atkins, Lou; Francis, Jill; Islam, Rafat; O'Connor, Denise; Patey, Andrea; Ivers, Noah; Foy, Robbie; Duncan, Eilidh M; Colquhoun, Heather; Grimshaw, Jeremy M; Lawton, Rebecca; Michie, Susan

2017-06-21

Implementing new practices requires changes in the behaviour of relevant actors, and this is facilitated by understanding of the determinants of current and desired behaviours. The Theoretical Domains Framework (TDF) was developed by a collaboration of behavioural scientists and implementation researchers who identified theories relevant to implementation and grouped constructs from these theories into domains. The collaboration aimed to provide a comprehensive, theory-informed approach to identify determinants of behaviour. The first version was published in 2005, and a subsequent version following a validation exercise was published in 2012. This guide offers practical guidance for those who wish to apply the TDF to assess implementation problems and support intervention design. It presents a brief rationale for using a theoretical approach to investigate and address implementation problems, summarises the TDF and its development, and describes how to apply the TDF to achieve implementation objectives. Examples from the implementation research literature are presented to illustrate relevant methods and practical considerations. Researchers from Canada, the UK and Australia attended a 3-day meeting in December 2012 to build an international collaboration among researchers and decision-makers interested in the advancing use of the TDF. The participants were experienced in using the TDF to assess implementation problems, design interventions, and/or understand change processes. This guide is an output of the meeting and also draws on the authors' collective experience. Examples from the implementation research literature judged by authors to be representative of specific applications of the TDF are included in this guide. We explain and illustrate methods, with a focus on qualitative approaches, for selecting and specifying target behaviours key to implementation, selecting the study design, deciding the sampling strategy, developing study materials, collecting and analysing data, and reporting findings of TDF-based studies. Areas for development include methods for triangulating data, e.g. from interviews, questionnaires and observation and methods for designing interventions based on TDF-based problem analysis. We offer this guide to the implementation community to assist in the application of the TDF to achieve implementation objectives. Benefits of using the TDF include the provision of a theoretical basis for implementation studies, good coverage of potential reasons for slow diffusion of evidence into practice and a method for progressing from theory-based investigation to intervention.

Finding order in complexity: themes from the career of Dr. Robert F. Wagner

NASA Astrophysics Data System (ADS)

Myers, Kyle J.

2009-02-01

Over the course of his long and productive career, Dr. Robert F. Wagner built a framework for the evaluation of imaging systems based on a task-based, decision theoretic approach. His most recent contributions involved the consideration of the random effects associated with multiple readers of medical images and the logical extension of this work to the problem of the evaluation of multiple competing classifiers in statistical pattern recognition. This contemporary work expanded on familiar themes from Bob's many SPIE presentations in earlier years. It was driven by the need for practical solutions to current problems facing FDA'S Center for Devices and Radiological Health and the medical imaging community regarding the assessment of new computer-aided diagnosis tools and Bob's unique ability to unify concepts across a range of disciplines as he gave order to increasingly complex problems in our field.

Genesis and shape of natural solution cavities within salt deposits

NASA Astrophysics Data System (ADS)

Gechter, Daniel; Huggenberger, Peter; Ackerer, Philippe; Waber, H. Niklaus

2008-11-01

Since the genesis and shape of natural deep-seated cavities within a salt body are insufficiently understood, the current study tries to shed some light on this topic. To this end, freshwater was pumped slowly through a horizontal borehole in rock salt cores. Owing to fast halite dissolution kinetics, high solubility, and slow inflow rate, halite dissolution took place only in the inflow of the rock salt cylinder. The shape of the created cavities is an approximately symmetrical half cone with a horizontal base facing upward. A conceptual model is presented that is inspired by the experimental results and based on theoretical hydraulic-geochemical considerations, as well as on field observations. It proposes that triangular prism or conically shaped cavities develop within salt under confined conditions, where aggressive water flows upward along a fracture/conduit from an insoluble aquifer into the soluble stratum. Such cavity enlargements may cause land subsidence and structure collapse.

Tunneled Mesoporous Carbon Nanofibers with Embedded ZnO Nanoparticles for Ultrafast Lithium Storage.

PubMed

An, Geon-Hyoung; Lee, Do-Young; Ahn, Hyo-Jin

2017-04-12

Carbon and metal oxide composites have received considerable attention as anode materials for Li-ion batteries (LIBs) owing to their excellent cycling stability and high specific capacity based on the chemical and physical stability of carbon and the high theoretical specific capacity of metal oxides. However, efforts to obtain ultrafast cycling stability in carbon and metal oxide composites at high current density for practical applications still face important challenges because of the longer Li-ion diffusion pathway, which leads to poor ultrafast performance during cycling. Here, tunneled mesoporous carbon nanofibers with embedded ZnO nanoparticles (TMCNF/ZnO) are synthesized by electrospinning, carbonization, and postcalcination. The optimized TMCNF/ZnO shows improved electrochemical performance, delivering outstanding ultrafast cycling stability, indicating a higher specific capacity than previously reported ZnO-based anode materials in LIBs. Therefore, the unique architecture of TMCNF/ZnO has potential for use as an anode material in ultrafast LIBs.

Redundancy and reduction: Speakers manage syntactic information density

PubMed Central

Florian Jaeger, T.

2010-01-01

A principle of efficient language production based on information theoretic considerations is proposed: Uniform Information Density predicts that language production is affected by a preference to distribute information uniformly across the linguistic signal. This prediction is tested against data from syntactic reduction. A single multilevel logit model analysis of naturally distributed data from a corpus of spontaneous speech is used to assess the effect of information density on complementizer that-mentioning, while simultaneously evaluating the predictions of several influential alternative accounts: availability, ambiguity avoidance, and dependency processing accounts. Information density emerges as an important predictor of speakers’ preferences during production. As information is defined in terms of probabilities, it follows that production is probability-sensitive, in that speakers’ preferences are affected by the contextual probability of syntactic structures. The merits of a corpus-based approach to the study of language production are discussed as well. PMID:20434141

Design Principles for Fragment Libraries: Maximizing the Value of Learnings from Pharma Fragment-Based Drug Discovery (FBDD) Programs for Use in Academia.

PubMed

Keserű, György M; Erlanson, Daniel A; Ferenczy, György G; Hann, Michael M; Murray, Christopher W; Pickett, Stephen D

2016-09-22

Fragment-based drug discovery (FBDD) is well suited for discovering both drug leads and chemical probes of protein function; it can cover broad swaths of chemical space and allows the use of creative chemistry. FBDD is widely implemented for lead discovery in industry but is sometimes used less systematically in academia. Design principles and implementation approaches for fragment libraries are continually evolving, and the lack of up-to-date guidance may prevent more effective application of FBDD in academia. This Perspective explores many of the theoretical, practical, and strategic considerations that occur within FBDD programs, including the optimal size, complexity, physicochemical profile, and shape profile of fragments in FBDD libraries, as well as compound storage, evaluation, and screening technologies. This compilation of industry experience in FBDD will hopefully be useful for those pursuing FBDD in academia.

[Some considerations about aesthetic medicine].

PubMed

Ferreira, Francisco Romão

2010-01-01

In this article, we will discuss some aspects of the construction of the meanings concerning the body from the scientific speech which was modeled based on modern thinking and became the hegemonic thinking of some sectors of the medical field. Meanings attributed to the body bring questions that come from other areas of the social life and those questions will build the aesthetic parameters which will be part of the identity construction, in the relation with the body itself, subjectivity and healthcare. We will describe some moments of the construction of the modern scientific thought and how this thought became hegemonic, influences the common sense, naturalizes identity construction and how dealing with the body, interferes in the healthcare, show a division among some sectors of the biomedicine, reinforce an specific type of medical rationality and makes an epistemic base and principle (theoretical and discursive) to some sectors connected to aesthetic medicine and aesthetic surgeries.

Kinetics of a gas adsorption compressor

NASA Technical Reports Server (NTRS)

Chan, C. K.; Tward, E.; Elleman, D. D.

1984-01-01

Chan (1981) has suggested that a process based on gas adsorption could be used as a means to drive a Joule-Thomson (J-T) device. The resulting system has several advantages. It is heat powered, it has no sealing, there are no mechanical moving parts, and no active control is required. In the present investigation, a two-phase model is used to analyze the transients of a gas adsorption compressor. The modeling of the adsorption process is based on a consideration of complete thermal and mechanical equilibrium between the gaseous phase and the adsorbed gas phase. The experimental arrangement for two sets of kinetic tests is discussed, and data regarding the experimental results are presented in graphs. For a theoretical study, a two-phase model was developed to predict the transient behavior of the compressor. A computer code was written to solve the governing equations with the aid of a standard forward marching predictor-corrector method.

Measurement and fitting techniques for the assessment of material nonlinearity using nonlinear Rayleigh waves

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

Torello, David; Kim, Jin-Yeon; Qu, Jianmin

2015-03-31

This research considers the effects of diffraction, attenuation, and the nonlinearity of generating sources on measurements of nonlinear ultrasonic Rayleigh wave propagation. A new theoretical framework for correcting measurements made with air-coupled and contact piezoelectric receivers for the aforementioned effects is provided based on analytical models and experimental considerations. A method for extracting the nonlinearity parameter β{sub 11} is proposed based on a nonlinear least squares curve-fitting algorithm that is tailored for Rayleigh wave measurements. Quantitative experiments are conducted to confirm the predictions for the nonlinearity of the piezoelectric source and to demonstrate the effectiveness of the curve-fitting procedure. Thesemore » experiments are conducted on aluminum 2024 and 7075 specimens and a β{sub 11}{sup 7075}/β{sub 11}{sup 2024} measure of 1.363 agrees well with previous literature and earlier work.« less

Design of a Single Motor Based Leg Structure with the Consideration of Inherent Mechanical Stability

NASA Astrophysics Data System (ADS)

Taha Manzoor, Muhammad; Sohail, Umer; Noor-e-Mustafa; Nizami, Muhammad Hamza Asif; Ayaz, Yasar

2017-07-01

The fundamental aspect of designing a legged robot is constructing a leg design that is robust and presents a simple control problem. In this paper, we have successfully designed a robotic leg based on a unique four bar mechanism with only one motor per leg. The leg design parameters used in our platform are extracted from design principles used in biological systems, multiple iterations and previous research findings. These principles guide a robotic leg to have minimal mechanical passive impedance, low leg mass and inertia, a suitable foot trajectory utilizing a practical balance between leg kinematics and robot usage, and the resultant inherent mechanical stability. The designed platform also exhibits the key feature of self-locking. Theoretical tools and software iterations were used to derive these practical features and yield an intuitive sense of the required leg design parameters.

Practical Strategies for Collaboration across Discipline-Based Education Research and the Learning Sciences

PubMed Central

Peffer, Melanie; Renken, Maggie

2016-01-01

Rather than pursue questions related to learning in biology from separate camps, recent calls highlight the necessity of interdisciplinary research agendas. Interdisciplinary collaborations allow for a complicated and expanded approach to questions about learning within specific science domains, such as biology. Despite its benefits, interdisciplinary work inevitably involves challenges. Some such challenges originate from differences in theoretical and methodological approaches across lines of work. Thus, aims at developing successful interdisciplinary research programs raise important considerations regarding methodologies for studying biology learning, strategies for approaching collaborations, and training of early-career scientists. Our goal here is to describe two fields important to understanding learning in biology, discipline-based education research and the learning sciences. We discuss differences between each discipline’s approach to biology education research and the benefits and challenges associated with incorporating these perspectives in a single research program. We then propose strategies for building productive interdisciplinary collaboration. PMID:27881446

Going Global: Toward Competency-Based Best Practices for Global Health in Dental Education.

PubMed

Seymour, Brittany; Shick, Elizabeth; Chaffee, Benjamin W; Benzian, Habib

2017-06-01

The Global Oral Health Interest Group of the Consortium of Universities for Global Health (GOHIG-CUGH) published recommended competencies to support development of competency-based global health education in dental schools. However, there has been no comprehensive, systematically derived, or broadly accepted framework for creating and delivering competency-based global health education to dental students. This article describes the results of a collaborative workshop held at the 2016 American Dental Education Association (ADEA) Annual Session & Exhibition designed to build on the GOHIG-CUGH competencies and start to develop systematic approaches for their practical application. Workshop organizers developed a preliminary theoretical framework for guiding the development of global health in dental education, grounded in published research. Collectively, workshop participants developed detailed outcomes for the theoretical framework with a focus on three educational practices: didactic, experiential, and research learning and how each can meet the competencies. Participants discussed learning objectives, keys to implementation, ethical considerations, challenges, and examples of success. Outcomes demonstrated that no educational practice on its own meets all 33 recommended competencies for dental students; however, the three educational practices combined may potentially cover all 33. Participants emphasized the significance of sustainable approaches to student learning for both students and communities, with identified partners in the communities to collaborate on the development, implementation, evaluation, and long-term maintenance of any student global health activity. These findings may represent early steps toward professional consensus and best practices for global health in dental education in the United States.