A Composite Theoretical Model Showing Potential Hidden Costs of Online Distance Education at Historically Black Colleges and Universities: With Implications for Building Cost-Resistant Courses and Programs

ERIC Educational Resources Information Center

Arroyo, Andrew T.

2014-01-01

Growing numbers of historically Black colleges and universities (HBCUs) are entering the arena of online distance education. Some are seeking to grow large-scale programs that can compete for market share with historically White institutions and for-profit schools. This theoretical essay develops a composite model to assist HBCU administrators in…

Theoretical investigations on plasma processes in the Kaufman thruster. [electron and ion velocity distribution

NASA Technical Reports Server (NTRS)

Wilhelm, H. E.

1974-01-01

An analysis of the sputtering of metal surfaces and grids by ions of medium energies is given and it is shown that an exact, nonlinear, hyperbolic wave equation for the temperature field describes the transient transport of heat in metals. Quantum statistical and perturbation theoretical analysis of surface sputtering by low energy ions are used to develop the same expression for the sputtering rate. A transport model is formulated for the deposition of sputtered atoms on system components. Theoretical efforts in determining the potential distribution and the particle velocity distributions in low pressure discharges are briefly discussed.

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.

The Development of Education and Training Systems in the Field of Nanotechnology

ERIC Educational Resources Information Center

Poteralska, Beata; Zielinska, Joanna; Mazurkiewicz, Adam

2007-01-01

The paper presents the dynamic development of nanotechnologies in the world and--on this basis--the educational demand for scientists, engineers and didactic staff. Proposed and created forms of education and development related to nanotechnology in theoretical and practical aspect are shown as well. The potential and educational possibilities…

Models of consumer value cocreation in health care.

PubMed

Nambisan, Priya; Nambisan, Satish

2009-01-01

In recent years, consumer participation in health care has gained critical importance as health care organizations (HCOs) seek varied avenues to enhance the quality and the value of their offerings. Many large HCOs have established online health communities where health care consumers (patients) can interact with one another to share knowledge and offer emotional support in disease management and care. Importantly, the focus of consumer participation in health care has moved beyond such personal health care management as the potential for consumers to participate in innovation and value creation in varied areas of the health care industry becomes increasingly evident. Realizing such potential, however, will require HCOs to develop a better understanding of the varied types of consumer value cocreation that are enabled by new information and communication technologies such as online health communities and Web 2.0 (social media) technologies. This article seeks to contribute toward such an understanding by offering a concise and coherent theoretical framework to analyze consumer value cocreation in health care. We identify four alternate models of consumer value cocreation-the partnership model, the open-source model, the support-group model, and the diffusion model-and discuss their implications for HCOs. We develop our theoretical framework by drawing on theories and concepts in knowledge creation, innovation management, and online communities. A set of propositions are developed by combining theoretical insights from these areas with real-world examples of consumer value cocreation in health care. The theoretical framework offered here informs on the potential impact of the different models of consumer value cocreation on important organizational variables such as innovation cost and time, service quality, and consumer perceptions of HCO. An understanding of the four models of consumer value cocreation can help HCOs adopt appropriate strategies and practices to embrace consumers as partners in the development and delivery of innovative health care products and services.

The Learning Potential of Boundary Crossing in the Context of Product Introduction

ERIC Educational Resources Information Center

Gustavsson, Maria; Säfsten, Kristina

2017-01-01

The aim is to explore challenges related to the integration between product development and production in product introduction and, given these challenges, to analyse the learning potential of boundary crossing in the context of product introduction. The paper draws on evidence from a Swedish manufacturing company. The theoretical framework is…

Surface potential extraction from electrostatic and Kelvin-probe force microscopy images

NASA Astrophysics Data System (ADS)

Xu, Jie; Chen, Deyuan; Li, Wei; Xu, Jun

2018-05-01

A comprehensive comparison study of electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM) is conducted in this manuscript. First, it is theoretically demonstrated that for metallic or semiconductor samples, both the EFM and KPFM signals are a convolution of the sample surface potential with their respective transfer functions. Then, an equivalent point-mass model describing cantilever deflection under distributed loads is developed to reevaluate the cantilever influence on detection signals, and it is shown that the cantilever has no influence on the EFM signal, while it will affect the KPFM signal intensity but not change the resolution. Finally, EFM and KPFM experiments are carried out, and the surface potential is extracted from the EFM and KPFM images by deconvolution processing, respectively. The extracted potential intensity is well consistent with each other and the detection resolution also complies with the theoretical analysis. Our work is helpful to perform a quantitative analysis of EFM and KPFM signals, and the developed point-mass model can also be used for other cantilever beam deflection problems.

Effect of periodic potential on exciton states in semiconductor carbon nanotubes

DOE PAGES

Roslyak, Oleksiy; Piryatinski, Andrei

2016-05-28

Here we develop a theoretical background to treat exciton states in semiconductor single-walled carbon nanotubes (SWCNTs) in the presence of a periodic potential induced by a surface acoustic wave (SAW) propagating along SWCNT. The formalism accounts for the electronic band splitting into the Floquet subbands induced by the Bragg scattering on the SAW potential. Optical transitions between the Floquet states and correlated electron–hole pairs (excitons) are numerically examined. Formation of new van Hove singularities within the edges of Floquet sub-bands and associated transfer of the exciton oscillator strengths resulting in the photoluminescence quenching are predicted. The simulations demonstrate the excitonmore » energy red Stark shift and reduction in the exciton binding energy. We provide comparison of our results with reported theoretical and experimental studies.« less

Developing a Survey of Transformative Learning Outcomes and Processes Based on Theoretical Principles

ERIC Educational Resources Information Center

Stuckey, Heather L.; Taylor, Edward W.; Cranton, Patricia

2013-01-01

The purpose of this research was to develop an inclusive evaluation of "transformative learning theory" that encompassed varied perspectives of transformative learning. We constructed a validated quantitative survey to assess the potential outcomes and processes of how transformative learning may be experienced by college-educated…

Theoretical investigation of the structural stabilities, optoelectronic properties and thermodynamic characteristics of GaPxSb1-x ternary alloys

NASA Astrophysics Data System (ADS)

Oumelaz, F.; Nemiri, O.; Boumaza, A.; Ghemid, S.; Meradji, H.; Bin Omran, S.; El Haj Hassan, F.; Rai, D. P.; Khenata, R.

2018-06-01

In this theoretical study, we have investigated the structural, phase transition, electronic, thermodynamic and optical properties of GaPxSb1-x ternary alloys. Our calculations are performed with the WIEN2k code based on density functional theory using the full-potential linearized augmented plane wave method. For the electron exchange-correlation potential, a generalized gradient approximation within Wu-Cohen scheme is considered. The recently developed Tran-Blaha modified Becke-Johnson potential has also been used to improve the underestimated band gap. The structural properties, including the lattice constants, the bulk moduli and their pressure derivatives are in very good agreement with the available experimental data and theoretical results. Several structural phase transitions were studied here to establish the stable structure and to predict the phase transition under hydrostatic pressure. The computed transition pressure (Pt) of the material of our interest from the zinc blende (B3) to the rock salt (B1) phase has been determined and found to agree well with the experimental and theoretical data. The calculated band structure shows that GaSb binary compound and the ternary alloys are direct band gap semiconductors. Optical parameters such as the dielectric constants and the refractive indices are calculated and analyzed. The thermodynamic results are also interpreted and analyzed.

Education and Identity. Second Edition. The Jossey-Bass Higher and Adult Education Series.

ERIC Educational Resources Information Center

Chickering, Arthur W.; Reisser, Linda

Developing policies and practices to create higher education environments that will foster broad-based development of human talent and potentials is the focus of this fully revised and updated edition, which adds findings from the last 25 years to a classic work. The volume begins with "A Current Theoretical Context for Student Development," which…

A theoretical flaw in the advance market commitment idea.

PubMed

Sonderholm, Jorn

2010-06-01

Infectious and parasitic diseases cause massive health problems in the developing world. Research and development of drugs for diseases that mainly affect poor people in developing countries is limited. The advance market commitment (AMC) idea is an incentivising mechanism for research and development of drugs for neglected diseases. Discussion of the AMC idea is of renewed interest given the launch in June 2009 of the first AMC. This pilot AMC is designed to, among other things, test the idea for potential future applications. This paper is a critique of the AMC idea. It seeks to show that the idea has a hitherto unrecognised theoretical flaw that should make policy-makers and donors hesitant to embrace future applications of the idea.

Probabilistic, Decision-theoretic Disease Surveillance and Control

PubMed Central

Wagner, Michael; Tsui, Fuchiang; Cooper, Gregory; Espino, Jeremy U.; Harkema, Hendrik; Levander, John; Villamarin, Ricardo; Voorhees, Ronald; Millett, Nicholas; Keane, Christopher; Dey, Anind; Razdan, Manik; Hu, Yang; Tsai, Ming; Brown, Shawn; Lee, Bruce Y.; Gallagher, Anthony; Potter, Margaret

2011-01-01

The Pittsburgh Center of Excellence in Public Health Informatics has developed a probabilistic, decision-theoretic system for disease surveillance and control for use in Allegheny County, PA and later in Tarrant County, TX. This paper describes the software components of the system and its knowledge bases. The paper uses influenza surveillance to illustrate how the software components transform data collected by the healthcare system into population level analyses and decision analyses of potential outbreak-control measures. PMID:23569617

The lambda point experiment in microgravity

NASA Technical Reports Server (NTRS)

Lipa, J. A.

1988-01-01

The motivation and potential for performing very high resolution measurements of the heat capacity singularity at the lambda point of helium in microgravity conditions was briefly discussed. It is clear that tests extending deep into the asymptotic region can be performed, where the theoretical predictions take on their simplest form. This advantageous situation should lead to a major improvement in the understanding of the range of applicability of current theoretical ideas in this field. The lambda transition holds out the prospect of giving the maximum advance of any system, and with the application of cryogenic techniques, the potential of this system can be realized. The technology for the initial experiments is already developed, and results could be obtained in 1990.

Simple theoretical models for composite rotor blades

NASA Technical Reports Server (NTRS)

Valisetty, R. R.; Rehfield, L. W.

1984-01-01

The development of theoretical rotor blade structural models for designs based upon composite construction is discussed. Care was exercised to include a member of nonclassical effects that previous experience indicated would be potentially important to account for. A model, representative of the size of a main rotor blade, is analyzed in order to assess the importance of various influences. The findings of this model study suggest that for the slenderness and closed cell construction considered, the refinements are of little importance and a classical type theory is adequate. The potential of elastic tailoring is dramatically demonstrated, so the generality of arbitrary ply layup in the cell wall is needed to exploit this opportunity.

Electrostatics of electron-hole interactions in van der Waals heterostructures

NASA Astrophysics Data System (ADS)

Cavalcante, L. S. R.; Chaves, A.; Van Duppen, B.; Peeters, F. M.; Reichman, D. R.

2018-03-01

The role of dielectric screening of electron-hole interaction in van der Waals heterostructures is theoretically investigated. A comparison between models available in the literature for describing these interactions is made and the limitations of these approaches are discussed. A simple numerical solution of Poisson's equation for a stack of dielectric slabs based on a transfer matrix method is developed, enabling the calculation of the electron-hole interaction potential at very low computational cost and with reasonable accuracy. Using different potential models, direct and indirect exciton binding energies in these systems are calculated within Wannier-Mott theory, and a comparison of theoretical results with recent experiments on excitons in two-dimensional materials is discussed.

The spatial scaling of species interaction networks.

PubMed

Galiana, Nuria; Lurgi, Miguel; Claramunt-López, Bernat; Fortin, Marie-Josée; Leroux, Shawn; Cazelles, Kevin; Gravel, Dominique; Montoya, José M

2018-05-01

Species-area relationships (SARs) are pivotal to understand the distribution of biodiversity across spatial scales. We know little, however, about how the network of biotic interactions in which biodiversity is embedded changes with spatial extent. Here we develop a new theoretical framework that enables us to explore how different assembly mechanisms and theoretical models affect multiple properties of ecological networks across space. We present a number of testable predictions on network-area relationships (NARs) for multi-trophic communities. Network structure changes as area increases because of the existence of different SARs across trophic levels, the preferential selection of generalist species at small spatial extents and the effect of dispersal limitation promoting beta-diversity. Developing an understanding of NARs will complement the growing body of knowledge on SARs with potential applications in conservation ecology. Specifically, combined with further empirical evidence, NARs can generate predictions of potential effects on ecological communities of habitat loss and fragmentation in a changing world.

Potentiality Prediction of Electric Power Replacement Based on Power Market Development Strategy

NASA Astrophysics Data System (ADS)

Miao, Bo; Yang, Shuo; Liu, Qiang; Lin, Jingyi; Zhao, Le; Liu, Chang; Li, Bin

2017-05-01

The application of electric power replacement plays an important role in promoting the development of energy conservation and emission reduction in our country. To exploit the potentiality of regional electric power replacement, the regional GDP (gross domestic product) and energy consumption are taken as potentiality evaluation indicators. The principal component factors are extracted with PCA (principal component analysis), and the integral potentiality analysis is made to the potentiality of electric power replacement in the national various regions; a region is taken as a research object, and the potentiality of electric power replacement is defined and quantified. The analytical model for the potentiality of multi-scenario electric power replacement is developed, and prediction is made to the energy consumption with the grey prediction model. The relevant theoretical research is utilized to realize prediction analysis on the potentiality amount of multi-scenario electric power replacement.

Evidence-based selection of theories for designing behaviour change interventions: using methods based on theoretical construct domains to understand clinicians' blood transfusion behaviour.

PubMed

Francis, Jill J; Stockton, Charlotte; Eccles, Martin P; Johnston, Marie; Cuthbertson, Brian H; Grimshaw, Jeremy M; Hyde, Chris; Tinmouth, Alan; Stanworth, Simon J

2009-11-01

Many theories of behaviour are potentially relevant to predictive and intervention studies but most studies investigate a narrow range of theories. Michie et al. (2005) agreed 12 'theoretical domains' from 33 theories that explain behaviour change. They developed a 'Theoretical Domains Interview' (TDI) for identifying relevant domains for specific clinical behaviours, but the framework has not been used for selecting theories for predictive studies. It was used here to investigate clinicians' transfusion behaviour in intensive care units (ICU). Evidence suggests that red blood cells transfusion could be reduced for some patients without reducing quality of care. (1) To identify the domains relevant to transfusion practice in ICUs and neonatal intensive care units (NICUs), using the TDI. (2) To use the identified domains to select appropriate theories for a study predicting transfusion behaviour. An adapted TDI about managing a patient with borderline haemoglobin by watching and waiting instead of transfusing red blood cells was used to conduct semi-structured, one-to-one interviews with 18 intensive care consultants and neonatologists across the UK. Relevant theoretical domains were: knowledge, beliefs about capabilities, beliefs about consequences, social influences, behavioural regulation. Further analysis at the construct level resulted in selection of seven theoretical approaches relevant to this context: Knowledge-Attitude-Behaviour Model, Theory of Planned Behaviour, Social Cognitive Theory, Operant Learning Theory, Control Theory, Normative Model of Work Team Effectiveness and Action Planning Approaches. This study illustrated, the use of the TDI to identify relevant domains in a complex area of inpatient care. This approach is potentially valuable for selecting theories relevant to predictive studies and resulted in greater breadth of potential explanations than would be achieved if a single theoretical model had been adopted.

Breaking the theoretical scaling limit for predicting quasiparticle energies: the stochastic GW approach.

PubMed

Neuhauser, Daniel; Gao, Yi; Arntsen, Christopher; Karshenas, Cyrus; Rabani, Eran; Baer, Roi

2014-08-15

We develop a formalism to calculate the quasiparticle energy within the GW many-body perturbation correction to the density functional theory. The occupied and virtual orbitals of the Kohn-Sham Hamiltonian are replaced by stochastic orbitals used to evaluate the Green function G, the polarization potential W, and, thereby, the GW self-energy. The stochastic GW (sGW) formalism relies on novel theoretical concepts such as stochastic time-dependent Hartree propagation, stochastic matrix compression, and spatial or temporal stochastic decoupling techniques. Beyond the theoretical interest, the formalism enables linear scaling GW calculations breaking the theoretical scaling limit for GW as well as circumventing the need for energy cutoff approximations. We illustrate the method for silicon nanocrystals of varying sizes with N_{e}>3000 electrons.

Positive Psychology in SLA: An Agenda for Learner and Teacher Wellbeing

ERIC Educational Resources Information Center

Mercer, Sarah

2017-01-01

This article begins with an outline of the developments in Positive Psychology (PP) generally and specifically within SLA focusing on theoretical, empirical and practical developments. It moves on to consider PP's potential contribution to language teaching focusing on how it can help promote emotional, social and psychological wellbeing for…

Exploring Environmental Factors in Nursing Workplaces That Promote Psychological Resilience: Constructing a Unified Theoretical Model.

PubMed

Cusack, Lynette; Smith, Morgan; Hegney, Desley; Rees, Clare S; Breen, Lauren J; Witt, Regina R; Rogers, Cath; Williams, Allison; Cross, Wendy; Cheung, Kin

2016-01-01

Building nurses' resilience to complex and stressful practice environments is necessary to keep skilled nurses in the workplace and ensuring safe patient care. A unified theoretical framework titled Health Services Workplace Environmental Resilience Model (HSWERM), is presented to explain the environmental factors in the workplace that promote nurses' resilience. The framework builds on a previously-published theoretical model of individual resilience, which identified the key constructs of psychological resilience as self-efficacy, coping and mindfulness, but did not examine environmental factors in the workplace that promote nurses' resilience. This unified theoretical framework was developed using a literary synthesis drawing on data from international studies and literature reviews on the nursing workforce in hospitals. The most frequent workplace environmental factors were identified, extracted and clustered in alignment with key constructs for psychological resilience. Six major organizational concepts emerged that related to a positive resilience-building workplace and formed the foundation of the theoretical model. Three concepts related to nursing staff support (professional, practice, personal) and three related to nursing staff development (professional, practice, personal) within the workplace environment. The unified theoretical model incorporates these concepts within the workplace context, linking to the nurse, and then impacting on personal resilience and workplace outcomes, and its use has the potential to increase staff retention and quality of patient care.

Theoretical explanations for maintenance of behaviour change: a systematic review of behaviour theories.

PubMed

Kwasnicka, Dominika; Dombrowski, Stephan U; White, Martin; Sniehotta, Falko

2016-09-01

Behaviour change interventions are effective in supporting individuals in achieving temporary behaviour change. Behaviour change maintenance, however, is rarely attained. The aim of this review was to identify and synthesise current theoretical explanations for behaviour change maintenance to inform future research and practice. Potentially relevant theories were identified through systematic searches of electronic databases (Ovid MEDLINE, Embase, PsycINFO). In addition, an existing database of 80 theories was searched, and 25 theory experts were consulted. Theories were included if they formulated hypotheses about behaviour change maintenance. Included theories were synthesised thematically to ascertain overarching explanations for behaviour change maintenance. Initial theoretical themes were cross-validated. One hundred and seventeen behaviour theories were identified, of which 100 met the inclusion criteria. Five overarching, interconnected themes representing theoretical explanations for behaviour change maintenance emerged. Theoretical explanations of behaviour change maintenance focus on the differential nature and role of motives, self-regulation, resources (psychological and physical), habits, and environmental and social influences from initiation to maintenance. There are distinct patterns of theoretical explanations for behaviour change and for behaviour change maintenance. The findings from this review can guide the development and evaluation of interventions promoting maintenance of health behaviours and help in the development of an integrated theory of behaviour change maintenance.

Theoretical explanations for maintenance of behaviour change: a systematic review of behaviour theories

PubMed Central

Kwasnicka, Dominika; Dombrowski, Stephan U; White, Martin; Sniehotta, Falko

2016-01-01

ABSTRACT Background: Behaviour change interventions are effective in supporting individuals in achieving temporary behaviour change. Behaviour change maintenance, however, is rarely attained. The aim of this review was to identify and synthesise current theoretical explanations for behaviour change maintenance to inform future research and practice. Methods: Potentially relevant theories were identified through systematic searches of electronic databases (Ovid MEDLINE, Embase, PsycINFO). In addition, an existing database of 80 theories was searched, and 25 theory experts were consulted. Theories were included if they formulated hypotheses about behaviour change maintenance. Included theories were synthesised thematically to ascertain overarching explanations for behaviour change maintenance. Initial theoretical themes were cross-validated. Findings: One hundred and seventeen behaviour theories were identified, of which 100 met the inclusion criteria. Five overarching, interconnected themes representing theoretical explanations for behaviour change maintenance emerged. Theoretical explanations of behaviour change maintenance focus on the differential nature and role of motives, self-regulation, resources (psychological and physical), habits, and environmental and social influences from initiation to maintenance. Discussion: There are distinct patterns of theoretical explanations for behaviour change and for behaviour change maintenance. The findings from this review can guide the development and evaluation of interventions promoting maintenance of health behaviours and help in the development of an integrated theory of behaviour change maintenance. PMID:26854092

Potential determinants of health-care professionals' use of survivorship care plans: a qualitative study using the theoretical domains framework.

PubMed

Birken, Sarah A; Presseau, Justin; Ellis, Shellie D; Gerstel, Adrian A; Mayer, Deborah K

2014-11-15

Survivorship care plans are intended to improve coordination of care for the nearly 14 million cancer survivors in the United States. Evidence suggests that survivorship care plans (SCPs) have positive outcomes for survivors, health-care professionals, and cancer programs, and several high-profile organizations now recommend SCP use. Nevertheless, SCP use remains limited among health-care professionals in United States cancer programs. Knowledge of barriers to SCP use is limited in part because extant studies have used anecdotal evidence to identify determinants. This study uses the theoretical domains framework to identify relevant constructs that are potential determinants of SCP use among United States health-care professionals. We conducted semi-structured interviews to assess the relevance of 12 theoretical domains in predicting SCP use among 13 health-care professionals in 7 cancer programs throughout the United States with diverse characteristics. Relevant theoretical domains were identified through thematic coding of interview transcripts, identification of specific beliefs within coded text units, and mapping of specific beliefs onto theoretical constructs. We found the following theoretical domains (based on specific beliefs) to be potential determinants of SCP use: health-care professionals' beliefs about the consequences of SCP use (benefit to survivors, health-care professionals, and the system as a whole); motivation and goals regarding SCP use (advocating SCP use; extent to which using SCPs competed for health-care professionals' time); environmental context and resources (whether SCPs were delivered at a dedicated visit and whether a system, information technology, and funding facilitated SCP use); and social influences (whether using SCPs is an organizational priority, influential people support SCP use, and people who could assist with SCP use buy into using SCPs). Specific beliefs mapped onto the following psychological constructs: outcome expectancies, intrinsic motivation, goal priority, resources, leadership, and team working. Previous studies have explored a limited range of determinants of SCP use. Our findings suggest a more comprehensive list of potential determinants that could be leveraged to promote SCP use. These results are particularly timely as cancer programs face impending SCP use requirements. Future work should develop instruments to measure the potential determinants and assess their relative influence on SCP use.

The water dimer II: Theoretical investigations

NASA Astrophysics Data System (ADS)

Mukhopadhyay, Anamika; Xantheas, Sotiris S.; Saykally, Richard J.

2018-05-01

As the archetype of aqueous hydrogen bonding, the water dimer has been extensively studied by both theory and experiment for nearly seven decades. In this article, we present a detailed chronological review of the theoretical advances made using electronic structure methods to address the structure, hydrogen bonding and vibrational spectroscopy of the water dimer, as well as the role of its potential energy surface in the development of classical force fields to describe intermolecular interactions in clusters and the condensed phases of water.

The Water Dimer II: Theoretical Investigations

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

Mukhopadhyay, Anamika; Xantheas, Sotiris S.; Saykally, Richard J.

As the archetype of aqueous hydrogen bonding, the water dimer has been extensively studied by both theory and experiment for nearly seven decades. Here in this article, we present a detailed chronological review of the theoretical advances made using electronic structure methods to address the structure, hydrogen bonding and vibrational spectroscopy of the water dimer, as well as the role of its potential energy surface in the development of classical force fields to describe intermolecular interaction in clusters and the condensed phases of water.

The Water Dimer II: Theoretical Investigations

DOE PAGES

Mukhopadhyay, Anamika; Xantheas, Sotiris S.; Saykally, Richard J.

2018-03-29

As the archetype of aqueous hydrogen bonding, the water dimer has been extensively studied by both theory and experiment for nearly seven decades. Here in this article, we present a detailed chronological review of the theoretical advances made using electronic structure methods to address the structure, hydrogen bonding and vibrational spectroscopy of the water dimer, as well as the role of its potential energy surface in the development of classical force fields to describe intermolecular interaction in clusters and the condensed phases of water.

Efficient two-component relativistic method for large systems

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

Nakai, Hiromi; Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555; CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012

This paper reviews a series of theoretical studies to develop efficient two-component (2c) relativistic method for large systems by the author’s group. The basic theory is the infinite-order Douglas-Kroll-Hess (IODKH) method for many-electron Dirac-Coulomb Hamiltonian. The local unitary transformation (LUT) scheme can effectively produce the 2c relativistic Hamiltonian, and the divide-and-conquer (DC) method can achieve linear-scaling of Hartree-Fock and electron correlation methods. The frozen core potential (FCP) theoretically connects model potential calculations with the all-electron ones. The accompanying coordinate expansion with a transfer recurrence relation (ACE-TRR) scheme accelerates the computations of electron repulsion integrals with high angular momenta and longmore » contractions.« less

Foreign Scholars' Theoretical Approaches to Using Social Networks as Educational Strategies

ERIC Educational Resources Information Center

Pazyura, Natalia

2017-01-01

Modern trends in development of information and communication technologies change many aspects in the process of education: from the role of participants to the forms and methods of knowledge delivery. ICTs make it possible to develop students' creative potential. The emergence of online social groups was an important event in the sphere of…

Drama and Imagination: A Cognitive Theory of Drama's Effect on Narrative Comprehension and Narrative Production

ERIC Educational Resources Information Center

Mages, Wendy K.

2006-01-01

This article proposes a cognitive theory of how drama affects two aspects of language development: narrative comprehension and narrative production. It is a theoretical model that explicitly posits the role of the imagination in drama's potential to enhance the development of both narrative comprehension and narrative production. (Contains 2…

Theorizing Strategic Human Resource Development: Linking Financial Performance and Sustainable Competitive Advantage

ERIC Educational Resources Information Center

Hu, Po

2007-01-01

This paper is to explore potential new underlying theory of strategic human resource development based on critiques of current theoretical foundations of HRD. It offers a new definition and model of Strategic HRD based on resource-based view of firm and human resource, with linkage to financial performance and competitiveness. Proposed new model…

Expert performance in sport and the dynamics of talent development.

PubMed

Phillips, Elissa; Davids, Keith; Renshaw, Ian; Portus, Marc

2010-04-01

Research on expertise, talent identification and development has tended to be mono-disciplinary, typically adopting genocentric or environmentalist positions, with an overriding focus on operational issues. In this paper, the validity of dualist positions on sport expertise is evaluated. It is argued that, to advance understanding of expertise and talent development, a shift towards a multidisciplinary and integrative science focus is necessary, along with the development of a comprehensive multidisciplinary theoretical rationale. Here we elucidate dynamical systems theory as a multidisciplinary theoretical rationale for capturing how multiple interacting constraints can shape the development of expert performers. This approach suggests that talent development programmes should eschew the notion of common optimal performance models, emphasize the individual nature of pathways to expertise, and identify the range of interacting constraints that impinge on performance potential of individual athletes, rather than evaluating current performance on physical tests referenced to group norms.

Inhabiting the sexual landscape: toward an interpretive theory of the development of sexual orientation and identity.

PubMed

Gordon, Liahna E; Silva, Tony J

2015-01-01

Building on Paula Rust's (1996) concept of a sexual landscape, we propose an interpretive theory of the development of both sexual orientation and sexual identity. We seek to reconcile human agency with active and shifting influences in social context and to recognize the inherent complexity of environmental factors while acknowledging the role that biological potential plays. We ground our model in the insights of three compatible and related theoretical perspectives: social constructionism, symbolic interactionism, and scripting theory. Within this framework, we explain how sexual orientation and sexual identities develop and potentially change.

Open source tools for the information theoretic analysis of neural data.

PubMed

Ince, Robin A A; Mazzoni, Alberto; Petersen, Rasmus S; Panzeri, Stefano

2010-01-01

The recent and rapid development of open source software tools for the analysis of neurophysiological datasets consisting of simultaneous multiple recordings of spikes, field potentials and other neural signals holds the promise for a significant advance in the standardization, transparency, quality, reproducibility and variety of techniques used to analyze neurophysiological data and for the integration of information obtained at different spatial and temporal scales. In this review we focus on recent advances in open source toolboxes for the information theoretic analysis of neural responses. We also present examples of their use to investigate the role of spike timing precision, correlations across neurons, and field potential fluctuations in the encoding of sensory information. These information toolboxes, available both in MATLAB and Python programming environments, hold the potential to enlarge the domain of application of information theory to neuroscience and to lead to new discoveries about how neurons encode and transmit information.

Which Benefits Are Mentioned Most Often in Drug Development Publications?

PubMed

Strüver, Vanessa

2017-01-01

The aim was to identify theoretically expected as well as actually reported benefits from drug development and the importance of individual patient benefits compared to the collective benefits to society in general. Ethical guidelines require that clinical research involving humans offer the potential for benefit. A number of characteristics can be applied to define research benefit. Often benefit is categorized as being either direct or indirect. Indirect benefits can involve collective benefits for society rather than any benefits to the trial patient or subject. The purpose of this review was to examine which potential individual and societal benefits were mentioned as being expected in publications from government experts and which were mentioned in publications describing completed drug development trial results. Literature on research benefit was first identified by searching the PubMed database using several combinations of the key words benefit and clinical research . The search was limited to articles published in English. A Google search with the same combinations of key words but without any language limitation was then performed. Additionally, the reference lists of promising articles were screened for further thematically related articles. Finally, a narrative review was performed of relevant English- and German-language articles published between 1996 and 2016 to identify which of several potential benefits were either theoretically expected or which were mentioned in publications on clinical drug development trial results. The principal benefits from drug development discussed included 2 main types of benefit, namely individual benefits for the patients and collective benefits for society. Twenty-one of an overall total of 26 articles discussing theoretically expected benefits focused on individual patient benefits, whereas 17 out of 26 articles mentioned collective benefits to society. In these publications, the most commonly mentioned theoretically expected individual patient benefit was the chance to receive up-to-date care (38.1%). A general increase in knowledge about health care, treatments, or drugs (70.6%) was the most commonly mentioned theoretically expected benefit for society. In contrast, all 13 publications reporting actual benefits of clinical drug development trials focused on personal benefits and only 1 of these publications also mentioned a societal benefit. The most commonly mentioned individual benefit was an increased quality of life (53.9%), whereas the only mentioned collective benefit to society was a general gain of knowledge (100.0%). Both theoretically expected and actually reported benefits in the majority of the included publications emphasized the importance of individual patient benefits from drug development rather than the collective benefits to society in general. The authors of these publications emphasized the right of each individual patient or subject to look for and expect some personal benefit from participating in a clinical trial rather than considering societal benefit as a top priority. From an ethical point of view, the benefits each individual patient receives from his or her participation in a clinical trial might also be seen as a societal benefit, especially when the drug or device tested, if approved for marketing, would eventually be made available for other similar patients from the country in which the clinical trial was conducted.

Exploring Environmental Factors in Nursing Workplaces That Promote Psychological Resilience: Constructing a Unified Theoretical Model

PubMed Central

Cusack, Lynette; Smith, Morgan; Hegney, Desley; Rees, Clare S.; Breen, Lauren J.; Witt, Regina R.; Rogers, Cath; Williams, Allison; Cross, Wendy; Cheung, Kin

2016-01-01

Building nurses' resilience to complex and stressful practice environments is necessary to keep skilled nurses in the workplace and ensuring safe patient care. A unified theoretical framework titled Health Services Workplace Environmental Resilience Model (HSWERM), is presented to explain the environmental factors in the workplace that promote nurses' resilience. The framework builds on a previously-published theoretical model of individual resilience, which identified the key constructs of psychological resilience as self-efficacy, coping and mindfulness, but did not examine environmental factors in the workplace that promote nurses' resilience. This unified theoretical framework was developed using a literary synthesis drawing on data from international studies and literature reviews on the nursing workforce in hospitals. The most frequent workplace environmental factors were identified, extracted and clustered in alignment with key constructs for psychological resilience. Six major organizational concepts emerged that related to a positive resilience-building workplace and formed the foundation of the theoretical model. Three concepts related to nursing staff support (professional, practice, personal) and three related to nursing staff development (professional, practice, personal) within the workplace environment. The unified theoretical model incorporates these concepts within the workplace context, linking to the nurse, and then impacting on personal resilience and workplace outcomes, and its use has the potential to increase staff retention and quality of patient care. PMID:27242567

[Hypothesis of the compression of morbidity: an example of theoretical development in epidemiology].

PubMed

López-Moreno, S; Corcho-Berdugo, A; López-Cervantes, M

1998-01-01

In this paper we review a hypothesis put forth in 1980 by James Fries under the name of the compression of morbidity, as an example of theoretical development in the field of epidemiology. Initially we discuss some of the essential features of scientific theories and make a historical account of the most important causal models that epidemiology has embraced. Then, the basis for proposing that a compression of the morbidity is taking place are described focusing on its advantages and limitations when it is analyzed from the point of view of structuralism. Finally, we conclude that, to the extent that they are correct, models of this kind have the potential of describing and predicting the evolution of human health; hence, their systematic development entails an extraordinary importance for public health.

Theoretical prediction of airplane stability derivatives at subcritical speeds

NASA Technical Reports Server (NTRS)

Tulinius, J.; Clever, W.; Nieman, A.; Dunn, K.; Gaither, B.

1973-01-01

The theoretical development and application is described of an analysis for predicting the major static and rotary stability derivatives for a complete airplane. The analysis utilizes potential flow theory to compute the surface flow fields and pressures on any configuration that can be synthesized from arbitrary lifting bodies and nonplanar thick lifting panels. The pressures are integrated to obtain section and total configuration loads and moments due side slip, angle of attack, pitching motion, rolling motion, yawing motion, and control surface deflection. Subcritical compressibility is accounted for by means of the Gothert similarity rule.

Macroscopic Quantum-Type Potentials in Theoretical Systems Biology

PubMed Central

Nottale, Laurent

2014-01-01

We review in this paper the use of the theory of scale relativity and fractal space-time as a tool particularly well adapted to the possible development of a future genuine systems theoretical biology. We emphasize in particular the concept of quantum-type potentials, since, in many situations, the effect of the fractality of space—or of the underlying medium—can be reduced to the addition of such a potential energy to the classical equations of motion. Various equivalent representations—geodesic, quantum-like, fluid mechanical, stochastic—of these equations are given, as well as several forms of generalized quantum potentials. Examples of their possible intervention in high critical temperature superconductivity and in turbulence are also described, since some biological processes may be similar in some aspects to these physical phenomena. These potential extra energy contributions could have emerged in biology from the very fractal nature of the medium, or from an evolutive advantage, since they involve spontaneous properties of self-organization, morphogenesis, structuration and multi-scale integration. Finally, some examples of applications of the theory to actual biological-like processes and functions are also provided. PMID:24709901

Trends in entropy production during ecosystem development in the Amazon Basin.

PubMed

Holdaway, Robert J; Sparrow, Ashley D; Coomes, David A

2010-05-12

Understanding successional trends in energy and matter exchange across the ecosystem-atmosphere boundary layer is an essential focus in ecological research; however, a general theory describing the observed pattern remains elusive. This paper examines whether the principle of maximum entropy production could provide the solution. A general framework is developed for calculating entropy production using data from terrestrial eddy covariance and micrometeorological studies. We apply this framework to data from eight tropical forest and pasture flux sites in the Amazon Basin and show that forest sites had consistently higher entropy production rates than pasture sites (0.461 versus 0.422 W m(-2) K(-1), respectively). It is suggested that during development, changes in canopy structure minimize surface albedo, and development of deeper root systems optimizes access to soil water and thus potential transpiration, resulting in lower surface temperatures and increased entropy production. We discuss our results in the context of a theoretical model of entropy production versus ecosystem developmental stage. We conclude that, although further work is required, entropy production could potentially provide a much-needed theoretical basis for understanding the effects of deforestation and land-use change on the land-surface energy balance.

Courseware Design by College Students: The Educational Gains.

ERIC Educational Resources Information Center

Or-Bach, Rachel

2000-01-01

Describes the experience gained during several years of teaching courses on CBT (computer-based training) design to undergraduate students with varying backgrounds and interests. Discusses the theoretical background for the potential benefits; preparation for lifelong learning; information technology literacy and teaching multimedia development; a…

[Health, environment and nursing. Philosophical and theoretical foundations for the development and validation of a nursing interface terminology. Part III].

PubMed

Juvé-Udina, Maria-Eulàlia

2012-06-01

This manuscript is the third of a triad of papers introducing the philosophical and theoretical approaches that support the development and validation of a nursing interface terminology as a standard vocabulary designed to ease data entry into electronic health records, to produce information and to generate knowledge. To analyze the philosophical and theoretical approaches considered in the development of a new nursing interface terminology called ATIC. Review, analysis and discussion of the main philosophical orientations, high and mid-range theories and nursing scientific literature to develop an interpretative conceptualization of the metaparadigm concepts "Health", "Environment" and "Nursing". In the 2 previous papers the ATIC terminology, its foundation on pragmatism, holism, post-positivism and constructivism and the construction of the meaning for the concept elndividualh is discussed. In this third paper, Health is conceptualized as a multidimensional balance state and the concepts of Partial health status, Disease and Being ill are explored within. The analysis of the Environment theories drives its conceptualization as a group of variables that has the potential to affect health status. In this orientation, Nursing is understood as the scientific discipline focused on the study of health status in the particular environment and experience of the individuals, groups, communities or societies. ATIC terminology is rooted on an eclectic philosophical and theoretical foundation, allowing it to be used from different trends within the totality paradigm.

Testing the Consolidated Framework for Implementation Research on health care innovations from South Yorkshire.

PubMed

Ilott, Irene; Gerrish, Kate; Booth, Andrew; Field, Becky

2013-10-01

There is an international imperative to implement research into clinical practice to improve health care. Understanding the dynamics of change requires knowledge from theoretical and empirical studies. This paper presents a novel approach to testing a new meta theoretical framework: the Consolidated Framework for Implementation Research. The utility of the Framework was evaluated using a post hoc, deductive analysis of 11 narrative accounts of innovation in health care services and practice from England, collected in 2010. A matrix, comprising the five domains and 39 constructs of the Framework was developed to examine the coherence of the terminology, to compare results across contexts and to identify new theoretical developments. The Framework captured the complexity of implementation across 11 diverse examples, offering theoretically informed, comprehensive coverage. The Framework drew attention to relevant points in individual cases together with patterns across cases; for example, all were internally developed innovations that brought direct or indirect patient advantage. In 10 cases, the change was led by clinicians. Most initiatives had been maintained for several years and there was evidence of spread in six examples. Areas for further development within the Framework include sustainability and patient/public engagement in implementation. Our analysis suggests that this conceptual framework has the potential to offer useful insights, whether as part of a situational analysis or by developing context-specific propositions for hypothesis testing. Such studies are vital now that innovation is being promoted as core business for health care. © 2012 John Wiley & Sons Ltd.

The Potential Role of Graphene in Developing the Next Generation of Endomaterials

PubMed Central

Matheiken, Sean; Klonaris, Chris

2016-01-01

Graphene is the first 2-dimensional material and possesses a plethora of original properties. Graphene and its derivatives have exhibited a great potential in a number of fields, both medical and nonmedical. The aim of this review is to set the theoretical basis for further research in developing graphene-based endovascular materials. An extensive search was performed in medical and bioengineering literature. Published data on other carbon materials, as well as limited data from medical use of graphene, are promising. Graphene is a promising future material for developing novel endovascular materials. Certain issues as biocompatibility, biotoxicity, and biostability should be explored further. PMID:28025640

Theoretical and Experimental Investigations of the Potential of Osmotic Energy for Power Production †

PubMed Central

Sharif, Adel O.; Merdaw, Ali A.; Aryafar, Maryam; Nicoll, Peter

2014-01-01

This paper presents a study on the potential of osmotic energy for power production. The study includes both pilot plant testing and theoretical modelling as well as cost estimation. A projected cost of £30/MWh of clean electricity could be achieved by using a Hydro-Osmotic Power (HOP) plant if a suitable membrane is used and the osmotic potential difference between the two solutions is greater than 25 bar; a condition that can be readily found in many sites around the world. Results have shown that the membrane system accounts for 50%–80% of the HOP plant cost depending on the salinity difference level. Thus, further development in membrane technology and identifying suitable membranes would have a significant impact on the feasibility of the process and the route to market. As the membrane permeability determines the HOP process feasibility, this paper also describes the effect of the interaction between the fluid and the membrane on the system permeability. It has been shown that both the fluid physical properties as well as the membrane micro-structural parameters need to be considered if further development of the HOP process is to be achieved. PMID:25110959

Theoretical and experimental investigations of the potential of osmotic energy for power production.

PubMed

Sharif, Adel O; Merdaw, Ali A; Aryafar, Maryam; Nicoll, Peter

2014-08-08

This paper presents a study on the potential of osmotic energy for power production. The study includes both pilot plant testing and theoretical modelling as well as cost estimation. A projected cost of £30/MWh of clean electricity could be achieved by using a Hydro-Osmotic Power (HOP) plant if a suitable membrane is used and the osmotic potential difference between the two solutions is greater than 25 bar; a condition that can be readily found in many sites around the world. Results have shown that the membrane system accounts for 50%-80% of the HOP plant cost depending on the salinity difference level. Thus, further development in membrane technology and identifying suitable membranes would have a significant impact on the feasibility of the process and the route to market. As the membrane permeability determines the HOP process feasibility, this paper also describes the effect of the interaction between the fluid and the membrane on the system permeability. It has been shown that both the fluid physical properties as well as the membrane micro-structural parameters need to be considered if further development of the HOP process is to be achieved.

Hydropower assessment of Bolivia—A multisource satellite data and hydrologic modeling approach

USGS Publications Warehouse

Velpuri, Naga Manohar; Pervez, Shahriar; Cushing, W. Matthew

2016-11-28

This study produced a geospatial database for use in a decision support system by the Bolivian authorities to investigate further development and investment potentials in sustainable hydropower in Bolivia. The study assessed theoretical hydropower of all 1-kilometer (km) stream segments in the country using multisource satellite data and a hydrologic modeling approach. With the assessment covering the 2 million square kilometer (km2) region influencing Bolivia’s drainage network, the potential hydropower figures are based on theoretical yield assuming that the systems generating the power are 100 percent efficient. There are several factors to consider when determining the real-world or technical power potential of a hydropower system, and these factors can vary depending on local conditions. Since this assessment covers a large area, it was necessary to reduce these variables to the two that can be modeled consistently throughout the region, streamflow or discharge, and elevation drop or head. First, the Shuttle Radar Topography Mission high-resolution 30-meter (m) digital elevation model was used to identify stream segments with greater than 10 km2 of upstream drainage. We applied several preconditioning processes to the 30-m digital elevation model to reduce errors and improve the accuracy of stream delineation and head height estimation. A total of 316,500 1-km stream segments were identified and used in this study to assess the total theoretical hydropower potential of Bolivia. Precipitation observations from a total of 463 stations obtained from the Bolivian Servicio Nacional de Meteorología e Hidrología (Bolivian National Meteorology and Hydrology Service) and the Brazilian Agência Nacional de Águas (Brazilian National Water Agency) were used to validate six different gridded precipitation estimates for Bolivia obtained from various sources. Validation results indicated that gridded precipitation estimates from the Tropical Rainfall Measuring Mission (TRMM) reanalysis product (3B43) had the highest accuracies. The coarse-resolution (25-km) TRMM data were disaggregated to 5-km pixels using climatology information obtained from the Climate Hazards Group Infrared Precipitation with Stations dataset. About a 17-percent bias was observed in the disaggregated TRMM estimates, which was corrected using the station observations. The bias-corrected, disaggregated TRMM precipitation estimate was used to compute stream discharge using a regionalization approach. In regionalization approach, required homogeneous regions for Bolivia were derived from precipitation patterns and topographic characteristics using a k-means clustering approach. Using the discharge and head height estimates for each 1-km stream segment, we computed hydropower potential for 316,490 stream segments within Bolivia and that share borders with Bolivia. The total theoretical hydropower potential (TTHP) of these stream segments was found to be 212 gigawatts (GW). Out of this total, 77.4 GW was within protected areas where hydropower projects cannot be developed; hence, the remaining total theoretical hydropower in Bolivia (outside the protected areas) was estimated as 135 GW. Nearly 1,000 1-km stream segments, however, were within the boundaries of existing hydropower projects. The TTHP of these stream segments was nearly 1.4 GW, so the residual TTHP of the streams in Bolivia was estimated as 133 GW. Care should be exercised to understand and interpret the TTHP identified in this study because all the stream segments identified and assessed in this study cannot be harnessed to their full capacity; furthermore, factors such as required environmental flows, efficiency, economics, and feasibility need to be considered to better identify a more real-world hydropower potential. If environmental flow requirements of 20–40 percent are considered, the total theoretical power available reduces by 60–80 percent. In addition, a 0.72 efficiency factor further reduces the estimation by another 28 percent. This study provides the base theoretical hydropower potential for Bolivia, the next step is to identify optimal hydropower plant locations and factor in the principles to appraise a real-world power potential in Bolivia.

Facilitating Multiple Intelligences through Multimodal Learning Analytics

ERIC Educational Resources Information Center

Perveen, Ayesha

2018-01-01

This paper develops a theoretical framework for employing learning analytics in online education to trace multiple learning variations of online students by considering their potential of being multiple intelligences based on Howard Gardner's 1983 theory of multiple intelligences. The study first emphasizes the need to facilitate students as…

Lehae-La-Rona: Epistemological Interrogations to Broaden Our Conception of Environment and Sustainability

ERIC Educational Resources Information Center

Mokuku, Tsepo

2012-01-01

This paper develops and explores "lehae-la-rona" and its potential value in environment and sustainability discourse. It draws on African-centred concepts and critiques of dominant Eurocentric theoretical frameworks. In particular, Ani's concepts of "asili," "utamawazo" and "utamaroho" and Indigenous…

Advantages of Structure-Based Drug Design Approaches in Neurological Disorders

PubMed Central

Aarthy, Murali; Panwar, Umesh; Selvaraj, Chandrabose; Singh, Sanjeev Kumar

2017-01-01

Objective: The purpose of the review is to portray the theoretical concept on neurological disorders from research data. Background: The freak changes in chemical response of nerve impulse causes neurological disorders. The research evidence of the effort done in the older history suggests that the biological drug targets and their effective feature with responsive drugs could be valuable in promoting the future development of health statistics structure for improved treatment for curing the nervous disorders. Methods: In this review, we summarized the most iterative theoretical concept of structure based drug design approaches in various neurological disorders to unfathomable understanding of reported information for future drug design and development. Results: On the premise of reported information we analyzed the model of theoretical drug designing process for understanding the mechanism and pathology of the neurological diseases which covers the development of potentially effective inhibitors against the biological drug targets. Finally, it also suggests the management and implementation of the current treatment in improving the human health system behaviors. Conclusion: With the survey of reported information we concluded the development strategies of diagnosis and treatment against neurological diseases which leads to supportive progress in the drug discovery. PMID:28042767

Density functional theory and phytochemical study of 8-hydroxyisodiospyrin

NASA Astrophysics Data System (ADS)

Ullah, Zakir; Ata-ur-Rahman; Fazl-i-Sattar; Rauf, Abdur; Yaseen, Muhammad; Hassan, Waseem; Tariq, Muhammad; Ayub, Khurshid; Tahir, Asif Ali; Ullah, Habib

2015-09-01

Comprehensive theoretical and experimental studies of a natural product, 8-hydroxyisodiospyrin (HDO) have been carried out. Based on the correlation of experimental and theoretical data, an appropriate computational model was developed for obtaining the electronic, spectroscopic, and thermodynamic parameters of HDO. First of all, the exact structure of HDO is confirmed from the nice correlation of theory and experiment, prior to determination of its electroactive nature. Hybrid density functional theory (DFT) is employed for all theoretical simulations. The experimental and predicted IR and UV-vis spectra [B3LYP/6-31+G(d,p) level of theory] have excellent correlation. Inter-molecular non-covalent interaction of HDO with different gases such as NH3, CO2, CO, H2O is investigated through geometrical counterpoise (gCP) i.e., B3LYP-gCP-D3/6-31G∗ method. Furthermore, the inter-molecular interaction is also supported by geometrical parameters, electronic properties, thermodynamic parameters and charge analysis. All these characterizations have corroborated each other and confirmed the electroactive nature (non-covalent interaction ability) of HDO for the studied gases. Electronic properties such as Ionization Potential (IP), Electron Affinities (EA), electrostatic potential (ESP), density of states (DOS), HOMO, LUMO, and band gap of HDO have been estimated for the first time theoretically.

A promising new thermoelectric material - Ruthenium silicide

NASA Technical Reports Server (NTRS)

Vining, Cronin B.; Mccormack, Joseph A.; Zoltan, Andrew; Zoltan, Leslie D.

1991-01-01

Experimental and theoretical efforts directed toward increasing thermoelectric figure of merit values by a factor of 2 or 3 have been encouraging in several respects. An accurate and detailed theoretical model developed for n-type silicon-germanium (SiGe) indicates that ZT values several times higher than currently available are expected under certain conditions. These new, high ZT materials are expected to be significantly different from SiGe, but not unreasonably so. Several promising candidate materials have been identified which may meet the conditions required by theory. One such candidate, ruthenium silicide, currently under development at JPL, has been estimated to have the potential to exhibit figure of merit values 4 times higher than conventional SiGe materials. Recent results are summarized.

High-level theoretical rovibrational spectroscopy beyond fc-CCSD(T): The C3 molecule.

PubMed

Schröder, Benjamin; Sebald, Peter

2016-01-28

An accurate local (near-equilibrium) potential energy surface (PES) is reported for the C3 molecule in its electronic ground state (X̃(1)Σg (+)). Special care has been taken in the convergence of the potential relative to high-order correlation effects, core-valence correlation, basis set size, and scalar relativity. Based on the aforementioned PES, several rovibrational states of all (12)C and (13)C substituted isotopologues have been investigated, and spectroscopic parameters based on term energies up to J = 30 have been calculated. Available experimental vibrational term energies are reproduced to better than 1 cm(-1) and rotational constants show relative errors of not more than 0.01%. The equilibrium bond length has been determined in a mixed experimental/theoretical approach to be 1.294 07(10) Å in excellent agreement with the ab initio composite value of 1.293 97 Å. Theoretical band intensities based on a newly developed electric dipole moment function also suggest that the infrared active (1, 1(1), 0)←(0, 0(0), 0) combination band might be observable by high-resolution spectroscopy.

Theoretical analysis, design and development of a 27-MHz folded loop antenna as a potential applicator in hyperthermia treatment.

PubMed

Kouloulias, Vassilis; Karanasiou, Irene; Giamalaki, Melina; Matsopoulos, George; Kouvaris, John; Kelekis, Nikolaos; Uzunoglu, Nikolaos

2015-02-01

A hyperthermia system using a folded loop antenna applicator at 27 MHz for soft tissue treatment was investigated both theoretically and experimentally to evaluate its clinical value. The electromagnetic analysis of a 27-MHz folded loop antenna for use in human tissue was based on a customised software tool and led to the design and development of the proposed hyperthermia system. The system was experimentally validated using specific absorption rate (SAR) distribution estimations through temperature distribution measurements of a muscle tissue phantom after electromagnetic exposure. Various scenarios for optimal antenna positioning were also performed. Comparison of the theoretical and experimental analysis results shows satisfactory agreement. The SAR level of 50% reaches 8 cm depth in the tissue phantom. Thus, based on the maximum observed SAR values that were of the order of 100 W/kg, the antenna specified is suitable for deep tumour heating. Theoretical and experimental SAR distribution results as derived from this study are in agreement. The proposed folded loop antenna seems appropriate for use in hyperthermia treatment, achieving proper planning and local treatment of deeply seated affected areas and lesions.

The Theoretical Distribution of Evoked Brainstem Activity in Preterm, High-Risk, and Healthy Infants.

ERIC Educational Resources Information Center

Salamy, A.

1981-01-01

Determines the frequency distribution of Brainstem Auditory Evoked Potential variables (BAEP) for premature babies at different stages of development--normal newborns, infants, young children, and adults. The author concludes that the assumption of normality underlying most "standard" statistical analyses can be met for many BAEP…

Postgraduate Students as OER Capacitators

ERIC Educational Resources Information Center

King, Thomas William

2017-01-01

A comprehensive theoretical, legal and practical basis for OER has been developed over the past fifteen years, supported by the expansion of open source curation platforms and the work of advocacy groups and international bodies. OER's potential has been sufficiently documented; the question remains how best to support, integrate and normalise OER…

Antecedents to Organizational Performance: Theoretical and Practical Implications for Aircraft Maintenance Officer Force Development

DTIC Science & Technology

2015-03-26

to my reader, Lieutenant Colonel Robert Overstreet, for helping solidify my research, coaching me through the statistical analysis, and positive...61  Descriptive Statistics .............................................................................................................. 61...common-method bias requires careful assessment of potential sources of bias and implementing procedural and statistical control methods. Podsakoff

(Re)conceptualizing International Student Mobility: The Potential of Transnational Social Fields

ERIC Educational Resources Information Center

Gargano, Terra

2009-01-01

Although educational border crossings are not new, the creation of innovative theoretical constructs, such as transnational social fields, to examine the flow of students and social networks across national borders is a profound development. Within transnational social fields, a constant flow of ideas and practices is embedded within…

Transmedia Dynamics in Education: The Case of Robot Heart Stories

ERIC Educational Resources Information Center

Gambarato, Renira Rampazzo; Dabagian, Lilit

2016-01-01

This article discusses the potentiality and risks of applying transmedia storytelling strategies in the realm of education. The empirical approach is used to analyze the experiential education project Robot Heart Stories, developed in 2011 in Canada and the United States. The theoretical framework focuses on the conceptualization of transmedia…

Breastfeeding Is Positively Associated with Child Intelligence Even Net of Parental IQ

ERIC Educational Resources Information Center

Kanazawa, Satoshi

2015-01-01

Some previous reviews conclude that breastfeeding is not significantly associated with increased intelligence in children once mother's IQ is statistically controlled. The conclusion may potentially have both theoretical and methodological problems. The National Child Development Study allows the examination of the effect of breastfeeding on…

THEORETICAL DEVELOPMENT AND ANALYTICAL SOLUTIONS FOR TRANSPORT OF VOLATILE ORGANIC COMPOUNDS IN DUAL-POROSITY SOILS

EPA Science Inventory

Predicting the behavior of volatile organic compounds in soils or sediments is necessary for managing their use and designing appropriate remedial systems to eliminate potential threats to the environment, particularly the air and groundwater resources. In this effort, based on c...

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.

[Does co-operation research provide approaches to explain the changes in the German hospital market?].

PubMed

Raible, C; Leidl, R

2004-11-01

The German hospital market faces an extensive process of consolidation. In this change hospitals consider cooperation as one possibility to improve competitiveness. To investigate explanations of changes in the German hospital market by theoretical approaches of cooperation research. The aims and mechanism of the theories, their relevance in terms of contents and their potential for empirical tests were used as criteria to assess the approaches, with current and future trends in the German hospital market providing the framework. Based on literature review, six theoretical approaches were investigated: industrial organization, transaction cost theory, game theory, resource dependency, institutional theory, and co-operative investment and finance theory. In addition, the data needed to empirically test the theories were specified. As a general problem, some of the theoretical approaches set a perfect market as a precondition. This precondition is not met by the heavily regulated German hospital market. Given the current regulations and the assessment criteria, industrial organization as well as resource-dependency and institutional theory approaches showed the highest potential to explain various aspects of the changes in the hospital market. So far, none of the approaches investigated provides a comprehensive and empirically tested explanation of the changes in the German hospital market. However, some of the approaches provide a theoretical background for part of the changes. As this dynamic market is economically of high significance, there is a need for further development and empirical testing of relevant theoretical approaches.

Facilitating progress in health behaviour theory development and modification: the reasoned action approach as a case study.

PubMed

Head, Katharine J; Noar, Seth M

2014-01-01

This paper explores the question: what are barriers to health behaviour theory development and modification, and what potential solutions can be proposed? Using the reasoned action approach (RAA) as a case study, four areas of theory development were examined: (1) the theoretical domain of a theory; (2) tension between generalisability and utility, (3) criteria for adding/removing variables in a theory, and (4) organisational tracking of theoretical developments and formal changes to theory. Based on a discussion of these four issues, recommendations for theory development are presented, including: (1) the theoretical domain for theories such as RAA should be clarified; (2) when there is tension between generalisability and utility, utility should be given preference given the applied nature of the health behaviour field; (3) variables should be formally removed/amended/added to a theory based on their performance across multiple studies and (4) organisations and researchers with a stake in particular health areas may be best suited for tracking the literature on behaviour-specific theories and making refinements to theory, based on a consensus approach. Overall, enhancing research in this area can provide important insights for more accurately understanding health behaviours and thus producing work that leads to more effective health behaviour change interventions.

Theoretical study of a dual harmonic system and its application to the CSNS/RCS

NASA Astrophysics Data System (ADS)

Yuan, Yao-Shuo; Wang, Na; Xu, Shou-Yan; Yuan, Yue; Wang, Sheng

2015-12-01

Dual harmonic systems have been widely used in high intensity proton synchrotrons to suppress the space charge effect, as well as reduce the beam loss. To investigate the longitudinal beam dynamics in a dual rf system, the potential well, the sub-buckets in the bunch and the multi-solutions of the phase equation are studied theoretically in this paper. Based on these theoretical studies, optimization of bunching factor and rf voltage waveform are made for the dual harmonic rf system in the upgrade phase of the China Spallation Neutron Source Rapid Cycling Synchrotron (CSNS/RCS). In the optimization process, the simulation with space charge effect is done using a newly developed code, C-SCSIM. Supported by National Natural Science Foundation of China (11175193)

Total Electron-Impact Ionization Cross-Sections of CFx and NFx (x = 1 - 3)

NASA Technical Reports Server (NTRS)

Huo, Winifred M.; Tarnovsky, Vladimir; Becker, Kurt H.; Kwak, Dochan (Technical Monitor)

2001-01-01

The discrepancy between experimental and theoretical total electron-impact ionization cross sections for a group of fluorides, CFx, and NFx, (x = 1 - 3), is attributed to the inadequacies in previous theoretical models. Cross-sections calculated using a recently developed siBED (simulation Binary-Encounter-Dipole) model that takes into account the shielding of the long-range dipole potential between the scattering electron and target are in agreement with experimentation. The present study also carefully reanalyzed the previously reported experimental data to account for the possibility of incomplete collection of fragment ions and the presence of ion-pair formation channels. For NF3, our experimental and theoretical cross-sections compare well with the total ionization cross-sections recently reported by Haaland et al. in the region below dication formation.

Estimating 3D positions and velocities of projectiles from monocular views.

PubMed

Ribnick, Evan; Atev, Stefan; Papanikolopoulos, Nikolaos P

2009-05-01

In this paper, we consider the problem of localizing a projectile in 3D based on its apparent motion in a stationary monocular view. A thorough theoretical analysis is developed, from which we establish the minimum conditions for the existence of a unique solution. The theoretical results obtained have important implications for applications involving projectile motion. A robust, nonlinear optimization-based formulation is proposed, and the use of a local optimization method is justified by detailed examination of the local convexity structure of the cost function. The potential of this approach is validated by experimental results.

Nuclear clustering and the electron screening puzzle

NASA Astrophysics Data System (ADS)

Bertulani, C. A.; Spitaleri, C.

2018-01-01

Electron screening changes appreciably the magnitude of astrophysical nuclear reactions within stars. This effect is also observed in laboratory experiments on Earth, where atomic electrons are present in the nuclear targets. Theoretical models were developed over the past 30 years and experimental measurements have been carried out to study electron screening in thermonuclear reactions. None of the theoretical models were able to explain the high values of the experimentally determined screening potentials. We explore the possibility that the "electron screening puzzle" is due to nuclear clusterization and polarization e_ects in the fusion reactions. We will discuss the supporting arguments for this scenario.

Examining the potential contribution of social theory to developing and supporting Australian Indigenous-mainstream health service partnerships.

PubMed

Haynes, Emma; Taylor, Kate P; Durey, Angela; Bessarab, Dawn; Thompson, Sandra C

2014-09-20

The substantial gap in life expectancy between Indigenous and non-Indigenous Australians has been slow to improve, despite increased dedicated funding. Partnerships between Australian Indigenous and mainstream Western biomedical organisations are recognised as crucial to improved Indigenous health outcomes. However, these partnerships often experience challenges, particularly in the context of Australia's race and political relations. We examined the relevant literature in order to identify the potential role for social theory and theoretical models in developing and maintaining intercultural partnerships. Having identified relevant theoretical models, terms and possible key words, a range of databases were searched and relevant articles selected for inclusion. An integrative approach brought together theoretical models and practical considerations about working in partnership, to inform our analysis of the literature. Considering partnerships between Australian Indigenous and mainstream health organisations as 'bi-cultural' is simplistic: rather they are culturally diverse across social and professional levels. As such, partnerships between Australian Indigenous and mainstream health organisations may be better conceptualised as 'intercultural', operating across diverse and shifting cultural frames of reference. Theories identified by this review as useful to guide partnerships include power relations, reflexivity and dialogue, borders and strangeness and the intercultural or third space. This paper examines how these theoretical approaches can develop understanding and improve intercultural engagement between mainstream and Australian Indigenous partners in healthcare. Rather than viewing partnerships merely as arrangements between disembodied entities, sometimes contractual in nature, they are better seen as activities between people and organisations and essentially dependent on relationships, occurring in an intercultural space that is complex, dynamic and subject to changes in power relations. Theoretical models aiming to understand and improve partnerships indicate the complexity of building and maintaining such partnerships and stress the importance of understanding factors that can strengthen or derail their effectiveness. While the theories presented here are by no means exhaustive, they nonetheless provide a series of entry points through which to engage with the issue and expand the discourse. This approach allows the transformative nature of Australian Indigenous-mainstream 'culture' to be explored and understood in its lived expression; rather than relegated to prescriptive categories.

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

Attachment and Chronic Pain in Children and Adolescents

PubMed Central

Donnelly, Theresa J.; Jaaniste, Tiina

2016-01-01

Although attachment theory is not new, its theoretical implications for the pediatric chronic pain context have not been thoroughly considered, and the empirical implications and potential clinical applications are worth exploring. The attachment framework broadly focuses on interactions between a child’s developing self-regulatory systems and their caregiver’s responses. These interactions are believed to create a template for how individuals will relate to others in the future, and may help account for normative and pathological patterns of emotions and behavior throughout life. This review outlines relevant aspects of the attachment framework to the pediatric chronic pain context. The theoretical and empirical literature is reviewed regarding the potential role of attachment-based constructs such as vulnerability and maintaining factors of pediatric chronic pain. The nature and targets of attachment-based pediatric interventions are considered, with particular focus on relevance for the pediatric chronic pain context. The potential role of attachment style in the transition from acute to chronic pain is considered, with further research directions outlined. PMID:27792141

A Relationship Between the 2-body Energy of Kaxiras Pandey and Pearson Takai Halicioglu Tiller Potential Functions

NASA Astrophysics Data System (ADS)

Lim, Teik-Cheng

2004-01-01

A parametric relationship between the Pearson Takai Halicioglu Tiller (PTHT) and the Kaxiras Pandey (KP) empirical potential energy functions is developed for the case of 2-body interaction. The need for such relationship arises when preferred parametric data and adopted software correspond to different potential functions. The analytical relationship was obtained by equating the potential functions' derivatives at zeroth, first and second order with respect to the interatomic distance at the equilibrium bond length, followed by comparison of coefficients in the repulsive and attractive terms. Plots of non-dimensional 2-body energy versus the nondimensional interatomic distance verified the analytical relationships developed herein. The discrepancy revealed in theoretical plots suggests that the 2-body PTHT and KP potentials are more suitable for curve-fitting "softer" and "harder" bonds respectively.

Fundamental transport mechanisms, fabrication and potential applications of nanoporous atomically thin membranes.

PubMed

Wang, Luda; Boutilier, Michael S H; Kidambi, Piran R; Jang, Doojoon; Hadjiconstantinou, Nicolas G; Karnik, Rohit

2017-06-06

Graphene and other two-dimensional materials offer a new approach to controlling mass transport at the nanoscale. These materials can sustain nanoscale pores in their rigid lattices and due to their minimum possible material thickness, high mechanical strength and chemical robustness, they could be used to address persistent challenges in membrane separations. Here we discuss theoretical and experimental developments in the emerging field of nanoporous atomically thin membranes, focusing on the fundamental mechanisms of gas- and liquid-phase transport, membrane fabrication techniques and advances towards practical application. We highlight potential functional characteristics of the membranes and discuss applications where they are expected to offer advantages. Finally, we outline the major scientific questions and technological challenges that need to be addressed to bridge the gap from theoretical simulations and proof-of-concept experiments to real-world applications.

Potential calculation of rural settlements consolidation: a case study of Tianchang City in Anhui Province

NASA Astrophysics Data System (ADS)

Zhao, Xiaofeng; Huang, Xianjin; Li, Li; Fan, Jing

2011-02-01

Rural settlements consolidation plays an important role for improving the rural residential habitation, and increasing the intensive land use. This paper aims to analyze the current situation, features and problems of rural settlements, and calculate the theoretical and realistic potential of rural settlements consolidation in Tianchang City, in order to provide references for new round of land use planning. Methods of field survey, hierarchy analysis, land targets per capita, modified coefficient on limited conditions and GIS is employed. The results indicate that: (1) The total area of rural settlements was 15,496.31hm2 in 2005, and the area of rural settlements per capita was 332.66m2, far more than standard of 150m2. (2) The comprehensive modified coefficient in 15 towns is from 0.47 to 0.96, which indicates the ability and possibility of the realization of theoretical potential. (3) The theoretical potential is 9,746.09 hm2 and the realistic potential is 7,124.94hm2 from 2005 to 2020. (4) The spatial distribution between rate of theoretical potential and realistic potential is incompletely consistent.

Moving towards an Integrated Theory of Policy Networks: A Multi-Theoretical Approach for Examining State-Level Policy Change in U.S. Subsystems. Working Paper #45

ERIC Educational Resources Information Center

Galey, Sarah; Youngs, Peter

2014-01-01

Scholars have developed a wide range of theories to explain both stability and change in policy subsystems. In recent years, a burgeoning literature has emerged that focuses on the application of network analysis in policy research, more formally known as Policy Network Analysis (PNA). This approach, while still developing, has great potential as…

Conceptual Influences on Induction: A Case for a Late Onset

PubMed Central

Sloutsky, Vladimir M.; (Sophia) Deng, Wei; Fisher, Anna V.; Kloos, Heidi

2015-01-01

This research examines the mechanism of early induction, the development of induction, and the ways attentional and conceptual factors contribute to induction across development. Different theoretical views offer different answers to these questions. Six experiments with 4- and 5-year-olds, 7-year-olds and adults (N = 208) test these competing theories by teaching categories for which category membership and perceptual similarity are in conflict, and varying orthogonally conceptual and attentional factors that may potentially affect inductive inference. The results suggest that early induction is similarity-based; conceptual information plays a negligible role in early induction, but its role increases gradually, with the 7-year-olds being a transitional group. And finally, there is substantial contribution of attention to the development of induction: only adults, but not children, could perform category-based induction without attentional support. Therefore, category-based induction exhibits protracted development, with attentional factors contributing early in development and conceptual factors contributing later in development. These results are discussed in relation to existing theories of development of inductive inference and broader theoretical views on cognitive development. PMID:26350681

Plasmonics of 2D Nanomaterials: Properties and Applications

PubMed Central

Li, Yu; Li, Ziwei; Chi, Cheng; Shan, Hangyong; Zheng, Liheng

2017-01-01

Plasmonics has developed for decades in the field of condensed matter physics and optics. Based on the classical Maxwell theory, collective excitations exhibit profound light‐matter interaction properties beyond classical physics in lots of material systems. With the development of nanofabrication and characterization technology, ultra‐thin two‐dimensional (2D) nanomaterials attract tremendous interest and show exceptional plasmonic properties. Here, we elaborate the advanced optical properties of 2D materials especially graphene and monolayer molybdenum disulfide (MoS2), review the plasmonic properties of graphene, and discuss the coupling effect in hybrid 2D nanomaterials. Then, the plasmonic tuning methods of 2D nanomaterials are presented from theoretical models to experimental investigations. Furthermore, we reveal the potential applications in photocatalysis, photovoltaics and photodetections, based on the development of 2D nanomaterials, we make a prospect for the future theoretical physics and practical applications. PMID:28852608

HIGH-TEMPERATURE, SHORT-TIME SULFATION OF CALCIUM- BASED SORBENTS. 1. THEORETICAL SULFATION MODEL

EPA Science Inventory

A mathematical model for the sulfation of CaO is developed around the overlapping grain concept. The potential influence of high mass-transfer rates from simultaneous calcination of CaCO3 or Ca(OH)2 is incorporated in the mass-transfer coefficient for SO2 diffusion to the partic...

"But What Can I Do?": Three Necessary Tensions in Teaching Teachers about Race

ERIC Educational Resources Information Center

Pollock, Mica; Deckman, Sherry; Mira, Meredith; Shalaby, Carla

2010-01-01

A core question of teacher education--"What can I do?"--plagues courses on race in particular ways. Teachers struggle for "concrete" applications of "theoretical" ideas about race, question the potential for "everyday" activity to dismantle inequality "structures," and wrestle with the need for both professional and personal development on racial…

Executive Function and Language in Deaf Children

ERIC Educational Resources Information Center

Figueras, Berta; Edwards, Lindsey; Langdon, Dawn

2008-01-01

The relationship between language and executive function (EF) and their development in children have been the focus of recent debate and are of theoretical and clinical importance. Exploration of these functions in children with a peripheral hearing loss has the potential to be informative from both perspectives. This study compared the EF and…

Community Service and Social Responsibility in Youth.

ERIC Educational Resources Information Center

Youniss, James; Yates, Miranda

This book presents a theoretical rationale for youth involvement in community service. Its thesis is that youth participation in solving social problems has the potential to promote the development of personal and collective identity. Through community service, youth can acquire a sense that they can make a difference and a concern for society's…

Using ePortfolio's to Assess Undergraduate Paramedic Students: A Proof of Concept Evaluation

ERIC Educational Resources Information Center

Mason, Rod; Williams, Brett

2016-01-01

The ePortfolio presents itself as potentially a highly useful assessment tool for students, encouraging self-reflection and the development of both clinical skills and theoretical knowledge by students identifying strengths and gaps in knowledge. A survey of students after the completion the inaugural Emergency Health ePortfolio program revealed…

An inverse problem for a semilinear parabolic equation arising from cardiac electrophysiology

NASA Astrophysics Data System (ADS)

Beretta, Elena; Cavaterra, Cecilia; Cerutti, M. Cristina; Manzoni, Andrea; Ratti, Luca

2017-10-01

In this paper we develop theoretical analysis and numerical reconstruction techniques for the solution of an inverse boundary value problem dealing with the nonlinear, time-dependent monodomain equation, which models the evolution of the electric potential in the myocardial tissue. The goal is the detection of an inhomogeneity \

The Internet as Potential Equalizer: New Leverage for Confronting Social Irresponsibility.

ERIC Educational Resources Information Center

Coombs, W. Timothy

1998-01-01

Contends activists have a new weapon (the Internet) which can change the organization-stakeholder dynamic. Uses recent development in stakeholder theory to explain how the Internet, when used effectively, can allow activist groups to become more powerful and to command the attention of organizations. Illustrates the theoretical points presented…

Dynamic and Interactive Mathematics Learning Environments: The Case of Teaching the Limit Concept

ERIC Educational Resources Information Center

Martinovic, Dragana; Karadag, Zekeriya

2012-01-01

This theoretical study is an attempt to explore the potential of the dynamic and interactive mathematics learning environments (DIMLE) in relation to the technological pedagogical content knowledge (TPACK) framework. DIMLE are developed with intent to support learning mathematics through free exploration in a less constrained environment. A…

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

Huang, Chen; Perez, Danny; Voter, Arthur F.

Hyperdynamics is a powerful method to significantly extend the time scales amenable to molecular dynamics simulation of infrequent events. One outstanding challenge, however, is the development of the so-called bias potential required by the method. In this work, we design a bias potential using information about all minimum energy pathways (MEPs) out of the current state. While this approach is not suitable for use in an actual hyperdynamics simulation, because the pathways are generally not known in advance, it allows us to show that it is possible to come very close to the theoretical boost limit of hyperdynamics while maintainingmore » high accuracy. We demonstrate this by applying this MEP-based hyperdynamics (MEP-HD) to metallic surface diffusion systems. In most cases, MEP-HD gives boost factors that are orders of magnitude larger than the best existing bias potential, indicating that further development of hyperdynamics bias potentials could have a significant payoff. Lastly, we discuss potential practical uses of MEP-HD, including the possibility of developing MEP-HD into a true hyperdynamics.« less

A model for calculating the vertical distribution of the atmospheric electric potential in the exchange layer in a maritime clean atmosphere

NASA Astrophysics Data System (ADS)

Kulkarni, M. N.; Kamra, A. K.

2012-11-01

A theoretical model is developed for calculating the vertical distribution of atmospheric electric potential in exchange layer of maritime clean atmosphere. The transport of space charge in electrode layer acts as a convective generator in this model and plays a major role in determining potential distribution in vertical. Eddy diffusion is the main mechanism responsible for the distribution of space charge in vertical. Our results show that potential at a particular level increases with increase in the strength of eddy diffusion under similar conditions. A method is suggested to estimate columnar resistance, the ionospheric potential and the vertical atmospheric electric potential distribution in exchange layer from measurements of total air-earth current density and surface electric field made over oceans. The results are validated and found to be in very good agreement with the previous aircraft measurements. Different parameters involved in the proposed methodology can be determined either theoretically, as in the present work, or experimentally using the near surface atmospheric electrical measurements or using some other surface-based measurement technique such as LIDAR. A graphical relationship between the atmospheric eddy diffusion coefficient and height of exchange layer obtained from atmospheric electrical approach, is reported.

Full-potential theoretical investigations of electron inelastic mean free paths and extended x-ray absorption fine structure in molybdenum.

PubMed

Chantler, C T; Bourke, J D

2014-04-09

X-ray absorption fine structure (XAFS) spectroscopy is one of the most robust, adaptable, and widely used structural analysis tools available for a range of material classes from bulk solids to aqueous solutions and active catalytic structures. Recent developments in XAFS theory have enabled high-accuracy calculations of spectra over an extended energy range using full-potential cluster modelling, and have demonstrated particular sensitivity in XAFS to a fundamental electron transport property-the electron inelastic mean free path (IMFP). We develop electron IMFP theory using a unique hybrid model that simultaneously incorporates second-order excitation losses, while precisely accounting for optical transitions dictated by the complex band structure of the solid. These advances are coupled with improved XAFS modelling to determine wide energy-range absorption spectra for molybdenum. This represents a critical test case of the theory, as measurements of molybdenum K-edge XAFS represent the most accurate determinations of XAFS spectra for any material. We find that we are able to reproduce an extended range of oscillatory structure in the absorption spectrum, and demonstrate a first-time theoretical determination of the absorption coefficient of molybdenum over the entire extended XAFS range utilizing a full-potential cluster model.

Achieving Land, Energy, and Environmental Compatibility: Utility-Scale Solar Energy Potential and Land-Use in California

NASA Astrophysics Data System (ADS)

Hoffacker, M. K.; Hernandez, R. R.; Field, C. B.

2013-12-01

Solar energy is an archetype renewable energy technology with great potential to reduce greenhouse gas emissions when substituted for carbon-intensive energy. Utility-scale solar energy (USSE; i.e., > 1 MW) necessitates large quantities of space making the efficient use of land for USSE development critical to realizing its full potential. However, studies elucidating the interaction between land-use and utility-scale solar energy (USSE) are limited. In this study, we assessed 1) the theoretical and technical potential of terrestrial-based USSE systems, and 2) land-use and land-cover change impacts from actual USSE installations (> 20 MW; planned, under construction, operating), using California as a case study due to its early adoption of renewable energy systems, unique constraints on land availability, immense energy demand, and vast natural resources. We used topo-climatic (e.g., slope, irradiance), infrastructural (e.g., proximity to transmission lines), and ecological constraints (e.g., threatened and endangered species) to determine highly favorable, favorable, and unfavorable locations for USSE and to assess its technical potential. We found that the theoretical potential of photovoltaic (PV) and concentrating solar power (CSP) in California is 26,097 and 29,422 kWh/m2/day, respectively. We identified over 150 planned, under construction, and operating USSE installations in California, ranging in size from 20 to 1,000 MW. Currently, 29% are located on shrub- and scrublands, 23% on cultivated crop land, 13% on pasture/hay areas, 11% on grassland/herbaceous and developed open space, and 7% in the built environment. Understanding current land-use decisions of USSE systems and assessing its future potential can be instructive for achieving land, energy, and environmental compatibility, especially for other global regions that share similar resource demands and limitations.

Towards unsupervised polyaromatic hydrocarbons structural assignment from SA-TIMS-FTMS data.

PubMed

Benigni, Paolo; Marin, Rebecca; Fernandez-Lima, Francisco

2015-10-01

With the advent of high resolution ion mobility analyzers and their coupling to ultrahigh resolution mass spectrometers, there is a need to further develop a theoretical workflow capable of correlating experimental accurate mass and mobility measurements with tridimensional candidate structures. In the present work, a general workflow is described for unsupervised tridimensional structural assignment based on accurate mass measurements, mobility measurements, in silico 2D-3D structure generation, and theoretical mobility calculations. In particular, the potential of this workflow will be shown for the analysis of polyaromatic hydrocarbons from Coal Tar SRM 1597a using selected accumulation - trapped ion mobility spectrometry (SA-TIMS) coupled to Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). The proposed workflow can be adapted to different IMS scenarios, can utilize different collisional cross-section calculators and has the potential to include MS n and IMS n measurements for faster and more accurate tridimensional structural assignment.

Game Intelligence in Team Sports

PubMed Central

Lennartsson, Jan; Lidström, Nicklas; Lindberg, Carl

2015-01-01

We set up a game theoretic framework to analyze a wide range of situations from team sports. A fundamental idea is the concept of potential; the probability of the offense scoring the next goal minus the probability that the next goal is made by the defense. We develop categorical as well as continuous models, and obtain optimal strategies for both offense and defense. A main result is that the optimal defensive strategy is to minimize the maximum potential of all offensive strategies. PMID:25970581

Boost-phase discrimination research activities

NASA Technical Reports Server (NTRS)

Cooper, David M.; Deiwert, George S.

1989-01-01

Theoretical research in two areas was performed. The aerothermodynamics research focused on the hard-body and rocket plume flows. Analytical real gas models to describe finite rate chemistry were developed and incorporated into the three-dimensional flow codes. New numerical algorithms capable of treating multi-species reacting gas equations and treating flows with large gradients were also developed. The computational chemistry research focused on the determination of spectral radiative intensity factors, transport properties and reaction rates. Ab initio solutions to the Schrodinger equation provided potential energy curves transition moments (radiative probabilities and strengths) and potential energy surfaces. These surfaces were then coupled with classical particle reactive trajectories to compute reaction cross-sections and rates.

Andreev reflection enhancement in semiconductor-superconductor structures

NASA Astrophysics Data System (ADS)

Bouscher, Shlomi; Winik, Roni; Hayat, Alex

2018-02-01

We develop a theoretical approach for modeling a wide range of semiconductor-superconductor structures with arbitrary potential barriers and a spatially dependent superconducting order parameter. We demonstrate asymmetry in the conductance spectrum as a result of a Schottky barrier shape. We further show that the Andreev reflection process can be significantly enhanced through resonant tunneling with appropriate barrier configuration, which can incorporate the Schottky barrier as a contributing component of the device. Moreover, we show that resonant tunneling can be achieved in superlattice structures as well. These theoretically demonstrated effects along with our modeling approach enable much more efficient Cooper pair injection into semiconductor-superconductor structures, including superconducting optoelectronic devices.

A set-theoretic model reference adaptive control architecture for disturbance rejection and uncertainty suppression with strict performance guarantees

NASA Astrophysics Data System (ADS)

Arabi, Ehsan; Gruenwald, Benjamin C.; Yucelen, Tansel; Nguyen, Nhan T.

2018-05-01

Research in adaptive control algorithms for safety-critical applications is primarily motivated by the fact that these algorithms have the capability to suppress the effects of adverse conditions resulting from exogenous disturbances, imperfect dynamical system modelling, degraded modes of operation, and changes in system dynamics. Although government and industry agree on the potential of these algorithms in providing safety and reducing vehicle development costs, a major issue is the inability to achieve a-priori, user-defined performance guarantees with adaptive control algorithms. In this paper, a new model reference adaptive control architecture for uncertain dynamical systems is presented to address disturbance rejection and uncertainty suppression. The proposed framework is predicated on a set-theoretic adaptive controller construction using generalised restricted potential functions.The key feature of this framework allows the system error bound between the state of an uncertain dynamical system and the state of a reference model, which captures a desired closed-loop system performance, to be less than a-priori, user-defined worst-case performance bound, and hence, it has the capability to enforce strict performance guarantees. Examples are provided to demonstrate the efficacy of the proposed set-theoretic model reference adaptive control architecture.

Low loss GaN waveguides at the visible spectral wavelengths for integrated photonics applications.

PubMed

Chen, Hong; Fu, Houqiang; Huang, Xuanqi; Zhang, Xiaodong; Yang, Tsung-Han; Montes, Jossue A; Baranowski, Izak; Zhao, Yuji

2017-12-11

We perform comprehensive studies on the fundamental loss mechanisms in III-nitride waveguides in the visible spectral region. Theoretical analysis shows that free carrier loss dominates for GaN under low photon power injection. When optical power increases, the two photon absorption loss becomes important and eventually dominates when photon energy above half-bandgap of GaN. When the dimensions of the waveguides reduce, the sidewall scattering loss will start to dominate. To verify the theoretical results, a high performance GaN-on-sapphire waveguide was fabricated and characterized. Experimental results are consistent with the theoretical findings, showing that under high power injection the optical loss changed significantly for GaN waveguides. A low optical loss ~2 dB/cm was achieved on the GaN waveguide, which is the lowest value ever reported for the visible spectral range. The results and fabrication processes developed in this work pave the way for the development of III-nitride integrated photonics in the visible and potentially ultraviolet spectral range for nonlinear optics and quantum photonics applications.

Hyperdynamics boost factor achievable with an ideal bias potential

DOE PAGES

Huang, Chen; Perez, Danny; Voter, Arthur F.

2015-08-20

Hyperdynamics is a powerful method to significantly extend the time scales amenable to molecular dynamics simulation of infrequent events. One outstanding challenge, however, is the development of the so-called bias potential required by the method. In this work, we design a bias potential using information about all minimum energy pathways (MEPs) out of the current state. While this approach is not suitable for use in an actual hyperdynamics simulation, because the pathways are generally not known in advance, it allows us to show that it is possible to come very close to the theoretical boost limit of hyperdynamics while maintainingmore » high accuracy. We demonstrate this by applying this MEP-based hyperdynamics (MEP-HD) to metallic surface diffusion systems. In most cases, MEP-HD gives boost factors that are orders of magnitude larger than the best existing bias potential, indicating that further development of hyperdynamics bias potentials could have a significant payoff. Lastly, we discuss potential practical uses of MEP-HD, including the possibility of developing MEP-HD into a true hyperdynamics.« less

Modelling foraging movements of diving predators: a theoretical study exploring the effect of heterogeneous landscapes on foraging efficiency

PubMed Central

Bartoń, Kamil A.; Scott, Beth E.; Travis, Justin M.J.

2014-01-01

Foraging in the marine environment presents particular challenges for air-breathing predators. Information about prey capture rates, the strategies that diving predators use to maximise prey encounter rates and foraging success are still largely unknown and difficult to observe. As well, with the growing awareness of potential climate change impacts and the increasing interest in the development of renewable sources it is unknown how the foraging activity of diving predators such as seabirds will respond to both the presence of underwater structures and the potential corresponding changes in prey distributions. Motivated by this issue we developed a theoretical model to gain general understanding of how the foraging efficiency of diving predators may vary according to landscape structure and foraging strategy. Our theoretical model highlights that animal movements, intervals between prey capture and foraging efficiency are likely to critically depend on the distribution of the prey resource and the size and distribution of introduced underwater structures. For multiple prey loaders, changes in prey distribution affected the searching time necessary to catch a set amount of prey which in turn affected the foraging efficiency. The spatial aggregation of prey around small devices (∼ 9 × 9 m) created a valuable habitat for a successful foraging activity resulting in shorter intervals between prey captures and higher foraging efficiency. The presence of large devices (∼ 24 × 24 m) however represented an obstacle for predator movement, thus increasing the intervals between prey captures. In contrast, for single prey loaders the introduction of spatial aggregation of the resources did not represent an advantage suggesting that their foraging efficiency is more strongly affected by other factors such as the timing to find the first prey item which was found to occur faster in the presence of large devices. The development of this theoretical model represents a useful starting point to understand the energetic reasons for a range of potential predator responses to spatial heterogeneity and environmental uncertainties in terms of search behaviour and predator–prey interactions. We highlight future directions that integrated empirical and modelling studies should take to improve our ability to predict how diving predators will be impacted by the deployment of manmade structures in the marine environment. PMID:25250211

A theoretical treatment of technical risk in modern propulsion system design

NASA Astrophysics Data System (ADS)

Roth, Bryce Alexander

2000-09-01

A prevalent trend in modern aerospace systems is increasing complexity and cost, which in turn drives increased risk. Consequently, there is a clear and present need for the development of formalized methods to analyze the impact of risk on the design of aerospace vehicles. The objective of this work is to develop such a method that enables analysis of risk via a consistent, comprehensive treatment of aerothermodynamic and mass properties aspects of vehicle design. The key elements enabling the creation of this methodology are recent developments in the analytical estimation of work potential based on the second law of thermodynamics. This dissertation develops the theoretical foundation of a vehicle analysis method based on work potential and validates it using the Northrop F-5E with GE J85-GE-21 engines as a case study. Although the method is broadly applicable, emphasis is given to aircraft propulsion applications. Three work potential figures of merit are applied using this method: exergy, available energy, and thrust work potential. It is shown that each possesses unique properties making them useful for specific vehicle analysis tasks, though the latter two are actually special cases of exergy. All three are demonstrated on the analysis of the J85-GE-21 propulsion system, resulting in a comprehensive description of propulsion system thermodynamic loss. This "loss management" method is used to analyze aerodynamic drag loss of the F-5E and is then used in conjunction with the propulsive loss model to analyze the usage of fuel work potential throughout the F-5E design mission. The results clearly show how and where work potential is used during flight and yield considerable insight as to where the greatest opportunity for design improvement is. Next, usage of work potential is translated into fuel weight so that the aerothermodynamic performance of the F-5E can be expressed entirely in terms of vehicle gross weight. This technique is then applied as a means to quantify the impact of engine cycle technologies on the F-5E airframe. Finally, loss management methods are used in conjunction with probabilistic analysis methods to quantify the impact of risk on F-5E aerothermodynamic performance.

An empirical/theoretical model with dimensionless numbers to predict the performance of electrodialysis systems on the basis of operating conditions.

PubMed

Karimi, Leila; Ghassemi, Abbas

2016-07-01

Among the different technologies developed for desalination, the electrodialysis/electrodialysis reversal (ED/EDR) process is one of the most promising for treating brackish water with low salinity when there is high risk of scaling. Multiple researchers have investigated ED/EDR to optimize the process, determine the effects of operating parameters, and develop theoretical/empirical models. Previously published empirical/theoretical models have evaluated the effect of the hydraulic conditions of the ED/EDR on the limiting current density using dimensionless numbers. The reason for previous studies' emphasis on limiting current density is twofold: 1) to maximize ion removal, most ED/EDR systems are operated close to limiting current conditions if there is not a scaling potential in the concentrate chamber due to a high concentration of less-soluble salts; and 2) for modeling the ED/EDR system with dimensionless numbers, it is more accurate and convenient to use limiting current density, where the boundary layer's characteristics are known at constant electrical conditions. To improve knowledge of ED/EDR systems, ED/EDR models should be also developed for the Ohmic region, where operation reduces energy consumption, facilitates targeted ion removal, and prolongs membrane life compared to limiting current conditions. In this paper, theoretical/empirical models were developed for ED/EDR performance in a wide range of operating conditions. The presented ion removal and selectivity models were developed for the removal of monovalent ions and divalent ions utilizing the dominant dimensionless numbers obtained from laboratory scale electrodialysis experiments. At any system scale, these models can predict ED/EDR performance in terms of monovalent and divalent ion removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Predictors of E-Learning Satisfaction in Teaching and Learning for School Teachers: A Literature Review

ERIC Educational Resources Information Center

Cheok, Mei Lick; Wong, Su Luan

2015-01-01

This paper develops a theoretical model of the determinants of e-learning satisfaction in teaching and learning among secondary school teachers. It is based on reviews of past studies on satisfaction in using information technology systems. Three potential groups of determinants of satisfaction among secondary school teachers were identified;…

Reading and Computers: Issues for Theory and Practice. Computers and Education Series.

ERIC Educational Resources Information Center

Reinking, David, Ed.

Embodying two themes--that the computer can become an even more exciting instructional tool than it is today, and that the research necessary for developing the potential of this tool is already underway, this book explores the theoretical, research, and instructional issues concerning computers and reading. The titles of the essays and their…

Developing the Therapeutic Potential of Embodied Cognition and Metaphors in Nature-Based Therapy: Lessons from Theory to Practice

ERIC Educational Resources Information Center

Corazon, Sus S.; Schilhab, Theresa S. S.; Stigsdotter, Ulrika K.

2011-01-01

This paper theoretically examines the interplay between cognition and bodily involvement in relation to nature-based therapy and proposes implications for practice. With support from theory within embodied cognition and neuroscientific studies, it is argued that explicit learning is actively supported by bodily involvement with the environment.…

A Primary Prevention Program to Reduce Bulimia and Anorexia Nervosa.

ERIC Educational Resources Information Center

Cullari, Salvatore; Redmon, William K.

This paper presents a theoretical model for a primary prevention program for bulimia and anorexia nervosa to be used with adolescents and young women considered most at risk of developing these eating disorders. Characteristics of potential anorexics and bulimics are identified to aid in the selection of target groups for the program. It is…

Alternative Theoretical Bases for the Study of Human Communication: The Rules Perspective.

ERIC Educational Resources Information Center

Cushman, Donald P.

Three potentially useful perspectives for the scientific development of human communication theory are the law model, the systems approach, and the rules paradigm. It is the purpose of this paper to indicate the utility of the rules perspective. For the purposes of this analysis, human communication is viewed as the successful transfer of symbolic…

Environmental Scanning: How Developed Is Information Acquisition in Western European Companies?

ERIC Educational Resources Information Center

Benczúr, David

2005-01-01

Introduction: A number of theoretical works focus on the potential revolutionary impact of the Internet and other Information and Communication Technologies (ICT) upon Competitive Intelligence, but only a few empirical research papers can be found on it. Is the real impact still unknown, or is it too insignificant to talk about? The present paper…

Body Image as a Mediator of Non-Suicidal Self-Injury in Adolescents

ERIC Educational Resources Information Center

Muehlenkamp, Jennifer J.; Brausch, Amy M.

2012-01-01

Attitudes towards the body have been largely overlooked as a potential risk factor for adolescent non-suicidal self-injury (NSSI) despite theorizing that a negative body image may play a critical role in the development of this behavior. The current study used structural equation modeling to evaluate the fit of a theoretical model specifying body…

Comment on "Social Contagion, Adolescent Sexual Behavior, and Pregnancy: A Nonlinear Dynamic EMOSA Model."

ERIC Educational Resources Information Center

Stoolmiller, Mike

1998-01-01

Examines the Rodgers, Rowe, and Buster (1998) epidemic model of the onset of social activities for adolescent sexuality. Maintains that its strengths include its theoretical potential to generate new hypotheses for further testing at the individual level. Asserts that its limitations include the lack of a well-developed statistical framework and…

Emotion and emotion regulation: from another perspective.

PubMed

Langlois, Judith H

2004-01-01

An overview of the content of the From Another Perspective collection on emotion and emotion regulation is provided. The lead article identifies fundamental issues of definition and the commentaries represent varying theoretical and methodological perspectives on emotion and emotion regulation. Together, the articles discuss the promises and pitfalls of emotion research and its potential for understanding child development.

Predicting the potential distribution of invasive exotic species using GIS and information-theoretic approaches: A case of ragweed (Ambrosia artemisiifolia L.) distribution in China

USGS Publications Warehouse

Hao, Chen; LiJun, Chen; Albright, Thomas P.

2007-01-01

Invasive exotic species pose a growing threat to the economy, public health, and ecological integrity of nations worldwide. Explaining and predicting the spatial distribution of invasive exotic species is of great importance to prevention and early warning efforts. We are investigating the potential distribution of invasive exotic species, the environmental factors that influence these distributions, and the ability to predict them using statistical and information-theoretic approaches. For some species, detailed presence/absence occurrence data are available, allowing the use of a variety of standard statistical techniques. However, for most species, absence data are not available. Presented with the challenge of developing a model based on presence-only information, we developed an improved logistic regression approach using Information Theory and Frequency Statistics to produce a relative suitability map. This paper generated a variety of distributions of ragweed (Ambrosia artemisiifolia L.) from logistic regression models applied to herbarium specimen location data and a suite of GIS layers including climatic, topographic, and land cover information. Our logistic regression model was based on Akaike's Information Criterion (AIC) from a suite of ecologically reasonable predictor variables. Based on the results we provided a new Frequency Statistical method to compartmentalize habitat-suitability in the native range. Finally, we used the model and the compartmentalized criterion developed in native ranges to "project" a potential distribution onto the exotic ranges to build habitat-suitability maps. ?? Science in China Press 2007.

Estimating the Economic Potential of Offshore Wind in the United States

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

Beiter, P.; Musial, W.; Smith, A.

The potential for cost reduction and market deployment for offshore wind varies considerably within the United States. This analysis estimates the future economic viability of offshore wind at more than 7,000 sites under a variety of electric sector and cost reduction scenarios. Identifying the economic potential of offshore wind at a high geospatial resolution can capture the significant variation in local offshore resource quality, costs, and revenue potential. In estimating economic potential, this article applies a method initially developed in Brown et al. (2015) to offshore wind and estimates the sensitivity of results under a variety of most likely electricmore » sector scenarios. For the purposes of this analysis, a theoretical framework is developed introducing a novel offshore resource classification system that is analogous to established resource classifications from the oil and gas sector. Analyzing economic potential within this framework can help establish a refined understanding across industries of the technology and site-specific risks and opportunities associated with future offshore wind development. The results of this analysis are intended to inform the development of the U.S. Department of Energy's offshore wind strategy.« less

Theoretical Approaches in Evolutionary Ecology: Environmental Feedback as a Unifying Perspective.

PubMed

Lion, Sébastien

2018-01-01

Evolutionary biology and ecology have a strong theoretical underpinning, and this has fostered a variety of modeling approaches. A major challenge of this theoretical work has been to unravel the tangled feedback loop between ecology and evolution. This has prompted the development of two main classes of models. While quantitative genetics models jointly consider the ecological and evolutionary dynamics of a focal population, a separation of timescales between ecology and evolution is assumed by evolutionary game theory, adaptive dynamics, and inclusive fitness theory. As a result, theoretical evolutionary ecology tends to be divided among different schools of thought, with different toolboxes and motivations. My aim in this synthesis is to highlight the connections between these different approaches and clarify the current state of theory in evolutionary ecology. Central to this approach is to make explicit the dependence on environmental dynamics of the population and evolutionary dynamics, thereby materializing the eco-evolutionary feedback loop. This perspective sheds light on the interplay between environmental feedback and the timescales of ecological and evolutionary processes. I conclude by discussing some potential extensions and challenges to our current theoretical understanding of eco-evolutionary dynamics.

Α-aryl-N-alkyl nitrones, as potential agents for stroke treatment: synthesis, theoretical calculations, antioxidant, anti-inflammatory, neuroprotective, and brain-blood barrier permeability properties.

PubMed

Chioua, Mourad; Sucunza, David; Soriano, Elena; Hadjipavlou-Litina, Dimitra; Alcázar, Alberto; Ayuso, Irene; Oset-Gasque, María Jesús; González, María Pilar; Monjas, Leticia; Rodríguez-Franco, María Isabel; Marco-Contelles, José; Samadi, Abdelouahid

2012-01-12

We report the synthesis, theoretical calculations, the antioxidant, anti-inflammatory, and neuroprotective properties, and the ability to cross the blood-brain barrier (BBB) of (Z)-α-aryl and heteroaryl-N-alkyl nitrones as potential agents for stroke treatment. The majority of nitrones compete with DMSO for hydroxyl radicals, and most of them are potent lipoxygenase inhibitors. Cell viability-related (MTT assay) studies clearly showed that nitrones 1-3 and 10 give rise to significant neuroprotection. When compounds 1-11 were tested for necrotic cell death (LDH release test) nitrones 1-3, 6, 7, and 9 proved to be neuroprotective agents. In vitro evaluation of the BBB penetration of selected nitrones 1, 2, 10, and 11 using the PAMPA-BBB assay showed that all of them cross the BBB. Permeable quinoline nitrones 2 and 3 show potent combined antioxidant and neuroprotective properties and, therefore, can be considered as new lead compounds for further development in specific tests for potential stroke treatment.

Computational crystallization

PubMed Central

Altan, Irem; Charbonneau, Patrick; Snell, Edward H.

2016-01-01

Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed. PMID:26792536

On the Performance Potential of Bioelectrochemical Life Support Systems

NASA Technical Reports Server (NTRS)

Mansell, J. Matthew

2013-01-01

An area of growing multi-disciplinary research and revolutionary development for bio-processing on Earth is bioelectrochemical systems. These systems exploit the capability of many microorganisms to act as biocatalysts, enhancing the performance of electrochemical processes which convert low-value materials into valuable products. Many varieties of such processes hold potential value for space exploration as means to recycle metabolic waste and other undesirable materials or insitu resources into oxygen, water, and other valuable substances. However, the wide range of possible reactants, products, configurations, and operating parameters, along with the early stage of development and application on the ground necessitate thorough consideration of which, if any, possibilities could outperform existing technologies and should thus receive investment for space applications. In turn, the decision depends on the theoretical and practical limits of performance and the value of the reactant-product conversions within spaceflight scenarios, and should, to the greatest extent possible, be examined from the perspective of a fully designed, integrated system, rather than as an isolated unit lacking critical components like valves and pumps. Herein, we select a series of possible reactant-product conversions, develop concept process flow diagrams for each, and estimate theoretical and (where sufficient literature data allows) practical performance limitations of each. The objective was to estimate the costs, benefits, and risks of each concept in order to aid strategic decisions in the early-phase technology development effort.

[Ethical perspectives on E‑health and health apps : Is all that is achievable desirable?

PubMed

Groß, Dominik; Schmidt, Mathias

2018-03-01

The aim of technical innovation-and the standpoint from which to assess technology-must be to expand human spaces of action and improve social coexistence. Although many current developments have the potential for furthering this aim, they also imply the danger of being misused. The potential for misuse can be recognized and dealt with at an early stage if ethics is an integral part of technology development. Relevant evaluation criteria include benefit and damage potential, possible repercussions on the physician-patient relationship, self-efficacy, and self-determination (autonomy) of the actors based on full knowledge, appropriate attribution of responsibility, and the access and distribution of rights.This report meditates on the ethical evaluation of E‑health and the role of ethics in developing new medical technologies. It first discusses the effects of the digitalization of the healthcare market on patients and health workers and then reconsiders the potential, framework, and instruments of ethical evaluation from a theoretical and application-oriented point of view.

Theoretical study of modulated multi-layer SPR device for improved refractive index sensing

NASA Astrophysics Data System (ADS)

Mohapatra, Saswat; Moirangthem, Rakesh S.

2018-02-01

In the present work, a theoretical investigation of Surface Plasmon Resonance (SPR) properties of a multilayer film (Au-SiO2-Au) coated on a glass prism is being carried out. In this multilayer structure, each interface corresponds to multiple SPR modes. To obtain the maximum reflection dips in the SPR modes, the thickness of SiO2 layer is optimized by varying it from 100-600 nm. Our calculation also reveals that SPR mode corresponding to Au-ambient interface is very sensitive to the changes in the surrounding medium, least affecting other SPR modes. The sensing performance of the proposed nano-plasmonic sensor is theoretically calculated using bulk refractive index sensing. Such multilayer SPR sensing device has advantages over conventional SPR devices in terms of their bulk sensitivity and self-referencing, claiming itself as a potential candidate for the development of highly sensitive biological sensor.

Voltage-Clamp Studies on Uterine Smooth Muscle

PubMed Central

Anderson, Nels C.

1969-01-01

These studies have developed and tested an experimental approach to the study of membrane ionic conductance mechanisms in strips of uterine smooth muscle. The experimental and theoretical basis for applying the double sucrose-gap technique is described along with the limitations of this system. Nonpropagating membrane action potentials were produced in response to depolarizing current pulses under current-clamp conditions. The stepwise change of membrane potential under voltage-clamp conditions resulted in a family of ionic currents with voltage- and time-dependent characteristics. In sodium-free solution the peak transient current decreased and its equilibrium potential shifted along the voltage axis toward a more negative internal potential. These studies indicate a sodium-dependent, regenerative excitation mechanism. PMID:5796366

ISS Plasma Interaction: Measurements and Modeling

NASA Technical Reports Server (NTRS)

Barsamian, H.; Mikatarian, R.; Alred, J.; Minow, J.; Koontz, S.

2004-01-01

Ionospheric plasma interaction effects on the International Space Station are discussed in the following paper. The large structure and high voltage arrays of the ISS represent a complex system interacting with LEO plasma. Discharge current measurements made by the Plasma Contactor Units and potential measurements made by the Floating Potential Probe delineate charging and magnetic induction effects on the ISS. Based on theoretical and physical understanding of the interaction phenomena, a model of ISS plasma interaction has been developed. The model includes magnetic induction effects, interaction of the high voltage solar arrays with ionospheric plasma, and accounts for other conductive areas on the ISS. Based on these phenomena, the Plasma Interaction Model has been developed. Limited verification of the model has been performed by comparison of Floating Potential Probe measurement data to simulations. The ISS plasma interaction model will be further tested and verified as measurements from the Floating Potential Measurement Unit become available, and construction of the ISS continues.

Assessing implementation difficulties in tobacco use prevention and cessation counselling among dental providers.

PubMed

Amemori, Masamitsu; Michie, Susan; Korhonen, Tellervo; Murtomaa, Heikki; Kinnunen, Taru H

2011-05-26

Tobacco use adversely affects oral health. Clinical guidelines recommend that dental providers promote tobacco abstinence and provide patients who use tobacco with brief tobacco use cessation counselling. Research shows that these guidelines are seldom implemented, however. To improve guideline adherence and to develop effective interventions, it is essential to understand provider behaviour and challenges to implementation. This study aimed to develop a theoretically informed measure for assessing among dental providers implementation difficulties related to tobacco use prevention and cessation (TUPAC) counselling guidelines, to evaluate those difficulties among a sample of dental providers, and to investigate a possible underlying structure of applied theoretical domains. A 35-item questionnaire was developed based on key theoretical domains relevant to the implementation behaviours of healthcare providers. Specific items were drawn mostly from the literature on TUPAC counselling studies of healthcare providers. The data were collected from dentists (n = 73) and dental hygienists (n = 22) in 36 dental clinics in Finland using a web-based survey. Of 95 providers, 73 participated (76.8%). We used Cronbach's alpha to ascertain the internal consistency of the questionnaire. Mean domain scores were calculated to assess different aspects of implementation difficulties and exploratory factor analysis to assess the theoretical domain structure. The authors agreed on the labels assigned to the factors on the basis of their component domains and the broader behavioural and theoretical literature. Internal consistency values for theoretical domains varied from 0.50 ('emotion') to 0.71 ('environmental context and resources'). The domain environmental context and resources had the lowest mean score (21.3%; 95% confidence interval [CI], 17.2 to 25.4) and was identified as a potential implementation difficulty. The domain emotion provided the highest mean score (60%; 95% CI, 55.0 to 65.0). Three factors were extracted that explain 70.8% of the variance: motivation (47.6% of variance, α = 0.86), capability (13.3% of variance, α = 0.83), and opportunity (10.0% of variance, α = 0.71). This study demonstrated a theoretically informed approach to identifying possible implementation difficulties in TUPAC counselling among dental providers. This approach provides a method for moving from diagnosing implementation difficulties to designing and evaluating interventions.

Development of theory-based health messages: three-phase programme of formative research

PubMed Central

Epton, Tracy; Norman, Paul; Harris, Peter; Webb, Thomas; Snowsill, F. Alexandra; Sheeran, Paschal

2015-01-01

Online health behaviour interventions have great potential but their effectiveness may be hindered by a lack of formative and theoretical work. This paper describes the process of formative research to develop theoretically and empirically based health messages that are culturally relevant and can be used in an online intervention to promote healthy lifestyle behaviours among new university students. Drawing on the Theory of Planned Behaviour, a three-phase programme of formative research was conducted with prospective and current undergraduate students to identify (i) modal salient beliefs (the most commonly held beliefs) about fruit and vegetable intake, physical activity, binge drinking and smoking, (ii) which beliefs predicted intentions/behaviour and (iii) reasons underlying each of the beliefs that could be targeted in health messages. Phase 1, conducted with 96 pre-university college students, elicited 56 beliefs about the behaviours. Phase 2, conducted with 3026 incoming university students, identified 32 of these beliefs that predicted intentions/behaviour. Phase 3, conducted with 627 current university students, elicited 102 reasons underlying the 32 beliefs to be used to construct health messages to bolster or challenge these beliefs. The three-phase programme of formative research provides researchers with an example of how to develop health messages with a strong theoretical- and empirical base for use in health behaviour change interventions. PMID:24504361

Theoretical and experimental prediction of the redox potentials of metallocene compounds

NASA Astrophysics Data System (ADS)

Li, Ya-Ping; Liu, Hai-Bo; Liu, Tao; Yu, Zhang-Yu

2017-11-01

The standard redox electrode potential ( E°) values of metallocene compounds are obtained theoretically with density functional theory (DFT) method at B3LYP/6-311++G( d, p) level and experimentally with cyclic voltammetry (CV). The theoretical E° values of metallocene compounds are in good agreement with experimental ones. We investigate the substituent effects on the redox properties of metallocene compounds. Among the four metallocene compounds, the E° values is largest for titanocene dichloride and smallest for ferrocene.

Can we Build on Social Movement Theories to Develop and Improve Community-Based Participatory Research? A Framework Synthesis Review.

PubMed

Tremblay, Marie-Claude; Martin, Debbie H; Macaulay, Ann C; Pluye, Pierre

2017-06-01

A long-standing challenge in community-based participatory research (CBPR) has been to anchor practice and evaluation in a relevant and comprehensive theoretical framework of community change. This study describes the development of a multidimensional conceptual framework that builds on social movement theories to identify key components of CBPR processes. Framework synthesis was used as a general literature search and analysis strategy. An initial conceptual framework was developed from the theoretical literature on social movement. A literature search performed to identify illustrative CBPR projects yielded 635 potentially relevant documents, from which eight projects (corresponding to 58 publications) were retained after record and full-text screening. Framework synthesis was used to code and organize data from these projects, ultimately providing a refined framework. The final conceptual framework maps key concepts of CBPR mobilization processes, such as the pivotal role of the partnership; resources and opportunities as necessary components feeding the partnership's development; the importance of framing processes; and a tight alignment between the cause (partnership's goal), the collective action strategy, and the system changes targeted. The revised framework provides a context-specific model to generate a new, innovative understanding of CBPR mobilization processes, drawing on existing theoretical foundations. © 2017 The Authors American Journal of Community Psychology published by Wiley Periodicals, Inc. on behalf of Society for Community Research and Action.

Models and theories of prescribing decisions: A review and suggested a new model.

PubMed

Murshid, Mohsen Ali; Mohaidin, Zurina

2017-01-01

To date, research on the prescribing decisions of physician lacks sound theoretical foundations. In fact, drug prescribing by doctors is a complex phenomenon influenced by various factors. Most of the existing studies in the area of drug prescription explain the process of decision-making by physicians via the exploratory approach rather than theoretical. Therefore, this review is an attempt to suggest a value conceptual model that explains the theoretical linkages existing between marketing efforts, patient and pharmacist and physician decision to prescribe the drugs. The paper follows an inclusive review approach and applies the previous theoretical models of prescribing behaviour to identify the relational factors. More specifically, the report identifies and uses several valuable perspectives such as the 'persuasion theory - elaboration likelihood model', the stimuli-response marketing model', the 'agency theory', the theory of planned behaviour,' and 'social power theory,' in developing an innovative conceptual paradigm. Based on the combination of existing methods and previous models, this paper suggests a new conceptual model of the physician decision-making process. This unique model has the potential for use in further research.

Theoretical and Experimental Insights into the Dissociation of 2-Hydroxyethylhydrazinium Nitrate Clusters Formed via Electrospray.

PubMed

Patrick, Amanda L; Vogelhuber, Kristen M; Prince, Benjamin D; Annesley, Christopher J

2018-03-01

Ionic liquids are used for myriad applications, including as catalysts, solvents, and propellants. Specifically, 2-hydroxyethylhydrazinium nitrate (HEHN) has been developed as a chemical propellant for space applications. The gas-phase behavior of HEHN ions and clusters is important in understanding its potential as an electrospray thruster propellant. Here, the unimolecular dissociation pathways of two clusters are experimentally observed, and theoretical modeling of hydrogen bonding and dissociation pathways is used to help rationalize those observations. The cation/deprotonated cation cluster [HEH 2 - H] + , which is observed from electrospray ionization, is calculated to be considerably more stable than the complementary cation/protonated anion adduct, [HEH + HNO 3 ] + , which is not observed experimentally. Upon collisional activation, a larger cluster [(HEHN) 2 HEH] + undergoes dissociation via loss of nitric acid at lower collision energies, as predicted theoretically. At higher collision energies, additional primary and secondary loss pathways open, including deprotonated cation loss, ion-pair loss, and double-nitric-acid loss. Taken together, these experimental and theoretical results contribute to a foundational understanding of the dissociation of protic ionic liquid clusters in the gas phase.

An Integrative Approach to Curriculum Development in Higher Education in the USA: A Theoretical Framework

ERIC Educational Resources Information Center

Khan, Mohammad Ayub; Law, Laurie Smith

2015-01-01

The role of curriculum in higher education is sine quo non for the provision of quality and relevant educational programs and services to the current and potential learners in the USA and elsewhere in the world. Regardless of sizes, types or origins, curriculum is considered the heart and soul of all educational institutions. Curriculum is crucial…

Searching Nearest Potential of Children with Intellectual Disability--Dynamic Assessment

ERIC Educational Resources Information Center

Kulesza, Ewa Maria

2015-01-01

The article discussed the issue of the diagnosis with the use of task-support-task procedure. A theoretical model of diagnosis based on the concepts by L. S. Vygotski, R. Case, and A. Bandura was described and developed. The model was tested on a group of non-disabled preschool children, and children with mild and moderate intellectual disability…

Generation Y, Learner Autonomy and the Potential of Web 2.0 Tools for Language Learning and Teaching

ERIC Educational Resources Information Center

Morgan, Liam

2012-01-01

Purpose: The purpose of this paper is to examine the relationship between the development of learner autonomy and the application of Web 2.0 tools in the language classroom. Design/methodology/approach: The approach taken is that of qualitative action research within an explicit theoretical framework and the data were collected via surveys and…

The Potential of Studying Specific Language Impairment in Bilinguals for Linguistic Research on Specific Language Impairment in Monolinguals

ERIC Educational Resources Information Center

Rothweiler, Monika

2010-01-01

In her Keynote Article, Paradis discusses the role of the interface between bilingual development and specific language impairment (SLI) on two different levels. On the level of theoretical explanations of SLI, Paradis asks how domain general versus domain-specific perspectives on SLI can account for bilingual SLI, as well as what bilingual SLI…

Proof and Proving in the Classroom: Dynamic Geometry Systems as Tools of Semiotic Mediation

ERIC Educational Resources Information Center

Mariotti, Maria Alessandra

2012-01-01

The objective of this paper is to discuss the didactic potential offered by the use of a Dynamic Geometry System (DGS) in introducing students to theoretical thinking and specifically to the practice of proof. Starting from a discussion about what constitutes the general objective in developing students' sense of proof, the notion of Theorem is…

Alternative Theoretical Bases for the Study of Human Communication: The Systems Perspective.

ERIC Educational Resources Information Center

Monge, Peter R.

Three potentially useful perspectives for the scientific development of human communication theory are the law model, the systems approach, and the rules paradigm. It is the purpose of this paper to indicate the utility of the systems approach. The first section of this paper provides a brief account of the systems view of the world. Outlined in…

The ReaxFF reactive force-field: Development, applications, and future directions

DOE PAGES

Senftle, Thomas; Hong, Sungwook; Islam, Md Mahbubul; ...

2016-03-04

The reactive force-field (ReaxFF) interatomic potential is a powerful computational tool for exploring, developing and optimizing material properties. Methods based on the principles of quantum mechanics (QM), while offering valuable theoretical guidance at the electronic level, are often too computationally intense for simulations that consider the full dynamic evolution of a system. Alternatively, empirical interatomic potentials that are based on classical principles require significantly fewer computational resources, which enables simulations to better describe dynamic processes over longer timeframes and on larger scales. Such methods, however, typically require a predefined connectivity between atoms, precluding simulations that involve reactive events. The ReaxFFmore » method was developed to help bridge this gap. Approaching the gap from the classical side, ReaxFF casts the empirical interatomic potential within a bond-order formalism, thus implicitly describing chemical bonding without expensive QM calculations. As a result, this article provides an overview of the development, application, and future directions of the ReaxFF method.« less

Wideband optical sensing using pulse interferometry.

PubMed

Rosenthal, Amir; Razansky, Daniel; Ntziachristos, Vasilis

2012-08-13

Advances in fabrication of high-finesse optical resonators hold promise for the development of miniaturized, ultra-sensitive, wide-band optical sensors, based on resonance-shift detection. Many potential applications are foreseen for such sensors, among them highly sensitive detection in ultrasound and optoacoustic imaging. Traditionally, sensor interrogation is performed by tuning a narrow linewidth laser to the resonance wavelength. Despite the ubiquity of this method, its use has been mostly limited to lab conditions due to its vulnerability to environmental factors and the difficulty of multiplexing - a key factor in imaging applications. In this paper, we develop a new optical-resonator interrogation scheme based on wideband pulse interferometry, potentially capable of achieving high stability against environmental conditions without compromising sensitivity. Additionally, the method can enable multiplexing several sensors. The unique properties of the pulse-interferometry interrogation approach are studied theoretically and experimentally. Methods for noise reduction in the proposed scheme are presented and experimentally demonstrated, while the overall performance is validated for broadband optical detection of ultrasonic fields. The achieved sensitivity is equivalent to the theoretical limit of a 6 MHz narrow-line width laser, which is 40 times higher than what can be usually achieved by incoherent interferometry for the same optical resonator.

Field gradients can control the alignment of nanorods.

PubMed

Ooi, Chinchun; Yellen, Benjamin B

2008-08-19

This work is motivated by the unexpected experimental observation that field gradients can control the alignment of nonmagnetic nanorods immersed inside magnetic fluids. In the presence of local field gradients, nanorods were observed to align perpendicular to the external field at low field strengths, but parallel to the external field at high field strengths. The switching behavior results from the competition between a preference to align with the external field (orientational potential energy) and preference to move into regions of minimum magnetic field (positional potential energy). A theoretical model is developed to explain this experimental behavior by investigating the statistics of nanorod alignment as a function of both the external uniform magnetic field strength and the local magnetic field variation above a periodic array of micromagnets. Computational phase diagrams are developed which indicate that the relative population of nanorods in parallel and perpendicular states can be adjusted through several control parameters. However, an energy barrier to rotation was discovered to influence the rate kinetics and restrict the utility of this assembly technique to nanorods which are slightly shorter than the micromagnet length. Experimental results concerning the orientation of nanorods inside magnetic fluid are also presented and shown to be in strong agreement with the theoretical work.

Theoretical analysis of degradation mechanisms in the formation of morphogen gradients

NASA Astrophysics Data System (ADS)

Bozorgui, Behnaz; Teimouri, Hamid; Kolomeisky, Anatoly B.

2015-07-01

Fundamental biological processes of development of tissues and organs in multicellular organisms are governed by various signaling molecules, which are called morphogens. It is known that spatial and temporal variations in the concentration profiles of signaling molecules, which are frequently referred as morphogen gradients, lead to a cell differentiation via activating specific genes in a concentration-dependent manner. It is widely accepted that the establishment of the morphogen gradients involves multiple biochemical reactions and diffusion processes. One of the critical elements in the formation of morphogen gradients is a degradation of signaling molecules. We develop a new theoretical approach that provides a comprehensive description of the degradation mechanisms. It is based on the idea that the degradation works as an effective potential that drives the signaling molecules away from the source region. Utilizing the method of first-passage processes, the dynamics of the formation of morphogen gradients for various degradation mechanisms is explicitly evaluated. It is found that linear degradation processes lead to a dynamic behavior specified by times to form the morphogen gradients that depend linearly on the distance from the source. This is because the effective potential due to the degradation is quite strong. At the same time, nonlinear degradation mechanisms yield a quadratic scaling in the morphogen gradients formation times since the effective potentials are much weaker. Physical-chemical explanations of these phenomena are presented.

Principles and performance of tapered fiber lasers: from uniform to flared geometry.

PubMed

Kerttula, Juho; Filippov, Valery; Chamorovskii, Yuri; Ustimchik, Vasily; Golant, Konstantin; Okhotnikov, Oleg G

2012-10-10

We have studied the recently demonstrated concept of fiber lasers based on active tapered double-clad fiber (T-DCF) in copropagating and counterpropagating configurations, both theoretically and experimentally, and compared the performance to fiber lasers based on conventional cylindrical fibers in end-pumped configurations. Specific properties of T-DCFs were considered theoretically using a rate-equation model developed for tapered fibers, and a detailed comparative study was carried out experimentally. Furthermore, we have studied mode coupling effects in long adiabatic tapers due to coiling and local bending. The results allow us to conclude that, with proper fiber design, the T-DCF technology offers a high-potential alternative for bright, cost-effective fiber devices.

Developing a theoretical framework for complex community-based interventions.

PubMed

Angeles, Ricardo N; Dolovich, Lisa; Kaczorowski, Janusz; Thabane, Lehana

2014-01-01

Applying existing theories to research, in the form of a theoretical framework, is necessary to advance knowledge from what is already known toward the next steps to be taken. This article proposes a guide on how to develop a theoretical framework for complex community-based interventions using the Cardiovascular Health Awareness Program as an example. Developing a theoretical framework starts with identifying the intervention's essential elements. Subsequent steps include the following: (a) identifying and defining the different variables (independent, dependent, mediating/intervening, moderating, and control); (b) postulating mechanisms how the independent variables will lead to the dependent variables; (c) identifying existing theoretical models supporting the theoretical framework under development; (d) scripting the theoretical framework into a figure or sets of statements as a series of hypotheses, if/then logic statements, or a visual model; (e) content and face validation of the theoretical framework; and (f) revising the theoretical framework. In our example, we combined the "diffusion of innovation theory" and the "health belief model" to develop our framework. Using the Cardiovascular Health Awareness Program as the model, we demonstrated a stepwise process of developing a theoretical framework. The challenges encountered are described, and an overview of the strategies employed to overcome these challenges is presented.

Metasynthesis findings: potential versus reality.

PubMed

Finfgeld-Connett, Deborah

2014-11-01

Early on, qualitative researchers predicted that metasynthesis research had the potential to significantly push knowledge development forward. More recently, scholars have questioned whether this is actually occurring. To examine this concern, a randomly selected sample of metasynthesis articles was systematically reviewed to identify the types of findings that have been produced. Based on this systematic examination, it appears that findings from metasynthesis investigations might not be reaching their full potential. Metasynthesis investigations frequently result in isolated findings rather than findings in relationship, and opportunities to generate research hypotheses and theoretical models are not always fully realized. With this in mind, methods for moving metasynthesis findings into relationship are discussed. © The Author(s) 2014.

Methodology for vocational psychodiagnostics of senior schoolchildren using information technologies

NASA Astrophysics Data System (ADS)

Bogdanovskaya, I. M.; Kosheleva, A. N.; Kiselev, P. B.; Davydova, Yu. A.

2017-01-01

The article identifies the role and main problems of vocational psychodiagnostics in modern socio-cultural conditions. It analyzes the potentials of information technologies in vocational psychodiagnostics of senior schoolchildren. The article describes the theoretical and methodological grounds, content and diagnostic potentials of the computerized method in vocational psychodiagnostics. The computerized method includes three blocks of sub-tests to identify intellectual potential, personal qualities, professional interests and values, career orientations, as well as subtests to analyze the specific life experience of senior schoolchildren. The results of diagnostics allow developing an integrated psychodiagnostic conclusion with recommendations. The article contains options of software architecture for the given method.

Interferometry of Klein tunnelling electrons in graphene quantum rings

NASA Astrophysics Data System (ADS)

de Sousa, D. J. P.; Chaves, Andrey; Pereira, J. M.; Farias, G. A.

2017-01-01

We theoretically study a current switch that exploits the phase acquired by a charge carrier as it tunnels through a potential barrier in graphene. The system acts as an interferometer based on an armchair graphene quantum ring, where the phase difference between interfering electronic wave functions for each path can be controlled by tuning either the height or the width of a potential barrier in the ring arms. By varying the parameters of the potential barriers, the interference can become completely destructive. We demonstrate how this interference effect can be used for developing a simple graphene-based logic gate with a high on/off ratio.

Review of the potential of silanes as rocket/scramjet fuels

NASA Astrophysics Data System (ADS)

Hidding, Bernhard; Pfitzner, Michael; Simone, Domenico; Bruno, Claudio

2008-07-01

Experimental use as well as theoretical considerations regarding silanes as fuels for spacecrafts and supersonic flight are reviewed. The historical circumstances leading to the utilization of monosilane as a fuel additive for scramjets are highlighted and milestones in the chemical research on silanes are summarized. Recent developments such as the use of monosilane as an ignition aid in the NASA X-43A scramjet flights as well as general progress in silicon hydride research, including liquid higher silanes and the resulting potential for the propulsion field are discussed.

Theory of viscous transonic flow over airfoils at high Reynolds number

NASA Technical Reports Server (NTRS)

Melnik, R. E.; Chow, R.; Mead, H. R.

1977-01-01

This paper considers viscous flows with unseparated turbulent boundary layers over two-dimensional airfoils at transonic speeds. Conventional theoretical methods are based on boundary layer formulations which do not account for the effect of the curved wake and static pressure variations across the boundary layer in the trailing edge region. In this investigation an extended viscous theory is developed that accounts for both effects. The theory is based on a rational analysis of the strong turbulent interaction at airfoil trailing edges. The method of matched asymptotic expansions is employed to develop formal series solutions of the full Reynolds equations in the limit of Reynolds numbers tending to infinity. Procedures are developed for combining the local trailing edge solution with numerical methods for solving the full potential flow and boundary layer equations. Theoretical results indicate that conventional boundary layer methods account for only about 50% of the viscous effect on lift, the remaining contribution arising from wake curvature and normal pressure gradient effects.

Toward systematic integration between self-determination theory and motivational interviewing as examples of top-down and bottom-up intervention development: autonomy or volition as a fundamental theoretical principle

PubMed Central

2012-01-01

Clinical interventions can be developed through two distinct pathways. In the first, which we call top-down, a well-articulated theory drives the development of the intervention, whereas in the case of a bottom-up approach, clinical experience, more so than a dedicated theoretical perspective, drives the intervention. Using this dialectic, this paper discusses Self-Determination Theory (SDT) [1,2] and Motivational Interviewing (MI) [3] as prototypical examples of a top-down and bottom-up approaches, respectively. We sketch the different starting points, foci and developmental processes of SDT and MI, but equally note the complementary character and the potential for systematic integration between both approaches. Nevertheless, for a deeper integration to take place, we contend that MI researchers might want to embrace autonomy as a fundamental basic process underlying therapeutic change and we discuss the advantages of doing so. PMID:22385828

Assessment of Environmental Enteropathy in the MAL-ED Cohort Study: Theoretical and Analytic Framework

PubMed Central

Kosek, Margaret; Guerrant, Richard L.; Kang, Gagandeep; Bhutta, Zulfiqar; Yori, Pablo Peñataro; Gratz, Jean; Gottlieb, Michael; Lang, Dennis; Lee, Gwenyth; Haque, Rashidul; Mason, Carl J.; Ahmed, Tahmeed; Lima, Aldo; Petri, William A.; Houpt, Eric; Olortegui, Maribel Paredes; Seidman, Jessica C.; Mduma, Estomih; Samie, Amidou; Babji, Sudhir

2014-01-01

Individuals in the developing world live in conditions of intense exposure to enteric pathogens due to suboptimal water and sanitation. These environmental conditions lead to alterations in intestinal structure, function, and local and systemic immune activation that are collectively referred to as environmental enteropathy (EE). This condition, although poorly defined, is likely to be exacerbated by undernutrition as well as being responsible for permanent growth deficits acquired in early childhood, vaccine failure, and loss of human potential. This article addresses the underlying theoretical and analytical frameworks informing the methodology proposed by the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) cohort study to define and quantify the burden of disease caused by EE within a multisite cohort. Additionally, we will discuss efforts to improve, standardize, and harmonize laboratory practices within the MAL-ED Network. These efforts will address current limitations in the understanding of EE and its burden on children in the developing world. PMID:25305293

Progress and Prospects for Stem Cell Engineering

PubMed Central

Ashton, Randolph S.; Keung, Albert J.; Peltier, Joseph; Schaffer, David V.

2018-01-01

Stem cells offer tremendous biomedical potential owing to their abilities to self-renew and differentiate into cell types of multiple adult tissues. Researchers and engineers have increasingly developed novel discovery technologies, theoretical approaches, and cell culture systems to investigate microenvironmental cues and cellular signaling events that control stem cell fate. Many of these technologies facilitate high-throughput investigation of microenvironmental signals and the intracellular signaling networks and machinery processing those signals into cell fate decisions. As our aggregate empirical knowledge of stem cell regulation grows, theoretical modeling with systems and computational biology methods has and will continue to be important for developing our ability to analyze and extract important conceptual features of stem cell regulation from complex data. Based on this body of knowledge, stem cell engineers will continue to develop technologies that predictably control stem cell fate with the ultimate goal of being able to accurately and economically scale up these systems for clinical-grade production of stem cell therapeutics. PMID:22432628

Measurement of characteristics of lightning at high altitudes

NASA Technical Reports Server (NTRS)

Coquelet, M.; Gall, D.

1981-01-01

New development in aeronautical technology -- the use of composite materials, new electronic components, electric flight controls -- have made aircraft potentially more and more vulnerable to the effects of lightning. In-flight tests were conducted to evaluate the current in a bolt of lightning, to measure voltage surge in the onboard circuitry and in certain pieces of equipment, and to document the relationship lightning bolt current and the voltage surge so as to develop a theoretical model and thuds to become acquainted with the significant

Aluminum as anode for energy storage and conversion: a review

NASA Astrophysics Data System (ADS)

Li, Qingfeng; Bjerrum, Niels J.

Aluminum has long attracted attention as a potential battery anode because of its high theoretical voltage and specific energy. The protective oxide layer on the aluminum surface is however detrimental to the battery performance, contributing to failure to achieve the reversible potential and causing the delayed activation of the anode. By developing aluminum alloys as anodes and solution additives to electrolytes, a variety of aluminum batteries have been extensively investigated for various applications. From molten salt and other non-aqueous electrolytes, aluminum can be electrodeposited and therefore be suitable for developing rechargable batteries. Considerable efforts have been made to develop secondary aluminum batteries of high power density. In the present paper, these research activities are reviewed, including aqueous electrolyte primary batteries, aluminum-air batteries and molten salt secondary batteries.

Central gender theoretical concepts in health research: the state of the art.

PubMed

Hammarström, Anne; Johansson, Klara; Annandale, Ellen; Ahlgren, Christina; Aléx, Lena; Christianson, Monica; Elwér, Sofia; Eriksson, Carola; Fjellman-Wiklund, Anncristine; Gilenstam, Kajsa; Gustafsson, Per E; Harryson, Lisa; Lehti, Arja; Stenberg, Gunilla; Verdonk, Petra

2014-02-01

Despite increasing awareness of the importance of gender perspectives in health science, there is conceptual confusion regarding the meaning and the use of central gender theoretical concepts. We argue that it is essential to clarify how central concepts are used within gender theory and how to apply them to health research. We identify six gender theoretical concepts as central and interlinked-but problematic and ambiguous in health science: sex, gender, intersectionality, embodiment, gender equity and gender equality. Our recommendations are that: the concepts sex and gender can benefit from a gender relational theoretical approach (i.e., a focus on social processes and structures) but with additional attention to the interrelations between sex and gender; intersectionality should go beyond additive analyses to study complex intersections between the major factors which potentially influence health and ensure that gendered power relations and social context are included; we need to be aware of the various meanings given to embodiment, which achieve an integration of gender and health and attend to different levels of analyses to varying degrees; and appreciate that gender equality concerns absence of discrimination between women and men while gender equity focuses on women's and men's health needs, whether similar or different. We conclude that there is a constant need to justify and clarify our use of these concepts in order to advance gender theoretical development. Our analysis is an invitation for dialogue but also a call to make more effective use of the knowledge base which has already developed among gender theorists in health sciences in the manner proposed in this paper.

Molecular dynamics simulations for mechanical properties of borophene: parameterization of valence force field model and Stillinger-Weber potential

PubMed Central

Zhou, Yu-Ping; Jiang, Jin-Wu

2017-01-01

While most existing theoretical studies on the borophene are based on first-principles calculations, the present work presents molecular dynamics simulations for the lattice dynamical and mechanical properties in borophene. The obtained mechanical quantities are in good agreement with previous first-principles calculations. The key ingredients for these molecular dynamics simulations are the two efficient empirical potentials developed in the present work for the interaction of borophene with low-energy triangular structure. The first one is the valence force field model, which is developed with the assistance of the phonon dispersion of borophene. The valence force field model is a linear potential, so it is rather efficient for the calculation of linear quantities in borophene. The second one is the Stillinger-Weber potential, whose parameters are derived based on the valence force field model. The Stillinger-Weber potential is applicable in molecular dynamics simulations of nonlinear physical or mechanical quantities in borophene. PMID:28349983

Limits to biofuels

NASA Astrophysics Data System (ADS)

Johansson, S.

2013-06-01

Biofuel production is dependent upon agriculture and forestry systems, and the expectations of future biofuel potential are high. A study of the global food production and biofuel production from edible crops implies that biofuel produced from edible parts of crops lead to a global deficit of food. This is rather well known, which is why there is a strong urge to develop biofuel systems that make use of residues or products from forest to eliminate competition with food production. However, biofuel from agro-residues still depend upon the crop production system, and there are many parameters to deal with in order to investigate the sustainability of biofuel production. There is a theoretical limit to how much biofuel can be achieved globally from agro-residues and this amounts to approximately one third of todays' use of fossil fuels in the transport sector. In reality this theoretical potential may be eliminated by the energy use in the biomass-conversion technologies and production systems, depending on what type of assessment method is used. By surveying existing studies on biofuel conversion the theoretical limit of biofuels from 2010 years' agricultural production was found to be either non-existent due to energy consumption in the conversion process, or up to 2-6000TWh (biogas from residues and waste and ethanol from woody biomass) in the more optimistic cases.

Life cycle assessment of pyrolysis, gasification and incineration waste-to-energy technologies: Theoretical analysis and case study of commercial plants.

PubMed

Dong, Jun; Tang, Yuanjun; Nzihou, Ange; Chi, Yong; Weiss-Hortala, Elsa; Ni, Mingjiang

2018-06-01

Municipal solid waste (MSW) pyrolysis and gasification are in development, stimulated by a more sustainable waste-to-energy (WtE) option. Since comprehensive comparisons of the existing WtE technologies are fairly rare, this study aims to conduct a life cycle assessment (LCA) using two sets of data: theoretical analysis, and case studies of large-scale commercial plants. Seven systems involving thermal conversion (pyrolysis, gasification, incineration) and energy utilization (steam cycle, gas turbine/combined cycle, internal combustion engine) are modeled. Theoretical analysis results show that pyrolysis and gasification, in particular coupled with a gas turbine/combined cycle, have the potential to lessen the environmental loadings. The benefits derive from an improved energy efficiency leading to less fossil-based energy consumption, and the reduced process emissions by syngas combustion. Comparison among the four operating plants (incineration, pyrolysis, gasification, gasification-melting) confirms a preferable performance of the gasification plant attributed to syngas cleaning. The modern incineration is superior over pyrolysis and gasification-melting at present, due to the effectiveness of modern flue gas cleaning, use of combined heat and power (CHP) cycle, and ash recycling. The sensitivity analysis highlights a crucial role of the plant efficiency and pyrolysis char land utilization. The study indicates that the heterogeneity of MSW and syngas purification technologies are the most relevant impediments for the current pyrolysis/gasification-based WtE. Potential development should incorporate into all process aspects to boost the energy efficiency, improve incoming waste quality, and achieve efficient residues management. Copyright © 2018 Elsevier B.V. All rights reserved.

Building child trauma theory from longitudinal studies: a meta-analysis.

PubMed

Alisic, Eva; Jongmans, Marian J; van Wesel, Floryt; Kleber, Rolf J

2011-07-01

Many children are exposed to traumatic events, with potentially serious psychological and developmental consequences. Therefore, understanding development of long-term posttraumatic stress in children is essential. We aimed to contribute to child trauma theory by focusing on theory use and theory validation in longitudinal studies. Forty studies measuring short-term predictors and long-term posttraumatic stress symptoms were identified and coded for theoretical grounding, sample characteristics, and correlational effect sizes. Explicit theoretical frameworks were present in a minority of the studies. Important predictors of long-term posttraumatic stress were symptoms of acute and short-term posttraumatic stress, depression, anxiety, and parental posttraumatic stress. Female gender, injury severity, duration of hospitalization, and elevated heart rate shortly after hospitalization yielded small effect sizes. Age, minority status, and socioeconomic status were not significantly related to long-term posttraumatic stress reactions. Since many other variables were not studied frequently enough to compute effect sizes, existing theoretical frameworks could only be partially confirmed or falsified. Child trauma theory-building can be facilitated by development of encouraging journal policies, the use of comparable methods, and more intense collaboration. Copyright © 2011 Elsevier Ltd. All rights reserved.

Psychological theory and pedagogical effectiveness: the learning promotion potential framework.

PubMed

Tomlinson, Peter

2008-12-01

After a century of educational psychology, eminent commentators are still lamenting problems besetting the appropriate relating of psychological insights to teaching design, a situation not helped by the persistence of crude assumptions concerning the nature of pedagogical effectiveness. To propose an analytical or meta-theoretical framework based on the concept of learning promotion potential (LPP) as a basis for understanding the basic relationship between psychological insights and teaching strategies, and to draw out implications for psychology-based pedagogical design, development and research. This is a theoretical and meta-theoretical paper relying mainly on conceptual analysis, though also calling on psychological theory and research. Since teaching consists essentially in activity designed to promote learning, it follows that a teaching strategy has the potential in principle to achieve particular kinds of learning gains (LPP) to the extent that it embodies or stimulates the relevant learning processes on the part of learners and enables the teacher's functions of on-line monitoring and assistance for such learning processes. Whether a teaching strategy actually does realize its LPP by way of achieving its intended learning goals depends also on the quality of its implementation, in conjunction with other factors in the situated interaction that teaching always involves. The core role of psychology is to provide well-grounded indication of the nature of such learning processes and the teaching functions that support them, rather than to directly generate particular ways of teaching. A critically eclectic stance towards potential sources of psychological insight is argued for. Applying this framework, the paper proposes five kinds of issue to be attended to in the design and evaluation of psychology-based pedagogy. Other work proposing comparable ideas is briefly reviewed, with particular attention to similarities and a key difference with the ideas of Oser and Baeriswyl (2001).

Variation and adaptation: learning from success in patient safety-oriented simulation training.

PubMed

Dieckmann, Peter; Patterson, Mary; Lahlou, Saadi; Mesman, Jessica; Nyström, Patrik; Krage, Ralf

2017-01-01

Simulation is traditionally used to reduce errors and their negative consequences. But according to modern safety theories, this focus overlooks the learning potential of the positive performance, which is much more common than errors. Therefore, a supplementary approach to simulation is needed to unfold its full potential. In our commentary, we describe the learning from success (LFS) approach to simulation and debriefing. Drawing on several theoretical frameworks, we suggest supplementing the widespread deficit-oriented, corrective approach to simulation with an approach that focusses on systematically understanding how good performance is produced in frequent (mundane) simulation scenarios. We advocate to investigate and optimize human activity based on the connected layers of any setting: the embodied competences of the healthcare professionals, the social and organizational rules that guide their actions, and the material aspects of the setting. We discuss implications of these theoretical perspectives for the design and conduct of simulation scenarios, post-simulation debriefings, and faculty development programs.

Energetics of protein-DNA interactions.

PubMed

Donald, Jason E; Chen, William W; Shakhnovich, Eugene I

2007-01-01

Protein-DNA interactions are vital for many processes in living cells, especially transcriptional regulation and DNA modification. To further our understanding of these important processes on the microscopic level, it is necessary that theoretical models describe the macromolecular interaction energetics accurately. While several methods have been proposed, there has not been a careful comparison of how well the different methods are able to predict biologically important quantities such as the correct DNA binding sequence, total binding free energy and free energy changes caused by DNA mutation. In addition to carrying out the comparison, we present two important theoretical models developed initially in protein folding that have not yet been tried on protein-DNA interactions. In the process, we find that the results of these knowledge-based potentials show a strong dependence on the interaction distance and the derivation method. Finally, we present a knowledge-based potential that gives comparable or superior results to the best of the other methods, including the molecular mechanics force field AMBER99.

Mixed quantum-classical simulation of the hydride transfer reaction catalyzed by dihydrofolate reductase based on a mapped system-harmonic bath model

NASA Astrophysics Data System (ADS)

Xu, Yang; Song, Kai; Shi, Qiang

2018-03-01

The hydride transfer reaction catalyzed by dihydrofolate reductase is studied using a recently developed mixed quantum-classical method to investigate the nuclear quantum effects on the reaction. Molecular dynamics simulation is first performed based on a two-state empirical valence bond potential to map the atomistic model to an effective double-well potential coupled to a harmonic bath. In the mixed quantum-classical simulation, the hydride degree of freedom is quantized, and the effective harmonic oscillator modes are treated classically. It is shown that the hydride transfer reaction rate using the mapped effective double-well/harmonic-bath model is dominated by the contribution from the ground vibrational state. Further comparison with the adiabatic reaction rate constant based on the Kramers theory confirms that the reaction is primarily vibrationally adiabatic, which agrees well with the high transmission coefficients found in previous theoretical studies. The calculated kinetic isotope effect is also consistent with the experimental and recent theoretical results.

Extension of the quasistatic far-wing line shape theory to multicomponent anisotropic potentials

NASA Technical Reports Server (NTRS)

Ma, Q.; Tipping, R. H.

1994-01-01

The formalism developed previously for the calculation of the far-wing line shape function and the corresponding absorption coefficient using a single-component anisotropic interaction term and the binary collision and quasistatic approximations is generalized to multicomponent anisotropic potential functions. Explicit expressions are presented for several common cases, including the long-range dipole-dipole plus dipole-quadrupole interaction and a linear molecule interacting with a perturber atom. After determining the multicomponent functional representation for the interaction between the CO2 and Ar from previously published data, we calculate the theoretical line shape function and the corresponding absorption due to the nu(sub 3) band of CO2 in the frequency range 2400-2580 cm(exp -1) and compare our results with previous calculations carried out using a single-component anisotropic interaction, and with the results obtained assuming Lorentzian line shapes. The principal uncertainties in the present results, possible refinements of the theoretical formalism, and the applicability to other systems are discussed briefly.

The onset of plasma potential locking

DOE PAGES

Hopkins, Matthew M.; Yee, Benjamin T.; Baalrud, Scott D.; ...

2016-06-22

In this study, we provide insight into the role and impact that a positively biased electrode (anode) has on bulk plasma potential. Using two-dimensional Particle-in-Cell simulations, we investigate the plasma potential as an anode transitions from very small (“probe” mode) to large (“locking” mode). Prior theory provides some guidance on when and how this transition takes place. Initial experimental results are also compared. The simulations demonstrate that as the surface area of the anode is increased transitions in plasma potential and sheath polarity occur, consistent with experimental observations and theoretical predictions. It is expected that understanding this basic plasma behaviormore » will be of interest to basic plasma physics communities, diagnostic developers, and plasma processing devices where control of bulk plasma potential is important.« less

Stem-cell-derived products: an FDA update.

PubMed

Moos, Malcolm

2008-12-01

The therapeutic potential of products derived from stem cells of various types has prompted increasing research and development and public attention. Initiation of human clinical trials in the not-too-distant future is now a realistic possibility. It is, therefore, important to weigh the potential benefits against known, theoretical and totally unsuspected risks in light of current knowledge to ensure that subjects participating in these trials are afforded the most reasonable balance possible between potential risks and potential benefits. There are no apparent differences in fundamental, qualitative biological characteristics between stem-cell-derived products and other cellular therapies regulated by the United States Food and Drug Administration (FDA). Existing authorities can, therefore, be applied. Nevertheless, these products do have properties that require careful evaluation.

A Theoretical Search for Supervelocity Semiconductors

DTIC Science & Technology

1992-10-01

interfaces, doping control and compositional uniformity with atomic level dimensions. The development of ALE may very well prove to be the ultimate growth...pseudomorphic or strained-layer devices. These structures permit extended compositional ranges and, thus, have a number of potential advantages such as...in silicon devices For the past fifteen years, the silicon MOSFET industry has been dealing increasingly with prob- lems related to hot electron

Variational Approach in the Theory of Liquid-Crystal State

NASA Astrophysics Data System (ADS)

Gevorkyan, E. V.

2018-03-01

The variational calculus by Leonhard Euler is the basis for modern mathematics and theoretical physics. The efficiency of variational approach in statistical theory of liquid-crystal state and in general case in condensed state theory is shown. The developed approach in particular allows us to introduce correctly effective pair interactions and optimize the simple models of liquid crystals with help of realistic intermolecular potentials.

Support of research in X-ray astronomy

NASA Technical Reports Server (NTRS)

Garmire, G.

1983-01-01

Activities described include: (1) the evaluation of CCD detectors for X-ray astronomy applications; (2) contributions to the development of an imaging gas scintillation proportional counter; (3) the evaluation of certain metal oxide crystals as potential radiation detectors; (4) optical observations and searches for X-ray sources discovered by the HEAO-1 A2 experiment; and (5) theoretical modeling of nonequilibrium ionization structure of supernova remnants.

The Importance of Morphemic Awareness to Reading Achievement and the Potential of Signing Morphemes to Supporting Reading Development

ERIC Educational Resources Information Center

Nielsen, Diane Corcoran; Luetke, Barbara; Stryker, Deborah S.

2011-01-01

The ability to access and understand the meaning of multi-morphemic words is essential for age-appropriate literacy growth as well as for achievement in other participants, such as science and social studies, which are so print-dependent. This paper provides a theoretical basis for focusing on the morphology of English when teaching students who…

Screen Worlds, Sound Worlds and School: A Consideration of the Potential of the Ethnomusicology of Australian Indigenous Film for Music Education

ERIC Educational Resources Information Center

Webb, Michael; Fienberg, Thomas

2011-01-01

This article arises from the authors' belief that there is a need to develop motivating ways for students across Australia to meaningfully encounter Australian indigenous music, the breadth and richness of which is beginning to be conveyed via a diverse range of mainstream media texts. Engaging with theoretical insights from the ethnomusicology of…

Trust, Responsiveness and Communities of Care: An Ethnographic Study of the Significance and Development of Parent-Caregiver Relationships in Irish Early Years Settings

ERIC Educational Resources Information Center

Garrity, Sheila; Canavan, John

2017-01-01

Conceptualising early years settings as "communities of care" reflects the narrative arising from recent ethnographic research conducted in the West and Midlands areas of Ireland. Drawing on the ethic of care as an underpinning theoretical framework, this article outlines the potential of early years settings to represent reliable,…

Single particle and collective behavior of electrons in a diamagnetic Kepler trap

NASA Astrophysics Data System (ADS)

Godino, Joseph L.

2001-10-01

The Diamagnetic Kepler Trap (DKT) is a potential energy well that arises from a static Coulomb potential in a superimposed uniform magnetic field. Our goal is to study the single particle and collective behavior of electrons in a DKT. We have three principal reasons for doing so. First, trajectories of a single electron in a DKT can exhibit chaotic motion. The transition from regular to chaotic motion is theoretically interesting and we want to understand how this occurs. Second, we want to understand the behavior of a system of electrons in a laboratory realization of a DKT. In this situation, we have a many particle system of electrons and ions that move under the influence of external potentials in a neutral background gas. Under these conditions, trapped electrons exhibit collective modes of oscillation. Finally, by understanding the behavior of the trapped electrons we believe that we may be able to develop the DKT into an ion beam source. Due to the complexity of the DKT, we break our investigation into three parts. First, we conduct a theoretical and computational study of the motion of a single electron in a DKT. To enhance our understanding, we develop a simple model of the DKT that retains the significant properties of the exact system while permitting us to go further with our theoretical analysis. We develop a solution to the model equations of motion, which provide us with additional insight into the behavior of trajectories near the chaotic transition. Second, we characterize the behavior of trapped electrons in our experimental DKT. We present a set of measurements showing the collective oscillations. In addition, when we operate the DKT at magnetic fields greater than 100 gauss, we observe a columnar plasma beam emerging from the trap that we also characterize. Finally, we simulate the dynamics of the electrons and ions in a DKT. Here we include their interactions with the neutral background gas, boundary effects and space charge. We use the information obtained from our simulations to enhance our knowledge of the electrons in the experimental system.

Climatic Change, Conflict and Peace in Transboundary River Basins - A Theoretical Perspective

NASA Astrophysics Data System (ADS)

Siegfried, T. U.; Beck, L.; Koubi, V.; Bernauer, T.

2011-12-01

Recent research shows that one of the most significant risk for societal development pertains to water availability and that the greatest risks for unrest stemming from economic deprivation and the erosion of livelihoods is found in transboundary river basins in poor and politically unstable parts of the world. While until now, historic linkages between water scarcity and conflict were weak at best, there is growing fear that environmental change will increasingly lead to an entanglement of conflict and resources dynamics in the future. Where resources are not jointly managed in a cooperative way and resources sharing mechanisms not legislated by sound international institutions and were significant impacts from environmental change are expected, these developments give rise to concern. To study environmental change and conflict interlinkages, we develop a formal hydro-climatological model for transboundary freshwater resources and investigate theoretically how climate change translates into potential for conflict and peace, contingent on configurations of power between riparians. The model accounts for how upstream countries exercise power by using water whereas downstream countries use power to obtain water. We show that equilibrium water allocation outcomes are biased towards the more powerful riparian, and that absolute upstream or downstream river basin dominance are limiting cases of our general model. Our model suggests that the basin-wide conflict potential is always more sensitive to changes in relative power between riparian states than to impacts from climatic changes.

Neurotech for Neuroscience: Unifying Concepts, Organizing Principles, and Emerging Tools

PubMed Central

Silver, Rae; Boahen, Kwabena; Grillner, Sten; Kopell, Nancy; Olsen, Kathie L.

2012-01-01

The ability to tackle analysis of the brain at multiple levels simultaneously is emerging from rapid methodological developments. The classical research strategies of “measure,” “model,” and “make” are being applied to the exploration of nervous system function. These include novel conceptual and theoretical approaches, creative use of mathematical modeling, and attempts to build brain-like devices and systems, as well as other developments including instrumentation and statistical modeling (not covered here). Increasingly, these efforts require teams of scientists from a variety of traditional scientific disciplines to work together. The potential of such efforts for understanding directed motor movement, emergence of cognitive function from neuronal activity, and development of neuromimetic computers are described by a team that includes individuals experienced in behavior and neuroscience, mathematics, and engineering. Funding agencies, including the National Science Foundation, explore the potential of these changing frontiers of research for developing research policies and long-term planning. PMID:17978017

Mathematics teacher professional development in and through internet use: reflections on an ethnographic study

NASA Astrophysics Data System (ADS)

Patahuddin, Sitti Maesuri

2013-12-01

This paper is a reflection on a model for mathematics teacher professional development with respect to technology. The model was informed by three interrelated concepts: (1) a theory of teacher professional development from analysis of the field, (2) the zone theory of teacher professional learning, and (3) ethnography as a method. The model was applied in a study that focused on the uses of the Internet for primary mathematics teacher professional development, particularly to exploit the potential of the Internet for professional learning and to use it in professional work. This is illustrated through selected critical events over an eight-month ethnographic intervention in a primary mathematics classroom in Australia. Though the model is theoretically grounded, it opens up questions about the power, potential, and challenges as well as its feasibility, with respect to not only the teacher but also the ethnographer.

Predicting Child Abuse Potential: An Empirical Investigation of Two Theoretical Frameworks

ERIC Educational Resources Information Center

Begle, Angela Moreland; Dumas, Jean E.; Hanson, Rochelle F.

2010-01-01

This study investigated two theoretical risk models predicting child maltreatment potential: (a) Belsky's (1993) developmental-ecological model and (b) the cumulative risk model in a sample of 610 caregivers (49% African American, 46% European American; 53% single) with a child between 3 and 6 years old. Results extend the literature by using a…

S-factor for radiative capture reactions for light nuclei at astrophysical energies

NASA Astrophysics Data System (ADS)

Ghasemi, Reza; Sadeghi, Hossein

2018-06-01

The astrophysical S-factors of thermonuclear reactions, including radiative capture reactions and their analysis in the frame of different theoretical models, are the main source of nuclear processes. We have done research on the radiative capture reactions importance in the framework of a potential model. Investigation of the reactions in the astrophysical energies is of great interest in the aspect of astrophysics and nuclear physics for developing correct models of burning and evolution of stars. The experimental measurements are very difficult and impossible because of these reactions occurrence at low-energies. In this paper we do a calculation on radiative capture astrophysical S-factors for nuclei in the mass region A < 17. We calculate the astrophysical factor for the dipole electronic transition E1 and magnetic dipole transition M1 and electric quadrupole transition E2 by using the M3Y potential for non-resonances and resonances captures. Then we have got the parameter of a central part and spin-orbit part of M3Y potential and spectroscopic factor for reaction channels. For the astrophysical S-factor of this article the good agreement is achieved In comparison with experimental data and other theoretical methods.

Computational crystallization.

PubMed

Altan, Irem; Charbonneau, Patrick; Snell, Edward H

2016-07-15

Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

Recreational 3,4-methylenedioxymethamphetamine or 'ecstasy': Current perspective and future research prospects.

PubMed

Parrott, Andrew C; Downey, Luke A; Roberts, Carl A; Montgomery, Cathy; Bruno, Raimondo; Fox, Helen C

2017-08-01

The purpose of this article is to debate current understandings about the psychobiological effects of recreational 3,4-methylenedioxymethamphetamine (MDMA or 'ecstasy'), and recommend theoretically-driven topics for future research. Recent empirical findings, especially those from novel topic areas were reviewed. Potential causes for the high variance often found in group findings were also examined. The first empirical reports into psychobiological and psychiatric aspects from the early 1990s concluded that regular users demonstrated some selective psychobiological deficits, for instance worse declarative memory, or heightened depression. More recent research has covered a far wider range of psychobiological functions, and deficits have emerged in aspects of vision, higher cognitive skill, neurohormonal functioning, and foetal developmental outcomes. However, variance levels are often high, indicating that while some recreational users develop problems, others are less affected. Potential reasons for this high variance are debated. An explanatory model based on multi-factorial causation is then proposed. A number of theoretically driven research topics are suggested, in order to empirically investigate the potential causes for these diverse psychobiological deficits. Future neuroimaging studies should study the practical implications of any serotonergic and/or neurohormonal changes, using a wide range of functional measures.

Experimental and theoretical studies on tautomeric structures of a newly synthesized 2,2‧(hydrazine-1,2-diylidenebis(propan-1-yl-1-ylidene))diphenol

NASA Astrophysics Data System (ADS)

Karakurt, Tuncay; Cukurovali, Alaaddin; Subasi, Nuriye Tuna; Onaran, Abdurrahman; Ece, Abdulilah; Eker, Sıtkı; Kani, Ibrahim

2018-02-01

In the present study, a single crystal of a Schiff base, 2,2‧(hydrazine-1,2-diylidenebis(propan-1-yl-1-ylidene))diphenol, was synthesized. The structure of the synthesized crystal was confirmed by 1H and 13C NMR spectroscopic and X-ray diffraction analysis techniques. Experimental and theoretical studies were carried out on two tautomeric structures. It has been observed that the title compound studied can be in two different tautomeric forms, phenol-imine and keto-amine. Theoretical calculations have been performed to support experimental results. Accordingly, the geometric parameters of the compound were optimized by the density functional theory (DFT) method using the Gaussian 09 and Quantum Espresso (QE) packet program was used for periodic boundary conditions (PBC) studies. Furthermore, the compound was also tested for in vitro antifungal activity against Sclerotinia sclerotiorum, Alternaria solani, Fusarium oxysporum f. sp. lycopersici and Monilinia fructigena plant pathogens. Promising inhibition profiles were observed especially towards A. solani. Finally, molecular docking studies and post-docking procedure based on Molecular Mechanics-Generalized Born Surface Area (MM-GBSA) were also carried out to get insight into the compound's binding interactions with the potential. Although theoretical calculations showed that the phenol-imine form was more stable, keto-amine form was predicted to have better binding affinity which was concluded to result from loss of rotational entropy in phenol-imine upon binding. The results obtained here from both experimental and computational methods might serve as a potential lead in the development of novel anti-fungal agents.

Theoretical investigation of structural, electronic and optical properties of MgxBa1-xS, MgxBa1-xSe and MgxBa1-xTe ternary alloys using DFT based FP-LAPW approach

NASA Astrophysics Data System (ADS)

Bhattacharjee, Rahul; Chattopadhyaya, Surya

2017-11-01

Density functional theory (DFT) based full-potential linearized augmented plane wave (FP-LAPW) methodology has been employed to investigate theoretically the structural, electronic and optical properties of MgxBa1-xS, MgxBa1-xSe and MgxBa1-xTe ternary alloys for 0 ≤ x ≤ 1 in their rock-salt (B1) crystallographic phase. The exchange-correlation potentials for the structural properties have been computed using the Wu-Cohen generalized-gradient approximation (WC-GGA) scheme, while those for the electronic and optical properties have been computed using both the WC-GGA and the recently developed Tran-Blaha modified Becke-Johnson (TB-mBJ) schemes. The thermodynamic stability of all the ternary alloys have been investigated by calculating their respective enthalpy of formation. The atomic and orbital origin of different electronic states in the band structure of the compounds have been identified from the respective density of states (DOS). Using the approach of Zunger and co-workers, the microscopic origin of band gap bowing has been discussed in term of volume deformation, charge exchange and structural relaxation. Bonding characteristics among the constituent atoms of each of the specimens have been discussed from their charge density contour plots. Optical properties of the binary compounds and ternary alloys have been investigated theoretically in terms of their respective dielectric function, refractive index, normal incidence reflectivity and optical conductivity. Several calculated results have been compared with available experimental and other theoretical data.

Metallofullerenes as fuel cell electrocatalysts: a theoretical investigation of adsorbates on C59Pt.

PubMed

Gabriel, Margaret A; Genovese, Luigi; Krosnicki, Guillaume; Lemaire, Olivier; Deutsch, Thierry; Franco, Alejandro A

2010-08-28

Nano-structured electrode degradation in state-of-the-art polymer electrolyte membrane fuel cells (PEMFCs) is one of the main shortcomings that limit the large-scale development and commercialization of this technology. During normal operating conditions of the fuel cell, the PEMFC lifetime tends to be limited by coarsening of the cathode's Pt-based catalyst and by corrosion of the cathode's carbon black support. Because of their chemical properties, metallofullerenes such as C(59)Pt may be more electrochemically stable than the Pt/C mixture. In this paper we investigate, by theoretical methods, the stability of oxygen reduction reaction (ORR) adsorbates on the metallofullerene C(59)Pt and evaluate its potential as a PEMFC fuel cell catalyst.

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

Baalrud, S. D.; Lafleur, T.; Boswell, R. W.

Current-free double layers of the type reported in plasmas in the presence of an expanding magnetic field [C. Charles and R. W. Boswell, Appl. Phys. Lett. 82, 1356 (2003)] are modeled theoretically and with particle-in-cell/Monte Carlo simulations. Emphasis is placed on determining what mechanisms affect the electron velocity distribution function (EVDF) and how the EVDF influences the double layer. A theoretical model is developed based on depletion of electrons in certain velocity intervals due to wall losses and repletion of these intervals due to ionization and elastic electron scattering. This model is used to predict the range of neutral pressuresmore » over which a double layer can form and the electrostatic potential drop of the double layer. These predictions are shown to compare well with simulation results.« less

Broken flow symmetry explains the dynamics of small particles in deterministic lateral displacement arrays.

PubMed

Kim, Sung-Cheol; Wunsch, Benjamin H; Hu, Huan; Smith, Joshua T; Austin, Robert H; Stolovitzky, Gustavo

2017-06-27

Deterministic lateral displacement (DLD) is a technique for size fractionation of particles in continuous flow that has shown great potential for biological applications. Several theoretical models have been proposed, but experimental evidence has demonstrated that a rich class of intermediate migration behavior exists, which is not predicted. We present a unified theoretical framework to infer the path of particles in the whole array on the basis of trajectories in a unit cell. This framework explains many of the unexpected particle trajectories reported and can be used to design arrays for even nanoscale particle fractionation. We performed experiments that verify these predictions and used our model to develop a condenser array that achieves full particle separation with a single fluidic input.

Inferring electric fields and currents from ground magnetometer data - A test with theoretically derived inputs

NASA Technical Reports Server (NTRS)

Wolf, R. A.; Kamide, Y.

1983-01-01

Advanced techniques considered by Kamide et al. (1981) seem to have the potential for providing observation-based high time resolution pictures of the global ionospheric current and electric field patterns for interesting events. However, a reliance on the proposed magnetogram-inversion schemes for the deduction of global ionospheric current and electric field patterns requires proof that reliable results are obtained. 'Theoretical' tests of the accuracy of the magnetogram inversion schemes have, therefore, been considered. The present investigation is concerned with a test, involving the developed KRM algorithm and the Rice Convection Model (RCM). The test was successful in the sense that there was overall agreement between electric fields and currents calculated by the RCM and KRM schemes.

Constant potential pulse polarography

USGS Publications Warehouse

Christie, J.H.; Jackson, L.L.; Osteryoung, R.A.

1976-01-01

The new technique of constant potential pulse polarography, In which all pulses are to be the same potential, is presented theoretically and evaluated experimentally. The response obtained is in the form of a faradaic current wave superimposed on a constant capacitative component. Results obtained with a computer-controlled system exhibit a capillary response current similar to that observed In normal pulse polarography. Calibration curves for Pb obtained using a modified commercial pulse polarographic instrument are in good accord with theoretical predictions.

Revisiting the 'disaster and development' debate - Toward a broader understanding of macroeconomic risk and resilience.

PubMed

Mochizuki, Junko; Mechler, Reinhard; Hochrainer-Stigler, Stefan; Keating, Adriana; Williges, Keith

2014-01-01

Debate regarding the relationship between socioeconomic development and natural disasters remains at the fore of global discussions, as the potential risk from climate extremes and uncertainty pose an increasing threat to developmental prospects. This study reviews statistical investigations of disaster and development linkages, across topics of macroeconomic growth, public governance and others to identify key challenges to the current approach to macro-level statistical investigation. Both theoretically and qualitatively, disaster is known to affect development through a number of channels: haphazard development, weak institutions, lack of social safety nets and short-termism of our decision-making practices are some of the factors that drive natural disaster risk. Developmental potentials, including the prospects for sustainable and equitable growth, are in turn threatened by such accumulation of disaster risks. However, quantitative evidence regarding these complex causality chains remains contested due to several reasons. A number of theoretical and methodological limitations have been identified, including the use of GDP as a proxy measurement of welfare, issues with natural disaster damage reporting and the adoption of ad hoc model specifications and variables, which render interpretation and cross-comparison of statistical analysis difficult. Additionally, while greater attention is paid to economic and institutional parameters such as GDP, remittance, corruption and public expenditure as opposed to hard-to-quantify yet critical factors such as environmental conditions and social vulnerabilities. These are gaps in our approach that hamper our comprehensive understanding of the disaster-development nexus. Important areas for further research are identified, including recognizing and addressing the data constraints, incorporating sustainability and equity concerns through alternatives to GDP, and finding novel approaches to examining the complex and dynamic relationships between risk, vulnerability, resilience, adaptive capacity and development.

Determination of shift in energy of band edges and band gap of ZnSe spherical quantum dot

NASA Astrophysics Data System (ADS)

Siboh, Dutem; Kalita, Pradip Kumar; Sarma, Jayanta Kumar; Nath, Nayan Mani

2018-04-01

We have determined the quantum confinement induced shifts in energy of band edges and band gap with respect to size of ZnSe spherical quantum dot employing an effective confinement potential model developed in our earlier communication "arXiv:1705.10343". We have also performed phenomenological analysis of our theoretical results in comparison with available experimental data and observe a very good agreement in this regard. Phenomenological success achieved in this regard confirms validity of the confining potential model as well as signifies the capability and applicability of the ansatz for the effective confining potential to have reasonable information in the study of real nano-structured spherical systems.

Early Child Development and Nutrition: A Review of the Benefits and Challenges of Implementing Integrated Interventions.

PubMed

Hurley, Kristen M; Yousafzai, Aisha K; Lopez-Boo, Florencia

2016-03-01

Poor nutrition (substandard diet quantity and/or quality resulting in under- or overnutrition) and the lack of early learning opportunities contribute to the loss of developmental potential and life-long health and economic disparities among millions of children aged <5 y. Single-sector interventions representing either early child development (ECD) or nutrition have been linked to positive child development and/or nutritional status, and recommendations currently advocate for the development and testing of integrated interventions. We reviewed the theoretical and practical benefits and challenges of implementing integrated nutrition and ECD interventions along with the evidence for best practice and benefit-cost and concluded that the strong theoretical rationale for integration is more nuanced than the questions that the published empirical evidence have addressed. For example, further research is needed to 1) answer questions related to how integrated messaging influences caregiver characteristics such as well-being, knowledge, and behavior and how these influence early child nutrition and development outcomes; 2) understand population and nutritional contexts in which integrated interventions are beneficial; and 3) explore how varying implementation processes influence the efficacy, uptake, and cost-benefit of integrated nutrition and ECD interventions. © 2016 American Society for Nutrition.

Early Child Development and Nutrition: A Review of the Benefits and Challenges of Implementing Integrated Interventions1234

PubMed Central

Hurley, Kristen M; Yousafzai, Aisha K; Lopez-Boo, Florencia

2016-01-01

Poor nutrition (substandard diet quantity and/or quality resulting in under- or overnutrition) and the lack of early learning opportunities contribute to the loss of developmental potential and life-long health and economic disparities among millions of children aged <5 y. Single-sector interventions representing either early child development (ECD) or nutrition have been linked to positive child development and/or nutritional status, and recommendations currently advocate for the development and testing of integrated interventions. We reviewed the theoretical and practical benefits and challenges of implementing integrated nutrition and ECD interventions along with the evidence for best practice and benefit-cost and concluded that the strong theoretical rationale for integration is more nuanced than the questions that the published empirical evidence have addressed. For example, further research is needed to 1) answer questions related to how integrated messaging influences caregiver characteristics such as well-being, knowledge, and behavior and how these influence early child nutrition and development outcomes; 2) understand population and nutritional contexts in which integrated interventions are beneficial; and 3) explore how varying implementation processes influence the efficacy, uptake, and cost-benefit of integrated nutrition and ECD interventions. PMID:26980819

Game Theoretic Resolution of Water Conflicts

NASA Astrophysics Data System (ADS)

Tyagi, H.; Gosain, A. K.; Khosa, R.

2017-12-01

Water disputes are of multi-disciplinary nature and involve an array of natural, hydrological,social, political and economic issues. Operations Research based decision making methodshave been found to facilitate mathematical analysis of such multifaceted problems thatconsist of multiple stakeholders and their conflicting objectives. Game Theoretic techniqueslike Metagame and Hypergame Analysis can provide a framework for conceptualizing waterconflicts and envisaging their potential solutions. In the present research, firstly a Metagamemodel has been developed to identify range of plausible equilibrium outcomes for resolvingconflicts pertaining to water apportionments in a transboundary watercourse. Further, it hasbeen observed that the contenders often hide their strategies from other players to getfavorable water allocations. Consequently, there are widespread misinterpretations about thetactics of the competitors and contenders have to formulate their strategies entirely based ontheir perception about others. Accordingly, a Hypergame study has also been conducted tomodel the probable misperceptions that may exist amongst the river riparians. Thus, thecurrent study assesses the efficacy of Game Theoretic techniques as possible redressalmechanism for water conflicts.

Effective Drug Delivery in Diffuse Intrinsic Pontine Glioma: A Theoretical Model to Identify Potential Candidates

PubMed Central

El-Khouly, Fatma E.; van Vuurden, Dannis G.; Stroink, Thom; Hulleman, Esther; Kaspers, Gertjan J. L.; Hendrikse, N. Harry; Veldhuijzen van Zanten, Sophie E. M.

2017-01-01

Despite decades of clinical trials for diffuse intrinsic pontine glioma (DIPG), patient survival does not exceed 10% at two years post-diagnosis. Lack of benefit from systemic chemotherapy may be attributed to an intact bloodbrain barrier (BBB). We aim to develop a theoretical model including relevant physicochemical properties in order to review whether applied chemotherapeutics are suitable for passive diffusion through an intact BBB or whether local administration via convection-enhanced delivery (CED) may increase their therapeutic potential. Physicochemical properties (lipophilicity, molecular weight, and charge in physiological environment) of anticancer drugs historically and currently administered to DIPG patients, that affect passive diffusion over the BBB, were included in the model. Subsequently, the likelihood of BBB passage of these drugs was ascertained, as well as their potential for intratumoral administration via CED. As only non-molecularly charged, lipophilic, and relatively small sized drugs are likely to passively diffuse through the BBB, out of 51 drugs modeled, only 8 (15%)—carmustine, lomustine, erlotinib, vismodegib, lenalomide, thalidomide, vorinostat, and mebendazole—are theoretically qualified for systemic administration in DIPG. Local administration via CED might create more therapeutic options, excluding only positively charged drugs and drugs that are either prodrugs and/or only available as oral formulation. A wide variety of drugs have been administered systemically to DIPG patients. Our model shows that only few are likely to penetrate the BBB via passive diffusion, which may partly explain the lack of efficacy. Drug distribution via CED is less dependent on physicochemical properties and may increase the therapeutic options for DIPG. PMID:29164054

Improving Behavioral Support for Smoking Cessation in Pregnancy: What Are the Barriers to Stopping and Which Behavior Change Techniques Can Influence Them? Application of Theoretical Domains Framework

PubMed Central

Coleman-Haynes, Tom; Lorencatto, Fabiana; Ussher, Michael; Dyas, Jane; Coleman, Tim

2018-01-01

Behavioral support interventions are used to help pregnant smokers stop; however, of those tested, few are proven effective. Systematic research developing effective pregnancy-specific behavior change techniques (BCTs) is ongoing. This paper reports contributory work identifying potentially-effective BCTs relative to known important barriers and facilitators (B&Fs) to smoking cessation in pregnancy; to detect priority areas for BCTs development. A Nominal Group Technique with cessation experts (n = 12) elicited an expert consensus on B&Fs most influencing women’s smoking cessation and those most modifiable through behavioral support. Effective cessation interventions in randomized trials from a recent Cochrane review were coded into component BCTs using existing taxonomies. B&Fs were categorized using Theoretical Domains Framework (TDF) domains. Matrices, mapping BCT taxonomies against TDF domains, were consulted to investigate the extent to which BCTs in existing interventions target key B&Fs. Experts ranked ‘smoking a social norm’ and ‘quitting not a priority’ as most important barriers and ‘desire to protect baby’ an important facilitator to quitting. From 14 trials, 23 potentially-effective BCTs were identified (e.g., ‘information about consequences). Most B&Fs fell into ‘Social Influences’, ‘Knowledge’, ‘Emotions’ and ‘Intentions’ TDF domains; few potentially-effective BCTs mapped onto every TDF domain. B&Fs identified by experts as important to cessation, are not sufficiently targeted by BCT’s currently within interventions for smoking cessation in pregnancy. PMID:29462994

Improving Behavioral Support for Smoking Cessation in Pregnancy: What Are the Barriers to Stopping and Which Behavior Change Techniques Can Influence These? Application of Theoretical Domains Framework.

PubMed

Campbell, Katarzyna A; Fergie, Libby; Coleman-Haynes, Tom; Cooper, Sue; Lorencatto, Fabiana; Ussher, Michael; Dyas, Jane; Coleman, Tim

2018-02-17

Behavioral support interventions are used to help pregnant smokers stop; however, of those tested, few are proven effective. Systematic research developing effective pregnancy-specific behavior change techniques (BCTs) is ongoing. This paper reports contributory work identifying potentially-effective BCTs relative to known important barriers and facilitators (B&Fs) to smoking cessation in pregnancy; to detect priority areas for BCTs development. A Nominal Group Technique with cessation experts ( n = 12) elicited an expert consensus on B&Fs most influencing women's smoking cessation and those most modifiable through behavioral support. Effective cessation interventions in randomized trials from a recent Cochrane review were coded into component BCTs using existing taxonomies. B&Fs were categorized using Theoretical Domains Framework (TDF) domains. Matrices, mapping BCT taxonomies against TDF domains, were consulted to investigate the extent to which BCTs in existing interventions target key B&Fs. Experts ranked "smoking a social norm" and "quitting not a priority" as most important barriers and "desire to protect baby" an important facilitator to quitting. From 14 trials, 23 potentially-effective BCTs were identified (e.g., information about consequences). Most B&Fs fell into "Social Influences", "Knowledge", "Emotions" and "Intentions" TDF domains; few potentially-effective BCTs mapped onto every TDF domain. B&Fs identified by experts as important to cessation, are not sufficiently targeted by BCT's currently within interventions for smoking cessation in pregnancy.

Can we prevent OA? Epidemiology and public health insights and implications.

PubMed

Runhaar, Jos; Zhang, Yuqing

2018-05-01

This narrative review discusses the potential of prevention of OA in different stages of the disease. The theoretical background for primary prevention (i.e. prevention of occurrence of definite structural or clinical OA in subjects free of the disease) and secondary prevention (i.e. prevention of progression of the disease in subjects with pre-clinical pathological changes to the joint) is provided and evidence for effective strategies is discussed. Since direct evidence for the prevention of OA development and progression is scarce, indirect evidence enhancing our current knowledge on the potential of OA prevention is additionally discussed. Also, implications of preventive strategies for study design and public health are considered. Prevention of OA has great potential, but as deliberated in the current review, there are still large gaps in our current knowledge and the implications of preventive strategies for the development and progression of OA require consideration.

Flow through a very porous obstacle in a shallow channel.

PubMed

Creed, M J; Draper, S; Nishino, T; Borthwick, A G L

2017-04-01

A theoretical model, informed by numerical simulations based on the shallow water equations, is developed to predict the flow passing through and around a uniform porous obstacle in a shallow channel, where background friction is important. This problem is relevant to a number of practical situations, including flow through aquatic vegetation, the performance of arrays of turbines in tidal channels and hydrodynamic forces on offshore structures. To demonstrate this relevance, the theoretical model is used to (i) reinterpret core flow velocities in existing laboratory-based data for an array of emergent cylinders in shallow water emulating aquatic vegetation and (ii) reassess the optimum arrangement of tidal turbines to generate power in a tidal channel. Comparison with laboratory-based data indicates a maximum obstacle resistance (or minimum porosity) for which the present theoretical model is valid. When the obstacle resistance is above this threshold the shallow water equations do not provide an adequate representation of the flow, and the theoretical model over-predicts the core flow passing through the obstacle. The second application of the model confirms that natural bed resistance increases the power extraction potential for a partial tidal fence in a shallow channel and alters the optimum arrangement of turbines within the fence.

Theoretical kinetics study of the F((2)P) + NH3 hydrogen abstraction reaction.

PubMed

Espinosa-Garcia, J; Fernandez-Ramos, A; Suleimanov, Y V; Corchado, J C

2014-01-23

The hydrogen abstraction reaction of fluorine with ammonia represents a true chemical challenge because it is very fast, is followed by secondary abstraction reactions, which are also extremely fast, and presents an experimental/theoretical controversy about rate coefficients. Using a previously developed full-dimensional analytical potential energy surface, we found that the F + NH3 → HF + NH2 system is a barrierless reaction with intermediate complexes in the entry and exit channels. In order to understand the reactivity of the title reaction, thermal rate coefficidents were calculated using two approaches: ring polymer molecular dynamics and quasi-classical trajectory calculations, and these were compared with available experimental data for the common temperature range 276-327 K. The theoretical results obtained show behavior practically independent of temperature, reproducing Walther-Wagner's experiment, but in contrast with Persky's more recent experiment. However, quantitatively, our results are 1 order of magnitude larger than those of Walther-Wagner and reasonably agree with the Persky at the lowest temperature, questioning so Walther-Wagner's older data. At present, the reason for this discrepancy is not clear, although we point out some possible reasons in the light of current theoretical calculations.

Models and theories of prescribing decisions: A review and suggested a new model

PubMed Central

Mohaidin, Zurina

2017-01-01

To date, research on the prescribing decisions of physician lacks sound theoretical foundations. In fact, drug prescribing by doctors is a complex phenomenon influenced by various factors. Most of the existing studies in the area of drug prescription explain the process of decision-making by physicians via the exploratory approach rather than theoretical. Therefore, this review is an attempt to suggest a value conceptual model that explains the theoretical linkages existing between marketing efforts, patient and pharmacist and physician decision to prescribe the drugs. The paper follows an inclusive review approach and applies the previous theoretical models of prescribing behaviour to identify the relational factors. More specifically, the report identifies and uses several valuable perspectives such as the ‘persuasion theory - elaboration likelihood model’, the stimuli–response marketing model’, the ‘agency theory’, the theory of planned behaviour,’ and ‘social power theory,’ in developing an innovative conceptual paradigm. Based on the combination of existing methods and previous models, this paper suggests a new conceptual model of the physician decision-making process. This unique model has the potential for use in further research. PMID:28690701

Spectroscopic and density functional theory studies of 5,7,3',5'-tetrahydroxyflavanone from the leaves of Olea ferruginea.

PubMed

Hashmi, Muhammad Ali; Khan, Afsar; Ayub, Khurshid; Farooq, Umar

2014-07-15

5,7,3',5'-Tetrahydroxyflavanone (1) was isolated from the leaves of Olea ferruginea and a theoretical model was developed for obtaining the electronic and spectroscopic properties of 1. The geometric and electronic properties were calculated at B3LYP/6-311 G (d, p) level of Density Functional Theory (DFT). The theoretical data was in good agreement with the experimental one. The optimized geometric parameters of compound 1 were calculated for the first time. The theoretical vibrational frequencies of 1 were found to correlate with the experimental IR spectrum after a scaling factor of 0.9811. The UV and NMR spectral data computed theoretically were in good agreement with the experimental data. Electronic properties of the compound i.e., ionization potential (IP), electron affinity (EA), coefficients of HOMO and LUMO were estimated computationally for the first time which can be used to explain its antioxidant as well as other related activities and more active sites on it. The intermolecular interactions and their effects on IR frequencies, electronic and geometric parameters were simulated using water molecule as a model for hydrogen bonding with flavonoid hydroxyl groups. Copyright © 2014 Elsevier B.V. All rights reserved.

Spectroscopic and density functional theory studies of 5,7,3‧,5‧-tetrahydroxyflavanone from the leaves of Olea ferruginea

NASA Astrophysics Data System (ADS)

Hashmi, Muhammad Ali; Khan, Afsar; Ayub, Khurshid; Farooq, Umar

2014-07-01

5,7,3‧,5‧-Tetrahydroxyflavanone (1) was isolated from the leaves of Olea ferruginea and a theoretical model was developed for obtaining the electronic and spectroscopic properties of 1. The geometric and electronic properties were calculated at B3LYP/6-311 G (d, p) level of Density Functional Theory (DFT). The theoretical data was in good agreement with the experimental one. The optimized geometric parameters of compound 1 were calculated for the first time. The theoretical vibrational frequencies of 1 were found to correlate with the experimental IR spectrum after a scaling factor of 0.9811. The UV and NMR spectral data computed theoretically were in good agreement with the experimental data. Electronic properties of the compound i.e., ionization potential (IP), electron affinity (EA), coefficients of HOMO and LUMO were estimated computationally for the first time which can be used to explain its antioxidant as well as other related activities and more active sites on it. The intermolecular interactions and their effects on IR frequencies, electronic and geometric parameters were simulated using water molecule as a model for hydrogen bonding with flavonoid hydroxyl groups.

Medicine as a Community of Practice: Implications for Medical Education.

PubMed

Cruess, Richard L; Cruess, Sylvia R; Steinert, Yvonne

2018-02-01

The presence of a variety of independent learning theories makes it difficult for medical educators to construct a comprehensive theoretical framework for medical education, resulting in numerous and often unrelated curricular, instructional, and assessment practices. Linked with an understanding of identity formation, the concept of communities of practice could provide such a framework, emphasizing the social nature of learning. Individuals wish to join the community, moving from legitimate peripheral to full participation, acquiring the identity of community members and accepting the community's norms.Having communities of practice as the theoretical basis of medical education does not diminish the value of other learning theories. Communities of practice can serve as the foundational theory, and other theories can provide a theoretical basis for the multiple educational activities that take place within the community, thus helping create an integrated theoretical approach.Communities of practice can guide the development of interventions to make medical education more effective and can help both learners and educators better cope with medical education's complexity. An initial step is to acknowledge the potential of communities of practice as the foundational theory. Educational initiatives that could result from this approach include adding communities of practice to the cognitive base; actively engaging students in joining the community; creating a welcoming community; expanding the emphasis on explicitly addressing role modeling, mentoring, experiential learning, and reflection; providing faculty development to support the program; and recognizing the necessity to chart progress toward membership in the community.

A Diverse Community To Study Communities: Integration of Experiments and Mathematical Models To Study Microbial Consortia.

PubMed

Succurro, Antonella; Moejes, Fiona Wanjiku; Ebenhöh, Oliver

2017-08-01

The last few years have seen the advancement of high-throughput experimental techniques that have produced an extraordinary amount of data. Bioinformatics and statistical analyses have become instrumental to interpreting the information coming from, e.g., sequencing data and often motivate further targeted experiments. The broad discipline of "computational biology" extends far beyond the well-established field of bioinformatics, but it is our impression that more theoretical methods such as the use of mathematical models are not yet as well integrated into the research studying microbial interactions. The empirical complexity of microbial communities presents challenges that are difficult to address with in vivo / in vitro approaches alone, and with microbiology developing from a qualitative to a quantitative science, we see stronger opportunities arising for interdisciplinary projects integrating theoretical approaches with experiments. Indeed, the addition of in silico experiments, i.e., computational simulations, has a discovery potential that is, unfortunately, still largely underutilized and unrecognized by the scientific community. This minireview provides an overview of mathematical models of natural ecosystems and emphasizes that one critical point in the development of a theoretical description of a microbial community is the choice of problem scale. Since this choice is mostly dictated by the biological question to be addressed, in order to employ theoretical models fully and successfully it is vital to implement an interdisciplinary view at the conceptual stages of the experimental design. Copyright © 2017 Succurro et al.

Assessing implementation difficulties in tobacco use prevention and cessation counselling among dental providers

PubMed Central

2011-01-01

Background Tobacco use adversely affects oral health. Clinical guidelines recommend that dental providers promote tobacco abstinence and provide patients who use tobacco with brief tobacco use cessation counselling. Research shows that these guidelines are seldom implemented, however. To improve guideline adherence and to develop effective interventions, it is essential to understand provider behaviour and challenges to implementation. This study aimed to develop a theoretically informed measure for assessing among dental providers implementation difficulties related to tobacco use prevention and cessation (TUPAC) counselling guidelines, to evaluate those difficulties among a sample of dental providers, and to investigate a possible underlying structure of applied theoretical domains. Methods A 35-item questionnaire was developed based on key theoretical domains relevant to the implementation behaviours of healthcare providers. Specific items were drawn mostly from the literature on TUPAC counselling studies of healthcare providers. The data were collected from dentists (n = 73) and dental hygienists (n = 22) in 36 dental clinics in Finland using a web-based survey. Of 95 providers, 73 participated (76.8%). We used Cronbach's alpha to ascertain the internal consistency of the questionnaire. Mean domain scores were calculated to assess different aspects of implementation difficulties and exploratory factor analysis to assess the theoretical domain structure. The authors agreed on the labels assigned to the factors on the basis of their component domains and the broader behavioural and theoretical literature. Results Internal consistency values for theoretical domains varied from 0.50 ('emotion') to 0.71 ('environmental context and resources'). The domain environmental context and resources had the lowest mean score (21.3%; 95% confidence interval [CI], 17.2 to 25.4) and was identified as a potential implementation difficulty. The domain emotion provided the highest mean score (60%; 95% CI, 55.0 to 65.0). Three factors were extracted that explain 70.8% of the variance: motivation (47.6% of variance, α = 0.86), capability (13.3% of variance, α = 0.83), and opportunity (10.0% of variance, α = 0.71). Conclusions This study demonstrated a theoretically informed approach to identifying possible implementation difficulties in TUPAC counselling among dental providers. This approach provides a method for moving from diagnosing implementation difficulties to designing and evaluating interventions. PMID:21615948

Including diverging electrostatic potential in 3D-RISM theory: The charged wall case.

PubMed

Vyalov, Ivan; Rocchia, Walter

2018-03-21

Although three-dimensional site-site molecular integral equations of liquids are a powerful tool of the modern theoretical chemistry, their applications to the problem of characterizing the electrical double layer originating at the solid-liquid interface with a macroscopic substrate are severely limited by the fact that an infinitely extended charged plane generates a divergent electrostatic potential. Such potentials cannot be treated within the standard 3D-Reference Interaction Site Model equation solution framework since it leads to functions that are not Fourier transformable. In this paper, we apply a renormalization procedure to overcome this obstacle. We then check the validity and numerical accuracy of the proposed computational scheme on the prototypical gold (111) surface in contact with water/alkali chloride solution. We observe that despite the proposed method requires, to achieve converged charge densities, a higher spatial resolution than that suited to the estimation of biomolecular solvation with either 3D-RISM or continuum electrostatics approaches, it still is computationally efficient. Introducing the electrostatic potential of an infinite wall, which is periodic in 2 dimensions, we avoid edge effects, permit a robust integration of Poisson's equation, and obtain the 3D electrostatic potential profile for the first time in such calculations. We show that the potential within the electrical double layer presents oscillations which are not grasped by the Debye-Hückel and Gouy-Chapman theories. This electrostatic potential deviates from its average of up to 1-2 V at small distances from the substrate along the lateral directions. Applications of this theoretical development are relevant, for example, for liquid scanning tunneling microscopy imaging.

Including diverging electrostatic potential in 3D-RISM theory: The charged wall case

NASA Astrophysics Data System (ADS)

Vyalov, Ivan; Rocchia, Walter

2018-03-01

Although three-dimensional site-site molecular integral equations of liquids are a powerful tool of the modern theoretical chemistry, their applications to the problem of characterizing the electrical double layer originating at the solid-liquid interface with a macroscopic substrate are severely limited by the fact that an infinitely extended charged plane generates a divergent electrostatic potential. Such potentials cannot be treated within the standard 3D-Reference Interaction Site Model equation solution framework since it leads to functions that are not Fourier transformable. In this paper, we apply a renormalization procedure to overcome this obstacle. We then check the validity and numerical accuracy of the proposed computational scheme on the prototypical gold (111) surface in contact with water/alkali chloride solution. We observe that despite the proposed method requires, to achieve converged charge densities, a higher spatial resolution than that suited to the estimation of biomolecular solvation with either 3D-RISM or continuum electrostatics approaches, it still is computationally efficient. Introducing the electrostatic potential of an infinite wall, which is periodic in 2 dimensions, we avoid edge effects, permit a robust integration of Poisson's equation, and obtain the 3D electrostatic potential profile for the first time in such calculations. We show that the potential within the electrical double layer presents oscillations which are not grasped by the Debye-Hückel and Gouy-Chapman theories. This electrostatic potential deviates from its average of up to 1-2 V at small distances from the substrate along the lateral directions. Applications of this theoretical development are relevant, for example, for liquid scanning tunneling microscopy imaging.

Calculation of photoionization cross section near auto-ionizing lines and magnesium photoionization cross section near threshold

NASA Technical Reports Server (NTRS)

Moore, E. N.; Altick, P. L.

1972-01-01

The research performed is briefly reviewed. A simple method was developed for the calculation of continuum states of atoms when autoionization is present. The method was employed to give the first theoretical cross section for beryllium and magnesium; the results indicate that the values used previously at threshold were sometimes seriously in error. These threshold values have potential applications in astrophysical abundance estimates.

Optimizing Biorefinery Design and Operations via Linear Programming Models

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

Talmadge, Michael; Batan, Liaw; Lamers, Patrick

The ability to assess and optimize economics of biomass resource utilization for the production of fuels, chemicals and power is essential for the ultimate success of a bioenergy industry. The team of authors, consisting of members from the National Renewable Energy Laboratory (NREL) and the Idaho National Laboratory (INL), has developed simple biorefinery linear programming (LP) models to enable the optimization of theoretical or existing biorefineries. The goal of this analysis is to demonstrate how such models can benefit the developing biorefining industry. It focuses on a theoretical multi-pathway, thermochemical biorefinery configuration and demonstrates how the biorefinery can use LPmore » models for operations planning and optimization in comparable ways to the petroleum refining industry. Using LP modeling tools developed under U.S. Department of Energy's Bioenergy Technologies Office (DOE-BETO) funded efforts, the authors investigate optimization challenges for the theoretical biorefineries such as (1) optimal feedstock slate based on available biomass and prices, (2) breakeven price analysis for available feedstocks, (3) impact analysis for changes in feedstock costs and product prices, (4) optimal biorefinery operations during unit shutdowns / turnarounds, and (5) incentives for increased processing capacity. These biorefinery examples are comparable to crude oil purchasing and operational optimization studies that petroleum refiners perform routinely using LPs and other optimization models. It is important to note that the analyses presented in this article are strictly theoretical and they are not based on current energy market prices. The pricing structure assigned for this demonstrative analysis is consistent with $4 per gallon gasoline, which clearly assumes an economic environment that would favor the construction and operation of biorefineries. The analysis approach and examples provide valuable insights into the usefulness of analysis tools for maximizing the potential benefits of biomass utilization for production of fuels, chemicals and power.« less

Viscous/potential flow about multi-element two-dimensional and infinite-span swept wings: Theory and experiment

NASA Technical Reports Server (NTRS)

Olson, L. E.; Dvorak, F. A.

1975-01-01

The viscous subsonic flow past two-dimensional and infinite-span swept multi-component airfoils is studied theoretically and experimentally. The computerized analysis is based on iteratively coupled boundary layer and potential flow analysis. The method, which is restricted to flows with only slight separation, gives surface pressure distribution, chordwise and spanwise boundary layer characteristics, lift, drag, and pitching moment for airfoil configurations with up to four elements. Merging confluent boundary layers are treated. Theoretical predictions are compared with an exact theoretical potential flow solution and with experimental measures made in the Ames 40- by 80-Foot Wind Tunnel for both two-dimensional and infinite-span swept wing configurations. Section lift characteristics are accurately predicted for zero and moderate sweep angles where flow separation effects are negligible.

Assessing Repetitive Negative Thinking Using Categorical and Transdiagnostic Approaches: A Comparison and Validation of Three Polish Language Adaptations of Self-Report Questionnaires.

PubMed

Kornacka, Monika; Buczny, Jacek; Layton, Rebekah L

2016-01-01

Repetitive negative thinking (RNT) is a transdiagnostic process involved in the risk, maintenance, and relapse of serious conditions including mood disorders, anxiety, eating disorders, and addictions. Processing mode theory provides a theoretical model to assess, research, and treat RNT using a transdiagnostic approach. Clinical researchers also often employ categorical approaches to RNT, including a focus on depressive rumination or worry, for similar purposes. Three widely used self-report questionnaires have been developed to assess these related constructs: the Ruminative Response Scale (RRS), the Perseverative Thinking Questionnaire (PTQ), and the Mini-Cambridge Exeter Repetitive Thought Scale (Mini-CERTS). Yet these scales have not previously been used in conjunction, despite useful theoretical distinctions only available in Mini-CERTS. The present validation of the methods in a Polish speaking population provides psychometric parameters estimates that contribute to current efforts to increase reliable replication of theoretical outcomes. Moreover, the following study aims to present particular characteristics and a comparison of the three methods. Although there has been some exploration of a categorical approach, the comparison of transdiagnostic methods is still lacking. These methods are particularly relevant for developing and evaluating theoretically based interventions like concreteness training, an emerging field of increasing interest, which can be used to address the maladaptive processing mode in RNT that can lead to depression and other disorders. Furthermore, the translation of these measures enables the examination of possible cross-cultural structural differences that may lead to important theoretical progress in the measurement and classification of RNT. The results support the theoretical hypothesis. As expected, the dimensions of brooding, general repetitive negative thinking, as well as abstract analytical thinking, can all be classified as unconstructive repetitive thinking. The particular characteristics of each scale and potential practical applications in clinical and research are discussed.

Application of theory to enhance audit and feedback interventions to increase the uptake of evidence-based transfusion practice: an intervention development protocol.

PubMed

Gould, Natalie J; Lorencatto, Fabiana; Stanworth, Simon J; Michie, Susan; Prior, Maria E; Glidewell, Liz; Grimshaw, Jeremy M; Francis, Jill J

2014-07-29

Audits of blood transfusion demonstrate around 20% transfusions are outside national recommendations and guidelines. Audit and feedback is a widely used quality improvement intervention but effects on clinical practice are variable, suggesting potential for enhancement. Behavioural theory, theoretical frameworks of behaviour change and behaviour change techniques provide systematic processes to enhance intervention. This study is part of a larger programme of work to promote the uptake of evidence-based transfusion practice. The objectives of this study are to design two theoretically enhanced audit and feedback interventions; one focused on content and one on delivery, and investigate the feasibility and acceptability. Study A (Content): A coding framework based on current evidence regarding audit and feedback, and behaviour change theory and frameworks will be developed and applied as part of a structured content analysis to specify the key components of existing feedback documents. Prototype feedback documents with enhanced content and also a protocol, describing principles for enhancing feedback content, will be developed. Study B (Delivery): Individual semi-structured interviews with healthcare professionals and observations of team meetings in four hospitals will be used to specify, and identify views about, current audit and feedback practice. Interviews will be based on a topic guide developed using the Theoretical Domains Framework and the Consolidated Framework for Implementation Research. Analysis of transcripts based on these frameworks will form the evidence base for developing a protocol describing an enhanced intervention that focuses on feedback delivery. Study C (Feasibility and Acceptability): Enhanced interventions will be piloted in four hospitals. Semi-structured interviews, questionnaires and observations will be used to assess feasibility and acceptability. This intervention development work reflects the UK Medical Research Council's guidance on development of complex interventions, which emphasises the importance of a robust theoretical basis for intervention design and recommends systematic assessment of feasibility and acceptability prior to taking interventions to evaluation in a full-scale randomised study. The work-up includes specification of current practice so that, in the trials to be conducted later in this programme, there will be a clear distinction between the control (usual practice) conditions and the interventions to be evaluated.

Molecular Dynamic Simulations of Interaction of an AFM Probe with the Surface of an SCN Sample

NASA Technical Reports Server (NTRS)

Bune, Adris; Kaukler, William; Rose, M. Franklin (Technical Monitor)

2001-01-01

Molecular dynamic (MD) simulations is conducted in order to estimate forces of probe-substrate interaction in the Atomic Force Microscope (AFM). First a review of available molecular dynamic techniques is given. Implementation of MD simulation is based on an object-oriented code developed at the University of Delft. Modeling of the sample material - succinonitrile (SCN) - is based on the Lennard-Jones potentials. For the polystyrene probe an atomic interaction potential is used. Due to object-oriented structure of the code modification of an atomic interaction potential is straight forward. Calculation of melting temperature is used for validation of the code and of the interaction potentials. Various fitting parameters of the probe-substrate interaction potentials are considered, as potentials fitted to certain properties and temperature ranges may not be reliable for the others. This research provides theoretical foundation for an interpretation of actual measurements of an interaction forces using AFM.

Stochastic modelling, Bayesian inference, and new in vivo measurements elucidate the debated mtDNA bottleneck mechanism

PubMed Central

Johnston, Iain G; Burgstaller, Joerg P; Havlicek, Vitezslav; Kolbe, Thomas; Rülicke, Thomas; Brem, Gottfried; Poulton, Jo; Jones, Nick S

2015-01-01

Dangerous damage to mitochondrial DNA (mtDNA) can be ameliorated during mammalian development through a highly debated mechanism called the mtDNA bottleneck. Uncertainty surrounding this process limits our ability to address inherited mtDNA diseases. We produce a new, physically motivated, generalisable theoretical model for mtDNA populations during development, allowing the first statistical comparison of proposed bottleneck mechanisms. Using approximate Bayesian computation and mouse data, we find most statistical support for a combination of binomial partitioning of mtDNAs at cell divisions and random mtDNA turnover, meaning that the debated exact magnitude of mtDNA copy number depletion is flexible. New experimental measurements from a wild-derived mtDNA pairing in mice confirm the theoretical predictions of this model. We analytically solve a mathematical description of this mechanism, computing probabilities of mtDNA disease onset, efficacy of clinical sampling strategies, and effects of potential dynamic interventions, thus developing a quantitative and experimentally-supported stochastic theory of the bottleneck. DOI: http://dx.doi.org/10.7554/eLife.07464.001 PMID:26035426

Theoretical Perspectives Guiding QOL Indicator Projects

ERIC Educational Resources Information Center

Sirgy, M. Joseph

2011-01-01

Most of the theoretically based QOL indicators projects can be classified in terms of six major theoretical concepts: (a) socio-economic development (b) personal utility, (c) just society, (d) human development, (e) sustainability, and (f) functioning. I explain the core aspects of these six theoretical paradigms and show how they help guide QOL…

Total deposition of ultrafine particles in the lungs of healthy men and women: experimental and theoretical results

PubMed Central

2016-01-01

Background Inhaled ultrafine particles (UFP) may induce greater adverse respiratory effects than larger particles occurring in the ambient atmosphere. Due to this potential of UFP to act as triggers for diverse lung injuries medical as well as physical research has been increasingly focused on the exact deposition behavior of the particles in lungs of various probands. Main purpose of the present study was the presentation of experimental and theoretical data of total, regional, and local UFP deposition in the lungs of men and women. Methods Both experiments and theoretical simulations were carried out by using particle sizes of 0.04, 0.06, 0.08, and 0.10 µm [number median diameters (NMD)]. Inhalation of UFP took place by application of predefined tidal volumes (500, 750, and 1,000 mL) and respiratory flow rates (150, 250, 375, and 500 mL·s−1). For male subjects a functional residual capacity (FRC) of 3,911±892 mL was measured, whereas female probands had a FRC of 3,314±547 mL. Theoretical predictions were based on (I) a stochastic model of the tracheobronchial tree; (II) particle transport computations according to a random walk algorithm; and (III) empirical formulae for the description of UFP deposition. Results Total deposition fractions (TDF) are marked by a continuous diminution with increasing particle size. Whilst particles measuring 0.04 µm in size deposit in the respiratory tract by 40–70%, particles with a size of 0.10 µm exhibit deposition values ranging from 20% to 45%. Except for the largest particles studied here TDF of female probands are higher than those obtained for male probands. Differences between experimental and theoretical results are most significant for 0.10 µm particles, but never exceed 20%. Predictions of regional (extrathoracic, tracheobronchial, alveolar) UFP deposition show clearly that females tend to develop higher tracheobronchial and alveolar deposition fractions than males. This discrepancy is also confirmed by airway generation-specific deposition, which is permanently higher in women than in men. Conclusions From the experimental data and modeling predictions it can be concluded that females bear a slightly higher potential to develop lung insufficiencies after exposure to UFP than males. Besides higher deposition fractions occurring in female subjects, also total lung deposition dose is noticeably enhanced. PMID:27429960

Total deposition of ultrafine particles in the lungs of healthy men and women: experimental and theoretical results.

PubMed

Sturm, Robert

2016-06-01

Inhaled ultrafine particles (UFP) may induce greater adverse respiratory effects than larger particles occurring in the ambient atmosphere. Due to this potential of UFP to act as triggers for diverse lung injuries medical as well as physical research has been increasingly focused on the exact deposition behavior of the particles in lungs of various probands. Main purpose of the present study was the presentation of experimental and theoretical data of total, regional, and local UFP deposition in the lungs of men and women. Both experiments and theoretical simulations were carried out by using particle sizes of 0.04, 0.06, 0.08, and 0.10 µm [number median diameters (NMD)]. Inhalation of UFP took place by application of predefined tidal volumes (500, 750, and 1,000 mL) and respiratory flow rates (150, 250, 375, and 500 mL·s(-1)). For male subjects a functional residual capacity (FRC) of 3,911±892 mL was measured, whereas female probands had a FRC of 3,314±547 mL. Theoretical predictions were based on (I) a stochastic model of the tracheobronchial tree; (II) particle transport computations according to a random walk algorithm; and (III) empirical formulae for the description of UFP deposition. Total deposition fractions (TDF) are marked by a continuous diminution with increasing particle size. Whilst particles measuring 0.04 µm in size deposit in the respiratory tract by 40-70%, particles with a size of 0.10 µm exhibit deposition values ranging from 20% to 45%. Except for the largest particles studied here TDF of female probands are higher than those obtained for male probands. Differences between experimental and theoretical results are most significant for 0.10 µm particles, but never exceed 20%. Predictions of regional (extrathoracic, tracheobronchial, alveolar) UFP deposition show clearly that females tend to develop higher tracheobronchial and alveolar deposition fractions than males. This discrepancy is also confirmed by airway generation-specific deposition, which is permanently higher in women than in men. From the experimental data and modeling predictions it can be concluded that females bear a slightly higher potential to develop lung insufficiencies after exposure to UFP than males. Besides higher deposition fractions occurring in female subjects, also total lung deposition dose is noticeably enhanced.

Incorporating immigrants: integrating theoretical frameworks of adaptation.

PubMed

Treas, Judith

2015-03-01

To encourage research on immigrants and aging by analyzing theoretical commonalities in the two fields and identifying potential contributions of aging theories, specifically to the understanding of neglected age differences in the pace of immigrant incorporation. Survey of the historical development of assimilation theory and its successors and systematic comparison of key concepts in aging and immigrant incorporation theories. Studies of immigrants, as well as of the life course, trace their origins to the Chicago School at the turn of the 20th century. Today, both theoretical perspectives emphasize adaptation as a time-dependent, multidimensional, nonlinear, and multidirectional process. Immigrant incorporation theories have not fully engaged with a key concern of aging theory-why there are age differences. Insights from cognitive aging and developmental biology, life-span developmental psychology, and age stratification and the life course suggest explanations for age differences in the speed of immigrant incorporation. Theories of adaptation to aging and theories of immigrant incorporation developed so independently that they neglected the subject they have in common, namely, older immigrants. Because they address similar conceptual problems and share key assumptions, a productive dialogue between two vibrant fields is long overdue. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Biological monitoring of 2,4,5-trichlorophenol (I): preparation of antibodies and development of an immunoassay using theoretical models.

PubMed

Nichkova, Mikaela; Galve, Roger; Marco, M-Pilar

2002-11-01

Antibodies against 2,4,5-trichlorophenol have been prepared after theoretical and molecular modeling chemical studies of three potential immunizing haptens with the aim to find out the one mimicking best the target analyte. Competitive direct and indirect ELISAs have been developed after screening a battery of haptenized enzyme tracers and coating antigens, respectively. The relation between the degree of heterology of the competitor and the resulting immunoassay detectability has been investigated according to the electronic similarities of the competitor haptens with the target analyte taking in consideration their pK(a) values. These studies have been performed using theoretical and molecular modeling tools to find out their electronic distribution at their minimum energetic levels. The results suggest that the competitors should have a high homology to produced assays with good detectability values. On the other hand detectability improves when lowering the hapten density of the competitors. An indirect competitive ELISA has been finally selected for further investigation. The immunoassay has an IC(50) value of 0.6 microg L(-)(1) and a limit of detection of 0.084 microg L(-)(1). The selectivity of the assay is high in relation to other chlorophenols frequently present in real samples. In contrast, the brominated analogues may also be recognized with this assay.

From psycho-social theory to sustainable classroom practice: developing a research-based teacher-delivered sex education programme.

PubMed

Wight, D; Abraham, C

2000-02-01

This paper describes the development of a theoretically based sex education programme currently undergoing a randomized controlled trial in the UK. It considers some of the practical difficulties involved in translating research-based conclusions into acceptable, replicable and potentially effective classroom lessons. The discussion acknowledges that the implications of social psychological research and the requirements of rigorous evaluation may conflict with accepted principles inherent in current sex education practice. It also emphasizes that theoretical ideas must be carefully embedded in lessons which are informed by an awareness of classroom culture, and the needs and skills of teachers. For example, the use of same-sex student groups to reflect on the gendered construction of sexuality may be problematic. Materials must be tailored to recipients' circumstances, which may require substituting for limited experience with the use of detailed scripts and scenarios. Furthermore, role-play techniques for sexual negotiation that work elsewhere may not be effective in the UK. The use of trigger video sessions and other techniques are recommended. Finally, the problems involved in promoting condom-related skills are discussed. The paper concludes that, if an intervention is to be sustainable beyond the research stage, it must be designed to overcome such problems while remaining theoretically informed.

The dynamics of adapting, unregulated populations and a modified fundamental theorem.

PubMed

O'Dwyer, James P

2013-01-06

A population in a novel environment will accumulate adaptive mutations over time, and the dynamics of this process depend on the underlying fitness landscape: the fitness of and mutational distance between possible genotypes in the population. Despite its fundamental importance for understanding the evolution of a population, inferring this landscape from empirical data has been problematic. We develop a theoretical framework to describe the adaptation of a stochastic, asexual, unregulated, polymorphic population undergoing beneficial, neutral and deleterious mutations on a correlated fitness landscape. We generate quantitative predictions for the change in the mean fitness and within-population variance in fitness over time, and find a simple, analytical relationship between the distribution of fitness effects arising from a single mutation, and the change in mean population fitness over time: a variant of Fisher's 'fundamental theorem' which explicitly depends on the form of the landscape. Our framework can therefore be thought of in three ways: (i) as a set of theoretical predictions for adaptation in an exponentially growing phase, with applications in pathogen populations, tumours or other unregulated populations; (ii) as an analytically tractable problem to potentially guide theoretical analysis of regulated populations; and (iii) as a basis for developing empirical methods to infer general features of a fitness landscape.

Interfacing theories of program with theories of evaluation for advancing evaluation practice: Reductionism, systems thinking, and pragmatic synthesis.

PubMed

Chen, Huey T

2016-12-01

Theories of program and theories of evaluation form the foundation of program evaluation theories. Theories of program reflect assumptions on how to conceptualize an intervention program for evaluation purposes, while theories of evaluation reflect assumptions on how to design useful evaluation. These two types of theories are related, but often discussed separately. This paper attempts to use three theoretical perspectives (reductionism, systems thinking, and pragmatic synthesis) to interface them and discuss the implications for evaluation practice. Reductionism proposes that an intervention program can be broken into crucial components for rigorous analyses; systems thinking view an intervention program as dynamic and complex, requiring a holistic examination. In spite of their contributions, reductionism and systems thinking represent the extreme ends of a theoretical spectrum; many real-world programs, however, may fall in the middle. Pragmatic synthesis is being developed to serve these moderate- complexity programs. These three theoretical perspectives have their own strengths and challenges. Knowledge on these three perspectives and their evaluation implications can provide a better guide for designing fruitful evaluations, improving the quality of evaluation practice, informing potential areas for developing cutting-edge evaluation approaches, and contributing to advancing program evaluation toward a mature applied science. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of Food Waste Prevention and Recycling Strategies Using a Multilayer Systems Approach.

PubMed

Hamilton, Helen A; Peverill, M Samantha; Müller, Daniel B; Brattebø, Helge

2015-12-15

Food waste (FW) generates large upstream and downstream emissions to the environment and unnecessarily consumes natural resources, potentially affecting future food security. The ecological impacts of FW can be addressed by the upstream strategies of FW prevention or by downstream strategies of FW recycling, including energy and nutrient recovery. While FW recycling is often prioritized in practice, the ecological implications of the two strategies remain poorly understood from a quantitative systems perspective. Here, we develop a multilayer systems framework and scenarios to quantify the implications of food waste strategies on national biomass, energy, and phosphorus (P) cycles, using Norway as a case study. We found that (i) avoidable food waste in Norway accounts for 17% of sold food; (ii) 10% of the avoidable food waste occurs at the consumption stage, while industry and retailers account for only 7%; (iii) the theoretical potential for systems-wide net process energy savings is 16% for FW prevention and 8% for FW recycling; (iv) the theoretical potential for systems-wide P savings is 21% for FW prevention and 9% for FW recycling; (v) while FW recycling results in exclusively domestic nutrient and energy savings, FW prevention leads to domestic and international savings due to large food imports; (vi) most effective is a combination of prevention and recycling, however, FW prevention reduces the potential for FW recycling and therefore needs to be prioritized to avoid potential overcapacities for FW recycling.

Fluid-structure finite-element vibrational analysis

NASA Technical Reports Server (NTRS)

Feng, G. C.; Kiefling, L.

1974-01-01

A fluid finite element has been developed for a quasi-compressible fluid. Both kinetic and potential energy are expressed as functions of nodal displacements. Thus, the formulation is similar to that used for structural elements, with the only differences being that the fluid can possess gravitational potential, and the constitutive equations for fluid contain no shear coefficients. Using this approach, structural and fluid elements can be used interchangeably in existing efficient sparse-matrix structural computer programs such as SPAR. The theoretical development of the element formulations and the relationships of the local and global coordinates are shown. Solutions of fluid slosh, liquid compressibility, and coupled fluid-shell oscillation problems which were completed using a temporary digital computer program are shown. The frequency correlation of the solutions with classical theory is excellent.

Inverse problems in quantum chemistry

NASA Astrophysics Data System (ADS)

Karwowski, Jacek

Inverse problems constitute a branch of applied mathematics with well-developed methodology and formalism. A broad family of tasks met in theoretical physics, in civil and mechanical engineering, as well as in various branches of medical and biological sciences has been formulated as specific implementations of the general theory of inverse problems. In this article, it is pointed out that a number of approaches met in quantum chemistry can (and should) be classified as inverse problems. Consequently, the methodology used in these approaches may be enriched by applying ideas and theorems developed within the general field of inverse problems. Several examples, including the RKR method for the construction of potential energy curves, determining parameter values in semiempirical methods, and finding external potentials for which the pertinent Schrödinger equation is exactly solvable, are discussed in detail.

The implantation of life on Mars - Feasibility and motivation

NASA Technical Reports Server (NTRS)

Haynes, Robert H.; Mckay, Christopher P.

1992-01-01

Scientific concepts are reviewed regarding the potential formation and development of a life-bearing environment on Mars, and a potential ecopoiesis scenario is given. The development of the earth's biosphere is defined, and the major assumptions related to the formation of Martian life are listed. Three basic phases are described for the life-implantation concept which include determining whether sufficient quantities of volatiles are available, engineering the warming of the planet, and implanting microbial communities if necessary. Warming the planet theoretically releases liquid H2O and produces a thick CO2 atmosphere, and the implantation of biological communities is only necessary if no indigenous microbes emerge. It is concluded that a feasibility study is required to assess the possibilities of implanting life on Mars more concretely.

Psychological Resilience among Children Affected by Parental HIV/AIDS: A Conceptual Framework

PubMed Central

Li, Xiaoming; Chi, Peilian; Sherr, Lorraine; Cluver, Lucie; Stanton, Bonita

2015-01-01

HIV-related parental illness and death have a profound and lasting impact on a child's psychosocial wellbeing, potentially compromising the child's future. In response to a paucity of theoretical and conceptual discussions regarding the development of resilience among children affected by parental HIV, we proposed a conceptual framework of psychological resilience among children affected by HIV based on critical reviews of the existing theoretical and empirical literature. Three interactive social ecological factors were proposed to promote the resilience processes and attenuate the negative impact of parental HIV on children's psychological development. Internal assets, such as cognitive capacity, motivation to adapt, coping skills, religion/spirituality, and personality, promote resilience processes. Family resources and community resources are two critical contextual factors that facilitate resilience process. Family resources contain smooth transition, functional caregivers, attachment relationship, parenting discipline. Community resources contain teacher support, peer support, adult mentors, and effective school. The implications of the conceptual framework for future research and interventions among children affected by parental HIV were discussed. PMID:26716068

Psychological Resilience among Children Affected by Parental HIV/AIDS: A Conceptual Framework.

PubMed

Li, Xiaoming; Chi, Peilian; Sherr, Lorraine; Cluver, Lucie; Stanton, Bonita

2015-01-01

HIV-related parental illness and death have a profound and lasting impact on a child's psychosocial wellbeing, potentially compromising the child's future. In response to a paucity of theoretical and conceptual discussions regarding the development of resilience among children affected by parental HIV, we proposed a conceptual framework of psychological resilience among children affected by HIV based on critical reviews of the existing theoretical and empirical literature. Three interactive social ecological factors were proposed to promote the resilience processes and attenuate the negative impact of parental HIV on children's psychological development. Internal assets, such as cognitive capacity, motivation to adapt, coping skills, religion/spirituality, and personality, promote resilience processes. Family resources and community resources are two critical contextual factors that facilitate resilience process. Family resources contain smooth transition, functional caregivers, attachment relationship, parenting discipline. Community resources contain teacher support, peer support, adult mentors, and effective school. The implications of the conceptual framework for future research and interventions among children affected by parental HIV were discussed.

Developing a Theoretical Framework Using a Nursing Perspective to Investigate Perceived Health in the "Sandwich Generation" Group.

PubMed

Oulevey Bachmann, Annie; Danuser, Brigitta; Morin, Diane

2015-10-01

Coexisting workloads from professional, household and family, and caregiving activities for frail parents expose middle-aged individuals, the so-called "Sandwich Generation", to potential health risks. Current trends suggest that this situation will continue or increase. Thus SG health promotion has become a nursing concern. Most existing research considers coexisting workloads a priori pathogenic. Most studies have examined the association of one, versus two, of these three activities with health. Few studies have used a nursing perspective. This article presents the development of a framework based on a nursing model. We integrated Siegrist's Effort-Reward Imbalance middle-range theory into "Neuman Systems Model". The latter was chosen for its salutogenic orientation, its attention to preventive nursing interventions and the opportunity it provides to simultaneously consider positive and negative perceptions of SG health and SG coexisting workloads. Finally, it facilitated a theoretical identification of health protective factors. © The Author(s) 2015.

Bridging international relations and disaster studies: the case of disaster-conflict scholarship.

PubMed

Hollis, Simon

2018-01-01

International relations and disaster studies have much to gain by thinking critically about their respective theoretical and epistemological assumptions. Yet, few studies to date have sought to assess the potential value of linking these two disciplines. This paper begins to address this shortfall by examining the relationship between disasters and conflict as a research sphere that intersects international relations and disaster studies. Through an analysis of whether or not disasters contribute to intra-national and international conflict, this paper not only provides a review of the state of the art, but also serves to invite scholars to reflect on related concepts from other fields to strengthen their own approaches to the study of disasters in an international setting. An evaluation of the conceptual and theoretical contributions of each subject area provides useful heuristics for the development of disaster-conflict scholarship and encourages alternative modes of knowledge production through interdisciplinarity. © 2018 The Author(s). Disasters © Overseas Development Institute, 2018.

Broken flow symmetry explains the dynamics of small particles in deterministic lateral displacement arrays

PubMed Central

Kim, Sung-Cheol; Wunsch, Benjamin H.; Hu, Huan; Smith, Joshua T.; Stolovitzky, Gustavo

2017-01-01

Deterministic lateral displacement (DLD) is a technique for size fractionation of particles in continuous flow that has shown great potential for biological applications. Several theoretical models have been proposed, but experimental evidence has demonstrated that a rich class of intermediate migration behavior exists, which is not predicted. We present a unified theoretical framework to infer the path of particles in the whole array on the basis of trajectories in a unit cell. This framework explains many of the unexpected particle trajectories reported and can be used to design arrays for even nanoscale particle fractionation. We performed experiments that verify these predictions and used our model to develop a condenser array that achieves full particle separation with a single fluidic input. PMID:28607075

Why feminism in public health?

PubMed

Hammarström, A

1999-12-01

The issues raised in this editorial and exemplified within a number of the studies reported in this issue indicate new directions for public health, directions which take feminist scholarship, both outside and within the medical framework, into account. The changing potential of feminist public health, as derived from the articles in this issue, can be summarised within the following issues: new research areas, positioning women as actors, development of theoretical frameworks, reflexive theory of science, interplay between sex and gender, gender-sensitive methods, diversities among women/men, pro-feminist research on men's health and using the results for change. Thus, feminist public health represents a shift towards the new public health, with holistic and multidisciplinary activities, based on theoretical pluralism, multiple perspectives and collective actions with the aim of improving the health of gender-subordinated groups.

Accurate simulations of helium pick-up experiments using a rejection-free Monte Carlo method

NASA Astrophysics Data System (ADS)

Dutra, Matthew; Hinde, Robert

2018-04-01

In this paper, we present Monte Carlo simulations of helium droplet pick-up experiments with the intention of developing a robust and accurate theoretical approach for interpreting experimental helium droplet calorimetry data. Our approach is capable of capturing the evaporative behavior of helium droplets following dopant acquisition, allowing for a more realistic description of the pick-up process. Furthermore, we circumvent the traditional assumption of bulk helium behavior by utilizing density functional calculations of the size-dependent helium droplet chemical potential. The results of this new Monte Carlo technique are compared to commonly used Poisson pick-up statistics for simulations that reflect a broad range of experimental parameters. We conclude by offering an assessment of both of these theoretical approaches in the context of our observed results.

Finite grid radius and thickness effects on retarding potential analyzer measured suprathermal electron density and temperature

NASA Technical Reports Server (NTRS)

Knudsen, William C.

1992-01-01

The effect of finite grid radius and thickness on the electron current measured by planar retarding potential analyzers (RPAs) is analyzed numerically. Depending on the plasma environment, the current is significantly reduced below that which is calculated using a theoretical equation derived for an idealized RPA having grids with infinite radius and vanishingly small thickness. A correction factor to the idealized theoretical equation is derived for the Pioneer Venus (PV) orbiter RPA (ORPA) for electron gasses consisting of one or more components obeying Maxwell statistics. The error in density and temperature of Maxwellian electron distributions previously derived from ORPA data using the theoretical expression for the idealized ORPA is evaluated by comparing the densities and temperatures derived from a sample of PV ORPA data using the theoretical expression with and without the correction factor.

Development of Pediatric Sleep Questionnaires as Diagnostic or Epidemiological Tools: A Brief Review of Do's and Don'ts

PubMed Central

Spruyt, Karen; Gozal, David

2010-01-01

Questionnaires are a useful and extensively used tool in clinical sleep medicine and in sleep research. The number of sleep questionnaires targeting the pediatric age range has tremendously increased in recent years, and with such explosion in the number of instruments, their heterogeneity has become all the more apparent. Here, we explore the theoretical and pragmatic processes required for instrument design and development, i.e., how any questionnaire, inventory, log, or diary should be created and evaluated, and also provide illustrative examples to further underline the potential pitfalls that are inherently embedded in every step of tool development. PMID:20952230

Approaches for scalable modeling and emulation of cyber systems : LDRD final report.

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

Mayo, Jackson R.; Minnich, Ronald G.; Armstrong, Robert C.

2009-09-01

The goal of this research was to combine theoretical and computational approaches to better understand the potential emergent behaviors of large-scale cyber systems, such as networks of {approx} 10{sup 6} computers. The scale and sophistication of modern computer software, hardware, and deployed networked systems have significantly exceeded the computational research community's ability to understand, model, and predict current and future behaviors. This predictive understanding, however, is critical to the development of new approaches for proactively designing new systems or enhancing existing systems with robustness to current and future cyber threats, including distributed malware such as botnets. We have developed preliminarymore » theoretical and modeling capabilities that can ultimately answer questions such as: How would we reboot the Internet if it were taken down? Can we change network protocols to make them more secure without disrupting existing Internet connectivity and traffic flow? We have begun to address these issues by developing new capabilities for understanding and modeling Internet systems at scale. Specifically, we have addressed the need for scalable network simulation by carrying out emulations of a network with {approx} 10{sup 6} virtualized operating system instances on a high-performance computing cluster - a 'virtual Internet'. We have also explored mappings between previously studied emergent behaviors of complex systems and their potential cyber counterparts. Our results provide foundational capabilities for further research toward understanding the effects of complexity in cyber systems, to allow anticipating and thwarting hackers.« less

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

Komppula, J., E-mail: jani.komppula@jyu.fi; Tarvainen, O.

A theoretical framework for power dissipation in low temperature plasmas in corona equilibrium is developed. The framework is based on fundamental conservation laws and reaction cross sections and is only weakly sensitive to plasma parameters, e.g., electron temperature and density. The theory is applied to low temperature atomic and molecular hydrogen laboratory plasmas for which the plasma heating power dissipation to photon emission, ionization, and chemical potential is calculated. The calculated photon emission is compared to recent experimental results.

[The breaking down of imaginary socio-cultural perceptions in the migration process].

PubMed

Aruj, R

1998-01-01

This is a general study of migration and of the reasons why people decide to migrate. The author develops a theoretical approach to the study of the causes of migration, which suggests that the decision to migrate is the result of a conflict which has taken place in the minds of potential migrants and their families in which traditional social and cultural values are questioned and found wanting. (ANNOTATION)

Models, Data, and War: a Critique of the Foundation for Defense Analyses.

DTIC Science & Technology

1980-03-12

scientific formulation 6 An "objective" solution 8 Analysis of a squishy problem 9 A judgmental formulation 9 A potential for distortion 11 A subjective...inextricably tied to those judgments. Different analysts, with apparently identical knowledge of a real world problem, may develop plausible formulations ...configured is a concrete theoretical statement." 2/ The formulation of a computer model--conceiving a mathematical representation of the real world

Growth, Characterization and Device Development in Monocrystalline Diamond Films

DTIC Science & Technology

1988-06-01

ABSTRACT (ContMut on reverse,*i nauar and .dnr,A, A. W, -,,,I !Cu single crystals have been grown and prepared for use as a lattice matched substrate. A...literature survey of potential substrates which are both lattice and energy matched with diamond to promote two-dimensional growth has also been...first reported high resolution lattice imaging of CVD diamond. Diamond power MESFET devices have been theoretically evaluated and found to be capable

Electronic transport in methylated fragments of DNA

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

Almeida, M. L. de; Oliveira, J. I. N.; Lima Neto, J. X.

2015-11-16

We investigate the electronic transport properties of methylated deoxyribonucleic-acid (DNA) strands, a biological system in which methyl groups are added to DNA (a major epigenetic modification in gene expression), sandwiched between two metallic platinum electrodes. Our theoretical simulations apply an effective Hamiltonian based on a tight-binding model to obtain current-voltage curves related to the non-methylated/methylated DNA strands. The results suggest potential applications in the development of novel biosensors for molecular diagnostics.

Gravity, Magnetic and Electromagnetic Gradiometry; Strategic technologies in the 21st century

NASA Astrophysics Data System (ADS)

Veryaskin, Alexey V.

2018-02-01

Gradiometry is a multidisciplinary area that combines theoretical and applied physics, ultra-low noise electronics, precision engineering, and advanced signal processing. Applications include the search for oil, gas, and mineral resources, GPS-free navigation, defence, space missions, and medical research. This book provides readers with a comprehensive introduction, history, potential applications, and current developments in relation to some of the most advanced technologies in the 21st Century.

Electronic transport in methylated fragments of DNA

NASA Astrophysics Data System (ADS)

de Almeida, M. L.; Oliveira, J. I. N.; Lima Neto, J. X.; Gomes, C. E. M.; Fulco, U. L.; Albuquerque, E. L.; Freire, V. N.; Caetano, E. W. S.; de Moura, F. A. B. F.; Lyra, M. L.

2015-11-01

We investigate the electronic transport properties of methylated deoxyribonucleic-acid (DNA) strands, a biological system in which methyl groups are added to DNA (a major epigenetic modification in gene expression), sandwiched between two metallic platinum electrodes. Our theoretical simulations apply an effective Hamiltonian based on a tight-binding model to obtain current-voltage curves related to the non-methylated/methylated DNA strands. The results suggest potential applications in the development of novel biosensors for molecular diagnostics.

Exploration of Al-Doped ZnO in Photovoltaic Thin Films

NASA Astrophysics Data System (ADS)

Ciccarino, Christopher; Sahiner, M. Alper

The electrical properties of Al doped ZnO-based thin films represent a potential advancement in the push for increasing solar cell efficiency. Doping with Aluminum will theoretically decrease resistivity of the film and therefore achieve this potential as a viable option in the P-N junction phase of photovoltaic cells. The n-type semi-conductive characteristics of the ZnO layer will theoretically be optimized with the addition of Aluminum carriers. In this study, Aluminum doping concentrations ranging from 1-3% by mass were produced, analyzed, and compared. Films were developed onto ITO coated glass using the Pulsed Laser Deposition technique. Target thickness was 250 nm and ellipsometry measurements showed uniformity and accuracy in this regard. Active dopant concentrations were determined using Hall Effect measurements. Efficiency measurements showed possible applications of this doped compound, with upwards of 7% efficiency measured, using a Keithley 2602 SourceMeter set-up. XRD scans showed highly crystalline structures, with effective Al intertwining of the hexagonal wurtzile ZnO molecular structure. This alone indicates a promising future of collaboration between these two materials.

Electrocatalytic CO2 reduction near the theoretical potential in water using Ru complex supported on carbon nanotubes

NASA Astrophysics Data System (ADS)

Sato, Shunsuke; Arai, Takeo; Morikawa, Takeshi

2018-01-01

We successfully developed a highly efficient electrode for CO2 reduction using a Ru-complex catalyst ([Ru]) supported on carbon paper coated with multi-walled carbon nanotubes (CPCNT/[Ru]). The CPCNT/[Ru] electrode promoted the CO2 reduction reaction in aqueous solution near the theoretical potential, and produced formate linearly with a current density of greater than 0.9 mA cm-2 at -0.15 V (versus RHE) for at least 24 h. Due to the outstandingly low overpotential, a monolithic tablet-shaped photo-device was realized by coupling the CPCNT/[Ru] catalyst with amorphous SiGe-jn as a light absorber and IrO x as a water oxidation catalyst, and the device produced formate from CO2 and water in a single-compartment reactor. The nanotubes enhanced the rate for CO2 reduction at [Ru], and accordingly a solar-to-chemical conversion efficiency of 4.3% for formate production was achieved when the CO2 reduction and H2O oxidation sites had the same area.

Combustion: an oil spill mitigation tool

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

None

1979-11-01

The technical feasibility of using combustion as an oil spill mitigation tool was studied. Part I of the two-part report is a practical guide oriented toward the needs of potential users, while Part II is the research or resource document from which the practical guidance was drawn. The study included theoretical evaluations of combustion of petroleum pool fires under the effects of weathering and an oil classification system related to combustion potential. The theoretical analysis of combustion is balanced by practical experience of oil burning and case history information. Decision elements are provided which can be used as a guidemore » for technical evaluations of a particular oil spill situation. The rationale for assessing technical feasibility is given in the context of other alternatives available for response to an oil spill. A series of research and technology development concepts are included for future research. The ethics of using oil burning are discussed as issues, concerns, and tradeoffs. A detailed annotated bibliography is appended along with a capsule review of a decade of oil burning studies and other support information.« less

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

Exploring 'new' bioactivities of polymers at the nano-bio interface.

PubMed

Wang, Chunming; Dong, Lei

2015-01-01

A biological system is essentially an elegant assembly of polymeric nanostructures. The polymers in the body, biomacromolecules, are both building blocks and versatile messengers. We propose that non-biologically derived polymers can be potential therapeutic candidates with unique advantages. Emerging findings about polycations, polysaccharides, immobilised multivalent ligands, and biomolecular coronas provide evidence that polymers are activated at the nano-bio interface, while emphasising the current theoretical and practical challenges. Our increasing understanding of the nano-bio interface and evolving approaches to establish the therapeutic potential of polymers enable the development of polymer drugs with high specificities for broad applications. Copyright © 2014 Elsevier Ltd. All rights reserved.

Jet engine applications for materials with nanometer-scale dimensions

NASA Technical Reports Server (NTRS)

Appleby, J. W., Jr.

1995-01-01

The performance of advanced military and commercial gas turbine engines is often linked to advances in materials technology. High performance gas turbine engines being developed require major material advances in strength, toughness, reduced density and improved temperature capability. The emerging technology of nanostructured materials has enormous potential for producing materials with significant improvements in these properties. Extraordinary properties demonstrated in the laboratory include material strengths approaching theoretical limit, ceramics that demonstrate ductility and toughness, and materials with ultra-high hardness. Nanostructured materials and coatings have the potential for meeting future gas turbine engine requirements for improved performance, reduced weight and lower fuel consumption.

Jet engine applications for materials with nanometer-scale dimensions

NASA Technical Reports Server (NTRS)

Appleby, J. W., Jr.

1995-01-01

The performance of advanced military and commercial gas turbine engines is often linked to advances in materials technology. High performance gas turbine engines being developed require major material advances in strength, toughness, reduced density and improved temperature capability. The emerging technology of nanostructured materials has enormous potential for producing materials with significant improvements in these properties. Extraordinary properties demonstrated in the laboratory include material strengths approaching theoretical limit, ceramics that demonstrate ductility and toughness, and material with ultra-high hardness. Nanostructured materials and coatings have the potential for meeting future gas turbine engine requirements for improved performance, reduced weight and lower fuel consumption.

A theoretical study of the molecular mechanism of the GAPDH Trypanosoma cruzi enzyme involving iodoacetate inhibitor

NASA Astrophysics Data System (ADS)

Carneiro, Agnaldo Silva; Lameira, Jerônimo; Alves, Cláudio Nahum

2011-10-01

The glyceraldehyde-3-phosphate dehydrogenase enzyme (GAPDH) is an important biological target for the development of new chemotherapeutic agents against Chagas disease. In this Letter, the inhibition mechanism of GAPDH involving iodoacetate (IAA) inhibitor was studied using the hybrid quantum mechanical/molecular mechanical (QM/MM) approach and molecular dynamic simulations. Analysis of the potential energy surface and potential of mean force show that the covalent attachment of IAA inhibitor to the active site of the enzyme occurs as a concerted process. In addition, the energy terms decomposition shows that NAD+ plays an important role in stabilization of the reagents and transition state.

Going ballistic: Graphene hot electron transistors

NASA Astrophysics Data System (ADS)

Vaziri, S.; Smith, A. D.; Östling, M.; Lupina, G.; Dabrowski, J.; Lippert, G.; Mehr, W.; Driussi, F.; Venica, S.; Di Lecce, V.; Gnudi, A.; König, M.; Ruhl, G.; Belete, M.; Lemme, M. C.

2015-12-01

This paper reviews the experimental and theoretical state of the art in ballistic hot electron transistors that utilize two-dimensional base contacts made from graphene, i.e. graphene base transistors (GBTs). Early performance predictions that indicated potential for THz operation still hold true today, even with improved models that take non-idealities into account. Experimental results clearly demonstrate the basic functionality, with on/off current switching over several orders of magnitude, but further developments are required to exploit the full potential of the GBT device family. In particular, interfaces between graphene and semiconductors or dielectrics are far from perfect and thus limit experimental device integrity, reliability and performance.

More similarities than differences in contemporary theories of social development?: a plea for theory bridging.

PubMed

Leaper, Campbell

2011-01-01

Many contemporary theories of social development are similar and/or share complementary constructs. Yet, there have been relatively few efforts toward theoretical integration. The present chapter represents a call for increased theory bridging. The problem of theoretical fragmentation in psychology is reviewed. Seven highlighted reasons for this predicament include differences between behavioral sciences and other sciences, theoretical paradigms as social identities, the uniqueness assumption, information overload, field fixation, linguistic fragmentation, and few incentives for theoretical integration. Afterward, the feasibility of theoretical synthesis is considered. Finally, some possible directions are proposed for theoretical integration among five contemporary theories of social and gender development: social cognitive theory, expectancy-value theory, cognitive-developmental theory, gender schema theory, and self-categorization theory.

Getting the Right Answers for the Right Reasons: Toward Predictive Molecular Simulations of Water with Many-Body Potential Energy Functions.

PubMed

Paesani, Francesco

2016-09-20

The central role played by water in fundamental processes relevant to different disciplines, including chemistry, physics, biology, materials science, geology, and climate research, cannot be overemphasized. It is thus not surprising that, since the pioneering work by Stillinger and Rahman, many theoretical and computational studies have attempted to develop a microscopic description of the unique properties of water under different thermodynamic conditions. Consequently, numerous molecular models based on either molecular mechanics or ab initio approaches have been proposed over the years. However, despite continued progress, the correct prediction of the properties of water from small gas-phase clusters to the liquid phase and ice through a single molecular model remains challenging. To large extent, this is due to the difficulties encountered in the accurate modeling of the underlying hydrogen-bond network in which both number and strength of the hydrogen bonds vary continuously as a result of a subtle interplay between energetic, entropic, and nuclear quantum effects. In the past decade, the development of efficient algorithms for correlated electronic structure calculations of small molecular complexes, accompanied by tremendous progress in the analytical representation of multidimensional potential energy surfaces, opened the doors to the design of highly accurate potential energy functions built upon rigorous representations of the many-body expansion (MBE) of the interaction energies. This Account provides a critical overview of the performance of the MB-pol many-body potential energy function through a systematic analysis of energetic, structural, thermodynamic, and dynamical properties as well as of vibrational spectra of water from the gas to the condensed phase. It is shown that MB-pol achieves unprecedented accuracy across all phases of water through a quantitative description of each individual term of the MBE, with a physically correct representation of both short- and long-range many-body contributions. Comparisons with experimental data probing different regions of the water potential energy surface from clusters to bulk demonstrate that MB-pol represents a major step toward the long-sought-after "universal model" capable of accurately describing the molecular properties of water under different conditions and in different environments. Along this path, future challenges include the extension of the many-body scheme adopted by MB-pol to the description of generic solutes as well as the integration of MB-pol in an efficient theoretical and computational framework to model acid-base reactions in aqueous environments. In this context, given the nontraditional form of the MB-pol energy and force expressions, synergistic efforts by theoretical/computational chemists/physicists and computer scientists will be critical for the development of high-performance software for many-body molecular dynamics simulations.

Development of a theoretical framework of factors affecting patient safety incident reporting: a theoretical review of the literature

PubMed Central

Hull, Louise; Soukup, Tayana; Mayer, Erik; Athanasiou, Thanos; Sevdalis, Nick; Darzi, Ara

2017-01-01

Objectives The development and implementation of incident reporting systems within healthcare continues to be a fundamental strategy to reduce preventable patient harm and improve the quality and safety of healthcare. We sought to identify factors contributing to patient safety incident reporting. Design To facilitate improvements in incident reporting, a theoretical framework, encompassing factors that act as barriers and enablers ofreporting, was developed. Embase, Ovid MEDLINE(R) and PsycINFO were searched to identify relevant articles published between January 1980 and May 2014. A comprehensive search strategy including MeSH terms and keywords was developed to identify relevant articles. Data were extracted by three independent researchers; to ensure the accuracy of data extraction, all studies eligible for inclusion were rescreened by two reviewers. Results The literature search identified 3049 potentially eligible articles; of these, 110 articles, including >29 726 participants, met the inclusion criteria. In total, 748 barriers were identified (frequency count) across the 110 articles. In comparison, 372 facilitators to incident reporting and 118 negative cases were identified. The top two barriers cited were fear of adverse consequences (161, representing 21.52% of barriers) and process and systems of reporting (110, representing 14.71% of barriers). In comparison, the top two facilitators were organisational (97, representing 26.08% of facilitators) and process and systems of reporting (75, representing 20.16% of facilitators). Conclusion A wide range of factors contributing to engagement in incident reporting exist. Efforts that address the current tendency to under-report must consider the full range of factors in order to develop interventions as well as a strategic policy approach for improvement. PMID:29284714

Development of a theoretical framework of factors affecting patient safety incident reporting: a theoretical review of the literature.

PubMed

Archer, Stephanie; Hull, Louise; Soukup, Tayana; Mayer, Erik; Athanasiou, Thanos; Sevdalis, Nick; Darzi, Ara

2017-12-27

The development and implementation of incident reporting systems within healthcare continues to be a fundamental strategy to reduce preventable patient harm and improve the quality and safety of healthcare. We sought to identify factors contributing to patient safety incident reporting. To facilitate improvements in incident reporting, a theoretical framework, encompassing factors that act as barriers and enablers ofreporting, was developed. Embase, Ovid MEDLINE(R) and PsycINFO were searched to identify relevant articles published between January 1980 and May 2014. A comprehensive search strategy including MeSH terms and keywords was developed to identify relevant articles. Data were extracted by three independent researchers; to ensure the accuracy of data extraction, all studies eligible for inclusion were rescreened by two reviewers. The literature search identified 3049 potentially eligible articles; of these, 110 articles, including >29 726 participants, met the inclusion criteria. In total, 748 barriers were identified (frequency count) across the 110 articles. In comparison, 372 facilitators to incident reporting and 118 negative cases were identified. The top two barriers cited were fear of adverse consequences (161, representing 21.52% of barriers) and process and systems of reporting (110, representing 14.71% of barriers). In comparison, the top two facilitators were organisational (97, representing 26.08% of facilitators) and process and systems of reporting (75, representing 20.16% of facilitators). A wide range of factors contributing to engagement in incident reporting exist. Efforts that address the current tendency to under-report must consider the full range of factors in order to develop interventions as well as a strategic policy approach for improvement. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Applications of High-Frequency Gravitational Waves to the Global War on Terror

NASA Astrophysics Data System (ADS)

Baker, Robert M. L.

2010-01-01

Applications of high-frequency gravitational waves or HFGWs to the global war on terror are now realistic because technology developed by GravWave® LLC and other institutions overseas can lead to devices, some already constructed, that can generate and detect HFGWs. In fact, three HFGW detectors have been built outside the United States and an ultra high-sensitive Li-Baker HFGW Detector has been proposed. HFGW generators have been proposed theoretically by the Russians, Germans, Italians and Chinese. Because of their unique characteristics, such as their ability to pass through all material without attenuation, HFGWs could be utilized for uninterruptible, very low-probability-of-intercept (LPI), high-bandwidth communications among and between anti-terrorist assets. One such communications system, which can be constructed from off-the-shelf elements, is discussed. The HFGW generation device or transmitter alternative selected is based upon bands of piezoelectric crystal, film-bulk acoustic resonators or FBARs energized by conventional Magnetrons. The system is theoretically capable of transmitting and detecting, through use of the Li-Baker HFGW detector, a signal generated on the opposite side of the Earth. Although HFGWs do not interact with and are not absorbed by ordinary matter, their presence can be detected by their distortion of spacetime as measured by the Laser Interferometer Gravitational Observatory (LIGO), Virgo, GEO600, et al., by detection photons generated from electromagnetic beams having the same frequency, direction and phase as the HFGWs in a superimposed magnetic field (Li-Baker HFGW Detector), by the change in polarization HFGWs produce in a microwave guide (Birmingham University Detector) and by other such instruments. Potential theoretical applications, which may or may not be practical yet theoretically possible, are propulsion, including "moving" space objects such as missiles, anti-missiles and warheads in flight; surveillance through buildings and the Earth itself and remote initiation of nuclear events. Such applications can only be quantified and established as practical by the proof-of-concept generation and detection of HFGWs in the laboratory experiment. These important potential HFGW applications are motivations for HFGW research and development and such an R&D program is recommended for immediate initiation.

Economic Incentives for Cybersecurity: Using Economics to Design Technologies Ready for Deployment

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

Vishik, Claire; Sheldon, Frederick T; Ott, David

Cybersecurity practice lags behind cyber technology achievements. Solutions designed to address many problems may and do exist but frequently cannot be broadly deployed due to economic constraints. Whereas security economics focuses on the cost/benefit analysis and supply/demand, we believe that more sophisticated theoretical approaches, such as economic modeling, rarely utilized, would derive greater societal benefits. Unfortunately, today technologists pursuing interesting and elegant solutions have little knowledge of the feasibility for broad deployment of their results and cannot anticipate the influences of other technologies, existing infrastructure, and technology evolution, nor bring the solutions lifecycle into the equation. Additionally, potentially viable solutionsmore » are not adopted because the risk perceptions by potential providers and users far outweighs the economic incentives to support introduction/adoption of new best practices and technologies that are not well enough defined. In some cases, there is no alignment with redominant and future business models as well as regulatory and policy requirements. This paper provides an overview of the economics of security, reviewing work that helped to define economic models for the Internet economy from the 1990s. We bring forward examples of potential use of theoretical economics in defining metrics for emerging technology areas, positioning infrastructure investment, and building real-time response capability as part of software development. These diverse examples help us understand the gaps in current research. Filling these gaps will be instrumental for defining viable economic incentives, economic policies, regulations as well as early-stage technology development approaches, that can speed up commercialization and deployment of new technologies in cybersecurity.« less

Theoretical Model of Development of Information Competence among Students Enrolled in Elective Courses

ERIC Educational Resources Information Center

Zhumasheva, Anara; Zhumabaeva, Zaida; Sakenov, Janat; Vedilina, Yelena; Zhaxylykova, Nuriya; Sekenova, Balkumis

2016-01-01

The current study focuses on the research topic of creating a theoretical model of development of information competence among students enrolled in elective courses. In order to examine specific features of the theoretical model of development of information competence among students enrolled in elective courses, we performed an analysis of…

Event-related potential response to auditory social stimuli, parent-reported social communicative deficits and autism risk in school-aged children with congenital visual impairment.

PubMed

Bathelt, Joe; Dale, Naomi; de Haan, Michelle

2017-10-01

Communication with visual signals, like facial expression, is important in early social development, but the question if these signals are necessary for typical social development remains to be addressed. The potential impact on social development of being born with no or very low levels of vision is therefore of high theoretical and clinical interest. The current study investigated event-related potential responses to basic social stimuli in a rare group of school-aged children with congenital visual disorders of the anterior visual system (globe of the eye, retina, anterior optic nerve). Early-latency event-related potential responses showed no difference between the VI and control group, suggesting similar initial auditory processing. However, the mean amplitude over central and right frontal channels between 280 and 320ms was reduced in response to own-name stimuli, but not control stimuli, in children with VI suggesting differences in social processing. Children with VI also showed an increased rate of autistic-related behaviours, pragmatic language deficits, as well as peer relationship and emotional problems on standard parent questionnaires. These findings suggest that vision may be necessary for the typical development of social processing across modalities. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Exploring uncertainty in the Earth Sciences - the potential field perspective

NASA Astrophysics Data System (ADS)

Saltus, R. W.; Blakely, R. J.

2013-12-01

Interpretation of gravity and magnetic anomalies is mathematically non-unique because multiple theoretical solutions are possible. The mathematical label of 'non-uniqueness' can lead to the erroneous impression that no single interpretation is better in a geologic sense than any other. The purpose of this talk is to present a practical perspective on the theoretical non-uniqueness of potential field interpretation in geology. There are multiple ways to approach and constrain potential field studies to produce significant, robust, and definitive results. For example, a smooth, bell-shaped gravity profile, in theory, could be caused by an infinite set of physical density bodies, ranging from a deep, compact, circular source to a shallow, smoothly varying, inverted bell-shaped source. In practice, however, we can use independent geologic or geophysical information to limit the range of possible source densities and rule out many of the theoretical solutions. We can further reduce the theoretical uncertainty by careful attention to subtle anomaly details. For example, short-wavelength anomalies are a well-known and theoretically established characteristic of shallow geologic sources. The 'non-uniqueness' of potential field studies is closely related to the more general topic of scientific uncertainty in the Earth sciences and beyond. Nearly all results in the Earth sciences are subject to significant uncertainty because problems are generally addressed with incomplete and imprecise data. The increasing need to combine results from multiple disciplines into integrated solutions in order to address complex global issues requires special attention to the appreciation and communication of uncertainty in geologic interpretation.

The Contribution of Environmental Assessment to Sustainable Development: Toward a Richer Empirical Understanding

NASA Astrophysics Data System (ADS)

Cashmore, Matthew; Bond, Alan; Cobb, Dick

2007-09-01

It has long been suggested that environmental assessment has the potential to contribute to sustainable development through mechanisms above and beyond informing design and consent decisions, and while theories have been proposed to explain how this might occur, few have been subjected to rigorous empirical validation. This research advances the theoretical debate by building a rich empirical understanding of environmental assessment’s practical outcomes, from which its potential to contribute to sustainable development can be gauged. Three case study environmental assessment processes in England were investigated using a combination of data generated from content analysis, in-depth interviews, and a questionnaire survey. Four categories of outcomes are delineated based on the research data: learning outcomes; governance outcomes; attitudinal and value changes; and developmental outcomes. The data provide a robust critique of mainstream theory, with its focus on design and consent decisions. The article concludes with an examination of the consequences of the context-specific nature of environmental assessment practices in terms of developing theory and focusing future research.

Digital image profilers for detecting faint sources which have bright companions, phase 2

NASA Technical Reports Server (NTRS)

Morris, Elena; Flint, Graham

1991-01-01

A breadboard image profiling system developed for the first phase of this project demonstrated the potential for detecting extremely faint optical sources in the presence of light companions. Experimental data derived from laboratory testing of the device supports the theory that image profilers of this type may approach the theoretical limit imposed by photon statistics. The objective of Phase 2 of this program is the development of a ground-based multichannel image profiling system capable of detecting faint stellar objects slightly displaced from brighter stars. We have finalized the multichannel image profiling system and attempted three field tests.

Asia on the move: research challenges for population geography.

PubMed

Hugo, G

1996-06-01

This paper "summarises some of the major changes which have occurred in international migration to, from, and within Asia in the last two decades....A number of theoretical challenges are put forward regarding the complex interrelationships between international population movements, economic development and social change. The employment of systems approaches, neoclassical economic theory, social networks and institutional approaches, and the potential role of population geography in developing a more comprehensive explanation of the changing dynamics of international migration in the region, are discussed. Also considered are the gender dimension in migration, remittance flows and their consequences, and policy issues." excerpt

An Integrated Study on a Novel High Temperature High Entropy Alloy

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

Yang, Shizhong

2016-12-31

This report summarizes our recent works of theoretical modeling, simulation, and experimental validation of the simulation results on the new refractory high entropy alloy (HEA) design and oxide doped refractory HEA research. The simulation of the stability and thermal dynamics simulation on potential thermal stable candidates were performed and related HEA with oxide doped samples were synthesized and characterized. The HEA ab initio density functional theory and molecular dynamics physical property simulation methods and experimental texture validation techniques development, achievements already reached, course work development, students and postdoc training, and future improvement research directions are briefly introduced.

Heat sink effects in VPPA welding

NASA Technical Reports Server (NTRS)

Steranka, Paul O., Jr.

1990-01-01

The development of a model for prediction of heat sink effects associated with the Variable Polarity Plasma Arc (VPPA) Welding Process is discussed. The long term goal of this modeling is to provide means for assessing potential heat sink effects and, eventually, to provide indications as to changes in the welding process that could be used to compensate for these effects and maintain the desired weld quality. In addition to the development of a theoretical model, a brief experimental investigation was conducted to demonstrate heat sink effects and to provide an indication of the accuracy of the model.

The relevance of traditional knowledge systems for ethnopharmacological research: theoretical and methodological contributions

PubMed Central

2010-01-01

Background Ethnopharmacology is at the intersection of the medical, natural, and social sciences. Despite its interdisciplinary nature, most ethnopharmacological research has been based on the combination of the chemical, biological, and pharmacological sciences. Far less attention has been given to the social sciences, including anthropology and the study of traditional knowledge systems. Methods I reviewed the literature on traditional knowledge systems highlighting its potential theoretical and methodological contributions to ethnopharmacology. Results I discuss three potential theoretical contributions of traditional knowledge systems to ethnopharmacological research. First, while many plants used in indigenous pharmacopoeias have active compounds, those compounds do not always act alone in indigenous healing systems. Research highlights the holistic nature of traditional knowledge systems and helps understand plant's efficacy in its cultural context. Second, research on traditional knowledge systems can improve our understanding of how ethnopharmacological knowledge is distributed in a society, and who benefits from it. Third, research on traditional knowledge systems can enhance the study of the social relations that enable the generation, maintenance, spread, and devolution of cultural traits and innovations, including ethnopharmacological knowledge. At a methodological level, some ethnopharmacologists have used anthropological tools to understand the context of plant use and local meanings of health and disease. I discuss two more potential methodological contributions of research on traditional knowledge systems to ethnopharmacological research. First, traditional knowledge systems research has developed methods that would help ethnopharmacologists understand how people classify illnesses and remedies, a fundamental aspect of folk medicinal plant selection criteria. Second, ethnopharmacologists could also borrow methods derived from cultural consensus theory to have a broader look at intracultural variation and at the analysis of transmission and loss of traditional ethnopharmacological knowledge. Conclusions Ethical considerations in the ethnopharmacology of the 21st century should go beyond the recognition of the Intellectual Property Rights or the acquisition of research permits, to include considerations on the healthcare of the original holders of ethnopharmacological knowledge. Ethnopharmacology can do more than speed up to recover the traditional knowledge of indigenous peoples to make it available for the development of new drugs. Ethnopharmacologists can work with health care providers in the developing world for the local implementation of ethnopharmacological research results. PMID:21083913

Flow through a very porous obstacle in a shallow channel

PubMed Central

Draper, S.; Nishino, T.; Borthwick, A. G. L.

2017-01-01

A theoretical model, informed by numerical simulations based on the shallow water equations, is developed to predict the flow passing through and around a uniform porous obstacle in a shallow channel, where background friction is important. This problem is relevant to a number of practical situations, including flow through aquatic vegetation, the performance of arrays of turbines in tidal channels and hydrodynamic forces on offshore structures. To demonstrate this relevance, the theoretical model is used to (i) reinterpret core flow velocities in existing laboratory-based data for an array of emergent cylinders in shallow water emulating aquatic vegetation and (ii) reassess the optimum arrangement of tidal turbines to generate power in a tidal channel. Comparison with laboratory-based data indicates a maximum obstacle resistance (or minimum porosity) for which the present theoretical model is valid. When the obstacle resistance is above this threshold the shallow water equations do not provide an adequate representation of the flow, and the theoretical model over-predicts the core flow passing through the obstacle. The second application of the model confirms that natural bed resistance increases the power extraction potential for a partial tidal fence in a shallow channel and alters the optimum arrangement of turbines within the fence. PMID:28484321

A biologically inspired artificial muscle based on fiber-reinforced and electropneumatic dielectric elastomers

NASA Astrophysics Data System (ADS)

Liu, Lei; Zhang, Chi; Luo, Meng; Chen, Xi; Li, Dichen; Chen, Hualing

2017-08-01

Dielectric elastomers (DEs) have great potential for use as artificial muscles because of the following characteristics: electrical activity, fast and large deformation under stimuli, and softness as natural muscles. Inspired by the traditional McKibben actuators, in this study, we developed a cylindrical soft fiber-reinforced and electropneumatic DE artificial muscle (DEAM) by mimicking the spindle shape of natural muscles. Based on continuum mechanics and variation principle, the inhomogeneous actuation of DEAMs was theoretically modeled and calculated. Prototypes of DEAMs were prepared to validate the design concept and theoretical model. The theoretical predictions are consistent with the experimental results; they successfully predicted the evolutions of the contours of DEAMs with voltage. A pneumatically supported high prestretch in the hoop direction was achieved by our DEAM prototype without buckling the soft fibers sandwiched by the DE films. Besides, a continuously tunable prestretch in the actuation direction was achieved by varying the supporting pressure. Using the theoretical model, the failure modes, maximum actuations, and critical voltages were analyzed; they were highly dependent on the structural parameters, i.e., the cylinder aspect ratio, prestretch level, and supporting pressure. The effects of structural parameters and supporting pressure on the actuation performance were also investigated to optimize the DEAMs.

Theoretical and observational constraints on Tachyon Inflation

NASA Astrophysics Data System (ADS)

Barbosa-Cendejas, Nandinii; De-Santiago, Josue; German, Gabriel; Hidalgo, Juan Carlos; Rigel Mora-Luna, Refugio

2018-03-01

We constrain several models in Tachyonic Inflation derived from the large-N formalism by considering theoretical aspects as well as the latest observational data. On the theoretical side, we assess the field range of our models by means of the excursion of the equivalent canonical field. On the observational side, we employ BK14+PLANCK+BAO data to perform a parameter estimation analysis as well as a Bayesian model selection to distinguish the most favoured models among all four classes here presented. We observe that the original potential V propto sech(T) is strongly disfavoured by observations with respect to a reference model with flat priors on inflationary observables. This realisation of Tachyon inflation also presents a large field range which may demand further quantum corrections. We also provide examples of potentials derived from the polynomial and the perturbative classes which are both statistically favoured and theoretically acceptable.

The Correlation between Chronic Periodontitis and Oral Cancer.

PubMed

Krüger, Maximilian; Hansen, Torsten; Kasaj, Adrian; Moergel, Maximilian

2013-01-01

Infections are increasingly considered as potential trigger for carcinogenesis apart from risk factors like alcohol and tobacco. The discussion about human papilloma virus (HPV) in oral squamous cell carcinoma (OSCC) points at a general role of infection for the development of oral carcinomas. Furthermore, first studies describe a correlation between chronic periodontitis and OSCC, thus, characterizing chronic inflammation as being a possible trigger for OSCC. In front of this background, we present four well-documented clinical cases. All patients showed a significant anatomical relation between OSCC and clinical signs of chronic periodontitis. The interindividual differences of the clinical findings lead to different theoretical concepts: two with coincidental appearance of OSCC and chronic periodontitis and two with possible de novo development of OSCC triggered by chronic inflammation. We conclude that the activation of different inflammatory cascades by chronic periodontitis negatively affects mucosa and bone. Furthermore, the inflammatory response has the potential to activate carcinogenesis. Apart from a mere coincidental occurrence, two out of four patients give first clinical hints for a model wherein chronic periodontitis represents a potential risk factor for the development of OSCC.

Two-potential approach for electron-molecular collisions at intermediate and high energies - Application to e-N2 scatterings

NASA Technical Reports Server (NTRS)

Choi, B. H.; Poe, R. T.; Sun, J. C.; Shan, Y.

1979-01-01

A general theoretical approach is proposed for the calculation of elastic, vibrational, and rotational transitions for electron-molecule scattering at intermediate and high-electron-impact energies. In this formulation, contributions to the scattering process come from the incoherent sum of two dominant potentials: a short-range shielded nuclear Coulomb potential from individual atomic centers, and a permanent/induced long-range potential. Application to e-N2 scattering from 50-500 eV incident electron energies has yielded good agreement with absolutely calibrated experiments. Comparisons with other theoretical approaches are made. The physical picture as well as the general features of electron-molecule scattering process are discussed within the framework of the two-potential approach.

The meaning of pharmacological treatment for schizophrenic patients1

PubMed Central

Vedana, Kelly Graziani Giacchero; Miasso, Adriana Inocenti

2014-01-01

OBJECTIVE: to understand the meaning of medication therapy for schizophrenic patients and formulate a theoretical model about the study phenomenon. METHOD: a qualitative approach was employed, using Symbolic Interactionism as the theoretical and Grounded Theory as the methodological framework. The research was developed between 2008 and 2010 at three community mental health services in the interior of the State of São Paulo - Brazil. Thirty-six patients and thirty-six family members were selected through theoretical sampling. The data were mainly collected through open interviews and observation and simultaneously analyzed through open, axial and selective coding. RESULTS: the meaning of the pharmacotherapy is centered on the phenomenon "Living with a help that bothers", which expresses the patients' ambivalence towards the medication and determines their decision making. The insight, access, limitations for self-administration of the drugs and interactions with family members and the health team influenced the patient's medication-related behavior. CONCLUSION: the theory presented in this study provides a comprehensive, contextualized, motivational and dynamic understanding of the relation the patient experiences and indicates potentials and barriers to follow the medication treatment. PMID:25296152

Constrained orbital intercept-evasion

NASA Astrophysics Data System (ADS)

Zatezalo, Aleksandar; Stipanovic, Dusan M.; Mehra, Raman K.; Pham, Khanh

2014-06-01

An effective characterization of intercept-evasion confrontations in various space environments and a derivation of corresponding solutions considering a variety of real-world constraints are daunting theoretical and practical challenges. Current and future space-based platforms have to simultaneously operate as components of satellite formations and/or systems and at the same time, have a capability to evade potential collisions with other maneuver constrained space objects. In this article, we formulate and numerically approximate solutions of a Low Earth Orbit (LEO) intercept-maneuver problem in terms of game-theoretic capture-evasion guaranteed strategies. The space intercept-evasion approach is based on Liapunov methodology that has been successfully implemented in a number of air and ground based multi-player multi-goal game/control applications. The corresponding numerical algorithms are derived using computationally efficient and orbital propagator independent methods that are previously developed for Space Situational Awareness (SSA). This game theoretical but at the same time robust and practical approach is demonstrated on a realistic LEO scenario using existing Two Line Element (TLE) sets and Simplified General Perturbation-4 (SGP-4) propagator.

[Children and adolescents in street situation: contributions to an understanding of vulnerability and disaffiliation].

PubMed

Gontijo, Daniela; Medeiros, Marcelo

2009-01-01

The concept of vulnerability is being discussed in the public health area as a potential tool toward the transformation of the health practices for allowing an articulation individual-community. Understanding health as a process of subjectivation determined by social, cultural and historical contexts, this article aims to approach the question children and adolescents in street situation on the basis of the concept of civil vulnerability, using the theoretical background presented by Robert Castel. This author understands the social marginalization lived by different individuals and social groups in a dynamic form, determined by the association of work and social insertion. As refers to children and adolescents in street situation, we believe that they are reflecting a process of intensified vulnerability (culminating in disaffiliation) to which thousands of Brazilian families are subject due to the extreme social inequalities in our country. We hope that our theoretical discussion will be able to contribute to the development of a theoretical reference in public health and to the planning and implementation of health actions directed to this population.

Improved Processes to Remove Naphthenic Acids

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

Aihua Zhang; Qisheng Ma; Kangshi Wang

2005-12-09

In the past three years, we followed the work plan as we suggested in the proposal and made every efforts to fulfill the project objectives. Based on our large amount of creative and productive work, including both of experimental and theoretic aspects, we received important technical breakthrough on naphthenic acid removal process and obtained deep insight on catalytic decarboxylation chemistry. In detail, we established an integrated methodology to serve for all of the experimental and theoretical work. Our experimental investigation results in discovery of four type effective catalysts to the reaction of decarboxylation of model carboxylic acid compounds. The adsorptionmore » experiment revealed the effectiveness of several solid materials to naphthenic acid adsorption and acidity reduction of crude oil, which can be either natural minerals or synthesized materials. The test with crude oil also received promising results, which can be potentially developed into a practical process for oil industry. The theoretical work predicted several possible catalytic decarboxylation mechanisms that would govern the decarboxylation pathways depending on the type of catalysts being used. The calculation for reaction activation energy was in good agreement with our experimental measurements.« less

Shape control of NITINOL-reinforced composite beams

NASA Astrophysics Data System (ADS)

Baz, Amr M.; Chen, Tung-Huei; Ro, Jeng-Jong

1994-05-01

The shape of composite beams is controlled by sets of flat strips of a shape memory nickel-titanium alloy (NITINOL). A mathematical model is developed to describe the behavior of this class of SMART composites. The model describes the interaction between the elastic characteristics of the composite beams and the thermally- induced shape memory effect of the NITINOL strips. The effect of various activation strategies of the NITINOL strips on the shape of the composite beams is determined. The theoretical predictions of the model are validated experimentally using a fiberglass composite beam made of 8 plies of unidirectional BASF 5216 prepregs which are 9.75-cm wide and 21.20 cm long. The beams are provided with four NITINOL-55 strips which are 1.2 mm thick and 1.25 cm wide. The time response characteristics of the beam are monitored and compared with the corresponding theoretical characteristics. Close agreement is obtained between the theoretical predictions and the experimental results. The obtained results suggest the potential of the NITINOL strips in controlling the shape of composite beams without compromising their structural stiffness.

The meaning of pharmacological treatment for schizophrenic patients.

PubMed

Vedana, Kelly Graziani Giacchero; Miasso, Adriana Inocenti

2014-01-01

to understand the meaning of medication therapy for schizophrenic patients and formulate a theoretical model about the study phenomenon. a qualitative approach was employed, using Symbolic Interactionism as the theoretical and Grounded Theory as the methodological framework. The research was developed between 2008 and 2010 at three community mental health services in the interior of the State of São Paulo - Brazil. Thirty-six patients and thirty-six family members were selected through theoretical sampling. The data were mainly collected through open interviews and observation and simultaneously analyzed through open, axial and selective coding. the meaning of the pharmacotherapy is centered on the phenomenon "Living with a help that bothers", which expresses the patients' ambivalence towards the medication and determines their decision making. The insight, access, limitations for self-administration of the drugs and interactions with family members and the health team influenced the patient's medication-related behavior. the theory presented in this study provides a comprehensive, contextualized, motivational and dynamic understanding of the relation the patient experiences and indicates potentials and barriers to follow the medication treatment.

A theory-informed approach to developing visually mediated interventions to change behaviour using an asthma and physical activity intervention exemplar.

PubMed

Murray, Jennifer; Williams, Brian; Hoskins, Gaylor; Skar, Silje; McGhee, John; Treweek, Shaun; Sniehotta, Falko F; Sheikh, Aziz; Brown, Gordon; Hagen, Suzanne; Cameron, Linda; Jones, Claire; Gauld, Dylan

2016-01-01

Visualisation techniques are used in a range of healthcare interventions. However, these frequently lack a coherent rationale or clear theoretical basis. This lack of definition and explicit targeting of the underlying mechanisms may impede the success of and evaluation of the intervention. We describe the theoretical development, deployment, and pilot evaluation, of a complex visually mediated behavioural intervention. The exemplar intervention focused on increasing physical activity among young people with asthma. We employed an explicit five-stage development model, which was actively supported by a consultative user group. The developmental stages involved establishing the theoretical basis, establishing a narrative structure, visual rendering, checking interpretation, and pilot testing. We conducted in-depth interviews and focus groups during early development and checking, followed by an online experiment for pilot testing. A total of 91 individuals, including young people with asthma, parents, teachers, and health professionals, were involved in development and testing. Our final intervention consisted of two components: (1) an interactive 3D computer animation to create intentions and (2) an action plan and volitional help sheet to promote the translation of intentions to behaviour. Theory was mediated throughout by visual and audio forms. The intervention was regarded as highly acceptable, engaging, and meaningful by all stakeholders. The perceived impact on asthma understanding and intentions was reported positively, with most individuals saying that the 3D computer animation had either clarified a range of issues or made them more real. Our five-stage model underpinned by extensive consultation worked well and is presented as a framework to support explicit decision-making for others developing theory informed visually mediated interventions. We have demonstrated the ability to develop theory-based visually mediated behavioural interventions. However, attention needs to be paid to the potential ambiguity associated with images and thus the concept of visual literacy among patients. Our revised model may be helpful as a guide to aid development, acceptability, and ultimately effectiveness.

Development of a Theoretical Model to Assess the Hepatocarcinogenic Potential of Chemicals Using Structure-Activity Relationships and the Rat Hepatocyte Assay

DTIC Science & Technology

1985-11-01

Kappus ,19a5; Tyson and Green, in press). When ethane evolution was quantitated, the experimental conditions were modified to maximize sensitivity, as...commonly used and convenient technique for tVat purpose ( Kappus , 1985). Since MDA, the lipid breakdown product that the TBA reaction primarily...cytcchrome P-450(c) reductase. Mol. Pharmacol. 20, 669-673 (1981). Kappus , H. (1985). Lipid peroxidatioa: mechanisms, analysis, enzymology and

The Adsorption of Bromide Ion at Mercury from Propylene Carbonate Solutions of Constant Ionic Strength

DTIC Science & Technology

1991-05-20

Chemistry University of California Davis, CA 95616 * To whom correspondence should be addressed. t Permanent address: Instituto de Fisica e Quimica ...I]. In the case of Br- ion adsorption at Hg, studies have been carried out in water [2-4] and N- methylformamide solutions [5,6] of both varying and...discussed with respect to current theoretical developments. 4 Experimental Differential capacity against potential data were obtained for the mercury

From ab Initio Potential Energy Surfaces to State-Resolved Reactivities: X + H 2O ↔ HX + OH [X = F, Cl, and O( 3P)] Reactions

DOE PAGES

Li, Jun; Jiang, Bin; Song, Hongwei; ...

2015-04-17

Here, we survey the recent advances in theoretical understanding of quantum state resolved dynamics, using the title reactions as examples. It is shown that the progress was made possible by major developments in two areas. First, an accurate analytical representation of many high-level ab initio points over a large configuration space can now be made with high fidelity and the necessary permutation symmetry. The resulting full-dimensional global potential energy surfaces enable dynamical calculations using either quasi-classical trajectory or more importantly quantum mechanical methods. The second advance is the development of accurate and efficient quantum dynamical methods, which are necessary formore » providing a reliable treatment of quantum effects in reaction dynamics such as tunneling, resonances, and zero-point energy. The powerful combination of the two advances has allowed us to achieve a quantitatively accurate characterization of the reaction dynamics, which unveiled rich dynamical features such as steric steering, strong mode specificity, and bond selectivity. The dependence of reactivity on reactant modes can be rationalized by the recently proposed sudden vector projection model, which attributes the mode specificity and bond selectivity to the coupling of reactant modes with the reaction coordinate at the relevant transition state. The deeper insights provided by these theoretical studies have advanced our understanding of reaction dynamics to a new level.« less

Induction of Chirality in Two-Dimensional Nanomaterials: Chiral 2D MoS2 Nanostructures.

PubMed

Purcell-Milton, Finn; McKenna, Robert; Brennan, Lorcan J; Cullen, Conor P; Guillemeney, Lilian; Tepliakov, Nikita V; Baimuratov, Anvar S; Rukhlenko, Ivan D; Perova, Tatiana S; Duesberg, Georg S; Baranov, Alexander V; Fedorov, Anatoly V; Gun'ko, Yurii K

2018-02-27

Two-dimensional (2D) nanomaterials have been intensively investigated due to their interesting properties and range of potential applications. Although most research has focused on graphene, atomic layered transition metal dichalcogenides (TMDs) and particularly MoS 2 have gathered much deserved attention recently. Here, we report the induction of chirality into 2D chiral nanomaterials by carrying out liquid exfoliation of MoS 2 in the presence of chiral ligands (cysteine and penicillamine) in water. This processing resulted in exfoliated chiral 2D MoS 2 nanosheets showing strong circular dichroism signals, which were far past the onset of the original chiral ligand signals. Using theoretical modeling, we demonstrated that the chiral nature of MoS 2 nanosheets is related to the presence of chiral ligands causing preferential folding of the MoS 2 sheets. There was an excellent match between the theoretically calculated and experimental spectra. We believe that, due to their high aspect ratio planar morphology, chiral 2D nanomaterials could offer great opportunities for the development of chiroptical sensors, materials, and devices for valleytronics and other potential applications. In addition, chirality plays a key role in many chemical and biological systems, with chiral molecules and materials critical for the further development of biopharmaceuticals and fine chemicals, and this research therefore should have a strong impact on relevant areas of science and technology such as nanobiotechnology, nanomedicine, and nanotoxicology.

Remote sensing of earth terrain

NASA Technical Reports Server (NTRS)

Yueh, Herng-Aung; Kong, Jin AU

1991-01-01

In remote sensing, the encountered geophysical media such as agricultural canopy, forest, snow, or ice are inhomogeneous and contain scatters in a random manner. Furthermore, weather conditions such as fog, mist, or snow cover can intervene the electromagnetic observation of the remotely sensed media. In the modelling of such media accounting for the weather effects, a multi-layer random medium model has been developed. The scattering effects of the random media are described by three-dimensional correlation functions with variances and correlation lengths corresponding to the fluctuation strengths and the physical geometry of the inhomogeneities, respectively. With proper consideration of the dyadic Green's function and its singularities, the strong fluctuation theory is used to calculate the effective permittivities which account for the modification of the wave speed and attenuation in the presence of the scatters. The distorted Born approximation is then applied to obtain the correlations of the scattered fields. From the correlation of the scattered field, calculated is the complete set of scattering coefficients for polarimetric radar observation or brightness temperature in passive radiometer applications. In the remote sensing of terrestrial ecosystems, the development of microwave remote sensing technology and the potential of SAR to measure vegetation structure and biomass have increased effort to conduct experimental and theoretical researches on the interactions between microwave and vegetation canopies. The overall objective is to develop inversion algorithms to retrieve biophysical parameters from radar data. In this perspective, theoretical models and experimental data are methodically interconnected in the following manner: Due to the complexity of the interactions involved, all theoretical models have limited domains of validity; the proposed solution is to use theoretical models, which is validated by experiments, to establish the region in which the radar response is most sensitive to the parameters of interest; theoretically simulated data will be used to generate simple invertible models over the region. For applications to the remote sensing of sea ice, the developed theoretical models need to be tested with experimental measurements. With measured ground truth such as ice thickness, temperature, salinity, and structure, input parameters to the theoretical models can be obtained to calculate the polarimetric scattering coefficients for radars or brightness temperature for radiometers and then compare theoretical results with experimental data. Validated models will play an important role in the interpretation and classification of ice in monitoring global ice cover from space borne remote sensors in the future. We present an inversion algorithm based on a recently developed inversion method referred to as the Renormalized Source-Type Integral Equation approach. The objective of this method is to overcome some of the limitations and difficulties of the iterative Born technique. It recasts the inversion, which is nonlinear in nature, in terms of the solution of a set of linear equations; however, the final inversion equation is still nonlinear. The derived inversion equation is an exact equation which sums up the iterative Neuman (or Born) series in a closed form and, thus, is a valid representation even in the case when the Born series diverges; hence, the name Renormalized Source-Type Integral Equation Approach.

Nanostructured Materials Developed for Solar Cells

NASA Technical Reports Server (NTRS)

Bailey, Sheila G.; Castro, Stephanie L.; Raffaelle, Ryne P.; Fahey, Stephen D.; Gennett, Thomas; Tin, Padetha

2004-01-01

There has been considerable investigation recently regarding the potential for the use of nanomaterials and nanostructures to increase the efficiency of photovoltaic devices. Efforts at the NASA Glenn Research Center have involved the development and use of quantum dots and carbon nanotubes to enhance inorganic and organic cell efficiencies. Theoretical results have shown that a photovoltaic device with a single intermediate band of states resulting from the introduction of quantum dots offers a potential efficiency of 63.2 percent. A recent publication extended the intermediate band theory to two intermediate bands and calculated a limiting efficiency of 71.7 percent. The enhanced efficiency results from converting photons of energy less than the band gap of the cell by an intermediate band. The intermediate band provides a mechanism for low-energy photons to excite carriers across the energy gap by a two-step process.

Evaluation of charge mobility in organic materials: from localized to delocalized descriptions at a first-principles level.

PubMed

Shuai, Zhigang; Wang, Linjun; Li, Qikai

2011-03-04

The carrier mobility for carbon electronic materials is an important parameter for optoelectronics. We report here some recently developed theoretical tools to predict the mobility without any free parameters. Carrier scatterings with phonons and traps are the key factors in evaluating the mobility. We consider three major scattering regimes: i) where the molecular internal vibration severely induces charge self-trapping and, thus, the hopping mechanism dominates; ii) where both intermolecular and intramolecular scatterings come to play roles, so the Holstein-Peierls polaron model is applied; and, iii) where charge is well delocalized with coherence length comparable with acoustic phonon wavelength, so that a deformation potential approach is more appropriate. We develop computational methods at the first-principles level for the three different cases that have extensive potential application in rationalizing material design.

Renewable power production in a Pan-Caribbean energy grid

NASA Astrophysics Data System (ADS)

Miller, David

The Small Island Developing States of the Caribbean are victims of geography and geopolitics. Lacking access to large fossil fuel reserves, they are forced to import fuel at prices they have no control over. Renewable energy resources, particularly wind, have the potential to help break the Caribbean dependency on fossil fuels and allow for increased development at the same time. Working from a sustainable development point of view, this project discusses the history of the area, the theoretical background for the idea of large scale renewable power production, the regional initiatives already in place that address both the cost of fossil fuels and the policy hurdles that need to be overcome to assist the region in gaining energy independence. Haiti is highlighted as a special case in the region and the potential use of several renewable resources are discussed, along with a potential business model based on the idea of the Internet. Power storage is covered, specifically the potential of battery operated vehicles to have a positive impact on the Caribbean region and other developing states. The role of government regulation and policy comes into play next, followed by a discussion on the need for developed states to change patterns of behavior in order to achieve sustainability. Finally, nuclear power and liquefied natural gas are reviewed and rejected as power options for the region.

Symbolic interactionism and nurse-mother communication in the neonatal intensive care unit.

PubMed

Cleveland, Lisa Marie

2009-01-01

The admission of an infant to the neonatal intensive care unit (NICU) has the potential to cause significant stress for the mothers of these infants. Researchers have found that nurse-mother communication has the potential to either aid or hinder the mother's adaptation to the NICU environment. These communication patterns are relatively complex in nature and therefore warrant further investigation. Symbolic interactionism (SI) is a theoretical framework that offers the potential to direct such an investigation. The purpose of this article is to examine nurse-mother communication patterns in the NICU through the theoretical lens of SI.

A benchmark for reaction coordinates in the transition path ensemble

PubMed Central

2016-01-01

The molecular mechanism of a reaction is embedded in its transition path ensemble, the complete collection of reactive trajectories. Utilizing the information in the transition path ensemble alone, we developed a novel metric, which we termed the emergent potential energy, for distinguishing reaction coordinates from the bath modes. The emergent potential energy can be understood as the average energy cost for making a displacement of a coordinate in the transition path ensemble. Where displacing a bath mode invokes essentially no cost, it costs significantly to move the reaction coordinate. Based on some general assumptions of the behaviors of reaction and bath coordinates in the transition path ensemble, we proved theoretically with statistical mechanics that the emergent potential energy could serve as a benchmark of reaction coordinates and demonstrated its effectiveness by applying it to a prototypical system of biomolecular dynamics. Using the emergent potential energy as guidance, we developed a committor-free and intuition-independent method for identifying reaction coordinates in complex systems. We expect this method to be applicable to a wide range of reaction processes in complex biomolecular systems. PMID:27059559

A theoretical study of the application of jet flap circulation control for reduction of rotor vibratory forces

NASA Technical Reports Server (NTRS)

Piziali, R. A.; Trenka, A. R.

1974-01-01

The results of a study to investigate the theoretical potential of a jet-flap control system for reducing the vertical and horizontal non-cancelling helicopter rotor blade root shears are presented. A computer simulation describing the jet-flap control rotor system was developed to examine the reduction of each harmonic of the transmitted shears as a function of various rotor and jet parameters, rotor operating conditions and rotor configurations. The computer simulation of the air-loads included the influences of nonuniform inflow and blade elastic motions. (no hub motions were allowed.) The rotor trim and total rotor power (including jet compressor power) were also determined. It was found that all harmonics of the transmitted horizontal and vertical shears could be suppressed simultaneously using a single jet control.

Ion dynamics in the Venus ionosphere

NASA Astrophysics Data System (ADS)

Miller, K. L.; Whitten, R. C.

1991-02-01

Measurement data on the ion velocity in the Venus ionosphere (mainly from the Pioneer Venus Orbiter Retarding Potential Analyzer) are summarized, and theoretical models developed to explain them are reviewed. Data and theoretical predictions are compared in extensive graphs and diagrams and discussed in detail. It is shown that the predominant flow is away from the subsolar point, at up to 3 km/sec in the terminator region. A model of axisymmetric flow based on momentum, energy, and mass conservation laws is found to reproduce the observed ion velocities at solar zenith angles less than about 140 deg, but not the high velocities and chaotic behavior seen near the antisolar point. Also discussed are significant differences between the flow above and below about 400 km and the effects of changes in the dynamic pressure of the solar wind.

Remote sensing of chlorophyll concentration: State-of-the-art, 1975

NASA Technical Reports Server (NTRS)

Atwell, B. H.

1976-01-01

Remote measurement of chlorophyll concentration of the world's oceans from satellite observations could potentially be extremely useful for assessments of productivity in large areas for which measurements by other means would be impractical. The basis of these measurements rests with the physics of the interaction of light with material dissolved and suspended in the water. It is theoretically possible to predict the nature of light upwelled from the ocean surface from a solution to the radiative transfer equation. Practically, however, this is difficult. Monte-Carlo methods presently are thought to be the most viable method to treat the general theoretical problem. With restrictive assumptions of the nature of scattering, it is possible to construct simpler models. Algorithms developed to relate chlorophyll concentration (or some other parameter, i.e., seechi depth) to the upwelled light spectrum are discussed.

Research on theoretical optimization and experimental verification of minimum resistance hull form based on Rankine source method

NASA Astrophysics Data System (ADS)

Zhang, Bao-Ji; Zhang, Zhu-Xin

2015-09-01

To obtain low resistance and high efficiency energy-saving ship, minimum total resistance hull form design method is studied based on potential flow theory of wave-making resistance and considering the effects of tail viscous separation. With the sum of wave resistance and viscous resistance as objective functions and the parameters of B-Spline function as design variables, mathematical models are built using Nonlinear Programming Method (NLP) ensuring the basic limit of displacement and considering rear viscous separation. We develop ship lines optimization procedures with intellectual property rights. Series60 is used as parent ship in optimization design to obtain improved ship (Series60-1) theoretically. Then drag tests for the improved ship (Series60-1) is made to get the actual minimum total resistance hull form.

Dynamic of cold-atom tips in anharmonic potentials

PubMed Central

Menold, Tobias; Federsel, Peter; Rogulj, Carola; Hölscher, Hendrik; Fortágh, József

2016-01-01

Background: Understanding the dynamics of ultracold quantum gases in an anharmonic potential is essential for applications in the new field of cold-atom scanning probe microscopy. Therein, cold atomic ensembles are used as sensitive probe tips to investigate nanostructured surfaces and surface-near potentials, which typically cause anharmonic tip motion. Results: Besides a theoretical description of this anharmonic tip motion, we introduce a novel method for detecting the cold-atom tip dynamics in situ and real time. In agreement with theory, the first measurements show that particle interactions and anharmonic motion have a significant impact on the tip dynamics. Conclusion: Our findings will be crucial for the realization of high-sensitivity force spectroscopy with cold-atom tips and could possibly allow for the development of advanced spectroscopic techniques such as Q-control. PMID:28144505

Molecular-dynamics study of solid-liquid interface migration in fcc metals

NASA Astrophysics Data System (ADS)

Mendelev, M. I.; Rahman, M. J.; Hoyt, J. J.; Asta, M.

2010-10-01

In order to establish a link between various structural and kinetic properties of metals and the crystal-melt interfacial mobility, free-solidification molecular-dynamics simulations have been performed for a total of nine embedded atom method interatomic potentials describing pure Al, Cu and Ni. To fully explore the space of materials properties three new potentials have been developed. The new potentials are based on a previous description of Al, but in each case the liquid structure, the melting point and/or the latent heat are varied considerably. The kinetic coefficient, μ, for all systems has been compared with several theoretical predictions. It is found that at temperatures close to the melting point the magnitude of μ correlates well with the value of the diffusion coefficient in the liquid.

Explicit polarization (X-Pol) potential using ab initio molecular orbital theory and density functional theory.

PubMed

Song, Lingchun; Han, Jaebeom; Lin, Yen-lin; Xie, Wangshen; Gao, Jiali

2009-10-29

The explicit polarization (X-Pol) method has been examined using ab initio molecular orbital theory and density functional theory. The X-Pol potential was designed to provide a novel theoretical framework for developing next-generation force fields for biomolecular simulations. Importantly, the X-Pol potential is a general method, which can be employed with any level of electronic structure theory. The present study illustrates the implementation of the X-Pol method using ab initio Hartree-Fock theory and hybrid density functional theory. The computational results are illustrated by considering a set of bimolecular complexes of small organic molecules and ions with water. The computed interaction energies and hydrogen bond geometries are in good accord with CCSD(T) calculations and B3LYP/aug-cc-pVDZ optimizations.

Role of electrostatic interactions during protein ultrafiltration.

PubMed

Rohani, Mahsa M; Zydney, Andrew L

2010-10-15

A number of studies over the last decade have clearly demonstrated the importance of electrostatic interactions on the transport of charged proteins through semipermeable ultrafiltration membranes. This paper provides a review of recent developments in this field with a focus on the role of both protein and membrane charge on the rate of protein transport. Experimental results are analyzed using available theoretical models developed from the solution of the Poisson-Boltzmann equation for the partitioning of a charged particle into a charged pore. The potential of exploiting these electrostatic interactions for selective protein separations and for the development of ultrafiltration membranes with enhanced performance characteristics is also examined. Copyright © 2010 Elsevier B.V. All rights reserved.

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.

Gas-fired duplex free-piston Stirling refrigerator

NASA Astrophysics Data System (ADS)

Urieli, L.

1984-03-01

The duplex free-piston Stirling refrigerator is a potentially high efficiency, high reliability device which is ideally suited to the home appliance field, in particular as a gas-fired refrigerator. It has significant advantages over other equivalent devices including freedom from halogenated hydrocarbons, extremely low temperatures available at a high efficiency, integrated water heating, and simple burner system control. The design and development of a portable working demonstration gas-fired duplex Stirling refrigeration unit is described. A unique combination of computer aided development and experimental development was used, enabling a continued interaction between the theoretical analysis and practical testing and evaluation. A universal test rig was developed in order to separately test and evaluate major subunits, enabling a smooth system integration phase.

Review of sonic fatigue technology

NASA Technical Reports Server (NTRS)

Clarkson, B. L.

1994-01-01

From the early-1960s until the mid-1980s, there was very little theoretical development for sonic fatigue prediction. Design nomographs based on simple theoretical models and results of specially designed tests were developed for most common aircraft structures. The use of advanced composites in the 1980s, however, generated an increased interest in development of more sophisticated theoretical models because of the possibilities for a much wider range of structural designs. The purpose of this report is to review sonic fatigue technology and, in particular, to assess recent developments. It also suggests a plan for a coordinated program of theoretical and experimental work to meet the anticipated needs of future aerospace vehicles.

Using grounded theory methodology to conceptualize the mother-infant communication dynamic: potential application to compliance with infant feeding recommendations.

PubMed

Waller, Jennifer; Bower, Katherine M; Spence, Marsha; Kavanagh, Katherine F

2015-10-01

Excessive, rapid weight gain in early infancy has been linked to risk of later overweight and obesity. Inappropriate infant feeding practices associated with this rapid weight gain are currently of great interest. Understanding the origin of these practices may increase the effectiveness of interventions. Low-income populations in the Southeastern United States are at increased risk for development of inappropriate infant feeding practices, secondary to the relatively low rates of breastfeeding reported from this region. The objective was to use grounded theory methodology (GTM) to explore interactions between mothers and infants that may influence development of feeding practices, and to do so among low-income, primiparous, Southeastern United States mothers. Analysis of 15 in-depth phone interviews resulted in development of a theoretical model in which Mother-Infant Communication Dynamic emerged as the central concept. The central concept suggests a communication pattern developed over the first year of life, based on a positive feedback loop, which is harmonious and results in the maternal perception of mother and infant now speaking the same language. Importantly, though harmonious, this dynamic may result from inaccurate maternal interpretation of infant cues and behaviours, subsequently leading to inappropriate infant feeding practices. Future research should test this theoretical model using direct observation of mother-infant communication, to increase the understanding of maternal interpretation of infant cues. Subsequently, interventions targeting accurate maternal interpretation of and response to infant cues, and impact on rate of infant weight gain could be tested. If effective, health care providers could potentially use these concepts to attenuate excess rapid infant weight gain. © 2013 John Wiley & Sons Ltd.

Agent-Centric Approach for Cybersecurity Decision-Support with Partial Observability

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

Tipireddy, Ramakrishna; Chatterjee, Samrat; Paulson, Patrick R.

Generating automated cyber resilience policies for real-world settings is a challenging research problem that must account for uncertainties in system state over time and dynamics between attackers and defenders. In addition to understanding attacker and defender motives and tools, and identifying “relevant” system and attack data, it is also critical to develop rigorous mathematical formulations representing the defender’s decision-support problem under uncertainty. Game-theoretic approaches involving cyber resource allocation optimization with Markov decision processes (MDP) have been previously proposed in the literature. Moreover, advancements in reinforcement learning approaches have motivated the development of partially observable stochastic games (POSGs) in various multi-agentmore » problem domains with partial information. Recent advances in cyber-system state space modeling have also generated interest in potential applicability of POSGs for cybersecurity. However, as is the case in strategic card games such as poker, research challenges using game-theoretic approaches for practical cyber defense applications include: 1) solving for equilibrium and designing efficient algorithms for large-scale, general problems; 2) establishing mathematical guarantees that equilibrium exists; 3) handling possible existence of multiple equilibria; and 4) exploitation of opponent weaknesses. Inspired by advances in solving strategic card games while acknowledging practical challenges associated with the use of game-theoretic approaches in cyber settings, this paper proposes an agent-centric approach for cybersecurity decision-support with partial system state observability.« less

A theoretical framework for measuring knowledge in screening decision aid trials.

PubMed

Smith, Sian K; Barratt, Alexandra; Trevena, Lyndal; Simpson, Judy M; Jansen, Jesse; McCaffery, Kirsten J

2012-11-01

To describe a theoretical framework for assessing knowledge about the possible outcomes of participating in bowel cancer screening for the faecal occult blood test. The content of the knowledge measure was based on the UK General Medical Council's screening guidelines and a theory-based approach to assessing gist knowledge (Fuzzy Trace Theory). It comprised conceptual and numeric questions to assess knowledge of the underlying construct (e.g. false positive concept) and the approximate numbers affected (e.g. likelihood of a false positive). The measure was used in a randomised controlled trial involving 530 adults with low education, to compare the impact of a bowel screening decision aid with a screening information booklet developed for the Australian Government National Bowel Cancer Screening Program. The numeric knowledge scale was particularly responsive to the effects of the decision aid; at follow-up decision aid participants' numeric knowledge was significantly greater than the controls (P<0.001). This contrasts with the conceptual knowledge scale which improved significantly in both groups from baseline to follow-up (P<0.001). Our theory-based knowledge measure was responsive to change in conceptual knowledge and to the effect on numeric knowledge of a decision aid. This theoretical framework has the potential to guide the development of knowledge measures in other screening settings. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Can Inhibitors of Snake Venom Phospholipases A₂ Lead to New Insights into Anti-Inflammatory Therapy in Humans? A Theoretical Study.

PubMed

Sales, Thaís A; Marcussi, Silvana; da Cunha, Elaine F F; Kuca, Kamil; Ramalho, Teodorico C

2017-10-25

Human phospholipase A₂ ( h PLA₂) of the IIA group (HGIIA) catalyzes the hydrolysis of membrane phospholipids, producing arachidonic acid and originating potent inflammatory mediators. Therefore, molecules that can inhibit this enzyme are a source of potential anti-inflammatory drugs, with different action mechanisms of known anti-inflammatory agents. For the study and development of new anti-inflammatory drugs with this action mechanism, snake venom PLA₂ ( sv PLA₂) can be employed, since the sv PLA₂ has high similarity with the human PLA₂ HGIIA. Despite the high similarity between these secretory PLA₂s , it is still not clear if these toxins can really be employed as an experimental model to predict the interactions that occur with the human PLA₂ HGIIA and its inhibitors. Thus, the present study aims to compare and evaluate, by means of theoretical calculations, docking and molecular dynamics simulations, as well as experimental studies, the interactions of human PLA₂ HGIIA and two sv PLA₂s , Bothrops toxin II and Crotoxin B (BthTX-II and CB, respectively). Our theoretical findings corroborate experimental data and point out that the human PLA₂ HGIIA and sv PLA₂ BthTX-II lead to similar interactions with the studied compounds. From our results, the sv PLA₂ BthTX-II can be used as an experimental model for the development of anti-inflammatory drugs for therapy in humans.

Study of the high-pressure helium phase diagram using molecular dynamics

NASA Astrophysics Data System (ADS)

Koci, L.; Ahuja, R.; Belonoshko, A. B.; Johansson, B.

2007-01-01

The rich occurrence of helium and hydrogen in space makes their properties highly interesting. By means of molecular dynamics (MD), we have examined two interatomic potentials for 4He. Both potentials are demonstrated to reproduce high-pressure solid and liquid equation of state (EOS) data. The EOS, solid-solid transitions and melting at high pressures (P) were studied using a two-phase method. The Buckingham potential shows a good agreement with theoretical and experimental EOS, but does not reproduce experimental melting data. The Aziz potential shows a perfect match with theoretical melting data. We conclude that there is a stable body-centred-cubic (bcc) phase for 4He at temperatures (T) above 340 K and pressures above 22 GPa for the Buckingham potential, whereas no bcc phase is found for the Aziz potential in the applied PT range.

Theoretical foundations of the sound analog membrane potential that underlies coincidence detection in the barn owl

PubMed Central

Ashida, Go; Funabiki, Kazuo; Carr, Catherine E.

2013-01-01

A wide variety of neurons encode temporal information via phase-locked spikes. In the avian auditory brainstem, neurons in the cochlear nucleus magnocellularis (NM) send phase-locked synaptic inputs to coincidence detector neurons in the nucleus laminaris (NL) that mediate sound localization. Previous modeling studies suggested that converging phase-locked synaptic inputs may give rise to a periodic oscillation in the membrane potential of their target neuron. Recent physiological recordings in vivo revealed that owl NL neurons changed their spike rates almost linearly with the amplitude of this oscillatory potential. The oscillatory potential was termed the sound analog potential, because of its resemblance to the waveform of the stimulus tone. The amplitude of the sound analog potential recorded in NL varied systematically with the interaural time difference (ITD), which is one of the most important cues for sound localization. In order to investigate the mechanisms underlying ITD computation in the NM-NL circuit, we provide detailed theoretical descriptions of how phase-locked inputs form oscillating membrane potentials. We derive analytical expressions that relate presynaptic, synaptic, and postsynaptic factors to the signal and noise components of the oscillation in both the synaptic conductance and the membrane potential. Numerical simulations demonstrate the validity of the theoretical formulations for the entire frequency ranges tested (1–8 kHz) and potential effects of higher harmonics on NL neurons with low best frequencies (<2 kHz). PMID:24265616

Assessment of environmental enteropathy in the MAL-ED cohort study: theoretical and analytic framework.

PubMed

Kosek, Margaret; Guerrant, Richard L; Kang, Gagandeep; Bhutta, Zulfiqar; Yori, Pablo Peñataro; Gratz, Jean; Gottlieb, Michael; Lang, Dennis; Lee, Gwenyth; Haque, Rashidul; Mason, Carl J; Ahmed, Tahmeed; Lima, Aldo; Petri, William A; Houpt, Eric; Olortegui, Maribel Paredes; Seidman, Jessica C; Mduma, Estomih; Samie, Amidou; Babji, Sudhir

2014-11-01

Individuals in the developing world live in conditions of intense exposure to enteric pathogens due to suboptimal water and sanitation. These environmental conditions lead to alterations in intestinal structure, function, and local and systemic immune activation that are collectively referred to as environmental enteropathy (EE). This condition, although poorly defined, is likely to be exacerbated by undernutrition as well as being responsible for permanent growth deficits acquired in early childhood, vaccine failure, and loss of human potential. This article addresses the underlying theoretical and analytical frameworks informing the methodology proposed by the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development (MAL-ED) cohort study to define and quantify the burden of disease caused by EE within a multisite cohort. Additionally, we will discuss efforts to improve, standardize, and harmonize laboratory practices within the MAL-ED Network. These efforts will address current limitations in the understanding of EE and its burden on children in the developing world. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Cognitive theory in anorexia nervosa and bulimia nervosa: progress, development and future directions.

PubMed

Cooper, Myra J

2005-06-01

Important developments have taken place in cognitive theory of eating disorders (EDs) (and also in other disorders) since the review paper published by M.J. Cooper in 1997. The relevant empirical database has also expanded. Nevertheless, cognitive therapy for anorexia nervosa and bulimia nervosa, although helpful to many patients, leaves much to be desired. The current paper reviews the relevant empirical evidence collected, and the theoretical revisions that have been made to cognitive models of eating disorders, since 1997. The status and limitations of these developments are considered, including whether or not they meet the criteria for "good" theory. New theoretical developments relevant to cognitive explanations of eating disorders (second generation theories) are then presented, and the preliminary evidence that supports these is briefly reviewed. The lack of integration between cognitive theories of EDs and risk (vulnerability) factor research is noted, and a potential model that unites the two is noted. The implications of the review for future research and the development of cognitive theory in eating disorders are then discussed. These include the need for study of cognitive constructs not yet fully integrated (or indeed not yet applied clinically) into current theories and the need for cognitive theories of eating disorders to continue to evolve (as they have indeed done since 1997) in order to fully integrate such constructs. Treatment studies incorporating these new developments also urgently need to be undertaken.

Comparison of the Melting Temperatures of Classical and Quantum Water Potential Models

NASA Astrophysics Data System (ADS)

Du, Sen; Yoo, Soohaeng; Li, Jinjin

2017-08-01

As theoretical approaches and technical methods improve over time, the field of computer simulations for water has greatly progressed. Water potential models become much more complex when additional interactions and advanced theories are considered. Macroscopic properties of water predicted by computer simulations using water potential models are expected to be consistent with experimental outcomes. As such, discrepancies between computer simulations and experiments could be a criterion to comment on the performances of various water potential models. Notably, water can occur not only as liquid phases but also as solid and vapor phases. Therefore, the melting temperature related to the solid and liquid phase equilibrium is an effective parameter to judge the performances of different water potential models. As a mini review, our purpose is to introduce some water models developed in recent years and the melting temperatures obtained through simulations with such models. Moreover, some explanations referred to in the literature are described for the additional evaluation of the water potential models.

Effect of stigma reduction intervention strategies on HIV test uptake in low- and middle-income countries: a realist review protocol.

PubMed

Thapa, Subash; Hannes, Karin; Cargo, Margaret; Buve, Anne; Mathei, Catharina

2015-11-02

Several stigma reduction intervention strategies have been developed and tested for effectiveness in terms of increasing human immunodeficiency virus (HIV) test uptake. These strategies have been more effective in some contexts and less effective in others. Individual factors, such as lack of knowledge and fear of disclosure, and social-contextual factors, such as poverty and illiteracy, might influence the effect of stigma reduction intervention strategies on HIV test uptake in low- and middle-income countries. So far, it is not clearly known how the stigma reduction intervention strategies interact with these contextual factors to increase HIV test uptake. Therefore, we will conduct a review that will synthesize existing studies on stigma reduction intervention strategies to increase HIV test uptake to better understand the mechanisms underlying this process in low- and middle-income countries. A realist review will be conducted to unpack context-mechanism-outcome configurations of the effect of stigma reduction intervention strategies on HIV test uptake. Based on a scoping review, we developed a preliminary theoretical framework outlining a potential mechanism of how the intervention strategies influence HIV test uptake. Our realist synthesis will be used to refine the preliminary theoretical framework to better reflect mechanisms that are supported by existing evidence. Journal articles and grey literature will be searched following a purposeful sampling strategy. Data will be extracted and tested against the preliminary theoretical framework. Data synthesis and analysis will be performed in five steps: organizing extracted data into evidence tables, theming, formulating chains of inference from the identified themes, linking the chains of inference and developing generative mechanisms, and refining the framework. This will be the first realist review that offers both a quantitative and a qualitative exploration of the available evidence to develop and propose a theoretical framework that explains why and how HIV stigma reduction intervention strategies influence HIV test uptake in low- and middle-income countries. Our theoretical framework is meant to provide guidance to program managers on identifying the most effective stigma reduction intervention strategies to increase HIV test uptake. We also include advice on how to effectively implement these strategies to reduce the rate of HIV transmission. PROSPERO CRD42015023687.

A Theoretical Framework for Examining Geographical Variability in the Microphysical Mechanisms of Precipitation Development.

DTIC Science & Technology

1986-06-01

Energy and Natural Resources SWS Contract Report 391 FINAL REPORT A THEORETICAL FRAMEWORK FOR EXAMINING GEOGRAPHICAL VARIABILITY IN THE MICROPHYSICAL...U) A Theoretical Framework for Examining Geographical Variability in the Microphysical Mechanisms of Precipitation Development 12. PERSONAL AUTHOR(S...concentration. Oter key parameters include the degree of entrainment and stability of the environment. I 5 - T17 Unclassified ,.-. . A THEORETICAL FRAMEWORK FOR

Effect of foam on temperature prediction and heat recovery potential from biological wastewater treatment.

PubMed

Corbala-Robles, L; Volcke, E I P; Samijn, A; Ronsse, F; Pieters, J G

2016-05-15

Heat is an important resource in wastewater treatment plants (WWTPs) which can be recovered. A prerequisite to determine the theoretical heat recovery potential is an accurate heat balance model for temperature prediction. The insulating effect of foam present on the basin surface and its influence on temperature prediction were assessed in this study. Experiments were carried out to characterize the foam layer and its insulating properties. A refined dynamic temperature prediction model, taking into account the effect of foam, was set up. Simulation studies for a WWTP treating highly concentrated (manure) wastewater revealed that the foam layer had a significant effect on temperature prediction (3.8 ± 0.7 K over the year) and thus on the theoretical heat recovery potential (30% reduction when foam is not considered). Seasonal effects on the individual heat losses and heat gains were assessed. Additionally, the effects of the critical basin temperature above which heat is recovered, foam thickness, surface evaporation rate reduction and the non-absorbed solar radiation on the theoretical heat recovery potential were evaluated. Copyright © 2016 Elsevier Ltd. All rights reserved.

Is the Surface Potential Integral of a Dipole in a Volume Conductor Always Zero? A Cloud Over the Average Reference of EEG and ERP.

PubMed

Yao, Dezhong

2017-03-01

Currently, average reference is one of the most widely adopted references in EEG and ERP studies. The theoretical assumption is the surface potential integral of a volume conductor being zero, thus the average of scalp potential recordings might be an approximation of the theoretically desired zero reference. However, such a zero integral assumption has been proved only for a spherical surface. In this short communication, three counter-examples are given to show that the potential integral over the surface of a dipole in a volume conductor may not be zero. It depends on the shape of the conductor and the orientation of the dipole. This fact on one side means that average reference is not a theoretical 'gold standard' reference, and on the other side reminds us that the practical accuracy of average reference is not only determined by the well-known electrode array density and its coverage but also intrinsically by the head shape. It means that reference selection still is a fundamental problem to be fixed in various EEG and ERP studies.

Theoretical studies of potential energy surface and rotational spectra of Xe -H2O van der Waals complex

NASA Astrophysics Data System (ADS)

Wang, Lin; Yang, Minghui

2008-11-01

In this work we report an ab initio intermolecular potential energy surface and theoretical spectroscopic studies for Xe -H2O complex. The ab initio energies are calculated with CCSD(T) method and large basis sets (aug-cc-pVQZ for H and O and aug-cc-pVQZ-PP for Xe) augmented by a {3s3p2d2f1g} set of bond functions. This potential energy surface has a global minimum corresponding to a planar and nearly linear hydrogen bonded configuration with a well depth of 192.5cm-1 at intermolecular distance of 4.0Å, which is consistent with the previous determined potential by Wen and Jäger [J. Phys. Chem. A 110, 7560 (2006)]. The bound state calculations have been performed for the complex by approximating the water molecule as a rigid rotor. The theoretical rotational transition frequencies, isotopic shifts, nuclear quadrupole coupling constants, and structure parameters are in good agreement with the experimental observed values. The wavefunctions are analyzed to understand the dynamics of the ground and the first excited states.

Supersonic wings with significant leading-edge thrust at cruise

NASA Technical Reports Server (NTRS)

Robins, A. W.; Carlson, H. W.; Mack, R. J.

1980-01-01

Experimental/theoretical correlations are presented which show that significant levels of leading edge thrust are possible at supersonic speeds for certain planforms which match the theoretical thrust distribution potential with the supporting airfoil geometry. The analytical process employed spanwise distribution of both it and/or that component of full theoretical thrust which acts as vortex lift. Significantly improved aerodynamic performance in the moderate supersonic speed regime is indicated.

Professional Development and Use of Digital Technologies by Science Teachers: a Review of Theoretical Frameworks

NASA Astrophysics Data System (ADS)

Fernandes, Geraldo W. Rocha; Rodrigues, António M.; Ferreira, Carlos Alberto

2018-03-01

This article aims to characterise the research on science teachers' professional development programs that support the use of Information and Communication Technologies (ICTs) and the main trends concerning the theoretical frameworks (theoretical foundation, literature review or background) that underpin these studies. Through a systematic review of the literature, 76 articles were found and divided into two axes on training science teachers and the use of digital technologies with their categories. The first axis (characterisation of articles) presents the category key features that characterise the articles selected (major subjects, training and actions for the professional development and major ICT tools and digital resources). The second axis (trends of theoretical frameworks) has three categories organised in theoretical frameworks that emphasise the following: (a) the digital technologies, (b) prospects of curricular renewal and (c) cognitive processes. It also characterised a group of articles with theoretical frameworks that contain multiple elements without deepening them or that even lack a theoretical framework that supports the studies. In this review, we found that many professional development programs for teachers still use inadequate strategies for bringing about change in teacher practices. New professional development proposals are emerging with the objective of minimising such difficulties and this analysis could be a helpful tool to restructure those proposals.

Metabolic biotransformation half-lives in fish: QSAR modeling and consensus analysis.

PubMed

Papa, Ester; van der Wal, Leon; Arnot, Jon A; Gramatica, Paola

2014-02-01

Bioaccumulation in fish is a function of competing rates of chemical uptake and elimination. For hydrophobic organic chemicals bioconcentration, bioaccumulation and biomagnification potential are high and the biotransformation rate constant is a key parameter. Few measured biotransformation rate constant data are available compared to the number of chemicals that are being evaluated for bioaccumulation hazard and for exposure and risk assessment. Three new Quantitative Structure-Activity Relationships (QSARs) for predicting whole body biotransformation half-lives (HLN) in fish were developed and validated using theoretical molecular descriptors that seek to capture structural characteristics of the whole molecule and three data set splitting schemes. The new QSARs were developed using a minimal number of theoretical descriptors (n=9) and compared to existing QSARs developed using fragment contribution methods that include up to 59 descriptors. The predictive statistics of the models are similar thus further corroborating the predictive performance of the different QSARs; Q(2)ext ranges from 0.75 to 0.77, CCCext ranges from 0.86 to 0.87, RMSE in prediction ranges from 0.56 to 0.58. The new QSARs provide additional mechanistic insights into the biotransformation capacity of organic chemicals in fish by including whole molecule descriptors and they also include information on the domain of applicability for the chemical of interest. Advantages of consensus modeling for improving overall prediction and minimizing false negative errors in chemical screening assessments, for identifying potential sources of residual error in the empirical HLN database, and for identifying structural features that are not well represented in the HLN dataset to prioritize future testing needs are illustrated. © 2013.

A new pressure ulcer conceptual framework.

PubMed

Coleman, Susanne; Nixon, Jane; Keen, Justin; Wilson, Lyn; McGinnis, Elizabeth; Dealey, Carol; Stubbs, Nikki; Farrin, Amanda; Dowding, Dawn; Schols, Jos M G A; Cuddigan, Janet; Berlowitz, Dan; Jude, Edward; Vowden, Peter; Schoonhoven, Lisette; Bader, Dan L; Gefen, Amit; Oomens, Cees W J; Nelson, E Andrea

2014-10-01

This paper discusses the critical determinants of pressure ulcer development and proposes a new pressure ulcer conceptual framework. Recent work to develop and validate a new evidence-based pressure ulcer risk assessment framework was undertaken. This formed part of a Pressure UlceR Programme Of reSEarch (RP-PG-0407-10056), funded by the National Institute for Health Research. The foundation for the risk assessment component incorporated a systematic review and a consensus study that highlighted the need to propose a new conceptual framework. Discussion Paper. The new conceptual framework links evidence from biomechanical, physiological and epidemiological evidence, through use of data from a systematic review (search conducted March 2010), a consensus study (conducted December 2010-2011) and an international expert group meeting (conducted December 2011). A new pressure ulcer conceptual framework incorporating key physiological and biomechanical components and their impact on internal strains, stresses and damage thresholds is proposed. Direct and key indirect causal factors suggested in a theoretical causal pathway are mapped to the physiological and biomechanical components of the framework. The new proposed conceptual framework provides the basis for understanding the critical determinants of pressure ulcer development and has the potential to influence risk assessment guidance and practice. It could also be used to underpin future research to explore the role of individual risk factors conceptually and operationally. By integrating existing knowledge from epidemiological, physiological and biomechanical evidence, a theoretical causal pathway and new conceptual framework are proposed with potential implications for practice and research. © 2014 The Authors. Journal of Advanced Nursing Published by John Wiley & Sons Ltd.

A new pressure ulcer conceptual framework

PubMed Central

Coleman, Susanne; Nixon, Jane; Keen, Justin; Wilson, Lyn; McGinnis, Elizabeth; Dealey, Carol; Stubbs, Nikki; Farrin, Amanda; Dowding, Dawn; Schols, Jos MGA; Cuddigan, Janet; Berlowitz, Dan; Jude, Edward; Vowden, Peter; Schoonhoven, Lisette; Bader, Dan L; Gefen, Amit; Oomens, Cees WJ; Nelson, E Andrea

2014-01-01

Aim This paper discusses the critical determinants of pressure ulcer development and proposes a new pressure ulcer conceptual framework. Background Recent work to develop and validate a new evidence-based pressure ulcer risk assessment framework was undertaken. This formed part of a Pressure UlceR Programme Of reSEarch (RP-PG-0407-10056), funded by the National Institute for Health Research. The foundation for the risk assessment component incorporated a systematic review and a consensus study that highlighted the need to propose a new conceptual framework. Design Discussion Paper. Data Sources The new conceptual framework links evidence from biomechanical, physiological and epidemiological evidence, through use of data from a systematic review (search conducted March 2010), a consensus study (conducted December 2010–2011) and an international expert group meeting (conducted December 2011). Implications for Nursing A new pressure ulcer conceptual framework incorporating key physiological and biomechanical components and their impact on internal strains, stresses and damage thresholds is proposed. Direct and key indirect causal factors suggested in a theoretical causal pathway are mapped to the physiological and biomechanical components of the framework. The new proposed conceptual framework provides the basis for understanding the critical determinants of pressure ulcer development and has the potential to influence risk assessment guidance and practice. It could also be used to underpin future research to explore the role of individual risk factors conceptually and operationally. Conclusion By integrating existing knowledge from epidemiological, physiological and biomechanical evidence, a theoretical causal pathway and new conceptual framework are proposed with potential implications for practice and research. PMID:24684197

Individual behavioral phenotypes: an integrative meta-theoretical framework. Why "behavioral syndromes" are not analogs of "personality".

PubMed

Uher, Jana

2011-09-01

Animal researchers are increasingly interested in individual differences in behavior. Their interpretation as meaningful differences in behavioral strategies stable over time and across contexts, adaptive, heritable, and acted upon by natural selection has triggered new theoretical developments. However, the analytical approaches used to explore behavioral data still address population-level phenomena, and statistical methods suitable to analyze individual behavior are rarely applied. I discuss fundamental investigative principles and analytical approaches to explore whether, in what ways, and under which conditions individual behavioral differences are actually meaningful. I elaborate the meta-theoretical ideas underlying common theoretical concepts and integrate them into an overarching meta-theoretical and methodological framework. This unravels commonalities and differences, and shows that assumptions of analogy to concepts of human personality are not always warranted and that some theoretical developments may be based on methodological artifacts. Yet, my results also highlight possible directions for new theoretical developments in animal behavior research. Copyright © 2011 Wiley Periodicals, Inc.

The Role of Health Advocacy in Transitions from Pediatric to Adult Care for Children with Special Health Care Needs: Bridging Families, Provider and Community Services.

PubMed

Okumura, Megumi J; Saunders, Mara; Rehm, Roberta S

2015-01-01

Youth and young adults with special healthcare needs (YASHCN) experience challenges during transition from pediatric to adult care. Prior studies have not examined how community and healthcare resources can work together to assist YASHCN in transitioning from child-focused care and services to adult-oriented providers. The aim of this study was to develop a theoretical understanding of how family, healthcare providers and community supports can assist YASHCN during the transition from pediatric to adult healthcare and services. We conducted 41 semi-structured interviews with YASHCN aged 16-25, their family members and healthcare and community providers. We focused our interviews on support mechanisms, both within the traditional healthcare system, and those available in the community. Using grounded theory methods, we performed a multi-step analysis process. The theoretical code "Transition Advocacy" was developed from the data. This theoretical perspective arose from three major categories, which were developed in the analysis: "Fighting for healthcare", "Obtaining resources", and "Getting ready to transition". Transition Advocacy consists of the presence of, or need for, a healthcare "advocate" who did or can assist the YASHCN with the healthcare transition, particularly to navigate complex health or community services. The "advocate" role was performed by family members, healthcare or agency professionals, or sometimes the YASHCN themselves. If advocates were identified, youth were more likely to obtain needed services. Parents, health providers, and community agencies are potentially well-poised to assist transitioning YASHCN. Efforts to encourage development of strong advocacy skills will facilitate better transitions for YASHCN. Copyright © 2015 Elsevier Inc. All rights reserved.

The Role of Health Advocacy in Transitions from Pediatric to Adult Care for Children with Special Health Care Needs: Bridging Families, Provider and Community Services

PubMed Central

Okumura, Megumi; Saunders, Mara; Rehm, Roberta S.

2015-01-01

Background Youth and young adults with special healthcare needs (YASHCN) experience challenges during transition from pediatric to adult care. Prior studies have not examined how community and healthcare resources can work together to assist YASHCN in transitioning from child-focused care and services to adult-oriented providers. Objective To develop a theoretical understanding of how family, healthcare providers and community supports can assist YASHCN during the transition from pediatric to adult healthcare and services. Design/Methods We conducted 41 semi-structured interviews with YASHCN aged 16-25, their family members and healthcare and community providers. We focused our interviews on support mechanisms, both within the traditional healthcare system, and those available in the community. Using grounded theory methods, we performed a multi-step analysis process. Results The theoretical code “Transition Advocacy” was developed from the data. This theoretical perspective arose from three major categories, which were developed in the analysis: “Fighting for healthcare”, “Obtaining resources”, and “Getting ready to transition”. Transition Advocacy consists of the presence of, or need for, a healthcare ”advocate”’ who did or can assist the YASHCN with the healthcare transition, particularly to navigate complex health or community services. The ”advocate” role was performed by family members, healthcare or agency professionals, or sometimes the YASHCN themselves. If advocates were identified, youth were more likely to obtain needed services. Conclusions Parents, health providers, and community agencies are potentially well-poised to assist transitioning YASHCN. Efforts to encourage development of strong advocacy skills will facilitate better transitions for YASHCN. PMID:26228309

Investigating CSI: portrayals of DNA testing on a forensic crime show and their potential effects.

PubMed

Ley, Barbara L; Jankowski, Natalie; Brewer, Paul R

2012-01-01

The popularity of forensic crime shows such as CSI has fueled debate about their potential social impact. This study considers CSI's potential effects on public understandings regarding DNA testing in the context of judicial processes, the policy debates surrounding crime laboratory procedures, and the forensic science profession, as well as an effect not discussed in previous accounts: namely, the show's potential impact on public understandings of DNA and genetics more generally. To develop a theoretical foundation for research on the "CSI effect," it draws on cultivation theory, social cognitive theory, and audience reception studies. It then uses content analysis and textual analysis to illuminate how the show depicts DNA testing. The results demonstrate that CSI tends to depict DNA testing as routine, swift, useful, and reliable and that it echoes broader discourses about genetics. At times, however, the show suggests more complex ways of thinking about DNA testing and genetics.

Achieving swift equilibration of a Brownian particle using flow-fields

NASA Astrophysics Data System (ADS)

Patra, Ayoti; Jarzynski, Christopher

Can a system be driven to a targeted equilibrium state on a timescale that is much shorter than its natural equilibration time? In a recent experiment, the swift equilibration of an overdamped Brownian particle was achieved by use of an appropriately designed, time-dependent optical trap potential. Motivated by these results, we develop a general theoretical approach for guiding an ensemble of Brownian particles to track the instantaneous equilibrium distribution of a desired potential U (q , t) . In our approach, we use flow-fields associated with the parametric evolution of the targeted equilibrium state to construct an auxiliary potential U (q , t) , such that dynamics under the composite potential U (t) + U (t) achieves the desired evolution. Our results establish a close connection between the swift equilibration of Brownian particles, quantum shortcuts to adiabaticity, and the dissipationless driving of a classical, Hamiltonian system.

Testing aspects of Carl Rogers's theory of creative environments: child-rearing antecedents of creative potential in young adolescents.

PubMed

Harrington, D M; Block, J H; Block, J

1987-04-01

Longitudinal data involving 106 children and their parents were used to test preschool child-rearing implications of Carl Rogers's theory of creativity-fostering environments (Rogers, 1954). Indices were developed for each parent and for each mother-father combination that reflected the degree to which the parents' child-rearing practices and interactions with their preschool children matched the recommendations implicit in Rogers's description of a creativity-fostering environment. The three indices of Rogers-prescribed child-rearing practices each correlated positively (rs = .38 to .46) and significantly (all ps less than .001) with a composite index of creative potential in early adolescence, 7 to 11 years later. Rogers-prescribed preschool child-rearing practices also emerged as significant antecedents of adolescent creative potential in regression/path analyses that held constant the influence of sex, preschool intelligence, and preschool creative potential. Theoretical and methodological aspects of the study are discussed.

The Development of a Design and Construction Process Protocol to Support the Home Modification Process Delivered by Occupational Therapists

PubMed Central

Ormerod, Marcus; Newton, Rita

2018-01-01

Modifying the home environments of older people as they age in place is a well-established health and social care intervention. Using design and construction methods to redress any imbalance caused by the ageing process or disability within the home environment, occupational therapists are seen as the experts in this field of practice. However, the process used by occupational therapists when modifying home environments has been criticised for being disorganised and not founded on theoretical principles and concepts underpinning the profession. To address this issue, research was conducted to develop a design and construction process protocol specifically for home modifications. A three-stage approach was taken for the analysis of qualitative data generated from an online survey, completed by 135 occupational therapists in the UK. Using both the existing occupational therapy intervention process model and the design and construction process protocol as the theoretical frameworks, a 4-phase, 9-subphase design and construction process protocol for home modifications was developed. Overall, the study is innovative in developing the first process protocol for home modifications, potentially providing occupational therapists with a systematic and effective approach to the design and delivery of home modification services for older and disabled people. PMID:29682348

The Development of a Design and Construction Process Protocol to Support the Home Modification Process Delivered by Occupational Therapists.

PubMed

Russell, Rachel; Ormerod, Marcus; Newton, Rita

2018-01-01

Modifying the home environments of older people as they age in place is a well-established health and social care intervention. Using design and construction methods to redress any imbalance caused by the ageing process or disability within the home environment, occupational therapists are seen as the experts in this field of practice. However, the process used by occupational therapists when modifying home environments has been criticised for being disorganised and not founded on theoretical principles and concepts underpinning the profession. To address this issue, research was conducted to develop a design and construction process protocol specifically for home modifications. A three-stage approach was taken for the analysis of qualitative data generated from an online survey, completed by 135 occupational therapists in the UK. Using both the existing occupational therapy intervention process model and the design and construction process protocol as the theoretical frameworks, a 4-phase, 9-subphase design and construction process protocol for home modifications was developed. Overall, the study is innovative in developing the first process protocol for home modifications, potentially providing occupational therapists with a systematic and effective approach to the design and delivery of home modification services for older and disabled people.

Recent advances on the development and regulation of flower color in ornamental plants

PubMed Central

Zhao, Daqiu; Tao, Jun

2015-01-01

Flower color is one of the most important features of ornamental plants. Its development and regulation are influenced by many internal and external factors. Therefore, understanding the mechanism of color development and its regulation provides an important theoretical basis and premise for the cultivation and improvement of new color varieties of ornamental plants. This paper outlines the functions of petal tissue structure, as well as the distribution and type of pigments, especially anthocyanins, in color development. The progress of research on flower color regulation with a focus on physical factors, chemical factors, and genetic engineering is introduced. The shortcomings of flower color research and the potential directions for future development are explored to provide a broad background for flower color improvements in ornamental plants. PMID:25964787

Theoretical studies of solar-pumped lasers

NASA Astrophysics Data System (ADS)

Harries, Wynford L.

1988-06-01

The investigation of stimulated emission causing transitions from the B(1) pi sub u state of sodium to the overlapping 2(1) sigma(+) sub g electronic state has been continued. A new method of estimating the Franck-Condon factors has been developed which instead of fitting the molecular potential curves with Morse functions, estimates the V(r) dependence by interpolation from given potential curves. The results for the sum of the rates from one vibrational level in the upper state to all the levels in the lower state show good agreement with the previous method, implying that curve crossing by stimulated emission due to photons from the oven is an important mechanism in sodium.

Sputtering of Lunar Regolith by Solar Wind Protons and Heavy Ions, and General Aspects of Potential Sputtering

NASA Technical Reports Server (NTRS)

Alnussirat, S. T.; Sabra, M. S.; Barghouty, A. F.; Rickman, Douglas L.; Meyer, F.

2014-01-01

New simulation results for the sputtering of lunar soil surface by solar-wind protons and heavy ions will be presented. Previous simulation results showed that the sputtering process has significant effects and plays an important role in changing the surface chemical composition, setting the erosion rate and the sputtering process timescale. In this new work and in light of recent data, we briefly present some theoretical models which have been developed to describe the sputtering process and compare their results with recent calculation to investigate and differentiate the roles and the contributions of potential (or electrodynamic) sputtering from the standard (or kinetic) sputtering.

Theoretical Studies of Nanoclusters (Briefing Charts)

DTIC Science & Technology

2015-07-23

nanoclusters. However, scanning transmission electron microscopy ( STEM ) measures show cluster inversion occurred to produce MgyCux(!) a) copper atoms b...methane (née CLL -1) as a potential explosive ingredient: a theoretical study”, Propellants, Explosives, Pyrotechnics 38, 9-13 (2013). Jesus Paulo L

Fundamental Challenges for Modeling Electrochemical Energy Storage Systems at the Atomic Scale.

PubMed

Groß, Axel

2018-04-23

There is a strong need to improve the efficiency of electrochemical energy storage, but progress is hampered by significant technological and scientific challenges. This review describes the potential contribution of atomic-scale modeling to the development of more efficient batteries, with a particular focus on first-principles electronic structure calculations. Numerical and theoretical obstacles are discussed, along with ways to overcome them, and some recent examples are presented illustrating the insights into electrochemical energy storage that can be gained from quantum chemical studies.

A theoretical/experimental program to develop active optical pollution sensors, part 2

NASA Technical Reports Server (NTRS)

Poultney, S. K.

1975-01-01

Progress is reported on experimental investigations of Lidar and the application of Lidar to environmental and atmospheric science. Specifically the following programs are considered: calibration and application of the LaRC 48-inch Lidar; efficient and certain detection of SO2 and other gases in the calibration tank using the Raman Stack Monitor Lidar; the potential of Lidar remote sensing from the space shuttle; and the planning and mounting of efforts to realize the promise of backscatter differential absorption Lidar.

Coded spread spectrum digital transmission system design study

NASA Technical Reports Server (NTRS)

Heller, J. A.; Odenwalder, J. P.; Viterbi, A. J.

1974-01-01

Results are presented of a comprehensive study of the performance of Viterbi-decoded convolutional codes in the presence of nonideal carrier tracking and bit synchronization. A constraint length 7, rate 1/3 convolutional code and parameters suitable for the space shuttle coded communications links are used. Mathematical models are developed and theoretical and simulation results are obtained to determine the tracking and acquisition performance of the system. Pseudorandom sequence spread spectrum techniques are also considered to minimize potential degradation caused by multipath.

Nonlinear aerodynamic wing design

NASA Technical Reports Server (NTRS)

Bonner, Ellwood

1985-01-01

The applicability of new nonlinear theoretical techniques is demonstrated for supersonic wing design. The new technology was utilized to define outboard panels for an existing advanced tactical fighter model. Mach 1.6 maneuver point design and multi-operating point compromise surfaces were developed and tested. High aerodynamic efficiency was achieved at the design conditions. A corollary result was that only modest supersonic penalties were incurred to meet multiple aerodynamic requirements. The nonlinear potential analysis of a practical configuration arrangement correlated well with experimental data.

Photoacoustic Doppler effect from flowing small light-absorbing particles.

PubMed

Fang, Hui; Maslov, Konstantin; Wang, Lihong V

2007-11-02

From the flow of a suspension of micrometer-scale carbon particles, the photoacoustic Doppler shift is observed. As predicted theoretically, the observed Doppler shift equals half of that in Doppler ultrasound and does not depend on the direction of laser illumination. This new physical phenomenon provides a basis for developing photoacoustic Doppler flowmetry, which can potentially be used for detecting fluid flow in optically scattering media and especially low-speed blood flow of relatively deep microcirculation in biological tissue.

Lobster eye as a collector for water window microscopy

NASA Astrophysics Data System (ADS)

Pina, L.; Maršíková, V.; Inneman, A.; Nawaz, M. F.; Jančárek, A.; Havlíková, R.

2017-08-01

Imaging in EUV, SXR and XR spectral bands of radiation is of increasing interest. Material science, biology and hot plasma are examples of relevant fast developing areas. Applications include spectroscopy, astrophysics, Soft X-ray Ray metrology, Water Window microscopy, radiography and tomography. Especially Water Window imaging has still not fully recognized potential in biology and medicine microscopy applications. Theoretical study and design of Lobster Eye (LE) optics as a collector for water window (WW) microscopy and comparison with a similar size ellipsoidal mirror condensor are presented.

Electrocatalysis of borohydride oxidation: a review of density functional theory approach combined with experimental validation.

PubMed

Escaño, Mary Clare Sison; Arevalo, Ryan Lacdao; Gyenge, Elod; Kasai, Hideaki

2014-09-03

The electrocatalysis of borohydride oxidation is a complex, up-to-eight-electron transfer process, which is essential for development of efficient direct borohydride fuel cells. Here we review the progress achieved by density functional theory (DFT) calculations in explaining the adsorption of BH4(-) on various catalyst surfaces, with implications for electrocatalyst screening and selection. Wherever possible, we correlate the theoretical predictions with experimental findings, in order to validate the proposed models and to identify potential directions for further advancements.

Electrocatalysis of borohydride oxidation: a review of density functional theory approach combined with experimental validation

NASA Astrophysics Data System (ADS)

Sison Escaño, Mary Clare; Lacdao Arevalo, Ryan; Gyenge, Elod; Kasai, Hideaki

2014-09-01

The electrocatalysis of borohydride oxidation is a complex, up-to-eight-electron transfer process, which is essential for development of efficient direct borohydride fuel cells. Here we review the progress achieved by density functional theory (DFT) calculations in explaining the adsorption of BH4- on various catalyst surfaces, with implications for electrocatalyst screening and selection. Wherever possible, we correlate the theoretical predictions with experimental findings, in order to validate the proposed models and to identify potential directions for further advancements.

Theoretical Borderlands: Using Multiple Theoretical Perspectives to Challenge Inequitable Power Structures in Student Development Theory

ERIC Educational Resources Information Center

Abes, Elisa S.

2009-01-01

This article is an exploration of possibilities and methodological considerations for using multiple theoretical perspectives in research that challenges inequitable power structures in student development theory. Specifically, I explore methodological considerations when partnering queer theory and constructivism in research on lesbian identity…

From Weber to Parsons and Shutz: The Eclipse of History in Modern Social Theory.

ERIC Educational Resources Information Center

Zaret, David

1980-01-01

Compares the relationship between theoretical synthesis and historical research in light of research by Max Weber, Talcott Parsons, and Alfred Schutz. Traces theoretical developments within one subfield of sociology (action theory) and relates these developments to research problems confronting contemporary theoretical work in sociology. (DB)

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

Sudiarta, I. Wayan; Angraini, Lily Maysari, E-mail: lilyangraini@unram.ac.id

We have applied the finite difference time domain (FDTD) method with the supersymmetric quantum mechanics (SUSY-QM) procedure to determine excited energies of one dimensional quantum systems. The theoretical basis of FDTD, SUSY-QM, a numerical algorithm and an illustrative example for a particle in a one dimensional square-well potential were given in this paper. It was shown that the numerical results were in excellent agreement with theoretical results. Numerical errors produced by the SUSY-QM procedure was due to errors in estimations of superpotentials and supersymmetric partner potentials.

Unifying theoretical framework for deciphering the oxygen reduction reaction on platinum.

PubMed

Huang, Jun; Zhang, Jianbo; Eikerling, Michael

2018-05-07

Rapid conversion of oxygen into water is crucial to the operation of polymer electrolyte fuel cells and other emerging electrochemical energy technologies. Chemisorbed oxygen species play double-edged roles in this reaction, acting as vital intermediates on one hand and site-blockers on the other. Any attempt to decipher the oxygen reduction reaction (ORR) must first relate the formation of oxygen intermediates to basic electronic and electrostatic properties of the catalytic surface, and then link it to parameters of catalyst activity. An approach that accomplishes this feat will be of great utility for catalyst materials development and predictive model formulation of electrode operation. Here, we present a theoretical framework for the multiple interrelated surface phenomena and processes involved, particularly, by incorporating the double-layer effects. It sheds light on the roles of oxygen intermediates and gives out the Tafel slope and exchange current density as continuous functions of electrode potential. Moreover, it develops the concept of a rate determining term, which should replace the concept of a rate determining step for multielectron reactions, and offers a new perspective on the volcano relation of the ORR.

Hypermentalizing, attachment, and epistemic trust in adolescent BPD: Clinical illustrations.

PubMed

Bo, Sune; Sharp, Carla; Fonagy, Peter; Kongerslev, Mickey

2017-04-01

Borderline personality disorder (BPD) has been shown to be a valid and reliable diagnosis in adolescents and associated with a decrease in both general and social functioning. With evidence linking BPD in adolescents to poor prognosis, it is important to develop a better understanding of factors and mechanisms contributing to the development of BPD. This could potentially enhance our knowledge and facilitate the design of novel treatment programs and interventions for this group. In this paper, we outline a theoretical model of BPD in adolescents linking the original mentalization-based theory of BPD, with recent extensions of the theory that focuses on hypermentalizing and epistemic trust. We then provide clinical case vignettes to illustrate this extended theoretical model of BPD. Furthermore, we suggest a treatment approach to BPD in adolescents that focuses on the reduction of hypermentalizing and epistemic mistrust. We conclude with an integration of theory and practice in the final section of the paper and make recommendations for future work in this area. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Predicting vapor-liquid phase equilibria with augmented ab initio interatomic potentials

NASA Astrophysics Data System (ADS)

Vlasiuk, Maryna; Sadus, Richard J.

2017-06-01

The ability of ab initio interatomic potentials to accurately predict vapor-liquid phase equilibria is investigated. Monte Carlo simulations are reported for the vapor-liquid equilibria of argon and krypton using recently developed accurate ab initio interatomic potentials. Seventeen interatomic potentials are studied, formulated from different combinations of two-body plus three-body terms. The simulation results are compared to either experimental or reference data for conditions ranging from the triple point to the critical point. It is demonstrated that the use of ab initio potentials enables systematic improvements to the accuracy of predictions via the addition of theoretically based terms. The contribution of three-body interactions is accounted for using the Axilrod-Teller-Muto plus other multipole contributions and the effective Marcelli-Wang-Sadus potentials. The results indicate that the predictive ability of recent interatomic potentials, obtained from quantum chemical calculations, is comparable to that of accurate empirical models. It is demonstrated that the Marcelli-Wang-Sadus potential can be used in combination with accurate two-body ab initio models for the computationally inexpensive and accurate estimation of vapor-liquid phase equilibria.

Potential theory of radiation

NASA Technical Reports Server (NTRS)

Chiu, Huei-Huang

1989-01-01

A theoretical method is being developed by which the structure of a radiation field can be predicted by a radiation potential theory, similar to a classical potential theory. The introduction of a scalar potential is justified on the grounds that the spectral intensity vector is irrotational. The vector is also solenoidal in the limits of a radiation field in complete radiative equilibrium or in a vacuum. This method provides an exact, elliptic type equation that will upgrade the accuracy and the efficiency of the current CFD programs required for the prediction of radiation and flow fields. A number of interesting results emerge from the present study. First, a steady state radiation field exhibits an optically modulated inverse square law distribution character. Secondly, the unsteady radiation field is structured with two conjugate scalar potentials. Each is governed by a Klein-Gordon equation with a frictional force and a restoring force. This steady potential field structure and the propagation of radiation potentials are consistent with the well known results of classical electromagnetic theory. The extension of the radiation potential theory for spray combustion and hypersonic flow is also recommended.

Predicting vapor-liquid phase equilibria with augmented ab initio interatomic potentials.

PubMed

Vlasiuk, Maryna; Sadus, Richard J

2017-06-28

The ability of ab initio interatomic potentials to accurately predict vapor-liquid phase equilibria is investigated. Monte Carlo simulations are reported for the vapor-liquid equilibria of argon and krypton using recently developed accurate ab initio interatomic potentials. Seventeen interatomic potentials are studied, formulated from different combinations of two-body plus three-body terms. The simulation results are compared to either experimental or reference data for conditions ranging from the triple point to the critical point. It is demonstrated that the use of ab initio potentials enables systematic improvements to the accuracy of predictions via the addition of theoretically based terms. The contribution of three-body interactions is accounted for using the Axilrod-Teller-Muto plus other multipole contributions and the effective Marcelli-Wang-Sadus potentials. The results indicate that the predictive ability of recent interatomic potentials, obtained from quantum chemical calculations, is comparable to that of accurate empirical models. It is demonstrated that the Marcelli-Wang-Sadus potential can be used in combination with accurate two-body ab initio models for the computationally inexpensive and accurate estimation of vapor-liquid phase equilibria.

A theoretical explanation for the Central Molecular Zone asymmetry

NASA Astrophysics Data System (ADS)

Sormani, Mattia C.; Treß, Robin G.; Ridley, Matthew; Glover, Simon C. O.; Klessen, Ralf S.; Binney, James; Magorrian, John; Smith, Rowan

2018-04-01

It has been known for more than 30 yr that the distribution of molecular gas in the innermost 300 parsecs of the Milky Way, the Central Molecular Zone, is strongly asymmetric. Indeed, approximately three quarters of molecular emission come from positive longitudes, and only one quarter from negative longitudes. However, despite much theoretical effort, the origin of this asymmetry has remained a mystery. Here, we show that the asymmetry can be neatly explained by unsteady flow of gas in a barred potential. We use high-resolution 3D hydrodynamical simulations coupled to a state-of-the-art chemical network. Despite the initial conditions and the bar potential being point symmetric with respect to the Galactic Centre, asymmetries develop spontaneously due to the combination of a hydrodynamical instability known as the `wiggle instability' and the thermal instability. The observed asymmetry must be transient: observations made tens of megayears in the past or in the future would often show an asymmetry in the opposite sense. Fluctuations of amplitude comparable to the observed asymmetry occur for a large fraction of time in our simulations, and suggest that the present is not an exceptional moment in the life of our Galaxy.

Assessing Gas-Hydrate Prospects on the North Slope of Alaska - Theoretical Considerations

USGS Publications Warehouse

Lee, Myung W.; Collett, Timothy S.; Agena, Warren F.

2008-01-01

Gas-hydrate resource assessment on the Alaska North Slope using 3-D and 2-D seismic data involved six important steps: (1) determining the top and base of the gas-hydrate stability zone, (2) 'tying' well log information to seismic data through synthetic seismograms, (3) differentiating ice from gas hydrate in the permafrost interval, (4) developing an acoustic model for the reservoir and seal, (5) developing a method to estimate gas-hydrate saturation and thickness from seismic attributes, and (6) assessing the potential gas-hydrate prospects from seismic data based on potential migration pathways, source, reservoir quality, and other relevant geological information. This report describes the first five steps in detail using well logs and provides theoretical backgrounds for resource assessments carried out by the U.S. Geological Survey. Measured and predicted P-wave velocities enabled us to tie synthetic seismograms to the seismic data. The calculated gas-hydrate stability zone from subsurface wellbore temperature data enabled us to focus our effort on the most promising depth intervals in the seismic data. A typical reservoir in this area is characterized by the P-wave velocity of 1.88 km/s, porosity of 42 percent, and clay volume content of 5 percent, whereas seal sediments encasing the reservoir are characterized by the P-wave velocity of 2.2 km/s, porosity of 32 percent, and clay volume content of 20 percent. Because the impedance of a reservoir without gas hydrate is less than that of the seal, a complex amplitude variation with respect to gas-hydrate saturation is predicted, namely polarity change, amplitude blanking, and high seismic amplitude (a bright spot). This amplitude variation with gas-hydrate saturation is the physical basis for the method used to quantify the resource potential of gas hydrates in this assessment.

Full-dimensional analytical potential energy surface describing the gas-phase Cl + C2H6 reaction and kinetics study of rate constants and kinetic isotope effects.

PubMed

Rangel, Cipriano; Espinosa-Garcia, Joaquin

2018-02-07

Within the Born-Oppenheimer approximation a full-dimensional analytical potential energy surface, PES-2017, was developed for the gas-phase hydrogen abstraction reaction between the chlorine atom and ethane, which is a nine body system. This surface presents a valence-bond/molecular mechanics functional form dependent on 60 parameters and is fitted to high-level ab initio calculations. This reaction presents little exothermicity, -2.30 kcal mol -1 , with a low height barrier, 2.44 kcal mol -1 , and intermediate complexes in the entrance and exit channels. We found that the energetic description was strongly dependent on the ab initio level used and it presented a very flat topology in the entrance channel, which represents a theoretical challenge in the fitting process. In general, PES-2017 reproduces the ab initio information used as input, which is merely a test of self-consistency. As a first test of the quality of the PES-2017, a theoretical kinetics study was performed in the temperature range 200-1400 K using two approaches, i.e. the variational transition-state theory and quasi-classical trajectory calculations, with spin-orbit effects. The rate constants show reasonable agreement with experiments in the whole temperature range, with the largest differences at the lowest temperatures, and this behaviour agrees with previous theoretical studies, thus indicating the inherent difficulties in the theoretical simulation of the kinetics of the title reaction. Different sources of error were analysed, such as the limitations of the PES and theoretical methods, recrossing effects, and the tunnelling effect, which is negligible in this reaction, and the manner in which the spin-orbit effects were included in this non-relativistic study. We found that the variation of spin-orbit coupling along the reaction path, and the influence of the reactivity of the excited Cl( 2 P 1/2 ) state, have relative importance, but do not explain the whole discrepancy. Finally, the activation energy and the kinetics isotope effects reproduce the experimental information.

Transitions theory: a trajectory of theoretical development in nursing.

PubMed

Im, Eun-Ok

2011-01-01

There have been very few investigations into how any single nursing theory has actually evolved historically. In this paper, a trajectory of theoretical development in nursing is explored through reviewing the theoretical development of a single nursing theory-transitions theory. The literature related to transitions theory was searched and retrieved using multiple databases. Ninety-nine papers were analyzed according to type of theory, populations of interest, sources of theorizing, and theoretical methods. Transitions theory originated in research but was initially borrowed. It also arose in research with immigrants and from national and international collaborative research efforts. A product of mentoring, transitions theory is used widely in nursing education, research, and practice. Diverse thoughts related to transitions theory coexist. For future theoretical development in nursing, we need to remain open to new ideas and continue to engage in multiple collaborative efforts. Copyright © 2011 Elsevier Inc. All rights reserved.

The development of silicon carbide-based power electronics devices

NASA Astrophysics Data System (ADS)

Hopkins, Richard H.; Perkins, John F.

1995-01-01

In 1989 Westinghouse created an internally funded initiative to develop silicon carbide materials and device technology for a variety of potential commercial and military applications. Westinghouse saw silicon carbide as having the potential for dual use. For space applications, size and weight reductions could be achieved, together with increased reliability. Terrestrially, uses in harsh-temperature environments would be enabled. Theoretically, the physical and electrical properties of silicon carbide were highly promising for high-power, high-temperature, radiation-hardened electronics. However, bulk material with the requisite electronic qualities was not available, and the methods needed to produce a silicon carbide wafer—to fabricate high-quality devices—and to transition these technologies into a commercial product were considered to be a high-risk investment. It was recognized that through a collaborative effort, the CCDS could provide scientific expertise in several areas, thus reducing this risk. These included modeling of structures, electrical contacts, dielectrics, and epitaxial growth. This collaboration has been very successful, with developed technologies being transferred to Westinghouse.

10 years of mindlines: a systematic review and commentary.

PubMed

Wieringa, Sietse; Greenhalgh, Trisha

2015-04-09

In 2004, Gabbay and le May showed that clinicians generally base their decisions on mindlines-internalised and collectively reinforced tacit guidelines-rather than consulting written clinical guidelines. We considered how the concept of mindlines has been taken forward since. We searched databases from 2004 to 2014 for the term 'mindline(s)' and tracked all sources citing Gabbay and le May's 2004 article. We read and re-read papers to gain familiarity and developed an interpretive analysis and taxonomy by drawing on the principles of meta-narrative systematic review. In our synthesis of 340 papers, distinguished between authors who used mindlines purely in name ('nominal' view) sometimes dismissing them as a harmful phenomenon, and authors who appeared to have understood the term's philosophical foundations. The latter took an 'in-practice' view (studying how mindlines emerge and spread in real-world settings), a 'theoretical and philosophical' view (extending theory) or a 'solution focused' view (exploring how to promote and support mindline development). We found that it is not just clinicians who develop mindlines: so do patients, in face-to-face and (potentially) online communities. Theoretical publications on mindlines have continued to challenge the rationalist assumptions of evidence-based medicine (EBM). Conventional EBM assumes a single, knowable reality and seeks to strip away context to generate universal predictive rules. In contrast, mindlines are predicated on a more fluid, embodied and intersubjective view of knowledge; they accommodate context and acknowledge multiple realities. When considering how knowledge spreads, the concept of mindlines requires us to go beyond the constraining notions of 'dissemination' and 'translation' to study tacit knowledge and the interactive human processes by which such knowledge is created, enacted and shared. Solution-focused publications described mindline-promoting initiatives such as relationship-building, collaborative learning and thought leadership. The concept of mindlines challenges the naïve rationalist view of knowledge implicit in some EBM publications, but the term appears to have been misunderstood (and prematurely dismissed) by some authors. By further studying mindlines empirically and theoretically, there is potential to expand EBM's conceptual toolkit to produce richer forms of 'evidence-based' knowledge. We outline a suggested research agenda for achieving this goal.

Laser-tissue interaction studies using a modified alexandrite laser

NASA Astrophysics Data System (ADS)

Paterson, Lorna Menzies

This thesis forms a detailed study of the alexandrite laser and its potential in the medical field. Applications suggested include dermatological and dental procedures. This body of work encompasses these areas and touches on wider potential applications. A theoretical model has been developed to explain and predict the reaction of tissue to laser light with the wavelength and temporal profile of the alexandrite laser. The interaction of the fundamental 755 nm radiation with a variety of human tissues was initially studied and further studies carried out on porcine liver with long pulse and Q-switched laser pulses. The results were then compared to an analytical theoretical model and also to the standard de Beer's model of an exponential dependence of the light intensity on the attenuation coefficient of the tissue. The presence of a plume of debris was also taken into account. The interaction of the alexandrite laser output with hard dental material was studied. It was observed that 755 and 378 nm (second harmonic) laser light does not significantly affect healthy enamel or dentine. The selective ablation of carious material at 378 nm was observed. A system to photograph a plume of debris leaving an interaction site, with a known time delay from the moment of irradiation, was developed using a frequency doubled, Q-switched Nd:YAG laser. This system could be used to measure plume velocities and also to observe the different stages of fast interactions, e.g. the different thresholds for water evaporation and tissue removal in infrared irradiation of water rich tissue. The removal of tattoo pigment by the alexandrite laser light was investigated using excised human tattoo sections. The limited number of samples available showed a clearing of the intradermal pigment and professionally tattooed pig skin was then used as a replacement for excised human tattoo samples. Professional tattoo pigment embedded in agar was used to look at the acoustic waves induced by laser irradiation at 755 nm with a pulselength of 180 ns. The acoustic waves produced were detected using a PVDF membrane hydrophone (GEC Marconi) and compared to theoretical results. Pressures of up to 1.4 MPa were produced with irradiances of up to 10.6 MWcm-2 which were comparable to the irradiances used to clear the pigment embedded in human skin. The pressure gradient at these pressures is approximately 1.09x1010 Pam-1 giving a pressure difference of 1.09+/-0.17 MPa over a 100 ?m particle. This is not enough to damage human skin which has a tensile strength of 7.3 MPa. A theoretical model was developed, using the accepted theory of pressure waves in a fluid medium, to predict the amplitude of the pressure waves produced in the samples. The experimental results compared well with the ideal theoretical case. The distribution of the laser energy throughout the samples was modelled with the velocity of the debris plume ejected from the sample surface predicted. This velocity was measured and found to be comparable to the velocity previously calculated theoretically.

Designing and operating infrastructure for nonstationary flood risk management

NASA Astrophysics Data System (ADS)

Doss-Gollin, J.; Farnham, D. J.; Lall, U.

2017-12-01

Climate exhibits organized low-frequency and regime-like variability at multiple time scales, causing the risk associated with climate extremes such as floods and droughts to vary in time. Despite broad recognition of this nonstationarity, there has been little theoretical development of ideas for the design and operation of infrastructure considering the regime structure of such changes and their potential predictability. We use paleo streamflow reconstructions to illustrate an approach to the design and operation of infrastructure to address nonstationary flood and drought risk. Specifically, we consider the tradeoff between flood control and conservation storage, and develop design and operation principles for allocating these storage volumes considering both a m-year project planning period and a n-year historical sampling record. As n increases, the potential uncertainty in probabilistic estimates of the return periods associated with the T-year extreme event decreases. As the duration m of the future operation period decreases, the uncertainty associated with the occurrence of the T-year event also increases. Finally, given the quasi-periodic nature of the system it may be possible to offer probabilistic predictions of the conditions in the m-year future period, especially if m is small. In the context of such predictions, one can consider that a m-year prediction may have lower bias, but higher variance, than would be associated with using a stationary estimate from the preceding n years. This bias-variance trade-off, and the potential for considering risk management for multiple values of m, provides an interesting system design challenge. We use wavelet-based simulation models in a Bayesian framework to estimate these biases and uncertainty distributions and devise a risk-optimized decision rule for the allocation of flood and conservation storage. The associated theoretical development also provides a methodology for the sizing of storage for new infrastructure under nonstationarity, and an examination of risk adaptation measures which consider both short term and long term options simultaneously.

Development of the infrared instrument for gas detection

NASA Astrophysics Data System (ADS)

Chen, Ching-Wei; Chen, Chia-Ray

2017-08-01

MWIR (Mid-Wave Infrared) spectroscopy shows a large potential in the current IR devices market, due to its multiple applications, such as gas detection, chemical analysis, industrial monitoring, combustion and flame characterization. It opens this technique to the fields of application, such as industrial monitoring and control, agriculture and environmental monitoring. However, a major barrier, which is the lack of affordable specific key elements such a MWIR light sources and low cost uncooled detectors, have held it back from its widespread use. In this paper an uncooled MWIR detector combined with image enhancement technique is reported. This investigation shows good results in gas leakage detection test. It also verify the functions of self-developed MWIR lens and optics. A good agreement in theoretical design and experiment give us the lessons learned for the potential application in infrared satellite technology. A brief discussions will also be presented in this paper.

Identity configurations: a new perspective on identity formation in contemporary society.

PubMed

Schachter, Elli P

2004-02-01

This paper deals with the theoretical construct of "identity configuration." It portrays the different possible ways in which individuals configure the relationship among potentially conflicting identifications in the process of identity formation. In order to explicate these configurations, I analyzed narratives of identity development retold by individuals describing personal identity conflicts that arise within a larger context of sociocultural conflict. Thirty Jewish modern orthodox young adults were interviewed regarding a potentially conflictual identity issue (i.e. their religious and sexual development). Their deliberations, as described in the interviews, were examined, and four different configurations were identified: a configuration based on choice and suppression; an assimilative and synthesizing configuration; a confederacy of identifications; and a configuration based on the thrill of dissonance. The different configurations are illustrated through exemplars, and the possible implications of the concept of "configuration" for identity theory are discussed.

The information geometry of chaos

NASA Astrophysics Data System (ADS)

Cafaro, Carlo

2008-10-01

In this Thesis, we propose a new theoretical information-geometric framework (IGAC, Information Geometrodynamical Approach to Chaos) suitable to characterize chaotic dynamical behavior of arbitrary complex systems. First, the problem being investigated is defined; its motivation and relevance are discussed. The basic tools of information physics and the relevant mathematical tools employed in this work are introduced. The basic aspects of Entropic Dynamics (ED) are reviewed. ED is an information-constrained dynamics developed by Ariel Caticha to investigate the possibility that laws of physics---either classical or quantum---may emerge as macroscopic manifestations of underlying microscopic statistical structures. ED is of primary importance in our IGAC. The notion of chaos in classical and quantum physics is introduced. Special focus is devoted to the conventional Riemannian geometrodynamical approach to chaos (Jacobi geometrodynamics) and to the Zurek-Paz quantum chaos criterion of linear entropy growth. After presenting this background material, we show that the ED formalism is not purely an abstract mathematical framework, but is indeed a general theoretical scheme from which conventional Newtonian dynamics is obtained as a special limiting case. The major elements of our IGAC and the novel notion of information geometrodynamical entropy (IGE) are introduced by studying two "toy models". To illustrate the potential power of our IGAC, one application is presented. An information-geometric analogue of the Zurek-Paz quantum chaos criterion of linear entropy growth is suggested. Finally, concluding remarks emphasizing strengths and weak points of our approach are presented and possible further research directions are addressed. At this stage of its development, IGAC remains an ambitious unifying information-geometric theoretical construct for the study of chaotic dynamics with several unsolved problems. However, based on our recent findings, we believe it already provides an interesting, innovative and potentially powerful way to study and understand the very important and challenging problems of classical and quantum chaos.

Elevated carbon dioxide is predicted to promote coexistence among competing species in a trait-based model

DOE PAGES

Ali, Ashehad A.; Medlyn, Belinda E.; Aubier, Thomas G.; ...

2015-10-06

Differential species responses to atmospheric CO 2 concentration (C a) could lead to quantitative changes in competition among species and community composition, with flow-on effects for ecosystem function. However, there has been little theoretical analysis of how elevated C a (eC a) will affect plant competition, or how composition of plant communities might change. Such theoretical analysis is needed for developing testable hypotheses to frame experimental research. Here, we investigated theoretically how plant competition might change under eC a by implementing two alternative competition theories, resource use theory and resource capture theory, in a plant carbon and nitrogen cycling model.more » The model makes several novel predictions for the impact of eC a on plant community composition. Using resource use theory, the model predicts that eC a is unlikely to change species dominance in competition, but is likely to increase coexistence among species. Using resource capture theory, the model predicts that eC a may increase community evenness. Collectively, both theories suggest that eC a will favor coexistence and hence that species diversity should increase with eC a. Our theoretical analysis leads to a novel hypothesis for the impact of eC a on plant community composition. In this study, the hypothesis has potential to help guide the design and interpretation of eC a experiments.« less

A theoretical study of colloidal forces near an amphiphilic polymer brush

NASA Astrophysics Data System (ADS)

Wu, Jianzhong

2011-03-01

Polymer-based ``non-stick'' coatings are promising as the next generation of effective, environmentally-friendly marine antifouling systems that minimize nonspecific adsorption of extracellular polymeric substances (EPS). However, design and development of such systems are impeded by the poor knowledge of polymer-mediated interactions of biomacromolecules with the protected substrate. In this work, a polymer density functional theory (DFT) is used to predict the potential of mean force between spherical biomacromolecules and amphiphilic copolymer brushes within a coarse-grained model that captures essential nonspecific interactions such as the molecular excluded volume effects and the hydrophobic energies. The relevance of theoretical results for practical control of the EPS adsorption is discussed in terms of the efficiency of different brush configurations to prevent biofouling. It is shown that the most effective antifouling surface may be accomplished by using amphiphilic brushes with a long hydrophilic backbone and a hydrophobic end at moderate grafting density.

A multi target approach to control chemical reactions in their inhomogeneous solvent environment

NASA Astrophysics Data System (ADS)

Keefer, Daniel; Thallmair, Sebastian; Zauleck, Julius P. P.; de Vivie-Riedle, Regina

2015-12-01

Shaped laser pulses offer a powerful tool to manipulate molecular quantum systems. Their application to chemical reactions in solution is a promising concept to redesign chemical synthesis. Along this road, theoretical developments to include the solvent surrounding are necessary. An appropriate theoretical treatment is helpful to understand the underlying mechanisms. In our approach we simulate the solvent by randomly selected snapshots from molecular dynamics trajectories. We use multi target optimal control theory to optimize pulses for the various arrangements of explicit solvent molecules simultaneously. This constitutes a major challenge for the control algorithm, as the solvent configurations introduce a large inhomogeneity to the potential surfaces. We investigate how the algorithm handles the new challenges and how well the controllability of the system is preserved with increasing complexity. Additionally, we introduce a way to statistically estimate the efficiency of the optimized laser pulses in the complete thermodynamical ensemble.

Stereotype Threat and College Academic Performance: A Latent Variables Approach*

PubMed Central

Owens, Jayanti; Massey, Douglas S.

2013-01-01

Stereotype threat theory has gained experimental and survey-based support in helping explain the academic underperformance of minority students at selective colleges and universities. Stereotype threat theory states that minority students underperform because of pressures created by negative stereotypes about their racial group. Past survey-based studies, however, are characterized by methodological inefficiencies and potential biases: key theoretical constructs have only been measured using summed indicators and predicted relationships modeled using ordinary least squares. Using the National Longitudinal Survey of Freshman, this study overcomes previous methodological shortcomings by developing a latent construct model of stereotype threat. Theoretical constructs and equations are estimated simultaneously from multiple indicators, yielding a more reliable, valid, and parsimonious test of key propositions. Findings additionally support the view that social stigma can indeed have strong negative effects on the academic performance of pejoratively stereotyped racial-minority group members, not only in laboratory settings, but also in the real world. PMID:23950616

Towards a mathematical theory of meaningful communication

NASA Astrophysics Data System (ADS)

Corominas-Murtra, Bernat; Fortuny, Jordi; Solé, Ricard V.

2014-04-01

Meaning has been left outside most theoretical approaches to information in biology. Functional responses based on an appropriate interpretation of signals have been replaced by a probabilistic description of correlations between emitted and received symbols. This assumption leads to potential paradoxes, such as the presence of a maximum information associated to a channel that creates completely wrong interpretations of the signals. Game-theoretic models of language evolution and other studies considering embodied communicating agents show that the correct (meaningful) match resulting from agent-agent exchanges is always achieved and natural systems obviously solve the problem correctly. Inspired by the concept of duality of the communicative sign stated by the swiss linguist Ferdinand de Saussure, here we present a complete description of the minimal system necessary to measure the amount of information that is consistently decoded. Several consequences of our developments are investigated, such as the uselessness of a certain amount of information properly transmitted for communication among autonomous agents.

Traumatogenic Processes and Pathways to Mental Health Outcomes for Sexual Minorities Exposed to Bias Crime Information.

PubMed

Lannert, Brittany K

2015-07-01

Vicarious traumatization of nonvictim members of communities targeted by bias crimes has been suggested by previous qualitative studies and often dominates public discussion following bias events, but proximal and distal responses of community members have yet to be comprehensively modeled, and quantitative research on vicarious responses is scarce. This comprehensive review integrates theoretical and empirical literatures in social, clinical, and physiological psychology in the development of a model of affective, cognitive, and physiological responses of lesbian, gay, and bisexual individuals upon exposure to information about bias crimes. Extant qualitative research in vicarious response to bias crimes is reviewed in light of theoretical implications and methodological limitations. Potential pathways to mental health outcomes are outlined, including accumulative effects of anticipatory defensive responding, multiplicative effects of minority stress, and putative traumatogenic physiological and cognitive processes of threat. Methodological considerations, future research directions, and clinical implications are also discussed. © The Author(s) 2014.

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.

Neuropsychology and neuropharmacology of P3a and P3b.

PubMed

Polich, John; Criado, José R

2006-05-01

Perspectives on the P300 event-related brain potential (ERP) are reviewed by outlining the distinction between the P3a and P3b subcomponents. The critical factor for eliciting P3a is how target/standard discrimination difficulty rather than novelty modulates task processing. The neural loci of P3a and P3b generation are sketched and a theoretical model is developed. P3a originates from stimulus-driven disruption of frontal attention engagement during task processing. P3b originates when temporal-parietal mechanisms process the stimulus information for memory storage. The neuropharmacological implications of this view are then outlined by evaluating how acute and chronic use of ethanol, marijuana, and nicotine affect P3a and P3b. The findings suggest that the circuit underlying ERP generation is influenced in a different ways for acute intake and varies between chronic use levels across drugs. Theoretical implications are assessed.

Arterial Spin Labeling (ASL) fMRI: advantages, theoretical constrains, and experimental challenges in neurosciences.

PubMed

Borogovac, Ajna; Asllani, Iris

2012-01-01

Cerebral blood flow (CBF) is a well-established correlate of brain function and therefore an essential parameter for studying the brain at both normal and diseased states. Arterial spin labeling (ASL) is a noninvasive fMRI technique that uses arterial water as an endogenous tracer to measure CBF. ASL provides reliable absolute quantification of CBF with higher spatial and temporal resolution than other techniques. And yet, the routine application of ASL has been somewhat limited. In this review, we start by highlighting theoretical complexities and technical challenges of ASL fMRI for basic and clinical research. While underscoring the main advantages of ASL versus other techniques such as BOLD, we also expound on inherent challenges and confounds in ASL perfusion imaging. In closing, we expound on several exciting developments in the field that we believe will make ASL reach its full potential in neuroscience research.

Study preferences for exemplar variability in self-regulated category learning.

PubMed

Wahlheim, Christopher N; DeSoto, K Andrew

2017-02-01

Increasing exemplar variability during category learning can enhance classification of novel exemplars from studied categories. Four experiments examined whether participants preferred variability when making study choices with the goal of later classifying novel exemplars. In Experiments 1-3, participants were familiarised with exemplars of birds from multiple categories prior to making category-level assessments of learning and subsequent choices about whether to receive more variability or repetitions of exemplars during study. After study, participants classified novel exemplars from studied categories. The majority of participants showed a consistent preference for variability in their study, but choices were not related to category-level assessments of learning. Experiment 4 provided evidence that study preferences were based primarily on theoretical beliefs in that most participants indicated a preference for variability on questionnaires that did not include prior experience with exemplars. Potential directions for theoretical development and applications to education are discussed.

Towards Developing a Theoretical Framework for Measuring Public Sector Managers' Career Success

ERIC Educational Resources Information Center

Rasdi, Roziah Mohd; Ismail, Maimunah; Uli, Jegak; Noah, Sidek Mohd

2009-01-01

Purpose: The purpose of this paper is to develop a theoretical framework for measuring public sector managers' career success. Design/methodology/approach: The theoretical foundation used in this study is social cognitive career theory. To conduct a literature search, several keywords were identified, i.e. career success, objective and subjective…

Allostatic load: A theoretical model for understanding the relationship between maternal posttraumatic stress disorder and adverse birth outcomes.

PubMed

Li, Yang; Rosemberg, Marie-Anne Sanon; Seng, Julia S

2018-07-01

Adverse birth outcomes such as preterm birth and low birth weight are significant public health concerns and contribute to neonatal morbidity and mortality. Studies have increasingly been exploring the predictive effects of maternal posttraumatic stress disorder (PTSD) on adverse birth outcomes. However, the biological mechanisms by which maternal PTSD affects birth outcomes are not well understood. Allostatic load refers to the cumulative dysregulations of the multiple physiological systems as a response to multiple social-ecological levels of chronic stress. Allostatic load has been well documented in relation to both chronic stress and adverse health outcomes in non-pregnant populations. However, the mediating role of allostatic load is less understood when it comes to maternal PTSD and adverse birth outcomes. To propose a theoretical model that depicts how allostatic load could mediate the impact of maternal PTSD on birth outcomes. We followed the procedures for theory synthesis approach described by Walker and Avant (2011), including specifying focal concepts, identifying related factors and relationships, and constructing an integrated representation. We first present a theoretical overview of the allostatic load theory and the other 4 relevant theoretical models. Then we provide a brief narrative review of literature that empirically supports the propositions of the integrated model. Finally, we describe our theoretical model. The theoretical model synthesized has the potential to advance perinatal research by delineating multiple biomarkers to be used in future. After it is well validated, it could be utilized as the theoretical basis for health care professionals to identify high-risk women by evaluating their experiences of psychosocial and traumatic stress and to develop and evaluate service delivery and clinical interventions that might modify maternal perceptions or experiences of stress and eliminate their impacts on adverse birth outcomes. Copyright © 2018. Published by Elsevier Ltd.

Sustainable IT and IT for Sustainability

NASA Astrophysics Data System (ADS)

Liu, Zhenhua

Energy and sustainability have become one of the most critical issues of our generation. While the abundant potential of renewable energy such as solar and wind provides a real opportunity for sustainability, their intermittency and uncertainty present a daunting operating challenge. This thesis aims to develop analytical models, deployable algorithms, and real systems to enable efficient integration of renewable energy into complex distributed systems with limited information. The first thrust of the thesis is to make IT systems more sustainable by facilitating the integration of renewable energy into these systems. IT represents the fastest growing sectors in energy usage and greenhouse gas pollution. Over the last decade there are dramatic improvements in the energy efficiency of IT systems, but the efficiency improvements do not necessarily lead to reduction in energy consumption because more servers are demanded. Further, little effort has been put in making IT more sustainable, and most of the improvements are from improved "engineering" rather than improved "algorithms". In contrast, my work focuses on developing algorithms with rigorous theoretical analysis that improve the sustainability of IT. In particular, this thesis seeks to exploit the flexibilities of cloud workloads both (i) in time by scheduling delay-tolerant workloads and (ii) in space by routing requests to geographically diverse data centers. These opportunities allow data centers to adaptively respond to renewable availability, varying cooling efficiency, and fluctuating energy prices, while still meeting performance requirements. The design of the enabling algorithms is however very challenging because of limited information, non-smooth objective functions and the need for distributed control. Novel distributed algorithms are developed with theoretically provable guarantees to enable the "follow the renewables" routing. Moving from theory to practice, I helped HP design and implement industry's first Net-zero Energy Data Center. The second thrust of this thesis is to use IT systems to improve the sustainability and efficiency of our energy infrastructure through data center demand response. The main challenges as we integrate more renewable sources to the existing power grid come from the fluctuation and unpredictability of renewable generation. Although energy storage and reserves can potentially solve the issues, they are very costly. One promising alternative is to make the cloud data centers demand responsive. The potential of such an approach is huge. To realize this potential, we need adaptive and distributed control of cloud data centers and new electricity market designs for distributed electricity resources. My work is progressing in both directions. In particular, I have designed online algorithms with theoretically guaranteed performance for data center operators to deal with uncertainties under popular demand response programs. Based on local control rules of customers, I have further designed new pricing schemes for demand response to align the interests of customers, utility companies, and the society to improve social welfare.

New Ways of Treating Data for Diatomic Molecule 'shelf' and Double-Minimum States

NASA Astrophysics Data System (ADS)

Le Roy, Robert J.; Tao, Jason; Khanna, Shirin; Pashov, Asen; Tellinghuisen, Joel

2017-06-01

Electronic states whose potential energy functions have 'shelf' or double-minimum shapes have always presented special challenges because, as functions of vibrational quantum number, the vibrational energies/spacings and inertial rotational constants either have an abrupt change of character with discontinuous slope, or past a given point, become completely chaotic. The present work shows that a `traditional' methodology developed for deep `regular' single-well potentials can also provide accurate `parameter-fit' descriptions of the v-dependence of the vibrational energies and rotational constants of shelf-state potentials that allow a conventional RKR calculation of their Potential energy functions. It is also shown that a merging of Pashov's uniquely flexible 'spline point-wise' potential function representation with Le Roy's `Morse/Long-Range' (MLR) analytic functional form which automatically incorporates the correct theoretically known long-range form, yields an analytic function that incorporates most of the advantages of both approaches. An illustrative application of this method to data to a double-minimum state of Na_2 will be described.

A quantum perturbative pair distribution for determining interatomic potentials from extended x-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Piazza, F.

2002-11-01

In this paper we develop a technique for determining interatomic potentials in materials in the quantum regime from single-shell extended x-ray absorption spectroscopy (EXAFS) spectra. We introduce a pair distribution function, based on ordinary quantum time-independent perturbation theory. In the proposed scheme, the model potential parameters enter the distribution through a fourth-order Taylor expansion of the potential, and are directly refined in the fit of the model signal to the experimental spectrum. We discuss in general the validity of our theoretical framework, namely the quantum regime and perturbative treatment, and work out a simple tool for monitoring the sensitivity of our theory in determining lattice anharmonicities based on the statistical F-test. As an example, we apply our formalism to an EXAFS spectrum at the Ag K edge of AgI at T = 77 K. We determine the Ag-I potential parameters and find good agreement with previous studies.

Nuclear half-lives for {alpha}-radioactivity of elements with 100 {<=} Z {<=} 130

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

Chowdhury, P. Roy; Samanta, C.; Physics Department, Gottwald Science Center, University of Richmond, Richmond, VA 23173

2008-11-15

Theoretical estimates for the half-lives of about 1700 isotopes of heavy elements with 100 {<=} Z {<=} 130 are tabulated using theoretical Q-values. The quantum mechanical tunneling probabilities are calculated within a WKB framework using microscopic nuclear potentials. The microscopic nucleus-nucleus potentials are obtained by folding the densities of interacting nuclei with a density-dependent M3Y effective nucleon-nucleon interaction. The {alpha}-decay half-lives calculated in this formalism using the experimental Q-values were found to be in good agreement over a wide range of experimental data spanning about 20 orders of magnitude. The theoretical Q-values used for the present calculations are extracted frommore » three different mass estimates viz. Myers-Swiatecki, Muntian-Hofmann-Patyk-Sobiczewski, and Koura-Tachibana-Uno-Yamada.« less

Adjectives That Aren't: An ERP-Theoretical Analysis of Adjectives in Spanish

ERIC Educational Resources Information Center

Bartlett, Laura B.

2013-01-01

This thesis investigates the syntactic status of adjectives in Spanish through a crossdisciplinary perspective, incorporating methodologies from both theoretical linguistics and neurolinguistics, specifically, event-related potentials (ERPs). It presents conflicting theories about the syntax of adjectives and explores the ways that the processing…

Theoretical and Experimental Estimations of Volumetric Inductive Phase Shift in Breast Cancer Tissue

NASA Astrophysics Data System (ADS)

González, C. A.; Lozano, L. M.; Uscanga, M. C.; Silva, J. G.; Polo, S. M.

2013-04-01

Impedance measurements based on magnetic induction for breast cancer detection has been proposed in some studies. This study evaluates theoretical and experimentally the use of a non-invasive technique based on magnetic induction for detection of patho-physiological conditions in breast cancer tissue associated to its volumetric electrical conductivity changes through inductive phase shift measurements. An induction coils-breast 3D pixel model was designed and tested. The model involves two circular coils coaxially centered and a human breast volume centrally placed with respect to the coils. A time-harmonic numerical simulation study addressed the effects of frequency-dependent electrical properties of tumoral tissue on the volumetric inductive phase shift of the breast model measured with the circular coils as inductor and sensor elements. Experimentally; five female volunteer patients with infiltrating ductal carcinoma previously diagnosed by the radiology and oncology departments of the Specialty Clinic for Women of the Mexican Army were measured by an experimental inductive spectrometer and the use of an ergonomic inductor-sensor coil designed to estimate the volumetric inductive phase shift in human breast tissue. Theoretical and experimental inductive phase shift estimations were developed at four frequencies: 0.01, 0.1, 1 and 10 MHz. The theoretical estimations were qualitatively in agreement with the experimental findings. Important increments in volumetric inductive phase shift measurements were evident at 0.01MHz in theoretical and experimental observations. The results suggest that the tested technique has the potential to detect pathological conditions in breast tissue associated to cancer by non-invasive monitoring. Further complementary studies are warranted to confirm the observations.

Flexible bent rod model with a saturating induced dipole moment to study the electric linear dichroism of DNA fragments

NASA Astrophysics Data System (ADS)

Bertolotto, Jorge A.; Umazano, Juan P.

2016-06-01

In the present work we make a theoretical study of the steady state electric linear dichroism of DNA fragments in aqueous solution. The here developed theoretical approach considers a flexible bent rod model with a saturating induced dipole moment. The electric polarizability tensor of bent DNA fragments is calculated considering a phenomenological model which theoretical and experimental backgroung is presented here. The model has into account the electric polarizability longitudinal and transversal to the macroion. Molecular flexibility is described using an elastic potential. We consider DNA fragments originally bent with bending fluctuations around an average bending angle. The induced dipole moment is supposed constant once the electric field strength grows up at critical value. To calculate the reduced electric linear dichroism we determine the optical factor considering the basis of the bent DNA perpendicular to the molecular axis. The orientational distribution function has into account the anisotropic electric properties and the molecule flexibility. We applied the present theoretical background to fit electric dichroism experimental data of DNA fragments reported in the bibliography in a wide range of molecular weight and electric field. From these fits, values of DNA physical properties are estimated. We compare and discuss the results here obtained with the theoretical and experimental data presented by other authors. The original contributions of this work are: the inclusion of the transversal electric polarizability saturating with the electric field, the description of the electric properties with an electric polarizability tensor dependant on the bending angle and the use of an arc model originally bent.

Steady, Oscillatory, and Unsteady Subsonic and Supersonic Aerodynamics, production version (SOUSSA-P 1.1). Volume 1: Theoretical manual. [Green function

NASA Technical Reports Server (NTRS)

Morino, L.

1980-01-01

Recent developments of the Green's function method and the computer program SOUSSA (Steady, Oscillatory, and Unsteady Subsonic and Supersonic Aerodynamics) are reviewed and summarized. Applying the Green's function method to the fully unsteady (transient) potential equation yields an integro-differential-delay equation. With spatial discretization by the finite-element method, this equation is approximated by a set of differential-delay equations in time. Time solution by Laplace transform yields a matrix relating the velocity potential to the normal wash. Premultiplying and postmultiplying by the matrices relating generalized forces to the potential and the normal wash to the generalized coordinates one obtains the matrix of the generalized aerodynamic forces. The frequency and mode-shape dependence of this matrix makes the program SOUSSA useful for multiple frequency and repeated mode-shape evaluations.

Hazard Detection Analysis for a Forward-Looking Interferometer

NASA Technical Reports Server (NTRS)

West, Leanne; Gimmestad, Gary; Herkert, Ralph; Smith, William L.; Kireev, Stanislav; Schaffner, Philip R.; Daniels, Taumi S.; Cornman, Larry B.; Sharman, Robert; Weekley, Andrew;

On the Hilbert-Huang Transform Theoretical Foundation

NASA Technical Reports Server (NTRS)

Kizhner, Semion; Blank, Karin; Huang, Norden E.

2004-01-01

The Hilbert-Huang Transform [HHT] is a novel empirical method for spectrum analysis of non-linear and non-stationary signals. The HHT is a recent development and much remains to be done to establish the theoretical foundation of the HHT algorithms. This paper develops the theoretical foundation for the convergence of the HHT sifting algorithm and it proves that the finest spectrum scale will always be the first generated by the HHT Empirical Mode Decomposition (EMD) algorithm. The theoretical foundation for cutting an extrema data points set into two parts is also developed. This then allows parallel signal processing for the HHT computationally complex sifting algorithm and its optimization in hardware.

Magnetism in curved geometries

NASA Astrophysics Data System (ADS)

Streubel, Robert; Fischer, Peter; Kronast, Florian; Kravchuk, Volodymyr P.; Sheka, Denis D.; Gaididei, Yuri; Schmidt, Oliver G.; Makarov, Denys

2016-09-01

Extending planar two-dimensional structures into the three-dimensional space has become a general trend in multiple disciplines, including electronics, photonics, plasmonics and magnetics. This approach provides means to modify conventional or to launch novel functionalities by tailoring the geometry of an object, e.g. its local curvature. In a generic electronic system, curvature results in the appearance of scalar and vector geometric potentials inducing anisotropic and chiral effects. In the specific case of magnetism, even in the simplest case of a curved anisotropic Heisenberg magnet, the curvilinear geometry manifests two exchange-driven interactions, namely effective anisotropy and antisymmetric exchange, i.e. Dzyaloshinskii-Moriya-like interaction. As a consequence, a family of novel curvature-driven effects emerges, which includes magnetochiral effects and topologically induced magnetization patterning, resulting in theoretically predicted unlimited domain wall velocities, chirality symmetry breaking and Cherenkov-like effects for magnons. The broad range of altered physical properties makes these curved architectures appealing in view of fundamental research on e.g. skyrmionic systems, magnonic crystals or exotic spin configurations. In addition to these rich physics, the application potential of three-dimensionally shaped objects is currently being explored as magnetic field sensorics for magnetofluidic applications, spin-wave filters, advanced magneto-encephalography devices for diagnosis of epilepsy or for energy-efficient racetrack memory devices. These recent developments ranging from theoretical predictions over fabrication of three-dimensionally curved magnetic thin films, hollow cylinders or wires, to their characterization using integral means as well as the development of advanced tomography approaches are in the focus of this review.

Animal models of ocular angiogenesis: from development to pathologies.

PubMed

Liu, Chi-Hsiu; Wang, Zhongxiao; Sun, Ye; Chen, Jing

2017-11-01

Pathological angiogenesis in the eye is an important feature in the pathophysiology of many vision-threatening diseases, including retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration, as well as corneal diseases with abnormal angiogenesis. Development of reproducible and reliable animal models of ocular angiogenesis has advanced our understanding of both the normal development and the pathobiology of ocular neovascularization. These models have also proven to be valuable experimental tools with which to easily evaluate potential antiangiogenic therapies beyond eye research. This review summarizes the current available animal models of ocular angiogenesis. Models of retinal and choroidal angiogenesis, including oxygen-induced retinopathy, laser-induced choroidal neovascularization, and transgenic mouse models with deficient or spontaneous retinal/choroidal neovascularization, as well as models with induced corneal angiogenesis, are widely used to investigate the molecular and cellular basis of angiogenic mechanisms. Theoretical concepts and experimental protocols of these models are outlined, as well as their advantages and potential limitations, which may help researchers choose the most suitable models for their investigative work.-Liu, C.-H., Wang, Z., Sun, Y., Chen, J. Animal models of ocular angiogenesis: from development to pathologies. © FASEB.

Working Memory Underpins Cognitive Development, Learning, and Education

PubMed Central

Cowan, Nelson

2014-01-01

Working memory is the retention of a small amount of information in a readily accessible form. It facilitates planning, comprehension, reasoning, and problem-solving. I examine the historical roots and conceptual development of the concept and the theoretical and practical implications of current debates about working memory mechanisms. Then I explore the nature of cognitive developmental improvements in working memory, the role of working memory in learning, and some potential implications of working memory and its development for the education of children and adults. The use of working memory is quite ubiquitous in human thought, but the best way to improve education using what we know about working memory is still controversial. I hope to provide some directions for research and educational practice. PMID:25346585

Contracting out of health services in developing countries.

PubMed

McPake, B; Banda, E E

1994-03-01

Contracting out is emerging as a common policy issue in a number of developing countries. The theoretical case for contracting out suggests many advantages in combining public finance with private provision. However, practical difficulties such as those of ensuring that competition takes place between potential contractors, that competition leads to efficiency and that contracts and the process of contracting are effectively managed, suggest that such advantages may not always be realized. Most countries are likely only to contemplate restricted contracting of small-scale non-clinical services in the short term. Prerequisites of more extensive models appear to be the development of information systems and human resources to that end. Some urban areas of larger countries may have the existing preconditions for more successful large-scale contracting.

A proposal for evaluating cognition in assertiveness.

PubMed

Vagos, Paula; Pereira, Anabela

2010-09-01

This article presents the development process and initial psychometric features of an instrument for evaluating cognition in assertiveness. This is an essential social skill for adolescent development and seems to encompass emotional, behavioral, and cognitive aspects. The instrument was created by combining both empirical and theoretical methods for item construction, aiming to evaluate the cognitive realm of assertiveness. A sample of 996 adolescent students was used to test for reliability and validity. Results indicate good psychometric properties. The instrument is composed of 4 subscales: Outer Emotional Support, Functional Personal Ability, Interpersonal Management, and Affective Personal Ability. The Assertive Interpersonal Schema Questionnaire may potentially be a useful tool in the diagnosis of, understanding of, and development of a treatment plan for individuals with persistent difficulties in social events.

Dependence and caring in clinical communication: The relevance of attachment and other theories

PubMed Central

Salmon, Peter; Young, Bridget

2009-01-01

Objective Clinical relationships are usually asymmetric, being defined by patients’ dependence and practitioners’ care. Our aims are to: (i) identify literature that can contribute to theory for researching and teaching clinical communication from this perspective; (ii) highlight where theoretical development is needed; and (iii) test the utility of the emerging theory by identifying whether it leads to implications for educational practice. Methods Selective and critical review of research concerned with dependence and caring in clinical and non-clinical relationships. Results Attachment theory helps to understand patients’ need to seek safety in relationships with expert and authoritative practitioners but is of limited help in understanding practitioners’ caring. Different theories that formulate practitioners’ care as altruistic, rewarded by personal connection or as a contract indicate the potential importance of practitioners’ emotions, values and sense of role in understanding their clinical communication. Conclusion Extending the theoretical grounding of clinical communication can accommodate patients’ dependence and practitioners’ caring without return to medical paternalism. Practice implications A broader theoretical base will help educators to address the inherent subjectivity of clinical relationships, and researchers to distinguish scientific questions about how patients and clinicians are from normative questions about how they should be. PMID:19157761

Dependence and caring in clinical communication: the relevance of attachment and other theories.

PubMed

Salmon, Peter; Young, Bridget

2009-03-01

Clinical relationships are usually asymmetric, being defined by patients' dependence and practitioners' care. Our aims are to: (i) identify literature that can contribute to theory for researching and teaching clinical communication from this perspective; (ii) highlight where theoretical development is needed; and (iii) test the utility of the emerging theory by identifying whether it leads to implications for educational practice. Selective and critical review of research concerned with dependence and caring in clinical and non-clinical relationships. Attachment theory helps to understand patients' need to seek safety in relationships with expert and authoritative practitioners but is of limited help in understanding practitioners' caring. Different theories that formulate practitioners' care as altruistic, rewarded by personal connection or as a contract indicate the potential importance of practitioners' emotions, values and sense of role in understanding their clinical communication. Extending the theoretical grounding of clinical communication can accommodate patients' dependence and practitioners' caring without return to medical paternalism. A broader theoretical base will help educators to address the inherent subjectivity of clinical relationships, and researchers to distinguish scientific questions about how patients and clinicians are from normative questions about how they should be.

Recent theoretical, neural, and clinical advances in sustained attention research

PubMed Central

Fortenbaugh, Francesca C.; DeGutis, Joseph; Esterman, Michael

2017-01-01

Models of attention often distinguish between attention subtypes, with classic models separating orienting, switching, and sustaining functions. Compared to other forms of attention, the neurophysiological basis of sustaining attention has received far less attention yet it is known that momentary failures of sustained attention can have far ranging negative impacts in healthy individuals and lasting sustained attention deficits are pervasive in clinical populations. In recent years, however, there has been increased interest in characterizing moment-to-moment fluctuations in sustained attention in addition to the overall vigilance decrement and understanding how these neurocognitive systems change over the lifespan and across various clinical populations. The use of novel neuroimaging paradigms and statistical approaches has allowed for better characterization of the neural networks supporting sustained attention, and highlighted dynamic interactions within and across multiple distributed networks that predict behavioral performance. These advances have also provided potential biomarkers to identify individuals with sustained attention deficits. These findings have led to new theoretical models of why sustaining focused attention is a challenge for individuals and form the basis for the next generation of sustained attention research, which seeks to accurately diagnose and develop theoretically-driven treatments for sustained attention deficits that affect a variety of clinical populations. PMID:28260249

Mapping physician Twitter networks: describing how they work as a first step in understanding connectivity, information flow, and message diffusion.

PubMed

Mishori, Ranit; Singh, Lisa Oberoi; Levy, Brendan; Newport, Calvin

2014-04-14

Twitter is becoming an important tool in medicine, but there is little information on Twitter metrics. In order to recommend best practices for information dissemination and diffusion, it is important to first study and analyze the networks. This study describes the characteristics of four medical networks, analyzes their theoretical dissemination potential, their actual dissemination, and the propagation and distribution of tweets. Open Twitter data was used to characterize four networks: the American Medical Association (AMA), the American Academy of Family Physicians (AAFP), the American Academy of Pediatrics (AAP), and the American College of Physicians (ACP). Data were collected between July 2012 and September 2012. Visualization was used to understand the follower overlap between the groups. Actual flow of the tweets for each group was assessed. Tweets were examined using Topsy, a Twitter data aggregator. The theoretical information dissemination potential for the groups is large. A collective community is emerging, where large percentages of individuals are following more than one of the groups. The overlap across groups is small, indicating a limited amount of community cohesion and cross-fertilization. The AMA followers' network is not as active as the other networks. The AMA posted the largest number of tweets while the AAP posted the fewest. The number of retweets for each organization was low indicating dissemination that is far below its potential. To increase the dissemination potential, medical groups should develop a more cohesive community of shared followers. Tweet content must be engaging to provide a hook for retweeting and reaching potential audience. Next steps call for content analysis, assessment of the behavior and actions of the messengers and the recipients, and a larger-scale study that considers other medical groups using Twitter.

Multistage Complexity in Language Proficiency Assessment: A Framework for Aligning Theoretical Perspectives, Test Development, and Psychometrics

ERIC Educational Resources Information Center

Luecht, Richard M.

2003-01-01

This article contends that the necessary links between constructs and test scores/decisions in language assessment must be established through principled design procedures that align three models: (1) a theoretical construct model; (2) a test development model; and (3) a psychometric scoring model. The theoretical construct model articulates the…

Development Mechanism of an Integrated Model for Training of a Specialist and Conceptual-Theoretical Activity of a Teacher

ERIC Educational Resources Information Center

Marasulov, Akhmat; Saipov, Amangeldi; ?rymbayeva, Kulimkhan; Zhiyentayeva, Begaim; Demeuov, Akhan; Konakbaeva, Ulzhamal; Bekbolatova, Akbota

2016-01-01

The aim of the study is to examine the methodological-theoretical construction bases for development mechanism of an integrated model for a specialist's training and teacher's conceptual-theoretical activity. Using the methods of generalization of teaching experience, pedagogical modeling and forecasting, the authors determine the urgent problems…

Digital Education: Opportunities for Social Collaboration. Digital Education and Learning

ERIC Educational Resources Information Center

Thomas, Michael, Ed.

2011-01-01

This timely collection of theoretical and applied studies examines the pedagogical potential and realities of digital technologies in a wide range of disciplinary contexts across the educational spectrum. By mixing content-based chapters with a theoretical perspective with case studies detailing actual teaching approaches utilizing digital…

Recording membrane potential changes through photoacoustic voltage sensitive dye

NASA Astrophysics Data System (ADS)

Zhang, Haichong K.; Kang, Jeeun; Yan, Ping; Abou, Diane S.; Le, Hanh N. D.; Thorek, Daniel L. J.; Kang, Jin U.; Gjedde, Albert; Rahmim, Arman; Wong, Dean F.; Loew, Leslie M.; Boctor, Emad M.

2017-03-01

Monitoring of the membrane potential is possible using voltage sensitive dyes (VSD), where fluorescence intensity changes in response to neuronal electrical activity. However, fluorescence imaging is limited by depth of penetration and high scattering losses, which leads to low sensitivity in vivo systems for external detection. In contrast, photoacoustic (PA) imaging, an emerging modality, is capable of deep tissue, noninvasive imaging by combining near infrared light excitation and ultrasound detection. In this work, we develop the theoretical concept whereby the voltage-dependent quenching of dye fluorescence leads to a reciprocal enhancement of PA intensity. Based on this concept, we synthesized a novel near infrared photoacoustic VSD (PA-VSD) whose PA intensity change is sensitive to membrane potential. In the polarized state, this cyanine-based probe enhances PA intensity while decreasing fluorescence output in a lipid vesicle membrane model. With a 3-9 μM VSD concentration, we measured a PA signal increase in the range of 5.3 % to 18.1 %, and observed a corresponding signal reduction in fluorescence emission of 30.0 % to 48.7 %. A theoretical model successfully accounts for how the experimental PA intensity change depends on fluorescence and absorbance properties of the dye. These results not only demonstrate the voltage sensing capability of the dye, but also indicate the necessity of considering both fluorescence and absorbance spectral sensitivities in order to optimize the characteristics of improved photoacoustic probes. Together, our results demonstrate photoacoustic sensing as a potential new modality for sub-second recording and external imaging of electrophysiological and neurochemical events in the brain.

Pressure induced phase transition and elastic properties of cerium mono-nitride (CeN)

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

Yaduvanshi, Namrata, E-mail: namrata-yaduvanshi@yahoo.com; Singh, Sadhna

2016-05-23

In the present paper, we have investigated the high-pressure structural phase transition and elastic properties of cerium mono-nitride. We studied theoretically the structural properties of this compound (CeN) by using the improved interaction potential model (IIPM) approach. This compound exhibits first order crystallographic phase transition from NaCl (B{sub 1}) to tetragonal (BCT) phase at 37 GPa. The phase transition pressures and associated volume collapse obtained from present potential model (IIPM) show a good agreement with available theoretical data.

What theory, for whom and in which context? Reflections on the application of theory in the development and evaluation of complex population health interventions.

PubMed

Moore, Graham F; Evans, Rhiannon E

2017-12-01

Recent years have seen a growing emphasis on the value of building and testing middle range theory throughout the development and evaluation of complex population health interventions. We agree that a coherent theoretical basis for intervention development, and use of evaluation to test key causal assumptions and build theory, are crucial. However, in this editorial, we argue that such recommendations have often been operationalised in somewhat simplistic terms with potentially perverse consequences, and that an uncritical assumption that an intervention explicitly based on theory is inherently superior carries significant risks. We first argue that the drive for theory-based approaches may have exacerbated a propensity to select 'off-the-shelf' theories, leading to the selection of inappropriate theories which distract attention from the mechanisms through which a problem is actually sustained. Second, we discuss a tendency toward over-reliance on individual-level theorising. Finally, we discuss the relatively slow progress of population health intervention research in attending to issues of context, and the ecological fit of interventions with the systems whose functioning they attempt to change. We argue that while researchers should consider a broad range of potential theoretical perspectives on a given population health problem, citing a popular off-the-shelf theory as having informed an intervention and its evaluation does not inherently make for better science. Before identifying or developing a theory of change, researchers should develop a clear understanding of how the problem under consideration is created and sustained in context. A broader conceptualisation of theory that reaches across disciplines is vital if theory is to enhance, rather than constrain, the contribution of intervention research. Finally, intervention researchers need to move away from viewing interventions as discrete packages of components which can be described in isolation from their contexts, and better understand the systems into which change is being introduced.

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.

Long-range empirical potential model: extension to hexagonal close-packed metals.

PubMed

Dai, Y; Li, J H; Liu, B X

2009-09-23

An n-body potential is developed and satisfactorily applied to hcp metals, Co, Hf, Mg, Re, Ti, and Zr, in the form of long-range empirical potential. The potential can well reproduce the lattice constants, c/a ratios, cohesive energies, and the bulk modulus for their stable structures (hcp) and metastable structures (bcc or fcc). Meanwhile, the potential can correctly predict the order of structural stability and distinguish the energy differences between their stable hcp structure and other structures. The energies and forces derived by the potential can smoothly go to zero at cutoff radius, thus completely avoiding the unphysical behaviors in the simulations. The developed potential is applied to study the vacancy, surface fault, stacking fault and self-interstitial atom in the hcp metals. The calculated formation energies of vacancy and divacancy and activation energies of self-diffusion by vacancies are in good agreement with the values in experiments and in other works. The calculated surface energies and stacking fault energies are also consistent with the experimental data and those obtained in other theoretical works. The calculated formation energies generally agree with the results in other works, although the stable configurations of self-interstitial atoms predicted in this work somewhat contrast with those predicted by other methods. The proposed potential is shown to be relevant for describing the interaction of bcc, fcc and hcp metal systems, bringing great convenience for researchers in constructing potentials for metal systems constituted by any combination of bcc, fcc and hcp metals.

Magnetism in curved geometries

NASA Astrophysics Data System (ADS)

Streubel, Robert

Deterministically bending and twisting two-dimensional structures in the three-dimensional (3D) space provide means to modify conventional or to launch novel functionalities by tailoring curvature and 3D shape. The recent developments of 3D curved magnetic geometries, ranging from theoretical predictions over fabrication to characterization using integral means as well as advanced magnetic tomography, will be reviewed. Theoretical works predict a curvature-induced effective anisotropy and effective Dzyaloshinskii-Moriya interaction resulting in a vast of novel effects including magnetochiral effects (chirality symmetry breaking) and topologically induced magnetization patterning. The remarkable development of nanotechnology, e.g. preparation of high-quality extended thin films, nanowires and frameworks via chemical and physical deposition as well as 3D nano printing, has granted first insights into the fundamental properties of 3D shaped magnetic objects. Optimizing magnetic and structural properties of these novel 3D architectures demands new investigation methods, particularly those based on vector tomographic imaging. Magnetic neutron tomography and electron-based 3D imaging, such as electron holography and vector field electron tomography, are well-established techniques to investigate macroscopic and nanoscopic samples, respectively. At the mesoscale, the curved objects can be investigated using the novel method of magnetic X-ray tomography. In spite of experimental challenges to address the appealing theoretical predictions of curvature-induced effects, those 3D magnetic architectures have already proven their application potential for life sciences, targeted delivery, realization of 3D spin-wave filters, and magneto-encephalography devices, to name just a few. DOE BES MSED (DE-AC02-05-CH11231).

Conservation Physiology and Conservation Pathogens: White-Nose Syndrome and Integrative Biology for Host-Pathogen Systems.

PubMed

Willis, Craig K R

2015-10-01

Conservation physiology aims to apply an understanding of physiological mechanisms to management of imperiled species, populations, or ecosystems. One challenge for physiologists hoping to apply their expertise to conservation is connecting the mechanisms we study, often in the laboratory, with the vital rates of populations in the wild. There is growing appreciation that infectious pathogens can threaten populations and species, and represent an important issue for conservation. Conservation physiology has much to offer in terms of addressing the threat posed to some host species by infectious pathogens. At the same time, the well-developed theoretical framework of disease ecology could provide a model to help advance the application of physiology to a range of other conservation issues. Here, I use white-nose syndrome (WNS) in hibernating North American bats as an example of a conservation problem for which integrative physiological research has been a critical part of research and management. The response to WNS highlights the importance of a well-developed theoretical framework for the application of conservation physiology to a particular threat. I review what is known about physiological mechanisms associated with mortality from WNS and emphasize the value of combining a strong theoretical background with integrative physiological studies in order to connect physiological mechanisms with population processes and thereby maximize the potential benefits of conservation physiology. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

A theoretical signal processing framework for linear diffusion MRI: Implications for parameter estimation and experiment design.

PubMed

Varadarajan, Divya; Haldar, Justin P

2017-11-01

The data measured in diffusion MRI can be modeled as the Fourier transform of the Ensemble Average Propagator (EAP), a probability distribution that summarizes the molecular diffusion behavior of the spins within each voxel. This Fourier relationship is potentially advantageous because of the extensive theory that has been developed to characterize the sampling requirements, accuracy, and stability of linear Fourier reconstruction methods. However, existing diffusion MRI data sampling and signal estimation methods have largely been developed and tuned without the benefit of such theory, instead relying on approximations, intuition, and extensive empirical evaluation. This paper aims to address this discrepancy by introducing a novel theoretical signal processing framework for diffusion MRI. The new framework can be used to characterize arbitrary linear diffusion estimation methods with arbitrary q-space sampling, and can be used to theoretically evaluate and compare the accuracy, resolution, and noise-resilience of different data acquisition and parameter estimation techniques. The framework is based on the EAP, and makes very limited modeling assumptions. As a result, the approach can even provide new insight into the behavior of model-based linear diffusion estimation methods in contexts where the modeling assumptions are inaccurate. The practical usefulness of the proposed framework is illustrated using both simulated and real diffusion MRI data in applications such as choosing between different parameter estimation methods and choosing between different q-space sampling schemes. Copyright © 2017 Elsevier Inc. All rights reserved.

Theoretical Coalescence: A Method to Develop Qualitative Theory: The Example of Enduring.

PubMed

Morse, Janice M

Qualitative research is frequently context bound, lacks generalizability, and is limited in scope. The purpose of this article was to describe a method, theoretical coalescence, that provides a strategy for analyzing complex, high-level concepts and for developing generalizable theory. Theoretical coalescence is a method of theoretical expansion, inductive inquiry, of theory development, that uses data (rather than themes, categories, and published extracts of data) as the primary source for analysis. Here, using the development of the lay concept of enduring as an example, I explore the scientific development of the concept in multiple settings over many projects and link it within the Praxis Theory of Suffering. As comprehension emerges when conducting theoretical coalescence, it is essential that raw data from various different situations be available for reinterpretation/reanalysis and comparison to identify the essential features of the concept. The concept is then reconstructed, with additional inquiry that builds description, and evidence is conducted and conceptualized to create a more expansive concept and theory. By utilizing apparently diverse data sets from different contexts that are linked by certain characteristics, the essential features of the concept emerge. Such inquiry is divergent and less bound by context yet purposeful, logical, and with significant pragmatic implications for practice in nursing and beyond our discipline. Theoretical coalescence is a means by which qualitative inquiry is broadened to make an impact, to accommodate new theoretical shifts and concepts, and to make qualitative research applied and accessible in new ways.

Theoretical Coalescence: A Method to Develop Qualitative Theory

PubMed Central

Morse, Janice M.

2018-01-01

Background Qualitative research is frequently context bound, lacks generalizability, and is limited in scope. Objectives The purpose of this article was to describe a method, theoretical coalescence, that provides a strategy for analyzing complex, high-level concepts and for developing generalizable theory. Theoretical coalescence is a method of theoretical expansion, inductive inquiry, of theory development, that uses data (rather than themes, categories, and published extracts of data) as the primary source for analysis. Here, using the development of the lay concept of enduring as an example, I explore the scientific development of the concept in multiple settings over many projects and link it within the Praxis Theory of Suffering. Methods As comprehension emerges when conducting theoretical coalescence, it is essential that raw data from various different situations be available for reinterpretation/reanalysis and comparison to identify the essential features of the concept. The concept is then reconstructed, with additional inquiry that builds description, and evidence is conducted and conceptualized to create a more expansive concept and theory. Results By utilizing apparently diverse data sets from different contexts that are linked by certain characteristics, the essential features of the concept emerge. Such inquiry is divergent and less bound by context yet purposeful, logical, and with significant pragmatic implications for practice in nursing and beyond our discipline. Conclusion Theoretical coalescence is a means by which qualitative inquiry is broadened to make an impact, to accommodate new theoretical shifts and concepts, and to make qualitative research applied and accessible in new ways. PMID:29360688

Synthesis, tautomeric stability, spectroscopy and computational study of a potential molecular switch of (Z)-4-(phenylamino)pent-3-en-2-one

NASA Astrophysics Data System (ADS)

Fahid, Farzaneh; Kanaani, Ayoub; Pourmousavi, Seied Ali; Ajloo, Davood

2017-04-01

The (Z)-4-(phenylamino) pent-3-en-2-one (PAPO) was synthesised applying carbon-based solid acid and described by experimental techniques. Calculated results reveal that its keto-amine form is more stable than its enol-imine form. A relaxed potential energy surface scan has been accomplished based on the optimised geometry of NH tautomeric form to depict the potential energy barrier related to intramolecular proton transfer. The spectroscopic results and theoretical calculations demonstrate that the intramolecular hydrogen bonding strength of PAPO is stronger than that in 4-amino-3-penten-2-one)APO(. In addition, molecular electrostatic potential, total and partial density of stats (TDOS, PDOS) and non-linear optical properties of the compound were studied using same theoretical calculations. Our calculations show that the title molecule has the potential to be used as molecular switch.

Measuring team factors thought to influence the success of quality improvement in primary care: a systematic review of instruments

PubMed Central

2013-01-01

Background Measuring team factors in evaluations of Continuous Quality Improvement (CQI) may provide important information for enhancing CQI processes and outcomes; however, the large number of potentially relevant factors and associated measurement instruments makes inclusion of such measures challenging. This review aims to provide guidance on the selection of instruments for measuring team-level factors by systematically collating, categorizing, and reviewing quantitative self-report instruments. Methods Data sources: We searched MEDLINE, PsycINFO, and Health and Psychosocial Instruments; reference lists of systematic reviews; and citations and references of the main report of instruments. Study selection: To determine the scope of the review, we developed and used a conceptual framework designed to capture factors relevant to evaluating CQI in primary care (the InQuIRe framework). We included papers reporting development or use of an instrument measuring factors relevant to teamwork. Data extracted included instrument purpose; theoretical basis, constructs measured and definitions; development methods and assessment of measurement properties. Analysis and synthesis: We used qualitative analysis of instrument content and our initial framework to develop a taxonomy for summarizing and comparing instruments. Instrument content was categorized using the taxonomy, illustrating coverage of the InQuIRe framework. Methods of development and evidence of measurement properties were reviewed for instruments with potential for use in primary care. Results We identified 192 potentially relevant instruments, 170 of which were analyzed to develop the taxonomy. Eighty-one instruments measured constructs relevant to CQI teams in primary care, with content covering teamwork context (45 instruments measured enabling conditions or attitudes to teamwork), team process (57 instruments measured teamwork behaviors), and team outcomes (59 instruments measured perceptions of the team or its effectiveness). Forty instruments were included for full review, many with a strong theoretical basis. Evidence supporting measurement properties was limited. Conclusions Existing instruments cover many of the factors hypothesized to contribute to QI success. With further testing, use of these instruments measuring team factors in evaluations could aid our understanding of the influence of teamwork on CQI outcomes. Greater consistency in the factors measured and choice of measurement instruments is required to enable synthesis of findings for informing policy and practice. PMID:23410500

Number theoretical foundations in cryptography

NASA Astrophysics Data System (ADS)

Atan, Kamel Ariffin Mohd

2017-08-01

In recent times the hazards in relationships among entities in different establishments worldwide have generated exciting developments in cryptography. Central to this is the theory of numbers. This area of mathematics provides very rich source of fundamental materials for constructing secret codes. Some number theoretical concepts that have been very actively used in designing crypto systems will be highlighted in this presentation. This paper will begin with introduction to basic number theoretical concepts which for many years have been thought to have no practical applications. This will include several theoretical assertions that were discovered much earlier in the historical development of number theory. This will be followed by discussion on the "hidden" properties of these assertions that were later exploited by designers of cryptosystems in their quest for developing secret codes. This paper also highlights some earlier and existing cryptosystems and the role played by number theoretical concepts in their constructions. The role played by cryptanalysts in detecting weaknesses in the systems developed by cryptographers concludes this presentation.

New strategies to improve the efficacy of colorectal cancer vaccines: from bench to bedside.

PubMed

Mocellin, Simone

2006-12-01

By exploiting a naturally occurring defense system, anticancer vaccination embodies an ideal non-toxic treatment capable of evoking tumor-specific immune responses that can ultimately recognize and kill colorectal cancer (CRC) cells. Despite the enormous theoretical potential of active specific immunotherapy, no vaccination regimen has achieved sufficient therapeutic efficacy necessary for clinical implementation. Nevertheless, several immunological advances have opened new avenues of research to decipher the biological code governing tumor immune responsiveness, and this is leading to the design of potentially more effective immunotherapeutic protocols. This review briefly summarizes the principles behind anti-CRC vaccination and describes the most promising immunological strategies that have been developed, which are expected to renew interest in this molecularly targeted anticancer approach.

SPACER: server for predicting allosteric communication and effects of regulation

PubMed Central

Goncearenco, Alexander; Mitternacht, Simon; Yong, Taipang; Eisenhaber, Birgit; Eisenhaber, Frank; Berezovsky, Igor N.

2013-01-01

The SPACER server provides an interactive framework for exploring allosteric communication in proteins with different sizes, degrees of oligomerization and function. SPACER uses recently developed theoretical concepts based on the thermodynamic view of allostery. It proposes easily tractable and meaningful measures that allow users to analyze the effect of ligand binding on the intrinsic protein dynamics. The server shows potential allosteric sites and allows users to explore communication between the regulatory and functional sites. It is possible to explore, for instance, potential effector binding sites in a given structure as targets for allosteric drugs. As input, the server only requires a single structure. The server is freely available at http://allostery.bii.a-star.edu.sg/. PMID:23737445

Supersonic wings with significant leading-edge thrust at cruise

NASA Technical Reports Server (NTRS)

Robins, A. W.; Carlson, H. W.; Mack, R. J.

1980-01-01

Experimental/theoretical correlations are presented which show that significant levels of leading-edge thrust are possible at supersonic speeds for certain planforms having the geometry to support the theoretical thrust-distribution potential. The new analytical process employed provides not only the level of leading-edge thrust attainable but also the spanwise distribution of both it and that component of full theoretical thrust which acts as vortex lift. Significantly improved aerodynamic performance in the moderate supersonic speed regime is indicated.

Clear-water abutment and contraction scour in the Coastal Plain and Piedmont Provinces of South Carolina, 1996-99

USGS Publications Warehouse

Benedict, Stephen T.

2016-01-01

Data from this study have been compiled into a database that includes photographs, figures, observed scour depths, theoretical scour depths, limited basin characteristics, limited soil data, and theoretical hydraulic data. The database can be used to compare studied sites with unstudied sites to assess the potential for scour at the unstudied sites. In addition, the database can be used to assess the performance of various theoretical methods for predicting clear-water abutment and contraction scour.

Prediction and theoretical characterization of p-type organic semiconductor crystals for field-effect transistor applications.

PubMed

Atahan-Evrenk, Sule; Aspuru-Guzik, Alán

2014-01-01

The theoretical prediction and characterization of the solid-state structure of organic semiconductors has tremendous potential for the discovery of new high performance materials. To date, the theoretical analysis mostly relied on the availability of crystal structures obtained through X-ray diffraction. However, the theoretical prediction of the crystal structures of organic semiconductor molecules remains a challenge. This review highlights some of the recent advances in the determination of structure-property relationships of the known organic semiconductor single-crystals and summarizes a few available studies on the prediction of the crystal structures of p-type organic semiconductors for transistor applications.

Development of a Strontium Magneto-Optical Trap for Probing Casimir-Polder Potentials

NASA Astrophysics Data System (ADS)

Martin, Paul J.

In recent years, cold atoms have been the centerpiece of many remarkably sensitive measurements, and much effort has been made to devise miniaturized quantum sensors and quantum information processing devices. At small distances, however, mechanical effects of the quantum vacuum begin to significantly impact the behavior of the cold-atom systems. A better understanding of how surface composition and geometry affect Casimir and Casimir-Polder potentials would benefit future engineering of small-scale devices. Unfortunately, theoretical solutions are limited and the number of experimental techniques that can accurately detect such short-range forces is relatively small. We believe the exemplary properties of atomic strontium--which have enabled unprecedented frequency metrology in optical lattice clocks--make it an ideal candidate for probing slight spectroscopic perturbations caused by vacuum fluctuations. To that end, we have constructed a magneto-optical trap for strontium to enable future study of atom-surface potentials, and the apparatus and proposed detection scheme are discussed herein. Of special note is a passively stable external-cavity diode laser we developed that is both affordable and competitive with high-end commercial options.

Sizing up human health through remote sensing: uses and misuses.

PubMed

Herbreteau, V; Salem, G; Souris, M; Hugot, J P; Gonzalez, J P

2005-03-01

Following the launch of new satellites, remote sensing (RS) has been increasingly implicated in human health research for thirty years, providing a growing availability of images with higher resolution and spectral ranges. However, the scope of applications, beyond theoretical large potentialities, appears limited both by their technical nature and the models developed. An exhaustive review of RS applications in human health highlights the real implication thus far regarding the diversity and range of health issues, remotely sensed data, processes and interpretations. The place of RS is far under its expected potential, revealing fundamental barriers in its implementation for health applications. The selection of images is done by practical considerations as trivial as price and availability, which are often not relevant to addressing health questions requiring suitable resolutions and spatio-temporal range. The relationships of environmental variables from RS, geospatial data from other sources for health investigations are poorly addressed and usually simplified. A discussion covering the potential of RS for human health is developed here to assist health scientists deal with spatial and temporal dynamics of health, by finding the most relevant data and analysis procedures.

Finite element model for MOI applications using A-V formulation

NASA Astrophysics Data System (ADS)

Xuan, L.; Shanker, B.; Udpa, L.; Shih, W.; Fitzpatrick, G.

2001-04-01

Magneto-optic imaging (MOI) is a relatively new sensor application of an extension of bubble memory technology to NDT and produce easy-to-interpret, real time analog images. MOI systems use a magneto-optic (MO) sensor to produce analog images of magnetic flux leakage from surface and subsurface defects. The instrument's capability in detecting the relatively weak magnetic fields associated with subsurface defects depends on the sensitivity of the magneto-optic sensor. The availability of a theoretical model that can simulate the MOI system performance is extremely important for optimization of the MOI sensor and hardware system. A nodal finite element model based on magnetic vector potential formulation has been developed for simulating MOI phenomenon. This model has been used for predicting the magnetic fields in simple test geometry with corrosion dome defects. In the case of test samples with multiple discontinuities, a more robust model using the magnetic vector potential Ā and electrical scalar potential V is required. In this paper, a finite element model based on A-V formulation is developed to model complex circumferential crack under aluminum rivets in dimpled countersink.

Analysis and development of adjoint-based h-adaptive direct discontinuous Galerkin method for the compressible Navier-Stokes equations

NASA Astrophysics Data System (ADS)

Cheng, Jian; Yue, Huiqiang; Yu, Shengjiao; Liu, Tiegang

2018-06-01

In this paper, an adjoint-based high-order h-adaptive direct discontinuous Galerkin method is developed and analyzed for the two dimensional steady state compressible Navier-Stokes equations. Particular emphasis is devoted to the analysis of the adjoint consistency for three different direct discontinuous Galerkin discretizations: including the original direct discontinuous Galerkin method (DDG), the direct discontinuous Galerkin method with interface correction (DDG(IC)) and the symmetric direct discontinuous Galerkin method (SDDG). Theoretical analysis shows the extra interface correction term adopted in the DDG(IC) method and the SDDG method plays a key role in preserving the adjoint consistency. To be specific, for the model problem considered in this work, we prove that the original DDG method is not adjoint consistent, while the DDG(IC) method and the SDDG method can be adjoint consistent with appropriate treatment of boundary conditions and correct modifications towards the underlying output functionals. The performance of those three DDG methods is carefully investigated and evaluated through typical test cases. Based on the theoretical analysis, an adjoint-based h-adaptive DDG(IC) method is further developed and evaluated, numerical experiment shows its potential in the applications of adjoint-based adaptation for simulating compressible flows.

Design and Development of a Model to Simulate 0-G Treadmill Running Using the European Space Agency's Subject Loading System

NASA Technical Reports Server (NTRS)

Caldwell, E. C.; Cowley, M. S.; Scott-Pandorf, M. M.

2010-01-01

Develop a model that simulates a human running in 0 G using the European Space Agency s (ESA) Subject Loading System (SLS). The model provides ground reaction forces (GRF) based on speed and pull-down forces (PDF). DESIGN The theoretical basis for the Running Model was based on a simple spring-mass model. The dynamic properties of the spring-mass model express theoretical vertical GRF (GRFv) and shear GRF in the posterior-anterior direction (GRFsh) during running gait. ADAMs VIEW software was used to build the model, which has a pelvis, thigh segment, shank segment, and a spring foot (see Figure 1).the model s movement simulates the joint kinematics of a human running at Earth gravity with the aim of generating GRF data. DEVELOPMENT & VERIFICATION ESA provided parabolic flight data of subjects running while using the SLS, for further characterization of the model s GRF. Peak GRF data were fit to a linear regression line dependent on PDF and speed. Interpolation and extrapolation of the regression equation provided a theoretical data matrix, which is used to drive the model s motion equations. Verification of the model was conducted by running the model at 4 different speeds, with each speed accounting for 3 different PDF. The model s GRF data fell within a 1-standard-deviation boundary derived from the empirical ESA data. CONCLUSION The Running Model aids in conducting various simulations (potential scenarios include a fatigued runner or a powerful runner generating high loads at a fast cadence) to determine limitations for the T2 vibration isolation system (VIS) aboard the International Space Station. This model can predict how running with the ESA SLS affects the T2 VIS and may be used for other exercise analyses in the future.

Beyond the rhetoric: what do we mean by a 'model of care'?

PubMed

Davidson, Patricia; Halcomb, Elizabeth; Hickman, L; Phillips, J; Graham, B

2006-01-01

Contemporary health care systems are constantly challenged to revise traditional methods of health care delivery. These challenges are multifaceted and stem from: (1) novel pharmacological and non-pharmacological treatments; (2) changes in consumer demands and expectations; (3) fiscal and resource constraints; (4) changes in societal demographics in particular the ageing of society; (5) an increasing burden of chronic disease; (6) documentation of limitations in traditional health care delivery; (7) increased emphasis on transparency, accountability, evidence-based practice (EBP) and clinical governance structures; and (8) the increasing cultural diversity of the community. These challenges provoke discussion of potential alternative models of care, with scant reference to defining what constitutes a model of care. This paper aims to define what is meant by the term 'model of care' and document the pragmatic systems and processes necessary to develop, plan, implement and evaluate novel models of care delivery. Searches of electronic databases, the reference lists of published materials, policy documents and the Internet were conducted using key words including 'model*', 'framework*', 'models, theoretical' and 'nursing models, theoretical'. The collated material was then analysed and synthesised into this review. This review determined that in addition to key conceptual and theoretical perspectives, quality improvement theory (eg. collaborative methodology), project management methods and change management theory inform both pragmatic and conceptual elements of a model of care. Crucial elements in changing health care delivery through the development of innovative models of care include the planning, development, implementation, evaluation and assessment of the sustainability of the new model. Regardless of whether change in health care delivery is attempted on a micro basis (eg. ward level) or macro basis (eg. national or state system) in order to achieve sustainable, effective and efficient changes a well-planned, systematic process is essential.

Anesthesiologists' and surgeons' perceptions about routine pre-operative testing in low-risk patients: application of the Theoretical Domains Framework (TDF) to identify factors that influence physicians' decisions to order pre-operative tests.

PubMed

Patey, Andrea M; Islam, Rafat; Francis, Jill J; Bryson, Gregory L; Grimshaw, Jeremy M

2012-06-09

Routine pre-operative tests for anesthesia management are often ordered by both anesthesiologists and surgeons for healthy patients undergoing low-risk surgery. The Theoretical Domains Framework (TDF) was developed to investigate determinants of behaviour and identify potential behaviour change interventions. In this study, the TDF is used to explore anaesthesiologists' and surgeons' perceptions of ordering routine tests for healthy patients undergoing low-risk surgery. Sixteen clinicians (eleven anesthesiologists and five surgeons) throughout Ontario were recruited. An interview guide based on the TDF was developed to identify beliefs about pre-operative testing practices. Content analysis of physicians' statements into the relevant theoretical domains was performed. Specific beliefs were identified by grouping similar utterances of the interview participants. Relevant domains were identified by noting the frequencies of the beliefs reported, presence of conflicting beliefs, and perceived influence on the performance of the behaviour under investigation. Seven of the twelve domains were identified as likely relevant to changing clinicians' behaviour about pre-operative test ordering for anesthesia management. Key beliefs were identified within these domains including: conflicting comments about who was responsible for the test-ordering (Social/professional role and identity); inability to cancel tests ordered by fellow physicians (Beliefs about capabilities and social influences); and the problem with tests being completed before the anesthesiologists see the patient (Beliefs about capabilities and Environmental context and resources). Often, tests were ordered by an anesthesiologist based on who may be the attending anesthesiologist on the day of surgery while surgeons ordered tests they thought anesthesiologists may need (Social influences). There were also conflicting comments about the potential consequences associated with reducing testing, from negative (delay or cancel patients' surgeries), to indifference (little or no change in patient outcomes), to positive (save money, avoid unnecessary investigations) (Beliefs about consequences). Further, while most agreed that they are motivated to reduce ordering unnecessary tests (Motivation and goals), there was still a report of a gap between their motivation and practice (Behavioural regulation). We identified key factors that anesthesiologists and surgeons believe influence whether they order pre-operative tests routinely for anesthesia management for a healthy adults undergoing low-risk surgery. These beliefs identify potential individual, team, and organisation targets for behaviour change interventions to reduce unnecessary routine test ordering.

Artificial evolution: a new path for artificial intelligence?

PubMed

Husbands, P; Harvey, I; Cliff, D; Miller, G

1997-06-01

Recently there have been a number of proposals for the use of artificial evolution as a radically new approach to the development of control systems for autonomous robots. This paper explains the artificial evolution approach, using work at Sussex to illustrate it. The paper revolves around a case study on the concurrent evolution of control networks and visual sensor morphologies for a mobile robot. Wider intellectual issues surrounding the work are discussed, as is the use of more abstract evolutionary simulations as a new potentially useful tool in theoretical biology.

Floquet-Network Theory of Nonreciprocal Transport

NASA Astrophysics Data System (ADS)

Li, Huanan; Kottos, Tsampikos; Shapiro, Boris

2018-04-01

We develop a theoretical framework that lays out the fundamental rules under which a periodic (Floquet) driving scheme can induce nonreciprocal transport. Our approach utilizes an extended Hilbert space where a Floquet network with an extra (frequency) dimension naturally arises. The properties of this network (its on-site potential and the intersite couplings) are in one-to-one correspondence with the initial driving scheme. Its proper design allows for a control of the multipath scattering processes and the associated interferences. We harness this degree of freedom to realize driving schemes with narrow-band or broadband nonreciprocal transport.

Achieving Weak Light Response with Plasmonic Nanogold-Decorated Organic Phototransistors.

PubMed

Luo, Xiao; Du, Lili; Liang, Yuanlong; Zhao, Feiyu; Lv, Wenli; Xu, Kun; Wang, Ying; Peng, Yingquan

2018-05-09

Weak light response of organic photodetectors has fascinating potentials in fields of modern science and technology. However, their photoresponsivity is hindered by poor photocarrier excitation and transport. Decorating active-layer surface with plasmonic nanometals is considered a viable strategy to address this issue. Here, we demonstrate a plasmonic nanogold decorated organic phototransistor achieving remarkable enhancement of photoresponsivity. Meanwhile, the photoresponsive range is broadened by 4 orders of magnitude. The proposed design is substantiated by a schematic energy level model combined with theoretical simulation analysis, enabling the development of the advanced optoelectronics.

Empirical Analysis of Human Capital, Learning Culture, and Knowledge Management as Antecedents to Organizational Performance: Theoretical and Practical Implications for Logistics Readiness Officer Force Development

DTIC Science & Technology

2014-03-27

Much of the DoD’s force shaping problems in the active duty military stem from the way in which it chose to absorb the force reductions at the end...indicated the need for more joint oriented education and training to help them in the performance of their primary duties. CLL 016 (Joint Logistics... CLL 054 (Joint Task Force Port Opening) and CLL 055 (Joint Deployment and Distribution Performance Metrics Framework) all received high potential

Fluid Dynamic and Stability Analysis of a Thin Liquid Sheet

NASA Technical Reports Server (NTRS)

McMaster, Matthew S.

1992-01-01

Interest in thin sheet flows has recently been renewed due to their potential application in space radiators. Theoretical and experimental studies of the fluid dynamics and stability of thin liquid sheet flows have been carried out in this thesis. A computer program was developed to determine the cross-sectional shape of the edge cylinder given the cross-sectional area of the edge cylinder. A stability analysis was performed on a non-planer liquid sheet. A study was conducted to determine the effects of air resistance on the sheet.

Creating Good Employment Opportunities for the Rural Sector

PubMed Central

Foster, Andrew D.

2013-01-01

This paper examines the potential for sector-specific productivity growth, human capital, credit markets, and infrastructure to contribute to the development of stable, well-paid employment in rural areas of low-income countries. Particular emphasis is placed on the way that different sectors of the rural economy interact with each other and with local and regional product markets. A simple theoretical framework and descriptive analysis of panel data from India suggests that more emphasis should be placed on increasing the production of goods that incorporate local agricultural products as inputs. PMID:25883938

Theoretical Perspectives on Gender in Education: The Case of Eastern and Southern Africa

NASA Astrophysics Data System (ADS)

Mannathoko, Changu

1999-11-01

In recent years, throughout Eastern and Southern Africa, there has been a proliferation of research on gender in education. It is possible to point to a wide variety of publications, courses and programmes planned and organized by universities, national governments, international organizations, non-governmental organizations and the private sector relating to this field. This article examines the feminist and gender theories underpinning all these endeavors. The theories are assessed for their potential capacity to assist in elucidating the complex relationship between gender and development within the region.

Inverse kinematics of a dual linear actuator pitch/roll heliostat

NASA Astrophysics Data System (ADS)

Freeman, Joshua; Shankar, Balakrishnan; Sundaram, Ganesh

2017-06-01

This work presents a simple, computationally efficient inverse kinematics solution for a pitch/roll heliostat using two linear actuators. The heliostat design and kinematics have been developed, modeled and tested using computer simulation software. A physical heliostat prototype was fabricated to validate the theoretical computations and data. Pitch/roll heliostats have numerous advantages including reduced cost potential and reduced space requirements, with a primary disadvantage being the significantly more complicated kinematics, which are solved here. Novel methods are applied to simplify the inverse kinematics problem which could be applied to other similar problems.

The Role of Identity in Acculturation among Immigrant People: Theoretical Propositions, Empirical Questions, and Applied Recommendations

ERIC Educational Resources Information Center

Schwartz, Seth J.; Montgomery, Marilyn J.; Briones, Ervin

2006-01-01

The present paper advances theoretical propositions regarding the relationship between acculturation and identity. The most central thesis argued is that acculturation represents changes in cultural identity and that personal identity has the potential to "anchor" immigrant people during their transition to a new society. The article emphasizes…

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…

Integrated Media: Toward a Theoretical Framework for Utilizing Their Potential.

ERIC Educational Resources Information Center

Journal of Special Education Technology, 1993

1993-01-01

This article discusses how current theories of learning and memory can guide the application of integrated media (IM) to embellish a standard curriculum; considers theoretical reasons for "breaking the mold"; and offers examples of IM-based alternatives to curricula in the areas of adult literacy, language arts, social studies, language skills,…

Sweat Therapy Theory, Practice, and Efficacy

ERIC Educational Resources Information Center

Eason, Allen; Colmant, Stephen; Winterowd, Carrie

2009-01-01

The purpose of this article is to examine the potential application of sweat rituals to group counseling, adventure therapy, and other forms of group work by describing a theoretical model for how sweat rituals work and presenting the results of a randomized comparative outcome study on the efficacy of sweat therapy. The theoretical model proposes…

A Theoretically Grounded Framework for Integrating the Scholarship of Teaching and Learning

ERIC Educational Resources Information Center

Walls, Jill K.

2016-01-01

SoTL scholars have written about the importance and utility of teaching from a guiding theoretical framework. In this paper, ecological theory and specifically Bronfenbrenner's bioecological model, is examined as a potential framework for synthesizing SoTL research findings to inform teaching and learning scholarship at the college level. A…

Synthesis, spectroscopic and structural characterization of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine with theoretical calculations using density functional theory.

PubMed

Inkaya, Ersin; Dinçer, Muharrem; Sahan, Emine; Yıldırım, Ismail

2013-10-01

In this paper, we will report a combined experimental and theoretical investigation of the molecular structure and spectroscopic parameters (FT-IR, (1)H NMR, (13)C NMR) of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine. The compound crystallizes in the triclinic space group P-1 with Z=2. The molecular geometry was also optimized using density functional theory (DFT/B3LYP) method with the 6-311G(d,p) and 6-311++G(d,p) basis sets in ground state and compared with the experimental data. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecules has been obtained by mapping electron density isosurface with electrostatic potential (ESP). Also, non-linear optical properties of the title compound were performed at B3LYP/6-311++G(d,p) level. The theoretical results showed an excellent agreement with the experimental values. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis, spectroscopic and structural characterization of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine with theoretical calculations using density functional theory

NASA Astrophysics Data System (ADS)

İnkaya, Ersin; Dinçer, Muharrem; Şahan, Emine; Yıldırım, İsmail

2013-10-01

In this paper, we will report a combined experimental and theoretical investigation of the molecular structure and spectroscopic parameters (FT-IR, 1H NMR, 13C NMR) of 5-benzoyl-4-phenyl-2-methylthio-1H-pyrimidine. The compound crystallizes in the triclinic space group P-1 with Z = 2. The molecular geometry was also optimized using density functional theory (DFT/B3LYP) method with the 6-311G(d,p) and 6-311++G(d,p) basis sets in ground state and compared with the experimental data. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecules has been obtained by mapping electron density isosurface with electrostatic potential (ESP). Also, non-linear optical properties of the title compound were performed at B3LYP/6-311++G(d,p) level. The theoretical results showed an excellent agreement with the experimental values.

Physical Violence between Siblings: A Theoretical and Empirical Analysis

ERIC Educational Resources Information Center

Hoffman, Kristi L.; Kiecolt, K. Jill; Edwards, John N.

2005-01-01

This study develops and tests a theoretical model to explain sibling violence based on the feminist, conflict, and social learning theoretical perspectives and research in psychology and sociology. A multivariate analysis of data from 651 young adults generally supports hypotheses from all three theoretical perspectives. Males with brothers have…

[Projection of prisoner numbers].

PubMed

Metz, Rainer; Sohn, Werner

2015-01-01

The past and future development of occupancy rates in prisons is of crucial importance for the judicial administration of every country. Basic factors for planning the required penal facilities are seasonal fluctuations, minimum, maximum and average occupancy as well as the present situation and potential development of certain imprisonment categories. As the prisoner number of a country is determined by a complex set of interdependent conditions, it has turned out to be difficult to provide any theoretical explanations. The idea accepted in criminology for a long time that prisoner numbers are interdependent with criminal policy must be regarded as having failed. Statistical and time series analyses may help, however, to identify the factors having influenced the development of prisoner numbers in the past. The analyses presented here, first describe such influencing factors from a criminological perspective and then deal with their statistical identification and modelling. Using the development of prisoner numbers in Hesse as an example, it has been found that modelling methods in which the independent variables predict the dependent variable with a time lag are particularly helpful. A potential complication is, however, that for predicting the number of prisoners the different dynamics in German and foreign prisoners require the development of further models.

The evolution of public relations and the use of the internet: the implications for health care organizations.

PubMed

Berkowitz, Eric N

2007-01-01

Over the past several years the discipline and practice of public relations has evolved. Historically, this field within health care organizations was a one-way management of communications and often was reactive in nature dealing with a crisis situation with an organization. Recent theoretical development within the discipline suggests that public relations involves more relationship building with key constituencies and on-going-dialogue. Concomitant with this evolution is the technological development of the internet. Most particularly is the use of podcasting and blogging as key tools which have been underutilized by health car providers but have significant potential in both communication and relationship opportunities as discussed in this article.

[The application of metabonomics in modern studies of Chinese materia medica].

PubMed

Chen, Hai-Bin; Zhou, Hong-Guang; Yu, Xiao-Yi

2012-06-01

Metabonomics, a newly developing subject secondary to genomics, transcriptomics, and proteomics, is an important constituent part of systems biology. It is believed to be the final direction of the systems biology. It can be directly applied to understand the physiological and biochemical states by its "metabolome profile" as a whole. Therefore, it can provide a huge amount of information different from those originating from other "omics". In the modernization of Chinese materia medica research, the application of metabonomics methods and technologies has a broad potential for future development. Especially it is of important theoretical significance and application value in holistic efficacies evaluation, active ingredients studies, and safety research of Chinese materia medica.

Socioeconomic Status, Family Processes, and Individual Development

PubMed Central

Conger, Rand D.; Conger, Katherine J.; Martin, Monica J.

2010-01-01

Research during the past decade shows that social class or socioeconomic status (SES) is related to satisfaction and stability in romantic unions, the quality of parent-child relationships, and a range of developmental outcomes for adults and children. This review focuses on evidence regarding potential mechanisms proposed to account for these associations. Research findings reported during the past decade demonstrate support for an interactionist model of the relationship between SES and family life, which incorporates assumptions from both the social causation and social selection perspectives. The review concludes with recommendations for future research on SES, family processes and individual development in terms of important theoretical and methodological issues yet to be addressed. PMID:20676350

Development of a severe local storm prediction system: A 60-day test of a mesoscale primitive equation model

NASA Technical Reports Server (NTRS)

Paine, D. A.; Zack, J. W.; Kaplan, M. L.

1979-01-01

The progress and problems associated with the dynamical forecast system which was developed to predict severe storms are examined. The meteorological problem of severe convective storm forecasting is reviewed. The cascade hypothesis which forms the theoretical core of the nested grid dynamical numerical modelling system is described. The dynamical and numerical structure of the model used during the 1978 test period is presented and a preliminary description of a proposed multigrid system for future experiments and tests is provided. Six cases from the spring of 1978 are discussed to illustrate the model's performance and its problems. Potential solutions to the problems are examined.

Getting the message across: does the use of drama aid education in palliative care?

PubMed

O'Connor, Margaret; Abbott, Jo-Anne; Recoche, Katrina

2012-05-01

Drama is a promising means of delivering educational messages in palliative care. Research studies have found drama to be an effective means of delivering educational messages in other domains of learning, such as teaching health education to children and adults and engaging the general public in health policy development. This paper discusses the potential of drama for palliative care education and provides an example of the use of a drama to deliver messages about death and dying at a conference on palliative care. The paper suggests a theoretical framework for how future drama productions could be developed to educate the community, health professionals and students about palliative care.

Ancient Ethical Practices of Dualism and Ethical Implications for Future Paradigms in Nursing.

PubMed

Milton, Constance L

2016-07-01

Paradigms contain theoretical structures to guide scientific disciplines. Since ancient times, Cartesian dualism has been a prominent philosophy incorporated in the practice of medicine. The discipline of nursing has continued the body-mind emphasis with similar paradigmatic thinking and theories of nursing that separate body and mind. Future trends for paradigm and nursing theory development are harkening to former ways of thinking. In this article the author discusses the origins of Cartesian dualism and implications for its current usage. The author shall illuminate what it potentially means to engage in dualism in nursing and discuss possible ethical implications for future paradigm and theory development in nursing. © The Author(s) 2016.

The interpersonal relationship in clinical practice. The Barrett-Lennard Relationship Inventory as an assessment instrument.

PubMed

Simmons, J; Roberge, L; Kendrick, S B; Richards, B

1995-03-01

The biomedical model that has long been central to medical practice is gradually being expanded to a broader biopsychosocial model. Relationship-building skills commensurate with the new paradigm need to be understood by educators and taught to medical practitioners. The person-centered, or humanistic, model of psychologist Carl Rogers provides a theoretical approach for the development of effective biopsychosocial relationships. The Barrett-Lennard Relationship Inventory (BLRI) was developed in 1962 as an assessment instrument for the person-centered model. In this article, the person-centered model and the use of the BLRI as an assessment instrument of this model are discussed. Current and potential uses of the BLRI are explored.

Evaluation of Learning Materials: A Holistic Framework

ERIC Educational Resources Information Center

Bundsgaard, Jeppe; Hansen, Thomas Illum

2011-01-01

This paper presents a holistic framework for evaluating learning materials and designs for learning. A holistic evaluation comprises investigations of the potential learning potential, the actualised learning potential, and the actual learning. Each aspect is explained and exemplified through theoretical models and definitions. (Contains 3 figures…

A theoretical study of the adiabatic and vertical ionization potentials of water.

PubMed

Feller, David; Davidson, Ernest R

2018-06-21

Theoretical predictions of the three lowest adiabatic and vertical ionization potentials of water were obtained from the Feller-Peterson-Dixon approach. This approach combines multiple levels of coupled cluster theory with basis sets as large as aug-cc-pV8Z in some cases and various corrections up to and including full configuration interaction theory. While agreement with experiment for the adiabatic ionization potential of the lowest energy 2 B 1 state was excellent, differences for other states were much larger, sometimes exceeding 10 kcal/mol (0.43 eV). Errors of this magnitude are inconsistent with previous benchmark work on 52 adiabatic ionization potentials, where a root mean square of 0.20 kcal/mol (0.009 eV) was found. Difficulties in direct comparisons between theory and experiment for vertical ionization potentials are discussed. With regard to the differences found for the 2 A 1 / 2 Π u and 2 B 2 adiabatic ionization potentials, a reinterpretation of the experimental spectrum appears justified.

Self-energy effect and Coulomb potential modulation of the exciton in monolayer MoS2 on polar substrate

NASA Astrophysics Data System (ADS)

Wang, Zi-Wu; Xiao, Yao; Li, Run-Ze; Li, Wei-Ping; Li, Zhi-Qing

2017-11-01

We theoretically investigate the correction of exciton binding energy in monolayer MoS2 resulting from the exciton couples with surface optical (SO) phonons induced by polar substrate. The total correction of binding energy can be divided into the self-energy effect and modification of Coulomb potential using the unitary transformation method. We find that both the self-energy and Coulomb potential vary from tens of meV to several hundreds of meV depending on the cut-off wave vector of SO phonon modes, polarizability of substrate materials and internal distance between the monolayer MoS2 and polar substrate. An effective Coulomb potential is obtained by combining the modified term into the Coulomb potential. This potentially could be widely used in various two-dimensional materials. Our theoretical results not only propose the ways to externally control the exciton binding energy in experiment, but also enrich the understanding of the exciton properties in the dielectric environment.

Study of Fission Barrier Heights of Uranium Isotopes by the Macroscopic-Microscopic Method

NASA Astrophysics Data System (ADS)

Zhong, Chun-Lai; Fan, Tie-Shuan

2014-09-01

Potential energy surfaces of uranium nuclei in the range of mass numbers 229 through 244 are investigated in the framework of the macroscopic-microscopic model and the heights of static fission barriers are obtained in terms of a double-humped structure. The macroscopic part of the nuclear energy is calculated according to Lublin—Strasbourg-drop (LSD) model. Shell and pairing corrections as the microscopic part are calculated with a folded-Yukawa single-particle potential. The calculation is carried out in a five-dimensional parameter space of the generalized Lawrence shapes. In order to extract saddle points on the potential energy surface, a new algorithm which can effectively find an optimal fission path leading from the ground state to the scission point is developed. The comparison of our results with available experimental data and others' theoretical results confirms the reliability of our calculations.

Assessing musical skills in autistic children who are not savants.

PubMed

Heaton, Pamela

2009-05-27

Descriptions of autistic musical savants suggest that they possess extraordinary skills within the domain. However, until recently little was known about the musical skills and potential of individuals with autism who are not savants. The results from these more recent studies investigating music perception, cognition and learning in musically untrained children with autism have revealed a pattern of abilities that are either enhanced or spared. For example, increased sensitivity to musical pitch and timbre is frequently observed, and studies investigating perception of musical structure and emotions have consistently failed to reveal deficits in autism. While the phenomenon of the savant syndrome is of considerable theoretical interest, it may have led to an under-consideration of the potential talents and skills of that vast majority of autistic individuals, who do not meet savant criteria. Data from empirical studies show that many autistic children possess musical potential that can and should be developed.

Assessing musical skills in autistic children who are not savants

PubMed Central

Heaton, Pamela

2009-01-01

Descriptions of autistic musical savants suggest that they possess extraordinary skills within the domain. However, until recently little was known about the musical skills and potential of individuals with autism who are not savants. The results from these more recent studies investigating music perception, cognition and learning in musically untrained children with autism have revealed a pattern of abilities that are either enhanced or spared. For example, increased sensitivity to musical pitch and timbre is frequently observed, and studies investigating perception of musical structure and emotions have consistently failed to reveal deficits in autism. While the phenomenon of the savant syndrome is of considerable theoretical interest, it may have led to an under-consideration of the potential talents and skills of that vast majority of autistic individuals, who do not meet savant criteria. Data from empirical studies show that many autistic children possess musical potential that can and should be developed. PMID:19528029

Suppressing Klein tunneling in graphene using a one-dimensional array of localized scatterers.

PubMed

Walls, Jamie D; Hadad, Daniel

2015-02-13

Graphene's unique physical and chemical properties make it an attractive platform for use in micro- and nanoelectronic devices. However, electrostatically controlling the flow of electrons in graphene can be challenging as a result of Klein tunneling, where electrons normally incident to a one-dimensional potential barrier of height V are perfectly transmitted even as V → ∞. In this study, theoretical and numerical calculations predict that the transmission probability for an electron wave normally incident to a one-dimensional array of localized scatterers can be significantly less than unity when the electron wavelength is smaller than the spacing between scatterers. In effect, placing periodic openings throughout a potential barrier can, somewhat counterintuitively, decrease transmission in graphene. Our results suggest that electrostatic potentials with spatial variations on the order of the electron wavelength can suppress Klein tunneling and could find applications in developing graphene electronic devices.

From lists of behaviour change techniques (BCTs) to structured hierarchies: comparison of two methods of developing a hierarchy of BCTs.

PubMed

Cane, James; Richardson, Michelle; Johnston, Marie; Ladha, Ruhina; Michie, Susan

2015-02-01

Behaviour change technique (BCT) Taxonomy v1 is a hierarchically grouped, consensus-based taxonomy of 93 BCTs for reporting intervention content. To enhance the use and understanding of BCTs, the aims of the present study were to (1) quantitatively examine the 'bottom-up' hierarchical structure of Taxonomy v1, (2) identify whether BCTs can be reliably mapped to theoretical domains using a 'top-down' theoretically driven approach, and (3) identify any overlap between the 'bottom-up' and 'top-down' groupings. The 'bottom-up' structure was examined for higher-order groupings using a dendrogram derived from hierarchical cluster analysis. For the theory-based 'top-down' structure, 18 experts sorted BCTs into 14 theoretical domains. Discriminant Content Validity was used to identify groupings, and chi-square tests and Pearson's residuals were used to examine the overlap between groupings. Behaviour change techniques relating to 'Reward and Punishment' and 'Cues and Cue Responses' were perceived as markedly different to other BCTs. Fifty-nine of the BCTs were reliably allocated to 12 of the 14 theoretical domains; 47 were significant and 12 were of borderline significance. Thirty-four of 208 'bottom-up' × 'top-down' pairings showed greater overlap than expected by chance. However, only six combinations achieved satisfactory evidence of similarity. The moderate overlap between the groupings indicates some tendency to implicitly conceptualize BCTs in terms of the same theoretical domains. Understanding the nature of the overlap will aid the conceptualization of BCTs in terms of theory and application. Further research into different methods of developing a hierarchical taxonomic structure of BCTs for international, interdisciplinary work is now required. Statement of contribution What is already known on this subject? Behaviour change interventions are effective in improving health care and health outcomes. The 'active' components of these interventions are behaviour change techniques and over 93 have been identified. Taxonomies of behaviour change techniques require structure to enable potential applications. What does this study add? This study identifies groups of BCTs to aid the recall of BCTs for intervention coding and design. It compares two methods of grouping--'bottom-up' and theory-based 'top-down'--and finds a moderate overlap. Building on identified BCT groups, it examines relationships between theoretical domains and BCTs. © 2014 The British Psychological Society.

Iso standardization of theoretical activity evaluation method for low and intermediate level activated waste generated at nuclear power plants

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

Makoto Kashiwagi; Garamszeghy, Mike; Lantes, Bertrand

Disposal of low-and intermediate-level activated waste generated at nuclear power plants is being planned or carried out in many countries. The radioactivity concentrations and/or total quantities of long-lived, difficult-to-measure nuclides (DTM nuclides), such as C-14, Ni-63, Nb-94, α emitting nuclides etc., are often restricted by the safety case for a final repository as determined by each country's safety regulations, and these concentrations or amounts are required to be known and declared. With respect to waste contaminated by contact with process water, the Scaling Factor method (SF method), which is empirically based on sampling and analysis data, has been applied asmore » an important method for determining concentrations of DTM nuclides. This method was standardized by the International Organization for Standardization (ISO) and published in 2007 as ISO21238 'Scaling factor method to determine the radioactivity of low and intermediate-level radioactive waste packages generated at nuclear power plants' [1]. However, for activated metal waste with comparatively high concentrations of radioactivity, such as may be found in reactor control rods and internal structures, direct sampling and radiochemical analysis methods to evaluate the DTM nuclides are limited by access to the material and potentially high personnel radiation exposure. In this case, theoretical calculation methods in combination with empirical methods based on remote radiation surveys need to be used to best advantage for determining the disposal inventory of DTM nuclides while minimizing exposure to radiation workers. Pursuant to this objective a standard for the theoretical evaluation of the radioactivity concentration of DTM nuclides in activated waste, is in process through ISO TC85/SC5 (ISO Technical Committee 85: Nuclear energy, nuclear technologies, and radiological protection; Subcommittee 5: Nuclear fuel cycle). The project team for this ISO standard was formed in 2011 and is composed of experts from 11 countries. The project team has been conducting technical discussions on theoretical methods for determining concentrations of radioactivity, and has developed the draft International Standard of ISO16966 'Theoretical activation calculation method to evaluate the radioactivity of activated waste generated at nuclear reactors' [2]. This paper describes the international standardization process developed by the ISO project team, and outlines the following two theoretical activity evaluation methods:? Point method? Range method. (authors)« less

Diagnosing and dealing with multicollinearity.

PubMed

Schroeder, M A

1990-04-01

The purpose of this article was to increase nurse researchers' awareness of the effects of collinear data in developing theoretical models for nursing practice. Collinear data distort the true value of the estimates generated from ordinary least-squares analysis. Theoretical models developed to provide the underpinnings of nursing practice need not be abandoned, however, because they fail to produce consistent estimates over repeated applications. It is also important to realize that multicollinearity is a data problem, not a problem associated with misspecification of a theorectical model. An investigator must first be aware of the problem, and then it is possible to develop an educated solution based on the degree of multicollinearity, theoretical considerations, and sources of error associated with alternative, biased, least-square regression techniques. Decisions based on theoretical and statistical considerations will further the development of theory-based nursing practice.

The Importance of Bonding to School for Healthy Development: Findings from the Social Development Research Group

ERIC Educational Resources Information Center

Catalano, Richard F.; Haggerty, Kevin P.; Oesterle, Sabrina; Fleming, Charles B.; Hawkins, J. David

2004-01-01

This paper summarizes investigations of school connectedness completed by the Social Development Research Group in two longitudinal studies, the Seattle Social Development Project and Raising Healthy Children. The theoretical importance of school connectedness, empirical support for the theoretical propositions of the impact of school…

Thermal Dissociation and Roaming Isomerization of Nitromethane: Experiment and Theory.

PubMed

Annesley, Christopher J; Randazzo, John B; Klippenstein, Stephen J; Harding, Lawrence B; Jasper, Ahren W; Georgievskii, Yuri; Ruscic, Branko; Tranter, Robert S

2015-07-16

The thermal decomposition of nitromethane provides a classic example of the competition between roaming mediated isomerization and simple bond fission. A recent theoretical analysis suggests that as the pressure is increased from 2 to 200 Torr the product distribution undergoes a sharp transition from roaming dominated to bond-fission dominated. Laser schlieren densitometry is used to explore the variation in the effect of roaming on the density gradients for CH3NO2 decomposition in a shock tube for pressures of 30, 60, and 120 Torr at temperatures ranging from 1200 to 1860 K. A complementary theoretical analysis provides a novel exploration of the effects of roaming on the thermal decomposition kinetics. The analysis focuses on the roaming dynamics in a reduced dimensional space consisting of the rigid-body motions of the CH3 and NO2 radicals. A high-level reduced-dimensionality potential energy surface is developed from fits to large-scale multireference ab initio calculations. Rigid body trajectory simulations coupled with master equation kinetics calculations provide high-level a priori predictions for the thermal branching between roaming and dissociation. A statistical model provides a qualitative/semiquantitative interpretation of the results. Modeling efforts explore the relation between the predicted roaming branching and the observed gradients. Overall, the experiments are found to be fairly consistent with the theoretically proposed branching ratio, but they are also consistent with a no-roaming scenario and the underlying reasons are discussed. The theoretical predictions are also compared with prior theoretical predictions, with a related statistical model, and with the extant experimental data for the decomposition of CH3NO2, and for the reaction of CH3 with NO2.

Neuroscience: viable applications in education?

PubMed

Devonshire, Ian M; Dommett, Eleanor J

2010-08-01

As a relatively young science, neuroscience is still finding its feet in potential collaborations with other disciplines. One such discipline is education, with the field of neuroeducation being on the horizon since the 1960s. However, although its achievements are now growing, the partnership has not been as successful as first hopes suggested it should be. Here the authors discuss the theoretical barriers and potential solutions to this, which have been suggested previously, with particular focus on levels of research in neuroscience and their applicability to education. Moreover, they propose that these theoretical barriers are driven and maintained by practical barriers surrounding common language and research literacy. They propose that by overcoming these practical barriers through appropriate training and shared experience, neuroeducation can reach its full potential.

Schwinger-variational-principle theory of collisions in the presence of multiple potentials

NASA Astrophysics Data System (ADS)

Robicheaux, F.; Giannakeas, P.; Greene, Chris H.

2015-08-01

A theoretical method for treating collisions in the presence of multiple potentials is developed by employing the Schwinger variational principle. The current treatment agrees with the local (regularized) frame transformation theory and extends its capabilities. Specifically, the Schwinger variational approach gives results without the divergences that need to be regularized in other methods. Furthermore, it provides a framework to identify the origin of these singularities and possibly improve the local frame transformation. We have used the method to obtain the scattering parameters for different confining potentials symmetric in x ,y . The method is also used to treat photodetachment processes in the presence of various confining potentials, thereby highlighting effects of the infinitely many closed channels. Two general features predicted are the vanishing of the total photoabsorption probability at every channel threshold and the occurrence of resonances below the channel thresholds for negative scattering lengths. In addition, the case of negative-ion photodetachment in the presence of uniform magnetic fields is also considered where unique features emerge at large scattering lengths.

Electromagnetic fields as structure-function zeitgebers in biological systems: environmental orchestrations of morphogenesis and consciousness.

PubMed

Rouleau, Nicolas; Dotta, Blake T

2014-01-01

Within a cell system structure dictates function. Any interaction between cells, or a cell and its environment, has the potential to have long term implications on the function of a given cell and emerging cell aggregates. The structure and function of cells are continuously subjected to modification by electrical and chemical stimuli. However, biological systems are also subjected to an ever-present influence: the electromagnetic (EM) environment. Biological systems have the potential to be influenced by subtle energies which are exchanged at atomic and subatomic scales as EM phenomena. These energy exchanges have the potential to manifest at higher orders of discourse and affect the output (behavior) of a biological system. Here we describe theoretical and experimental evidence of EM influence on cells and the integration of whole systems. Even weak interactions between EM energies and biological systems display the potential to affect a developing system. We suggest the growing literature of EM effects on biological systems has significant implications to the cell and its functional aggregates.

A comparison of SAR ATR performance with information theoretic predictions

NASA Astrophysics Data System (ADS)

Blacknell, David

2003-09-01

Performance assessment of automatic target detection and recognition algorithms for SAR systems (or indeed any other sensors) is essential if the military utility of the system / algorithm mix is to be quantified. This is a relatively straightforward task if extensive trials data from an existing system is used. However, a crucial requirement is to assess the potential performance of novel systems as a guide to procurement decisions. This task is no longer straightforward since a hypothetical system cannot provide experimental trials data. QinetiQ has previously developed a theoretical technique for classification algorithm performance assessment based on information theory. The purpose of the study presented here has been to validate this approach. To this end, experimental SAR imagery of targets has been collected using the QinetiQ Enhanced Surveillance Radar to allow algorithm performance assessments as a number of parameters are varied. In particular, performance comparisons can be made for (i) resolutions up to 0.1m, (ii) single channel versus polarimetric (iii) targets in the open versus targets in scrubland and (iv) use versus non-use of camouflage. The change in performance as these parameters are varied has been quantified from the experimental imagery whilst the information theoretic approach has been used to predict the expected variation of performance with parameter value. A comparison of these measured and predicted assessments has revealed the strengths and weaknesses of the theoretical technique as will be discussed in the paper.

Density functional theory and phytochemical study of Pistagremic acid

NASA Astrophysics Data System (ADS)

Ullah, Habib; Rauf, Abdur; Ullah, Zakir; Fazl-i-Sattar; Anwar, Muhammad; Shah, Anwar-ul-Haq Ali; Uddin, Ghias; Ayub, Khurshid

2014-01-01

We report here for the first time a comparative theoretical and experimental study of Pistagremic acid (P.A). We have developed a theoretical model for obtaining the electronic and spectroscopic properties of P.A. The simulated data showed nice correlation with the experimental data. The geometric and electronic properties were simulated at B3LYP/6-31 G (d, p) level of density functional theory (DFT). The optimized geometric parameters of P.A were found consistent with those from X-ray crystal structure. Differences of about 0.01 and 0.15 Å in bond length and 0.19-1.30° degree in the angles, respectively; were observed between the experimental and theoretical data. The theoretical vibrational bands of P.A were found to correlate with the experimental IR spectrum after a common scaling factor of 0.963. The experimental and predicted UV-Vis spectra (at B3LYP/6-31+G (d, p)) have 36 nm differences. This difference from experimental results is because of the condensed phase nature of P.A. Electronic properties such as Ionization Potential (I.P), Electron Affinities (E.A), co-efficient of highest occupied molecular orbital (HOMO), co-efficient of lowest unoccupied molecular orbital (LUMO) of P.A were estimated for the first time however, no correlation can be made with experiment. Inter-molecular interaction and its effect on vibrational (IR), electronic and geometric parameters were simulated by using Formic acid as model for hydrogen bonding in P.A.

Effect of random surface inhomogeneities on spectral properties of dielectric-disk microresonators: theory and modeling at millimeter wave range.

PubMed

Ganapolskii, E M; Eremenko, Z E; Tarasov, Yu V

2009-04-01

The influence of random axially homogeneous surface roughness on spectral properties of dielectric resonators of circular disk form is studied both theoretically and experimentally. To solve the equations governing the dynamics of electromagnetic fields, the method of eigenmode separation is applied previously developed with reference to inhomogeneous systems subject to arbitrary external static potential. We prove theoretically that it is the gradient mechanism of wave-surface scattering that is highly responsible for nondissipative loss in the resonator. The influence of side-boundary inhomogeneities on the resonator spectrum is shown to be described in terms of effective renormalization of mode wave numbers jointly with azimuth indices in the characteristic equation. To study experimentally the effect of inhomogeneities on the resonator spectrum, the method of modeling in the millimeter wave range is applied. As a model object, we use a dielectric disk resonator (DDR) fitted with external inhomogeneities randomly arranged at its side boundary. Experimental results show good agreement with theoretical predictions as regards the predominance of the gradient scattering mechanism. It is shown theoretically and confirmed in the experiment that TM oscillations in the DDR are less affected by surface inhomogeneities than TE oscillations with the same azimuth indices. The DDR model chosen for our study as well as characteristic equations obtained thereupon enable one to calculate both the eigenfrequencies and the Q factors of resonance spectral lines to fairly good accuracy. The results of calculations agree well with obtained experimental data.

'What women want': Using image theory to develop expectations of maternity care framework.

PubMed

Clark, Kim; Beatty, Shelley; Reibel, Tracy

2015-05-01

to develop, in consultation with women, a theoretically-grounded framework to guide the assessment of women's maternity-care experiences. qualitative research was undertaken with women to examine the appropriateness of Image Theory as a heuristic for understanding how women plan and evaluate their maternity-care experiences. maternity-care services in metropolitan and regional communities in Western Australia. an Episodes of Maternity Care Framework grounded in Image Theory was established that addressed various domains of women's perceptions and expectations of their maternity-care experience. previously-identified weaknesses of methods used to measure patient satisfaction were addressed and a valid framework for investigating women's perception of their maternity-services experiences was developed. This framework has the potential to contribute to the ongoing development and improvement of maternity-care service. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of an outcome measurement system for service planning for children and youth with special needs

PubMed Central

Kertoy, M K; Russell, D J; Rosenbaum, P; Jaffer, S; Law, M; McCauley, D; Gorter, J W

2013-01-01

Aim This study described the process used in developing an outcome measurement framework for system planning to improve services for children and youth with special needs and their families in a Canadian province. The study reports the results of several parent-completed measures, which would be useful in service planning as well as the acceptability and utility of these measures for use by families and service centres. Methods/results Development of a theoretical framework, consultation with key stakeholders, testing the utility of selected outcome measures and initial dissemination of results were critical elements in the successful development of an outcome system. Consultation with stakeholders confirmed use of the International Classification of Functioning, Disability and Health and the child-within-family-within community model as theoretical frameworks while building valuable partnerships and identifying potential barriers to implementation. Pilot testing showed three outcome measures were feasible for families to complete and the measures provided information about services for children that was valuable to families as well as service providers. Gaps in service delivery were identified and the need for better communication between service providers and communities to facilitate integrated services was highlighted. Conclusion The findings from this study can be used to implement an outcome measurement system for children with special needs and may serve as a resource for international researchers who are working to develop valid tools as well as outcome systems that are useful for system planning. PMID:22845889

Siblings of Youth with Autism Spectrum Disorders: Theoretical Perspectives on Sibling Relationships and Individual Adjustment.

PubMed

McHale, Susan M; Updegraff, Kimberly A; Feinberg, Mark E

2016-02-01

A burgeoning research literature investigates the sibling relationships of youth with autism spectrum disorder (ASD) and their implications for individual adjustment. Focusing on four relationship domains—behaviors,emotions, cognitions and involvement—and toward advancing this generally a theoretical literature, were view and apply tenets from a range of theoretical perspectives in an effort to illuminate the mechanisms underlying sibling relationship experiences and their adjustment implications. Our review suggests new directions for research to test theoretically-grounded hypotheses about how sibling relationships develop and are linked to individual adjustment. In addition, we consider how identifying underlying bio-psycho-social processes can aid in the development of interventions to promote warm and involved sibling relationships and positive youth development.

Design of all-optical, hot-electron current-direction-switching device based on geometrical asymmetry

PubMed Central

Kumarasinghe, Chathurangi S.; Premaratne, Malin; Gunapala, Sarath D.; Agrawal, Govind P.

2016-01-01

We propose a nano-scale current-direction-switching device(CDSD) that operates based on the novel phenomenon of geometrical asymmetry between two hot-electron generating plasmonic nanostructures. The proposed device is easy to fabricate and economical to develop compared to most other existing designs. It also has the ability to function without external wiring in nano or molecular circuitry since it is powered and controlled optically. We consider a such CDSD made of two dissimilar nanorods separated by a thin but finite potential barrier and theoretically derive the frequency-dependent electron/current flow rate. Our analysis takes in to account the quantum dynamics of electrons inside the nanorods under a periodic optical perturbation that are confined by nanorod boundaries, modelled as finite cylindrical potential wells. The influence of design parameters, such as geometric difference between the two nanorods, their volumes and the barrier width on quality parameters such as frequency-sensitivity of the current flow direction, magnitude of the current flow, positive to negative current ratio, and the energy conversion efficiency is discussed by considering a device made of Ag/TiO2/Ag. Theoretical insight and design guidelines presented here are useful for customizing our proposed CDSD for applications such as self-powered logic gates, power supplies, and sensors. PMID:26887286

Design of all-optical, hot-electron current-direction-switching device based on geometrical asymmetry.

PubMed

Kumarasinghe, Chathurangi S; Premaratne, Malin; Gunapala, Sarath D; Agrawal, Govind P

2016-02-18

We propose a nano-scale current-direction-switching device(CDSD) that operates based on the novel phenomenon of geometrical asymmetry between two hot-electron generating plasmonic nanostructures. The proposed device is easy to fabricate and economical to develop compared to most other existing designs. It also has the ability to function without external wiring in nano or molecular circuitry since it is powered and controlled optically. We consider a such CDSD made of two dissimilar nanorods separated by a thin but finite potential barrier and theoretically derive the frequency-dependent electron/current flow rate. Our analysis takes in to account the quantum dynamics of electrons inside the nanorods under a periodic optical perturbation that are confined by nanorod boundaries, modelled as finite cylindrical potential wells. The influence of design parameters, such as geometric difference between the two nanorods, their volumes and the barrier width on quality parameters such as frequency-sensitivity of the current flow direction, magnitude of the current flow, positive to negative current ratio, and the energy conversion efficiency is discussed by considering a device made of Ag/TiO2/Ag. Theoretical insight and design guidelines presented here are useful for customizing our proposed CDSD for applications such as self-powered logic gates, power supplies, and sensors.

Decentralised water systems: emotional influences on resource decision making.

PubMed

Mankad, Aditi

2012-09-01

The study of emotion has gathered momentum in the field of environmental science, specifically in the context of community resource decision-making. Of particular interest in this review is the potential influence of emotion, risk and threat perception on individuals' decisions to acceptance and adopt decentralised water systems, such as rainwater tanks and greywater systems. The role of message framing is also considered in detail, as well as the influences that different types of framing can have on decision making. These factors are considered as possible predictors for analysing community acceptance of decentralised water in urban environments. Concepts believed to be influenced by emotion, such as trust and framing, are also discussed as potentially meaningful contributors to an overall model of community acceptance of decentralised water. Recommendations are made for how emotion-based concepts, such as risk and threat, can be targeted to facilitate widespread adoption of decentralised systems and how researchers can explore different types of emotions that influence decision making in distinct ways. This review is an important theoretical step in advancing the psycho-social understanding of acceptance and adoption of on-site water sources. Avenues for future research are recommended, including the need for greater theoretical development to encourage future social science research on decentralised systems. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Theoretical Studies Applied to the Evaluation of the DFPase Bioremediation Potential against Chemical Warfare Agents Intoxication

PubMed Central

Soares, Flávia V.; de Castro, Alexandre A.; Pereira, Ander F.; Leal, Daniel H. S.; Mancini, Daiana T.; da Cunha, Elaine F. F.; Kuca, Kamil

2018-01-01

Organophosphorus compounds (OP) are part of a group of compounds that may be hazardous to health. They are called neurotoxic agents because of their action on the nervous system, inhibiting the acetylcholinesterase (AChE) enzyme and resulting in a cholinergic crisis. Their high toxicity and rapid action lead to irreversible damage to the nervous system, drawing attention to developing new treatment methods. The diisopropyl fluorophosphatase (DFPase) enzyme has been considered as a potent biocatalyst for the hydrolysis of toxic OP and has potential for bioremediation of this kind of intoxication. In order to investigate the degradation process of the nerve agents Tabun, Cyclosarin and Soman through the wild-type DFPase, and taking into account their stereochemistry, theoretical studies were carried out. The intermolecular interaction energy and other parameters obtained from the molecular docking calculations were used to construct a data matrix, which were posteriorly treated by statistical analyzes of chemometrics, using the PCA (Principal Components Analysis) multivariate analysis. The analyzed parameters seem to be quite important for the reaction mechanisms simulation (QM/MM). Our findings showed that the wild-type DFPase enzyme is stereoselective in hydrolysis, showing promising results for the catalytic degradation of the neurotoxic agents under study, with the degradation mechanism performed through two proposed pathways. PMID:29690585

Theoretical Studies Applied to the Evaluation of the DFPase Bioremediation Potential against Chemical Warfare Agents Intoxication.

PubMed

Soares, Flávia V; de Castro, Alexandre A; Pereira, Ander F; Leal, Daniel H S; Mancini, Daiana T; Krejcar, Ondrej; Ramalho, Teodorico C; da Cunha, Elaine F F; Kuca, Kamil

2018-04-23

Organophosphorus compounds (OP) are part of a group of compounds that may be hazardous to health. They are called neurotoxic agents because of their action on the nervous system, inhibiting the acetylcholinesterase (AChE) enzyme and resulting in a cholinergic crisis. Their high toxicity and rapid action lead to irreversible damage to the nervous system, drawing attention to developing new treatment methods. The diisopropyl fluorophosphatase (DFPase) enzyme has been considered as a potent biocatalyst for the hydrolysis of toxic OP and has potential for bioremediation of this kind of intoxication. In order to investigate the degradation process of the nerve agents Tabun, Cyclosarin and Soman through the wild-type DFPase, and taking into account their stereochemistry, theoretical studies were carried out. The intermolecular interaction energy and other parameters obtained from the molecular docking calculations were used to construct a data matrix, which were posteriorly treated by statistical analyzes of chemometrics, using the PCA (Principal Components Analysis) multivariate analysis. The analyzed parameters seem to be quite important for the reaction mechanisms simulation (QM/MM). Our findings showed that the wild-type DFPase enzyme is stereoselective in hydrolysis, showing promising results for the catalytic degradation of the neurotoxic agents under study, with the degradation mechanism performed through two proposed pathways.

Reducing social inequities in health through settings-related interventions -- a conceptual framework.

PubMed

Shareck, Martine; Frohlich, Katherine L; Poland, Blake

2013-06-01

The creation of supportive environments for health is a basic action principle of health promotion, and equity is a core value. A settings approach offers an opportunity to bridge these two, with its focus on the interplay between individual, environmental and social determinants of health. We conducted a scoping review of the literature on theoretical bases and practical applications of the settings approach. Interventions targeting social inequities in health through action on various settings were analyzed to establish what is done in health equity research and action as it relates to settings. Four elements emerged as central to an equity-focused settings approach: a focus on social determinants of health, addressing the needs of marginalized groups, effecting change in a setting's structure, and involving stakeholders. Each came with related challenges. To offer potential solutions to these challenges we developed a conceptual framework that integrates theoretical and methodological approaches, along with six core guiding principles, into a 'settings praxis'. Reducing social inequities in health through the creation of supportive environments requires the application of the settings approach in an innovative way. The proposed conceptual framework can serve as a guide to do so, and help develop, implement and evaluate equity-focused settings-related interventions.

Strengthening Theoretical Testing in Criminology Using Agent-based Modeling.

PubMed

Johnson, Shane D; Groff, Elizabeth R

2014-07-01

The Journal of Research in Crime and Delinquency ( JRCD ) has published important contributions to both criminological theory and associated empirical tests. In this article, we consider some of the challenges associated with traditional approaches to social science research, and discuss a complementary approach that is gaining popularity-agent-based computational modeling-that may offer new opportunities to strengthen theories of crime and develop insights into phenomena of interest. Two literature reviews are completed. The aim of the first is to identify those articles published in JRCD that have been the most influential and to classify the theoretical perspectives taken. The second is intended to identify those studies that have used an agent-based model (ABM) to examine criminological theories and to identify which theories have been explored. Ecological theories of crime pattern formation have received the most attention from researchers using ABMs, but many other criminological theories are amenable to testing using such methods. Traditional methods of theory development and testing suffer from a number of potential issues that a more systematic use of ABMs-not without its own issues-may help to overcome. ABMs should become another method in the criminologists toolbox to aid theory testing and falsification.

Theoretical and experimental study of mirrorless fiber optics refractometer based on quasi-Gaussian approach

NASA Astrophysics Data System (ADS)

Abdullah, M.; Krishnan, Ganesan; Saliman, Tiffany; Fakaruddin Sidi Ahmad, M.; Bidin, Noriah

2018-03-01

A mirrorless refractometer was studied and analyzed using the quasi-Gaussian beam approach. The Fresnel equation for reflectivity at the interface between two mediums with different refractive indices was used to calculate the directional reflectivity, R. Various liquid samples from 1.3325 to 1.4657 refractive indices units were used. Experimentally, a fiber bundle probe with a concentric configuration of 16 receiving fibers and a single transmitting fiber was employed to verify the developed models. The sensor performance in term of sensitivity, linear range, and resolution, were analyzed and calculated. It has been shown that the developed theoretical models are capable of providing quantitative guidance of the output of the sensor with high accuracy. The highest resolution of the sensor was 4.39  ×  10-3 refractive indices units, obtained by correlating the peak voltage along the refractive index. The resolution is sufficient for determining the specific refractive index increment of most polymer solutions, certain proteins, and also in monitoring bacterial growth. The accuracy, simplicity, and effectiveness of the proposed sensor over a long period of time while having non-contact measurements reflect a good potential for commercialization.

The future scalability of pH-based genome sequencers: A theoretical perspective

NASA Astrophysics Data System (ADS)

Go, Jonghyun; Alam, Muhammad A.

2013-10-01

Sequencing of human genome is an essential prerequisite for personalized medicine and early prognosis of various genetic diseases. The state-of-art, high-throughput genome sequencing technologies provide improved sequencing; however, their reliance on relatively expensive optical detection schemes has prevented wide-spread adoption of the technology in routine care. In contrast, the recently announced pH-based electronic genome sequencers achieve fast sequencing at low cost because of the compatibility with the current microelectronics technology. While the progress in technology development has been rapid, the physics of the sequencing chips and the potential for future scaling (and therefore, cost reduction) remain unexplored. In this article, we develop a theoretical framework and a scaling theory to explain the principle of operation of the pH-based sequencing chips and use the framework to explore various perceived scaling limits of the technology related to signal to noise ratio, well-to-well crosstalk, and sequencing accuracy. We also address several limitations inherent to the key steps of pH-based genome sequencers, which are widely shared by many other sequencing platforms in the market but remained unexplained properly so far.

Theoretical study of hull-rotor aerodynamic interference on semibuoyant vehicles

NASA Technical Reports Server (NTRS)

Spangler, S. B.; Smith, C. A.; Mendenhall, M. R.

1977-01-01

Theoretical methods are being developed to predict the mutual interference between rotor wakes and the hull for semibuoyant vehicles. The objective of the investigation is to predict the pressure distribution and overall loads on the hull in the presence of rotors whose locations, tilt angles, and disk loading are arbitrarily specified. The methods involve development of potential flow models for the hull alone in a nonuniform onset flow, a rotor wake which has the proper features to predict induced flow outside the wake, and a wake centerline specification technique which accounts for the reactions of the wake to a nonuniform crossflow. The flow models are used in sequence to solve for the mutual influence of the hull and rotor(s) on each other and the resulting loads. A flow separation model is included to estimate the influence of separation on hull loads at high sideslip angles. Only limited results have been obtained to date. These were obtained on a configuration which was tested in the Ames Research Center 7- by 10-Foot Low Speed Tunnel under Goodyear Aircraft Corporation sponsorship and indicate the nature of the interference pressure distribution on a configuration in hover.

ICT and OTs: a model of information and communication technology acceptance and utilisation by occupational therapists.

PubMed

Schaper, Louise K; Pervan, Graham P

2007-06-01

There is evidence to suggest that health professionals are reluctant to accept and utilise information and communication technologies (ICT) and concern is growing within health informatics research that this is contributing to the lag in adoption and utilisation of ICT across the health sector. Technology acceptance research within the field of information systems has been limited in its application to health and there is a concurrent need to develop and gain empirical support for models of technology acceptance within health and to examine acceptance and utilisation issues amongst health professionals to improve the success of information system implementation in this arena. This paper outlines a project that examines ICT acceptance and utilisation by Australian occupational therapists. It describes the theoretical basis behind the development of a research model and the methodology being employed to empirically validate the model using substantial quantitative, qualitative and longitudinal data. Preliminary results from Phase II of the study are presented. The theoretical significance of this work is that it uses a thoroughly constructed research model, with potentially the largest sample size ever tested, to extend technology acceptance research into the health sector.

An instrument to assess subjective task value beliefs regarding the decision to pursue postgraduate training.

PubMed

Hagemeier, Nicholas E; Murawski, Matthew M

2014-02-12

To develop and validate an instrument to assess subjective ratings of the perceived value of various postgraduate training paths followed using expectancy-value as a theoretical framework; and to explore differences in value beliefs across type of postgraduate training pursued and type of pharmacy training completed prior to postgraduate training. A survey instrument was developed to sample 4 theoretical domains of subjective task value: intrinsic value, attainment value, utility value, and perceived cost. Retrospective self-report methodology was employed to examine respondents' (N=1,148) subjective task value beliefs specific to their highest level of postgraduate training completed. Exploratory and confirmatory factor analytic techniques were used to evaluate and validate value belief constructs. Intrinsic, attainment, utility, cost, and financial value constructs resulted from exploratory factor analysis. Cross-validation resulted in a 26-item instrument that demonstrated good model fit. Differences in value beliefs were noted across type of postgraduate training pursued and pharmacy training characteristics. The Postgraduate Training Value Instrument demonstrated evidence of reliability and construct validity. The survey instrument can be used to assess value beliefs regarding multiple postgraduate training options in pharmacy and potentially inform targeted recruiting of individuals to those paths best matching their own value beliefs.

Verification of models for ballistic movement time and endpoint variability.

PubMed

Lin, Ray F; Drury, Colin G

2013-01-01

A hand control movement is composed of several ballistic movements. The time required in performing a ballistic movement and its endpoint variability are two important properties in developing movement models. The purpose of this study was to test potential models for predicting these two properties. Twelve participants conducted ballistic movements of specific amplitudes using a drawing tablet. The measured data of movement time and endpoint variability were then used to verify the models. This study was successful with Hoffmann and Gan's movement time model (Hoffmann, 1981; Gan and Hoffmann 1988) predicting more than 90.7% data variance for 84 individual measurements. A new theoretically developed ballistic movement variability model, proved to be better than Howarth, Beggs, and Bowden's (1971) model, predicting on average 84.8% of stopping-variable error and 88.3% of aiming-variable errors. These two validated models will help build solid theoretical movement models and evaluate input devices. This article provides better models for predicting end accuracy and movement time of ballistic movements that are desirable in rapid aiming tasks, such as keying in numbers on a smart phone. The models allow better design of aiming tasks, for example button sizes on mobile phones for different user populations.

Argumentation, critical thinking, nature of science and socioscientific issues: a dialogue between two researchers

NASA Astrophysics Data System (ADS)

Yacoubian, Hagop A.; Khishfe, Rola

2018-05-01

The purpose of this paper is to compare and contrast between two theoretical frameworks for addressing nature of science (NOS) and socioscientific issues (SSI) in school science. These frameworks are critical thinking (CT) and argumentation (AR). For the past years, the first and second authors of this paper have pursued research in this area using CT and AR as theoretical frameworks, respectively. Yacoubian argues that future citizens need to develop a critical mindset as they are guided to (1) practice making judgments on what views of NOS to acquire and (2) practice making decisions on SSI through applying their NOS understandings. Khishfe asserts that AR is an important component of decision making when dealing with SSI and the practice in AR in relation to controversial issues is needed for informed decision making. She argues that AR as a framework may assist in the development of more informed understandings of NOS. In this paper, the authors delve into a dialogue for (1) elucidating strengths and potential of each framework, (2) highlighting challenges that they face in their research using the frameworks in question, (3) exploring the extent to which the frameworks can overlap, and (4) proposing directions for future research.

Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces.

PubMed

Spezia, Riccardo; Martínez-Nuñez, Emilio; Vazquez, Saulo; Hase, William L

2017-04-28

In this Introduction, we show the basic problems of non-statistical and non-equilibrium phenomena related to the papers collected in this themed issue. Over the past few years, significant advances in both computing power and development of theories have allowed the study of larger systems, increasing the time length of simulations and improving the quality of potential energy surfaces. In particular, the possibility of using quantum chemistry to calculate energies and forces 'on the fly' has paved the way to directly study chemical reactions. This has provided a valuable tool to explore molecular mechanisms at given temperatures and energies and to see whether these reactive trajectories follow statistical laws and/or minimum energy pathways. This themed issue collects different aspects of the problem and gives an overview of recent works and developments in different contexts, from the gas phase to the condensed phase to excited states.This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'. © 2017 The Author(s).

[Everyday life and solidarity in north-east German rural communities - first qualitative results of the Rural Health Study].

PubMed

Nebelung, C; Forkel, J A; Elkeles, T

2010-03-01

There have been increasing discussions in the health sciences in recent years about socio-spatial influences on health activities. The starting point has been the growing territorial inequality in spatial development resources, which has an effect on the participatory chances of people in structurally weak regions. The concept of "peripherisation" is used to describe this change. Empirical investigations of socio-spatial resources at the local level are rare, because the theoretical preconditions have not been elaborated sufficiently for the theoretical modelling to be recognised for hypothesis-based empirical investigations. At the centre of this theorisation are analyses of the "social capital" of every-day actions. As part of the Rural Health Study 2008 at the University of Applied Science Neubrandenburg (involving a longitudinal analysis with quantitative surveys in 14 rural communities in north-eastern Germany 1973, 1994, 2008), a qualitative approach was also adopted with case and community studies. The first results are compared with the state of the literature. Case studies are presented showing strategies for adaptation and improvement of the individual's situation, and also the daily solidarity of people in villages. Development potentials are outlined. Georg Thieme Verlag KG Stuttgart. New York.

External Validity in the Study of Human Development: Theoretical and Methodological Issues

ERIC Educational Resources Information Center

Hultsch, David F.; Hickey, Tom

1978-01-01

An examination of the concept of external validity from two theoretical perspectives: a traditional mechanistic approach and a dialectical organismic approach. Examines the theoretical and methodological implications of these perspectives. (BD)

A theoretical method for the analysis and design of axisymmetric bodies. [flow distribution and incompressible fluids

NASA Technical Reports Server (NTRS)

Beatty, T. D.

1975-01-01

A theoretical method is presented for the computation of the flow field about an axisymmetric body operating in a viscous, incompressible fluid. A potential flow method was used to determine the inviscid flow field and to yield the boundary conditions for the boundary layer solutions. Boundary layer effects in the forces of displacement thickness and empirically modeled separation streamlines are accounted for in subsequent potential flow solutions. This procedure is repeated until the solutions converge. An empirical method was used to determine base drag allowing configuration drag to be computed.

Monolithic narrow-linewidth InGaAsP semiconductor laser for coherent optical communications

NASA Technical Reports Server (NTRS)

Palfrey, S. L.; Enstrom, R. E.; Longeway, P. A.

1989-01-01

A design for a monolithic narrow-linewidth InGaAsP diode laser has been developed using a multiple-quantum-well (MQW) extended-passive-cavity distributed-Bragg-reflector (DBR) laser design. Theoretical results indicate that this structure has the potential for a linewidth of 100 kHz or less. To realize this device, a number of the fabrication techniques required to integrate low-loss passive waveguides with active regions have been developed using a DBR laser structure. In addition, the MOCVD growth of InGaAs MQW laser structures has been developed, and threshold current densities as low as 1.6 kA/sq cm have been obtained from broad-stripe InGaAs/InGaAsP separate-confinement-heterostructure MQW lasers.

How do social norms influence prosocial development?

PubMed

House, Bailey R

2018-04-01

Humans are both highly prosocial and extremely sensitive to social norms, and some theories suggest that norms are necessary to account for uniquely human forms of prosocial behavior and cooperation. Understanding how norms influence prosocial behavior is thus essential if we are to describe the psychology and development of prosocial behavior. In this article I review recent research from across the social sciences that provides (1) a theoretical model of how norms influence prosocial behavior, (2) empirical support for the model based on studies with adults and children, and (3) predictions about the psychological mechanisms through which norms shape prosocial behavior. I conclude by discussing the need for future studies into how prosocial behavior develops through emerging interactions between culturally varying norms, social cognition, emotions, and potentially genes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Developing parenting programs to prevent child health risk behaviors: a practice model

PubMed Central

Jackson, Christine; Dickinson, Denise M.

2009-01-01

Research indicates that developing public health programs to modify parenting behaviors could lead to multiple beneficial health outcomes for children. Developing feasible effective parenting programs requires an approach that applies a theory-based model of parenting to a specific domain of child health and engages participant representatives in intervention development. This article describes this approach to intervention development in detail. Our presentation emphasizes three points that provide key insights into the goals and procedures of parenting program development. These are a generalized theoretical model of parenting derived from the child development literature, an established eight-step parenting intervention development process and an approach to integrating experiential learning methods into interventions for parents and children. By disseminating this framework for a systematic theory-based approach to developing parenting programs, we aim to support the program development efforts of public health researchers and practitioners who recognize the potential of parenting programs to achieve primary prevention of health risk behaviors in children. PMID:19661165

Theoretical Analysis of Canadian Lifelong Education Development

ERIC Educational Resources Information Center

Mukan, Natalia; Barabash, Olena; Busko, Maria

2014-01-01

In the article, the problem of Canadian lifelong education development has been studied. The main objectives of the article are defined as theoretical analysis of scientific and pedagogical literature which highlights different aspects of the research problem; periods of lifelong education development; and determination of lifelong learning role…

Theoretical Bridge-Building: The Career Development Project for the 21st Century Meets the New Era of Human Resource Development

ERIC Educational Resources Information Center

Cameron, Roslyn

2009-01-01

There are theoretical and disciplinary field links between career development and human resource development, however interdisciplinary dialogue between the two fields has been essentially limited to one-way dialogue. This one-way dialogue occurs from within the human resource development field, due to the explicit inclusion of career development…

Potential for polyhydroxyalkanoate production on German or European municipal waste water treatment plants.

PubMed

Pittmann, T; Steinmetz, H

2016-08-01

Biopolymers, which are made of renewable raw materials and/or biodegradable residual materials present a possible alternative to common plastic. A potential analysis, based on experimental results in laboratory scale and detailed data from German waste water treatment plants, showed that the theoretically possible production of biopolymers in Germany amounts to more than 20% of the 2015 worldwide biopolymer production. In addition a profound estimation regarding all European Union member states showed that theoretically about 115% of the actual worldwide biopolymer production could be produced on European waste water treatment plants. With an upgraded biopolymer production and a theoretically reachable biopolymer proportion of around 60% of the cell dry weight a total of 1,794,656tPHAa or approximately 236% of today's biopolymer production could be produced on waste water treatment plants in the European Union, using primary sludge as raw material only. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optical spectra and band structure of Ag(x)Ga(x)Ge(1-x)Se2 (x = 0.333, 0.250, 0.200, 0.167) single crystals: experiment and theory.

PubMed

Reshak, A H; Parasyuk, O V; Fedorchuk, A O; Kamarudin, H; Auluck, S; Chyský, J

2013-12-05

Theoretical and experimental studies of the Ag(x)Ga(x)Ge(1-x)Se2 (x = 0.333, 0.250, 0.200, 0.167) single crystals are performed. These crystals possess a lot of intrinsic defects which are responsible for their optoelectronic features. The theoretical investigations were performed by means of DFT calculations using different exchange-correlation potentials. The experimental studies were carried out using the modulated VUV ellipsometry for dielectric constants and birefringence studies. The comparison of the structure obtained from X-ray with the theoretically optimized structure is presented. The crucial role of the intrinsic defect states is manifested in the choice of the exchange correlation potential used. The data may be applicable for a large number of the ternary chalcogenides which are sensitive to the presence of the local disordered states near the band edges.

The picture exchange communication system.

PubMed

Bondy, A S; Frost, L A

1998-01-01

The Picture Exchange Communication System (PECS) was developed as a means to teach children with autism and related developmental disabilities a rapidly acquired, self-initiating, functional communication system. Its theoretical roots combine principles from applied behavior analysis and guidelines established within the field of alternative and augmentative communication. This approach has several potential advantages relative to imitation-based strategies (both vocal and gestural) and symbol selection strategies. The system begins with the exchange of simple icons but rapidly builds "sentence" structure. The system also emphasizes developing the request function prior to developing responding to simple questions and commenting. The development of requesting with a sentence structure also permits the rapid development of attributes more traditionally taught within a receptive mode. The relationship between the introduction of PECS and various other behavioral issues (i.e., social approach and behavior management) as well as its relationship to the codevelopment of speech are reviewed.