Science.gov

Sample records for accepted theoretical model

  1. Understanding intention to use electronic information resources: A theoretical extension of the technology acceptance model (TAM).

    PubMed

    Tao, Donghua

    2008-11-06

    This study extended the Technology Acceptance Model (TAM) by examining the roles of two aspects of e-resource characteristics, namely, information quality and system quality, in predicting public health students' intention to use e-resources for completing research paper assignments. Both focus groups and a questionnaire were used to collect data. Descriptive analysis, data screening, and Structural Equation Modeling (SEM) techniques were used for data analysis. The study found that perceived usefulness played a major role in determining students' intention to use e-resources. Perceived usefulness and perceived ease of use fully mediated the impact that information quality and system quality had on behavior intention. The research model enriches the existing technology acceptance literature by extending TAM. Representing two aspects of e-resource characteristics provides greater explanatory information for diagnosing problems of system design, development, and implementation.

  2. Empirical Testing of a Theoretical Extension of the Technology Acceptance Model: An Exploratory Study of Educational Wikis

    ERIC Educational Resources Information Center

    Liu, Xun

    2010-01-01

    This study extended the technology acceptance model and empirically tested the new model with wikis, a new type of educational technology. Based on social cognitive theory and the theory of planned behavior, three new variables, wiki self-efficacy, online posting anxiety, and perceived behavioral control, were added to the original technology…

  3. Extending the Technology Acceptance Model: Policy Acceptance Model (PAM)

    NASA Astrophysics Data System (ADS)

    Pierce, Tamra

    There has been extensive research on how new ideas and technologies are accepted in society. This has resulted in the creation of many models that are used to discover and assess the contributing factors. The Technology Acceptance Model (TAM) is one that is a widely accepted model. This model examines people's acceptance of new technologies based on variables that directly correlate to how the end user views the product. This paper introduces the Policy Acceptance Model (PAM), an expansion of TAM, which is designed for the analysis and evaluation of acceptance of new policy implementation. PAM includes the traditional constructs of TAM and adds the variables of age, ethnicity, and family. The model is demonstrated using a survey of people's attitude toward the upcoming healthcare reform in the United States (US) from 72 survey respondents. The aim is that the theory behind this model can be used as a framework that will be applicable to studies looking at the introduction of any new or modified policies.

  4. Introduction to Theoretical Modelling

    NASA Astrophysics Data System (ADS)

    Davis, Matthew J.; Gardiner, Simon A.; Hanna, Thomas M.; Nygaard, Nicolai; Proukakis, Nick P.; Szymańska, Marzena H.

    2013-02-01

    We briefly overview commonly encountered theoretical notions arising in the modelling of quantum gases, intended to provide a unified background to the `language' and diverse theoretical models presented elsewhere in this book, and aimed particularly at researchers from outside the quantum gases community.

  5. Predicting Innovation Acceptance by Simulation in Virtual Environments (Theoretical Foundations)

    NASA Astrophysics Data System (ADS)

    León, Noel; Duran, Roberto; Aguayo, Humberto; Flores, Myrna

    This paper extends the current development of a methodology for Computer Aided Innovation. It begins with a presentation of concepts related to the perceived capabilities of virtual environments in the Innovation Cycle. The main premise establishes that it is possible to predict the acceptance of a new product in a specific market, by releasing an early prototype in a virtual scenario to quantify its general reception and to receive early feedback from potential customers. The paper continues to focus this research on a synergistic extension of techniques that have their origins in optimization and innovation disciplines. TRIZ (Theory of Inventive Problem Solving), extends the generation of variants with Evolutionary Algorithms (EA) and finally to present the designer and the intended customer, creative and innovative alternatives. All of this developed on a virtual software interface (Virtual World). The work continues with a general description of the project as a step forward to improve the overall strategy.

  6. Modeling Patients' Acceptance of Provider-delivered E-health

    PubMed Central

    Wilson, E. Vance; Lankton, Nancy K.

    2004-01-01

    Objective: Health care providers are beginning to deliver a range of Internet-based services to patients; however, it is not clear which of these e-health services patients need or desire. The authors propose that patients' acceptance of provider-delivered e-health can be modeled in advance of application development by measuring the effects of several key antecedents to e-health use and applying models of acceptance developed in the information technology (IT) field. Design: This study tested three theoretical models of IT acceptance among patients who had recently registered for access to provider-delivered e-health. Measurements: An online questionnaire administered items measuring perceptual constructs from the IT acceptance models (intrinsic motivation, perceived ease of use, perceived usefulness/extrinsic motivation, and behavioral intention to use e-health) and five hypothesized antecedents (satisfaction with medical care, health care knowledge, Internet dependence, information-seeking preference, and health care need). Responses were collected and stored in a central database. Results: All tested IT acceptance models performed well in predicting patients' behavioral intention to use e-health. Antecedent factors of satisfaction with provider, information-seeking preference, and Internet dependence uniquely predicted constructs in the models. Conclusion: Information technology acceptance models provide a means to understand which aspects of e-health are valued by patients and how this may affect future use. In addition, antecedents to the models can be used to predict e-health acceptance in advance of system development. PMID:15064290

  7. Integrated Model for E-Learning Acceptance

    NASA Astrophysics Data System (ADS)

    Ramadiani; Rodziah, A.; Hasan, S. M.; Rusli, A.; Noraini, C.

    2016-01-01

    E-learning is not going to work if the system is not used in accordance with user needs. User Interface is very important to encourage using the application. Many theories had discuss about user interface usability evaluation and technology acceptance separately, actually why we do not make it correlation between interface usability evaluation and user acceptance to enhance e-learning process. Therefore, the evaluation model for e-learning interface acceptance is considered important to investigate. The aim of this study is to propose the integrated e-learning user interface acceptance evaluation model. This model was combined some theories of e-learning interface measurement such as, user learning style, usability evaluation, and the user benefit. We formulated in constructive questionnaires which were shared at 125 English Language School (ELS) students. This research statistics used Structural Equation Model using LISREL v8.80 and MANOVA analysis.

  8. Model of aircraft passenger acceptance

    NASA Technical Reports Server (NTRS)

    Jacobson, I. D.

    1978-01-01

    A technique developed to evaluate the passenger response to a transportation system environment is described. Reactions to motion, noise, temperature, seating, ventilation, sudden jolts and descents are modeled. Statistics are presented for the age, sex, occupation, and income distributions of the candidates analyzed. Values are noted for the relative importance of system variables such as time savings, on-time arrival, convenience, comfort, safety, the ability to read and write, and onboard services.

  9. Theoretical models for supernovae

    SciTech Connect

    Woosley, S.E.; Weaver, T.A.

    1981-09-21

    The results of recent numerical simulations of supernova explosions are presented and a variety of topics discussed. Particular emphasis is given to (i) the nucleosynthesis expected from intermediate mass (10sub solar less than or equal to M less than or equal to 100 Msub solar) Type II supernovae and detonating white dwarf models for Type I supernovae, (ii) a realistic estimate of the ..gamma..-line fluxes expected from this nucleosynthesis, (iii) the continued evolution, in one and two dimensions, of intermediate mass stars wherein iron core collapse does not lead to a strong, mass-ejecting shock wave, and (iv) the evolution and explosion of vary massive stars (M greater than or equal to 100 Msub solar of both Population I and III. In one dimension, nuclear burning following a failed core bounce does not appear likely to lead to a supernova explosion although, in two dimensions, a combination of rotation and nuclear burning may do so. Near solar proportions of elements from neon to calcium and very brilliant optical displays may be created by hypernovae, the explosions of stars in the mass range 100 M/sub solar/ to 300 M/sub solar/. Above approx. 300 M/sub solar/ a black hole is created by stellar collapse following carbon ignition. Still more massive stars may be copious producers of /sup 4/He and /sup 14/N prior to their collapse on the pair instability.

  10. Do I Have to Learn Something New? Mental Models and the Acceptance of Replacement Technologies

    ERIC Educational Resources Information Center

    Zhang, Wei; Xu, Peng

    2011-01-01

    Few studies in technology acceptance have explicitly addressed the acceptance of replacement technologies, technologies that replace legacy ones that have been in use. This article explores this issue through the theoretical lens of mental models. We contend that accepting replacement technologies entails both mental model maintenance and mental…

  11. Modeling Computer Usage Intentions of Tertiary Students in a Developing Country through the Technology Acceptance Model

    ERIC Educational Resources Information Center

    Afari-Kumah, Eben; Achampong, Akwasi Kyere

    2010-01-01

    This study aims to examine the computer usage intentions of Ghanaian Tertiary Students. The Technology Acceptance Model was adopted as the theoretical framework to ascertain whether it could help explain behavioral intentions of individuals to accept and use technology. Factor analysis was used to assess the construct validity of the initial…

  12. Theoretical Models of Spintronic Materials

    NASA Astrophysics Data System (ADS)

    Damewood, Liam James

    In the past three decades, spintronic devices have played an important technological role. Half-metallic alloys have drawn much attention due to their special properties and promised spintronic applications. This dissertation describes some theoretical techniques used in first-principal calculations of alloys that may be useful for spintronic device applications with an emphasis on half-metallic ferromagnets. I consider three types of simple spintronic materials using a wide range of theoretical techniques. They are (a) transition metal based half-Heusler alloys, like CrMnSb, where the ordering of the two transition metal elements within the unit cell can cause the material to be ferromagnetic semiconductors or semiconductors with zero net magnetic moment, (b) half-Heusler alloys involving Li, like LiMnSi, where the Li stabilizes the structure and increases the magnetic moment of zinc blende half-metals by one Bohr magneton per formula unit, and (c) zinc blende alloys, like CrAs, where many-body techniques improve the fundamental gap by considering the physical effects of the local field. Also, I provide a survey of the theoretical models and numerical methods used to treat the above systems.

  13. M-theoretic matrix models

    NASA Astrophysics Data System (ADS)

    Grassi, Alba; Mariño, Marcos

    2015-02-01

    Some matrix models admit, on top of the usual 't Hooft expansion, an M-theory-like expansion, i.e. an expansion at large N but where the rest of the parameters are fixed, instead of scaling with N . These models, which we call M-theoretic matrix models, appear in the localization of Chern-Simons-matter theories, and also in two-dimensional statistical physics. Generically, their partition function receives non-perturbative corrections which are not captured by the 't Hooft expansion. In this paper, we discuss general aspects of these type of matrix integrals and we analyze in detail two different examples. The first one is the matrix model computing the partition function of supersymmetric Yang-Mills theory in three dimensions with one adjoint hypermultiplet and N f fundamentals, which has a conjectured M-theory dual, and which we call the N f matrix model. The second one, which we call the polymer matrix model, computes form factors of the 2d Ising model and is related to the physics of 2d polymers. In both cases we determine their exact planar limit. In the N f matrix model, the planar free energy reproduces the expected behavior of the M-theory dual. We also study their M-theory expansion by using Fermi gas techniques, and we find non-perturbative corrections to the 't Hooft expansion.

  14. Theoretical Models of Astrochemical Processes

    NASA Technical Reports Server (NTRS)

    Charnley, Steven

    2009-01-01

    Interstellar chemistry provides a natural laboratory for studying exotic species and processes at densities, temperatures, and reaction rates. that are difficult or impractical to address in the laboratory. Thus, many chemical reactions considered too sloe by the standards of terrestrial chemistry, can be 'observed and modeled. Curious proposals concerning the nature and chemistry of complex interstellar organic molecules will be described. Catalytic reactions on "rain surfaces can, in principle, lead to a lame variety of species and this has motivated many laboratory and theoretical studies. Gas phase processes may also build lame species in molecular clouds. Future laboratory data and computational tools needed to construct accurate chemical models of various astronomical sources to be observed by Herschel and ALMA will be outlined.

  15. Chinese Nurses' Acceptance of PDA: A Cross-Sectional Survey Using a Technology Acceptance Model.

    PubMed

    Wang, Yanling; Xiao, Qian; Sun, Liu; Wu, Ying

    2016-01-01

    This study explores Chinese nurses' acceptance of PDA, using a questionnaire based on the framework of Technology Acceptance Model (TAM). 357 nurses were involved in the study. The results reveal the scores of the nurses' acceptance of PDA were means 3.18~3.36 in four dimensions. The younger of nurses, the higher nurses' title, the longer previous usage time, the more experienced using PDA, and the more acceptance of PDA. Therefore, the hospital administrators may change strategies to enhance nurses' acceptance of PDA, and promote the wide application of PDA.

  16. Measuring Technology Acceptance Level of Turkish Pre-Service English Teachers by Using Technology Acceptance Model

    ERIC Educational Resources Information Center

    Kirmizi, Özkan

    2014-01-01

    The aim of this study is to investigate technology acceptance of prospective English teachers by using Technology Acceptance Model (TAM) in Turkish context. The study is based on Structural Equation Model (SEM). The participants of the study from English Language Teaching Departments of Hacettepe, Gazi and Baskent Universities. The participants…

  17. Technology, Demographic Characteristics and E-Learning Acceptance: A Conceptual Model Based on Extended Technology Acceptance Model

    ERIC Educational Resources Information Center

    Tarhini, Ali; Elyas, Tariq; Akour, Mohammad Ali; Al-Salti, Zahran

    2016-01-01

    The main aim of this paper is to develop an amalgamated conceptual model of technology acceptance that explains how individual, social, cultural and organizational factors affect the students' acceptance and usage behaviour of the Web-based learning systems. More specifically, the proposed model extends the Technology Acceptance Model (TAM) to…

  18. Parameters and error of a theoretical model

    SciTech Connect

    Moeller, P.; Nix, J.R.; Swiatecki, W.

    1986-09-01

    We propose a definition for the error of a theoretical model of the type whose parameters are determined from adjustment to experimental data. By applying a standard statistical method, the maximum-likelihoodlmethod, we derive expressions for both the parameters of the theoretical model and its error. We investigate the derived equations by solving them for simulated experimental and theoretical quantities generated by use of random number generators. 2 refs., 4 tabs.

  19. Technological Diffusion within Educational Institutions: Applying the Technology Acceptance Model.

    ERIC Educational Resources Information Center

    Wolski, Stacy; Jackson, Sally

    Expectancy models of behavior such as the Theory of Reasoned Action (TRA) and the Technology Acceptance Model (TAM) offer guidelines that aid efforts to facilitate use of new technology. These models remind us that both acceptance of and resistance to technology use are grounded in beliefs and norms regarding the technology. Although TAM is widely…

  20. Gerontechnology acceptance by elderly Hong Kong Chinese: a senior technology acceptance model (STAM).

    PubMed

    Chen, Ke; Chan, Alan Hoi Shou

    2014-01-01

    The purpose of this study was to develop and test a senior technology acceptance model (STAM) aimed at understanding the acceptance of gerontechnology by older Hong Kong Chinese people. The proposed STAM extended previous technology acceptance models and theories by adding age-related health and ability characteristics of older people. The proposed STAM was empirically tested using a cross-sectional questionnaire survey with a sample of 1012 seniors aged 55 and over in Hong Kong. The result showed that STAM was strongly supported and could explain 68% of the variance in the use of gerontechnology. For older Hong Kong Chinese, individual attributes, which include age, gender, education, gerontechnology self-efficacy and anxiety, and health and ability characteristics, as well as facilitating conditions explicitly and directly affected technology acceptance. These were better predictors of gerontechnology usage behaviour (UB) than the conventionally used attitudinal factors (usefulness and ease of use).

  1. Evaluation of the Acceptance of Audience Response System by Corporations Using the Technology Acceptance Model

    NASA Astrophysics Data System (ADS)

    Chu, Hsing-Hui; Lu, Ta-Jung; Wann, Jong-Wen

    The purpose of this research is to explore enterprises' acceptance of Audience Response System (ARS) using Technology Acceptance Model (TAM). The findings show that (1) IT characteristics and facilitating conditions could be external variables of TAM. (2) The degree of E-business has positive significant correlation with behavioral intention of employees. (3) TAM is a good model to predict and explain IT acceptance. (4) Demographic variables, industry and firm characteristics have no significant correlation with ARS acceptance. The results provide useful information to managers and ARS providers that (1) ARS providers should focus more on creating different usages to enhance interactivity and employees' using intention. (2) Managers should pay attention to build sound internal facilitating conditions for introducing IT. (3) According to the degree of E-business, managers should set up strategic stages of introducing IT. (4) Providers should increase product promotion and also leverage academic and government to promote ARS.

  2. APPRENTICESHIP--A THEORETICAL MODEL.

    ERIC Educational Resources Information Center

    DUFTY, NORMAN F.

    AN INQUIRY INTO RECRUITMENT OF APPRENTICES TO SKILLED TRADES IN WESTERN AUSTRALIA INDICATED LITTLE CORRELATION BETWEEN THE NUMBER OF NEW APPRENTICES AND THE LEVEL OF INDUSTRIAL EMPLOYMENT OR THE TOTAL NUMBER OF APPRENTICES. THIS ARTICLE ATTEMPTS TO OUTLINE A MATHEMATICAL MODEL OF AN APPRENTICESHIP SYSTEM AND DISCUSS ITS IMPLICATIONS. THE MODEL, A…

  3. Theoretical Modelling of Hot Stars

    NASA Astrophysics Data System (ADS)

    Najarro, F.; Hillier, D. J.; Figer, D. F.; Geballe, T. R.

    1999-06-01

    Recent progress towards model atmospheres for hot stars is discussed. A new generation of NLTE wind blanketed models, together with high S/N spectra of the hot star population in the central parsec, which are currently being obtained, will allow metal abundance determinations (Fe, Si, Mg, Na, etc). Metallicity studies of hot stars in the IR will provide major constraints not only on the theory of evolution of massive stars but also on our efforts to solve the puzzle of the central parsecs of the Galaxy. Preliminary results suggest that the metallicity of the Pistol Star is 3 times solar, thus indicating strong chemical enrichment of the gas in the Galactic Center.

  4. Theoretical Modeling of Interstellar Chemistry

    NASA Technical Reports Server (NTRS)

    Charnley, Steven

    2009-01-01

    The chemistry of complex interstellar organic molecules will be described. Gas phase processes that may build large carbon-chain species in cold molecular clouds will be summarized. Catalytic reactions on grain surfaces can lead to a large variety of organic species, and models of molecule formation by atom additions to multiply-bonded molecules will be presented. The subsequent desorption of these mixed molecular ices can initiate a distinctive organic chemistry in hot molecular cores. The general ion-molecule pathways leading to even larger organics will be outlined. The predictions of this theory will be compared with observations to show how possible organic formation pathways in the interstellar medium may be constrained. In particular, the success of the theory in explaining trends in the known interstellar organics, in predicting recently-detected interstellar molecules, and, just as importantly, non-detections, will be discussed.

  5. Theoretical models of helicopter rotor noise

    NASA Technical Reports Server (NTRS)

    Hawkings, D. L.

    1978-01-01

    For low speed rotors, it is shown that unsteady load models are only partially successful in predicting experimental levels. A theoretical model is presented which leads to the concept of unsteady thickness noise. This gives better agreement with test results. For high speed rotors, it is argued that present models are incomplete and that other mechanisms are at work. Some possibilities are briefly discussed.

  6. Examining Engineering & Technology Students' Acceptance of Network Virtualization Technology Using the Technology Acceptance Model

    ERIC Educational Resources Information Center

    Yousif, Wael K.

    2010-01-01

    This causal and correlational study was designed to extend the Technology Acceptance Model (TAM) and to test its applicability to Valencia Community College (VCC) Engineering and Technology students as the target user group when investigating the factors influencing their decision to adopt and to utilize VMware as the target technology. In…

  7. User Acceptance of Long-Term Evolution (LTE) Services: An Application of Extended Technology Acceptance Model

    ERIC Educational Resources Information Center

    Park, Eunil; Kim, Ki Joon

    2013-01-01

    Purpose: The aim of this paper is to propose an integrated path model in order to explore user acceptance of long-term evolution (LTE) services by examining potential causal relationships between key psychological factors and user intention to use the services. Design/methodology/approach: Online survey data collected from 1,344 users are analysed…

  8. User Acceptance of YouTube for Procedural Learning: An Extension of the Technology Acceptance Model

    ERIC Educational Resources Information Center

    Lee, Doo Young; Lehto, Mark R.

    2013-01-01

    The present study was framed using the Technology Acceptance Model (TAM) to identify determinants affecting behavioral intention to use YouTube. Most importantly, this research emphasizes the motives for using YouTube, which is notable given its extrinsic task goal of being used for procedural learning tasks. Our conceptual framework included two…

  9. 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.

  10. Theoretical Models and Processes of Reading.

    ERIC Educational Resources Information Center

    Singer, Harry, Ed.; Ruddell, Robert B., Ed.

    The first section of this two-part collection of articles contains six papers and their discussions read at a symposium on Theoretical Models and Processes of Reading. The papers cover the linguistic, perceptual, and cognitive components involved in reading. The models attempt to integrate the variables that influence the perception, recognition,…

  11. A Theoretical Model of Intrapersonal Agenda.

    ERIC Educational Resources Information Center

    Yang, Jian

    Prior research has shown that the media play an agenda-setting role in political campaigns. A theoretical model was developed to investigate intrapersonal agenda's relationship with certain contingent factors. To test the model a study of the intrapersonal agenda (personally perceived salience of public issues) was then conducted as part of the…

  12. Investigating Students' Acceptance and Self-Efficacy of E-Learning at Al-Aqsa University Based on TAM Model

    ERIC Educational Resources Information Center

    Mahdi, Hasan Rebhi

    2014-01-01

    The study aimed at investigating the influence of E-learning Self-Efficacy (ELSE) on the acceptance of e-learning by using the Technology Acceptance Model (TAM). According to the TAM which used as the theoretical basis, both of the Perceived Usefulness (PU) and the Perceived Ease of Use (PEOU) influence directly the end user's Behavioral Intention…

  13. Hybrid quantum teleportation: A theoretical model

    SciTech Connect

    Takeda, Shuntaro; Mizuta, Takahiro; Fuwa, Maria; Yoshikawa, Jun-ichi; Yonezawa, Hidehiro; Furusawa, Akira

    2014-12-04

    Hybrid quantum teleportation – continuous-variable teleportation of qubits – is a promising approach for deterministically teleporting photonic qubits. We propose how to implement it with current technology. Our theoretical model shows that faithful qubit transfer can be achieved for this teleportation by choosing an optimal gain for the teleporter’s classical channel.

  14. Hybrid quantum teleportation: A theoretical model

    NASA Astrophysics Data System (ADS)

    Takeda, Shuntaro; Mizuta, Takahiro; Fuwa, Maria; Yoshikawa, Jun-ichi; Yonezawa, Hidehiro; Furusawa, Akira

    2014-12-01

    Hybrid quantum teleportation - continuous-variable teleportation of qubits - is a promising approach for deterministically teleporting photonic qubits. We propose how to implement it with current technology. Our theoretical model shows that faithful qubit transfer can be achieved for this teleportation by choosing an optimal gain for the teleporter's classical channel.

  15. Theoretical Modeling for Hepatic Microwave Ablation

    PubMed Central

    Prakash, Punit

    2010-01-01

    Thermal tissue ablation is an interventional procedure increasingly being used for treatment of diverse medical conditions. Microwave ablation is emerging as an attractive modality for thermal therapy of large soft tissue targets in short periods of time, making it particularly suitable for ablation of hepatic and other tumors. Theoretical models of the ablation process are a powerful tool for predicting the temperature profile in tissue and resultant tissue damage created by ablation devices. These models play an important role in the design and optimization of devices for microwave tissue ablation. Furthermore, they are a useful tool for exploring and planning treatment delivery strategies. This review describes the status of theoretical models developed for microwave tissue ablation. It also reviews current challenges, research trends and progress towards development of accurate models for high temperature microwave tissue ablation. PMID:20309393

  16. THE TECHNOLOGY ACCEPTANCE MODEL: ITS PAST AND ITS FUTURE IN HEALTH CARE

    PubMed Central

    HOLDEN, RICHARD J.; KARSH, BEN-TZION

    2009-01-01

    Increasing interest in end users’ reactions to health information technology (IT) has elevated the importance of theories that predict and explain health IT acceptance and use. This paper reviews the application of one such theory, the Technology Acceptance Model (TAM), to health care. We reviewed 16 data sets analyzed in over 20 studies of clinicians using health IT for patient care. Studies differed greatly in samples and settings, health ITs studied, research models, relationships tested, and construct operationalization. Certain TAM relationships were consistently found to be significant, whereas others were inconsistent. Several key relationships were infrequently assessed. Findings show that TAM predicts a substantial portion of the use or acceptance of health IT, but that the theory may benefit from several additions and modifications. Aside from improved study quality, standardization, and theoretically motivated additions to the model, an important future direction for TAM is to adapt the model specifically to the health care context, using beliefs elicitation methods. PMID:19615467

  17. The technology acceptance model: its past and its future in health care.

    PubMed

    Holden, Richard J; Karsh, Ben-Tzion

    2010-02-01

    Increasing interest in end users' reactions to health information technology (IT) has elevated the importance of theories that predict and explain health IT acceptance and use. This paper reviews the application of one such theory, the Technology Acceptance Model (TAM), to health care. We reviewed 16 data sets analyzed in over 20 studies of clinicians using health IT for patient care. Studies differed greatly in samples and settings, health ITs studied, research models, relationships tested, and construct operationalization. Certain TAM relationships were consistently found to be significant, whereas others were inconsistent. Several key relationships were infrequently assessed. Findings show that TAM predicts a substantial portion of the use or acceptance of health IT, but that the theory may benefit from several additions and modifications. Aside from improved study quality, standardization, and theoretically motivated additions to the model, an important future direction for TAM is to adapt the model specifically to the health care context, using beliefs elicitation methods.

  18. Development and application of an acceptance testing model

    NASA Technical Reports Server (NTRS)

    Pendley, Rex D.; Noonan, Caroline H.; Hall, Kenneth R.

    1992-01-01

    The process of acceptance testing large software systems for NASA has been analyzed, and an empirical planning model of the process constructed. This model gives managers accurate predictions of the staffing needed, the productivity of a test team, and the rate at which the system will pass. Applying the model to a new system shows a high level of agreement between the model and actual performance. The model also gives managers an objective measure of process improvement.

  19. Theoretical models of neural circuit development.

    PubMed

    Simpson, Hugh D; Mortimer, Duncan; Goodhill, Geoffrey J

    2009-01-01

    Proper wiring up of the nervous system is critical to the development of organisms capable of complex and adaptable behaviors. Besides the many experimental advances in determining the cellular and molecular machinery that carries out this remarkable task precisely and robustly, theoretical approaches have also proven to be useful tools in analyzing this machinery. A quantitative understanding of these processes can allow us to make predictions, test hypotheses, and appraise established concepts in a new light. Three areas that have been fruitful in this regard are axon guidance, retinotectal mapping, and activity-dependent development. This chapter reviews some of the contributions made by mathematical modeling in these areas, illustrated by important examples of models in each section. For axon guidance, we discuss models of how growth cones respond to their environment, and how this environment can place constraints on growth cone behavior. Retinotectal mapping looks at computational models for how topography can be generated in populations of neurons based on molecular gradients and other mechanisms such as competition. In activity-dependent development, we discuss theoretical approaches largely based on Hebbian synaptic plasticity rules, and how they can generate maps in the visual cortex very similar to those seen in vivo. We show how theoretical approaches have substantially contributed to the advancement of developmental neuroscience, and discuss future directions for mathematical modeling in the field. PMID:19427515

  20. Determinants of Social Networking Software Acceptance: A Multi-Theoretical Approach

    ERIC Educational Resources Information Center

    Shittu, Ahmed Tajudeen; Madarsha, Kamal Basha; AbduRahman, Nik Suryani Nik; Ahmad, Tunku Badariah Tunku

    2013-01-01

    Understanding reasons why students use social media has become a major preoccupation of researchers in recent time due to the rate of its adoption among the present generation of students. Some of the few study on social media phenomenon employed a single theory as a framework in order to understand the factors that influence the acceptance of it…

  1. A Causal Model of Teacher Acceptance of Technology

    ERIC Educational Resources Information Center

    Chang, Jui-Ling; Lieu, Pang-Tien; Liang, Jung-Hui; Liu, Hsiang-Te; Wong, Seng-lee

    2012-01-01

    This study proposes a causal model for investigating teacher acceptance of technology. We received 258 effective replies from teachers at public and private universities in Taiwan. A questionnaire survey was utilized to test the proposed model. The Lisrel was applied to test the proposed hypotheses. The result shows that computer self-efficacy has…

  2. 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.

  3. Theoretical modeling for the stereo mission

    NASA Astrophysics Data System (ADS)

    Aschwanden, Markus J.; Burlaga, L. F.; Kaiser, M. L.; Ng, C. K.; Reames, D. V.; Reiner, M. J.; Gombosi, T. I.; Lugaz, N.; Manchester, W.; Roussev, I. I.; Zurbuchen, T. H.; Farrugia, C. J.; Galvin, A. B.; Lee, M. A.; Linker, J. A.; Mikić, Z.; Riley, P.; Alexander, D.; Sandman, A. W.; Cook, J. W.; Howard, R. A.; Odstrčil, D.; Pizzo, V. J.; Kóta, J.; Liewer, P. C.; Luhmann, J. G.; Inhester, B.; Schwenn, R. W.; Solanki, S. K.; Vasyliunas, V. M.; Wiegelmann, T.; Blush, L.; Bochsler, P.; Cairns, I. H.; Robinson, P. A.; Bothmer, V.; Kecskemety, K.; Llebaria, A.; Maksimovic, M.; Scholer, M.; Wimmer-Schweingruber, R. F.

    2008-04-01

    We summarize the theory and modeling efforts for the STEREO mission, which will be used to interpret the data of both the remote-sensing (SECCHI, SWAVES) and in-situ instruments (IMPACT, PLASTIC). The modeling includes the coronal plasma, in both open and closed magnetic structures, and the solar wind and its expansion outwards from the Sun, which defines the heliosphere. Particular emphasis is given to modeling of dynamic phenomena associated with the initiation and propagation of coronal mass ejections (CMEs). The modeling of the CME initiation includes magnetic shearing, kink instability, filament eruption, and magnetic reconnection in the flaring lower corona. The modeling of CME propagation entails interplanetary shocks, interplanetary particle beams, solar energetic particles (SEPs), geoeffective connections, and space weather. This review describes mostly existing models of groups that have committed their work to the STEREO mission, but is by no means exhaustive or comprehensive regarding alternative theoretical approaches.

  4. Theoretical models for polarimetric radar clutter

    NASA Technical Reports Server (NTRS)

    Borgeaud, M.; Shin, R. T.; Kong, J. A.

    1987-01-01

    The Mueller matrix and polarization covariance matrix are described for polarimetric radar systems. The clutter is modeled by a layer of random permittivity, described by a three-dimensional correlation function, with variance, and horizontal and vertical correlation lengths. This model is applied, using the wave theory with Born approximations carried to the second order, to find the backscattering elements of the polarimetric matrices. It is found that 8 out of 16 elements of the Mueller matrix are identically zero, corresponding to a covariance matrix with four zero elements. Theoretical predictions are matched with experimental data for vegetation fields.

  5. Theoretical model of Saturn's kilometric radiation spectrum

    NASA Astrophysics Data System (ADS)

    Galopeau, P.; Zarka, P.; Le Queau, D.

    1989-07-01

    A model was developed, which allowed the theoretical derivation of an envelope for the average spectrum of the Saturnian kilometric radiation (SKR), assuming that the SKR is generated by the cyclotron maser instability. The theoretical SKR spectrum derived was found to exhibit the same spectral features as the observed mean spectra. Namely, the overall shape of both calculated and measured spectra are similar, with the fluxes peaking at frequencies of 100,000 Hz and decreasing abruptly at high frequencies, and more slowly at lower frequencies. The calculated spectral intensity levels exceed the most intense observed intensities by up to 1 order of magnitude, suggesting that the SKR emission is only marginally saturated by nonlinear processes.

  6. Examining the Factors Affecting PDA Acceptance among Physicians: An Extended Technology Acceptance Model.

    PubMed

    Basak, Ecem; Gumussoy, Cigdem Altin; Calisir, Fethi

    2015-01-01

    This study aims at identifying the factors affecting the intention to use personal digital assistant (PDA) technology among physicians in Turkey using an extended Technology Acceptance Model (TAM). A structural equation-modeling approach was used to identify the variables that significantly affect the intention to use PDA technology. The data were collected from 339 physicians in Turkey. Results indicated that 71% of the physicians' intention to use PDA technology is explained by perceived usefulness and perceived ease of use. On comparing both, the perceived ease of use has the strongest effect, whereas the effect of perceived enjoyment on behavioral intention to use is found to be insignificant. This study concludes with the recommendations for managers and possible future research.

  7. Theoretical Modeling of Prion Disease Incubation

    PubMed Central

    Kulkarni, R. V.; Slepoy, A.; Singh, R. R. P.; Cox, D. L.; Pázmándi, F.

    2003-01-01

    We apply a theoretical aggregation model to laboratory and epidemiological prion disease incubation time data. In our model, slow growth of misfolded protein aggregates from small initial seeds controls the latent or lag phase; aggregate fissioning and subsequent spreading leads to an exponential growth phase. Our model accounts for the striking reproducibility of incubation times for high dose inoculation of lab animals. In particular, low dose yields broad incubation time distributions, and increasing dose narrows distributions and yields sharply defined onset times. We also explore how incubation time statistics depend upon aggregate morphology. We apply our model to fit the experimental dose-incubation curves for distinct strains of scrapie, and explain logarithmic variation at high dose and deviations from logarithmic behavior at low dose. We use this to make testable predictions for infectivity time-course experiments. PMID:12885622

  8. Predicting User Acceptance of Collaborative Technologies: An Extension of the Technology Acceptance Model for E-Learning

    ERIC Educational Resources Information Center

    Cheung, Ronnie; Vogel, Doug

    2013-01-01

    Collaborative technologies support group work in project-based environments. In this study, we enhance the technology acceptance model to explain the factors that influence the acceptance of Google Applications for collaborative learning. The enhanced model was empirically evaluated using survey data collected from 136 students enrolled in a…

  9. Theoretical models for supercritical fluid extraction.

    PubMed

    Huang, Zhen; Shi, Xiao-Han; Jiang, Wei-Juan

    2012-08-10

    For the proper design of supercritical fluid extraction processes, it is essential to have a sound knowledge of the mass transfer mechanism of the extraction process and the appropriate mathematical representation. In this paper, the advances and applications of kinetic models for describing supercritical fluid extraction from various solid matrices have been presented. The theoretical models overviewed here include the hot ball diffusion, broken and intact cell, shrinking core and some relatively simple models. Mathematical representations of these models have been in detail interpreted as well as their assumptions, parameter identifications and application examples. Extraction process of the analyte solute from the solid matrix by means of supercritical fluid includes the dissolution of the analyte from the solid, the analyte diffusion in the matrix and its transport to the bulk supercritical fluid. Mechanisms involved in a mass transfer model are discussed in terms of external mass transfer resistance, internal mass transfer resistance, solute-solid interactions and axial dispersion. The correlations of the external mass transfer coefficient and axial dispersion coefficient with certain dimensionless numbers are also discussed. Among these models, the broken and intact cell model seems to be the most relevant mathematical model as it is able to provide realistic description of the plant material structure for better understanding the mass-transfer kinetics and thus it has been widely employed for modeling supercritical fluid extraction of natural matters. PMID:22560346

  10. Acceptance of health information technology in health professionals: an application of the revised technology acceptance model.

    PubMed

    Ketikidis, Panayiotis; Dimitrovski, Tomislav; Lazuras, Lambros; Bath, Peter A

    2012-06-01

    The response of health professionals to the use of health information technology (HIT) is an important research topic that can partly explain the success or failure of any HIT application. The present study applied a modified version of the revised technology acceptance model (TAM) to assess the relevant beliefs and acceptance of HIT systems in a sample of health professionals (n = 133). Structured anonymous questionnaires were used and a cross-sectional design was employed. The main outcome measure was the intention to use HIT systems. ANOVA was employed to examine differences in TAM-related variables between nurses and medical doctors, and no significant differences were found. Multiple linear regression analysis was used to assess the predictors of HIT usage intentions. The findings showed that perceived ease of use, but not usefulness, relevance and subjective norms directly predicted HIT usage intentions. The present findings suggest that a modification of the original TAM approach is needed to better understand health professionals' support and endorsement of HIT. Perceived ease of use, relevance of HIT to the medical and nursing professions, as well as social influences, should be tapped by information campaigns aiming to enhance support for HIT in healthcare settings.

  11. ICT & OTs: a model of information and communications technology acceptance and utilisation by occupational therapists (part 2).

    PubMed

    Schaper, Louise; Pervan, Graham

    2007-01-01

    The research reported in this paper describes the development, empirical validation and analysis of a model of technology acceptance by Australian occupational therapists. The study described involved the collection of quantitative data through a national survey. The theoretical significance of this work is that it uses a thoroughly constructed research model, with one of the largest sample sizes ever tested (n=1605), to extend technology acceptance research into the health sector. Results provide strong support for the model. This work reveals the complexity of the constructs and relationships that influence technology acceptance and highlights the need to include sociotechnical and system issues in studies of technology acceptance in healthcare to improve information system implementation success in this arena. The results of this study have practical and theoretical implications for health informaticians and researchers in the field of health informatics and information systems, tertiary educators, Commonwealth and State Governments and the allied health professions.

  12. A Theoretical Model of Water and Trade

    NASA Astrophysics Data System (ADS)

    Dang, Q.; Konar, M.; Reimer, J.; Di Baldassarre, G.; Lin, X.; Zeng, R.

    2015-12-01

    Water is an essential factor of agricultural production. Agriculture, in turn, is globalized through the trade of food commodities. In this paper, we develop a theoretical model of a small open economy that explicitly incorporates water resources. The model emphasizes three tradeoffs involving water decision-making that are important yet not always considered within the existing literature. One tradeoff focuses on competition for water among different sectors when there is a shock to one of the sectors only, such as trade liberalization and consequent higher demand for the product. A second tradeoff concerns the possibility that there may or may not be substitutes for water, such as increased use of sophisticated irrigation technology as a means to increase crop output in the absence of higher water availability. A third tradeoff explores the possibility that the rest of the world can be a source of supply or demand for a country's water-using products. A number of propositions are proven. For example, while trade liberalization tends to increase water use, increased pressure on water supplies can be moderated by way of a tax that is derivable with observable economic phenomena. Another example is that increased riskiness of water availability tends to cause water users to use less water than would be the case under profit maximization. These theoretical model results generate hypotheses that can be tested empirically in future work.

  13. Acceptance of technology-enhanced learning for a theoretical radiological science course: a randomized controlled trial

    PubMed Central

    2012-01-01

    Background Technology-enhanced learning (TEL) gives a view to improved education. However, there is a need to clarify how TEL can be used effectively. The study compared students' attitudes and opinions towards a traditional face-to-face course on theoretical radiological science and a TEL course where students could combine face-to-face lectures and e-learning modules at their best convenience. Methods 42 third-year dental students were randomly assigned to the traditional face-to-face group and the TEL group. Both groups completed questionnaires before the beginning and after completion of the course on attitudes and opinions towards a traditional face-to-face lectures and technology-enhanced learning. After completion of the course both groups also filled in the validated German-language TRIL (Trierer Inventar zur Lehrevaluation) questionnaire for the evaluation of courses given at universities. Results Both groups had a positive attitude towards e-learning that did not change over time. The TEL group attended significantly less face-to-face lectures than the traditional group. However, both groups stated that face-to-face lectures were the basis for education in a theoretical radiological science course. The members of the TEL group rated e-mail reminders significantly more important when they filled in the questionnaire on attitudes and opinions towards a traditional face-to-face lectures and technology-enhanced learning for the second time after completion of the course. The members of the technology-enhanced learning group were significantly less confident in passing the exam compared to the members of the traditional group. However, examination results did not differ significantly for traditional and the TEL group. Conclusions It seems that technology-enhanced learning in a theoretical radiological science course has the potential to reduce the need for face-to-face lectures. At the same time examination results are not impaired. However, technology

  14. A theoretical model of water and trade

    NASA Astrophysics Data System (ADS)

    Dang, Qian; Konar, Megan; Reimer, Jeffrey J.; Di Baldassarre, Giuliano; Lin, Xiaowen; Zeng, Ruijie

    2016-03-01

    Water is an essential input for agricultural production. Agriculture, in turn, is globalized through the trade of agricultural commodities. In this paper, we develop a theoretical model that emphasizes four tradeoffs involving water-use decision-making that are important yet not always considered in a consistent framework. One tradeoff focuses on competition for water among different economic sectors. A second tradeoff examines the possibility that certain types of agricultural investments can offset water use. A third tradeoff explores the possibility that the rest of the world can be a source of supply or demand for a country's water-using commodities. The fourth tradeoff concerns how variability in water supplies influences farmer decision-making. We show conditions under which trade liberalization affect water use. Two policy scenarios to reduce water use are evaluated. First, we derive a target tax that reduces water use without offsetting the gains from trade liberalization, although important tradeoffs exist between economic performance and resource use. Second, we show how subsidization of water-saving technologies can allow producers to use less water without reducing agricultural production, making such subsidization an indirect means of influencing water use decision-making. Finally, we outline conditions under which riskiness of water availability affects water use. These theoretical model results generate hypotheses that can be tested empirically in future work.

  15. Theoretical Models of the Galactic Bulge

    NASA Astrophysics Data System (ADS)

    Shen, Juntai; Li, Zhao-Yu

    Near infrared images from the COBE satellite presented the first clear evidence that our Milky Way galaxy contains a boxy shaped bulge. Recent years have witnessed a gradual paradigm shift in the formation and evolution of the Galactic bulge. Bulges were commonly believed to form in the dynamical violence of galaxy mergers. However, it has become increasingly clear that the main body of the Milky Way bulge is not a classical bulge made by previous major mergers, instead it appears to be a bar seen somewhat end-on. The Milky Way bar can form naturally from a precursor disc and thicken vertically by the internal firehose/buckling instability, giving rise to the boxy appearance. This picture is supported by many lines of evidence, including the asymmetric parallelogram shape, the strong cylindrical rotation (i.e., nearly constant rotation regardless of the height above the disc plane), the existence of an intriguing X-shaped structure in the bulge, and perhaps the metallicity gradients. We review the major theoretical models and techniques to understand the Milky Way bulge. Despite the progresses in recent theoretical attempts, a complete bulge formation model that explains the full kinematics and metallicity distribution is still not fully understood. Upcoming large surveys are expected to shed new light on the formation history of the Galactic bulge.

  16. Electron microscopy and theoretical modeling of cochleates.

    PubMed

    Nagarsekar, Kalpa; Ashtikar, Mukul; Thamm, Jana; Steiniger, Frank; Schacher, Felix; Fahr, Alfred; May, Sylvio

    2014-11-11

    Cochleates are self-assembled cylindrical condensates that consist of large rolled-up lipid bilayer sheets and represent a novel platform for oral and systemic delivery of therapeutically active medicinal agents. With few preceding investigations, the physical basis of cochleate formation has remained largely unexplored. We address the structure and stability of cochleates in a combined experimental/theoretical approach. Employing different electron microscopy methods, we provide evidence for cochleates consisting of phosphatidylserine and calcium to be hollow tubelike structures with a well-defined constant lamellar repeat distance and statistically varying inner and outer radii. To rationalize the relation between inner and outer radii, we propose a theoretical model. Based on the minimization of a phenomenological free energy expression containing a bending, adhesion, and frustration contribution, we predict the optimal tube dimensions of a cochleate and estimate ratios of material constants for cochleates consisting of phosphatidylserines with varied hydrocarbon chain structures. Knowing and understanding these ratios will ultimately benefit the successful formulation of cochleates for drug delivery applications.

  17. Modeling of the charge acceptance of lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Thele, M.; Schiffer, J.; Karden, E.; Surewaard, E.; Sauer, D. U.

    This paper presents a model for flooded and VRLA batteries that is parameterized by impedance spectroscopy and includes the overcharging effects to allow charge-acceptance simulations (e.g. for regenerative-braking drive-cycle profiles). The full dynamic behavior and the short-term charge/discharge history is taken into account. This is achieved by a detailed modeling of the sulfate crystal growth and modeling of the internal gas recombination cycle. The model is applicable in the full realistic temperature and current range of automotive applications. For model validation, several load profiles (covering the dynamics and the current range appearing in electrically assisted or hybrid cars) are examined and the charge-acceptance limiting effects are elaborately discussed. The validation measurements have been performed for different types of lead-acid batteries (flooded and VRLA). The model is therefore an important tool for the development of automotive power nets, but it also allows to analyze different charging strategies and energy gains which can be achieved during regenerative-braking.

  18. Explaining Facial Imitation: A Theoretical Model

    PubMed Central

    Meltzoff, Andrew N.; Moore, M. Keith

    2013-01-01

    A long-standing puzzle in developmental psychology is how infants imitate gestures they cannot see themselves perform (facial gestures). Two critical issues are: (a) the metric infants use to detect cross-modal equivalences in human acts and (b) the process by which they correct their imitative errors. We address these issues in a detailed model of the mechanisms underlying facial imitation. The model can be extended to encompass other types of imitation. The model capitalizes on three new theoretical concepts. First, organ identification is the means by which infants relate parts of their own bodies to corresponding ones of the adult’s. Second, body babbling (infants’ movement practice gained through self-generated activity) provides experience mapping movements to the resulting body configurations. Third, organ relations provide the metric by which infant and adult acts are perceived in commensurate terms. In imitating, infants attempt to match the organ relations they see exhibited by the adults with those they feel themselves make. We show how development restructures the meaning and function of early imitation. We argue that important aspects of later social cognition are rooted in the initial cross-modal equivalence between self and other found in newborns. PMID:24634574

  19. Information-Theoretic Perspectives on Geophysical Models

    NASA Astrophysics Data System (ADS)

    Nearing, Grey

    2016-04-01

    practice of science (except by Gong et al., 2013, whose fundamental insight is the basis for this talk), and here I offer two examples of practical methods that scientists might use to approximately measure ontological information. I place this practical discussion in the context of several recent and high-profile experiments that have found that simple out-of-sample statistical models typically (vastly) outperform our most sophisticated terrestrial hydrology models. I offer some perspective on several open questions about how to use these findings to improve our models and understanding of these systems. Cartwright, N. (1983) How the Laws of Physics Lie. New York, NY: Cambridge Univ Press. Clark, M. P., Kavetski, D. and Fenicia, F. (2011) 'Pursuing the method of multiple working hypotheses for hydrological modeling', Water Resources Research, 47(9). Cover, T. M. and Thomas, J. A. (1991) Elements of Information Theory. New York, NY: Wiley-Interscience. Cox, R. T. (1946) 'Probability, frequency and reasonable expectation', American Journal of Physics, 14, pp. 1-13. Csiszár, I. (1972) 'A Class of Measures of Informativity of Observation Channels', Periodica Mathematica Hungarica, 2(1), pp. 191-213. Davies, P. C. W. (1990) 'Why is the physical world so comprehensible', Complexity, entropy and the physics of information, pp. 61-70. Gong, W., Gupta, H. V., Yang, D., Sricharan, K. and Hero, A. O. (2013) 'Estimating Epistemic & Aleatory Uncertainties During Hydrologic Modeling: An Information Theoretic Approach', Water Resources Research, 49(4), pp. 2253-2273. Jaynes, E. T. (2003) Probability Theory: The Logic of Science. New York, NY: Cambridge University Press. Nearing, G. S. and Gupta, H. V. (2015) 'The quantity and quality of information in hydrologic models', Water Resources Research, 51(1), pp. 524-538. Popper, K. R. (2002) The Logic of Scientific Discovery. New York: Routledge. Van Horn, K. S. (2003) 'Constructing a logic of plausible inference: a guide to cox's theorem

  20. Evaluation of teledermatology adoption by health-care professionals using a modified Technology Acceptance Model.

    PubMed

    Orruño, Estibalitz; Gagnon, Marie Pierre; Asua, José; Ben Abdeljelil, Anis

    2011-01-01

    We examined the main factors affecting the intention of physicians to use teledermatology using a modified Technology Acceptance Model (TAM). The investigation was carried out during a teledermatology pilot study conducted in Spain. A total of 276 questionnaires were sent to physicians by email and 171 responded (62%). Cronbach's alpha was acceptably high for all constructs. Theoretical variables were well correlated with each other and with the dependent variable (Intention to Use). Logistic regression indicated that the original TAM model was good at predicting physicians' intention to use teledermatology and that the variables Perceived Usefulness and Perceived Ease of Use were both significant (odds ratios of 8.4 and 7.4, respectively). When other theoretical variables were added, the model was still significant and it also became more powerful. However, the only significant predictor in the modified model was Facilitators with an odds ratio of 9.9. Thus the TAM was good at predicting physicians' intention to use teledermatology. However, the most important variable was the perception of Facilitators to using the technology (e.g. infrastructure, training and support).

  1. Factors Influencing the Acceptance of Web-Based Training in Malaysia: Applying the Technology Acceptance Model

    ERIC Educational Resources Information Center

    Hashim, Junaidah

    2008-01-01

    Companies in Malaysia are beginning to use web-based training to reduce the cost of training and to provide employees with greater access to instruction. However, some people are uncomfortable with technology and prefer person-to-person methods of training. This study examines the acceptance of web-based training among a convenience sample of 261…

  2. Assessing a Theoretical Model on EFL College Students

    ERIC Educational Resources Information Center

    Chang, Yu-Ping

    2011-01-01

    This study aimed to (1) integrate relevant language learning models and theories, (2) construct a theoretical model of college students' English learning performance, and (3) assess the model fit between empirically observed data and the theoretical model proposed by the researchers of this study. Subjects of this study were 1,129 Taiwanese EFL…

  3. How prayer heals: a theoretical model.

    PubMed

    Levin, J S

    1996-01-01

    This article presents a theoretical model that outlines various possible explanations for the healing effects of prayer. Four classes of mechanisms are defined on the basis of whether healing has naturalistic or supernatural origins and whether it operates locally or nonlocally. Through this framework, most of the currently proposed hypotheses for understanding absent healing and other related phenomena-hypotheses that invoke such concepts as subtle energy, psi, consciousness, morphic fields, and extended mind-are shown to be no less naturalistic than the Newtonian, mechanistic forces of allopathic biomedicine so often derided for their materialism. In proposing that prayer may heal through nonlocal means according to mechanisms and theories proposed by the new physics, Dossey is almost alone among medical scholars in suggesting the possible limitations and inadequacies of hypotheses based on energies, forces, and fields. Yet even such nonlocal effects can be conceived of as naturalistic; that is, they are explained by physical laws that may be unbelievable or unfamiliar to most physicians but that are nonetheless becoming recognized as operant laws of the natural universe. The concept of the supernatural, however, is something altogether different, and is, by definition, outside of or beyond nature. Herein may reside an either wholly or partly transcendent Creator-God who is believed by many to heal through means that transcend the laws of the created universe, both its local and nonlocal elements, and that are thus inherently inaccessible to and unknowable by science. Such an explanation for the effects of prayer merits consideration and, despite its unprovability by medical science, should not be dismissed out of hand.

  4. How prayer heals: a theoretical model.

    PubMed

    Levin, J S

    1996-01-01

    This article presents a theoretical model that outlines various possible explanations for the healing effects of prayer. Four classes of mechanisms are defined on the basis of whether healing has naturalistic or supernatural origins and whether it operates locally or nonlocally. Through this framework, most of the currently proposed hypotheses for understanding absent healing and other related phenomena-hypotheses that invoke such concepts as subtle energy, psi, consciousness, morphic fields, and extended mind-are shown to be no less naturalistic than the Newtonian, mechanistic forces of allopathic biomedicine so often derided for their materialism. In proposing that prayer may heal through nonlocal means according to mechanisms and theories proposed by the new physics, Dossey is almost alone among medical scholars in suggesting the possible limitations and inadequacies of hypotheses based on energies, forces, and fields. Yet even such nonlocal effects can be conceived of as naturalistic; that is, they are explained by physical laws that may be unbelievable or unfamiliar to most physicians but that are nonetheless becoming recognized as operant laws of the natural universe. The concept of the supernatural, however, is something altogether different, and is, by definition, outside of or beyond nature. Herein may reside an either wholly or partly transcendent Creator-God who is believed by many to heal through means that transcend the laws of the created universe, both its local and nonlocal elements, and that are thus inherently inaccessible to and unknowable by science. Such an explanation for the effects of prayer merits consideration and, despite its unprovability by medical science, should not be dismissed out of hand. PMID:8795874

  5. The History of UTAUT Model and Its Impact on ICT Acceptance and Usage by Academicians

    ERIC Educational Resources Information Center

    Oye, N. D.; Iahad, N. A.; Rahim, N. Ab.

    2014-01-01

    This paper started with the review of the history of technology acceptance model from TRA to UTAUT. The expected contribution is to bring to lime light the current development stage of the technology acceptance model. Based on this, the paper examined the impact of UTAUT model on ICT acceptance and usage in HEIs. The UTAUT model theory was…

  6. Influence of Gender and Computer Teaching Efficacy on Computer Acceptance among Malaysian Student Teachers: An Extended Technology Acceptance Model

    ERIC Educational Resources Information Center

    Wong, Kung-Teck; Teo, Timothy; Russo, Sharon

    2012-01-01

    The purpose of this study is to validate the technology acceptance model (TAM) in an educational context and explore the role of gender and computer teaching efficacy as external variables. From the literature, it appeared that only limited studies had developed models to explain statistically the chain of influence of computer teaching efficacy…

  7. A comprehensive examination of the model underlying acceptance and commitment therapy for chronic pain.

    PubMed

    Vowles, Kevin E; Sowden, Gail; Ashworth, Julie

    2014-05-01

    The therapeutic model underlying Acceptance and Commitment Therapy (ACT) is reasonably well-established as it applies to chronic pain. Several studies have examined measures of single ACT processes, or subsets of processes, and have almost uniformly indicated reliable relations with patient functioning. To date, however, no study has performed a comprehensive examination of the entire ACT model, including all of its component processes, as it relates to functioning. The present study performed this examination in 274 individuals with chronic pain presenting for an assessment appointment. Participants completed a battery of self-report questionnaires, assessing multiple aspects of the ACT model, as well as pain intensity, disability, and emotional distress. Initial exploratory factor analyses examined measures of the ACT model and measures of patient functioning separately with each analysis identifying three factors. Next, the fit of a model including ACT processes on the one hand and patient functioning on the other was examined using Structural Equation Modeling. Overall model fit was acceptable and indicated moderate correlations among the ACT processes themselves, as well as significant relations with pain intensity, emotional distress, and disability. These analyses build on the existing literature by providing, to our knowledge, the most comprehensive evaluation of the ACT theoretical model in chronic pain to date.

  8. Identifying Ghanaian Pre-Service Teachers' Readiness for Computer Use: A Technology Acceptance Model Approach

    ERIC Educational Resources Information Center

    Gyamfi, Stephen Adu

    2016-01-01

    This study extends the technology acceptance model to identify factors that influence technology acceptance among pre-service teachers in Ghana. Data from 380 usable questionnaires were tested against the research model. Utilising the extended technology acceptance model (TAM) as a research framework, the study found that: pre-service teachers'…

  9. Modeling eBook acceptance: A study on mathematics teachers

    NASA Astrophysics Data System (ADS)

    Jalal, Azlin Abd; Ayub, Ahmad Fauzi Mohd; Tarmizi, Rohani Ahmad

    2014-12-01

    The integration and effectiveness of eBook utilization in Mathematics teaching and learning greatly relied upon the teachers, hence the need to understand their perceptions and beliefs. The eBook, an individual laptop completed with digitized textbook sofwares, were provided for each students in line with the concept of 1 student:1 laptop. This study focuses on predicting a model on the acceptance of the eBook among Mathematics teachers. Data was collected from 304 mathematics teachers in selected schools using a survey questionnaire. The selection were based on the proportionate stratified sampling. Structural Equation Modeling (SEM) were employed where the model was tested and evaluated and was found to have a good fit. The variance explained for the teachers' attitude towards eBook is approximately 69.1% where perceived usefulness appeared to be a stronger determinant compared to perceived ease of use. This study concluded that the attitude of mathematics teachers towards eBook depends largely on the perception of how useful the eBook is on improving their teaching performance, implying that teachers should be kept updated with the latest mathematical application and sofwares to use with the eBook to ensure positive attitude towards using it in class.

  10. Expanding Panjabi's stability model to express movement: a theoretical model.

    PubMed

    Hoffman, J; Gabel, P

    2013-06-01

    Novel theoretical models of movement have historically inspired the creation of new methods for the application of human movement. The landmark theoretical model of spinal stability by Panjabi in 1992 led to the creation of an exercise approach to spinal stability. This approach however was later challenged, most significantly due to a lack of favourable clinical effect. The concepts explored in this paper address and consider the deficiencies of Panjabi's model then propose an evolution and expansion from a special model of stability to a general one of movement. It is proposed that two body-wide symbiotic elements are present within all movement systems, stability and mobility. The justification for this is derived from the observable clinical environment. It is clinically recognised that these two elements are present and identifiable throughout the body in different joints and muscles, and the neural conduction system. In order to generalise the Panjabi model of stability to include and illustrate movement, a matching parallel mobility system with the same subsystems was conceptually created. In this expanded theoretical model, the new mobility system is placed beside the existing stability system and subsystems. The ability of both stability and mobility systems to work in harmony will subsequently determine the quality of movement. Conversely, malfunction of either system, or their subsystems, will deleteriously affect all other subsystems and consequently overall movement quality. For this reason, in the rehabilitation exercise environment, focus should be placed on the simultaneous involvement of both the stability and mobility systems. It is suggested that the individual's relevant functional harmonious movements should be challenged at the highest possible level without pain or discomfort. It is anticipated that this conceptual expansion of the theoretical model of stability to one with the symbiotic inclusion of mobility, will provide new understandings

  11. A theoretical model of atmospheric ozone depletion

    NASA Astrophysics Data System (ADS)

    Midya, S. K.; Jana, P. K.; Lahiri, T.

    1994-01-01

    A critical study on different ozone depletion and formation processes has been made and following important results are obtained: (i) From analysis it is shown that O3 concentration will decrease very minutely with time for normal atmosphere when [O], [O2] and UV-radiation remain constant. (ii) An empirical equation is established theoretically between the variation of ozone concentration and time. (iii) Special ozone depletion processes are responsible for the dramatic decrease of O3-concentration at Antarctica.

  12. Nurses' self-relation--becoming theoretically competent: the SAUC model for confirming nursing.

    PubMed

    Gustafsson, Barbro; Willman, Ania M

    2003-07-01

    The purpose of this study was to acquire an understanding of how nurses' self-relation (view of themselves as nurses) was influenced in connection with implementation of a nursing theory, the sympathy-acceptance-understanding-competence model for confirming nursing. This model was developed by Gustafsson and Pörn. Twenty-two nurses' written statements evaluating mentoring during the six-month implementation process in elder care, were analyzed hermeneutically with the hypothetic-deductive method. An action-theoretic and confirmatory approach was used for facilitating theoretically specified hypotheses. The nurses increased their ability to describe nursing theoretically and gained a foundation of common nursing values. The results provided an understanding of how nurses' self-relation was strengthened by becoming theoretically competent. PMID:12876885

  13. Nurses' self-relation--becoming theoretically competent: the SAUC model for confirming nursing.

    PubMed

    Gustafsson, Barbro; Willman, Ania M

    2003-07-01

    The purpose of this study was to acquire an understanding of how nurses' self-relation (view of themselves as nurses) was influenced in connection with implementation of a nursing theory, the sympathy-acceptance-understanding-competence model for confirming nursing. This model was developed by Gustafsson and Pörn. Twenty-two nurses' written statements evaluating mentoring during the six-month implementation process in elder care, were analyzed hermeneutically with the hypothetic-deductive method. An action-theoretic and confirmatory approach was used for facilitating theoretically specified hypotheses. The nurses increased their ability to describe nursing theoretically and gained a foundation of common nursing values. The results provided an understanding of how nurses' self-relation was strengthened by becoming theoretically competent.

  14. Confronting theoretical models with CANDELS observations

    NASA Astrophysics Data System (ADS)

    Lu, Yu; CANDELS Collaboration

    2014-01-01

    Current galaxy formation models contain large uncertainties in modeling gas accretion, star formation and feedback processes. These uncertainties can only be constrained by comprehensive and careful model-data comparisons. Three independently developed semi-analytic galaxy formation models are adopted to make predictions for CANDELS observations. A comparison study involving the three different models reveals both common features shared by the models and discrepancies between the models. The similarities in the predicted stellar mass functions indicate strong degeneracies between the models, which can only be broken by accurate measurements of the stellar mass functions at multiple redshifts. On the other hand, the models show large discrepancies in their predicted star formation histories and metallicity-stellar mass relations. These discrepancies stem from the uncertainties in modeling gas accretion and galactic outflow powered by feedback. The model comparisons suggest that, other than directly constraining inflow and outflow in observation, more accurate observational measurements for stellar mass, star formation rate and metallicity of galaxies in a large range of cosmic epoch will discriminate between models. Our study involving multiple models and exploration of the high-dimensional parameter space demonstrates that analysis of the full CANDELS dataset, including a self-consistent treatment of star formation rates, stellar masses, galaxy sizes, metallicity relations and their evolution across a broad redshift range, is likely to significantly tighten the data constraints and shed light on understanding the physics governing galaxy formation.

  15. Empathy and Child Neglect: A Theoretical Model

    ERIC Educational Resources Information Center

    De Paul, Joaquin; Guibert, Maria

    2008-01-01

    Objective: To present an explanatory theory-based model of child neglect. This model does not address neglectful behaviors of parents with mental retardation, alcohol or drug abuse, or severe mental health problems. In this model parental behavior aimed to satisfy a child's need is considered a helping behavior and, as a consequence, child neglect…

  16. A theoretical model to study melting of metals under pressure

    NASA Astrophysics Data System (ADS)

    Kholiya, Kuldeep; Chandra, Jeewan

    2015-10-01

    On the basis of the thermal equation-of-state a simple theoretical model is developed to study the pressure dependence of melting temperature. The model is then applied to compute the high pressure melting curve of 10 metals (Cu, Mg, Pb, Al, In, Cd, Zn, Au, Ag and Mn). It is found that the melting temperature is not linear with pressure and the slope dTm/dP of the melting curve decreases continuously with the increase in pressure. The results obtained with the present model are also compared with the previous theoretical and experimental data. A good agreement between theoretical and experimental result supports the validity of the present model.

  17. Theoretical Frameworks for Multiscale Modeling and Simulation

    PubMed Central

    Zhou, Huan-Xiang

    2014-01-01

    Biomolecular systems have been modeled at a variety of scales, ranging from explicit treatment of electrons and nuclei to continuum description of bulk deformation or velocity. Many challenges of interfacing between scales have been overcome. Multiple models at different scales have been used to study the same system or calculate the same property (e.g., channel conductance). Accurate modeling of biochemical processes under in vivo conditions and the bridging of molecular and subcellular scales will likely soon become reality. PMID:24492203

  18. Information-Theoretic Perspectives on Geophysical Models

    NASA Astrophysics Data System (ADS)

    Nearing, Grey

    2016-04-01

    To test any hypothesis about any dynamic system, it is necessary to build a model that places that hypothesis into the context of everything else that we know about the system: initial and boundary conditions and interactions between various governing processes (Hempel and Oppenheim, 1948, Cartwright, 1983). No hypothesis can be tested in isolation, and no hypothesis can be tested without a model (for a geoscience-related discussion see Clark et al., 2011). Science is (currently) fundamentally reductionist in the sense that we seek some small set of governing principles that can explain all phenomena in the universe, and such laws are ontological in the sense that they describe the object under investigation (Davies, 1990 gives several competing perspectives on this claim). However, since we cannot build perfect models of complex systems, any model that does not also contain an epistemological component (i.e., a statement, like a probability distribution, that refers directly to the quality of of the information from the model) is falsified immediately (in the sense of Popper, 2002) given only a small number of observations. Models necessarily contain both ontological and epistemological components, and what this means is that the purpose of any robust scientific method is to measure the amount and quality of information provided by models. I believe that any viable philosophy of science must be reducible to this statement. The first step toward a unified theory of scientific models (and therefore a complete philosophy of science) is a quantitative language that applies to both ontological and epistemological questions. Information theory is one such language: Cox' (1946) theorem (see Van Horn, 2003) tells us that probability theory is the (only) calculus that is consistent with Classical Logic (Jaynes, 2003; chapter 1), and information theory is simply the integration of convex transforms of probability ratios (integration reduces density functions to scalar

  19. Toward a Theoretical Model of Evaluation Utilization.

    ERIC Educational Resources Information Center

    Johnson, R. Burke

    1998-01-01

    A metamodel of evaluation utilization was developed from implicit and explicit process models and ideas developed in recent research. The model depicts evaluation use as occurring in an internal environment situated in an external environment. Background variables, international or social psychological variables, and evaluation use variables are…

  20. A Detection-Theoretic Model of Echo Inhibition

    ERIC Educational Resources Information Center

    Saberi, Kourosh; Petrosyan, Agavni

    2004-01-01

    A detection-theoretic analysis of the auditory localization of dual-impulse stimuli is described, and a model for the processing of spatial cues in the echo pulse is developed. Although for over 50 years "echo suppression" has been the topic of intense theoretical and empirical study within the hearing sciences, only a rudimentary understanding of…

  1. A Theoretical Framework for Physics Education Research: Modeling Student Thinking

    ERIC Educational Resources Information Center

    Redish, Edward F.

    2004-01-01

    Education is a goal-oriented field. But if we want to treat education scientifically so we can accumulate, evaluate, and refine what we learn, then we must develop a theoretical framework that is strongly rooted in objective observations and through which different theoretical models of student thinking can be compared. Much that is known in the…

  2. Theoretical analysis and modeling for nanoelectronics

    NASA Astrophysics Data System (ADS)

    Baccarani, Giorgio; Gnani, Elena; Gnudi, Antonio; Reggiani, Susanna

    2016-11-01

    In this paper we review the evolution of Microelectronics and its transformation into Nanoelectronics, following the predictions of Moore's law, and some of the issues related with this evolution. Next, we discuss the requirements of device modeling and the solutions proposed throughout the years to address the physical effects related with an extreme device miniaturization, such as hot-electron effects, band splitting into multiple sub-bands, quasi-ballistic transport and electron tunneling. The most important physical models are shortly highlighted, and a few simulation results of heterojunction TFETs are reported and discussed.

  3. Theoretical Model for Nanoporous Carbon Supercapacitors

    SciTech Connect

    Sumpter, Bobby G; Meunier, Vincent; Huang, Jingsong

    2008-01-01

    The unprecedented anomalous increase in capacitance of nanoporous carbon supercapacitors at pore sizes smaller than 1 nm [Science 2006, 313, 1760.] challenges the long-held presumption that pores smaller than the size of solvated electrolyte ions do not contribute to energy storage. We propose a heuristic model to replace the commonly used model for an electric double-layer capacitor (EDLC) on the basis of an electric double-cylinder capacitor (EDCC) for mesopores (2 {50 nm pore size), which becomes an electric wire-in-cylinder capacitor (EWCC) for micropores (< 2 nm pore size). Our analysis of the available experimental data in the micropore regime is confirmed by 1st principles density functional theory calculations and reveals significant curvature effects for carbon capacitance. The EDCC (and/or EWCC) model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration and dielectric constant, and solute ion size. The new model not only explains the experimental data, but also offers a practical direction for the optimization of the properties of carbon supercapacitors through experiments.

  4. The Adult Roles Models Program: Feasibility, Acceptability, and Initial Outcomes

    PubMed Central

    Silver, Ellen Johnson; Dean, Randa; Perez, Amanda; Rivera, Angelic

    2014-01-01

    We present the feasibility and acceptability of a parent sexuality education program led by peer educators in community settings. We also report the results of an outcome evaluation with 71 parents who were randomized to the intervention or a control group, and surveyed one month prior to and six months after the 4-week intervention. The program was highly feasible and acceptable to participants, and the curriculum was implemented with a high level of fidelity and facilitator quality. Pilot data show promising outcomes for increasing parental knowledge, communication, and monitoring of their adolescent children. PMID:24883051

  5. Theoretical Tinnitus Framework: A Neurofunctional Model.

    PubMed

    Ghodratitoostani, Iman; Zana, Yossi; Delbem, Alexandre C B; Sani, Siamak S; Ekhtiari, Hamed; Sanchez, Tanit G

    2016-01-01

    Subjective tinnitus is the conscious (attended) awareness perception of sound in the absence of an external source and can be classified as an auditory phantom perception. Earlier literature establishes three distinct states of conscious perception as unattended, attended, and attended awareness conscious perception. The current tinnitus development models depend on the role of external events congruently paired with the causal physical events that precipitate the phantom perception. We propose a novel Neurofunctional Tinnitus Model to indicate that the conscious (attended) awareness perception of phantom sound is essential in activating the cognitive-emotional value. The cognitive-emotional value plays a crucial role in governing attention allocation as well as developing annoyance within tinnitus clinical distress. Structurally, the Neurofunctional Tinnitus Model includes the peripheral auditory system, the thalamus, the limbic system, brainstem, basal ganglia, striatum, and the auditory along with prefrontal cortices. Functionally, we assume the model includes presence of continuous or intermittent abnormal signals at the peripheral auditory system or midbrain auditory paths. Depending on the availability of attentional resources, the signals may or may not be perceived. The cognitive valuation process strengthens the lateral-inhibition and noise canceling mechanisms in the mid-brain, which leads to the cessation of sound perception and renders the signal evaluation irrelevant. However, the "sourceless" sound is eventually perceived and can be cognitively interpreted as suspicious or an indication of a disease in which the cortical top-down processes weaken the noise canceling effects. This results in an increase in cognitive and emotional negative reactions such as depression and anxiety. The negative or positive cognitive-emotional feedbacks within the top-down approach may have no relation to the previous experience of the patients. They can also be

  6. Theoretical Tinnitus Framework: A Neurofunctional Model

    PubMed Central

    Ghodratitoostani, Iman; Zana, Yossi; Delbem, Alexandre C. B.; Sani, Siamak S.; Ekhtiari, Hamed; Sanchez, Tanit G.

    2016-01-01

    Subjective tinnitus is the conscious (attended) awareness perception of sound in the absence of an external source and can be classified as an auditory phantom perception. Earlier literature establishes three distinct states of conscious perception as unattended, attended, and attended awareness conscious perception. The current tinnitus development models depend on the role of external events congruently paired with the causal physical events that precipitate the phantom perception. We propose a novel Neurofunctional Tinnitus Model to indicate that the conscious (attended) awareness perception of phantom sound is essential in activating the cognitive-emotional value. The cognitive-emotional value plays a crucial role in governing attention allocation as well as developing annoyance within tinnitus clinical distress. Structurally, the Neurofunctional Tinnitus Model includes the peripheral auditory system, the thalamus, the limbic system, brainstem, basal ganglia, striatum, and the auditory along with prefrontal cortices. Functionally, we assume the model includes presence of continuous or intermittent abnormal signals at the peripheral auditory system or midbrain auditory paths. Depending on the availability of attentional resources, the signals may or may not be perceived. The cognitive valuation process strengthens the lateral-inhibition and noise canceling mechanisms in the mid-brain, which leads to the cessation of sound perception and renders the signal evaluation irrelevant. However, the “sourceless” sound is eventually perceived and can be cognitively interpreted as suspicious or an indication of a disease in which the cortical top-down processes weaken the noise canceling effects. This results in an increase in cognitive and emotional negative reactions such as depression and anxiety. The negative or positive cognitive-emotional feedbacks within the top-down approach may have no relation to the previous experience of the patients. They can also be

  7. Theoretical Tinnitus Framework: A Neurofunctional Model.

    PubMed

    Ghodratitoostani, Iman; Zana, Yossi; Delbem, Alexandre C B; Sani, Siamak S; Ekhtiari, Hamed; Sanchez, Tanit G

    2016-01-01

    Subjective tinnitus is the conscious (attended) awareness perception of sound in the absence of an external source and can be classified as an auditory phantom perception. Earlier literature establishes three distinct states of conscious perception as unattended, attended, and attended awareness conscious perception. The current tinnitus development models depend on the role of external events congruently paired with the causal physical events that precipitate the phantom perception. We propose a novel Neurofunctional Tinnitus Model to indicate that the conscious (attended) awareness perception of phantom sound is essential in activating the cognitive-emotional value. The cognitive-emotional value plays a crucial role in governing attention allocation as well as developing annoyance within tinnitus clinical distress. Structurally, the Neurofunctional Tinnitus Model includes the peripheral auditory system, the thalamus, the limbic system, brainstem, basal ganglia, striatum, and the auditory along with prefrontal cortices. Functionally, we assume the model includes presence of continuous or intermittent abnormal signals at the peripheral auditory system or midbrain auditory paths. Depending on the availability of attentional resources, the signals may or may not be perceived. The cognitive valuation process strengthens the lateral-inhibition and noise canceling mechanisms in the mid-brain, which leads to the cessation of sound perception and renders the signal evaluation irrelevant. However, the "sourceless" sound is eventually perceived and can be cognitively interpreted as suspicious or an indication of a disease in which the cortical top-down processes weaken the noise canceling effects. This results in an increase in cognitive and emotional negative reactions such as depression and anxiety. The negative or positive cognitive-emotional feedbacks within the top-down approach may have no relation to the previous experience of the patients. They can also be

  8. Theoretical Tinnitus Framework: A Neurofunctional Model

    PubMed Central

    Ghodratitoostani, Iman; Zana, Yossi; Delbem, Alexandre C. B.; Sani, Siamak S.; Ekhtiari, Hamed; Sanchez, Tanit G.

    2016-01-01

    Subjective tinnitus is the conscious (attended) awareness perception of sound in the absence of an external source and can be classified as an auditory phantom perception. Earlier literature establishes three distinct states of conscious perception as unattended, attended, and attended awareness conscious perception. The current tinnitus development models depend on the role of external events congruently paired with the causal physical events that precipitate the phantom perception. We propose a novel Neurofunctional Tinnitus Model to indicate that the conscious (attended) awareness perception of phantom sound is essential in activating the cognitive-emotional value. The cognitive-emotional value plays a crucial role in governing attention allocation as well as developing annoyance within tinnitus clinical distress. Structurally, the Neurofunctional Tinnitus Model includes the peripheral auditory system, the thalamus, the limbic system, brainstem, basal ganglia, striatum, and the auditory along with prefrontal cortices. Functionally, we assume the model includes presence of continuous or intermittent abnormal signals at the peripheral auditory system or midbrain auditory paths. Depending on the availability of attentional resources, the signals may or may not be perceived. The cognitive valuation process strengthens the lateral-inhibition and noise canceling mechanisms in the mid-brain, which leads to the cessation of sound perception and renders the signal evaluation irrelevant. However, the “sourceless” sound is eventually perceived and can be cognitively interpreted as suspicious or an indication of a disease in which the cortical top-down processes weaken the noise canceling effects. This results in an increase in cognitive and emotional negative reactions such as depression and anxiety. The negative or positive cognitive-emotional feedbacks within the top-down approach may have no relation to the previous experience of the patients. They can also be

  9. Voronoi cell patterns: Theoretical model and applications

    NASA Astrophysics Data System (ADS)

    González, Diego Luis; Einstein, T. L.

    2011-11-01

    We use a simple fragmentation model to describe the statistical behavior of the Voronoi cell patterns generated by a homogeneous and isotropic set of points in 1D and in 2D. In particular, we are interested in the distribution of sizes of these Voronoi cells. Our model is completely defined by two probability distributions in 1D and again in 2D, the probability to add a new point inside an existing cell and the probability that this new point is at a particular position relative to the preexisting point inside this cell. In 1D the first distribution depends on a single parameter while the second distribution is defined through a fragmentation kernel; in 2D both distributions depend on a single parameter. The fragmentation kernel and the control parameters are closely related to the physical properties of the specific system under study. We use our model to describe the Voronoi cell patterns of several systems. Specifically, we study the island nucleation with irreversible attachment, the 1D car-parking problem, the formation of second-level administrative divisions, and the pattern formed by the Paris Métro stations.

  10. Hybrid E-Learning Acceptance Model: Learner Perceptions

    ERIC Educational Resources Information Center

    Ahmed, Hassan M. Selim

    2010-01-01

    E-learning tools and technologies have been used to supplement conventional courses in higher education institutions creating a "hybrid" e-learning module that aims to enhance the learning experiences of students. Few studies have addressed the acceptance of hybrid e-learning by learners and the factors affecting the learners'…

  11. Theoretical Modelling of Synthetic Molecular Motors

    NASA Astrophysics Data System (ADS)

    Barbu, Corina; Sofo, Jorge; Crespi, Vincent

    2004-03-01

    Synthetic molecular motors with sizes of few nanometers offer prospects to control molecular-scale mechanical motion. Motors with electric dipoles designed into their structure can undergo conformational changes in response to an external electric field and thereby, in principle, perform mechanical work. The synthetic rotary motor of our interest consists of a molecular caltrop with a three-legged base for attachment to a substrate and a molecular shaft functionalized with a molecular rotor at the upper end. Both the static dipole and the electric field-induced dipole of the molecular rotor are relevant to producing rotation. Also, the combination of external electrostatic torque and the internal thermal fluctuations must be sufficient to overcome any rotational barriers on experimentally relevant timescales. Density functional theory calculations at the B3LYP/TZV level coupled to analytical modelling reveal the dynamical response of the motor.

  12. Theoretical model for plasma opening switch

    SciTech Connect

    Baker, L.

    1980-07-01

    The theory of an explosive plasma switch is developed and compared with the experimental results of Pavlovskii and work at Sandia. A simple analytic model is developed, which predicts that such switches may achieve opening times of approximately 100 ns. When the switching time is limited by channel mixing it scales as t = C(m d/sub 0/)/sup 1/2/P/sub 0//sup 2/P/sub e//sup -5/2/ where m is the foil mass per unit area, d/sub 0/ the channel thickness and P/sub 0/ the channel pressure (at explosive breakout), P/sub e/ the explosive pressure, C a constant of order 10 for c.g.s. units. Thus faster switching times may be achieved by minimizing foil mass and channel pressure, or increasing explosive product pressure, with the scaling exponents as shown suggesting that changes in pressures would be more effective.

  13. Dynamics in Higher Education Politics: A Theoretical Model

    ERIC Educational Resources Information Center

    Kauko, Jaakko

    2013-01-01

    This article presents a model for analysing dynamics in higher education politics (DHEP). Theoretically the model draws on the conceptual history of political contingency, agenda-setting theories and previous research on higher education dynamics. According to the model, socio-historical complexity can best be analysed along two dimensions: the…

  14. Development of a Health Information Technology Acceptance Model Using Consumers’ Health Behavior Intention

    PubMed Central

    2012-01-01

    Background For effective health promotion using health information technology (HIT), it is mandatory that health consumers have the behavioral intention to measure, store, and manage their own health data. Understanding health consumers’ intention and behavior is needed to develop and implement effective and efficient strategies. Objective To develop and verify the extended Technology Acceptance Model (TAM) in health care by describing health consumers’ behavioral intention of using HIT. Methods This study used a cross-sectional descriptive correlational design. We extended TAM by adding more antecedents and mediating variables to enhance the model’s explanatory power and to make it more applicable to health consumers’ behavioral intention. Additional antecedents and mediating variables were added to the hypothetical model, based on their theoretical relevance, from the Health Belief Model and theory of planned behavior, along with the TAM. We undertook structural equation analysis to examine the specific nature of the relationship involved in understanding consumers’ use of HIT. Study participants were 728 members recruited from three Internet health portals in Korea. Data were collected by a Web-based survey using a structured self-administered questionnaire. Results The overall fitness indices for the model developed in this study indicated an acceptable fit of the model. All path coefficients were statistically significant. This study showed that perceived threat, perceived usefulness, and perceived ease of use significantly affected health consumers’ attitude and behavioral intention. Health consumers’ health status, health belief and concerns, subjective norm, HIT characteristics, and HIT self-efficacy had a strong indirect impact on attitude and behavioral intention through the mediators of perceived threat, perceived usefulness, and perceived ease of use. Conclusions An extended TAM in the HIT arena was found to be valid to describe health

  15. Testing a Theoretical Model of Immigration Transition and Physical Activity.

    PubMed

    Chang, Sun Ju; Im, Eun-Ok

    2015-01-01

    The purposes of the study were to develop a theoretical model to explain the relationships between immigration transition and midlife women's physical activity and test the relationships among the major variables of the model. A theoretical model, which was developed based on transitions theory and the midlife women's attitudes toward physical activity theory, consists of 4 major variables, including length of stay in the United States, country of birth, level of acculturation, and midlife women's physical activity. To test the theoretical model, a secondary analysis with data from 127 Hispanic women and 123 non-Hispanic (NH) Asian women in a national Internet study was used. Among the major variables of the model, length of stay in the United States was negatively associated with physical activity in Hispanic women. Level of acculturation in NH Asian women was positively correlated with women's physical activity. Country of birth and level of acculturation were significant factors that influenced physical activity in both Hispanic and NH Asian women. The findings support the theoretical model that was developed to examine relationships between immigration transition and physical activity; it shows that immigration transition can play an essential role in influencing health behaviors of immigrant populations in the United States. The NH theoretical model can be widely used in nursing practice and research that focus on immigrant women and their health behaviors. Health care providers need to consider the influences of immigration transition to promote immigrant women's physical activity. PMID:26502554

  16. Testing a Theoretical Model of Immigration Transition and Physical Activity.

    PubMed

    Chang, Sun Ju; Im, Eun-Ok

    2015-01-01

    The purposes of the study were to develop a theoretical model to explain the relationships between immigration transition and midlife women's physical activity and test the relationships among the major variables of the model. A theoretical model, which was developed based on transitions theory and the midlife women's attitudes toward physical activity theory, consists of 4 major variables, including length of stay in the United States, country of birth, level of acculturation, and midlife women's physical activity. To test the theoretical model, a secondary analysis with data from 127 Hispanic women and 123 non-Hispanic (NH) Asian women in a national Internet study was used. Among the major variables of the model, length of stay in the United States was negatively associated with physical activity in Hispanic women. Level of acculturation in NH Asian women was positively correlated with women's physical activity. Country of birth and level of acculturation were significant factors that influenced physical activity in both Hispanic and NH Asian women. The findings support the theoretical model that was developed to examine relationships between immigration transition and physical activity; it shows that immigration transition can play an essential role in influencing health behaviors of immigrant populations in the United States. The NH theoretical model can be widely used in nursing practice and research that focus on immigrant women and their health behaviors. Health care providers need to consider the influences of immigration transition to promote immigrant women's physical activity.

  17. Acceptance and Commitment Therapy as a Unified Model of Behavior Change

    ERIC Educational Resources Information Center

    Hayes, Steven C.; Pistorello, Jacqueline; Levin, Michael E.

    2012-01-01

    The present article summarizes the assumptions, model, techniques, evidence, and diversity/social justice commitments of Acceptance and Commitment Therapy (ACT). ACT focused on six processes (acceptance, defusion, self, now, values, and action) that bear on a single overall target (psychological flexibility). The ACT model of behavior change has…

  18. Applying the Technology Acceptance Model and flow theory to Cyworld user behavior: implication of the Web2.0 user acceptance.

    PubMed

    Shin, Dong-Hee; Kim, Won-Yong; Kim, Won-Young

    2008-06-01

    This study explores attitudinal and behavioral patterns when using Cyworld by adopting an expanded Technology Acceptance Model (TAM). A model for Cyworld acceptance is used to examine how various factors modified from the TAM influence acceptance and its antecedents. This model is examined through an empirical study involving Cyworld users using structural equation modeling techniques. The model shows reasonably good measurement properties and the constructs are validated. The results not only confirm the model but also reveal general factors applicable to Web2.0. A set of constructs in the model can be the Web2.0-specific factors, playing as enhancing factor to attitudes and intention.

  19. Culture and Developmental Trajectories: A Discussion on Contemporary Theoretical Models

    ERIC Educational Resources Information Center

    de Carvalho, Rafael Vera Cruz; Seidl-de-Moura, Maria Lucia; Martins, Gabriela Dal Forno; Vieira, Mauro Luís

    2014-01-01

    This paper aims to describe, compare and discuss the theoretical models proposed by Patricia Greenfield, Çigdem Kagitçibasi and Heidi Keller. Their models have the common goal of understanding the developmental trajectories of self based on dimensions of autonomy and relatedness that are structured according to specific cultural and environmental…

  20. Organizational Learning and Product Design Management: Towards a Theoretical Model.

    ERIC Educational Resources Information Center

    Chiva-Gomez, Ricardo; Camison-Zornoza, Cesar; Lapiedra-Alcami, Rafael

    2003-01-01

    Case studies of four Spanish ceramics companies were used to construct a theoretical model of 14 factors essential to organizational learning. One set of factors is related to the conceptual-analytical phase of the product design process and the other to the creative-technical phase. All factors contributed to efficient product design management…

  1. Healing from Childhood Sexual Abuse: A Theoretical Model

    ERIC Educational Resources Information Center

    Draucker, Claire Burke; Martsolf, Donna S.; Roller, Cynthia; Knapik, Gregory; Ross, Ratchneewan; Stidham, Andrea Warner

    2011-01-01

    Childhood sexual abuse is a prevalent social and health care problem. The processes by which individuals heal from childhood sexual abuse are not clearly understood. The purpose of this study was to develop a theoretical model to describe how adults heal from childhood sexual abuse. Community recruitment for an ongoing broader project on sexual…

  2. The Theoretical Basis of the Effective School Improvement Model (ESI)

    ERIC Educational Resources Information Center

    Scheerens, Jaap; Demeuse, Marc

    2005-01-01

    This article describes the process of theoretical reflection that preceded the development and empirical verification of a model of "effective school improvement". The focus is on basic mechanisms that could be seen as underlying "getting things in motion" and change in education systems. Four mechanisms are distinguished: synoptic rational…

  3. Integrating social capital theory, social cognitive theory, and the technology acceptance model to explore a behavioral model of telehealth systems.

    PubMed

    Tsai, Chung-Hung

    2014-05-01

    Telehealth has become an increasingly applied solution to delivering health care to rural and underserved areas by remote health care professionals. This study integrated social capital theory, social cognitive theory, and the technology acceptance model (TAM) to develop a comprehensive behavioral model for analyzing the relationships among social capital factors (social capital theory), technological factors (TAM), and system self-efficacy (social cognitive theory) in telehealth. The proposed framework was validated with 365 respondents from Nantou County, located in Central Taiwan. Structural equation modeling (SEM) was used to assess the causal relationships that were hypothesized in the proposed model. The finding indicates that elderly residents generally reported positive perceptions toward the telehealth system. Generally, the findings show that social capital factors (social trust, institutional trust, and social participation) significantly positively affect the technological factors (perceived ease of use and perceived usefulness respectively), which influenced usage intention. This study also confirmed that system self-efficacy was the salient antecedent of perceived ease of use. In addition, regarding the samples, the proposed model fitted considerably well. The proposed integrative psychosocial-technological model may serve as a theoretical basis for future research and can also offer empirical foresight to practitioners and researchers in the health departments of governments, hospitals, and rural communities. PMID:24810577

  4. Integrating Social Capital Theory, Social Cognitive Theory, and the Technology Acceptance Model to Explore a Behavioral Model of Telehealth Systems

    PubMed Central

    Tsai, Chung-Hung

    2014-01-01

    Telehealth has become an increasingly applied solution to delivering health care to rural and underserved areas by remote health care professionals. This study integrated social capital theory, social cognitive theory, and the technology acceptance model (TAM) to develop a comprehensive behavioral model for analyzing the relationships among social capital factors (social capital theory), technological factors (TAM), and system self-efficacy (social cognitive theory) in telehealth. The proposed framework was validated with 365 respondents from Nantou County, located in Central Taiwan. Structural equation modeling (SEM) was used to assess the causal relationships that were hypothesized in the proposed model. The finding indicates that elderly residents generally reported positive perceptions toward the telehealth system. Generally, the findings show that social capital factors (social trust, institutional trust, and social participation) significantly positively affect the technological factors (perceived ease of use and perceived usefulness respectively), which influenced usage intention. This study also confirmed that system self-efficacy was the salient antecedent of perceived ease of use. In addition, regarding the samples, the proposed model fitted considerably well. The proposed integrative psychosocial-technological model may serve as a theoretical basis for future research and can also offer empirical foresight to practitioners and researchers in the health departments of governments, hospitals, and rural communities. PMID:24810577

  5. Integrating social capital theory, social cognitive theory, and the technology acceptance model to explore a behavioral model of telehealth systems.

    PubMed

    Tsai, Chung-Hung

    2014-05-07

    Telehealth has become an increasingly applied solution to delivering health care to rural and underserved areas by remote health care professionals. This study integrated social capital theory, social cognitive theory, and the technology acceptance model (TAM) to develop a comprehensive behavioral model for analyzing the relationships among social capital factors (social capital theory), technological factors (TAM), and system self-efficacy (social cognitive theory) in telehealth. The proposed framework was validated with 365 respondents from Nantou County, located in Central Taiwan. Structural equation modeling (SEM) was used to assess the causal relationships that were hypothesized in the proposed model. The finding indicates that elderly residents generally reported positive perceptions toward the telehealth system. Generally, the findings show that social capital factors (social trust, institutional trust, and social participation) significantly positively affect the technological factors (perceived ease of use and perceived usefulness respectively), which influenced usage intention. This study also confirmed that system self-efficacy was the salient antecedent of perceived ease of use. In addition, regarding the samples, the proposed model fitted considerably well. The proposed integrative psychosocial-technological model may serve as a theoretical basis for future research and can also offer empirical foresight to practitioners and researchers in the health departments of governments, hospitals, and rural communities.

  6. A Generalized Information Theoretical Model for Quantum Secret Sharing

    NASA Astrophysics Data System (ADS)

    Bai, Chen-Ming; Li, Zhi-Hui; Xu, Ting-Ting; Li, Yong-Ming

    2016-07-01

    An information theoretical model for quantum secret sharing was introduced by H. Imai et al. (Quantum Inf. Comput. 5(1), 69-80 2005), which was analyzed by quantum information theory. In this paper, we analyze this information theoretical model using the properties of the quantum access structure. By the analysis we propose a generalized model definition for the quantum secret sharing schemes. In our model, there are more quantum access structures which can be realized by our generalized quantum secret sharing schemes than those of the previous one. In addition, we also analyse two kinds of important quantum access structures to illustrate the existence and rationality for the generalized quantum secret sharing schemes and consider the security of the scheme by simple examples.

  7. A theoretical model for smoking prevention studies in preteen children.

    PubMed

    McGahee, T W; Kemp, V; Tingen, M

    2000-01-01

    The age of the onset of smoking is on a continual decline, with the prime age of tobacco use initiation being 12-14 years. A weakness of the limited research conducted on smoking prevention programs designed for preteen children (ages 10-12) is a well-defined theoretical basis. A theoretical perspective is needed in order to make a meaningful transition from empirical analysis to application of knowledge. Bandura's Social Cognitive Theory (1977, 1986), the Theory of Reasoned Action (Ajzen & Fishbein, 1980), and other literature linking various concepts to smoking behaviors in preteens were used to develop a model that may be useful for smoking prevention studies in preteen children.

  8. Modelling acceptance of sunlight in high and low photovoltaic concentration

    SciTech Connect

    Leutz, Ralf

    2014-09-26

    A simple model incorporating linear radiation characteristics, along with the optical trains and geometrical concentration ratios of solar concentrators is presented with performance examples for optical trains of HCPV, LCPV and benchmark flat-plate PV.

  9. Electromechanical properties of smart aggregate: theoretical modeling and experimental validation

    NASA Astrophysics Data System (ADS)

    Wang, Jianjun; Kong, Qingzhao; Shi, Zhifei; Song, Gangbing

    2016-09-01

    Smart aggregate (SA), as a piezoceramic-based multi-functional device, is formed by sandwiching two lead zirconate titanate (PZT) patches with copper shielding between a pair of solid-machined cylindrical marble blocks with epoxy. Previous researches have successfully demonstrated the capability and reliability of versatile SAs to monitor the structural health of concrete structures. However, the previous works concentrated mainly on the applications of SAs in structural health monitoring; no reasonable theoretical model of SAs was proposed. In this paper, electromechanical properties of SAs were investigated using a proposed theoretical model. Based on one dimensional linear theory of piezo-elasticity, the dynamic solutions of a SA subjected to an external harmonic voltage were solved. Further, the electric impedance of the SA was computed, and the resonance and anti-resonance frequencies were calculated based on derived equations. Numerical analysis was conducted to discuss the effects of the thickness of epoxy layer and the dimension of PZT patch on the fundamental resonance and anti-resonance frequencies as well as the corresponding electromechanical coupling factor. The dynamic solutions based on the proposed theoretical model were further experimentally verified with two SA samples. The fundamental resonance and anti-resonance frequencies of SAs show good agreements in both theoretical and experimental results. The presented analysis and results contribute to the overall understanding of SA properties and help to optimize the working frequencies of SAs in structural health monitoring of civil structures.

  10. Theoretical determination of the neuron detection efficiency of plastic track detectors. I. Theoretical model

    NASA Astrophysics Data System (ADS)

    Pretzsch, Gunter

    A theoretical model to determine the neutron detection efficiency of organic solid state nuclear track detectors without external radiator is described. The model involves the following calculation steps: production of heavy charged particles within the detector volume, characterization of the charged particles by appropriate physical quantities, application of suitable registration criteria, formation of etch pits. The etch pits formed are described by means of a distribution function which is doubly differential in both diameter and depth of the etch pits. The distribution function serves as the input value for the calculation of the detection efficiency. The detection efficiency is defined as the measured effect per neutron fluence. Hence it depends on the evaluation technique considered. The calculation of the distribution function is carried out for cellulose triacetate. The determination of the concrete detection efficiency using the light microscope and light transmission measurements as the evaluation technique will be described in further publications.

  11. Theoretical model of infrared radiation of dressed human body indoors

    NASA Astrophysics Data System (ADS)

    Xiong, Zonglong; Yang, Kuntao

    2008-02-01

    The human body detecting by infrared thermography plays an important role in the field of medical treatment, scout and rescuing work after disaster occuring. The infrared image theoretical model is a foundation for a human body detecting because it can improve the ability and efficiency. The essence and significance of the information on the temperature field of the human body in indoor environment is systematically discussed on the basis of physical structure and thermoregulation system. The various factors that influence the body temperature are analyzed, then the method for the calculation of temperature distribution of the surface temperature is introduced. On the basis of the infrared radiation theory, a theoretical model is proposed to calculate the radiant flux intensity of the human body. This model can be applied to many fields.

  12. Theoretical modeling of critical temperature increase in metamaterial superconductors

    NASA Astrophysics Data System (ADS)

    Smolyaninov, Igor I.; Smolyaninova, Vera N.

    2016-05-01

    Recent experiments have demonstrated that the metamaterial approach is capable of a drastic increase of the critical temperature Tc of epsilon near zero (ENZ) metamaterial superconductors. For example, tripling of the critical temperature has been observed in Al -A l2O3 ENZ core-shell metamaterials. Here, we perform theoretical modeling of Tc increase in metamaterial superconductors based on the Maxwell-Garnett approximation of their dielectric response function. Good agreement is demonstrated between theoretical modeling and experimental results in both aluminum- and tin-based metamaterials. Taking advantage of the demonstrated success of this model, the critical temperature of hypothetic niobium-, Mg B2- , and H2S -based metamaterial superconductors is evaluated. The Mg B2 -based metamaterial superconductors are projected to reach the liquid nitrogen temperature range. In the case of a H2S -based metamaterial Tc appears to reach ˜250 K.

  13. Family support and acceptance, gay male identity formation, and psychological adjustment: a path model.

    PubMed

    Elizur, Y; Ziv, M

    2001-01-01

    While heterosexist family undermining has been demonstrated to be a developmental risk factor in the life of persons with same-gender orientation, the issue of protective family factors is both controversial and relatively neglected. In this study of Israeli gay males (N = 114), we focused on the interrelations of family support, family acceptance and family knowledge of gay orientation, and gay male identity formation, and their effects on mental health and self-esteem. A path model was proposed based on the hypotheses that family support, family acceptance, family knowledge, and gay identity formation have an impact on psychological adjustment, and that family support has an effect on gay identity formation that is mediated by family acceptance. The assessment of gay identity formation was based on an established stage model that was streamlined for cross-cultural practice by defining three basic processes of same-gender identity formation: self-definition, self-acceptance, and disclosure (Elizur & Mintzer, 2001). The testing of our conceptual path model demonstrated an excellent fit with the data. An alternative model that hypothesized effects of gay male identity on family acceptance and family knowledge did not fit the data. Interpreting these results, we propose that the main effect of family support/acceptance on gay identity is related to the process of disclosure, and that both general family support and family acceptance of same-gender orientation play a significant role in the psychological adjustment of gay men.

  14. 24 CFR 200.926c - Model code provisions for use in partially accepted code jurisdictions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 24 Housing and Urban Development 2 2011-04-01 2011-04-01 false Model code provisions for use in... Minimum Property Standards § 200.926c Model code provisions for use in partially accepted code..., those portions of one of the model codes with which the property must comply. Schedule for Model...

  15. Theoretical models of efficiency for polycrystalline thin film solar cells. Final report, September 1, 1979-January 31, 1981

    SciTech Connect

    Not Available

    1981-02-01

    The literature on Schottky and MIS diodes was thoroughly reviewed. Underlying the accepted theoretical models for MIS devices, a major weakness in the handling of current flow through the insulating layer was identified. An alternative model based on pinholes in the insulating layer was proposed. Parametric analysis of Zn/sub 3/P/sub 2/ homojunctions and ZnO/Zn/sub 3/P/sub 2/ heterojunctions was done and limits of efficiency were calculated.

  16. Adolescents' unconditional acceptance by parents and teachers and educational outcomes: A structural model of gender differences.

    PubMed

    Makri-Botsari, Evi

    2015-08-01

    The purpose of this study was to detect gender specific patterns in the network of relations between unconditionality of parental and teacher acceptance in the form of unconditional positive regard and a range of educational outcomes, as indexed by academic self-perception, academic intrinsic motivation, and academic achievement. To test the role of gender as a moderator, a multi-group analysis was employed within the framework of structural equation modelling with increasing restrictions placed on the structural paths across genders. The results on a sample of 427 adolescents in grades 7-9 showed that conditionality of acceptance undermined level of perceived acceptance for both social agents. Moreover, unconditionality of teacher acceptance exerted stronger influences on students' educational outcomes than unconditionality of parental acceptance, with effect sizes being larger for girls than for boys. PMID:26057875

  17. Adolescents' unconditional acceptance by parents and teachers and educational outcomes: A structural model of gender differences.

    PubMed

    Makri-Botsari, Evi

    2015-08-01

    The purpose of this study was to detect gender specific patterns in the network of relations between unconditionality of parental and teacher acceptance in the form of unconditional positive regard and a range of educational outcomes, as indexed by academic self-perception, academic intrinsic motivation, and academic achievement. To test the role of gender as a moderator, a multi-group analysis was employed within the framework of structural equation modelling with increasing restrictions placed on the structural paths across genders. The results on a sample of 427 adolescents in grades 7-9 showed that conditionality of acceptance undermined level of perceived acceptance for both social agents. Moreover, unconditionality of teacher acceptance exerted stronger influences on students' educational outcomes than unconditionality of parental acceptance, with effect sizes being larger for girls than for boys.

  18. Theory development in health care informatics: Information and communication technology acceptance model (ICTAM) improves the explanatory and predictive power of technology acceptance models.

    PubMed

    An, Ji-Young

    2006-01-01

    The purpose of this web-based study was to explain and predict consumers' acceptance and usage behavior of Internet health information and services. Toward this goal, the Information and Communication Technology Acceptance Model (ICTAM) was developed and tested. Individuals who received a flyer through the LISTSERV of HealthGuide were eligible to participate. The study population was eighteen years old and older who had used Internet health information and services for a minimum of 6 months. For the analyses, SPSS (version 13.0) and AMOS (version 5.0) were employed. More than half of the respondents were women (n = 110, 55%). The average age of the respondents was 35.16 years (S.D. = 10.07). A majority reported at least some college education (n = 126, 63%). All of the observed factors accounted for 75.53% of the total variance explained. The fit indices of the structural model were within an acceptable range: chi2/df = 2.38 (chi2 = 1786.31, df = 752); GFI = .71; RMSEA = .08; CFI = .86; NFI = .78. The results of this study provide empirical support for the continued development of ICTAM in the area of health consumers' information and communication technology acceptance.

  19. Predicting nurses' use of healthcare technology using the technology acceptance model: an integrative review.

    PubMed

    Strudwick, Gillian

    2015-05-01

    The benefits of healthcare technologies can only be attained if nurses accept and intend to fully use them. One of the most common models utilized to understand user acceptance of technology is the Technology Acceptance Model. This model and modified versions of it have only recently been applied in the healthcare literature among nurse participants. An integrative literature review was conducted on this topic. Ovid/MEDLINE, PubMed, Google Scholar, and CINAHL were searched yielding a total of 982 references. Upon eliminating duplicates and applying the inclusion and exclusion criteria, the review included a total of four dissertations, three symposium proceedings, and 13 peer-reviewed journal articles. These documents were appraised and reviewed. The results show that a modified Technology Acceptance Model with added variables could provide a better explanation of nurses' acceptance of healthcare technology. These added variables to modified versions of the Technology Acceptance Model are discussed, and the studies' methodologies are critiqued. Limitations of the studies included in the integrative review are also examined.

  20. Modeling nurses' attitude toward using automated unit-based medication storage and distribution systems: an extension of the technology acceptance model.

    PubMed

    Escobar-Rodríguez, Tomás; Romero-Alonso, María Mercedes

    2013-05-01

    This article analyzes the attitude of nurses toward the use of automated unit-based medication storage and distribution systems and identifies influencing factors. Understanding these factors provides an opportunity to explore actions that might be taken to boost adoption by potential users. The theoretical grounding for this research is the Technology Acceptance Model. The Technology Acceptance Model specifies the causal relationships between perceived usefulness, perceived ease of use, attitude toward using, and actual usage behavior. The research model has six constructs, and nine hypotheses were generated from connections between these six constructs. These constructs include perceived risks, experience level, and training. The findings indicate that these three external variables are related to the perceived ease of use and perceived usefulness of automated unit-based medication storage and distribution systems, and therefore, they have a significant influence on attitude toward the use of these systems.

  1. A Multivariate Model for the Study of Parental Acceptance-Rejection and Child Abuse.

    ERIC Educational Resources Information Center

    Rohner, Ronald P.; Rohner, Evelyn C.

    This paper proposes a multivariate strategy for the study of parental acceptance-rejection and child abuse and describes a research study on parental rejection and child abuse which illustrates the advantages of using a multivariate, (rather than a simple-model) approach. The multivariate model is a combination of three simple models used to study…

  2. A proposed model of factors influencing hydrogen fuel cell vehicle acceptance

    NASA Astrophysics Data System (ADS)

    Imanina, N. H. Noor; Kwe Lu, Tan; Fadhilah, A. R.

    2016-03-01

    Issues such as environmental problem and energy insecurity keep worsening as a result of energy use from household to huge industries including automotive industry. Recently, a new type of zero emission vehicle, hydrogen fuel cell vehicle (HFCV) has received attention. Although there are argues on the feasibility of hydrogen as the future fuel, there is another important issue, which is the acceptance of HFCV. The study of technology acceptance in the early stage is a vital key for a successful introduction and penetration of a technology. This paper proposes a model of factors influencing green vehicle acceptance, specifically HFCV. This model is built base on two technology acceptance theories and other empirical studies of vehicle acceptance. It aims to provide a base for finding the key factors influencing new sustainable energy fuelled vehicle, HFCV acceptance which is achieved by explaining intention to accept HFCV. Intention is influenced by attitude, subjective norm and perceived behavioural control from Theory of Planned Behaviour and personal norm from Norm Activation Theory. In the framework, attitude is influenced by perceptions of benefits and risks, and social trust. Perceived behavioural control is influenced by government interventions. Personal norm is influenced by outcome efficacy and problem awareness.

  3. Test of the technology acceptance model for the internet in pediatrics.

    PubMed Central

    Chismar, William G.; Wiley-Patton, Sonja

    2002-01-01

    There is growing recognition of the importance of the Internet and, more generally, information technology to pediatric care. However, acceptance of these technologies has been low. Attitudes of physicians can play a pivotal role in the adoption session. This study tests the extension to a widely used model in the information systems literature: the Technology Acceptance Model (TAM). Data were collected in a survey of pediatricians to see how well the extended model, TAM2, fits in the medical arena. Our results partially confirm the model; significant parts of the model were not confirmed. The primary factors in pediatricians' acceptance of technology applications relate to their usefulness and job relevance. Little weight is given to ease of use and social factors. We discuss possible explanations for the discrepancies and suggest future research. PMID:12463806

  4. A theoretical model for smoking prevention studies in preteen children.

    PubMed

    McGahee, T W; Kemp, V; Tingen, M

    2000-01-01

    The age of the onset of smoking is on a continual decline, with the prime age of tobacco use initiation being 12-14 years. A weakness of the limited research conducted on smoking prevention programs designed for preteen children (ages 10-12) is a well-defined theoretical basis. A theoretical perspective is needed in order to make a meaningful transition from empirical analysis to application of knowledge. Bandura's Social Cognitive Theory (1977, 1986), the Theory of Reasoned Action (Ajzen & Fishbein, 1980), and other literature linking various concepts to smoking behaviors in preteens were used to develop a model that may be useful for smoking prevention studies in preteen children. PMID:12026266

  5. Theoretical model for plasma expansion generated by hypervelocity impact

    SciTech Connect

    Ju, Yuanyuan; Zhang, Qingming Zhang, Dongjiang; Long, Renrong; Chen, Li; Huang, Fenglei; Gong, Zizheng

    2014-09-15

    The hypervelocity impact experiments of spherical LY12 aluminum projectile diameter of 6.4 mm on LY12 aluminum target thickness of 23 mm have been conducted using a two-stage light gas gun. The impact velocity of the projectile is 5.2, 5.7, and 6.3 km/s, respectively. The experimental results show that the plasma phase transition appears under the current experiment conditions, and the plasma expansion consists of accumulation, equilibrium, and attenuation. The plasma characteristic parameters decrease as the plasma expands outward and are proportional with the third power of the impact velocity, i.e., (T{sub e}, n{sub e}) ∝ v{sub p}{sup 3}. Based on the experimental results, a theoretical model on the plasma expansion is developed and the theoretical results are consistent with the experimental data.

  6. A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids

    PubMed Central

    Dai, Fu-Zhi; Zhou, Yanchun

    2016-01-01

    Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials. PMID:27604165

  7. A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids

    NASA Astrophysics Data System (ADS)

    Dai, Fu-Zhi; Zhou, Yanchun

    2016-09-01

    Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials.

  8. A Modified Theoretical Model of Intrinsic Hardness of Crystalline Solids.

    PubMed

    Dai, Fu-Zhi; Zhou, Yanchun

    2016-01-01

    Super-hard materials have been extensively investigated due to their practical importance in numerous industrial applications. To stimulate the design and exploration of new super-hard materials, microscopic models that elucidate the fundamental factors controlling hardness are desirable. The present work modified the theoretical model of intrinsic hardness proposed by Gao. In the modification, we emphasize the critical role of appropriately decomposing a crystal to pseudo-binary crystals, which should be carried out based on the valence electron population of each bond. After modification, the model becomes self-consistent and predicts well the hardness values of many crystals, including crystals composed of complex chemical bonds. The modified model provides fundamental insights into the nature of hardness, which can facilitate the quest for intrinsic super-hard materials. PMID:27604165

  9. Healing from Childhood Sexual Abuse: A Theoretical Model

    PubMed Central

    Draucker, Claire Burke; Martsolf, Donna S.; Roller, Cynthia; Knapik, Gregory; Ross, Ratchneewan; Stidham, Andrea Warner

    2014-01-01

    Childhood sexual abuse (CSA) is a prevalent social and healthcare problem. The processes by which individuals heal from CSA are not clearly understood. The purpose of this study was to develop a theoretical model to describe how adults heal from CSA. Community recruitment for an on-going, broader project on sexual violence throughout the lifespan, referred to as the Sexual Violence Study, yielded a subsample of 48 women and 47 men who had experienced CSA. During semi-structured, open-ended interviews, they were asked to describe their experiences with healing from CSA and other victimization throughout their lives. Constructivist grounded theory methods were used with these data to develop constructs and hypotheses about healing. For the Sexual Violence Study, frameworks were developed to describe the participants' life patterns, parenting experiences, disclosures about sexual violence, spirituality, and altruism. Several analytic techniques were used to synthesize the findings of these frameworks to develop an overarching theoretical model that describes healing from CSA. The model includes four stages of healing, five domains of functioning, and six enabling factors that facilitate movement from one stage to the next. The findings indicate that healing is a complex and dynamic trajectory. The model can be used to alert clinicians to a variety of processes and enabling factors that facilitate healing in several domains and to guide discussions on important issues related to healing from CSA. PMID:21812546

  10. Theoretical consideration of a microcontinuum model of graphene

    NASA Astrophysics Data System (ADS)

    Yang, Gang; Huang, Zaixing; Gao, Cun-Fa; Zhang, Bin

    2016-05-01

    A microcontinuum model of graphene is proposed based on micromorphic theory, in which the planar Bravais cell of graphene crystal is taken as the basal element of finite size. Governing equations including the macro-displacements and the micro-deformations of the basal element are modified and derived in global coordinates. Since independent freedom degrees of the basal element are closely related to the modes of phonon dispersions, the secular equations in micromorphic form are obtained by substituting the assumed harmonic wave equations into the governing equations, and simplified further according to the properties of phonon dispersion relations of two-dimensional (2D) crystals. Thus, the constitutive equations of the microcontinuum model are confirmed, in which the constitutive constants are determined by fitting the data of experimental and theoretical phonon dispersion relations in literature respectively. By employing the 2D microcontinuum model, we obtained sound velocities, Rayleigh velocity and elastic moduli of graphene, which show good agreements with available experimental or theoretical values, indicating that the current model would be another efficient and reliable methodology to study the mechanical behaviors of graphene.

  11. Game-Theoretic Models of Information Overload in Social Networks

    NASA Astrophysics Data System (ADS)

    Borgs, Christian; Chayes, Jennifer; Karrer, Brian; Meeder, Brendan; Ravi, R.; Reagans, Ray; Sayedi, Amin

    We study the effect of information overload on user engagement in an asymmetric social network like Twitter. We introduce simple game-theoretic models that capture rate competition between celebrities producing updates in such networks where users non-strategically choose a subset of celebrities to follow based on the utility derived from high quality updates as well as disutility derived from having to wade through too many updates. Our two variants model the two behaviors of users dropping some potential connections (followership model) or leaving the network altogether (engagement model). We show that under a simple formulation of celebrity rate competition, there is no pure strategy Nash equilibrium under the first model. We then identify special cases in both models when pure rate equilibria exist for the celebrities: For the followership model, we show existence of a pure rate equilibrium when there is a global ranking of the celebrities in terms of the quality of their updates to users. This result also generalizes to the case when there is a partial order consistent with all the linear orders of the celebrities based on their qualities to the users. Furthermore, these equilibria can be computed in polynomial time. For the engagement model, pure rate equilibria exist when all users are interested in the same number of celebrities, or when they are interested in at most two. Finally, we also give a finite though inefficient procedure to determine if pure equilibria exist in the general case of the followership model.

  12. Information-Theoretic Benchmarking of Land Surface Models

    NASA Astrophysics Data System (ADS)

    Nearing, Grey; Mocko, David; Kumar, Sujay; Peters-Lidard, Christa; Xia, Youlong

    2016-04-01

    Benchmarking is a type of model evaluation that compares model performance against a baseline metric that is derived, typically, from a different existing model. Statistical benchmarking was used to qualitatively show that land surface models do not fully utilize information in boundary conditions [1] several years before Gong et al [2] discovered the particular type of benchmark that makes it possible to *quantify* the amount of information lost by an incorrect or imperfect model structure. This theoretical development laid the foundation for a formal theory of model benchmarking [3]. We here extend that theory to separate uncertainty contributions from the three major components of dynamical systems models [4]: model structures, model parameters, and boundary conditions describe time-dependent details of each prediction scenario. The key to this new development is the use of large-sample [5] data sets that span multiple soil types, climates, and biomes, which allows us to segregate uncertainty due to parameters from the two other sources. The benefit of this approach for uncertainty quantification and segregation is that it does not rely on Bayesian priors (although it is strictly coherent with Bayes' theorem and with probability theory), and therefore the partitioning of uncertainty into different components is *not* dependent on any a priori assumptions. We apply this methodology to assess the information use efficiency of the four land surface models that comprise the North American Land Data Assimilation System (Noah, Mosaic, SAC-SMA, and VIC). Specifically, we looked at the ability of these models to estimate soil moisture and latent heat fluxes. We found that in the case of soil moisture, about 25% of net information loss was from boundary conditions, around 45% was from model parameters, and 30-40% was from the model structures. In the case of latent heat flux, boundary conditions contributed about 50% of net uncertainty, and model structures contributed

  13. Modeling the acceptance of clinical information systems among hospital medical staff: an extended TAM model.

    PubMed

    Melas, Christos D; Zampetakis, Leonidas A; Dimopoulou, Anastasia; Moustakis, Vassilis

    2011-08-01

    Recent empirical research has utilized the Technology Acceptance Model (TAM) to advance the understanding of doctors' and nurses' technology acceptance in the workplace. However, the majority of the reported studies are either qualitative in nature or use small convenience samples of medical staff. Additionally, in very few studies moderators are either used or assessed despite their importance in TAM based research. The present study focuses on the application of TAM in order to explain the intention to use clinical information systems, in a random sample of 604 medical staff (534 physicians) working in 14 hospitals in Greece. We introduce physicians' specialty as a moderator in TAM and test medical staff's information and communication technology (ICT) knowledge and ICT feature demands, as external variables. The results show that TAM predicts a substantial proportion of the intention to use clinical information systems. Findings make a contribution to the literature by replicating, explaining and advancing the TAM, whereas theory is benefited by the addition of external variables and medical specialty as a moderator. Recommendations for further research are discussed.

  14. Uncertainty in urban stormwater quality modelling: the effect of acceptability threshold in the GLUE methodology.

    PubMed

    Freni, Gabriele; Mannina, Giorgio; Viviani, Gaspare

    2008-04-01

    Uncertainty analysis in integrated urban drainage modelling is of growing importance in the field of water quality. However, only few studies deal with uncertainty quantification in urban drainage modelling; furthermore, the few existing studies mainly focus on quantitative sewer flow modelling rather than uncertainty in water quality aspects. In this context, the generalised likelihood uncertainty estimation (GLUE) methodology was applied for the evaluation of the uncertainty of an integrated urban drainage model and some of its subjective hypotheses have been explored. More specifically, the influence of the subjective choice of the acceptability threshold has been detected in order to gain insights regarding its effect on the model results. The model has been applied to the Savena case study (Bologna, Italy) where water quality and quantity data were available. The model results show a strong influence of the acceptability threshold selection and confirm the importance of modeller's experience in the application of GLUE uncertainty analysis.

  15. Theoretical models for coronary vascular biomechanics: Progress & challenges

    PubMed Central

    Waters, Sarah L.; Alastruey, Jordi; Beard, Daniel A.; Bovendeerd, Peter H.M.; Davies, Peter F.; Jayaraman, Girija; Jensen, Oliver E.; Lee, Jack; Parker, Kim H.; Popel, Aleksander S.; Secomb, Timothy W.; Siebes, Maria; Sherwin, Spencer J.; Shipley, Rebecca J.; Smith, Nicolas P.; van de Vosse, Frans N.

    2013-01-01

    A key aim of the cardiac Physiome Project is to develop theoretical models to simulate the functional behaviour of the heart under physiological and pathophysiological conditions. Heart function is critically dependent on the delivery of an adequate blood supply to the myocardium via the coronary vasculature. Key to this critical function of the coronary vasculature is system dynamics that emerge via the interactions of the numerous constituent components at a range of spatial and temporal scales. Here, we focus on several components for which theoretical approaches can be applied, including vascular structure and mechanics, blood flow and mass transport, flow regulation, angiogenesis and vascular remodelling, and vascular cellular mechanics. For each component, we summarise the current state of the art in model development, and discuss areas requiring further research. We highlight the major challenges associated with integrating the component models to develop a computational tool that can ultimately be used to simulate the responses of the coronary vascular system to changing demands and to diseases and therapies. PMID:21040741

  16. Self-Assembled Magnetic Surface Swimmers: Theoretical Model

    NASA Astrophysics Data System (ADS)

    Aranson, Igor; Belkin, Maxim; Snezhko, Alexey

    2009-03-01

    The mechanisms of self-propulsion of living microorganisms are a fascinating phenomenon attracting enormous attention in the physics community. A new type of self-assembled micro-swimmers, magnetic snakes, is an excellent tool to model locomotion in a simple table-top experiment. The snakes self-assemble from a dispersion of magnetic microparticles suspended on the liquid-air interface and subjected to an alternating magnetic field. Formation and dynamics of these swimmers are captured in the framework of theoretical model coupling paradigm equation for the amplitude of surface waves, conservation law for the density of particles, and the Navier-Stokes equation for hydrodynamic flows. The results of continuum modeling are supported by hybrid molecular dynamics simulations of magnetic particles floating on the surface of fluid.

  17. Extending the Technology Acceptance Model to Explore the Intention to Use Second Life for Enhancing Healthcare Education

    ERIC Educational Resources Information Center

    Chow, Meyrick; Herold, David Kurt; Choo, Tat-Ming; Chan, Kitty

    2012-01-01

    Learners need to have good reasons to engage and accept e-learning. They need to understand that unless they do, the outcomes will be less favourable. The technology acceptance model (TAM) is the most widely recognized model addressing why users accept or reject technology. This study describes the development and evaluation of a virtual…

  18. Theoretical Models and Operational Frameworks in Public Health Ethics

    PubMed Central

    Petrini, Carlo

    2010-01-01

    The article is divided into three sections: (i) an overview of the main ethical models in public health (theoretical foundations); (ii) a summary of several published frameworks for public health ethics (practical frameworks); and (iii) a few general remarks. Rather than maintaining the superiority of one position over the others, the main aim of the article is to summarize the basic approaches proposed thus far concerning the development of public health ethics by describing and comparing the various ideas in the literature. With this in mind, an extensive list of references is provided. PMID:20195441

  19. Theoretical models and operational frameworks in public health ethics.

    PubMed

    Petrini, Carlo

    2010-01-01

    The article is divided into three sections: (i) an overview of the main ethical models in public health (theoretical foundations); (ii) a summary of several published frameworks for public health ethics (practical frameworks); and (iii) a few general remarks. Rather than maintaining the superiority of one position over the others, the main aim of the article is to summarize the basic approaches proposed thus far concerning the development of public health ethics by describing and comparing the various ideas in the literature. With this in mind, an extensive list of references is provided.

  20. Theoretical Modeling of Mechanical-Electrical Coupling of Carbon Nanotubes

    SciTech Connect

    Lu, Jun-Qiang; Jiang, Hanqiang

    2008-01-01

    Carbon nanotubes have been studied extensively due to their unique properties, ranging from electrical, mechanical, optical, to thermal properties. The coupling between the electrical and mechanical properties of carbon nanotubes has emerged as a new field, which raises both interesting fundamental problems and huge application potentials. In this article, we will review our recently work on the theoretical modeling on mechanical-electrical coupling of carbon nanotubes subject to various loading conditions, including tension/compression, torsion, and squashing. Some related work by other groups will be also mentioned.

  1. Accuracy Analysis of a Box-wing Theoretical SRP Model

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoya; Hu, Xiaogong; Zhao, Qunhe; Guo, Rui

    2016-07-01

    For Beidou satellite navigation system (BDS) a high accuracy SRP model is necessary for high precise applications especially with Global BDS establishment in future. The BDS accuracy for broadcast ephemeris need be improved. So, a box-wing theoretical SRP model with fine structure and adding conical shadow factor of earth and moon were established. We verified this SRP model by the GPS Block IIF satellites. The calculation was done with the data of PRN 1, 24, 25, 27 satellites. The results show that the physical SRP model for POD and forecast for GPS IIF satellite has higher accuracy with respect to Bern empirical model. The 3D-RMS of orbit is about 20 centimeters. The POD accuracy for both models is similar but the prediction accuracy with the physical SRP model is more than doubled. We tested 1-day 3-day and 7-day orbit prediction. The longer is the prediction arc length, the more significant is the improvement. The orbit prediction accuracy with the physical SRP model for 1-day, 3-day and 7-day arc length are 0.4m, 2.0m, 10.0m respectively. But they are 0.9m, 5.5m and 30m with Bern empirical model respectively. We apply this means to the BDS and give out a SRP model for Beidou satellites. Then we test and verify the model with Beidou data of one month only for test. Initial results show the model is good but needs more data for verification and improvement. The orbit residual RMS is similar to that with our empirical force model which only estimate the force for along track, across track direction and y-bias. But the orbit overlap and SLR observation evaluation show some improvement. The remaining empirical force is reduced significantly for present Beidou constellation.

  2. Theoretical description of phase coexistence in model C60.

    PubMed

    Costa, D; Pellicane, G; Caccamo, C; Schöll-Paschinger, E; Kahl, G

    2003-08-01

    We have investigated the phase diagram of a pair interaction model of C60 fullerene [L. A. Girifalco, J. Phys. Chem. 96, 858 (1992)], in the framework provided by two integral equation theories of the liquid state, namely, the modified hypernetted chain (MHNC) implemented under a global thermodynamic consistency constraint, and the self-consistent Ornstein-Zernike approximation (SCOZA), and by a perturbation theory (PT) with various degrees of refinement, for the free energy of the solid phase. We present an extended assessment of such theories as set against a recent Monte Carlo study of the same model [D. Costa, G. Pellicane, C. Caccamo, and M. C. Abramo, J. Chem. Phys. 118, 304 (2003)]. We have compared the theoretical predictions with the corresponding simulation results for several thermodynamic properties such as the free energy, the pressure, and the internal energy. Then we have determined the phase diagram of the model, by using either the SCOZA, the MHNC, or the PT predictions for one of the coexisting phases, and the simulation data for the other phase, in order to separately ascertain the accuracy of each theory. It turns out that the overall appearance of the phase portrait is reproduced fairly well by all theories, with remarkable accuracy as for the melting line and the solid-vapor equilibrium. All theories show a more or less pronounced discrepancy with the simulated fluid-solid coexistence pressure, above the triple point. The MHNC and SCOZA results for the liquid-vapor coexistence, as well as for the corresponding critical points, are quite accurate; the SCOZA tends to underestimate the density corresponding to the freezing line. All results are discussed in terms of the basic assumptions underlying each theory. We have then selected the MHNC for the fluid and the first-order PT for the solid phase, as the most accurate tools to investigate the phase behavior of the model in terms of purely theoretical approaches. It emerges that the use of

  3. NMR relaxation induced by iron oxide particles: testing theoretical models

    NASA Astrophysics Data System (ADS)

    Gossuin, Y.; Orlando, T.; Basini, M.; Henrard, D.; Lascialfari, A.; Mattea, C.; Stapf, S.; Vuong, Q. L.

    2016-04-01

    Superparamagnetic iron oxide particles find their main application as contrast agents for cellular and molecular magnetic resonance imaging. The contrast they bring is due to the shortening of the transverse relaxation time T 2 of water protons. In order to understand their influence on proton relaxation, different theoretical relaxation models have been developed, each of them presenting a certain validity domain, which depends on the particle characteristics and proton dynamics. The validation of these models is crucial since they allow for predicting the ideal particle characteristics for obtaining the best contrast but also because the fitting of T 1 experimental data by the theory constitutes an interesting tool for the characterization of the nanoparticles. In this work, T 2 of suspensions of iron oxide particles in different solvents and at different temperatures, corresponding to different proton diffusion properties, were measured and were compared to the three main theoretical models (the motional averaging regime, the static dephasing regime, and the partial refocusing model) with good qualitative agreement. However, a real quantitative agreement was not observed, probably because of the complexity of these nanoparticulate systems. The Roch theory, developed in the motional averaging regime (MAR), was also successfully used to fit T 1 nuclear magnetic relaxation dispersion (NMRD) profiles, even outside the MAR validity range, and provided a good estimate of the particle size. On the other hand, the simultaneous fitting of T 1 and T 2 NMRD profiles by the theory was impossible, and this occurrence constitutes a clear limitation of the Roch model. Finally, the theory was shown to satisfactorily fit the deuterium T 1 NMRD profile of superparamagnetic particle suspensions in heavy water.

  4. NMR relaxation induced by iron oxide particles: testing theoretical models.

    PubMed

    Gossuin, Y; Orlando, T; Basini, M; Henrard, D; Lascialfari, A; Mattea, C; Stapf, S; Vuong, Q L

    2016-04-15

    Superparamagnetic iron oxide particles find their main application as contrast agents for cellular and molecular magnetic resonance imaging. The contrast they bring is due to the shortening of the transverse relaxation time T 2 of water protons. In order to understand their influence on proton relaxation, different theoretical relaxation models have been developed, each of them presenting a certain validity domain, which depends on the particle characteristics and proton dynamics. The validation of these models is crucial since they allow for predicting the ideal particle characteristics for obtaining the best contrast but also because the fitting of T 1 experimental data by the theory constitutes an interesting tool for the characterization of the nanoparticles. In this work, T 2 of suspensions of iron oxide particles in different solvents and at different temperatures, corresponding to different proton diffusion properties, were measured and were compared to the three main theoretical models (the motional averaging regime, the static dephasing regime, and the partial refocusing model) with good qualitative agreement. However, a real quantitative agreement was not observed, probably because of the complexity of these nanoparticulate systems. The Roch theory, developed in the motional averaging regime (MAR), was also successfully used to fit T 1 nuclear magnetic relaxation dispersion (NMRD) profiles, even outside the MAR validity range, and provided a good estimate of the particle size. On the other hand, the simultaneous fitting of T 1 and T 2 NMRD profiles by the theory was impossible, and this occurrence constitutes a clear limitation of the Roch model. Finally, the theory was shown to satisfactorily fit the deuterium T 1 NMRD profile of superparamagnetic particle suspensions in heavy water.

  5. NMR relaxation induced by iron oxide particles: testing theoretical models.

    PubMed

    Gossuin, Y; Orlando, T; Basini, M; Henrard, D; Lascialfari, A; Mattea, C; Stapf, S; Vuong, Q L

    2016-04-15

    Superparamagnetic iron oxide particles find their main application as contrast agents for cellular and molecular magnetic resonance imaging. The contrast they bring is due to the shortening of the transverse relaxation time T 2 of water protons. In order to understand their influence on proton relaxation, different theoretical relaxation models have been developed, each of them presenting a certain validity domain, which depends on the particle characteristics and proton dynamics. The validation of these models is crucial since they allow for predicting the ideal particle characteristics for obtaining the best contrast but also because the fitting of T 1 experimental data by the theory constitutes an interesting tool for the characterization of the nanoparticles. In this work, T 2 of suspensions of iron oxide particles in different solvents and at different temperatures, corresponding to different proton diffusion properties, were measured and were compared to the three main theoretical models (the motional averaging regime, the static dephasing regime, and the partial refocusing model) with good qualitative agreement. However, a real quantitative agreement was not observed, probably because of the complexity of these nanoparticulate systems. The Roch theory, developed in the motional averaging regime (MAR), was also successfully used to fit T 1 nuclear magnetic relaxation dispersion (NMRD) profiles, even outside the MAR validity range, and provided a good estimate of the particle size. On the other hand, the simultaneous fitting of T 1 and T 2 NMRD profiles by the theory was impossible, and this occurrence constitutes a clear limitation of the Roch model. Finally, the theory was shown to satisfactorily fit the deuterium T 1 NMRD profile of superparamagnetic particle suspensions in heavy water. PMID:26933908

  6. Vibration exercise for treatment of osteoporosis: a theoretical model.

    PubMed

    Aleyaasin, M; Harrigan, J J

    2008-10-01

    Orthopaedic rehabilitation of osteoporosis by muscle vibration exercise is investigated theoretically using Wolff's theory of strain-induced bone 'remodelling'. The remodelling equation for finite amplitude vibration to be transmitted to the bone via muscle corresponds to a slowly time-varying non-linear dynamic system. This slowly time-varying system is governed by a Riccatti equation with rapidly varying coefficients that oscillate with the frequency of the applied vibration. An averaging technique is used to determine the effective force transmitted to the bone. This force is expressed in terms of the stiffness and damping parameters of the connected muscle. The analytical result predicts that, in order to obtain bone reinforcement, the frequency and amplitude of vibration should not exceed specified levels. Furthermore, low-frequency vibration does not stimulate the bone sufficiently to cause significant remodelling. The theoretical model herein confirms the clinical recommendations regarding vibration exercise and its effects on rehabilitation. In a numerical example, the model predicts that a femur with reduced bone mass as a result of bed rest will be healed completely by vibration consisting of an acceleration of 2g applied at a frequency of 30 Hz over a period of 250 days.

  7. Sampling artifact in volume weighted velocity measurement. I. Theoretical modeling

    NASA Astrophysics Data System (ADS)

    Zhang, Pengjie; Zheng, Yi; Jing, Yipeng

    2015-02-01

    Cosmology based on large scale peculiar velocity prefers volume weighted velocity statistics. However, measuring the volume weighted velocity statistics from inhomogeneously distributed galaxies (simulation particles/halos) suffers from an inevitable and significant sampling artifact. We study this sampling artifact in the velocity power spectrum measured by the nearest particle velocity assignment method by Zheng et al., [Phys. Rev. D 88, 103510 (2013).]. We derive the analytical expression of leading and higher order terms. We find that the sampling artifact suppresses the z =0 E -mode velocity power spectrum by ˜10 % at k =0.1 h /Mpc , for samples with number density 10-3 (Mpc /h )-3 . This suppression becomes larger for larger k and for sparser samples. We argue that this source of systematic errors in peculiar velocity cosmology, albeit severe, can be self-calibrated in the framework of our theoretical modelling. We also work out the sampling artifact in the density-velocity cross power spectrum measurement. A more robust evaluation of related statistics through simulations will be presented in a companion paper by Zheng et al., [Sampling artifact in volume weighted velocity measurement. II. Detection in simulations and comparison with theoretical modelling, arXiv:1409.6809.]. We also argue that similar sampling artifact exists in other velocity assignment methods and hence must be carefully corrected to avoid systematic bias in peculiar velocity cosmology.

  8. Toward a theoretically based measurement model of the good life.

    PubMed

    Cheung, C K

    1997-06-01

    A theoretically based conceptualization of the good life should differentiate 4 dimensions-the hedonist good life, the dialectical good life, the humanist good life, and the formalist good life. These 4 dimensions incorporate previous fragmentary measures, such as life satisfaction, depression, work alienation, and marital satisfaction, to produce an integrative view. In the present study, 276 Hong Kong Chinese husbands and wives responded to a survey of 13 indicators for these 4 good life dimensions. Confirmatory hierarchical factor analysis showed that these indicators identified the 4 dimensions of the good life, which in turn converged to identify a second-order factor of the overall good life. The model demonstrates discriminant validity in that the first-order factors had high loadings on the overall good life factor despite being linked by a social desirability factor. Analysis further showed that the second-order factor model applied equally well to husbands and wives. Thus, the conceptualization appears to be theoretically and empirically adequate in incorporating previous conceptualizations of the good life. PMID:9168589

  9. Theoretical models of efficiency for polycrystalline thin film solar cells. Quarterly progress report No. 1, September 1, 1979-January 31, 1980

    SciTech Connect

    Not Available

    1980-03-01

    The literature on Schottky and MIS diodes has been thoroughly reviewed. Underlying the accepted theoretical models for MIS devices, a major weakness in the handling of current flow through the insulating layer was identified. An alternate model, presently only partially developed quantitatively is presented.

  10. Theoretical models for Type I and Type II supernova

    SciTech Connect

    Woosley, S.E.; Weaver, T.A.

    1985-01-01

    Recent theoretical progress in understanding the origin and nature of Type I and Type II supernovae is discussed. New Type II presupernova models characterized by a variety of iron core masses at the time of collapse are presented and the sensitivity to the reaction rate /sup 12/C(..cap alpha..,..gamma..)/sup 16/O explained. Stars heavier than about 20 M/sub solar/ must explode by a ''delayed'' mechanism not directly related to the hydrodynamical core bounce and a subset is likely to leave black hole remnants. The isotopic nucleosynthesis expected from these massive stellar explosions is in striking agreement with the sun. Type I supernovae result when an accreting white dwarf undergoes a thermonuclear explosion. The critical role of the velocity of the deflagration front in determining the light curve, spectrum, and, especially, isotopic nucleosynthesis in these models is explored. 76 refs., 8 figs.

  11. A Lifecourse Model of Multimorbidity Resilience: Theoretical and Research Developments.

    PubMed

    Wister, Andrew V; Coatta, Katherine L; Schuurman, Nadine; Lear, Scott A; Rosin, Miriam; MacKey, Dawn

    2016-04-01

    The purpose of this article is to advance a Lifecourse Model of Multimorbidity Resilience. It focuses on the ways in which individuals face adversities associated with multimorbidity and regain a sense of wellness through a complex, dynamic phenomenon termed resilience. A comprehensive review of 112 publications (between 1995 and 2015) was conducted using several comprehensive electronic data bases. Two independent researchers extracted and synthesized resilience literature with specific applications to chronic illness. The article outlines five stages of theoretical development of resilience, synthesizes these with the aging and chronic illness literature, builds a rationale for a lifecourse approach to resilience, and applies the model to multimorbidity. Cultivating and maintaining resilience is fundamental to functioning and quality of life for those with multimorbidity. We found that there are a number of gaps in both basic and applied research that need to be filled to advance knowledge and practice based on resilience approaches. PMID:27076489

  12. Development of theoretical models of integrated millimeter wave antennas

    NASA Technical Reports Server (NTRS)

    Yngvesson, K. Sigfrid; Schaubert, Daniel H.

    1991-01-01

    Extensive radiation patterns for Linear Tapered Slot Antenna (LTSA) Single Elements are presented. The directivity of LTSA elements is predicted correctly by taking the cross polarized pattern into account. A moment method program predicts radiation patterns for air LTSAs with excellent agreement with experimental data. A moment method program was also developed for the task LTSA Array Modeling. Computations performed with this program are in excellent agreement with published results for dipole and monopole arrays, and with waveguide simulator experiments, for more complicated structures. Empirical modeling of LTSA arrays demonstrated that the maximum theoretical element gain can be obtained. Formulations were also developed for calculating the aperture efficiency of LTSA arrays used in reflector systems. It was shown that LTSA arrays used in multibeam systems have a considerable advantage in terms of higher packing density, compared with waveguide feeds. Conversion loss of 10 dB was demonstrated at 35 GHz.

  13. A Lifecourse Model of Multimorbidity Resilience: Theoretical and Research Developments.

    PubMed

    Wister, Andrew V; Coatta, Katherine L; Schuurman, Nadine; Lear, Scott A; Rosin, Miriam; MacKey, Dawn

    2016-04-01

    The purpose of this article is to advance a Lifecourse Model of Multimorbidity Resilience. It focuses on the ways in which individuals face adversities associated with multimorbidity and regain a sense of wellness through a complex, dynamic phenomenon termed resilience. A comprehensive review of 112 publications (between 1995 and 2015) was conducted using several comprehensive electronic data bases. Two independent researchers extracted and synthesized resilience literature with specific applications to chronic illness. The article outlines five stages of theoretical development of resilience, synthesizes these with the aging and chronic illness literature, builds a rationale for a lifecourse approach to resilience, and applies the model to multimorbidity. Cultivating and maintaining resilience is fundamental to functioning and quality of life for those with multimorbidity. We found that there are a number of gaps in both basic and applied research that need to be filled to advance knowledge and practice based on resilience approaches.

  14. Accept/decline decision module for the liver simulated allocation model.

    PubMed

    Kim, Sang-Phil; Gupta, Diwakar; Israni, Ajay K; Kasiske, Bertram L

    2015-03-01

    Simulated allocation models (SAMs) are used to evaluate organ allocation policies. An important component of SAMs is a module that decides whether each potential recipient will accept an offered organ. The objective of this study was to develop and test accept-or-decline classifiers based on several machine-learning methods in an effort to improve the SAM for liver allocation. Feature selection and imbalance correction methods were tested and best approaches identified for application to organ transplant data. Then, we used 2011 liver match-run data to compare classifiers based on logistic regression, support vector machines, boosting, classification and regression trees, and Random Forests. Finally, because the accept-or-decline module will be embedded in a simulation model, we also developed an evaluation tool for comparing performance of predictors, which we call sample-path accuracy. The Random Forest method resulted in the smallest overall error rate, and boosting techniques had greater accuracy when both sensitivity and specificity were simultaneously considered important. Our comparisons show that no method dominates all others on all performance measures of interest. A logistic regression-based classifier is easy to implement and allows for pinpointing the contribution of each feature toward the probability of acceptance. Other methods we tested did not have a similar interpretation. The Scientific Registry of Transplant Recipients decided to use the logistic regression-based accept-decline decision module in the next generation of liver SAM.

  15. Theoretical and numerical study of axisymmetric lattice Boltzmann models

    NASA Astrophysics Data System (ADS)

    Huang, Haibo; Lu, Xi-Yun

    2009-07-01

    The forcing term in the lattice Boltzmann equation (LBE) is usually used to mimic Navier-Stokes equations with a body force. To derive axisymmetric model, forcing terms are incorporated into the two-dimensional (2D) LBE to mimic the additional axisymmetric contributions in 2D Navier-Stokes equations in cylindrical coordinates. Many axisymmetric lattice Boltzmann D2Q9 models were obtained through the Chapman-Enskog expansion to recover the 2D Navier-Stokes equations in cylindrical coordinates [I. Halliday , Phys. Rev. E 64, 011208 (2001); K. N. Premnath and J. Abraham, Phys. Rev. E 71, 056706 (2005); T. S. Lee, H. Huang, and C. Shu, Int. J. Mod. Phys. C 17, 645 (2006); T. Reis and T. N. Phillips, Phys. Rev. E 75, 056703 (2007); J. G. Zhou, Phys. Rev. E 78, 036701 (2008)]. The theoretical differences between them are discussed in detail. Numerical studies were also carried out by simulating two different flows to make a comparison on these models’ accuracy and τ sensitivity. It is found all these models are able to obtain accurate results and have the second-order spatial accuracy. However, the model C [J. G. Zhou, Phys. Rev. E 78, 036701 (2008)] is the most stable one in terms of τ sensitivity. It is also found that if density of fluid is defined in its usual way and not directly relevant to source terms, the lattice Boltzmann model seems more stable.

  16. Theoretical and computer models of detonation in solid explosives

    SciTech Connect

    Tarver, C.M.; Urtiew, P.A.

    1997-10-01

    Recent experimental and theoretical advances in understanding energy transfer and chemical kinetics have led to improved models of detonation waves in solid explosives. The Nonequilibrium Zeldovich - von Neumann - Doring (NEZND) model is supported by picosecond laser experiments and molecular dynamics simulations of the multiphonon up-pumping and internal vibrational energy redistribution (IVR) processes by which the unreacted explosive molecules are excited to the transition state(s) preceding reaction behind the leading shock front(s). High temperature, high density transition state theory calculates the induction times measured by laser interferometric techniques. Exothermic chain reactions form product gases in highly excited vibrational states, which have been demonstrated to rapidly equilibrate via supercollisions. Embedded gauge and Fabry-Perot techniques measure the rates of reaction product expansion as thermal and chemical equilibrium is approached. Detonation reaction zone lengths in carbon-rich condensed phase explosives depend on the relatively slow formation of solid graphite or diamond. The Ignition and Growth reactive flow model based on pressure dependent reaction rates and Jones-Wilkins-Lee (JWL) equations of state has reproduced this nanosecond time resolved experimental data and thus has yielded accurate average reaction zone descriptions in one-, two- and three- dimensional hydrodynamic code calculations. The next generation reactive flow model requires improved equations of state and temperature dependent chemical kinetics. Such a model is being developed for the ALE3D hydrodynamic code, in which heat transfer and Arrhenius kinetics are intimately linked to the hydrodynamics.

  17. An Investigation of the Integrated Model of User Technology Acceptance: Internet User Samples in Four Countries

    ERIC Educational Resources Information Center

    Fusilier, Marcelline; Durlabhji, Subhash; Cucchi, Alain

    2008-01-01

    National background of users may influence the process of technology acceptance. The present study explored this issue with the new, integrated technology use model proposed by Sun and Zhang (2006). Data were collected from samples of college students in India, Mauritius, Reunion Island, and United States. Questionnaire methodology and…

  18. Perceived Convenience in an Extended Technology Acceptance Model: Mobile Technology and English Learning for College Students

    ERIC Educational Resources Information Center

    Chang, Chi-Cheng; Yan, Chi-Fang; Tseng, Ju-Shih

    2012-01-01

    Since convenience is one of the features for mobile learning, does it affect attitude and intention of using mobile technology? The technology acceptance model (TAM), proposed by David (1989), was extended with perceived convenience in the present study. With regard to English language mobile learning, the variables in the extended TAM and its…

  19. Invariance of an Extended Technology Acceptance Model Across Gender and Age Group

    ERIC Educational Resources Information Center

    Ahmad, Tunku Badariah Tunku; Madarsha, Kamal Basha; Zainuddin, Ahmad Marzuki; Ismail, Nik Ahmad Hisham; Khairani, Ahmad Zamri; Nordin, Mohamad Sahari

    2011-01-01

    In this study, we examined the likelihood of a TAME (extended technology acceptance model), in which the interrelationships among computer self-efficacy, perceived usefulness, intention to use and self-reported use of computer-mediated technology were tested. In addition, the gender- and age-invariant of its causal structure were evaluated. The…

  20. Extended TAM Model: Impacts of Convenience on Acceptance and Use of Moodle

    ERIC Educational Resources Information Center

    Hsu, Hsiao-hui; Chang, Yu-ying

    2013-01-01

    The increasing online access to courses, programs, and information has shifted the control and responsibility of learning process from instructors to learners. Learners' perceptions of and attitudes toward e-learning constitute a critical factor to the success of such system. The purpose of this study is to take TAM (technology acceptance model)…

  1. The technology acceptance model: predicting nurses' intention to use telemedicine technology (eICU).

    PubMed

    Kowitlawakul, Yanika

    2011-07-01

    The purposes of this study were to determine factors and predictors that influence nurses' intention to use the eICU technology, to examine the applicability of the Technology Acceptance Model in explaining nurses' intention to use the eICU technology in healthcare settings, and to provide psychometric evidence of the measurement scales used in the study. The study involved 117 participants from two healthcare systems. The Telemedicine Technology Acceptance Model was developed based on the original Technology Acceptance Model that was initially developed by Fred Davis in 1986. The eICU Acceptance Survey was used as an instrument for the study. Content validity was examined, and the reliability of the instrument was tested. The results show that perceived usefulness is the most influential factor that influences nurses' intention to use the eICU technology. The principal factors that influence perceived usefulness are perceived ease of use, support from physicians, and years working in the hospital. The model fit was reasonably adequate and able to explain 58% of the variance (R = 0.58) in intention to use the eICU technology with the nursing sample.

  2. Examining the Factors That Contribute to Successful Database Application Implementation Using the Technology Acceptance Model

    ERIC Educational Resources Information Center

    Nworji, Alexander O.

    2013-01-01

    Most organizations spend millions of dollars due to the impact of improperly implemented database application systems as evidenced by poor data quality problems. The purpose of this quantitative study was to use, and extend, the technology acceptance model (TAM) to assess the impact of information quality and technical quality factors on database…

  3. Improving sleep with mindfulness and acceptance: a metacognitive model of insomnia.

    PubMed

    Ong, Jason C; Ulmer, Christi S; Manber, Rachel

    2012-11-01

    While there is an accumulating evidence to suggest that therapies using mindfulness and acceptance-based approaches have benefits for improving the symptoms of insomnia, it is unclear how these treatments work. The goal of this paper is to present a conceptual framework for the cognitive mechanisms of insomnia based upon mindfulness and acceptance approaches. The existing cognitive and behavioral models of insomnia are first reviewed and a two-level model of cognitive (primary) and metacognitive (secondary) arousal is presented in the context of insomnia. We then focus on the role of metacognition in mindfulness and acceptance-based therapies, followed by a review of these therapies in the treatment of insomnia. A conceptual framework is presented detailing the mechanisms of metacognition in the context of insomnia treatments. This model proposes that increasing awareness of the mental and physical states that are present when experiencing insomnia symptoms and then learning how to shift mental processes can promote an adaptive stance to one's response to these symptoms. These metacognitive processes are characterized by balanced appraisals, cognitive flexibility, equanimity, and commitment to values and are posited to reduce sleep-related arousal, leading to remission from insomnia. We hope that this model will further the understanding and impact of mindfulness and acceptance-based approaches to insomnia.

  4. 24 CFR 200.926c - Model code provisions for use in partially accepted code jurisdictions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Model code provisions for use in partially accepted code jurisdictions. 200.926c Section 200.926c Housing and Urban Development Regulations Relating to Housing and Urban Development (Continued) OFFICE OF ASSISTANT SECRETARY FOR HOUSING-FEDERAL HOUSING COMMISSIONER, DEPARTMENT...

  5. Understanding Student Teachers' Behavioural Intention to Use Technology: Technology Acceptance Model (TAM) Validation and Testing

    ERIC Educational Resources Information Center

    Wong, Kung-Teck; Osman, Rosma bt; Goh, Pauline Swee Choo; Rahmat, Mohd Khairezan

    2013-01-01

    This study sets out to validate and test the Technology Acceptance Model (TAM) in the context of Malaysian student teachers' integration of their technology in teaching and learning. To establish factorial validity, data collected from 302 respondents were tested against the TAM using confirmatory factor analysis (CFA), and structural equation…

  6. Charge fractionalization in oxide heterostructures: A field-theoretical model

    NASA Astrophysics Data System (ADS)

    Karthick Selvan, M.; Panigrahi, Prasanta K.

    2016-06-01

    LaAlO3/SrTiO3 heterostructure with polar and non-polar constituents has been shown to exhibit interface metallic conductivity due to fractional charge transfer to the interface. The interface reconstruction by electron redistribution along the (001) orientation, in which half of an electron is transferred per two-dimensional unit cell to the adjacent planes, resulting in a net transfer of half of the charge to both the interface and topmost atomic planes, has been ascribed to a polar discontinuity at the interface in the polar catastrophe model. This avoids the divergence of the electrostatic potential, as the number of layers are increased, producing an oscillatory electric field and finite potential. Akin to the description of charge fractionalization in quasi-one-dimensional polyacetylene by the field-theoretic Jackiw-Rebbi model with fermions interacting with a topologically non-trivial background field, we show an analogous connection between the polar catastrophe model and the Bell-Rajaraman model, where the charge fractionalization occurs in the soliton free sector as an end effect.

  7. Modeling of rolling element bearing mechanics. Theoretical manual

    NASA Astrophysics Data System (ADS)

    Merchant, David H.; Greenhill, Lyn M.

    1994-10-01

    This report documents the theoretical basis for the Rolling Element Bearing Analysis System (REBANS) analysis code which determines the quasistatic response to external loads or displacement of three types of high-speed rolling element bearings: angular contact ball bearings; duplex angular contact ball bearings; and cylindrical roller bearings. The model includes the effects of bearing ring and support structure flexibility. It is comprised of two main programs: the Preprocessor for Bearing Analysis (PREBAN) which creates the input files for the main analysis program; and Flexibility Enhanced Rolling Element Bearing Analysis (FEREBA), the main analysis program. A companion report addresses the input instructions for and features of the computer codes. REBANS extends the capabilities of the SHABERTH (Shaft and Bearing Thermal Analysis) code to include race and housing flexibility, including such effects as dead band and preload springs.

  8. Modeling an Application's Theoretical Minimum and Average Transactional Response Times

    SciTech Connect

    Paiz, Mary Rose

    2015-04-01

    The theoretical minimum transactional response time of an application serves as a ba- sis for the expected response time. The lower threshold for the minimum response time represents the minimum amount of time that the application should take to complete a transaction. Knowing the lower threshold is beneficial in detecting anomalies that are re- sults of unsuccessful transactions. On the converse, when an application's response time falls above an upper threshold, there is likely an anomaly in the application that is causing unusual performance issues in the transaction. This report explains how the non-stationary Generalized Extreme Value distribution is used to estimate the lower threshold of an ap- plication's daily minimum transactional response time. It also explains how the seasonal Autoregressive Integrated Moving Average time series model is used to estimate the upper threshold for an application's average transactional response time.

  9. Modeling of rolling element bearing mechanics. Theoretical manual

    NASA Technical Reports Server (NTRS)

    Merchant, David H.; Greenhill, Lyn M.

    1994-01-01

    This report documents the theoretical basis for the Rolling Element Bearing Analysis System (REBANS) analysis code which determines the quasistatic response to external loads or displacement of three types of high-speed rolling element bearings: angular contact ball bearings; duplex angular contact ball bearings; and cylindrical roller bearings. The model includes the effects of bearing ring and support structure flexibility. It is comprised of two main programs: the Preprocessor for Bearing Analysis (PREBAN) which creates the input files for the main analysis program; and Flexibility Enhanced Rolling Element Bearing Analysis (FEREBA), the main analysis program. A companion report addresses the input instructions for and features of the computer codes. REBANS extends the capabilities of the SHABERTH (Shaft and Bearing Thermal Analysis) code to include race and housing flexibility, including such effects as dead band and preload springs.

  10. An opinion diffusion model with decision-making groups: The influence of the opinion's acceptability

    NASA Astrophysics Data System (ADS)

    Cheng, Zhichao; Xiong, Yang; Xu, Yiwen

    2016-11-01

    An opinion dynamic model with decision-making groups was proposed to study the process of adopting new opinions or ideas by individuals. The opinion's acceptability is introduced to distinguish the general character of different opinions. The simulation results on a free-scale network demonstrate that when two opinions have similar acceptability, the opinion supported by more decision-making groups in the beginning will eventually win the support of more agents, whereas an opinion supported by fewer decision-making groups in the beginning may be supported by the majority at the end only if it has better acceptability, and if the tolerance threshold of the society is higher than a specific value.

  11. Theoretical model for forming limit diagram predictions without initial inhomogeneity

    NASA Astrophysics Data System (ADS)

    Gologanu, Mihai; Comsa, Dan Sorin; Banabic, Dorel

    2013-05-01

    We report on our attempts to build a theoretical model for determining forming limit diagrams (FLD) based on limit analysis that, contrary to the well-known Marciniak and Kuczynski (M-K) model, does not assume the initial existence of a region with material or geometrical inhomogeneity. We first give a new interpretation based on limit analysis for the onset of necking in the M-K model. Considering the initial thickness defect along a narrow band as postulated by the M-K model, we show that incipient necking is a transition in the plastic mechanism from one of plastic flow in both the sheet and the band to another one where the sheet becomes rigid and all plastic deformation is localized in the band. We then draw on some analogies between the onset of necking in a sheet and the onset of coalescence in a porous bulk body. In fact, the main advance in coalescence modeling has been based on a similar limit analysis with an important new ingredient: the evolution of the spatial distribution of voids, due to the plastic deformation, creating weaker regions with higher porosity surrounded by sound regions with no voids. The onset of coalescence is precisely the transition from a mechanism of plastic deformation in both regions to another one, where the sound regions are rigid. We apply this new ingredient to a necking model based on limit analysis, for the first quadrant of the FLD and a porous sheet. We use Gurson's model with some recent extensions to model the porous material. We follow both the evolution of a homogeneous sheet and the evolution of the distribution of voids. At each moment we test for a potential change of plastic mechanism, by comparing the stresses in the uniform region to those in a virtual band with a larger porosity. The main difference with the coalescence of voids in a bulk solid is that the plastic mechanism for a sheet admits a supplementary degree of freedom, namely the change in the thickness of the virtual band. For strain ratios close to

  12. Modeling of a Parabolic Trough Solar Field for Acceptance Testing: A Case Study

    SciTech Connect

    Wagner, M. J.; Mehos, M. S.; Kearney, D. W.; McMahan, A. C.

    2011-01-01

    As deployment of parabolic trough concentrating solar power (CSP) systems ramps up, the need for reliable and robust performance acceptance test guidelines for the solar field is also amplified. Project owners and/or EPC contractors often require extensive solar field performance testing as part of the plant commissioning process in order to ensure that actual solar field performance satisfies both technical specifications and performance guaranties between the involved parties. Performance test code work is currently underway at the National Renewable Energy Laboratory (NREL) in collaboration with the SolarPACES Task-I activity, and within the ASME PTC-52 committee. One important aspect of acceptance testing is the selection of a robust technology performance model. NREL1 has developed a detailed parabolic trough performance model within the SAM software tool. This model is capable of predicting solar field, sub-system, and component performance. It has further been modified for this work to support calculation at subhourly time steps. This paper presents the methodology and results of a case study comparing actual performance data for a parabolic trough solar field to the predicted results using the modified SAM trough model. Due to data limitations, the methodology is applied to a single collector loop, though it applies to larger subfields and entire solar fields. Special consideration is provided for the model formulation, improvements to the model formulation based on comparison with the collected data, and uncertainty associated with the measured data. Additionally, this paper identifies modeling considerations that are of particular importance in the solar field acceptance testing process and uses the model to provide preliminary recommendations regarding acceptable steady-state testing conditions at the single-loop level.

  13. Theoretical models of adaptive energy management in small wintering birds.

    PubMed

    Brodin, Anders

    2007-10-29

    Many small passerines are resident in forests with very cold winters. Considering their size and the adverse conditions, this is a remarkable feat that requires optimal energy management in several respects, for example regulation of body fat reserves, food hoarding and night-time hypothermia. Besides their beneficial effect on survival, these behaviours also entail various costs. The scenario is complex with many potentially important factors, and this has made 'the little bird in winter' a popular topic for theoretic modellers. Many predictions could have been made intuitively, but models have been especially important when many factors interact. Predictions that hardly could have been made without models include: (i) the minimum mortality occurs at the fat level where the marginal values of starvation risk and predation risk are equal; (ii) starvation risk may also decrease when food requirement increases; (iii) mortality from starvation may correlate positively with fat reserves; (iv) the existence of food stores can increase fitness substantially even if the food is not eaten; (v) environmental changes may induce increases or decreases in the level of reserves depending on whether changes are temporary or permanent; and (vi) hoarding can also evolve under seemingly group-selectionistic conditions.

  14. Computational Graph Theoretical Model of the Zebrafish Sensorimotor Pathway

    NASA Astrophysics Data System (ADS)

    Peterson, Joshua M.; Stobb, Michael; Mazzag, Bori; Gahtan, Ethan

    2011-11-01

    Mapping the detailed connectivity patterns of neural circuits is a central goal of neuroscience and has been the focus of extensive current research [4, 3]. The best quantitative approach to analyze the acquired data is still unclear but graph theory has been used with success [3, 1]. We present a graph theoretical model with vertices and edges representing neurons and synaptic connections, respectively. Our system is the zebrafish posterior lateral line sensorimotor pathway. The goal of our analysis is to elucidate mechanisms of information processing in this neural pathway by comparing the mathematical properties of its graph to those of other, previously described graphs. We create a zebrafish model based on currently known anatomical data. The degree distributions and small-world measures of this model is compared to small-world, random and 3-compartment random graphs of the same size (with over 2500 nodes and 160,000 connections). We find that the zebrafish graph shows small-worldness similar to other neural networks and does not have a scale-free distribution of connections.

  15. Theoretical conditions for the stationary reproduction of model protocells.

    PubMed

    Mavelli, Fabio; Ruiz-Mirazo, Kepa

    2013-02-01

    In previous works we have explored the dynamics of chemically reacting proto-cellular systems, under different experimental conditions and kinetic parameters, by means of our stochastic simulation platform 'ENVIRONMENT'. In this paper we, somehow, turn the question around: accepting some broad modeling assumptions, we investigate the conditions under which simple protocells will spontaneously settle into a stationary reproducing regime, characterized by a regular growth/division cycle and the maintenance of a certain standard size and chemical composition across generations. In the first part, starting from purely geometric considerations, the condition for stationary reproduction of a protocell will be expressed in terms of a growth control coefficient (γ). Then, an explicit relationship, the osmotic synchronization condition, will be analytically derived under a set of kinetic simplifications and taking into account the osmotic pressure balance operating across the protocell membrane. In the second part of the paper, this general condition that constrains different molecular/kinetic parameters and features of the system (reaction rates, permeability coefficients, metabolite concentrations, system volume) will be applied to different cases of self-producing vesicles, predicting the stationary protocell size or lifetime. Finally, in order to test the validity of our analytic results and predictions, the case study is contrasted with data obtained through both stochastic and deterministic computational algorithms. PMID:23233152

  16. Social trust, risk perceptions and public acceptance of recycled water: testing a social-psychological model.

    PubMed

    Ross, Victoria L; Fielding, Kelly S; Louis, Winnifred R

    2014-05-01

    Faced with a severe drought, the residents of the regional city of Toowoomba, in South East Queensland, Australia were asked to consider a potable wastewater reuse scheme to supplement drinking water supplies. As public risk perceptions and trust have been shown to be key factors in acceptance of potable reuse projects, this research developed and tested a social-psychological model of trust, risk perceptions and acceptance. Participants (N = 380) were surveyed a few weeks before a referendum was held in which residents voted against the controversial scheme. Analysis using structural equation modelling showed that the more community members perceived that the water authority used fair procedures (e.g., consulting with the community and providing accurate information), the greater their sense of shared identity with the water authority. Shared social identity in turn influenced trust via increased source credibility, that is, perceptions that the water authority is competent and has the community's interest at heart. The findings also support past research showing that higher levels of trust in the water authority were associated with lower perceptions of risk, which in turn were associated with higher levels of acceptance, and vice versa. The findings have a practical application for improving public acceptance of potable recycled water schemes. PMID:24603028

  17. Social trust, risk perceptions and public acceptance of recycled water: testing a social-psychological model.

    PubMed

    Ross, Victoria L; Fielding, Kelly S; Louis, Winnifred R

    2014-05-01

    Faced with a severe drought, the residents of the regional city of Toowoomba, in South East Queensland, Australia were asked to consider a potable wastewater reuse scheme to supplement drinking water supplies. As public risk perceptions and trust have been shown to be key factors in acceptance of potable reuse projects, this research developed and tested a social-psychological model of trust, risk perceptions and acceptance. Participants (N = 380) were surveyed a few weeks before a referendum was held in which residents voted against the controversial scheme. Analysis using structural equation modelling showed that the more community members perceived that the water authority used fair procedures (e.g., consulting with the community and providing accurate information), the greater their sense of shared identity with the water authority. Shared social identity in turn influenced trust via increased source credibility, that is, perceptions that the water authority is competent and has the community's interest at heart. The findings also support past research showing that higher levels of trust in the water authority were associated with lower perceptions of risk, which in turn were associated with higher levels of acceptance, and vice versa. The findings have a practical application for improving public acceptance of potable recycled water schemes.

  18. The acceptance of in silico models for REACH: Requirements, barriers, and perspectives

    PubMed Central

    2011-01-01

    In silico models have prompted considerable interest and debate because of their potential value in predicting the properties of chemical substances for regulatory purposes. The European REACH legislation promotes innovation and encourages the use of alternative methods, but in practice the use of in silico models is still very limited. There are many stakeholders influencing the regulatory trajectory of quantitative structure-activity relationships (QSAR) models, including regulators, industry, model developers and consultants. Here we outline some of the issues and challenges involved in the acceptance of these methods for regulatory purposes. PMID:21982269

  19. Adding Innovation Diffusion Theory to the Technology Acceptance Model: Supporting Employees' Intentions to Use E-Learning Systems

    ERIC Educational Resources Information Center

    Lee, Yi-Hsuan; Hsieh, Yi-Chuan; Hsu, Chia-Ning

    2011-01-01

    This study intends to investigate factors affecting business employees' behavioral intentions to use the e-learning system. Combining the innovation diffusion theory (IDT) with the technology acceptance model (TAM), the present study proposes an extended technology acceptance model. The proposed model was tested with data collected from 552…

  20. The Effects of a Modified Treatment Package with and without Feeder Modeling on One Child's Acceptance of Novel Foods

    ERIC Educational Resources Information Center

    Seiverling, Laura; Harclerode, Whitney; Williams, Keith

    2014-01-01

    The purpose of this study was to examine if sequential presentation with feeder modeling would lead to an increase in bites accepted of new foods compared to sequential presentation without feeder modeling in a typically developing 4-year-old boy with food selectivity. The participant's acceptance of novel foods increased both in the modeling and…

  1. Model and Processes of Acceptance and Commitment Therapy (ACT) for Chronic Pain Including a Closer Look at the Self.

    PubMed

    Yu, Lin; McCracken, Lance M

    2016-02-01

    Acceptance and commitment therapy (ACT) is one of the so called "third-wave" cognitive behavioral therapies. It has been increasingly applied to chronic pain, and there is accumulating evidence to support its effectiveness. ACT is based on a model of general human functioning called the psychological flexibility (PF) model. Most facets of the PF model have been examined in chronic pain. However, a potential key facet related to "self" appears underappreciated. Indeed, a positive or healthy sense of self seems essential to our well-being, and there have been numerous studies of the self in chronic pain. At the same time, these studies are not currently well organized or easy to summarize. This lack of clarity and integration creates barriers to progress in this area of research. PF with its explicit inclusion of self-related therapeutic processes within a broad, integrative, theoretical model may help. The current review summarizes the PF model in the context of chronic pain with a specific emphasis on the parts of the model that address self-related processes. PMID:26803836

  2. Model and Processes of Acceptance and Commitment Therapy (ACT) for Chronic Pain Including a Closer Look at the Self.

    PubMed

    Yu, Lin; McCracken, Lance M

    2016-02-01

    Acceptance and commitment therapy (ACT) is one of the so called "third-wave" cognitive behavioral therapies. It has been increasingly applied to chronic pain, and there is accumulating evidence to support its effectiveness. ACT is based on a model of general human functioning called the psychological flexibility (PF) model. Most facets of the PF model have been examined in chronic pain. However, a potential key facet related to "self" appears underappreciated. Indeed, a positive or healthy sense of self seems essential to our well-being, and there have been numerous studies of the self in chronic pain. At the same time, these studies are not currently well organized or easy to summarize. This lack of clarity and integration creates barriers to progress in this area of research. PF with its explicit inclusion of self-related therapeutic processes within a broad, integrative, theoretical model may help. The current review summarizes the PF model in the context of chronic pain with a specific emphasis on the parts of the model that address self-related processes.

  3. Improvements to Nuclear Data and Its Uncertainties by Theoretical Modeling

    SciTech Connect

    Danon, Yaron; Nazarewicz, Witold; Talou, Patrick

    2013-02-18

    This project addresses three important gaps in existing evaluated nuclear data libraries that represent a significant hindrance against highly advanced modeling and simulation capabilities for the Advanced Fuel Cycle Initiative (AFCI). This project will: Develop advanced theoretical tools to compute prompt fission neutrons and gamma-ray characteristics well beyond average spectra and multiplicity, and produce new evaluated files of U and Pu isotopes, along with some minor actinides; Perform state-of-the-art fission cross-section modeling and calculations using global and microscopic model input parameters, leading to truly predictive fission cross-sections capabilities. Consistent calculations for a suite of Pu isotopes will be performed; Implement innovative data assimilation tools, which will reflect the nuclear data evaluation process much more accurately, and lead to a new generation of uncertainty quantification files. New covariance matrices will be obtained for Pu isotopes and compared to existing ones. The deployment of a fleet of safe and efficient advanced reactors that minimize radiotoxic waste and are proliferation-resistant is a clear and ambitious goal of AFCI. While in the past the design, construction and operation of a reactor were supported through empirical trials, this new phase in nuclear energy production is expected to rely heavily on advanced modeling and simulation capabilities. To be truly successful, a program for advanced simulations of innovative reactors will have to develop advanced multi-physics capabilities, to be run on massively parallel super- computers, and to incorporate adequate and precise underlying physics. And all these areas have to be developed simultaneously to achieve those ambitious goals. Of particular interest are reliable fission cross-section uncertainty estimates (including important correlations) and evaluations of prompt fission neutrons and gamma-ray spectra and uncertainties.

  4. A theoretical model for the Lorentz force particle analyzer

    NASA Astrophysics Data System (ADS)

    Moreau, René; Tao, Zhen; Wang, Xiaodong

    2016-07-01

    In a previous paper [X. Wang et al., J. Appl. Phys. 120, 014903 (2016)], several experimental devices have been presented, which demonstrate the efficiency of electromagnetic techniques for detecting and sizing electrically insulating particles entrained in the flow of a molten metal. In each case, a non-uniform magnetic field is applied across the flow of the electrically conducting liquid, thereby generating a braking Lorentz force on this moving medium and a reaction force on the magnet, which tends to be entrained in the flow direction. The purpose of this letter is to derive scaling laws for this Lorentz force from an elementary theoretical model. For simplicity, as in the experiments, the flowing liquid is modeled as a solid body moving with a uniform velocity U. The eddy currents in the moving domain are derived from the classic induction equation and Ohm's law, and expressions for the Lorentz force density j ×B and for its integral over the entire moving domain follow. The insulating particles that are eventually present and entrained with this body are then treated as small disturbances in a classic perturbation analysis, thereby leading to scaling laws for the pulses they generate in the Lorentz force. The purpose of this letter is both to illustrate the eddy currents without and with insulating particles in the electrically conducting liquid and to derive a key relation between the pulses in the Lorentz force and the main parameters (particle volume and dimensions of the region subjected to the magnetic field).

  5. Collective behavior in animal groups: theoretical models and empirical studies

    PubMed Central

    Giardina, Irene

    2008-01-01

    Collective phenomena in animal groups have attracted much attention in the last years, becoming one of the hottest topics in ethology. There are various reasons for this. On the one hand, animal grouping provides a paradigmatic example of self-organization, where collective behavior emerges in absence of centralized control. The mechanism of group formation, where local rules for the individuals lead to a coherent global state, is very general and transcends the detailed nature of its components. In this respect, collective animal behavior is a subject of great interdisciplinary interest. On the other hand, there are several important issues related to the biological function of grouping and its evolutionary success. Research in this field boasts a number of theoretical models, but much less empirical results to compare with. For this reason, even if the general mechanisms through which self-organization is achieved are qualitatively well understood, a quantitative test of the models assumptions is still lacking. New analysis on large groups, which require sophisticated technological procedures, can provide the necessary empirical data. PMID:19404431

  6. A game theoretic model of drug launch in India.

    PubMed

    Bhaduri, Saradindu; Ray, Amit Shovon

    2006-01-01

    There is a popular belief that drug launch is delayed in developing countries like India because of delayed transfer of technology due to a 'post-launch' imitation threat through weak intellectual property rights (IPR). In fact, this belief has been a major reason for the imposition of the Trade Related Intellectual Property Rights regime under the WTO. This construct undermines the fact that in countries like India, with high reverse engineering capabilities, imitation can occur even before the formal technology transfer, and fails to recognize the first mover advantage in pharmaceutical markets. This paper argues that the first mover advantage is important and will vary across therapeutic areas, especially in developing countries with diverse levels of patient enlightenment and quality awareness. We construct a game theoretic model of incomplete information to examine the delay in drug launch in terms of costs and benefits of first move, assumed to be primarily a function of the therapeutic area of the new drug. Our model shows that drug launch will be delayed only for external (infective/communicable) diseases, while drugs for internal, non-communicable diseases (accounting for the overwhelming majority of new drug discovery) will be launched without delay. PMID:18634701

  7. Posttraumatic Stress Disorder: A Theoretical Model of the Hyperarousal Subtype

    PubMed Central

    Weston, Charles Stewart E.

    2014-01-01

    Posttraumatic stress disorder (PTSD) is a frequent and distressing mental disorder, about which much remains to be learned. It is a heterogeneous disorder; the hyperarousal subtype (about 70% of occurrences and simply termed PTSD in this paper) is the topic of this article, but the dissociative subtype (about 30% of occurrences and likely involving quite different brain mechanisms) is outside its scope. A theoretical model is presented that integrates neuroscience data on diverse brain regions known to be involved in PTSD, and extensive psychiatric findings on the disorder. Specifically, the amygdala is a multifunctional brain region that is crucial to PTSD, and processes peritraumatic hyperarousal on grounded cognition principles to produce hyperarousal symptoms. Amygdala activity also modulates hippocampal function, which is supported by a large body of evidence, and likewise amygdala activity modulates several brainstem regions, visual cortex, rostral anterior cingulate cortex (rACC), and medial orbitofrontal cortex (mOFC), to produce diverse startle, visual, memory, numbing, anger, and recklessness symptoms. Additional brain regions process other aspects of peritraumatic responses to produce further symptoms. These contentions are supported by neuroimaging, neuropsychological, neuroanatomical, physiological, cognitive, and behavioral evidence. Collectively, the model offers an account of how responses at the time of trauma are transformed into an extensive array of the 20 PTSD symptoms that are specified in the Diagnostic and Statistical Manual of Mental Disorders, Fifth edition. It elucidates the neural mechanisms of a specific form of psychopathology, and accords with the Research Domain Criteria framework. PMID:24772094

  8. Theoretical model of prion propagation: a misfolded protein induces misfolding.

    PubMed

    Małolepsza, Edyta; Boniecki, Michal; Kolinski, Andrzej; Piela, Lucjan

    2005-05-31

    There is a hypothesis that dangerous diseases such as bovine spongiform encephalopathy, Creutzfeldt-Jakob, Alzheimer's, fatal familial insomnia, and several others are induced by propagation of wrong or misfolded conformations of some vital proteins. If for some reason the misfolded conformations were acquired by many such protein molecules it might lead to a "conformational" disease of the organism. Here, a theoretical model of the molecular mechanism of such a conformational disease is proposed, in which a metastable (or misfolded) form of a protein induces a similar misfolding of another protein molecule (conformational autocatalysis). First, a number of amino acid sequences composed of 32 aa have been designed that fold rapidly into a well defined native-like alpha-helical conformation. From a large number of such sequences a subset of 14 had a specific feature of their energy landscape, a well defined local energy minimum (higher than the global minimum for the alpha-helical fold) corresponding to beta-type structure. Only one of these 14 sequences exhibited a strong autocatalytic tendency to form a beta-sheet dimer capable of further propagation of protofibril-like structure. Simulations were done by using a reduced, although of high resolution, protein model and the replica exchange Monte Carlo sampling procedure. PMID:15911770

  9. Theoretical model of prion propagation: A misfolded protein induces misfolding

    PubMed Central

    Małolepsza, Edyta; Boniecki, Michał; Kolinski, Andrzej; Piela, Lucjan

    2005-01-01

    There is a hypothesis that dangerous diseases such as bovine spongiform encephalopathy, Creutzfeldt-Jakob, Alzheimer's, fatal familial insomnia, and several others are induced by propagation of wrong or misfolded conformations of some vital proteins. If for some reason the misfolded conformations were acquired by many such protein molecules it might lead to a “conformational” disease of the organism. Here, a theoretical model of the molecular mechanism of such a conformational disease is proposed, in which a metastable (or misfolded) form of a protein induces a similar misfolding of another protein molecule (conformational autocatalysis). First, a number of amino acid sequences composed of 32 aa have been designed that fold rapidly into a well defined native-like α-helical conformation. From a large number of such sequences a subset of 14 had a specific feature of their energy landscape, a well defined local energy minimum (higher than the global minimum for the α-helical fold) corresponding to β-type structure. Only one of these 14 sequences exhibited a strong autocatalytic tendency to form a β-sheet dimer capable of further propagation of protofibril-like structure. Simulations were done by using a reduced, although of high resolution, protein model and the replica exchange Monte Carlo sampling procedure. PMID:15911770

  10. Integrating Health Belief Model and Technology Acceptance Model: An Investigation of Health-Related Internet Use

    PubMed Central

    2015-01-01

    Background Today, people use the Internet to satisfy health-related information and communication needs. In Malaysia, Internet use for health management has become increasingly significant due to the increase in the incidence of chronic diseases, in particular among urban women and their desire to stay healthy. Past studies adopted the Technology Acceptance Model (TAM) and Health Belief Model (HBM) independently to explain Internet use for health-related purposes. Although both the TAM and HBM have their own merits, independently they lack the ability to explain the cognition and the related mechanism in which individuals use the Internet for health purposes. Objective This study aimed to examine the influence of perceived health risk and health consciousness on health-related Internet use based on the HBM. Drawing on the TAM, it also tested the mediating effects of perceived usefulness of the Internet for health information and attitude toward Internet use for health purposes for the relationship between health-related factors, namely perceived health risk and health consciousness on health-related Internet use. Methods Data obtained for the current study were collected using purposive sampling; the sample consisted of women in Malaysia who had Internet access. The partial least squares structural equation modeling method was used to test the research hypotheses developed. Results Perceived health risk (β=.135, t 1999=2.676) and health consciousness (β=.447, t 1999=9.168) had a positive influence on health-related Internet use. Moreover, perceived usefulness of the Internet and attitude toward Internet use for health-related purposes partially mediated the influence of health consciousness on health-related Internet use (β=.025, t 1999=3.234), whereas the effect of perceived health risk on health-related Internet use was fully mediated by perceived usefulness of the Internet and attitude (β=.029, t 1999=3.609). These results suggest the central role of

  11. Empirical STORM-E Model. [I. Theoretical and Observational Basis

    NASA Technical Reports Server (NTRS)

    Mertens, Christopher J.; Xu, Xiaojing; Bilitza, Dieter; Mlynczak, Martin G.; Russell, James M., III

    2013-01-01

    Auroral nighttime infrared emission observed by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument onboard the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics (TIMED) satellite is used to develop an empirical model of geomagnetic storm enhancements to E-region peak electron densities. The empirical model is called STORM-E and will be incorporated into the 2012 release of the International Reference Ionosphere (IRI). The proxy for characterizing the E-region response to geomagnetic forcing is NO+(v) volume emission rates (VER) derived from the TIMED/SABER 4.3 lm channel limb radiance measurements. The storm-time response of the NO+(v) 4.3 lm VER is sensitive to auroral particle precipitation. A statistical database of storm-time to climatological quiet-time ratios of SABER-observed NO+(v) 4.3 lm VER are fit to widely available geomagnetic indices using the theoretical framework of linear impulse-response theory. The STORM-E model provides a dynamic storm-time correction factor to adjust a known quiescent E-region electron density peak concentration for geomagnetic enhancements due to auroral particle precipitation. Part II of this series describes the explicit development of the empirical storm-time correction factor for E-region peak electron densities, and shows comparisons of E-region electron densities between STORM-E predictions and incoherent scatter radar measurements. In this paper, Part I of the series, the efficacy of using SABER-derived NO+(v) VER as a proxy for the E-region response to solar-geomagnetic disturbances is presented. Furthermore, a detailed description of the algorithms and methodologies used to derive NO+(v) VER from SABER 4.3 lm limb emission measurements is given. Finally, an assessment of key uncertainties in retrieving NO+(v) VER is presented

  12. An Empirical Assessment of a Technology Acceptance Model for Apps in Medical Education.

    PubMed

    Briz-Ponce, Laura; García-Peñalvo, Francisco José

    2015-11-01

    The evolution and the growth of mobile applications ("apps") in our society is a reality. This general trend is still upward and the app use has also penetrated the medical education community. However, there is a lot of unawareness of the students' and professionals' point of view about introducing "apps" within Medical School curriculum. The aim of this research is to design, implement and verify that the Technology Acceptance Model (TAM) can be employed to measure and explain the acceptance of mobile technology and "apps" within Medical Education. The methodology was based on a survey distributed to students and medical professionals from University of Salamanca. This model explains 46.7% of behavioral intention to use mobile devise or "apps" for learning and will help us to justify and understand the current situation of introducing "apps" into the Medical School curriculum. PMID:26411928

  13. An Empirical Assessment of a Technology Acceptance Model for Apps in Medical Education.

    PubMed

    Briz-Ponce, Laura; García-Peñalvo, Francisco José

    2015-11-01

    The evolution and the growth of mobile applications ("apps") in our society is a reality. This general trend is still upward and the app use has also penetrated the medical education community. However, there is a lot of unawareness of the students' and professionals' point of view about introducing "apps" within Medical School curriculum. The aim of this research is to design, implement and verify that the Technology Acceptance Model (TAM) can be employed to measure and explain the acceptance of mobile technology and "apps" within Medical Education. The methodology was based on a survey distributed to students and medical professionals from University of Salamanca. This model explains 46.7% of behavioral intention to use mobile devise or "apps" for learning and will help us to justify and understand the current situation of introducing "apps" into the Medical School curriculum.

  14. Theoretical Biology and Medical Modelling: ensuring continued growth and future leadership.

    PubMed

    Nishiura, Hiroshi; Rietman, Edward A; Wu, Rongling

    2013-07-11

    Theoretical biology encompasses a broad range of biological disciplines ranging from mathematical biology and biomathematics to philosophy of biology. Adopting a broad definition of "biology", Theoretical Biology and Medical Modelling, an open access journal, considers original research studies that focus on theoretical ideas and models associated with developments in biology and medicine.

  15. Sequence design in lattice models by graph theoretical methods

    NASA Astrophysics Data System (ADS)

    Sanjeev, B. S.; Patra, S. M.; Vishveshwara, S.

    2001-01-01

    A general strategy has been developed based on graph theoretical methods, for finding amino acid sequences that take up a desired conformation as the native state. This problem of inverse design has been addressed by assigning topological indices for the monomer sites (vertices) of the polymer on a 3×3×3 cubic lattice. This is a simple design strategy, which takes into account only the topology of the target protein and identifies the best sequence for a given composition. The procedure allows the design of a good sequence for a target native state by assigning weights for the vertices on a lattice site in a given conformation. It is seen across a variety of conformations that the predicted sequences perform well both in sequence and in conformation space, in identifying the target conformation as native state for a fixed composition of amino acids. Although the method is tested in the framework of the HP model [K. F. Lau and K. A. Dill, Macromolecules 22, 3986 (1989)] it can be used in any context if proper potential functions are available, since the procedure derives unique weights for all the sites (vertices, nodes) of the polymer chain of a chosen conformation (graph).

  16. Theoretical model of superconducting spintronic SIsFS devices

    NASA Astrophysics Data System (ADS)

    Bakurskiy, S. V.; Klenov, N. V.; Soloviev, I. I.; Bol'ginov, V. V.; Ryazanov, V. V.; Vernik, I. V.; Mukhanov, O. A.; Kupriyanov, M. Yu.; Golubov, A. A.

    2013-05-01

    Motivated by recent progress in the development of cryogenic memory compatible with single flux quantum (SFQ) circuits, we have performed a theoretical study of magnetic SIsFS Josephson junctions, where "S" is a bulk superconductor, "s" is a thin superconducting film, "F" is a metallic ferromagnet, and "I" is an insulator. We calculate the Josephson current as a function of s and F layers thickness, temperature, and exchange energy of F film. We outline several modes of operation of these junctions and demonstrate their unique ability to have large product of a critical current IC and a normal-state resistance RN in the π state, comparable to that in superconductor-insulator-superconductor tunnel junctions commonly used in SFQ circuits. We develop a model describing switching of the Josephson critical current in these devices by external magnetic field. The results are in good agreement with the experimental data for Nb-Al/AlOx-Nb-Pd0.99Fe0.01-Nb junctions.

  17. Thermophotonic heat pump—a theoretical model and numerical simulations

    NASA Astrophysics Data System (ADS)

    Oksanen, Jani; Tulkki, Jukka

    2010-05-01

    We have recently proposed a solid state heat pump based on photon mediated heat transfer between two large-area light emitting diodes coupled by the electromagnetic field and enclosed in a semiconductor structure with a nearly homogeneous refractive index. Ideally the thermophotonic heat pump (THP) allows heat transfer at Carnot efficiency but in reality there are several factors that limit the efficiency. The efficient operation of the THP is based on the following construction factors and operational characteristics: (1) broad area semiconductor diodes to enable operation at optimal carrier density and high efficiency, (2) recycling of the energy of the emitted photons, (3) elimination of photon extraction losses by integrating the emitting and the absorbing diodes within a single semiconductor structure, and (4) eliminating the reverse thermal conduction by a nanometer scale vacuum layer between the diodes. In this paper we develop a theoretical model for the THP and study the fundamental physical limitations and potential of the concept. The results show that even when the most important losses of the THPs are accounted for, the THP has potential to outperform the thermoelectric coolers especially for heat transfer across large temperature differences and possibly even to compete with conventional small scale compressor based heat pumps.

  18. Membranes and theoretical modeling of membrane distillation: a review.

    PubMed

    Khayet, Mohamed

    2011-05-11

    Membrane distillation (MD) is one of the non-isothermal membrane separation processes used in various applications such desalination, environmental/waste cleanup, food, etc. It is known since 1963 and is still being developed at laboratory stage for different purposes and not fully implemented in industry. An abrupt increase in the number of papers on MD membrane engineering (i.e. design, fabrication and testing in MD) is seen since only 6 years ago. The present paper offers a comprehensive MD state-of-the-art review covering a wide range of commercial membranes, MD membrane engineering, their MD performance, transport mechanisms, experimental and theoretical modeling of different MD configurations as well as recent developments in MD. Improved MD membranes with specific morphology, micro- and nano-structures are highly demanded. Membranes with different pore sizes, porosities, thicknesses and materials as well as novel structures are required in order to carry out systematic MD studies for better understanding mass transport in different MD configurations, thereby improving the MD performance and looking for MD industrialization.

  19. Strengthening Theoretical Testing in Criminology Using Agent-based Modeling

    PubMed Central

    Groff, Elizabeth R.

    2014-01-01

    Objectives: 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. Method: 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. Results: 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. Conclusion: 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. PMID:25419001

  20. Theoretical models for the polarization of astronomical masers

    NASA Astrophysics Data System (ADS)

    Western, L. R.

    Theoretical models for the creation of linear polarization in astronomical masers are developed. Equations are obtained that describe the transfer of the linearly polarized radiation in two and three dimensional astronomical masers. The transfer equations presented here include both polarization and intersecting maser rays. The transfer equations are integrated to find the intensity of radiation emitted by spheres, spherical shells and thin disks. The calculations show that apparent sizes due to beaming are still quite small and comparable to those obtained using the scalar molecular approximation. Long tails and substantial differences between the two linear polarizations occur in the angular distributions calculated here, especially for disk-like geometries, due to the effect of individual magnetic substates. Further calculations show that small anisotropies (approximately 10%) in the excitation can lead to very high linear polarization (approximately 90%) of the radiation from saturated astronomical masers. Separate calculations are performed for the transfer of the vibrational radiation of molecular SiO through a spherical gas shell. A major result is that magnetic fields alone can not account for the high linear polarization observations of the SiO v = 1, J = 2 ranges to 1 astronomical maser.

  1. Results of an emergency response atmospheric dispersion model comparison using a state accepted statistical protocol

    SciTech Connect

    Ciolek, J.T. Jr.

    1993-10-01

    The Rocky Flats Plant, located approximately 26 km northwest of downtown Denver, Colorado, has developed an emergency response atmospheric dispersion model for complex terrain applications. Plant personnel would use the model, known as the Terrain-Responsive Atmospheric Code (TRAC) (Hodgin 1985) to project plume impacts and provide off-site protective action recommendations to the State of Colorado should a hazardous material release occur from the facility. The Colorado Department of Health (CDH) entered into an interagency agreement with the Rocky Flats Plant prime contractor, EG&G Rocky Flats, and the US Department of Energy to evaluate TRAC as an acceptable emergency response tool. After exhaustive research of similar evaluation processes from other emergency response and regulatory organizations, the interagency committee devised a formal acceptance process. The process contains an evaluation protocol (Hodgin and Smith 1992), descriptions of responsibilities, an identified experimental data set to use in the evaluation, and judgment criteria for model acceptance. The evaluation protocol is general enough to allow for different implementations. This paper explains one implementation, shows protocol results for a test case, and presents results of a comparison between versions of TRAC with different wind Field codes: a two dimensional mass consistent code called WINDS (Fosberg et al. 1976) that has been extended to three dimensions, and a fully 3 dimensional mass conserving code called NUATMOS (Ross and Smith 1987, Ross et al. 1988).

  2. Information-Theoretic Latent Distribution Modeling: Distinguishing Discrete and Continuous Latent Variable Models

    ERIC Educational Resources Information Center

    Markon, Kristian E.; Krueger, Robert F.

    2006-01-01

    Distinguishing between discrete and continuous latent variable distributions has become increasingly important in numerous domains of behavioral science. Here, the authors explore an information-theoretic approach to latent distribution modeling, in which the ability of latent distribution models to represent statistical information in observed…

  3. Applying the Extended Technology Acceptance Model to the Use of Clickers in Student Learning: Some Evidence from Macroeconomics Classes

    ERIC Educational Resources Information Center

    Wu, Xiaoyu; Gao, Yuan

    2011-01-01

    This paper applies the extended technology acceptance model (exTAM) in information systems research to the use of clickers in student learning. The technology acceptance model (TAM) posits that perceived ease of use and perceived usefulness of technology influence users' attitudes toward using and intention to use technology. Research subsequent…

  4. The Acceptance Model of Intuitive Eating: A Comparison of Women in Emerging Adulthood, Early Adulthood, and Middle Adulthood

    ERIC Educational Resources Information Center

    Augustus-Horvath, Casey L.; Tylka, Tracy L.

    2011-01-01

    The acceptance model of intuitive eating (Avalos & Tylka, 2006) posits that body acceptance by others helps women appreciate their body and resist adopting an observer's perspective of their body, which contribute to their eating intuitively/adaptively. We extended this model by integrating body mass index (BMI) into its structure and…

  5. Theory development in nursing and healthcare informatics: a model explaining and predicting information and communication technology acceptance by healthcare consumers.

    PubMed

    An, Ji-Young; Hayman, Laura L; Panniers, Teresa; Carty, Barbara

    2007-01-01

    About 110 million American adults are looking for health information and services on the Internet. Identification of the factors influencing healthcare consumers' technology acceptance is requisite to understanding their acceptance and usage behavior of online health information and related services. The purpose of this article is to describe the development of the Information and Communication Technology Acceptance Model (ICTAM). From the literature reviewed, ICTAM was developed with emphasis on integrating multidisciplinary perspectives from divergent frameworks and empirical findings into a unified model with regard to healthcare consumers' acceptance and usage behavior of information and services on the Internet.

  6. Modelling Facebook Usage among University Students in Thailand: The Role of Emotional Attachment in an Extended Technology Acceptance Model

    ERIC Educational Resources Information Center

    Teo, Timothy

    2016-01-01

    The aim of this study is to examine the factors that influenced the use of Facebook among university students. Using an extended technology acceptance model (TAM) with emotional attachment (EA) as an external variable, a sample of 498 students from a public-funded Thailand university were surveyed on their responses to five variables hypothesized…

  7. Measuring the Moderating Effect of Gender and Age on E-Learning Acceptance in England: A Structural Equation Modeling Approach for an Extended Technology Acceptance Model

    ERIC Educational Resources Information Center

    Tarhini, Ali; Hone, Kate; Liu, Xiaohui

    2014-01-01

    The success of an e-learning intervention depends to a considerable extent on student acceptance and use of the technology. Therefore, it has become imperative for practitioners and policymakers to understand the factors affecting the user acceptance of e-learning systems in order to enhance the students' learning experience. Based on an extended…

  8. Variation transmission model for setting acceptance criteria in a multi-staged pharmaceutical manufacturing process.

    PubMed

    Montes, Richard O

    2012-03-01

    Pharmaceutical manufacturing processes consist of a series of stages (e.g., reaction, workup, isolation) to generate the active pharmaceutical ingredient (API). Outputs at intermediate stages (in-process control) and API need to be controlled within acceptance criteria to assure final drug product quality. In this paper, two methods based on tolerance interval to derive such acceptance criteria will be evaluated. The first method is serial worst case (SWC), an industry risk minimization strategy, wherein input materials and process parameters of a stage are fixed at their worst-case settings to calculate the maximum level expected from the stage. This maximum output then becomes input to the next stage wherein process parameters are again fixed at worst-case setting. The procedure is serially repeated throughout the process until the final stage. The calculated limits using SWC can be artificially high and may not reflect the actual process performance. The second method is the variation transmission (VT) using autoregressive model, wherein variation transmitted up to a stage is estimated by accounting for the recursive structure of the errors at each stage. Computer simulations at varying extent of variation transmission and process stage variability are performed. For the scenarios tested, VT method is demonstrated to better maintain the simulated confidence level and more precisely estimate the true proportion parameter than SWC. Real data examples are also presented that corroborate the findings from the simulation. Overall, VT is recommended for setting acceptance criteria in a multi-staged pharmaceutical manufacturing process.

  9. Development of a prediction model on the acceptance of electronic laboratory notebooks in academic environments.

    PubMed

    Kloeckner, Frederik; Farkas, Robert; Franken, Tobias; Schmitz-Rode, Thomas

    2014-04-01

    Documentation of research data plays a key role in the biomedical engineering innovation processes. It makes an important contribution to the protection of intellectual property, the traceability of results and fulfilling the regulatory requirement. Because of the increasing digitalization in laboratories, an electronic alternative to the commonly-used paper-bound notebooks could contribute to the production of sophisticated documentation. However, compared to in an industrial environment, the use of electronic laboratory notebooks is not widespread in academic laboratories. Little is known about the acceptance of an electronic documentation system and the underlying reasons for this. Thus, this paper aims to establish a prediction model on the potential preference and acceptance of scientists either for paper-based or electronic documentation. The underlying data for the analysis originate from an online survey of 101 scientists in industrial, academic and clinical environments. Various parameters were analyzed to identify crucial factors for the system preference using binary logistic regression. The analysis showed significant dependency between the documentation system preference and the supposed workload associated with the documentation system (p<0.006; odds ratio=58.543) and an additional personal component. Because of the dependency of system choice on specific parameters it is possible to predict the acceptance of an electronic laboratory notebook before implementation.

  10. Acceptability of telemedicine and other cancer genetic counseling models of service delivery in geographically remote settings.

    PubMed

    McDonald, Eileen; Lamb, Amanda; Grillo, Barbara; Lucas, Lee; Miesfeldt, Susan

    2014-04-01

    This work examined acceptability of cancer genetic counseling models of service delivery among Maine residents at risk for hereditary cancer susceptibility disorders. Pre-counseling, participants ranked characteristics reflecting models of care from most to least important including: mode-of-communication (in-person versus telegenetics), provider level of training (genetic specialty versus some training/experience), delivery format (one-on-one versus group counseling), and location (local versus tertiary service requiring travel). Associations between models of care characteristic rankings and patient characteristics, including rural residence, perceived cancer risk, and perceived risk for a hereditary cancer risk susceptibility disorder were examined. A total of 149/300 (49.7% response rate) individuals from 11/16 Maine counties responded; 30.8% were from rural counties; 92.2% indicated that an important/the most important model of care characteristic is provider professional qualifications. Among other characteristics, 65.1% ranked one-on-one counseling as important/the most important. In-person and local counseling were ranked the two least important characteristics (51.8% and 52.1% important/the most important, respectively). Responses did not vary by patient characteristics with the exception of greater acceptance of group counseling among those at perceived high personal cancer risk. Cancer telegenetic services hold promise for access to expert providers in a one-on-one format for rurally remote clients.

  11. Computational model of collective nest selection by ants with heterogeneous acceptance thresholds

    PubMed Central

    Masuda, Naoki; O'shea-Wheller, Thomas A.; Doran, Carolina; Franks, Nigel R.

    2015-01-01

    Collective decision-making is a characteristic of societies ranging from ants to humans. The ant Temnothorax albipennis is known to use quorum sensing to collectively decide on a new home; emigration to a new nest site occurs when the number of ants favouring the new site becomes quorate. There are several possible mechanisms by which ant colonies can select the best nest site among alternatives based on a quorum mechanism. In this study, we use computational models to examine the implications of heterogeneous acceptance thresholds across individual ants in collective nest choice behaviour. We take a minimalist approach to develop a differential equation model and a corresponding non-spatial agent-based model. We show, consistent with existing empirical evidence, that heterogeneity in acceptance thresholds is a viable mechanism for efficient nest choice behaviour. In particular, we show that the proposed models show speed–accuracy trade-offs and speed–cohesion trade-offs when we vary the number of scouts or the quorum threshold. PMID:26543578

  12. Computational model of collective nest selection by ants with heterogeneous acceptance thresholds.

    PubMed

    Masuda, Naoki; O'shea-Wheller, Thomas A; Doran, Carolina; Franks, Nigel R

    2015-06-01

    Collective decision-making is a characteristic of societies ranging from ants to humans. The ant Temnothorax albipennis is known to use quorum sensing to collectively decide on a new home; emigration to a new nest site occurs when the number of ants favouring the new site becomes quorate. There are several possible mechanisms by which ant colonies can select the best nest site among alternatives based on a quorum mechanism. In this study, we use computational models to examine the implications of heterogeneous acceptance thresholds across individual ants in collective nest choice behaviour. We take a minimalist approach to develop a differential equation model and a corresponding non-spatial agent-based model. We show, consistent with existing empirical evidence, that heterogeneity in acceptance thresholds is a viable mechanism for efficient nest choice behaviour. In particular, we show that the proposed models show speed-accuracy trade-offs and speed-cohesion trade-offs when we vary the number of scouts or the quorum threshold. PMID:26543578

  13. A theoretical model of grainsize evolution during deformation

    NASA Astrophysics Data System (ADS)

    Ricard, Y.; Bercovici, D.; Rozel, A.

    2007-12-01

    Lithospheric shear localization, as occurs in the formation of tectonic plate boundaries, is often associated with diminished grainsize (e.g., mylonites). Grainsize reduction is typically attributed to dynamic recrystallization; however, theoretical models of shear-localization arising from this hypothesis are problematic since (1) they require the simultaneous action of two exclusive creep mechanisms (diffusion and dislocation creep), and (2) the grain-growth ("healing") laws employed by these models are derived from static grain-growth or coarsening theory, although the shear-localization setting itself is far from static equilibrium. We present a new first-principles grained-continuum theory which accounts for both coarsening and damage-induced grainsize reduction. Damage per se is the generic process for generation of microcracks, defects, dislocations (including recrystallization), subgrains, nucleii and cataclastic breakdown of grains. The theory contains coupled statistical grain-scale and continuum macroscopic components. The grain-scale element of the theory prescribes both the evolution of the grainsize distribution, and a phenomenological grain-growth law derived from non-equilibrium thermodynamics; grain-growth thus incorporates the free energy differences between grains, including both grain-boundary surface energy (which controls coarsening) and the contribution of deformational work to these free energiesconservation and positivity of entropy production provide the phenomenological law for the statistical grain-growth law. We identify four potential mechanisms that affect the distribution of grainsize; two of them conserve the number of grains but change their relative masses and two of them change the number of grains by sticking them together or breaking them. In the limit of static equilibrium, only the two mechanisms that increase the average grainsize are allowed by the second law of thermodynamics. The first one is a diffusive mass transport

  14. A theoretical microbial contamination model for a human Mars mission

    NASA Astrophysics Data System (ADS)

    Lupisella, Mark Lewis

    Contamination from a human presence on Mars could significantly compromise the search for extraterrestrial life. In particular, the difficulties in controlling microbial contamination, the potential for terrestrial microbes to grow, evolve, compete, and modify the Martian environment, and the likely microbial nature of putative Martian life, make microbial contamination worthy of focus as we begin to plan for a human mission to Mars. This dissertation describes a relatively simple theoretical model that can be used to explore how microbial contamination from a human Mars mission might survive and grow in the Martian soil environment surrounding a habitat. A user interface has been developed to allow a general practitioner to choose values and functions for almost all parameters ranging from the number of astronauts to the half-saturation constants for microbial growth. Systematic deviations from a baseline set of parameter values are explored as potential plausible scenarios for the first human Mars missions. The total viable population and population density are the primary state variables of interest, but other variables such as the total number of births and total dead and viable microbes are also tracked. The general approach was to find the most plausible parameter value combinations that produced a population density of 1 microbe/cm3 or greater, a threshold that was used to categorize the more noteworthy populations for subsequent analysis. Preliminary assessments indicate that terrestrial microbial contamination resulting from leakage from a limited human mission (perhaps lasting up to 5 months) will not likely become a problematic population in the near-term as long as reasonable contamination control measures are implemented (for example, a habitat leak rate no greater than 1% per hour). However, there appear to be plausible, albeit unlikely, scenarios that could cause problematic populations, depending in part on (a) the initial survival fraction and

  15. Presenting a Theoretical Model of Four Conceptions of Civic Education

    ERIC Educational Resources Information Center

    Cohen, Aviv

    2010-01-01

    This conceptual study will question the ways different epistemological conceptions of citizenship and education influence the characteristics of civic education. While offering a new theoretical framework, the different undercurrent conceptions that lay at the base of the civic education process shall be brought forth. With the use of the method…

  16. An Elaboration Likelihood Model Based Longitudinal Analysis of Attitude Change during the Process of IT Acceptance via Education Program

    ERIC Educational Resources Information Center

    Lee, Woong-Kyu

    2012-01-01

    The principal objective of this study was to gain insight into attitude changes occurring during IT acceptance from the perspective of elaboration likelihood model (ELM). In particular, the primary target of this study was the process of IT acceptance through an education program. Although the Internet and computers are now quite ubiquitous, and…

  17. An Investigation of Employees' Use of E-Learning Systems: Applying the Technology Acceptance Model

    ERIC Educational Resources Information Center

    Lee, Yi-Hsuan; Hsieh, Yi-Chuan; Chen, Yen-Hsun

    2013-01-01

    The purpose of this study is to apply the technology acceptance model to examine the employees' attitudes and acceptance of electronic learning (e-learning) systems in organisations. This study examines four factors (organisational support, computer self-efficacy, prior experience and task equivocality) that are believed to influence…

  18. An Exploration of Student Internet Use in India: The Technology Acceptance Model and the Theory of Planned Behaviour

    ERIC Educational Resources Information Center

    Fusilier, Marcelline; Durlabhji, Subhash

    2005-01-01

    Purpose: The purpose of this paper is to explore behavioral processes involved in internet technology acceptance and use with a sample in India, a developing country that can potentially benefit from greater participation in the web economy. Design/methodology/approach - User experience was incorporated into the technology acceptance model (TAM)…

  19. Factors of adoption of mobile information technology by homecare nurses: a technology acceptance model 2 approach.

    PubMed

    Zhang, Huiying; Cocosila, Mihail; Archer, Norm

    2010-01-01

    Pervasive healthcare support through mobile information technology solutions is playing an increasing role in the attempt to improve healthcare and reduce costs. Despite the apparent attractiveness, many mobile applications have failed or have not been implemented as predicted. Among factors possibly leading to such outcomes, technology adoption is a key problem. This must be investigated early in the development process because healthcare is a particularly sensitive area with vital social implications. Moreover, it is important to investigate technology acceptance using the support of scientific tools validated for relevant information systems research. This article presents an empirical study based on the Technology Acceptance Model 2 in mobile homecare nursing. The study elicited the perceptions of 91 Canadian nurses who used personal digital assistants for 1 month in their daily activities. A partial least squares modeling data analysis revealed that nurse's perception of usefulness is the main factor in the adoption of mobile technology, having subjective norm and image within the organization as significant antecedents. Overall, this study was the first attempt at investigating scientifically, through a pertinent information systems research model, user adoption of mobile systems by homecare nursing personnel.

  20. Testing the Electronic Personal Health Record Acceptance Model by Nurses for Managing Their Own Health

    PubMed Central

    Trinkoff, A.M.; Storr, C.L.; Wilson, M.L.; Gurses, A.P.

    2015-01-01

    Summary Background To our knowledge, no evidence is available on health care professionals’ use of electronic personal health records (ePHRs) for their health management. We therefore focused on nurses’ personal use of ePHRs using a modified technology acceptance model. Objectives To examine (1) the psychometric properties of the ePHR acceptance model, (2) the associations of perceived usefulness, ease of use, data privacy and security protection, and perception of self as health-promoting role models to nurses’ own ePHR use, and (3) the moderating influences of age, chronic illness and medication use, and providers’ use of electronic health record (EHRs) on the associations between the ePHR acceptance constructs and ePHR use. Methods A convenience sample of registered nurses, those working in one of 12 hospitals in the Maryland and Washington, DC areas and members of the nursing informatics community (AMIA and HIMSS), were invited to respond to an anonymous online survey; 847 responded. Multiple logistic regression identified associations between the model constructs and ePHR use, and the moderating effect. Results Overall, ePHRs were used by 47%. Sufficient reliability for all scales was found. Three constructs were significantly related to nurses’ own ePHR use after adjusting for covariates: usefulness, data privacy and security protection, and health-promoting role model. Nurses with providers that used EHRs who perceived a higher level of data privacy and security protection had greater odds of ePHR use than those whose providers did not use EHRs. Older nurses with a higher self-perception as health-promoting role models had greater odds of ePHR use than younger nurses. Conclusions Nurses who use ePHRs for their personal health might promote adoption by the general public by serving as health-promoting role models. They can contribute to improvements in patient education and ePHR design, and serve as crucial resources when working with their

  1. Modelling drying kinetics of thyme (Thymus vulgaris L.): theoretical and empirical models, and neural networks.

    PubMed

    Rodríguez, J; Clemente, G; Sanjuán, N; Bon, J

    2014-01-01

    The drying kinetics of thyme was analyzed by considering different conditions: air temperature of between 40°C  and 70°C , and air velocity of 1 m/s. A theoretical diffusion model and eight different empirical models were fitted to the experimental data. From the theoretical model application, the effective diffusivity per unit area of the thyme was estimated (between 3.68 × 10(-5) and 2.12 × 10 (-4) s(-1)). The temperature dependence of the effective diffusivity was described by the Arrhenius relationship with activation energy of 49.42 kJ/mol. Eight different empirical models were fitted to the experimental data. Additionally, the dependence of the parameters of each model on the drying temperature was determined, obtaining equations that allow estimating the evolution of the moisture content at any temperature in the established range. Furthermore, artificial neural networks were developed and compared with the theoretical and empirical models using the percentage of the relative errors and the explained variance. The artificial neural networks were found to be more accurate predictors of moisture evolution with VAR ≥ 99.3% and ER ≤ 8.7%.

  2. Modelling drying kinetics of thyme (Thymus vulgaris L.): theoretical and empirical models, and neural networks.

    PubMed

    Rodríguez, J; Clemente, G; Sanjuán, N; Bon, J

    2014-01-01

    The drying kinetics of thyme was analyzed by considering different conditions: air temperature of between 40°C  and 70°C , and air velocity of 1 m/s. A theoretical diffusion model and eight different empirical models were fitted to the experimental data. From the theoretical model application, the effective diffusivity per unit area of the thyme was estimated (between 3.68 × 10(-5) and 2.12 × 10 (-4) s(-1)). The temperature dependence of the effective diffusivity was described by the Arrhenius relationship with activation energy of 49.42 kJ/mol. Eight different empirical models were fitted to the experimental data. Additionally, the dependence of the parameters of each model on the drying temperature was determined, obtaining equations that allow estimating the evolution of the moisture content at any temperature in the established range. Furthermore, artificial neural networks were developed and compared with the theoretical and empirical models using the percentage of the relative errors and the explained variance. The artificial neural networks were found to be more accurate predictors of moisture evolution with VAR ≥ 99.3% and ER ≤ 8.7%. PMID:23733820

  3. Theoretical Model to Explain Excess of Quasiparticles in Superconductors.

    PubMed

    Bespalov, Anton; Houzet, Manuel; Meyer, Julia S; Nazarov, Yuli V

    2016-09-01

    Experimentally, the concentration of quasiparticles in gapped superconductors always largely exceeds the equilibrium one at low temperatures. Since these quasiparticles are detrimental for many applications, it is important to understand theoretically the origin of the excess. We demonstrate in detail that the dynamics of quasiparticles localized at spatial fluctuations of the gap edge becomes exponentially slow. This gives rise to the observed excess in the presence of a vanishingly weak nonequilibrium agent. PMID:27661716

  4. Electronic Health Record Patient Portal Adoption by Health Care Consumers: An Acceptance Model and Survey

    PubMed Central

    2016-01-01

    Background The future of health care delivery is becoming more citizen centered, as today’s user is more active, better informed, and more demanding. Worldwide governments are promoting online health services, such as electronic health record (EHR) patient portals and, as a result, the deployment and use of these services. Overall, this makes the adoption of patient-accessible EHR portals an important field to study and understand. Objective The aim of this study is to understand the factors that drive individuals to adopt EHR portals. Methods We applied a new adoption model using, as a starting point, Ventkatesh's Unified Theory of Acceptance and Use of Technology in a consumer context (UTAUT2) by integrating a new construct specific to health care, a new moderator, and new relationships. To test the research model, we used the partial least squares (PLS) causal modelling approach. An online questionnaire was administrated. We collected 360 valid responses. Results The statistically significant drivers of behavioral intention are performance expectancy (beta=.200; t=3.619), effort expectancy (beta=.185; t=2.907), habit (beta=.388; t=7.320), and self-perception (beta=.098; t=2.285). The predictors of use behavior are habit (beta=0.206; t=2.752) and behavioral intention (beta=0.258; t=4.036). The model explained 49.7% of the variance in behavioral intention and 26.8% of the variance in use behavior. Conclusions Our research helps to understand the desired technology characteristics of EHR portals. By testing an information technology acceptance model, we are able to determine what is more valued by patients when it comes to deciding whether to adopt EHR portals or not. The inclusion of specific constructs and relationships related to the health care consumer area also had a significant impact on understanding the adoption of EHR portals. PMID:26935646

  5. The Synthesis of a Theoretical Model of Student Attrition.

    ERIC Educational Resources Information Center

    Bean, John P.

    Models that have appeared in the student attrition literature in the past decade and behavioral models from the social sciences that may help explain the dropout process are examined, and an attempt is made to synthesize a causal model of student attrition. The models of Tinto, Spady, and Rootman in the area of student attrition, and models of…

  6. Intention to use and actual use of electronic information resources: further exploring Technology Acceptance Model (TAM).

    PubMed

    Tao, Donghua

    2009-11-14

    Following up a previous study that examined public health students' intention to use e-resources for completing research paper assignments, the present study proposed two models to investigate whether or not public health students actually used the e-resources they intended to use and whether or not the determinants of intention to use predict actual use of e-resources. Focus groups and pre- and post-questionnaires were used to collect data. Descriptive analysis, data screening, and Structural Equation Modeling (SEM) techniques were used for data analysis. The study found that the determinants of intention-to-use significantly predict actual use behavior. Direct impact of perceived usefulness and indirect impact of perceived ease of use to both behavior intention and actual behavior indicated the importance of ease of use at the early stage of technology acceptance. Non-significant intention-behavior relationship prompted thoughts on the measurement of actual behavior and multidimensional characteristics of the intention construct.

  7. A Model of Resource Allocation in Public School Districts: A Theoretical and Empirical Analysis.

    ERIC Educational Resources Information Center

    Chambers, Jay G.

    This paper formulates a comprehensive model of resource allocation in a local public school district. The theoretical framework specified could be applied equally well to any number of local public social service agencies. Section 1 develops the theoretical model describing the process of resource allocation. This involves the determination of the…

  8. Improving Mathematics Instruction through Lesson Study: A Theoretical Model and North American Case

    ERIC Educational Resources Information Center

    Lewis, Catherine C.; Perry, Rebecca R.; Hurd, Jacqueline

    2009-01-01

    This article presents a theoretical model of lesson study, an approach to instructional improvement that originated in Japan. The theoretical model includes four lesson study features (investigation, planning, research lesson, and reflection) and three pathways through which lesson study improves instruction: changes in teachers' knowledge and…

  9. Development of Children's Creative Visual Imagination: A Theoretical Model and Enhancement Programmes

    ERIC Educational Resources Information Center

    Dziedziewicz, Dorota; Karwowski, Maciej

    2015-01-01

    This paper presents a new theoretical model of creative imagination and its applications in early education. The model sees creative imagination as composed of three inter-related components: vividness of images, their originality, and the level of transformation of imageries. We explore the theoretical and practical consequences of this new…

  10. A theoretical model of phase changes of a klystron due to variation of operating parameters

    NASA Technical Reports Server (NTRS)

    Kupiszewski, A.

    1980-01-01

    A mathematical model for phase changes of the VA-876 CW klystron amplifier output is presented and variations of several operating parameters are considered. The theoretical approach to the problem is based upon a gridded gap modeling with inclusion of a second order correction term so that actual gap geometry is reflected in the formulation. Physical measurements are contrasted to theoretical calculations.

  11. A theoretical model of barriers having inhomogeneous impedance surfaces.

    PubMed

    Wang, Xu; Wang, Xiaonan; Yu, Wuzhou; Jiang, Zaixiu; Mao, Dongxing

    2016-03-01

    When barriers are placed in parallel on opposite sides of a source, their performance deteriorates markedly. However, barriers made from materials of inhomogeneous impedance eliminate this drawback by altering the behavior of sound as it undergoes multiple reflections between the barriers. In this paper, a theoretical approach is carried out to estimate the performance of the proposed barriers. By combining the ray-tracing method and sound diffraction theory, the existence of different ray paths between the proposed barriers is revealed. Compared to conventional rigid-walled barriers, barriers having inhomogeneous surfaces may have the potential to be widely used in environmental noise control. PMID:27036289

  12. On theoretical and experimental modeling of metabolism forming in prebiotic systems

    NASA Astrophysics Data System (ADS)

    Bartsev, S. I.; Mezhevikin, V. V.

    Recently searching for extraterrestrial life attracts more and more attention However the searching hardly can be effective without sufficiently universal concept of life origin which incidentally tackles a problem of origin of life on the Earth A concept of initial stages of life origin including origin of prebiotic metabolism is stated in the paper Suggested concept eliminates key difficulties in the problem of life origin and allows experimental verification of it According to the concept the predecessor of living beings has to be sufficiently simple to provide non-zero probability of self-assembling during short in geological or cosmic scale time In addition the predecessor has to be capable of autocatalysis and further complication evolution A possible scenario of initial stage of life origin which can be realized both on other planets and inside experimental facility is considered In the scope of the scenario a theoretical model of multivariate oligomeric autocatalyst coupled with phase-separated particle is presented Results of computer simulation of possible initial stage of chemical evolution are shown Conducted estimations show the origin of autocatalytic oligomeric phase-separated system is possible at reasonable values of kinetic parameters of involved chemical reactions in a small-scale flow reactor Accepted statements allowing to eliminate key problems of life origin imply important consequence -- organisms emerged out of the Earth or inside a reactor have to be based on another different from terrestrial biochemical

  13. Positive Psychological Interventions for Patients with Type 2 Diabetes: Rationale, Theoretical Model, and Intervention Development

    PubMed Central

    Huffman, Jeff C.; DuBois, Christina M.; Millstein, Rachel A.; Celano, Christopher M.; Wexler, Deborah

    2015-01-01

    Most patients with type 2 diabetes (T2D) have suboptimal adherence to recommended diet, physical activity, and/or medication. Current approaches to improve health behaviors in T2D have been variably effective, and successful interventions are often complex and intensive. It is therefore vital to develop interventions that are simple, well-accepted, and applicable to a wide range of patients who suffer from T2D. One approach may be to boost positive psychological states, such as positive affect or optimism, as these constructs have been prospectively and independently linked to improvements in health behaviors. Positive psychology (PP) interventions, which utilize systematic exercises to increase optimism, well-being, and positive affect, consistently increase positive states and are easily delivered to patients with chronic illnesses. However, to our knowledge, PP interventions have not been formally tested in T2D. In this paper, we review a theoretical model for the use of PP interventions to target health behaviors in T2D, describe the structure and content of a PP intervention for T2D patients, and describe baseline data from a single-arm proof-of-concept (N = 15) intervention study in T2D patients with or without depression. We also discuss how PP interventions could be combined with motivational interviewing (MI) interventions to provide a blended psychological-behavioral approach. PMID:26064980

  14. Acceptance and commitment therapy and contextual behavioral science: examining the progress of a distinctive model of behavioral and cognitive therapy.

    PubMed

    Hayes, Steven C; Levin, Michael E; Plumb-Vilardaga, Jennifer; Villatte, Jennifer L; Pistorello, Jacqueline

    2013-06-01

    A number of recent authors have compared acceptance and commitment therapy (ACT) and traditional cognitive behavior therapy (CBT). The present article describes ACT as a distinct and unified model of behavior change, linked to a specific strategy of scientific development, which we term "contextual behavioral science." We outline the empirical progress of ACT and describe its distinctive development strategy. A contextual behavioral science approach is an inductive attempt to build more adequate psychological systems based on philosophical clarity; the development of basic principles and theories; the development of applied theories linked to basic ones; techniques and components linked to these processes and principles; measurement of theoretically key processes; an emphasis on mediation and moderation in the analysis of applied impact; an interest in effectiveness, dissemination, and training; empirical testing of the research program across a broad range of areas and levels of analysis; and the creation of a more effective scientific and clinical community. We argue that this is a reasonable approach, focused on long-term progress, and that in broad terms it seems to be working. ACT is not hostile to traditional CBT, and is not directly buoyed by whatever weaknesses traditional CBT may have. ACT should be measured at least in part against its own goals as specified by its own developmental strategy.

  15. Comparing Cognitive, Metacognitive, and Acceptance and Commitment Therapy Models of Depression: a Longitudinal Study Survey.

    PubMed

    Ruiz, Francisco J; Odriozola-González, Paula

    2015-06-16

    This study analyzed the interrelationships between key constructs of cognitive therapy (CT; depressogenic schemas), metacognitive therapy (MCT; dysfunctional metacognitive beliefs), and acceptance and commitment therapy (ACT; psychological inflexibility) in the prediction of depressive symptoms. With a lapse of nine months, 106 nonclinical participants responded twice to an anonymous online survey containing the following questionnaires: the Depression subscale of the Depression Anxiety and Stress Scales (DASS), the Dysfunctional Attitude Scale Revised (DAS-R), the Positive beliefs, Negative beliefs and Need to control subscales of the Metacognitions Questionnaire-30 (MCQ-30), and the Acceptance and Action Questionnaire - II (AAQ-II). Results showed that when controlling for baseline levels of depressive symptoms and demographic variables, psychological inflexibility longitudinally mediated the effect of depressogenic schemas (path ab = .023, SE = .010; 95% BC CI [.008, .048]) and dysfunctional metacognitive beliefs on depressive symptoms (positive metacognitive beliefs: path ab = .052, SE = .031; 95% BC CI [.005, .134]; negative metacognitive beliefs: path ab = .087, SE = .049; 95% BC CI [.016, .214]; need to control: path ab = .087, SE = .051; 95% BC CI [.013, .220]). Results are discussed emphasizing the role of psychological inflexibility in the CT and MCT models of depression.

  16. Theoretical modelling of exchange interactions in metal-phthalocyanines

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Fisher, Andrew; Harrison, Nic; Serri, Michele; Wu, Zhenlin; Heutz, Sandrine; Jones, Tim; Aeppli, Gabriel

    2012-02-01

    The theoretical understanding of exchange interactions in organics provides a key foundation for quantum molecular magnetism. Recent SQUID magnetometry of a well know organic semiconductor, copper-phthalocyanine [1,2] (CuPc) shows that it forms quasi-one-dimensional spin chains. Green's function perturbation theory calculation [3] is used to find the dominant exchange mechanism. Hybrid density functional theory simulations [4] give a quantitative insight to exchange interactions and electronic structures. Both calculations are performed for different stacking and sliding angles for lithium-Pc, cobalt-Pc, chromium-Pc, and copper-Pc. The exchange interactions depend strongly on stacking angles, but weakly on sliding angles. Our results qualitatively agree with the experiments, and remarkably α-cobalt-Pc has a very large exchange above liquid-Nitrogen temperature. Our theoretical predictions on the exchange interactions can guide experimentalists to design novel organic semiconductors. [0pt] [1] S. Heutz, et. al., Adv. Mat., 19, 3618 (2007) [2] Hai Wang, et. al., ACS Nano, 4, 3921 (2010) [3] Wei Wu, et. al., Phys. Rev. B 77, 184403 (2008) [4] Wei Wu, et. al., Phys. Rev. B 84, 024427 (2011)

  17. Re-examining the role of attitude in information system acceptance: a model from the satisfaction-dissatisfaction perspective

    NASA Astrophysics Data System (ADS)

    Guo, Bin; Zhou, Shasha

    2016-05-01

    This study attempts to re-examine the role of attitude in voluntary information system (IS) acceptance and usage, which has often been discounted in the previous technology acceptance research. We extend the unidimensional view of attitude into a bidimensional one, because of the simultaneous existence of both positive and negative evaluation towards IS in technology acceptance behaviour. In doing so, attitude construct is divided into two components: satisfaction as the positive attitudinal component and dissatisfaction as the negative attitudinal component. We argue that satisfaction and dissatisfaction will interactively affect technology usage intention. Besides, we explore the predictors of satisfaction and dissatisfaction based on the disconfirmation theory. Empirical results from a longitudinal study on bulletin board system (BBS) usage confirm the interaction effect of satisfaction and dissatisfaction on usage intention. Moreover, perceived task-related value has a significant effect on satisfaction, while perceived personal value has a significant effect on dissatisfaction. We also discuss the theoretical and managerial implications of our findings.

  18. Consumer acceptance and stability of spray dried betanin in model juices.

    PubMed

    Kaimainen, Mika; Laaksonen, Oskar; Järvenpää, Eila; Sandell, Mari; Huopalahti, Rainer

    2015-11-15

    Spray dried beetroot powder was used to colour model juices, and the consumer acceptance of the juices and stability of the colour during storage at 60 °C, 20 °C, 4 °C, and -20 °C were studied. The majority of the consumers preferred the model juices coloured with anthocyanins or beetroot extract over model juices coloured with spray dried beetroot powder. The consumers preferred more intensely coloured samples over lighter samples. Spray dried betanin samples were described as 'unnatural' and 'artificial' whereas the colour of beetroot extract was described more 'natural' and 'real juice'. No beetroot-derived off-odours or off-flavours were perceived in the model juices coloured with beetroot powder. Colour stability in model juices was greatly dependent on storage temperature with better stability at lower temperatures. Colour stability in the spray dried powder was very good at 20 °C. Betacyanins from beetroot could be a potential colourant for food products that are stored cold. PMID:25977043

  19. Consumer acceptance and stability of spray dried betanin in model juices.

    PubMed

    Kaimainen, Mika; Laaksonen, Oskar; Järvenpää, Eila; Sandell, Mari; Huopalahti, Rainer

    2015-11-15

    Spray dried beetroot powder was used to colour model juices, and the consumer acceptance of the juices and stability of the colour during storage at 60 °C, 20 °C, 4 °C, and -20 °C were studied. The majority of the consumers preferred the model juices coloured with anthocyanins or beetroot extract over model juices coloured with spray dried beetroot powder. The consumers preferred more intensely coloured samples over lighter samples. Spray dried betanin samples were described as 'unnatural' and 'artificial' whereas the colour of beetroot extract was described more 'natural' and 'real juice'. No beetroot-derived off-odours or off-flavours were perceived in the model juices coloured with beetroot powder. Colour stability in model juices was greatly dependent on storage temperature with better stability at lower temperatures. Colour stability in the spray dried powder was very good at 20 °C. Betacyanins from beetroot could be a potential colourant for food products that are stored cold.

  20. Information-theoretic model comparison unifies saliency metrics

    PubMed Central

    Kümmerer, Matthias; Wallis, Thomas S. A.; Bethge, Matthias

    2015-01-01

    Learning the properties of an image associated with human gaze placement is important both for understanding how biological systems explore the environment and for computer vision applications. There is a large literature on quantitative eye movement models that seeks to predict fixations from images (sometimes termed “saliency” prediction). A major problem known to the field is that existing model comparison metrics give inconsistent results, causing confusion. We argue that the primary reason for these inconsistencies is because different metrics and models use different definitions of what a “saliency map” entails. For example, some metrics expect a model to account for image-independent central fixation bias whereas others will penalize a model that does. Here we bring saliency evaluation into the domain of information by framing fixation prediction models probabilistically and calculating information gain. We jointly optimize the scale, the center bias, and spatial blurring of all models within this framework. Evaluating existing metrics on these rephrased models produces almost perfect agreement in model rankings across the metrics. Model performance is separated from center bias and spatial blurring, avoiding the confounding of these factors in model comparison. We additionally provide a method to show where and how models fail to capture information in the fixations on the pixel level. These methods are readily extended to spatiotemporal models of fixation scanpaths, and we provide a software package to facilitate their use. PMID:26655340

  1. Information-theoretic model comparison unifies saliency metrics.

    PubMed

    Kümmerer, Matthias; Wallis, Thomas S A; Bethge, Matthias

    2015-12-29

    Learning the properties of an image associated with human gaze placement is important both for understanding how biological systems explore the environment and for computer vision applications. There is a large literature on quantitative eye movement models that seeks to predict fixations from images (sometimes termed "saliency" prediction). A major problem known to the field is that existing model comparison metrics give inconsistent results, causing confusion. We argue that the primary reason for these inconsistencies is because different metrics and models use different definitions of what a "saliency map" entails. For example, some metrics expect a model to account for image-independent central fixation bias whereas others will penalize a model that does. Here we bring saliency evaluation into the domain of information by framing fixation prediction models probabilistically and calculating information gain. We jointly optimize the scale, the center bias, and spatial blurring of all models within this framework. Evaluating existing metrics on these rephrased models produces almost perfect agreement in model rankings across the metrics. Model performance is separated from center bias and spatial blurring, avoiding the confounding of these factors in model comparison. We additionally provide a method to show where and how models fail to capture information in the fixations on the pixel level. These methods are readily extended to spatiotemporal models of fixation scanpaths, and we provide a software package to facilitate their use.

  2. College Students Solving Chemistry Problems: A Theoretical Model of Expertise

    ERIC Educational Resources Information Center

    Taasoobshirazi, Gita; Glynn, Shawn M.

    2009-01-01

    A model of expertise in chemistry problem solving was tested on undergraduate science majors enrolled in a chemistry course. The model was based on Anderson's "Adaptive Control of Thought-Rational" (ACT-R) theory. The model shows how conceptualization, self-efficacy, and strategy interact and contribute to the successful solution of quantitative,…

  3. Building a Theoretical Model of Metacognitive Processes in Complex Modeling Activities: A Window into the Development of Students' Metacognitive Abilities

    ERIC Educational Resources Information Center

    Kim, Young Rae

    2013-01-01

    A theoretical model of metacognition in complex modeling activities has been developed based on existing frameworks, by synthesizing the re-conceptualization of metacognition at multiple levels by looking at the three sources that trigger metacognition. Using the theoretical model as a framework, this study was designed to explore how students'…

  4. [Nursing practice based on theoretical models: a qualitative study of nurses' perception].

    PubMed

    Amaducci, Giovanna; Iemmi, Marina; Prandi, Marzia; Saffioti, Angelina; Carpanoni, Marika; Mecugni, Daniela

    2013-01-01

    Many faculty argue that theory and theorizing are closely related to the clinical practice, that the disciplinary knowledge grows, more relevantly, from the specific care context in which it takes place and, moreover, that knowledge does not proceed only by the application of general principles of the grand theories to specific cases. Every nurse, in fact, have  a mental model, of what may or may not be aware, that motivate and substantiate every action and choice of career. The study describes what the nursing theoretical model is; the mental model and the tacit  knowledge underlying it. It identifies the explicit theoretical model of the professional group that rapresents nursing partecipants, aspects of continuity with the theoretical model proposed by this degree course in Nursing.. Methods Four focus groups were made which were attended by a total of 22 nurses, rapresentatives of almost every Unit of Reggio Emilia Hospital's. We argue that the theoretical nursing model of each professional group is the result of tacit knowledge, which help to define the personal mental model, and the theoretical model, which explicitly underlying theoretical content learned applied consciously and reverted to / from nursing practice. Reasoning on the use of theory in practice has allowed us to give visibility to a theoretical model explicitly nursing authentically oriented to the needs of the person, in all its complexity in specific contexts.

  5. Social Competence in Peer-Accepted Children with and without Learning Disabilities.

    ERIC Educational Resources Information Center

    Brown, Andrea; Heath, Nancy

    This paper examines the social-emotional functioning of peer-accepted children with learning disabilities (LD) within the theoretical framework of the Vaughn and Hogan model of social competence. Holding peer acceptance constant within the model (i.e. only peer accepted children participated in the study), teacher and self-reported characteristics…

  6. Theoretical and experimental modeling of a rail gun accelerator

    NASA Astrophysics Data System (ADS)

    Zheleznyj, V. B.; Zagorskij, A. V.; Katsnel'Son, S. S.; Kudryavtsev, A. V.; Plekhanov, A. V.

    1993-04-01

    Results of a series of experiments in the acceleration of macrobodies are analyzed using an integral model of a current arc and a quasi-1D magnetic gasdynamic model. The integral model uses gasdynamic equations averaged by the size of a plasma pump and equations based on the second Kirchhoff's law for electrical current. The quasi-1D model is based on 1D magnetic gasdynamic equations for mean values of density, pressure, velocity, and internal power. Electromagnetic parameters are determined from Maxwell integral equations. It is concluded that the proposed models take into account the major mechanisms of momentum loss and are capable of adequately describing electromagnetic rail accelerators.

  7. Psychosocial stress and prostate cancer: a theoretical model.

    PubMed

    Ellison, G L; Coker, A L; Hebert, J R; Sanderson, S M; Royal, C D; Weinrich, S P

    2001-01-01

    African-American men are more likely to develop and die from prostate cancer than are European-American men; yet, factors responsible for the racial disparity in incidence and mortality have not been elucidated. Socioeconomic disadvantage is more prevalent among African-American than among European-American men. Socioeconomic disadvantage can lead to psychosocial stress and may be linked to negative lifestyle behaviors. Regardless of socioeconomic position, African-American men routinely experience racism-induced stress. We propose a theoretical framework for an association between psychosocial stress and prostate cancer. Within the context of history and culture, we further propose that psychosocial stress may partially explain the variable incidence of prostate cancer between these diverse groups. Psychosocial stress may negatively impact the immune system leaving the individual susceptible to malignancies. Behavioral responses to psychosocial stress are amenable to change. If psychosocial stress is found to negatively impact prostate cancer risk, interventions may be designed to modify reactions to environmental demands.

  8. A graph theoretical perspective of a drug abuse epidemic model

    NASA Astrophysics Data System (ADS)

    Nyabadza, F.; Mukwembi, S.; Rodrigues, B. G.

    2011-05-01

    A drug use epidemic can be represented by a finite number of states and transition rules that govern the dynamics of drug use in each discrete time step. This paper investigates the spread of drug use in a community where some users are in treatment and others are not in treatment, citing South Africa as an example. In our analysis, we consider the neighbourhood prevalence of each individual, i.e., the proportion of the individual’s drug user contacts who are not in treatment amongst all of his or her contacts. We introduce parameters α∗, β∗ and γ∗, depending on the neighbourhood prevalence, which govern the spread of drug use. We examine how changes in α∗, β∗ and γ∗ affect the system dynamics. Simulations presented support the theoretical results.

  9. Theoretical modelling of the semiconductor-electrolyte interface

    NASA Astrophysics Data System (ADS)

    Schelling, Patrick Kenneth

    We have developed tight-binding models of transition metal oxides. In contrast to many tight-binding models, these models include a description of electron-electron interactions. After parameterizing to bulk first-principles calculations, we demonstrated the transferability of the model by calculating atomic and electronic structure of rutile surfaces, which compared well with experiment and first-principles calculations. We also studied the structure of twist grain boundaries in rutile. Molecular dynamics simulations using the model were also carried out to describe polaron localization. We have also demonstrated that tight-binding models can be constructed to describe metallic systems. The computational cost tight-binding simulations was greatly reduced by incorporating O(N) electronic structure methods. We have also interpreted photoluminesence experiments on GaAs electrodes in contact with an electrolyte using drift-diffusion models. Electron transfer velocities were obtained by fitting to experimental results.

  10. Where there's smoke: Cigarette use, social acceptability, and spatial approaches to multilevel modeling.

    PubMed

    O'Connell, Heather A

    2015-09-01

    I contribute to understandings of how context is related to individual outcomes by assessing the added value of combining multilevel and spatial modeling techniques. This methodological approach leads to substantive contributions to the smoking literature, including improved clarity on the central contextual factors and the examination of one manifestation of the social acceptability hypothesis. For this analysis I use restricted-use natality data from the Vital Statistics, and county-level data from the 2005-9 ACS. Critically, the results suggest that spatial considerations are still relevant in a multilevel framework. In addition, I argue that spatial processes help explain the relationships linking racial/ethnic minority concentration to lower overall odds of smoking. PMID:26188587

  11. WHERE THERE’S SMOKE: CIGARETTE USE, SOCIAL ACCEPTABILITY, AND SPATIAL APPROACHES TO MULTILEVEL MODELING

    PubMed Central

    O’Connell, Heather A.

    2015-01-01

    I contribute to understandings of how context is related to individual outcomes by assessing the added value of combining multilevel and spatial modeling techniques. This methodological approach leads to substantive contributions to the smoking literature, including improved clarity on the central contextual factors and the examination of one manifestation of the social acceptability hypothesis. For this analysis I use restricted-use natality data from the Vital Statistics, and county-level data from the 2005–9 ACS. Critically, the results suggest that spatial considerations are still relevant in a multilevel framework. In addition, I argue that spatial processes help explain the relationships linking racial/ethnic minority concentration to lower overall odds of smoking. PMID:26188587

  12. Theoretical development of a simplified wheelset model to evaluate collision-induced derailments of rolling stock

    NASA Astrophysics Data System (ADS)

    Koo, Jeong Seo; Choi, Se Young

    2012-06-01

    A theoretical method is proposed to predict and evaluate collision-induced derailments of rolling stock by using a simplified wheelset model and is verified with dynamic simulations. Because the impact forces occurring during collision are transmitted from the car body to the bogies and axles through suspensions, rolling stock leads to derailment as a result of the combination of horizontal and vertical impact forces applied to the axle and a simplified wheelset model enforced at the axle can be used to theoretically formulate derailment behaviors. The derailment type depends on the combination of the horizontal and vertical forces, the flange angle and the friction coefficient. According to collision conditions, wheel-climb, wheel-lift or roll-over derailment can occur between the wheel and the rail. In this theoretical derailment model of a simplified wheelset, the derailment types are classified as Slip-up, Slip/roll-over, Climb-up, Climb/roll-over and pure Roll-over according to the derailment mechanisms between the wheel and the rail and the theoretical conditions needed to generate each derailment mechanism are proposed. The theoretical wheelset model is verified by dynamic simulation and its applicability is demonstrated by comparing the simulation results of the theoretical wheelset model with those of an actual wheelset model. The theoretical derailment wheelset model is in good agreement with the virtual testing model simulation for a collision-induced derailment of rolling stock.

  13. Theoretical Models for Application in School Health Education Research.

    ERIC Educational Resources Information Center

    Parcel, Guy S.

    1984-01-01

    Selected behavioral change theories, multiple theory models, and teaching models that may be useful to research studies in health education are examined in this article. A brief outline of applications of theory for the field of school health education is offered. (Author/DF)

  14. Raindrop size distribution: Fitting performance of common theoretical models

    NASA Astrophysics Data System (ADS)

    Adirosi, E.; Volpi, E.; Lombardo, F.; Baldini, L.

    2016-10-01

    Modelling raindrop size distribution (DSD) is a fundamental issue to connect remote sensing observations with reliable precipitation products for hydrological applications. To date, various standard probability distributions have been proposed to build DSD models. Relevant questions to ask indeed are how often and how good such models fit empirical data, given that the advances in both data availability and technology used to estimate DSDs have allowed many of the deficiencies of early analyses to be mitigated. Therefore, we present a comprehensive follow-up of a previous study on the comparison of statistical fitting of three common DSD models against 2D-Video Distrometer (2DVD) data, which are unique in that the size of individual drops is determined accurately. By maximum likelihood method, we fit models based on lognormal, gamma and Weibull distributions to more than 42.000 1-minute drop-by-drop data taken from the field campaigns of the NASA Ground Validation program of the Global Precipitation Measurement (GPM) mission. In order to check the adequacy between the models and the measured data, we investigate the goodness of fit of each distribution using the Kolmogorov-Smirnov test. Then, we apply a specific model selection technique to evaluate the relative quality of each model. Results show that the gamma distribution has the lowest KS rejection rate, while the Weibull distribution is the most frequently rejected. Ranking for each minute the statistical models that pass the KS test, it can be argued that the probability distributions whose tails are exponentially bounded, i.e. light-tailed distributions, seem to be adequate to model the natural variability of DSDs. However, in line with our previous study, we also found that frequency distributions of empirical DSDs could be heavy-tailed in a number of cases, which may result in severe uncertainty in estimating statistical moments and bulk variables.

  15. Theoretical Tools in Modeling Communication and Language Dynamics

    NASA Astrophysics Data System (ADS)

    Loreto, Vittorio

    Statistical physics has proven to be a very fruitful framework to describe phenomena outside the realm of traditional physics. In social phenomena, the basic constituents are not particles but humans and every individual interacts with a limited number of peers, usually negligible compared to the total number of people in the system. In spite of that, human societies are characterized by stunning global regularities that naturally call for a statistical physics approach to social behavior, i.e., the attempt to understand regularities at large scale as collective effects of the interaction among single individuals, considered as relatively simple entities. This is the paradigm of Complex Systems: an assembly of many interacting (and simple) units whose collective behavior is not trivially deducible from the knowledge of the rules governing their mutual interactions. In this chapter we review the main theoretical concepts and tools that physics can borrow to socially-motivated problems. Despite their apparent diversity, most research lines in social dynamics are actually closely connected from the point of view of both the methodologies employed and, more importantly, of the general phenomenological questions, e.g., what are the fundamental interaction mechanisms leading to the emergence of consensus on an issue, a shared culture, a common language or a collective motion?

  16. Psychosocial stress and prostate cancer: a theoretical model.

    PubMed

    Ellison, G L; Coker, A L; Hebert, J R; Sanderson, S M; Royal, C D; Weinrich, S P

    2001-01-01

    African-American men are more likely to develop and die from prostate cancer than are European-American men; yet, factors responsible for the racial disparity in incidence and mortality have not been elucidated. Socioeconomic disadvantage is more prevalent among African-American than among European-American men. Socioeconomic disadvantage can lead to psychosocial stress and may be linked to negative lifestyle behaviors. Regardless of socioeconomic position, African-American men routinely experience racism-induced stress. We propose a theoretical framework for an association between psychosocial stress and prostate cancer. Within the context of history and culture, we further propose that psychosocial stress may partially explain the variable incidence of prostate cancer between these diverse groups. Psychosocial stress may negatively impact the immune system leaving the individual susceptible to malignancies. Behavioral responses to psychosocial stress are amenable to change. If psychosocial stress is found to negatively impact prostate cancer risk, interventions may be designed to modify reactions to environmental demands. PMID:11572415

  17. Experimental observations and theoretical models for beam-beam phenomena

    SciTech Connect

    Kheifets, S.

    1981-03-01

    The beam-beam interaction in storage rings exhibits all the characteristics of nonintegrable dynamical systems. Here one finds all kinds of resonances, closed orbits, stable and unstable fixed points, stochastic layers, chaotic behavior, diffusion, etc. The storage ring itself being an expensive device nevertheless while constructed and put into operation presents a good opportunity of experimentally studying the long-time behavior of both conservative (proton machines) and nonconservative (electron machines) dynamical systems - the number of bunch-bunch interactions routinely reaches values of 10/sup 10/-10/sup 11/ and could be increased by decreasing the beam current. At the same time the beam-beam interaction puts practical limits for the yield of the storage ring. This phenomenon not only determines the design value of main storage ring parameters (luminosity, space charge parameters, beam current), but also in fact prevents many of the existing storage rings from achieving design parameters. Hence, the problem has great practical importance along with its enormous theoretical interest. A brief overview of the problem is presented.

  18. The development of a model for predicting passenger acceptance of short-haul air transportation systems

    NASA Technical Reports Server (NTRS)

    Kuhlthau, A. R.; Jacobson, I. D.

    1977-01-01

    Meaningful criteria and methodology for assessing, particularly in the area of ride quality, the potential acceptability to the traveling public of present and future transportation systems were investigated. Ride quality was found to be one of the important variables affecting the decision of users of air transportation, and to be influenced by several environmental factors, especially motion, noise, pressure, temperature, and seating. Models were developed to quantify the relationship of subjective comfort to all of these parameters and then were exercised for a variety of situations. Passenger satisfaction was found to be strongly related to ride quality and was so modeled. A computer program was developed to assess the comfort and satisfaction levels of passengers on aircraft subjected to arbitrary flight profiles over arbitrary terrain. A model was deduced of the manner in which passengers integrate isolated segments of a flight to obtain an overall trip comfort rating. A method was established for assessing the influence of other links (e.g., access, terminal conditions) in the overall passenger trip.

  19. Ignition temperature of magnesium powder clouds: a theoretical model.

    PubMed

    Chunmiao, Yuan; Chang, Li; Gang, Li; Peihong, Zhang

    2012-11-15

    Minimum ignition temperature of dust clouds (MIT-DC) is an important consideration when adopting explosion prevention measures. This paper presents a model for determining minimum ignition temperature for a magnesium powder cloud under conditions simulating a Godbert-Greenwald (GG) furnace. The model is based on heterogeneous oxidation of metal particles and Newton's law of motion, while correlating particle size, dust concentration, and dust dispersion pressure with MIT-DC. The model predicted values in close agreement with experimental data and is especially useful in predicting temperature and velocity change as particles pass through the furnace tube.

  20. Theoretical study of gas hydrate decomposition kinetics: model predictions.

    PubMed

    Windmeier, Christoph; Oellrich, Lothar R

    2013-11-27

    In order to provide an estimate of intrinsic gas hydrate dissolution and dissociation kinetics, the Consecutive Desorption and Melting Model (CDM) was developed in a previous publication (Windmeier, C.; Oellrich, L. R. J. Phys. Chem. A 2013, 117, 10151-10161). In this work, an extensive summary of required model data is given. Obtained model predictions are discussed with respect to their temperature dependence as well as their significance for technically relevant areas of gas hydrate decomposition. As a result, an expression for determination of the intrinsic gas hydrate decomposition kinetics for various hydrate formers is given together with an estimate for the maximum possible rates of gas hydrate decomposition. PMID:24199870

  1. Theoretical model of impact damage in structural ceramics

    NASA Technical Reports Server (NTRS)

    Liaw, B. M.; Kobayashi, A. S.; Emery, A. G.

    1984-01-01

    This paper presents a mechanistically consistent model of impact damage based on elastic failures due to tensile and shear overloading. An elastic axisymmetric finite element model is used to determine the dynamic stresses generated by a single particle impact. Local failures in a finite element are assumed to occur when the primary/secondary principal stresses or the maximum shear stress reach critical tensile or shear stresses, respectively. The succession of failed elements thus models macrocrack growth. Sliding motions of cracks, which closed during unloading, are resisted by friction and the unrecovered deformation represents the 'plastic deformation' reported in the literature. The predicted ring cracks on the contact surface, as well as the cone cracks, median cracks, radial cracks, lateral cracks, and damage-induced porous zones in the interior of hot-pressed silicon nitride plates, matched those observed experimentally. The finite element model also predicted the uplifting of the free surface surrounding the impact site.

  2. Theoretical models for duct acoustic propagation and radiation

    NASA Technical Reports Server (NTRS)

    Eversman, Walter

    1991-01-01

    The development of computational methods in acoustics has led to the introduction of analysis and design procedures which model the turbofan inlet as a coupled system, simultaneously modeling propagation and radiation in the presence of realistic internal and external flows. Such models are generally large, require substantial computer speed and capacity, and can be expected to be used in the final design stages, with the simpler models being used in the early design iterations. Emphasis is given to practical modeling methods that have been applied to the acoustical design problem in turbofan engines. The mathematical model is established and the simplest case of propagation in a duct with hard walls is solved to introduce concepts and terminologies. An extensive overview is given of methods for the calculation of attenuation in uniform ducts with uniform flow and with shear flow. Subsequent sections deal with numerical techniques which provide an integrated representation of duct propagation and near- and far-field radiation for realistic geometries and flight conditions.

  3. Design theoretic analysis of three system modeling frameworks.

    SciTech Connect

    McDonald, Michael James

    2007-05-01

    This paper analyzes three simulation architectures from the context of modeling scalability to address System of System (SoS) and Complex System problems. The paper first provides an overview of the SoS problem domain and reviews past work in analyzing model and general system complexity issues. It then identifies and explores the issues of vertical and horizontal integration as well as coupling and hierarchical decomposition as the system characteristics and metrics against which the tools are evaluated. In addition, it applies Nam Suh's Axiomatic Design theory as a construct for understanding coupling and its relationship to system feasibility. Next it describes the application of MATLAB, Swarm, and Umbra (three modeling and simulation approaches) to modeling swarms of Unmanned Flying Vehicle (UAV) agents in relation to the chosen characteristics and metrics. Finally, it draws general conclusions for analyzing model architectures that go beyond those analyzed. In particular, it identifies decomposition along phenomena of interaction and modular system composition as enabling features for modeling large heterogeneous complex systems.

  4. The acceptance model of intuitive eating: a comparison of women in emerging adulthood, early adulthood, and middle adulthood.

    PubMed

    Augustus-Horvath, Casey L; Tylka, Tracy L

    2011-01-01

    The acceptance model of intuitive eating (Avalos & Tylka, 2006) posits that body acceptance by others helps women appreciate their body and resist adopting an observer's perspective of their body, which contribute to their eating intuitively/adaptively. We extended this model by integrating body mass index (BMI) into its structure and investigating it with emerging (ages 18-25 years old, n = 318), early (ages 26-39 years old, n = 238), and middle (ages 40-65 years old, n = 245) adult women. Multiple-group analysis revealed that this model fit the data for all age groups. Body appreciation and resistance to adopt an observer's perspective mediated the body acceptance by others-intuitive eating link. Body acceptance by others mediated the social support-body appreciation and BMI-body appreciation links. Early and middle adult women had stronger negative BMI-body acceptance by others and BMI-intuitive eating relationships and a stronger positive body acceptance by others-body appreciation relationship than emerging adult women. Early adult women had a stronger positive resistance to adopt observer's perspective-body appreciation relationship than emerging and middle adult women.

  5. Theoretical and computational models of biological ion channels

    NASA Astrophysics Data System (ADS)

    Roux, Benoit

    2004-03-01

    A theoretical framework for describing ion conduction through biological molecular pores is established and explored. The framework is based on a statistical mechanical formulation of the transmembrane potential (1) and of the equilibrium multi-ion potential of mean forces through selective ion channels (2). On the basis of these developments, it is possible to define computational schemes to address questions about the non-equilibrium flow of ions through ion channels. In the case of narrow channels (gramicidin or KcsA), it is possible to characterize the ion conduction in terms of the potential of mean force of the ions along the channel axis (i.e., integrating out the off-axis motions). This has been used for gramicidin (3) and for KcsA (4,5). In the case of wide pores (i.e., OmpF porin), this is no longer a good idea, but it is possible to use a continuum solvent approximations. In this case, a grand canonical monte carlo brownian dynamics algorithm was constructed for simulating the non-equilibrium flow of ions through wide pores. The results were compared with those from the Poisson-Nernst-Planck mean-field electrodiffusion theory (6-8). References; 1. B. Roux, Biophys. J. 73:2980-2989 (1997); 2. B. Roux, Biophys. J. 77, 139-153 (1999); 3. Allen, Andersen and Roux, PNAS (2004, in press); 4. Berneche and Roux. Nature, 414:73-77 (2001); 5. Berneche and Roux. PNAS, 100:8644-8648 (2003); 6. W. Im and S. Seefeld and B. Roux, Biophys. J. 79:788-801 (2000); 7. W. Im and B. Roux, J. Chem. Phys. 115:4850-4861 (2001); 8. W. Im and B. Roux, J. Mol. Biol. 322:851-869 (2002).

  6. Ray-theoretical modeling of secondary microseism P-waves

    NASA Astrophysics Data System (ADS)

    Farra, V.; Stutzmann, E.; Gualtieri, L.; Schimmel, M.; Ardhuin, F.

    2016-06-01

    Secondary microseism sources are pressure fluctuations close to the ocean surface. They generate acoustic P-waves that propagate in water down to the ocean bottom where they are partly reflected, and partly transmitted into the crust to continue their propagation through the Earth. We present the theory for computing the displacement power spectral density of secondary microseism P-waves recorded by receivers in the far field. In the frequency domain, the P-wave displacement can be modeled as the product of (1) the pressure source, (2) the source site effect that accounts for the constructive interference of multiply reflected P-waves in the ocean, (3) the propagation from the ocean bottom to the stations, (4) the receiver site effect. Secondary microseism P-waves have weak amplitudes, but they can be investigated by beamforming analysis. We validate our approach by analyzing the seismic signals generated by Typhoon Ioke (2006) and recorded by the Southern California Seismic Network. Back projecting the beam onto the ocean surface enables to follow the source motion. The observed beam centroid is in the vicinity of the pressure source derived from the ocean wave model WAVEWATCH IIIR. The pressure source is then used for modeling the beam and a good agreement is obtained between measured and modeled beam amplitude variation over time. This modeling approach can be used to invert P-wave noise data and retrieve the source intensity and lateral extent.

  7. Information-Theoretic Modeling of Trichromacy Coding of Light Spectrum

    NASA Astrophysics Data System (ADS)

    Benoit, Landry; Belin, Étienne; Rousseau, David; Chapeau-Blondeau, François

    2014-07-01

    Trichromacy is the representation of a light spectrum by three scalar coordinates. Such representation is universally implemented by the human visual system and by RGB (Red Green Blue) cameras. We propose here an informational model for trichromacy. Based on a statistical analysis of the dynamics of individual photons, the model demonstrates a possibility for describing trichromacy as an information channel, for which the input-output mutual information can be computed to serve as a measure of performance. The capabilities and significance of the informational model are illustrated and motivated in various situations. The model especially enables an assessment of the influence of the spectral sensitivities of the three types of photodetectors realizing the trichromatic representation. It provides a criterion to optimize possibly adjustable parameters of the spectral sensitivities such as their center wavelength, spectral width or magnitude. The model shows, for instance, the usefulness of some overlap with smooth graded spectral sensitivities, as observed for instance in the human retina. The approach also, starting from hyperspectral images with high spectral resolution measured in the laboratory, can be used to devise low-cost trichromatic imaging systems optimized for observation of specific spectral signatures. This is illustrated with an example from plant science, and demonstrates a potential of application especially to life sciences. The approach particularizes connections between physics, biophysics and information theory.

  8. Ray-theoretical modeling of secondary microseism P waves

    NASA Astrophysics Data System (ADS)

    Farra, V.; Stutzmann, E.; Gualtieri, L.; Schimmel, M.; Ardhuin, F.

    2016-09-01

    Secondary microseism sources are pressure fluctuations close to the ocean surface. They generate acoustic P waves that propagate in water down to the ocean bottom where they are partly reflected and partly transmitted into the crust to continue their propagation through the Earth. We present the theory for computing the displacement power spectral density of secondary microseism P waves recorded by receivers in the far field. In the frequency domain, the P-wave displacement can be modeled as the product of (1) the pressure source, (2) the source site effect that accounts for the constructive interference of multiply reflected P waves in the ocean, (3) the propagation from the ocean bottom to the stations and (4) the receiver site effect. Secondary microseism P waves have weak amplitudes, but they can be investigated by beamforming analysis. We validate our approach by analysing the seismic signals generated by typhoon Ioke (2006) and recorded by the Southern California Seismic Network. Backprojecting the beam onto the ocean surface enables to follow the source motion. The observed beam centroid is in the vicinity of the pressure source derived from the ocean wave model WAVEWATCH IIIR. The pressure source is then used for modeling the beam and a good agreement is obtained between measured and modeled beam amplitude variation over time. This modeling approach can be used to invert P-wave noise data and retrieve the source intensity and lateral extent.

  9. PET-Specific Parameters and Radiotracers in Theoretical Tumour Modelling

    PubMed Central

    Marcu, Loredana G.; Bezak, Eva

    2015-01-01

    The innovation of computational techniques serves as an important step toward optimized, patient-specific management of cancer. In particular, in silico simulation of tumour growth and treatment response may eventually yield accurate information on disease progression, enhance the quality of cancer treatment, and explain why certain therapies are effective where others are not. In silico modelling is demonstrated to considerably benefit from information obtainable with PET and PET/CT. In particular, models have successfully integrated tumour glucose metabolism, cell proliferation, and cell oxygenation from multiple tracers in order to simulate tumour behaviour. With the development of novel radiotracers to image additional tumour phenomena, such as pH and gene expression, the value of PET and PET/CT data for use in tumour models will continue to grow. In this work, the use of PET and PET/CT information in in silico tumour models is reviewed. The various parameters that can be obtained using PET and PET/CT are detailed, as well as the radiotracers that may be used for this purpose, their utility, and limitations. The biophysical measures used to quantify PET and PET/CT data are also described. Finally, a list of in silico models that incorporate PET and/or PET/CT data is provided and reviewed. PMID:25788973

  10. Theoretical modeling of electron mobility in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Aitken, Frédéric; Bonifaci, Nelly; von Haeften, Klaus; Eloranta, Jussi

    2016-07-01

    The Orsay-Trento bosonic density functional theory model is extended to include dissipation due to the viscous response of superfluid 4He present at finite temperatures. The viscous functional is derived from the Navier-Stokes equation by using the Madelung transformation and includes the contribution of interfacial viscous response present at the gas-liquid boundaries. This contribution was obtained by calibrating the model against the experimentally determined electron mobilities from 1.2 K to 2.1 K along the saturated vapor pressure line, where the viscous response is dominated by thermal rotons. The temperature dependence of ion mobility was calculated for several different solvation cavity sizes and the data are rationalized in the context of roton scattering and Stokes limited mobility models. Results are compared to the experimentally observed "exotic ion" data, which provides estimates for the corresponding bubble sizes in the liquid. Possible sources of such ions are briefly discussed.

  11. A control theoretic model of driver steering behavior

    NASA Technical Reports Server (NTRS)

    Donges, E.

    1977-01-01

    A quantitative description of driver steering behavior such as a mathematical model is presented. The steering task is divided into two levels: (1) the guidance level involving the perception of the instantaneous and future course of the forcing function provided by the forward view of the road, and the response to it in an anticipatory open-loop control mode; (2) the stabilization level whereby any occuring deviations from the forcing function are compensated for in a closed-loop control mode. This concept of the duality of the driver's steering activity led to a newly developed two-level model of driver steering behavior. Its parameters are identified on the basis of data measured in driving simulator experiments. The parameter estimates of both levels of the model show significant dependence on the experimental situation which can be characterized by variables such as vehicle speed and desired path curvature.

  12. Theoretical modeling of electron mobility in superfluid (4)He.

    PubMed

    Aitken, Frédéric; Bonifaci, Nelly; von Haeften, Klaus; Eloranta, Jussi

    2016-07-28

    The Orsay-Trento bosonic density functional theory model is extended to include dissipation due to the viscous response of superfluid (4)He present at finite temperatures. The viscous functional is derived from the Navier-Stokes equation by using the Madelung transformation and includes the contribution of interfacial viscous response present at the gas-liquid boundaries. This contribution was obtained by calibrating the model against the experimentally determined electron mobilities from 1.2 K to 2.1 K along the saturated vapor pressure line, where the viscous response is dominated by thermal rotons. The temperature dependence of ion mobility was calculated for several different solvation cavity sizes and the data are rationalized in the context of roton scattering and Stokes limited mobility models. Results are compared to the experimentally observed "exotic ion" data, which provides estimates for the corresponding bubble sizes in the liquid. Possible sources of such ions are briefly discussed. PMID:27475346

  13. Flavor symmetry based MSSM: Theoretical models and phenomenological analysis

    NASA Astrophysics Data System (ADS)

    Babu, K. S.; Gogoladze, Ilia; Raza, Shabbar; Shafi, Qaisar

    2014-09-01

    We present a class of supersymmetric models in which symmetry considerations alone dictate the form of the soft SUSY breaking Lagrangian. We develop a class of minimal models, denoted as sMSSM—for flavor symmetry-based minimal supersymmetric standard model—that respect a grand unified symmetry such as SO(10) and a non-Abelian flavor symmetry H which suppresses SUSY-induced flavor violation. Explicit examples are constructed with the flavor symmetry being gauged SU(2)H and SO(3)H with the three families transforming as 2+1 and 3 representations, respectively. A simple solution is found in the case of SU(2)H for suppressing the flavor violating D-terms based on an exchange symmetry. Explicit models based on SO(3)H without the D-term problem are developed. In addition, models based on discrete non-Abelian flavor groups are presented which are automatically free from D-term issues. The permutation group S3 with a 2+1 family assignment, as well as the tetrahedral group A4 with a 3 assignment are studied. In all cases, a simple solution to the SUSY CP problem is found, based on spontaneous CP violation leading to a complex quark mixing matrix. We develop the phenomenology of the resulting sMSSM, which is controlled by seven soft SUSY breaking parameters for both the 2+1 assignment and the 3 assignment of fermion families. These models are special cases of the phenomenological MSSM (pMSSM), but with symmetry restrictions. We discuss the parameter space of sMSSM compatible with LHC searches, B-physics constraints and dark matter relic abundance. Fine-tuning in these models is relatively mild, since all SUSY particles can have masses below about 3 TeV.

  14. Theoretical models for ultrashort electromagnetic pulse propagation in nonlinear metamaterials

    SciTech Connect

    Wen, Shuangchun; Xiang, Yuanjiang; Dai, Xiaoyu; Tang, Zhixiang; Su, Wenhua; Fan, Dianyuan

    2007-03-15

    A metamaterial (MM) differs from an ordinary optical material mainly in that it has a dispersive magnetic permeability and offers greatly enhanced design freedom to alter the linear and nonlinear properties. This makes it possible for us to control the propagation of ultrashort electromagnetic pulses at will. Here we report on generic features of ultrashort electromagnetic pulse propagation and demonstrate the controllability of both the linear and nonlinear parameters of models for pulse propagation in MMs. First, we derive a generalized system of coupled three-dimensional nonlinear Schroedinger equations (NLSEs) suitable for few-cycle pulse propagation in a MM with both nonlinear electric polarization and nonlinear magnetization. The coupled equations recover previous models for pulse propagation in both ordinary material and a MM under the same conditions. Second, by using the coupled NLSEs in the Drude dispersive model as an example, we identify the respective roles of the dispersive electric permittivity and magnetic permeability in ultrashort pulse propagation and disclose some additional features of pulse propagation in MMs. It is shown that, for linear propagation, the sign and magnitude of space-time focusing can be controlled through adjusting the linear dispersive permittivity and permeability. For nonlinear propagation, the linear dispersive permittivity and permeability are incorporated into the nonlinear magnetization and nonlinear polarization, respectively, resulting in controllable magnetic and electric self-steepening effects and higher-order dispersively nonlinear terms in the propagation models.

  15. Photoabsorption spectrum of helium trimer cation—Theoretical modeling

    SciTech Connect

    Kalus, René; Karlický, František; Lepetit, Bruno; Paidarová, Ivana; Gadea, Florent Xavier

    2013-11-28

    The photoabsorption spectrum of He{sub 3}{sup +} is calculated for two semiempirical models of intracluster interactions and compared with available experimental data reported in the middle UV range [H. Haberland and B. von Issendorff, J. Chem. Phys. 102, 8773 (1995)]. Nuclear delocalization effects are investigated via several approaches comprising quantum samplings using either exact or approximate (harmonic) nuclear wavefunctions, as well as classical samplings based on the Monte Carlo methodology. Good agreement with the experiment is achieved for the model by Knowles et al., [Mol. Phys. 85, 243 (1995); Mol. Phys. 87, 827 (1996)] whereas the model by Calvo et al., [J. Chem. Phys. 135, 124308 (2011)] exhibits non-negligible deviations from the experiment. Predictions of far UV absorption spectrum of He{sub 3}{sup +}, for which no experimental data are presently available, are reported for both models and compared to each other as well as to the photoabsorption spectrum of He{sub 2}{sup +}. A simple semiempirical point-charge approximation for calculating transition probabilities is shown to perform well for He{sub 3}{sup +}.

  16. SBS mitigation with 'two-tone' amplification: a theoretical model

    NASA Astrophysics Data System (ADS)

    Bronder, T. J.; Shay, T. M.; Dajani, I.; Gavrielides, A.; Robin, C. A.; Lu, C. A.

    2008-02-01

    A new technique for mitigating stimulated Brillouin scattering (SBS) effects in narrow-linewidth Yb-doped fiber amplifiers is demonstrated with a model that reduces to solving an 8×8 system of coupled nonlinear equations with the gain, SBS, and four-wave mixing (FMW) incorporated into the model. This technique uses two seed signals, or 'two-tones', with each tone reaching its SBS threshold almost independently and thus increasing the overall threshold for SBS in the fiber amplifier. The wavelength separation of these signals is also selected to avoid FWM, which in this case possesses the next lowest nonlinear effects threshold. This model predicts an output power increase of 86% (at SBS threshold with no signs of FWM) for a 'two-tone' amplifier with seed signals at 1064nm and 1068nm, compared to a conventional fiber amplifier with a single 1064nm seed. The model is also used to simulate an SBS-suppressing fiber amplifier to test the regime where FWM is the limiting factor. In this case, an optimum wavelength separation of 3nm to 10nm prevents FWM from reaching threshold. The optimum ratio of the input power for the two seed signals in 'two-tone' amplification is also tested. Future experimental verification of this 'two-tone' technique is discussed.

  17. Voronoi Cell Patterns: theoretical model and application to submonolayer growth

    NASA Astrophysics Data System (ADS)

    González, Diego Luis; Einstein, T. L.

    2012-02-01

    We use a simple fragmentation model to describe the statistical behavior of the Voronoi cell patterns generated by a homogeneous and isotropic set of points in 1D and in 2D. In particular, we are interested in the distribution of sizes of these Voronoi cells. Our model is completely defined by two probability distributions in 1D and again in 2D, the probability to add a new point inside an existing cell and the probability that this new point is at a particular position relative to the preexisting point inside this cell. In 1D the first distribution depends on a single parameter while the second distribution is defined through a fragmentation kernel; in 2D both distributions depend on a single parameter. The fragmentation kernel and the control parameters are closely related to the physical properties of the specific system under study. We apply our model to describe the Voronoi cell patterns of island nucleation for critical island sizes i=0,1,2,3. Experimental results for the Voronoi cells of InAs/GaAs quantum dots are also described by our model.

  18. [Theoretical model for rocky desertification control in karst area].

    PubMed

    Liang, Liang; Liu, Zhi-Xiao; Zhang, Dai-Gui; Deng, Kai-Dong; Zhang, You-Xiang

    2007-03-01

    Based on the basic principles of restoration ecology, the trigger-action model for rocky desertification control was proposed, i. e. , the ability that an ecosystem enables itself to develop was called dominant force, and the interfering factor resulting in the deviation of the climax of ecological succession from its preconcerted status was called trigger factor. The ultimate status of ecological succession was determined by the interaction of dominant force and trigger factor. Rocky desertification was the result of serious malignant triggers, and its control was the process of benign triggers in using the ecological restoration method of artificial designs to activate the natural designing ability of an ecosystem. The ecosystem of Karst rocky desertification in Fenghuang County with restoration measures was taken as a case to test the model, and the results showed that the restoration measures based on trigger-action model markedly improved the physical and chemical properties of soil and increased the diversity of plant. There was a benign trigger between the restoration measures and the Karst area. The rationality of the trigger-action model was primarily tested by the results in practice. PMID:17552199

  19. Testing Theoretical Models of Magnetic Damping Using an Air Track

    ERIC Educational Resources Information Center

    Vidaurre, Ana; Riera, Jaime; Monsoriu, Juan A.; Gimenez, Marcos H.

    2008-01-01

    Magnetic braking is a long-established application of Lenz's law. A rigorous analysis of the laws governing this problem involves solving Maxwell's equations in a time-dependent situation. Approximate models have been developed to describe different experimental results related to this phenomenon. In this paper we present a new method for the…

  20. Control theoretic model of automobile demand and gasoline consumption

    SciTech Connect

    Panerali, R.B.

    1982-01-01

    The purpose of this research is to examine the controllability of gasoline consumption and automobile demand using gasoline price as a policy instrument. The author examines the problem of replacing the standby motor-fuel rationing plan with use of the federal excise tax on gasoline. It is demonstrated that the standby targets are attainable with the tax. The problem of multiple control of automobile demand and gasoline consumption is also addressed. When the federal gasoline excise tax is used to control gasoline consumption, the policy maker can also use the tax to direct automobile demand. There exists a trade-off between various automobile demand targets and the target implied for gasoline consumption. We seek to measure this trade-off and use the results for planning. This research employs a time series of cross section data base with a disaggregated model of automobile demand, and an aggregate model of gasoline consumption. Automobile demand is divided into five mutually exclusive classes of cars. Gasoline demand is model as the sum of regular, premium, and unleaded gasoline. The pooled data base is comprised of a quarterly time series running from 1963 quarter one through 1979 quarter four, for each of the 48 continuous states. The demand equations are modelled using dynamic theories of demand. Estimates of the respective equations are made with error components and covariance techniques. Optimal control is applied to examine the gasoline-control problem.

  1. A Theoretical Model of Sexual Assault: An Empirical Test.

    ERIC Educational Resources Information Center

    White, Jacquelyn W.; Humphrey, John A.

    Koss and Dinero's (1987) comprehensive developmental model of sexual aggression asserts that sexual assault is in part a result of early sexual experiences and family violence; that sexually aggressive behaviors may be predicted by such "releaser" variables as current sexual behavior, alcohol use, and peer group support; and that use of aggression…

  2. Interpreting Unfamiliar Graphs: A Generative, Activity Theoretic Model

    ERIC Educational Resources Information Center

    Roth, Wolff-Michael; Lee, Yew Jin

    2004-01-01

    Research on graphing presents its results as if knowing and understanding were something stored in peoples' minds independent of the situation that they find themselves in. Thus, there are no models that situate interview responses to graphing tasks. How, then, we question, are the interview texts produced? How do respondents begin and end…

  3. Theoretical model for morphogenesis and cell sorting in Dictyostelium discoideum

    NASA Astrophysics Data System (ADS)

    Umeda, T.; Inouye, K.

    1999-02-01

    The morphogenetic movement and cell sorting in cell aggregates from the mound stage to the migrating slug stage of the cellular slime mold Dictyostelium discoideum were studied using a mathematical model. The model postulates that the motive force generated by the cells is in equilibrium with the internal pressure and mechanical resistance. The moving boundary problem derived from the force balance equation and the continuity equation has stationary solutions in which the aggregate takes the shape of a spheroid (or an ellipse in two-dimensional space) with the pacemaker at one of its foci, moving at a constant speed. Numerical calculations in two-dimensional space showed that an irregularly shaped aggregate changes its shape to become an ellipse as it moves. Cell aggregates consisting of two cell types differing in motive force exhibit cell sorting and become elongated, suggesting the importance of prestalk/prespore differentiation in the morphogenesis of Dictyostelium.

  4. Modeling energetic and theoretical costs of thermoregulatory strategy.

    PubMed

    Alford, John G; Lutterschmidt, William I

    2012-01-01

    Poikilothermic ectotherms have evolved behaviours that help them maintain or regulate their body temperature (T (b)) around a preferred or 'set point' temperature (T (set)). Thermoregulatory behaviors may range from body positioning to optimize heat gain to shuttling among preferred microhabitats to find appropriate environmental temperatures. We have modelled movement patterns between an active and non-active shuttling behaviour within a habitat (as a biased random walk) to investigate the potential cost of two thermoregulatory strategies. Generally, small-bodied ectotherms actively thermoregulate while large-bodied ectotherms may passively thermoconform to their environment. We were interested in the potential energetic cost for a large-bodied ectotherm if it were forced to actively thermoregulate rather than thermoconform. We therefore modelled movements and the resulting and comparative energetic costs in precisely maintaining a T (set) for a small-bodied versus large-bodied ectotherm to study and evaluate the thermoregulatory strategy.

  5. A Quantitative Examination of User Experience as an Antecedent to Student Perception in Technology Acceptance Modeling

    ERIC Educational Resources Information Center

    Butler, Rory

    2013-01-01

    Internet-enabled mobile devices have increased the accessibility of learning content for students. Given the ubiquitous nature of mobile computing technology, a thorough understanding of the acceptance factors that impact a learner's intention to use mobile technology as an augment to their studies is warranted. Student acceptance of mobile…

  6. Determinants of Intention to Use eLearning Based on the Technology Acceptance Model

    ERIC Educational Resources Information Center

    Punnoose, Alfie Chacko

    2012-01-01

    The purpose of this study was to find some of the predominant factors that determine the intention of students to use eLearning in the future. Since eLearning is not just a technology acceptance decision but also involves cognition, this study extended its search beyond the normal technology acceptance variables into variables that could affect…

  7. BL Herculis stars - Theoretical models for field variables

    NASA Technical Reports Server (NTRS)

    Carson, R.; Stothers, R.

    1982-01-01

    Type II Cepheids with periods between 1 and 3 days, commonly designated as Bl Herculis stars, have been modeled here with the aim of interpreting the wide variety of light curves observed among the field variables. Previously modeled globular cluster members are used as standard calibration objects. The major finding is that only a small range of luminosities is capable of generating a large variety of light curve types at a given period. For a mass of approximately 0.60 solar mass, the models are able to reproduce the observed mean luminosities, dispersion of mean luminosities, periods, light amplitudes, light asymmetries, and phases of secondary features in the light curves of known BL Her stars. It is possible that the metal-rich variables (which are found only in the field) have luminosities lower than those of most metal-poor variables. The present revised mass for BL Her, a metal-rich object, is not significantly different from the mean mass of the metal-poor variables.

  8. A dynamic game-theoretic model of parental care.

    PubMed

    Mcnamara, J M; Székely, T; Webb, J N; Houston, A I

    2000-08-21

    We present a model in which members of a mated pair decide whether to care for their offspring or desert them. There is a breeding season of finite length during which it is possible to produce and raise several batches of offspring. On deserting its offspring, an individual can search for a new mate. The probability of finding a mate depends on the number of individuals of each sex that are searching, which in turn depends upon the previous care and desertion decisions of all population members. We find the evolutionarily stable pattern of care over the breeding season. The feedback between behaviour and mating opportunity can result in a pattern of stable oscillations between different forms of care over the breeding season. Oscillations can also arise because the best thing for an individual to do at a particular time in the season depends on future behaviour of all population members. In the baseline model, a pair splits up after a breeding attempt, even if they both care for the offspring. In a version of the model in which a pair stays together if they both care, the feedback between behaviour and mating opportunity can lead to more than one evolutionarily stable form of care.

  9. Mathematical, Theoretical and Phenomenological Challenges Beyond the Standard Model

    NASA Astrophysics Data System (ADS)

    Djordjević, G.; Nešić, L.; Wess, Julius

    2005-03-01

    Integrable structures in the gauge/string corespondence -- Fluxes in M-theory on 7-manifolds: Gz-, SW(3)- and SU( 2)-structures -- Noncommutative quantum field theory: review and its latest achievements -- Shadows of quantum black holes -- Yukawa quasi-unification and inflation -- Supersymmetric grand unification: the quest for the theory -- Spin foam models of quantum gravity -- Riemann-cartan space-time in stringy geometry -- Can black hole relax unitarily? -- Deformed coordinate spaces derivatives.Deformed coherent state solution to multiparticle stochastic processes -- Non-commutative GUTS, standard model and C, P, T properties from seiberg-witten map -- Seesaw, susy and SO(10) -- On the dynamics of BMN operators of finite size and the , model of string bits -- Divergencies in &expanded noncommutative SU( 2) yang-mills theory -- Heterotic string compactifications with fluxes -- Symmetries and supersymmetries of the dirac-type operators on euclidean taub-NUT space -- Real and p-Adic aspects of quantization of tachyons -- Skew-symmetric lax polynomial matrices and integrable rigid body systems -- Supersymmetric quantum field theories -- Parastatistics algebras and combinatorics -- Noncommutative D-branes on group manifolds -- High-energy bounds on the scattering amplitude in noncommutative quantum field theory -- Many faces of D-branes: from flat space, via AdS to pp-waves.

  10. A dynamic game-theoretic model of parental care.

    PubMed

    Mcnamara, J M; Székely, T; Webb, J N; Houston, A I

    2000-08-21

    We present a model in which members of a mated pair decide whether to care for their offspring or desert them. There is a breeding season of finite length during which it is possible to produce and raise several batches of offspring. On deserting its offspring, an individual can search for a new mate. The probability of finding a mate depends on the number of individuals of each sex that are searching, which in turn depends upon the previous care and desertion decisions of all population members. We find the evolutionarily stable pattern of care over the breeding season. The feedback between behaviour and mating opportunity can result in a pattern of stable oscillations between different forms of care over the breeding season. Oscillations can also arise because the best thing for an individual to do at a particular time in the season depends on future behaviour of all population members. In the baseline model, a pair splits up after a breeding attempt, even if they both care for the offspring. In a version of the model in which a pair stays together if they both care, the feedback between behaviour and mating opportunity can lead to more than one evolutionarily stable form of care. PMID:10931755

  11. Modeling postpartum depression in rats: theoretic and methodological issues

    PubMed Central

    Ming, LI; Shinn-Yi, CHOU

    2016-01-01

    The postpartum period is when a host of changes occur at molecular, cellular, physiological and behavioral levels to prepare female humans for the challenge of maternity. Alteration or prevention of these normal adaptions is thought to contribute to disruptions of emotion regulation, motivation and cognitive abilities that underlie postpartum mental disorders, such as postpartum depression. Despite the high incidence of this disorder, and the detrimental consequences for both mother and child, its etiology and related neurobiological mechanisms remain poorly understood, partially due to the lack of appropriate animal models. In recent decades, there have been a number of attempts to model postpartum depression disorder in rats. In the present review, we first describe clinical symptoms of postpartum depression and discuss known risk factors, including both genetic and environmental factors. Thereafter, we discuss various rat models that have been developed to capture various aspects of this disorder and knowledge gained from such attempts. In doing so, we focus on the theories behind each attempt and the methods used to achieve their goals. Finally, we point out several understudied areas in this field and make suggestions for future directions. PMID:27469254

  12. Modeling postpartum depression in rats: theoretic and methodological issues.

    PubMed

    Li, Ming; Chou, Shinn-Yi

    2016-07-18

    The postpartum period is when a host of changes occur at molecular, cellular, physiological and behavioral levels to prepare female humans for the challenge of maternity. Alteration or prevention of these normal adaptions is thought to contribute to disruptions of emotion regulation, motivation and cognitive abilities that underlie postpartum mental disorders, such as postpartum depression. Despite the high incidence of this disorder, and the detrimental consequences for both mother and child, its etiology and related neurobiological mechanisms remain poorly understood, partially due to the lack of appropriate animal models. In recent decades, there have been a number of attempts to model postpartum depression disorder in rats. In the present review, we first describe clinical symptoms of postpartum depression and discuss known risk factors, including both genetic and environmental factors. Thereafter, we discuss various rat models that have been developed to capture various aspects of this disorder and knowledge gained from such attempts. In doing so, we focus on the theories behind each attempt and the methods used to achieve their goals. Finally, we point out several understudied areas in this field and make suggestions for future directions. PMID:27469254

  13. A Theoretical Model for the Associative Nature of Conference Participation

    PubMed Central

    Smiljanić, Jelena; Chatterjee, Arnab; Kauppinen, Tomi; Mitrović Dankulov, Marija

    2016-01-01

    Participation in conferences is an important part of every scientific career. Conferences provide an opportunity for a fast dissemination of latest results, discussion and exchange of ideas, and broadening of scientists’ collaboration network. The decision to participate in a conference depends on several factors like the location, cost, popularity of keynote speakers, and the scientist’s association with the community. Here we discuss and formulate the problem of discovering how a scientist’s previous participation affects her/his future participations in the same conference series. We develop a stochastic model to examine scientists’ participation patterns in conferences and compare our model with data from six conferences across various scientific fields and communities. Our model shows that the probability for a scientist to participate in a given conference series strongly depends on the balance between the number of participations and non-participations during his/her early connections with the community. An active participation in a conference series strengthens the scientist’s association with that particular conference community and thus increases the probability of future participations. PMID:26859404

  14. Learning with Interactive Whiteboards: Determining the Factors on Promoting Interactive Whiteboards to Students by Technology Acceptance Model

    ERIC Educational Resources Information Center

    Kilic, Eylem; Güler, Çetin; Çelik, H. Eray; Tatli, Cemal

    2015-01-01

    Purpose: The purpose of this study is to investigate the factors which might affect the intention to use interactive whiteboards (IWBs) by university students, using Technology Acceptance Model by the structural equation modeling approach. The following hypothesis guided the current study: H1. There is a positive relationship between IWB…

  15. Theoretical models for the emergence of biomolecular homochirality

    NASA Astrophysics Data System (ADS)

    Walker, Sara Imari

    Little is known about the emergence of life from nonliving precursors. A key missing-piece is the origin of homochirality: nearly all life is characterized by exclusively dextrorotary sugars and levorotary amino acids. The research presented in this thesis addresses the challenge of uncovering mechanisms for chiral symmetry breaking in a prebiotic environment and implications for the origin of life on Earth. Expanding on a well-known model for chiral selection through polymerization, and modeling the spatiotemporal dynamics starting from near-racemic initial conditions, it is demonstrated that the net chirality of molecular building blocks grows with the longest polymer in the reaction network (of length N) with critical behavior for the onset of chiral asymmetry determined by the value of N. This surprising result indicates that significant chiral asymmetry occurs only for systems which permit growth of long polymers. Expanding on this work, the effects of environmental disturbances on the evolution of chirality in prebiotic reaction-diffusion networks are studied via the implementation of a stochastic spatiotemporal Langevin equation. The results show that environmental interactions can have significant impact on the evolution of prebiotic chirality: the history of prebiotic chirality is therefore interwoven with the Earths early environmental history in a mechanism we call punctuated chirality. This result establishes that the onset of homochirality is not an isolated phenomenon: chiral selection must occur in tandem with the transition from chemistry to biology, otherwise the prebiotic soup is unstable to environmental events. Addressing the challenge of understanding the role of chirality in the transition from non-life to life, the diffusive slowdown of reaction networks induced, for example, through tidal cycles or evaporating pools, is modeled. The results of this study demonstrate that such diffusive slowdown leads to the stabilization of homochiral

  16. GSTARS computer models and their applications, part I: theoretical development

    USGS Publications Warehouse

    Yang, C.T.; Simoes, F.J.M.

    2008-01-01

    GSTARS is a series of computer models developed by the U.S. Bureau of Reclamation for alluvial river and reservoir sedimentation studies while the authors were employed by that agency. The first version of GSTARS was released in 1986 using Fortran IV for mainframe computers. GSTARS 2.0 was released in 1998 for personal computer application with most of the code in the original GSTARS revised, improved, and expanded using Fortran IV/77. GSTARS 2.1 is an improved and revised GSTARS 2.0 with graphical user interface. The unique features of all GSTARS models are the conjunctive use of the stream tube concept and of the minimum stream power theory. The application of minimum stream power theory allows the determination of optimum channel geometry with variable channel width and cross-sectional shape. The use of the stream tube concept enables the simulation of river hydraulics using one-dimensional numerical solutions to obtain a semi-two- dimensional presentation of the hydraulic conditions along and across an alluvial channel. According to the stream tube concept, no water or sediment particles can cross the walls of stream tubes, which is valid for many natural rivers. At and near sharp bends, however, sediment particles may cross the boundaries of stream tubes. GSTARS3, based on FORTRAN 90/95, addresses this phenomenon and further expands the capabilities of GSTARS 2.1 for cohesive and non-cohesive sediment transport in rivers and reservoirs. This paper presents the concepts, methods, and techniques used to develop the GSTARS series of computer models, especially GSTARS3. ?? 2008 International Research and Training Centre on Erosion and Sedimentation and the World Association for Sedimentation and Erosion Research.

  17. [The Technology Acceptance Model and Its Application in a Telehealth Program for the Elderly With Chronic Illnesses].

    PubMed

    Chang, Chi-Ping

    2015-06-01

    Many technology developments hold the potential to improve the quality of life of people and make life easier and more comfortable. New technologies have been well accepted by most people. Information sharing in particular is a major catalyst of change in our current technology-based society. Technology has widely innovated life and drastically changed lifestyles. The Technology Acceptance Model (TAM), a model developed to address the rapid advances in computer technology, is used to explain and predict user acceptance of new information technology. In the past, businesses have used the TAM as an assessment tool to predict user acceptance when introducing new technology products. They have also used external factors in the model to influence user perceptions and beliefs and to ensure the successful spread of new technologies. Informatization plays a critical role in healthcare services. Due to the rapid aging of populations and upward trends in the incidence of chronic illness, requirements for long-term care have increased in both quality and quantity. Therefore, there has been an increased emphasis on integrating healthcare and information technology. However, most elderly are significantly less adept at technology use than the general population. Therefore, we reexamined the effect that the essential concepts in a TAM exerted on technology acceptance. In the present study, the technology acceptance experience with regard to telehealth of the elderly was used as an example to explain how the revised technology acceptance model (TAM 2) may be effectively applied to enhance the understanding of technology care among nurses. The results may serve as a reference for future research on healthcare-technology use in long-term care or in elderly populations.

  18. Theoretical model of a piezoelectric composite spinal fusion interbody implant.

    PubMed

    Tobaben, Nicholas E; Domann, John P; Arnold, Paul M; Friis, Elizabeth A

    2014-04-01

    Failure rates of spinal fusion are high in smokers and diabetics. The authors are investigating the development of a piezoelectric composite biomaterial and interbody device design that could generate clinically relevant levels of electrical stimulation to help improve the rate of fusion for these patients. A lumped parameter model of the piezoelectric composite implant was developed based on a model that has been utilized to successfully predict power generation for piezoceramics. Seven variables (fiber material, matrix material, fiber volume fraction, fiber aspect ratio, implant cross-sectional area, implant thickness, and electrical load resistance) were parametrically analyzed to determine their effects on power generation within reasonable implant constraints. Influences of implant geometry and fiber aspect ratio were independent of material parameters. For a cyclic force of constant magnitude, implant thickness was directly and cross-sectional area inversely proportional to power generation potential. Fiber aspect ratios above 30 yielded maximum power generation potential while volume fractions above 15% showed superior performance. This investigation demonstrates the feasibility of using composite piezoelectric biomaterials in medical implants to generate therapeutic levels of direct current electrical stimulation. The piezoelectric spinal fusion interbody implant shows promise for helping increase success rates of spinal fusion.

  19. Theoretical Modeling of Various Spectroscopies for Cuprates and Topological Insulators

    NASA Astrophysics Data System (ADS)

    Basak, Susmita

    Spectroscopies resolved highly in momentum, energy and/or spatial dimensions are playing an important role in unraveling key properties of wide classes of novel materials. However, spectroscopies do not usually provide a direct map of the underlying electronic spectrum, but act as a complex 'filter' to produce a 'mapping' of the underlying energy levels, Fermi surfaces (FSs) and excitation spectra. The connection between the electronic spectrum and the measured spectra is described as a generalized 'matrix element effect'. The nature of the matrix element involved differs greatly between different spectroscopies. For example, in angle-resolved photoemission (ARPES) an incoming photon knocks out an electron from the sample and the energy and momentum of the photoemitted electron is measured. This is quite different from what happens in K-edge resonant inelastic X-ray scattering (RIXS), where an X-ray photon is scattered after inducing electronic transitions near the Fermi energy through an indirect second order process, or in Compton scattering where the incident X-ray photon is scattered inelastically from an electron transferring energy and momentum to the scattering electron. For any given spectroscopy, the matrix element is, in general, a complex function of the phase space of the experiment, e.g. energy/polarization of the incoming photon and the energy/momentum/spin of the photoemitted electron in the case of ARPES. The matrix element can enhance or suppress signals from specific states, or merge signals of groups of states, making a good understanding of the matrix element effects important for not only a robust interpretation of the spectra, but also for ascertaining optimal regions of the experimental phase space for zooming in on states of the greatest interest. In this thesis I discuss a comprehensive scheme for modeling various highly resolved spectroscopies of the cuprates and topological insulators (TIs) where effects of matrix element, crystal

  20. Polarimetric signatures of sea ice. 1: Theoretical model

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.

    1995-01-01

    Physical, structral, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarmetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies to interpretation of sea ice polarimetric signatures.

  1. Polarimetric Signatures of Sea Ice. Part 1; Theoretical Model

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Drinkwater, M. R.

    1995-01-01

    Physical, structural, and electromagnetic properties and interrelating processes in sea ice are used to develop a composite model for polarimetric backscattering signatures of sea ice. Physical properties of sea ice constituents such as ice, brine, air, and salt are presented in terms of their effects on electromagnetic wave interactions. Sea ice structure and geometry of scatterers are related to wave propagation, attenuation, and scattering. Temperature and salinity, which are determining factors for the thermodynamic phase distribution in sea ice, are consistently used to derive both effective permittivities and polarimetric scattering coefficients. Polarimetric signatures of sea ice depend on crystal sizes and brine volumes, which are affected by ice growth rates. Desalination by brine expulsion, drainage, or other mechanisms modifies wave penetration and scattering. Sea ice signatures are further complicated by surface conditions such as rough interfaces, hummocks, snow cover, brine skim, or slush layer. Based on the same set of geophysical parameters characterizing sea ice, a composite model is developed to calculate effective permittivities and backscattering covariance matrices at microwave frequencies for interpretation of sea ice polarimetric signatures.

  2. PUBLISHER'S NOTE: Microfabrication by localized electrochemical deposition: experimental investigation and theoretical modelling

    NASA Astrophysics Data System (ADS)

    Said, R. A.

    2004-07-01

    During 2003, Dr R A Said published essentially duplicate versions of a paper in two archival journals: Nanotechnology and the Journal of The Electrochemical Society. The papers in question were: `Microfabrication by localized electrochemical deposition: experimental investigation and theoretical modelling' (2003 Nanotechnology 14 523) and `Shape formation of microstructures fabricated by localized electrochemical deposition' (2003 J. Electrochem. Soc. 150 C549). The two papers were submitted, revised, and published at essentially the same time. The papers used the same figures and neither paper referenced the other. Nanotechnology requires a signed copyright-transfer form assigning copyright in articles published to Institute of Physics Publishing, and the Journal of The Electrochemical Society requires the same for The Electrochemical Society. It is a tradition of long standing, stated in the information for contributors, that submission implies that the work has not been submitted, copyrighted, or accepted for publication elsewhere. Hence, duplicate publication not only raises legal questions and represents a serious breach of scientific ethics, but also leads to an unnecessary imposition on readers', referees', and editors' time. We regard this infraction as a serious matter. An apology from the author for this grave error is printed below. Author's apology I have mistakenly published similar results in two manuscripts in Nanotechnology and in the Journal of The Electrochemical Society, as stated above. I am responsible for this error. I agree with the Editors that such a practice should not have occurred, and I would like to sincerely apologize to Nanotechnology and the Journal of The Electrochemical Society, their publishers, and their readers for this matter. I will take actions in the future to prevent the occurrence of similar incidents. R A Said

  3. Theoretical model for assessing properties of local structures in metalloprotein

    NASA Astrophysics Data System (ADS)

    Koyimatu, M.; Shimahara, H.; Iwayama, M.; Sugimori, K.; Kawaguchi, K.; Saito, H.; Nagao, H.

    2013-02-01

    For model structures containing two aromatic rings such as the indole of Trp5 and the imidazole of His64 in human carbonic anhydrase (hCAII), the location and orientation of the rings with regard to each other contribute to the magnitude of the entire interaction energy. Here the energetic contribution of the indole ring of Trp5 on the imidazole ring of the "out" conformation of His64 were calculated to compare with that of the alternative "in" conformation of His64 by using the MP2/6-311++G(d,p)//B3LYP/6-31G(d,p) method. We suggest that 1) Trp5 and the "out" conformation of His64 are predicted to form a stack of planar parallel rings via π-stacking interaction and 2) the energy is 1.73-1.83 kcal/mol to stabilize the "out" conformation, compared with the "in" conformation.

  4. [A theoretical model of the transition phase in human locomotion].

    PubMed

    Beuter, A; Lefebvre, R

    1988-12-01

    In this study we examine the bifurcation of the transition between walking and running. Beuter and Lalonde (1986) have conjectured that the pertinent parameters separating walking and running can be described by a cusp singularity (Thom, 1972). In this model, the unidimensional state space is characterized by support duration and the bidimensional parameter space is characterized by the subject's weight and speed. To test this model eight males walked and ran on a motor driven treadmill at an increasing or decreasing speed with or without additional loads corresponding to 0%, 7% and 14% of their body weight. Velocities corresponding to transitions between the two modes of locomotion indicate that on the average the walk-run transition occurs at higher speed than the run-walk transition illustrating an hysteresis effect. In addition, the average difference between the transitions decreases as the load increases [mean 0 = 0.235 m/s, +/- 0.09 m/s, mean 7 = 0.104 m/s, +/- 0.07 m/s and mean 14 = 0.041 m/s, +/- 0.06 m/s] corresponding to an F ratio of F = 2.72, 0.05 less than p less than 0.1. A comparison of the differences in transition velocity at 0% and 14% is statistically different (t = 2.8, p less than 0.025). These results tend to support the existence of an elementary cusp singularity separating the two locomotion modes and suggest that the mechanisms controlling these transitions can be described by a hysterisis cycle and a small number of parameters. PMID:3219673

  5. Physician Acceptance of a Physician-Pharmacist Collaborative Treatment Model for Hypertension Management in Primary Care.

    PubMed

    Smith, Steven M; Hasan, Michaela; Huebschmann, Amy G; Penaloza, Richard; Schorr-Ratzlaff, Wagner; Sieja, Amber; Roscoe, Nicholai; Trinkley, Katy E

    2015-09-01

    Physician-pharmacist collaborative care (PPCC) is effective in improving blood pressure (BP) control, but primary care provider (PCP) engagement in such models has not been well-studied. The authors analyzed data from PPCC referrals to 108 PCPs, for patients with uncontrolled hypertension, assessing the proportion of referral requests approved, disapproved, and not responded to, and reasons for disapproval. Of 2232 persons with uncontrolled hypertension, PPCC referral requests were sent for 1516 (67.9%): 950 (62.7%) were approved, 406 (26.8%) were disapproved, and 160 (10.6%) received no response. Approval rates differed widely by PCP with a median approval rate of 75% (interquartile range, 41%-100%). The most common reasons for disapproval were: PCP prefers to manage hypertension (19%), and BP controlled per PCP (18%); 8% of cases were considered too complex for PPCC. Provider acceptance of a PPCC hypertension clinic was generally high and sustained but varied widely among PCPs. No single reason for disapproval predominated.

  6. A Theoretical Light-Curve Model for the 1999 Outburst of U Scorpii

    NASA Astrophysics Data System (ADS)

    Hachisu, Izumi; Kato, Mariko; Kato, Taichi; Matsumoto, Katsura

    2000-01-01

    A theoretical light curve for the 1999 outburst of U Scorpii is presented in order to obtain various physical parameters of the recurrent nova. Our U Sco model consists of a very massive white dwarf (WD) with an accretion disk and a lobe-filling, slightly evolved, main-sequence star (MS). The model includes a reflection effect by the companion and the accretion disk together with a shadowing effect on the companion by the accretion disk. The early visual light curve (with a linear phase of t~1-15 days after maximum) is well reproduced by a thermonuclear runaway model on a very massive WD close to the Chandrasekhar limit (MWD=1.37+/-0.01 Msolar), in which optically thick winds blowing from the WD play a key role in determining the nova duration. The ensuing plateau phase (t~15-30 days) is also reproduced by the combination of a slightly irradiated MS and a fully irradiated flaring-up disk with a radius ~1.4 times the Roche lobe size. The cooling phase (t~30-40 days) is consistent with a low-hydrogen content of X~0.05 of the envelope for the 1.37 Msolar WD. The best-fit parameters are the WD mass of MWD~1.37 Msolar, the companion mass of MMS~1.5 Msolar (0.8-2.0 Msolar is acceptable), the inclination angle of the orbit (i~80deg), and the flaring-up edge, the vertical height of which is ~0.30 times the accretion disk radius. The duration of the strong wind phase (t~0-17 days) is very consistent with the BeppoSAX supersoft X-ray detection at t~19-20 days because supersoft X-rays are self-absorbed by the massive wind. The envelope mass at the peak is estimated to be ~3×10-6 Msolar, which is indicates an average mass accretion rate of ~2.5×10-7 Msolar yr-1 during the quiescent phase between 1987 and 1999. These quantities are exactly the same as those predicted in a new progenitor model of Type Ia supernovae.

  7. TURBULENT CONVECTION MODEL IN THE OVERSHOOTING REGION. II. THEORETICAL ANALYSIS

    SciTech Connect

    Zhang, Q. S.; Li, Y. E-mail: ly@ynao.ac.cn

    2012-05-01

    Turbulent convection models (TCMs) are thought to be good tools to deal with the convective overshooting in the stellar interior. However, they are too complex to be applied to calculations of stellar structure and evolution. In order to understand the physical processes of the convective overshooting and to simplify the application of TCMs, a semi-analytic solution is necessary. We obtain the approximate solution and asymptotic solution of the TCM in the overshooting region, and find some important properties of the convective overshooting. (1) The overshooting region can be partitioned into three parts: a thin region just outside the convective boundary with high efficiency of turbulent heat transfer, a power-law dissipation region of turbulent kinetic energy in the middle, and a thermal dissipation area with rapidly decreasing turbulent kinetic energy. The decaying indices of the turbulent correlations k, u{sub r}'T'-bar, and T'T'-bar are only determined by the parameters of the TCM, and there is an equilibrium value of the anisotropic degree {omega}. (2) The overshooting length of the turbulent heat flux u{sub r}'T'-bar is about 1H{sub k} (H{sub k} = |dr/dln k|). (3) The value of the turbulent kinetic energy at the convective boundary k{sub C} can be estimated by a method called the maximum of diffusion. Turbulent correlations in the overshooting region can be estimated by using k{sub C} and exponentially decreasing functions with the decaying indices.

  8. Theoretical Modeling of (99)Tc NMR Chemical Shifts.

    PubMed

    Hall, Gabriel B; Andersen, Amity; Washton, Nancy M; Chatterjee, Sayandev; Levitskaia, Tatiana G

    2016-09-01

    Technetium-99 (Tc) displays a rich chemistry due to its wide range of accessible oxidation states (from -I to +VII) and ability to form coordination compounds. Determination of Tc speciation in complex mixtures is a major challenge, and (99)Tc nuclear magnetic resonance (NMR) spectroscopy is widely used to probe chemical environments of Tc in odd oxidation states. However, interpretation of (99)Tc NMR data is hindered by the lack of reference compounds. Density functional theory (DFT) calculations can help to fill this gap, but to date few computational studies have focused on (99)Tc NMR of compounds and complexes. This work evaluates the effectiveness of both pure generalized gradient approximation and their corresponding hybrid functionals, both with and without the inclusion of scalar relativistic effects, to model the (99)Tc NMR spectra of Tc(I) carbonyl compounds. With the exception of BLYP, which performed exceptionally well overall, hybrid functionals with inclusion of scalar relativistic effects are found to be necessary to accurately calculate (99)Tc NMR spectra. The computational method developed was used to tentatively assign an experimentally observed (99)Tc NMR peak at -1204 ppm to fac-Tc(CO)3(OH)3(2-). This study examines the effectiveness of DFT computations for interpretation of the (99)Tc NMR spectra of Tc(I) coordination compounds in high salt alkaline solutions. PMID:27518482

  9. A Measurement-Theoretic Analysis of the Fuzzy Logic Model of Perception.

    ERIC Educational Resources Information Center

    Crowther, Court S.; And Others

    1995-01-01

    The fuzzy logic model of perception (FLMP) is analyzed from a measurement-theoretic perspective. The choice rule of FLMP is shown to be equivalent to a version of the Rasch model. In fact, FLMP can be reparameterized as a simple two-category logit model. (SLD)

  10. Theoretical Studies of Proton-Coupled Electron Transfer: Models and Concepts Relevant to Bioenergetics

    PubMed Central

    Hatcher, Elizabeth; Ishikita, Hiroshi; Skone, Jonathan H.; Soudackov, Alexander V.

    2010-01-01

    Theoretical studies of proton-coupled electron transfer (PCET) reactions for model systems provide insight into fundamental concepts relevant to bioenergetics. A dynamical theoretical formulation for vibronically nonadiabatic PCET reactions has been developed. This theory enables the calculation of rates and kinetic isotope effects, as well as the pH and temperature dependences, of PCET reactions. Methods for calculating the vibronic couplings for PCET systems have also been developed and implemented. These theoretical approaches have been applied to a wide range of PCET reactions, including tyrosyl radical generation in a tyrosine-bound rhenium polypyridyl complex, phenoxyl/phenol and benzyl/toluene self-exchange reactions, and hydrogen abstraction catalyzed by the enzyme lipoxygenase. These applications have elucidated some of the key underlying physical principles of PCET reactions. The tools and concepts derived from these theoretical studies provide the foundation for future theoretical studies of PCET in more complex bioenergetic systems such as Photosystem II. PMID:21057592

  11. A beginner's guide to writing the nursing conceptual model-based theoretical rationale.

    PubMed

    Gigliotti, Eileen; Manister, Nancy N

    2012-10-01

    Writing the theoretical rationale for a study can be a daunting prospect for novice researchers. Nursing's conceptual models provide excellent frameworks for placement of study variables, but moving from the very abstract concepts of the nursing model to the less abstract concepts of the study variables is difficult. Similar to the five-paragraph essay used by writing teachers to assist beginning writers to construct a logical thesis, the authors of this column present guidelines that beginners can follow to construct their theoretical rationale. This guide can be used with any nursing conceptual model but Neuman's model was chosen here as the exemplar.

  12. Gender and Acceptance of E-Learning: A Multi-Group Analysis Based on a Structural Equation Model among College Students in Chile and Spain

    PubMed Central

    2015-01-01

    The scope of this study was to evaluate whether the adoption of e-learning in two universities, and in particular, the relationship between the perception of external control and perceived ease of use, is different because of gender differences. The study was carried out with participating students in two different universities, one in Chile and one in Spain. The Technology Acceptance Model was used as a theoretical framework for the study. A multi-group analysis method in partial least squares was employed to relate differences between groups. The four main conclusions of the study are: (1) a version of the Technology Acceptance Model has been successfully used to explain the process of adoption of e-learning at an undergraduate level of study; (2) the finding of a strong and significant relationship between perception of external control and perception of ease of use of the e-learning platform; (3) a significant relationship between perceived enjoyment and perceived ease of use and between results demonstrability and perceived usefulness is found; (4) the study indicates a few statistically significant differences between males and females when adopting an e-learning platform, according to the tested model. PMID:26465895

  13. Gender and Acceptance of E-Learning: A Multi-Group Analysis Based on a Structural Equation Model among College Students in Chile and Spain.

    PubMed

    Ramírez-Correa, Patricio E; Arenas-Gaitán, Jorge; Rondán-Cataluña, F Javier

    2015-01-01

    The scope of this study was to evaluate whether the adoption of e-learning in two universities, and in particular, the relationship between the perception of external control and perceived ease of use, is different because of gender differences. The study was carried out with participating students in two different universities, one in Chile and one in Spain. The Technology Acceptance Model was used as a theoretical framework for the study. A multi-group analysis method in partial least squares was employed to relate differences between groups. The four main conclusions of the study are: (1) a version of the Technology Acceptance Model has been successfully used to explain the process of adoption of e-learning at an undergraduate level of study; (2) the finding of a strong and significant relationship between perception of external control and perception of ease of use of the e-learning platform; (3) a significant relationship between perceived enjoyment and perceived ease of use and between results demonstrability and perceived usefulness is found; (4) the study indicates a few statistically significant differences between males and females when adopting an e-learning platform, according to the tested model.

  14. Gender and Acceptance of E-Learning: A Multi-Group Analysis Based on a Structural Equation Model among College Students in Chile and Spain.

    PubMed

    Ramírez-Correa, Patricio E; Arenas-Gaitán, Jorge; Rondán-Cataluña, F Javier

    2015-01-01

    The scope of this study was to evaluate whether the adoption of e-learning in two universities, and in particular, the relationship between the perception of external control and perceived ease of use, is different because of gender differences. The study was carried out with participating students in two different universities, one in Chile and one in Spain. The Technology Acceptance Model was used as a theoretical framework for the study. A multi-group analysis method in partial least squares was employed to relate differences between groups. The four main conclusions of the study are: (1) a version of the Technology Acceptance Model has been successfully used to explain the process of adoption of e-learning at an undergraduate level of study; (2) the finding of a strong and significant relationship between perception of external control and perception of ease of use of the e-learning platform; (3) a significant relationship between perceived enjoyment and perceived ease of use and between results demonstrability and perceived usefulness is found; (4) the study indicates a few statistically significant differences between males and females when adopting an e-learning platform, according to the tested model. PMID:26465895

  15. Stellar granulation as seen in disk-integrated intensity. I. Simplified theoretical modeling

    NASA Astrophysics Data System (ADS)

    Samadi, R.; Belkacem, K.; Ludwig, H.-G.

    2013-11-01

    Context. Solar granulation has been known for a long time to be a surface manifestation of convection. The space-borne missions CoRoT and Kepler enable us to observe the signature of this phenomena in disk-integrated intensity on a large number of stars. Aims: The space-based photometric measurements show that the global brightness fluctuations and the lifetime associated with granulation obeys characteristic scaling relations. We thus aimed at providing simple theoretical modeling to reproduce these scaling relations, and subsequently at inferring the physical properties of granulation across the Hertzsprung-Russell diagram. Methods: We developed a simple 1D theoretical model. The input parameters were extracted from 3D hydrodynamical models of the surface layers of stars, and the free parameters involved in the model were calibrated with solar observations. Two different prescriptions for representing the Fourier transform of the time-correlation of the eddy velocity were compared: a Lorentzian and an exponential form. Finally, we compared our theoretical prediction with 3D radiative hydrodynamical (RHD) numerical modeling of stellar granulation (hereafter ab initio approach). Results: Provided that the free parameters are appropriately adjusted, our theoretical model reproduces the observed solar granulation spectrum quite satisfactorily; the best agreement is obtained for an exponential form. Furthermore, our model results in granulation spectra that agree well with the ab initio approach using two 3D RHD models that are representative of the surface layers of an F-dwarf and a red-giant star. Conclusions: We have developed a theoretical model that satisfactory reproduces the solar granulation spectrum and gives results consistent with the ab initio approach. The model is used in a companion paper as theoretical framework for interpretating the observed scaling relations. Appendices are available in electronic form at http://www.aanda.org

  16. Single Droplet on Micro Square-Post Patterned Surfaces – Theoretical Model and Numerical Simulation

    PubMed Central

    Zu, Y. Q.; Yan, Y. Y.

    2016-01-01

    In this study, the wetting behaviors of single droplet on a micro square-post patterned surface with different geometrical parameters are investigated theoretically and numerically. A theoretical model is proposed for the prediction of wetting transition from the Cassie to Wenzel regimes. In addition, due to the limitation of theoretical method, a numerical simulation is performed, which helps get a view of dynamic contact lines, detailed velocity fields, etc., even if the droplet size is comparable with the scale of the surface micro-structures. It is found that the numerical results of the liquid drop behaviours on the square-post patterned surface are in good agreement with the predicted values by the theoretical model. PMID:26775561

  17. Single Droplet on Micro Square-Post Patterned Surfaces - Theoretical Model and Numerical Simulation.

    PubMed

    Zu, Y Q; Yan, Y Y

    2016-01-01

    In this study, the wetting behaviors of single droplet on a micro square-post patterned surface with different geometrical parameters are investigated theoretically and numerically. A theoretical model is proposed for the prediction of wetting transition from the Cassie to Wenzel regimes. In addition, due to the limitation of theoretical method, a numerical simulation is performed, which helps get a view of dynamic contact lines, detailed velocity fields, etc., even if the droplet size is comparable with the scale of the surface micro-structures. It is found that the numerical results of the liquid drop behaviours on the square-post patterned surface are in good agreement with the predicted values by the theoretical model.

  18. The Theory of Planned Behavior (TPB) and Pre-Service Teachers' Technology Acceptance: A Validation Study Using Structural Equation Modeling

    ERIC Educational Resources Information Center

    Teo, Timothy; Tan, Lynde

    2012-01-01

    This study applies the theory of planned behavior (TPB), a theory that is commonly used in commercial settings, to the educational context to explain pre-service teachers' technology acceptance. It is also interested in examining its validity when used for this purpose. It has found evidence that the TPB is a valid model to explain pre-service…

  19. Efficiency of the Technology Acceptance Model to Explain Pre-Service Teachers' Intention to Use Technology: A Turkish Study

    ERIC Educational Resources Information Center

    Teo, Timothy; Ursavas, Omer Faruk; Bahcekapili, Ekrem

    2011-01-01

    Purpose: The purpose of this study is to assess the efficiency of the technology acceptance model (TAM) to explain pre-service teachers' intention to use technology in Turkey. Design/methodology/approach: A total of 197 pre-service teachers from a Turkish university completed a survey questionnaire measuring their responses to four constructs…

  20. Factors of Online Learning Adoption: A Comparative Juxtaposition of the Theory of Planned Behaviour and the Technology Acceptance Model

    ERIC Educational Resources Information Center

    Ndubisi, Nelson

    2006-01-01

    Organisational investments in information technologies have increased significantly in the past few decades. All around the globe and in Malaysia particularly, a number of educational institutions are experimenting with e-learning. Adopting the theory of planned behaviour (TPB) and the technology acceptance model (TAM) this article tries to…

  1. A Quantitative Study of Faculty Perceptions and Attitudes on Asynchronous Virtual Teamwork Using the Technology Acceptance Model

    ERIC Educational Resources Information Center

    Wolusky, G. Anthony

    2016-01-01

    This quantitative study used a web-based questionnaire to assess the attitudes and perceptions of online and hybrid faculty towards student-centered asynchronous virtual teamwork (AVT) using the technology acceptance model (TAM) of Davis (1989). AVT is online student participation in a team approach to problem-solving culminating in a written…

  2. Validating the Technology Acceptance Model in the Context of the Laboratory Information System-Electronic Health Record Interface System

    ERIC Educational Resources Information Center

    Aquino, Cesar A.

    2014-01-01

    This study represents a research validating the efficacy of Davis' Technology Acceptance Model (TAM) by pairing it with the Organizational Change Readiness Theory (OCRT) to develop another extension to the TAM, using the medical Laboratory Information Systems (LIS)--Electronic Health Records (EHR) interface as the medium. The TAM posits that it is…

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

    NASA Technical Reports Server (NTRS)

    Hess, Ronald A.

    1991-01-01

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

  4. A Theoretical Model for Thin Film Ferroelectric Coupled Microstripline Phase Shifters

    NASA Technical Reports Server (NTRS)

    Romanofsky, R. R.; Quereshi, A. H.

    2000-01-01

    Novel microwave phase shifters consisting of coupled microstriplines on thin ferroelectric films have been demonstrated recently. A theoretical model useful for predicting the propagation characteristics (insertion phase shift, dielectric loss, impedance, and bandwidth) is presented here. The model is based on a variational solution for line capacitance and coupled strip transmission line theory.

  5. The Road Not Taken: An Integrative Theoretical Model of Reading Disability.

    ERIC Educational Resources Information Center

    Spear-Swerling, Louise; Sternberg, Robert J.

    1994-01-01

    This article describes a theoretical model of reading disability that integrates research findings in cognitive psychology, reading, and education. The model identifies four patterns of reading disability: (1) nonalphabetic readers, (2) compensatory readers, (3) nonautomatic readers, and (4) readers delayed in the acquisition of word recognition…

  6. Cross-Cultural Teamwork in End User Computing: A Theoretical Model.

    ERIC Educational Resources Information Center

    Bento, Regina F.

    1995-01-01

    Presents a theoretical model explaining how cultural influences may affect the open, dynamic system of a cross-cultural, end-user computing team. Discusses the relationship between cross-cultural factors and various parts of the model such as: input variables, the system itself, outputs, and implications for the management of such teams. (JKP)

  7. Undergraduate Engineering Students' Beliefs, Coping Strategies, and Academic Performance: An Evaluation of Theoretical Models

    ERIC Educational Resources Information Center

    Hsieh, Pei-Hsuan; Sullivan, Jeremy R.; Sass, Daniel A.; Guerra, Norma S.

    2012-01-01

    Research has identified factors associated with academic success by evaluating relations among psychological and academic variables, although few studies have examined theoretical models to understand the complex links. This study used structural equation modeling to investigate whether the relation between test anxiety and final course grades was…

  8. Achievement Goals and Discrete Achievement Emotions: A Theoretical Model and Prospective Test

    ERIC Educational Resources Information Center

    Pekrun, Reinhard; Elliot, Andrew J.; Maier, Markus A.

    2006-01-01

    A theoretical model linking achievement goals to discrete achievement emotions is proposed. The model posits relations between the goals of the trichotomous achievement goal framework and 8 commonly experienced achievement emotions organized in a 2 (activity/outcome focus) x 2 (positive/negative valence) taxonomy. Two prospective studies tested…

  9. Investigating IT Faculty Resistance to Learning Management System Adoption Using Latent Variables in an Acceptance Technology Model.

    PubMed

    Bousbahi, Fatiha; Alrazgan, Muna Saleh

    2015-01-01

    To enhance instruction in higher education, many universities in the Middle East have chosen to introduce learning management systems (LMS) to their institutions. However, this new educational technology is not being used at its full potential and faces resistance from faculty members. To investigate this phenomenon, we conducted an empirical research study to uncover factors influencing faculty members' acceptance of LMS. Thus, in the Fall semester of 2014, Information Technology faculty members were surveyed to better understand their perceptions of the incorporation of LMS into their courses. The results showed that personal factors such as motivation, load anxiety, and organizational support play important roles in the perception of the usefulness of LMS among IT faculty members. These findings suggest adding these constructs in order to extend the Technology acceptance model (TAM) for LMS acceptance, which can help stakeholders of the university to implement the use of this system. This may assist in planning and evaluating the use of e-learning.

  10. Investigating IT Faculty Resistance to Learning Management System Adoption Using Latent Variables in an Acceptance Technology Model.

    PubMed

    Bousbahi, Fatiha; Alrazgan, Muna Saleh

    2015-01-01

    To enhance instruction in higher education, many universities in the Middle East have chosen to introduce learning management systems (LMS) to their institutions. However, this new educational technology is not being used at its full potential and faces resistance from faculty members. To investigate this phenomenon, we conducted an empirical research study to uncover factors influencing faculty members' acceptance of LMS. Thus, in the Fall semester of 2014, Information Technology faculty members were surveyed to better understand their perceptions of the incorporation of LMS into their courses. The results showed that personal factors such as motivation, load anxiety, and organizational support play important roles in the perception of the usefulness of LMS among IT faculty members. These findings suggest adding these constructs in order to extend the Technology acceptance model (TAM) for LMS acceptance, which can help stakeholders of the university to implement the use of this system. This may assist in planning and evaluating the use of e-learning. PMID:26491712

  11. Investigating IT Faculty Resistance to Learning Management System Adoption Using Latent Variables in an Acceptance Technology Model

    PubMed Central

    Bousbahi, Fatiha; Alrazgan, Muna Saleh

    2015-01-01

    To enhance instruction in higher education, many universities in the Middle East have chosen to introduce learning management systems (LMS) to their institutions. However, this new educational technology is not being used at its full potential and faces resistance from faculty members. To investigate this phenomenon, we conducted an empirical research study to uncover factors influencing faculty members' acceptance of LMS. Thus, in the Fall semester of 2014, Information Technology faculty members were surveyed to better understand their perceptions of the incorporation of LMS into their courses. The results showed that personal factors such as motivation, load anxiety, and organizational support play important roles in the perception of the usefulness of LMS among IT faculty members. These findings suggest adding these constructs in order to extend the Technology acceptance model (TAM) for LMS acceptance, which can help stakeholders of the university to implement the use of this system. This may assist in planning and evaluating the use of e-learning. PMID:26491712

  12. 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. PMID:27242567

  13. 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

  14. 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.

  15. Using the UTAUT Model to Examine the Acceptance Behavior of Synchronous Collaboration to Support Peer Translation

    ERIC Educational Resources Information Center

    Liu, Yi Chun; Huang, Yong-Ming

    2015-01-01

    The teaching of translation has received considerable attention in recent years. Research on translation in collaborative learning contexts, however, has been less studied. In this study, we use a tool of synchronous collaboration to assist students in experiencing a peer translation process. Afterward, the unified theory of acceptance and use of…

  16. Adult Role Models: Feasibility, Acceptability, and Initial Outcomes for Sex Education

    ERIC Educational Resources Information Center

    Colarossi, Lisa; Silver, Ellen Johnson; Dean, Randa; Perez, Amanda; Rivera, Angelic

    2014-01-01

    The authors present the feasibility and acceptability of a parent sexuality education program led by peer educators in community settings. They also report the results of an outcome evaluation with 71 parents who were randomized to the intervention or a control group and surveyed one month prior to and six months after the four-week intervention.…

  17. Exploring Students' Intention to Use LINE for Academic Purposes Based on Technology Acceptance Model

    ERIC Educational Resources Information Center

    Van De Bogart, Willard; Wichadee, Saovapa

    2015-01-01

    The LINE application is often conceived as purely social space; however, the authors of this paper wanted to determine if it could be used for academic purposes. In this study, we examined how undergraduate students accepted LINE in terms of using it for classroom-related activities (e.g., submit homework, follow up course information queries,…

  18. Integrating Telemedicine for Disaster Response: Testing the Emergency Telemedicine Technology Acceptance Model

    ERIC Educational Resources Information Center

    Davis, Theresa M.

    2013-01-01

    Background: There is little evidence that technology acceptance is well understood in healthcare. The hospital environment is complex and dynamic creating a challenge when new technology is introduced because it impacts current processes and workflows which can significantly affect patient care delivery and outcomes. This study tested the effect…

  19. WebCT--The Quasimoderating Effect of Perceived Affective Quality on an Extending Technology Acceptance Model

    ERIC Educational Resources Information Center

    Sanchez-Franco, Manuel J.

    2010-01-01

    Perceived affective quality is an attractive area of research in Information System. Specifically, understanding the intrinsic and extrinsic individual factors and interaction effects that influence Information and Communications Technology (ICT) acceptance and adoption--in higher education--continues to be a focal interest in learning research.…

  20. An Investigation of University Student Readiness Towards M-Learning Using Technology Acceptance Model

    ERIC Educational Resources Information Center

    Iqbal, Shakeel; Bhatti, Zeeshan Ahmed

    2015-01-01

    M-learning is learning delivered via mobile devices and mobile technology. The research indicates that this medium of learning has potential to enhance formal as well as informal learning. However, acceptance of m-learning greatly depends upon the personal attitude of students towards this medium; therefore this study focuses only on the…

  1. Models and Messengers of Resilience: A Theoretical Model of College Students' Resilience, Regulatory Strategy Use, and Academic Achievement

    ERIC Educational Resources Information Center

    Johnson, Marcus L.; Taasoobshirazi, Gita; Kestler, Jessica L.; Cordova, Jackie R.

    2015-01-01

    We tested a theoretical model of college students' ratings of messengers of resilience and models of resilience, students' own perceived resilience, regulatory strategy use and achievement. A total of 116 undergraduates participated in this study. The results of a path analysis indicated that ratings of models of resilience had a direct effect on…

  2. Deriving Theoretical Boundaries to Address Domain and Resolution Dependencies of Triangle Models for Evapotranspiration Estimation

    NASA Astrophysics Data System (ADS)

    Long, D.; Singh, V. P.; Scanlon, B. R.

    2011-12-01

    Satellite-based triangle models for evapotranspiration (ET) are unique in interpreting the contextual relationship between Normalized Difference Vegetation Index (NDVI)/factional vegetation cover (fc) and surface radiative temperature (Trad) to deduce evaporative fraction (EF) and ET across large heterogeneous areas. The outputs and performance of some satellite-based ET algorithms may be dependent on the domain of a study site being considered and the resolution of satellite imagery being used. These attributes are referred to as domain dependence and resolution dependence. To unravel the domain and resolution dependencies of the triangle models and test the utility of the triangle models using high spatial resolution images, the triangle models were applied to areas with progressively growing domains and to Landsat TM/ETM+ and MODIS sensors, respectively, at the Soil Moisture-Atmosphere Coupling Experiment (SMACEX) site in central Iowa, U.S. on Day of Year (DOY) 174 and 182 in year 2002. Results indicate that the triangle models can be domain-dependent and resolution-dependent, showing large uncertainties in the evaporative fraction estimates in terms of a Mean Absolute Percentage Difference (MAPD) up to ~50%. We derived the theoretical boundaries of the fc-Trad space to restrain the domain and resolution dependencies of the triangle models. The theoretical warm edge was derived by solving for temperatures of the driest bare surface and the fully vegetated surface with the largest water stress implicit in both radiation budget and energy balance equations. The areal average temperature can be taken as the theoretical cold edge. The triangle models appear to perform well across large areas but fail to predict the evaporative fraction over small areas. However, performance of the triangle models across small domains can be improved by incorporating the theoretical boundaries. Combining the triangle models with the theoretical boundaries can effectively reduce

  3. Depression in Black Single Mothers: A Test of a Theoretical Model.

    PubMed

    Atkins, Rahshida

    2015-06-01

    The aim of this study was to test a theoretical model of depression for Black single mothers. Participants were 208 Black single mothers, aged 18 to 45, recruited from community settings. The a priori over-identified recursive theoretical model was tested via the LISREL 9.1 program using a maximum likelihood estimation for structural equation modeling. The chi-square indicated that there was an excellent fit of the model with the data, χ(2)(1, N = 208) = .05, p = .82. The fit indices for the model were excellent. Path coefficients were statistically significant for seven out of eight of the direct paths within the model (p < .05). The two indirect paths were also statistically significant. The theory was supported and can be applied by health care professionals when working with depressed Black single mothers.

  4. The calculation of theoretical chromospheric models and predicted OSO 1 spectra

    NASA Technical Reports Server (NTRS)

    Avrett, E. H.

    1975-01-01

    Theoretical solar chromospheric and photospheric models are computed for use in analyzing OSO 8 spectra. The Vernazza, Avrett, and Loeser (1976) solar model is updated and self-consistent non-LTE number densities for H I, He I, He II, C I, Mg I, Al I, Si I, and H(-) are produced. These number densities are used in the calculation of a theoretical solar spectrum from 90 to 250 nm, including approximately 7000 lines in non-LTE. More than 60,000 lines of other elements are treated with approximate source functions.

  5. On the theoretical model for vertical ozone density distributions in the mesosphere and upper stratosphere.

    NASA Technical Reports Server (NTRS)

    Shimazaki, T.; Wuebbles, D. J.

    1973-01-01

    Calculations based on an improved, time-dependent theoretical model for the vertical ozone density distribution in the upper atmosphere are shown to clarify the cause and determine the appearance precondition for the depression at the 70-85 km altitude region in the ozone density distribution suggested by several theoretical models and only sometimes experimentally observed. It is concluded that the depression develops at night through the effects of hydrogen-oxygen and nitrogen-oxygen reactions, as well as those of eddy diffusion transports.

  6. Test of the technology acceptance model for a Web-based information system in a Hong Kong Chinese sample.

    PubMed

    Cheung, Emily Yee Man; Sachs, John

    2006-12-01

    The modified technology acceptance model was used to predict actual Blackboard usage (a web-based information system) in a sample of 57 Hong Kong student teachers whose mean age was 27.8 yr. (SD = 6.9). While the general form of the model was supported, Application-specific Self-efficacy was a more powerful predictor of system use than Behavioural Intention as predicted by the theory of reasoned action. Thus in this cultural and educational context, it has been shown that the model does not fully mediate the effect of Self-efficacy on System Use. Also, users' Enjoyment exerted considerable influence on the component variables of Usefulness and Ease of Use and on Application-specific Self-efficacy, thus indirectly influencing system usage. Consequently, efforts to gain students' acceptance and, therefore, use of information systems such as Blackboard must pay adequate attention to users' Self-efficacy and motivational variables such as Enjoyment.

  7. Stress exposure and generation: A conjoint longitudinal model of body dysmorphic symptoms, peer acceptance, popularity, and victimization.

    PubMed

    Webb, Haley J; Zimmer-Gembeck, Melanie J; Mastro, Shawna

    2016-09-01

    This study examined the bidirectional (conjoint) longitudinal pathways linking adolescents' body dysmorphic disorder (BDD) symptoms with self- and peer-reported social functioning. Participants were 367 Australian students (45.5% boys, mean age=12.01 years) who participated in two waves of a longitudinal study with a 12-month lag between assessments. Participants self-reported their symptoms characteristic of BDD, and perception of peer acceptance. Classmates reported who was popular and victimized in their grade, and rated their liking (acceptance) of their classmates. In support of both stress exposure and stress generation models, T1 victimization was significantly associated with more symptoms characteristic of BDD at T2 relative to T1, and higher symptom level at T1 was associated with lower perceptions of peer acceptance at T2 relative to T1. These results support the hypothesized bidirectional model, whereby adverse social experiences negatively impact symptoms characteristic of BDD over time, and symptoms also exacerbate low perceptions of peer-acceptance. PMID:27236472

  8. Stress exposure and generation: A conjoint longitudinal model of body dysmorphic symptoms, peer acceptance, popularity, and victimization.

    PubMed

    Webb, Haley J; Zimmer-Gembeck, Melanie J; Mastro, Shawna

    2016-09-01

    This study examined the bidirectional (conjoint) longitudinal pathways linking adolescents' body dysmorphic disorder (BDD) symptoms with self- and peer-reported social functioning. Participants were 367 Australian students (45.5% boys, mean age=12.01 years) who participated in two waves of a longitudinal study with a 12-month lag between assessments. Participants self-reported their symptoms characteristic of BDD, and perception of peer acceptance. Classmates reported who was popular and victimized in their grade, and rated their liking (acceptance) of their classmates. In support of both stress exposure and stress generation models, T1 victimization was significantly associated with more symptoms characteristic of BDD at T2 relative to T1, and higher symptom level at T1 was associated with lower perceptions of peer acceptance at T2 relative to T1. These results support the hypothesized bidirectional model, whereby adverse social experiences negatively impact symptoms characteristic of BDD over time, and symptoms also exacerbate low perceptions of peer-acceptance.

  9. Using Theoretical Models to Examine the Acceptance Behavior of Mobile Phone Messaging to Enhance Parent-Teacher Interactions

    ERIC Educational Resources Information Center

    Ho, Li-Hsing; Hung, Chang-Liang; Chen, Hui-Chun

    2013-01-01

    Student academic performance and social competence are influenced positively by parent involvement; effective parent-teacher communication not builds parent reliance on a school, it enhances parent knowledge of raising children. As information technology develops rapidly, it is already a trend that e-communication is replacing traditional paper…

  10. A theoretical model to describe progressions and regressions for exercise rehabilitation.

    PubMed

    Blanchard, Sam; Glasgow, Phil

    2014-08-01

    This article aims to describe a new theoretical model to simplify and aid visualisation of the clinical reasoning process involved in progressing a single exercise. Exercise prescription is a core skill for physiotherapists but is an area that is lacking in theoretical models to assist clinicians when designing exercise programs to aid rehabilitation from injury. Historical models of periodization and motor learning theories lack any visual aids to assist clinicians. The concept of the proposed model is that new stimuli can be added or exchanged with other stimuli, either intrinsic or extrinsic to the participant, in order to gradually progress an exercise whilst remaining safe and effective. The proposed model maintains the core skills of physiotherapists by assisting clinical reasoning skills, exercise prescription and goal setting. It is not limited to any one pathology or rehabilitation setting and can adapted by any level of skilled clinician.

  11. Theoretical results on the tandem junction solar cell based on its Ebers-Moll transistor model

    NASA Technical Reports Server (NTRS)

    Goradia, C.; Vaughn, J.; Baraona, C. R.

    1980-01-01

    A one-dimensional theoretical model of the tandem junction solar cell (TJC) with base resistivity greater than about 1 ohm-cm and under low level injection has been derived. This model extends a previously published conceptual model which treats the TJC as an npn transistor. The model gives theoretical expressions for each of the Ebers-Moll type currents of the illuminated TJC and allows for the calculation of the spectral response, I(sc), V(oc), FF and eta under variation of one or more of the geometrical and material parameters and 1MeV electron fluence. Results of computer calculations based on this model are presented and discussed. These results indicate that for space applications, both a high beginning of life efficiency, greater than 15% AM0, and a high radiation tolerance can be achieved only with thin (less than 50 microns) TJC's with high base resistivity (greater than 10 ohm-cm).

  12. Postscript: Making Important Distinctions--Diagnostic Models, Theoretical Models, and the Mnemonic Model of PTSD

    ERIC Educational Resources Information Center

    Monroe, Scott M.; Mineka, Susan

    2008-01-01

    Our commentary was intended to stimulate discussion about what we perceive to be shortcomings of the mnemonic model and its research base, in the hope of shedding some light on key questions for understanding posttraumatic stress disorder (PTSD). In our view, Berntsen, Rubin, and Bohni have responded only to what they perceive to be shortcomings…

  13. A Physically Based Theoretical Model of Spore Deposition for Predicting Spread of Plant Diseases.

    PubMed

    Isard, Scott A; Chamecki, Marcelo

    2016-03-01

    A physically based theory for predicting spore deposition downwind from an area source of inoculum is presented. The modeling framework is based on theories of turbulence dispersion in the atmospheric boundary layer and applies only to spores that escape from plant canopies. A "disease resistance" coefficient is introduced to convert the theoretical spore deposition model into a simple tool for predicting disease spread at the field scale. Results from the model agree well with published measurements of Uromyces phaseoli spore deposition and measurements of wheat leaf rust disease severity. The theoretical model has the advantage over empirical models in that it can be used to assess the influence of source distribution and geometry, spore characteristics, and meteorological conditions on spore deposition and disease spread. The modeling framework is refined to predict the detailed two-dimensional spatial pattern of disease spread from an infection focus. Accounting for the time variations of wind speed and direction in the refined modeling procedure improves predictions, especially near the inoculum source, and enables application of the theoretical modeling framework to field experiment design. PMID:26595112

  14. A Physically Based Theoretical Model of Spore Deposition for Predicting Spread of Plant Diseases.

    PubMed

    Isard, Scott A; Chamecki, Marcelo

    2016-03-01

    A physically based theory for predicting spore deposition downwind from an area source of inoculum is presented. The modeling framework is based on theories of turbulence dispersion in the atmospheric boundary layer and applies only to spores that escape from plant canopies. A "disease resistance" coefficient is introduced to convert the theoretical spore deposition model into a simple tool for predicting disease spread at the field scale. Results from the model agree well with published measurements of Uromyces phaseoli spore deposition and measurements of wheat leaf rust disease severity. The theoretical model has the advantage over empirical models in that it can be used to assess the influence of source distribution and geometry, spore characteristics, and meteorological conditions on spore deposition and disease spread. The modeling framework is refined to predict the detailed two-dimensional spatial pattern of disease spread from an infection focus. Accounting for the time variations of wind speed and direction in the refined modeling procedure improves predictions, especially near the inoculum source, and enables application of the theoretical modeling framework to field experiment design.

  15. How parents choose to use CAM: a systematic review of theoretical models

    PubMed Central

    Lorenc, Ava; Ilan-Clarke, Yael; Robinson, Nicola; Blair, Mitch

    2009-01-01

    Background Complementary and Alternative Medicine (CAM) is widely used throughout the UK and the Western world. CAM is commonly used for children and the decision-making process to use CAM is affected by numerous factors. Most research on CAM use lacks a theoretical framework and is largely based on bivariate statistics. The aim of this review was to identify a conceptual model which could be used to explain the decision-making process in parental choice of CAM. Methods A systematic search of the literature was carried out. A two-stage selection process with predetermined inclusion/exclusion criteria identified studies using a theoretical framework depicting the interaction of psychological factors involved in the CAM decision process. Papers were critically appraised and findings summarised. Results Twenty two studies using a theoretical model to predict CAM use were included in the final review; only one examined child use. Seven different models were identified. The most commonly used and successful model was Andersen's Sociobehavioural Model (SBM). Two papers proposed modifications to the SBM for CAM use. Six qualitative studies developed their own model. Conclusion The SBM modified for CAM use, which incorporates both psychological and pragmatic determinants, was identified as the best conceptual model of CAM use. This model provides a valuable framework for future research, and could be used to explain child CAM use. An understanding of the decision making process is crucial in promoting shared decision making between healthcare practitioners and parents and could inform service delivery, guidance and policy. PMID:19386106

  16. Rethinking High School Principal Compensation Practices: An Analysis of Salaries in South Carolina and Theoretical Models

    ERIC Educational Resources Information Center

    Newman, Tim A.

    2012-01-01

    This study described the current state of principal salaries in South Carolina and compared the salaries of similar size schools by specific report card performance and demographic variables. Based on the findings, theoretical models were proposed, and comparisons were made with current salary data. School boards, human resource personnel and…

  17. Retaliation and antisocial punishment are overlooked in many theoretical models as well as behavioral experiments.

    PubMed

    Dreber, Anna; Rand, David G

    2012-02-01

    Guala argues that there is a mismatch between most laboratory experiments on costly punishment and behavior in the field. In the lab, experimental designs typically suppress retaliation. The same is true for most theoretical models of the co-evolution of costly punishment and cooperation, which a priori exclude the possibility of defectors punishing cooperators.

  18. Conceptualizing a Theoretical Model for School-Centered Adolescent Physical Activity Intervention Research

    ERIC Educational Resources Information Center

    Chen, Ang; Hancock, Gregory R.

    2006-01-01

    Adolescent physical inactivity has risen to an alarming rate. Several theoretical frameworks (models) have been proposed and tested in school-based interventions. The results are mixed, indicating a similar weakness as that observed in community-based physical activity interventions (Baranowski, Lin, Wetter, Resnicow, & Hearn, 1997). The…

  19. Unconscious Determinants of Career Choice and Burnout: Theoretical Model and Counseling Strategy.

    ERIC Educational Resources Information Center

    Malach-Pines, Ayala; Yafe-Yanai, Oreniya

    2001-01-01

    Proposes a psychodynamic-existential perspective as a theoretical model that explains career burnout and serves as a basis for a counseling strategy. According to existential theory, the root of career burnout lies in people's need to find existential significance in their life and their sense that their work does not provide it. (Contains 40…

  20. A Game-Theoretic Model of Grounding for Referential Communication Tasks

    ERIC Educational Resources Information Center

    Thompson, William

    2009-01-01

    Conversational grounding theory proposes that language use is a form of rational joint action, by which dialog participants systematically and collaboratively add to their common ground of shared knowledge and beliefs. Following recent work applying "game theory" to pragmatics, this thesis develops a game-theoretic model of grounding that…

  1. How Students Experience and Navigate Transitions in Undergraduate Medical Education: An Application of Bourdieu's Theoretical Model

    ERIC Educational Resources Information Center

    Balmer, Dorene F.; Richards, Boyd F.; Varpio, Lara

    2015-01-01

    Using Bourdieu's theoretical model as a lens for analysis, we sought to understand how students experience the undergraduate medical education (UME) milieu, focusing on how they navigate transitions from the preclinical phase, to the major clinical year (MCY), and to the preparation for residency phase. Twenty-two medical students participated in…

  2. On the Grammar and Model-Theoretic Semantics of Children's Noun Phrases.

    ERIC Educational Resources Information Center

    Suppes, Patrick

    The paper shows informally how model-theoretical semantics may be used by a computer to give a straight-forward analysis of the meaning of children's language. This approach to semantics grows out of the main thrust of work in mathematical logic. It is discussed in the framework of generative grammar and is based on the application of the…

  3. E-Learning Systems Support of Collaborative Agreements: A Theoretical Model

    ERIC Educational Resources Information Center

    Aguirre, Sandra; Quemada, Juan

    2012-01-01

    This paper introduces a theoretical model for developing integrated degree programmes through e-learning systems as stipulated by a collaboration agreement signed by two universities. We have analysed several collaboration agreements between universities at the national, European, and transatlantic level as well as various e-learning frameworks. A…

  4. Models of the Bilingual Lexicon and Their Theoretical Implications for CLIL

    ERIC Educational Resources Information Center

    Heine, Lena

    2014-01-01

    Although many advances have been made in recent years concerning the theoretical dimensions of content and language integrated learning (CLIL), research still has to meet the necessity to come up with integrative models that adequately map the interrelation between content and language learning in CLIL contexts. This article will suggest that…

  5. Education, Labour Market and Human Capital Models: Swedish Experiences and Theoretical Analyses.

    ERIC Educational Resources Information Center

    Sohlman, Asa

    An empirical study concerning development of the Swedish educational system from a labor market point of view, and a theoretical study on human capital models are discussed. In "Education and Labour Market; The Swedish Experience 1900-1975," attention is directed to the following concerns: the official educational policy regarding education and…

  6. Suggestion for a Theoretical Model for Secondary-Tertiary Transition in Mathematics

    ERIC Educational Resources Information Center

    Clark, Megan; Lovric, Miroslav

    2008-01-01

    One of most notable features of existing body of research in transition seems to be the absence of a theoretical model. The suggestion we present in this paper--to view and understand the high school to university transition in mathematics as a modern-day rite of passage--is an attempt at defining such framework. Although dominantly reflecting…

  7. Falling Chains as Variable-Mass Systems: Theoretical Model and Experimental Analysis

    ERIC Educational Resources Information Center

    de Sousa, Celia A.; Gordo, Paulo M.; Costa, Pedro

    2012-01-01

    In this paper, we revisit, theoretically and experimentally, the fall of a folded U-chain and of a pile-chain. The model calculation implies the division of the whole system into two subsystems of variable mass, allowing us to explore the role of tensional contact forces at the boundary of the subsystems. This justifies, for instance, that the…

  8. Predicting the Use of Paired Programming: Applying the Attitudes of Application Development Managers through the Technology Acceptance Model

    ERIC Educational Resources Information Center

    Zecca, Mark S.

    2010-01-01

    Business managers who look for ways to cut costs face difficult questions about the efficiency and effectiveness of software engineering practices that are used to complete projects on time, on specification, and within budget (Johnson, 1995; Lindstrom & Jeffries, 2004). Theoretical models such as the Theory of Reasoned Action (TRA) have linked…

  9. Fisherian and Wrightian perspectives in evolutionary genetics and model-mediated imposition of theoretical assumptions.

    PubMed

    Winther, Rasmus Grønfeldt

    2006-05-21

    I investigate how theoretical assumptions, pertinent to different perspectives and operative during the modeling process, are central in determining how nature is actually taken to be. I explore two different models by Michael Turelli and Steve Frank of the evolution of parasite-mediated cytoplasmic incompatility, guided, respectively, by Fisherian and Wrightian perspectives. Since the two models can be shown to be commensurable both with respect to mathematics and data, I argue that the differences between them in the (1) mathematical presentation of the models, (2) explanations, and (3) objectified ontologies stem neither from differences in mathematical method nor the employed data, but from differences in the theoretical assumptions, especially regarding ontology, already present in the respective perspectives. I use my "set up, mathematically manipulate, explain, and objectify" (SMEO) account of the modeling process to track the model-mediated imposition of theoretical assumptions. I conclude with a discussion of the general implications of my analysis of these models for the controversy between Fisherian and Wrightian perspectives. PMID:16263132

  10. Ocean color spectrum calculations. [theoretical models relating oceanographic parameters to upwelling radiances

    NASA Technical Reports Server (NTRS)

    Mccluney, W. R.

    1974-01-01

    The development is considered of procedures for measuring a number of subsurface oceanographic parameters using remotely sensed ocean color data. It is proposed that the first step in this effort should be the development of adequate theoretical models relating the desired oceanographic parameters to the upwelling radiances to be observed. A portion of a contributory theoretical model is shown to be described by a modified single scattering approach based upon a simple treatment of multiple scattering. The resulting quasi-single scattering model can be used to predict the upwelling distribution of spectral radiance emerging from the sea. The shape of the radiance spectrum predicted by this model for clear ocean water shows encouraging agreement with measurments made at the edge of the Sargasso Sea off Cape Hatteras.

  11. The Impact of Subjective Norm and Facilitating Conditions on Pre-Service Teachers' Attitude toward Computer Use: A Structural Equation Modeling of an Extended Technology Acceptance Model

    ERIC Educational Resources Information Center

    Teo, Timothy

    2009-01-01

    This study examined pre-service teachers' self-report on their attitude toward computer use. Participants were 285 pre-service teachers at a teacher training institution in Singapore. They completed a survey questionnaire measuring their responses to five constructs which formed a research model using the Technology Acceptance Model (TAM) as a…

  12. Rational Design of Lanthanoid Single-Ion Magnets: Predictive Power of the Theoretical Models.

    PubMed

    Baldoví, José J; Duan, Yan; Morales, Roser; Gaita-Ariño, Alejandro; Ruiz, Eliseo; Coronado, Eugenio

    2016-09-12

    We report two new single-ion magnets (SIMs) of a family of oxydiacetate lanthanide complexes with D3 symmetry to test the predictive capabilities of complete active space ab initio methods (CASSCF and CASPT2) and the semiempirical radial effective charge (REC) model. Comparison of the theoretical predictions of the energy levels, wave functions and magnetic properties with detailed spectroscopic and magnetic characterisation is used to critically discuss the limitations of these theoretical approaches. The need for spectroscopic information for a reliable description of the properties of lanthanide SIMs is emphasised. PMID:27465352

  13. Rational Design of Lanthanoid Single-Ion Magnets: Predictive Power of the Theoretical Models.

    PubMed

    Baldoví, José J; Duan, Yan; Morales, Roser; Gaita-Ariño, Alejandro; Ruiz, Eliseo; Coronado, Eugenio

    2016-09-12

    We report two new single-ion magnets (SIMs) of a family of oxydiacetate lanthanide complexes with D3 symmetry to test the predictive capabilities of complete active space ab initio methods (CASSCF and CASPT2) and the semiempirical radial effective charge (REC) model. Comparison of the theoretical predictions of the energy levels, wave functions and magnetic properties with detailed spectroscopic and magnetic characterisation is used to critically discuss the limitations of these theoretical approaches. The need for spectroscopic information for a reliable description of the properties of lanthanide SIMs is emphasised.

  14. Error control in the GCF: An information-theoretic model for error analysis and coding

    NASA Technical Reports Server (NTRS)

    Adeyemi, O.

    1974-01-01

    The structure of data-transmission errors within the Ground Communications Facility is analyzed in order to provide error control (both forward error correction and feedback retransmission) for improved communication. Emphasis is placed on constructing a theoretical model of errors and obtaining from it all the relevant statistics for error control. No specific coding strategy is analyzed, but references to the significance of certain error pattern distributions, as predicted by the model, to error correction are made.

  15. Experiments to test theoretical models of the polarization of light by rough surfaces

    NASA Technical Reports Server (NTRS)

    Geake, J. E.; Geake, M.; Zellner, B. H.

    1984-01-01

    A number of attempts have been made to provide theoretical models of the physical processes involved in the polarization of light scattered by a rough surface, such as the regolith of an atmosphereless planet. Some laboratory experiments designed to test different aspects of these models are described. It is concluded that double Fresnel reflection is usually the dominant process in producing negative polarization, but that diffraction effects may play a significant part in double events involving small-scale surface features.

  16. Theoretical analysis of triple concentric-tube heat exchangers. Part 1: Mathematical modelling

    SciTech Connect

    Uenal, A.

    1998-10-01

    A theoretical study consisting of two parts is conducted on triple concentric tube heat exchangers. This paper presents the first part of the study and deals with mathematical modeling. The model includes the derivation and possible solutions of the governing differential equations for both counter-flow and parallel-flow arrangements. In the second part of the study, which is under its way for publication, the results of several case studies will be presented.

  17. Cognitive-Existential Family Therapy: A Proposed Theoretical Integration Model for Pastoral Counselors.

    PubMed

    Saunders, James A

    2015-03-01

    Fundamental Christianity and psychology are frequently viewed as incompatible pursuits. However, proponents of the integrationist movement posit that pastoral counselors can utilize principles from psychology if they adopt the premise that all truth is God's truth. Assuming this perspective, Cognitive-Existential Family Therapy (CEFT) - a theoretical integration model compatible with Christian fundamentalism - is proposed. The philosophical assumptions and models of personality, health, and abnormality are explored. Additionally, the article provides an overview of the therapeutic process.

  18. Decision support models for solid waste management: Review and game-theoretic approaches

    SciTech Connect

    Karmperis, Athanasios C.; Aravossis, Konstantinos; Tatsiopoulos, Ilias P.; Sotirchos, Anastasios

    2013-05-15

    Highlights: ► The mainly used decision support frameworks for solid waste management are reviewed. ► The LCA, CBA and MCDM models are presented and their strengths, weaknesses, similarities and possible combinations are analyzed. ► The game-theoretic approach in a solid waste management context is presented. ► The waste management bargaining game is introduced as a specific decision support framework. ► Cooperative and non-cooperative game-theoretic approaches to decision support for solid waste management are discussed. - Abstract: This paper surveys decision support models that are commonly used in the solid waste management area. Most models are mainly developed within three decision support frameworks, which are the life-cycle assessment, the cost–benefit analysis and the multi-criteria decision-making. These frameworks are reviewed and their strengths and weaknesses as well as their critical issues are analyzed, while their possible combinations and extensions are also discussed. Furthermore, the paper presents how cooperative and non-cooperative game-theoretic approaches can be used for the purpose of modeling and analyzing decision-making in situations with multiple stakeholders. Specifically, since a waste management model is sustainable when considering not only environmental and economic but also social aspects, the waste management bargaining game is introduced as a specific decision support framework in which future models can be developed.

  19. Refinement and validation of two digital Microwave Landing System (MLS) theoretical models

    NASA Technical Reports Server (NTRS)

    Duff, W. G.; Guarino, C. R.

    1975-01-01

    Two digital microwave landing system theoretical models are considered which are generic models for the Doppler and scanning-beam frequency reference versions of the MLS. These models represent errors resulting from both system noise and discrete multipath. The data used for the validation effort were obtained from the Texas Instrument conventional scanning beam and the Hazeltine Doppler feasibility hardware versions of the MLS. Topics discussed include tape read software, time history plots, computation of power spectral density, smoothed power spectra, best-fit models, different equations for digital simulation, and discrete multipath errors.

  20. Theoretical models for near forward light scattering by a Plasmodium falciparum infected red blood cell

    NASA Astrophysics Data System (ADS)

    Sharma, S. K.

    2012-12-01

    A number of experimental elastic light scattering studies have been performed in the past few years with the aim of developing automated in vivo tools for differentiating a healthy red blood cell from a Plasmodium falciparum infected cell. This paper examines some theoretical aspects of the problem. An attempt has been made to simulate the scattering patterns of healthy as well as infected individual red blood cells. Two models, namely, a homogeneous sphere model and a coated sphere model have been considered. The scattering patterns predicted by these models are examined. A possible method for discriminating infected red blood cells from healthy ones has been suggested.

  1. A review of game-theoretic models of road user behaviour.

    PubMed

    Elvik, Rune

    2014-01-01

    This paper reviews game-theoretic models that have been developed to explain road user behaviour in situations where road users interact with each other. The paper includes the following game-theoretic models: 1.A general model of the interaction between road users and their possible reaction to measures improving safety (behavioural adaptation).2.Choice of vehicle size as a Prisoners’ dilemma game.3.Speed choice as a co-ordination game.4.Speed compliance as a game between drivers and the police.5.Merging into traffic from an acceleration lane as a mixed-strategy game.6.Choice of level of attention in following situations as an evolutionary game.7.Choice of departure time to avoid congestion as variant of a Prisoners’ dilemma game.8.Interaction between cyclists crossing the road and car drivers.9.Dipping headlights at night well ahead of the point when glare becomes noticeable.10.Choice of evasive action in a situation when cars are on collision course. The models reviewed are different in many respects, but a common feature of the models is that they can explain how informal norms of behaviour can develop among road users and be sustained even if these informal norms violate the formal regulations of the traffic code. Game-theoretic models are not applicable to every conceivable interaction between road users or to situations in which road users choose behaviour without interacting with other road users. Nevertheless, it is likely that game-theoretic models can be applied more widely than they have been until now.

  2. Theoretical model for torque differential magnetometry of single-domain magnets

    NASA Astrophysics Data System (ADS)

    Kamra, Akashdeep; Schreier, Michael; Huebl, Hans; Goennenwein, Sebastian T. B.

    2014-05-01

    We present a generic theoretical model for torque differential magnetometry (TDM)—an experimental method for determining the magnetic properties of a magnetic specimen by recording the resonance frequency of a mechanical oscillator, on which the magnetic specimen has been mounted, as a function of the applied magnetic field. The effective stiffness change, and hence the resonance frequency shift, of the oscillator due to the magnetic torque on the specimen is calculated, treating the magnetic specimen as a single magnetic domain. Our model can deal with an arbitrary magnetic free-energy density characterizing the specimen, as well as any relative orientation of the applied magnetic field, the specimen, and the oscillator. Our calculations agree well with published experimental data. The theoretical model presented here allows one to take full advantage of TDM as an efficient magnetometry method.

  3. Petri nets modeling and analysis using extended bag-theoretic relational algebra.

    PubMed

    Kim, Y C; Kim, T G

    1996-01-01

    Petri nets are a powerful modeling tool for studying reactive, concurrent systems. Analysis of the nets can reveal important information concerning the behavior of a modeled system. While various means for the analysis of the nets has been developed, a major limitation in the analysis, is explosion of large states space in simulation. An efficient method to manage large states space would overcome such a limitation. This paper proposes a framework for the modeling and analysis of Petri nets using relational database technologies. Formalism of the framework is based on a bag-theoretic relational algebra extended from the conventional, Within the framework, Petri nets are formalized by bag relations, and analysis algorithms are developed based on such formal relations. Properties associated with the nets are formalized by queries described in terms of the bag-theoretic relational algebra. The framework has been realized in a commercial relational database system using a standard SQL.

  4. Theoretical modeling of the catch-slip bond transition in biological adhesion

    NASA Astrophysics Data System (ADS)

    Gunnerson, Kim; Pereverzev, Yuriy; Prezhdo, Oleg

    2006-05-01

    The mechanism by which leukocytes leave the blood stream and enter inflamed tissue is called extravasation. This process is facilitated by the ability of selectin proteins, produced by the endothelial cells of blood vessels, to form transient bonds with the leukocytes. In the case of P-selectin, the protein bonds with P-selectin glycoprotein ligands (PSGL-1) produced by the leukocyte. Recent atomic force microscopy and flow chamber analyses of the binding of P-selectin to PSGL-1 provide evidence for an unusual biphasic catch-bond/slip-bond behavior in response to the strength of exerted force. This biphasic process is not well-understood. There are several theoretical models for describing this phenomenon. These models use different profiles for potential energy landscapes and how they change under forces. We are exploring these changes using molecular dynamics. We will present a simple theoretical model as well as share some of our early MD results for describing this phenomenon.

  5. New theoretical model and experiments on the leakage of refrigerant mixtures in a tank

    SciTech Connect

    Gao, Z.; Schreiber, W.; Ma, Y.

    1999-07-01

    A theoretical model of the isothermal leakage of refrigerant mixtures from a tank is presented. The model analyzes the isothermal leakage process of non-azeotropic mixture and the influence of leakage ratio on composition shift, vapor quality, and pressure. A simulation based on the model shows: (1) the composition shift caused by vapor leakage is more pronounced than by liquid leakage; (2) with the leakage ratio increasing, the composition shift trend varies with initial mass capacity, particularly when the leakage ratio is greater than 0.8; (3) the pressure drop is pronounced during the vapor leakage, but does not change during liquid leakage unless the leakage ratio is high. A series of leakage experiments are performed in a newly developed experimental system. The theoretical and experimental results match closely.

  6. [Sutureless hepatic transection using a new radiofrequency assisted device. Theoretical model, experimental study and clinic trial].

    PubMed

    Martínez-Serrano, María Ángeles; Grande, Luis; Burdío, Fernando; Berjano, Enrique; Poves, Ignasi; Quesada, Rita

    2011-03-01

    The ideal instrument for performing hepatic transection should combine safe and rapid haemostasis in a single tool. We present a new multidisciplinary investigation designed to develop a hepatic transection device assisted by radiofrequency (RF); the investigation included: a computerised theoretical model, and experimental study and a clinical trial of this device. The theoretic modelling was performed by computer, based on the Finite Elements Method (FEM), with the objective of studying the distribution of electrical energy and temperature in the tissue, and to assess the effect of the characteristics of the instrument. The experimental study, based on an in vivo porcine model, suggested that the new instrument would allow the transection velocity of the hepatic parenchyma to be increased with lower bleeding per transection area compared with other techniques extensively used in liver surgery. These data should enable the first phase of clinical trial to be conducted, with preliminary results that suggest that the new device is safe and effective.

  7. A novel scaffold geometry for chondral applications: theoretical model and in vivo validation.

    PubMed

    Scaglione, Silvia; Ceseracciu, Luca; Aiello, Maurizio; Coluccino, Luca; Ferrazzo, Federica; Giannoni, Paolo; Quarto, Rodolfo

    2014-10-01

    A theoretical model of the 3D scaffold internal architecture has been implemented with the aim to predict the effects of some geometrical parameters on total porosity, Young modulus, buckling resistance and permeability of the graft. This model has been adopted to produce porous poly-caprolacton based grafts for chondral tissue engineering applications, best tuning mechanical and functional features of the scaffolds. Material prototypes were produced with an internal geometry with parallel oriented cylindrical pores of 200 μm of radius (r) and an interpore distance/pores radius (d/r) ratio of 1. The scaffolds have been then extensively characterized; progenitor cells were then used to test their capability to support cartilaginous matrix deposition in an ectopic model. Scaffold prototypes fulfill both the chemical-physical requirements, in terms of Young's modulus and permeability, and the functional needs, such as surface area per volume and total porosity, for an enhanced cellular colonization and matrix deposition. Moreover, the grafts showed interesting chondrogenic potential in vivo, besides offering adequate mechanical performances in vitro, thus becoming a promising candidate for chondral tissues repair. Finally, a very good agreement was found between the prediction of the theoretical model and the experimental data. Many assumption of this theoretical model, hereby applied to cartilage, may be transposed to other tissue engineering applications, such as bone substitutes.

  8. Acceptance and Commitment Therapy for weight control: Model, evidence, and future directions

    PubMed Central

    Lillis, Jason; Kendra, Kathleen E.

    2014-01-01

    Behavioral weight loss programs achieve substantial short-term weight loss; however attrition and poor weight loss maintenance remain significant problems. Recently, Acceptance and Commitment Therapy (ACT) has been used in an attempt to improve long-term outcomes. This conceptual article outlines the standard behavioral and ACT approach to weight control, discusses potential benefits and obstacles to combing approaches, briefly reviews current ACT for weight control outcome research, and highlights significant empirical questions that remain. The current evidence suggests that ACT could be useful as an add-on treatment, or in a combined format, for improving long-term weight loss outcomes. Larger studies with longer follow-up are needed as well as studies that aim to identify how best to combine standard treatments and ACT and also who would benefit most from these approaches. PMID:25419510

  9. Students' Acceptance of Tablet PCs in the Classroom

    ERIC Educational Resources Information Center

    Ifenthaler, Dirk; Schweinbenz, Volker

    2016-01-01

    In recent years digital technologies, such as tablet personal computers (TPCs), have become an integral part of a school's infrastructure and are seen as a promising way to facilitate students' learning processes. This study empirically tested a theoretical model derived from the technology acceptance model containing key constructs developed in…

  10. A Knowledge Based Expert System to Aid Theoretical Ultrasonic Flaw Modelling

    NASA Astrophysics Data System (ADS)

    Robinson, Robert J.; McNab, Alistair

    2005-04-01

    This paper describes the culmination of three years work at the University of Strathclyde in developing an Expert System to aid theoretical flaw modelling. The Expert System utilises four validated models to simulate flaw modelling scenarios. Under certain conditions the models may break down and produce flaw responses which cannot be considered accurate. Previously a suitably qualified NDT engineer would have to interpret these results and update the original flaw model simulation in order to produce valid results. This was a laborious process and was restricted to those persons who had an in-depth knowledge in the operation of the validated models. The Expert System is capable of interpreting these warning flags and updating the original simulation to produce a valid modelling scenario. This paper gives a brief outline of how the Expert System operates before comparing the response of the system to that of a suitable qualified NDT engineer for a number of defect scenarios.

  11. Clusters of DNA induced by ionizing radiation: formation of short DNA fragments. I. Theoretical modeling

    NASA Technical Reports Server (NTRS)

    Holley, W. R.; Chatterjee, A.

    1996-01-01

    We have developed a general theoretical model for the interaction of ionizing radiation with chromatin. Chromatin is modeled as a 30-nm-diameter solenoidal fiber comprised of 20 turns of nucleosomes, 6 nucleosomes per turn. Charged-particle tracks are modeled by partitioning the energy deposition between primary track core, resulting from glancing collisions with 100 eV or less per event, and delta rays due to knock-on collisions involving energy transfers >100 eV. A Monte Carlo simulation incorporates damages due to the following molecular mechanisms: (1) ionization of water molecules leading to the formation of OH, H, eaq, etc.; (2) OH attack on sugar molecules leading to strand breaks: (3) OH attack on bases; (4) direct ionization of the sugar molecules leading to strand breaks; (5) direct ionization of the bases. Our calculations predict significant clustering of damage both locally, over regions up to 40 bp and over regions extending to several kilobase pairs. A characteristic feature of the regional damage predicted by our model is the production of short fragments of DNA associated with multiple nearby strand breaks. The shapes of the spectra of DNA fragment lengths depend on the symmetries or approximate symmetries of the chromatin structure. Such fragments have subsequently been detected experimentally and are reported in an accompanying paper (B. Rydberg, Radiat, Res. 145, 200-209, 1996) after exposure to both high- and low-LET radiation. The overall measured yields agree well quantitatively with the theoretical predictions. Our theoretical results predict the existence of a strong peak at about 85 bp, which represents the revolution period about the nucleosome. Other peaks at multiples of about 1,000 bp correspond to the periodicity of the particular solenoid model of chromatin used in these calculations. Theoretical results in combination with experimental data on fragmentation spectra may help determine the consensus or average structure of the

  12. Clusters of DNA induced by ionizing radiation: formation of short DNA fragments. I. Theoretical modeling.

    PubMed

    Holley, W R; Chatterjee, A

    1996-02-01

    We have developed a general theoretical model for the interaction of ionizing radiation with chromatin. Chromatin is modeled as a 30-nm-diameter solenoidal fiber comprised of 20 turns of nucleosomes, 6 nucleosomes per turn. Charged-particle tracks are modeled by partitioning the energy deposition between primary track core, resulting from glancing collisions with 100 eV or less per event, and delta rays due to knock-on collisions involving energy transfers >100 eV. A Monte Carlo simulation incorporates damages due to the following molecular mechanisms: (1) ionization of water molecules leading to the formation of OH, H, eaq, etc.; (2) OH attack on sugar molecules leading to strand breaks: (3) OH attack on bases; (4) direct ionization of the sugar molecules leading to strand breaks; (5) direct ionization of the bases. Our calculations predict significant clustering of damage both locally, over regions up to 40 bp and over regions extending to several kilobase pairs. A characteristic feature of the regional damage predicted by our model is the production of short fragments of DNA associated with multiple nearby strand breaks. The shapes of the spectra of DNA fragment lengths depend on the symmetries or approximate symmetries of the chromatin structure. Such fragments have subsequently been detected experimentally and are reported in an accompanying paper (B. Rydberg, Radiat, Res. 145, 200-209, 1996) after exposure to both high- and low-LET radiation. The overall measured yields agree well quantitatively with the theoretical predictions. Our theoretical results predict the existence of a strong peak at about 85 bp, which represents the revolution period about the nucleosome. Other peaks at multiples of about 1,000 bp correspond to the periodicity of the particular solenoid model of chromatin used in these calculations. Theoretical results in combination with experimental data on fragmentation spectra may help determine the consensus or average structure of the

  13. A note on Black-Scholes pricing model for theoretical values of stock options

    NASA Astrophysics Data System (ADS)

    Edeki, S. O.; Ugbebor, O. O.; Owoloko, E. A.

    2016-02-01

    In this paper, we consider some conditions that transform the classical Black-Scholes Model for stock options valuation from its partial differential equation (PDE) form to an equivalent ordinary differential equation (ODE) form. In addition, we propose a relatively new semi-analytical method for the solution of the transformed Black-Scholes model. The obtained solutions via this method can be used to find the theoretical values of the stock options in relation to their fair prices. In considering the reliability and efficiency of the models, we test some cases and the results are in good agreement with the exact solution.

  14. Two phase discharge of liquefied gases through pipes. Field experiments with ammonia and theoretical model

    NASA Astrophysics Data System (ADS)

    Nyren, K.; Winter, S.

    1984-01-01

    Field experiments with full scale releases of pressurized through siphon pipes from a storage tank were performed. It is found that the flow is a damped critical flow causing a violent turbulent spray jet. The pronounced atomization of the liquid and the quick air entrainment prevent rainout and no traces of land spills are observed. A theoretical model is also presented. Comparisons with the field experiments and laboratory experiments show that the model gives very good predictions of the mass flow rate and the jet determining parameters. The model is useful also for long pipe systems as it takes into account friction and other resistances.

  15. A theoretical model to predict tensile deformation behavior of balloon catheter.

    PubMed

    Todo, Mitsugu; Yoshiya, Keiji; Matsumoto, Takuya

    2016-09-01

    In this technical note, a simple theoretical model was proposed to express the tensile deformation and fracture of balloon catheter tested by the ISO standard using piece-wise linear force-displacement relations. The model was then validated by comparing with the tensile force-displacement behaviors of two types of typical balloon catheters clinically used worldwide. It was shown that the proposed model can effectively be used to express the tensile deformation behavior and easily be handled by physicians who are not familiar with mechanics of materials. PMID:27214691

  16. Field-theoretic model of inhomogeneous supramolecular polymer networks and gels

    NASA Astrophysics Data System (ADS)

    Mohan, Aruna; Elliot, Richard; Fredrickson, Glenn H.

    2010-11-01

    We present a field-theoretic model of the gelation transition in inhomogeneous reversibly bonding systems and demonstrate that our model reproduces the classical Flory-Stockmayer theory of gelation in the homogeneous limit. As an illustration of our model in the context of inhomogeneous gelation, we analyze the mean-field behavior of an equilibrium system of reacting trifunctional units in a good solvent confined within a slit bounded by parallel, repulsive walls. Our results indicate higher conversions and, consequently, higher concentrations of gel following the gelation transition near the center of the slit relative to the edges.

  17. Field-theoretic model of inhomogeneous supramolecular polymer networks and gels.

    PubMed

    Mohan, Aruna; Elliot, Richard; Fredrickson, Glenn H

    2010-11-01

    We present a field-theoretic model of the gelation transition in inhomogeneous reversibly bonding systems and demonstrate that our model reproduces the classical Flory-Stockmayer theory of gelation in the homogeneous limit. As an illustration of our model in the context of inhomogeneous gelation, we analyze the mean-field behavior of an equilibrium system of reacting trifunctional units in a good solvent confined within a slit bounded by parallel, repulsive walls. Our results indicate higher conversions and, consequently, higher concentrations of gel following the gelation transition near the center of the slit relative to the edges. PMID:21054065

  18. [Nursing and the environmental question: proposal of a theoretical model for the professional practice].

    PubMed

    Ribeiro, M C; Bertolozzi, M R

    1999-01-01

    Considering the side effects of environmental changes over the population's health, a theoretical model is proposed in this study in order to incorporate ecologic matters into the nursing practices. The reference for this work is the eco-socialist-marxist theory. The model is based on the analysis of the capitalist economic process, its production technologies and consumption. It is known that this economic model generates ecoinequalities and anthropogenic impacts that rebound on the health-disease profile of the population. The nursing action, permeated by ecological awareness, can prevent and also combat ecoinequalities and destructive human actions on the environment. PMID:12138633

  19. Deriving theoretical boundaries to address scale dependencies of triangle models for evapotranspiration estimation

    NASA Astrophysics Data System (ADS)

    Long, Di; Singh, Vijay P.; Scanlon, Bridget R.

    2012-03-01

    Satellite-based triangle models for evapotranspiration estimation are unique in interpreting the relationship between the normalized difference vegetation index (NDVI)/factional vegetation cover (fc) and surface radiative temperature (Trad) across large heterogeneous areas. However, output and performance of triangle models may depend on the size of the domain being studied and resolution of the satellite images being used. The objective of this study was to assess domain and resolution dependencies of triangle models using progressively larger domains and Landsat Thematic Mapper/Enhanced Thematic Mapper Plus and Moderate Resolution Imaging Spectroradiometer sensors at the Soil Moisture-Atmosphere Coupling Experiment site in central Iowa on days of year 174 and 182 in 2002. Results show domain and resolution dependencies of the triangle models with large uncertainties in evaporative fraction (EF) estimates in terms of a mean absolute percentage difference (MAPD) up to ˜50%. A trapezoid model which requires derivation of theoretical limiting edges of the NDVI-Trad space is proposed to constrain domain and resolution dependencies of triangle models. The theoretical warm edge can be derived by solving for temperatures of the driest bare surface and the fully vegetated surface with the largest water stress implicit in both radiation budget and energy balance equations. Areal average air temperature can be taken as the theoretical cold edge. The triangle model appears to perform well across large areas (˜104 km2) but fails to predict EF over small areas (˜102 km2). The trapezoid model can effectively reduce domain and resolution dependencies and constrain errors of the EF estimates with an MAPD of ˜10%.

  20. An information-theoretic model for link prediction in complex networks

    PubMed Central

    Zhu, Boyao; Xia, Yongxiang

    2015-01-01

    Various structural features of networks have been applied to develop link prediction methods. However, because different features highlight different aspects of network structural properties, it is very difficult to benefit from all of the features that might be available. In this paper, we investigate the role of network topology in predicting missing links from the perspective of information theory. In this way, the contributions of different structural features to link prediction are measured in terms of their values of information. Then, an information-theoretic model is proposed that is applicable to multiple structural features. Furthermore, we design a novel link prediction index, called Neighbor Set Information (NSI), based on the information-theoretic model. According to our experimental results, the NSI index performs well in real-world networks, compared with other typical proximity indices. PMID:26335758

  1. Theoretical modeling of the plasma-assisted catalytic growth and field emission properties of graphene sheet

    SciTech Connect

    Sharma, Suresh C.; Gupta, Neha

    2015-12-15

    A theoretical modeling for the catalyst-assisted growth of graphene sheet in the presence of plasma has been investigated. It is observed that the plasma parameters can strongly affect the growth and field emission properties of graphene sheet. The model developed accounts for the charging rate of the graphene sheet; number density of electrons, ions, and neutral atoms; various elementary processes on the surface of the catalyst nanoparticle; surface diffusion and accretion of ions; and formation of carbon-clusters and large graphene islands. In our investigation, it is found that the thickness of the graphene sheet decreases with the plasma parameters, number density of hydrogen ions and RF power, and consequently, the field emission of electrons from the graphene sheet surface increases. The time evolution of the height of graphene sheet with ion density and sticking coefficient of carbon species has also been examined. Some of our theoretical results are in compliance with the experimental observations.

  2. Advancing Women Scientists: Exploring a Theoretically Grounded Climate Change Workshop Model

    NASA Astrophysics Data System (ADS)

    Silver, Barbara; Prochaska, Janice; Mederer, Helen; Harlow, Lisa; Sherman, Karen

    Universities in the United States have an increasing need to recruit the best and the brightest faculty to remain globally competitive, but the majority of schools share a profile that includes a low percentage of women in most of the science, technology, engineering, and math (STEM) disciplines. Changes in university culture are needed to enable departmental diversity growth, to expand offerings and perspectives, and to strengthen the view that STEM is an attractive choice for female students and prospective faculty. This paper describes the theoretical models used to develop a prototype workshop series implemented in departments to help faculty progress in their readiness to advance women scientists, defined as collaborating, mentoring, sharing resources, and generating support through community. The three theoretical underpinnings are the gender-as-structure theory of organizational change, Appreciative Inquiry, and the Transtheoretical Model. These workshops are one aspect of the climate change efforts implemented by the ADVANCE program of the University of Rhode Island.

  3. Acceptance and commitment therapy (ACT): the foundation of the therapeutic model and an overview of its contribution to the treatment of patients with chronic physical diseases.

    PubMed

    Prevedini, Anna Bianca; Presti, Giovambattista; Rabitti, Elisa; Miselli, Giovanni; Moderato, Paolo

    2011-01-01

    Nowadays, treatment of chronic illnesses, such as stroke, cancer, chronic heart and respiratory diseases, osteoarthritis, diabetes, and so forth, account for the largest part of expenses in western countries national health systems. Moreover, these diseases are by far the leading causes of mortality in the world, representing 60% of all deaths. Any treatment aimed at targeting them might engage an individual for a large portion of his/her life so that personal and environmental factors can play a crucial role in modulating the person's quality of life and functioning, on top of any medical cure. Anxiety, depression, and distress for examples are not rare in patients with chronic diseases. Therefore, Cognitive and Behavior Therapy research has largely contributed in the last decades in identifying and programming interventions on such aspects as real and perceived social and family support, coping abilities, locus of control, self-efficacy that might help patients living with their chronic disease. More recently, third generation Cognitive-Behavior-Therapies, such as Dialectical Behavioral Therapy (DBT), Mindfulness Based Cognitive Therapy (MBCT), Functional Analytic Psychotherapy (FAP) and Acceptance, and Commitment Therapy (ACT) focused their attention and research efforts on developing intervention models targeting the needs of patients with a chronic disease. This paper has three aims. First is to briefly introduce ACT epistemological (Functional Contextualism) and theoretical (Relational Frame Theory) foundations as a stand point for understanding the peculiarity of ACT as a modern form of Clinical Behavior Analysis. The second aim is to introduce ACT clinical model and its six core processes (acceptance, defusion, present moment, self as a context, values and committed action) as both accountable, in their continuum, for psychological flexibility and inflexibility. Third, to present a brief overview of studies and outcomes of ACT intervention protocols and

  4. A theoretical model for the cross spectra between pressure and temperature downstream of a combustor

    NASA Technical Reports Server (NTRS)

    Miles, J. H.; Krejsa, E. A.

    1984-01-01

    A theoretical model developed to calculate pressure-temperature cross spectra, pressure spectra, temperature spectra and pressure cross spectra in a ducted combustion system is presented. The model assumes the presence of a fluctuating-volumetric-heat-release-rate disk source and takes into account the spatial distribution of the steady-state volumetric-heat flux. Using the model, pressure, velocity, and temperature perturbation relationships can be obtained. The theoretical results show that, at a given air mass flow rate, the calculated pressure-temperature cross spectra phase angle at the combustor exit depends on the model selected for the steady-state volumetric-heat flux in the combustor. Using measurements of the phase angle, an appropriate source region model was selected. The model calculations are compared with the data. The comparison shows good agreement and indicates that with the use of this model the pressure-temperature cross spectra measurements provide useful information on the physical mechanisms active at the combustion noise source.

  5. Dynamical gap generation in graphene nanoribbons: An effective relativistic field theoretical model

    SciTech Connect

    Chaves, A. J.; Paula, W. de; Frederico, T.; Lima, G. D.; Cordeiro, C. E.; Delfino, A.

    2011-04-15

    We show that the assumption of a nontrivial zero band gap for a graphene sheet within an effective relativistic field theoretical model description of interacting Dirac electrons on the surface of graphene describes the experimental band gap of graphene nanoribbons for a wide range of widths. The graphene band gap is dynamically generated, corresponding to a nontrivial gapless solution, found in the limit of an infinitely wide graphene ribbon. The nanoribbon band gap is determined by the experimental graphene work function.

  6. An Empirical Analysis of Citizens' Acceptance Decisions of Electronic-Government Services: A Modification of the Unified Theory of Acceptance and Use of Technology (UTAUT) Model to Include Trust as a Basis for Investigation

    ERIC Educational Resources Information Center

    Awuah, Lawrence J.

    2012-01-01

    Understanding citizens' adoption of electronic-government (e-government) is an important topic, as the use of e-government has become an integral part of governance. Success of such initiatives depends largely on the efficient use of e-government services. The unified theory of acceptance and use of technology (UTAUT) model has provided a…

  7. Meta-Theoretical Contributions to the Constitution of a Model-Based Didactics of Science

    NASA Astrophysics Data System (ADS)

    Ariza, Yefrin; Lorenzano, Pablo; Adúriz-Bravo, Agustín

    2016-07-01

    There is nowadays consensus in the community of didactics of science (i.e. science education understood as an academic discipline) regarding the need to include the philosophy of science in didactical research, science teacher education, curriculum design, and the practice of science education in all educational levels. Some authors have identified an ever-increasing use of the concept of `theoretical model', stemming from the so-called semantic view of scientific theories. However, it can be recognised that, in didactics of science, there are over-simplified transpositions of the idea of model (and of other meta-theoretical ideas). In this sense, contemporary philosophy of science is often blurred or distorted in the science education literature. In this paper, we address the discussion around some meta-theoretical concepts that are introduced into didactics of science due to their perceived educational value. We argue for the existence of a `semantic family', and we characterise four different versions of semantic views existing within the family. In particular, we seek to contribute to establishing a model-based didactics of science mainly supported in this semantic family.

  8. Representing general theoretical concepts in structural equation models: The role of composite variables

    USGS Publications Warehouse

    Grace, J.B.; Bollen, K.A.

    2008-01-01

    Structural equation modeling (SEM) holds the promise of providing natural scientists the capacity to evaluate complex multivariate hypotheses about ecological systems. Building on its predecessors, path analysis and factor analysis, SEM allows for the incorporation of both observed and unobserved (latent) variables into theoretically-based probabilistic models. In this paper we discuss the interface between theory and data in SEM and the use of an additional variable type, the composite. In simple terms, composite variables specify the influences of collections of other variables and can be helpful in modeling heterogeneous concepts of the sort commonly of interest to ecologists. While long recognized as a potentially important element of SEM, composite variables have received very limited use, in part because of a lack of theoretical consideration, but also because of difficulties that arise in parameter estimation when using conventional solution procedures. In this paper we present a framework for discussing composites and demonstrate how the use of partially-reduced-form models can help to overcome some of the parameter estimation and evaluation problems associated with models containing composites. Diagnostic procedures for evaluating the most appropriate and effective use of composites are illustrated with an example from the ecological literature. It is argued that an ability to incorporate composite variables into structural equation models may be particularly valuable in the study of natural systems, where concepts are frequently multifaceted and the influence of suites of variables are often of interest. ?? Springer Science+Business Media, LLC 2007.

  9. Information-theoretic model-averaged benchmark dose analysis in environmental risk assessment

    PubMed Central

    Piegorsch, Walter W.; An, Lingling; Wickens, Alissa A.; West, R. Webster; Peña, Edsel A.; Wu, Wensong

    2013-01-01

    An important objective in environmental risk assessment is estimation of minimum exposure levels, called Benchmark Doses (BMDs), that induce a pre-specified Benchmark Response (BMR) in a dose-response experiment. In such settings, representations of the risk are traditionally based on a specified parametric model. It is a well-known concern, however, that existing parametric estimation techniques are sensitive to the form employed for modeling the dose response. If the chosen parametric model is in fact misspecified, this can lead to inaccurate low-dose inferences. Indeed, avoiding the impact of model selection was one early motivating issue behind development of the BMD technology. Here, we apply a frequentist model averaging approach for estimating benchmark doses, based on information-theoretic weights. We explore how the strategy can be used to build one-sided lower confidence limits on the BMD, and we study the confidence limits’ small-sample properties via a simulation study. An example from environmental carcinogenicity testing illustrates the calculations. It is seen that application of this information-theoretic, model averaging methodology to benchmark analysis can improve environmental health planning and risk regulation when dealing with low-level exposures to hazardous agents. PMID:24039461

  10. Thermal conductivity of molten salt mixtures: Theoretical model supported by equilibrium molecular dynamics simulations.

    PubMed

    Gheribi, Aïmen E; Chartrand, Patrice

    2016-02-28

    A theoretical model for the description of thermal conductivity of molten salt mixtures as a function of composition and temperature is presented. The model is derived by considering the classical kinetic theory and requires, for its parametrization, only information on thermal conductivity of pure compounds. In this sense, the model is predictive. For most molten salt mixtures, no experimental data on thermal conductivity are available in the literature. This is a hindrance for many industrial applications (in particular for thermal energy storage technologies) as well as an obvious barrier for the validation of the theoretical model. To alleviate this lack of data, a series of equilibrium molecular dynamics (EMD) simulations has been performed on several molten chloride systems in order to determine their thermal conductivity in the entire range of composition at two different temperatures: 1200 K and 1300 K. The EMD simulations are first principles type, as the potentials used to describe the interactions have been parametrized on the basis of first principle electronic structure calculations. In addition to the molten chlorides system, the model predictions are also compared to a recent similar EMD study on molten fluorides and with the few reliable experimental data available in the literature. The accuracy of the proposed model is within the reported numerical and/or experimental errors.

  11. Thermal conductivity of molten salt mixtures: Theoretical model supported by equilibrium molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Gheribi, Aïmen E.; Chartrand, Patrice

    2016-02-01

    A theoretical model for the description of thermal conductivity of molten salt mixtures as a function of composition and temperature is presented. The model is derived by considering the classical kinetic theory and requires, for its parametrization, only information on thermal conductivity of pure compounds. In this sense, the model is predictive. For most molten salt mixtures, no experimental data on thermal conductivity are available in the literature. This is a hindrance for many industrial applications (in particular for thermal energy storage technologies) as well as an obvious barrier for the validation of the theoretical model. To alleviate this lack of data, a series of equilibrium molecular dynamics (EMD) simulations has been performed on several molten chloride systems in order to determine their thermal conductivity in the entire range of composition at two different temperatures: 1200 K and 1300 K. The EMD simulations are first principles type, as the potentials used to describe the interactions have been parametrized on the basis of first principle electronic structure calculations. In addition to the molten chlorides system, the model predictions are also compared to a recent similar EMD study on molten fluorides and with the few reliable experimental data available in the literature. The accuracy of the proposed model is within the reported numerical and/or experimental errors.

  12. Thermal conductivity of molten salt mixtures: Theoretical model supported by equilibrium molecular dynamics simulations.

    PubMed

    Gheribi, Aïmen E; Chartrand, Patrice

    2016-02-28

    A theoretical model for the description of thermal conductivity of molten salt mixtures as a function of composition and temperature is presented. The model is derived by considering the classical kinetic theory and requires, for its parametrization, only information on thermal conductivity of pure compounds. In this sense, the model is predictive. For most molten salt mixtures, no experimental data on thermal conductivity are available in the literature. This is a hindrance for many industrial applications (in particular for thermal energy storage technologies) as well as an obvious barrier for the validation of the theoretical model. To alleviate this lack of data, a series of equilibrium molecular dynamics (EMD) simulations has been performed on several molten chloride systems in order to determine their thermal conductivity in the entire range of composition at two different temperatures: 1200 K and 1300 K. The EMD simulations are first principles type, as the potentials used to describe the interactions have been parametrized on the basis of first principle electronic structure calculations. In addition to the molten chlorides system, the model predictions are also compared to a recent similar EMD study on molten fluorides and with the few reliable experimental data available in the literature. The accuracy of the proposed model is within the reported numerical and/or experimental errors. PMID:26931711

  13. Reality-Theoretical Models-Mathematics: A Ternary Perspective on Physics Lessons in Upper-Secondary School

    ERIC Educational Resources Information Center

    Hansson, Lena; Hansson, Örjan; Juter, Kristina; Redfors, Andreas

    2015-01-01

    This article discusses the role of mathematics during physics lessons in upper-secondary school. Mathematics is an inherent part of theoretical models in physics and makes powerful predictions of natural phenomena possible. Ability to use both theoretical models and mathematics is central in physics. This paper takes as a starting point that the…

  14. 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…

  15. Theoretic aspects of the identification of the parameters in the optimal control model

    NASA Technical Reports Server (NTRS)

    Vanwijk, R. A.; Kok, J. J.

    1977-01-01

    The identification of the parameters of the optimal control model from input-output data of the human operator is considered. Accepting the basic structure of the model as a cascade of a full-order observer and a feedback law, and suppressing the inherent optimality of the human controller, the parameters to be identified are the feedback matrix, the observer gain matrix, and the intensity matrices of the observation noise and the motor noise. The identification of the parameters is a statistical problem, because the system and output are corrupted by noise, and therefore the solution must be based on the statistics (probability density function) of the input and output data of the human operator. However, based on the statistics of the input-output data of the human operator, no distinction can be made between the observation and the motor noise, which shows that the model suffers from overparameterization.

  16. A theoretical model for the prediction of vertical axis wind turbine performance

    NASA Astrophysics Data System (ADS)

    Fortunato, B.; Dadone, A.; Trifoni, V.

    1993-01-01

    The present paper provides a two-dimensional model for the computation of the flow field around vertical axis wind turbines. The model considers the effect of the blades in a time averaged sense by means of an actuator porous cylinder, having the turbine radius. The numerical method here employed is the 'fast solver', which is a natural extension of the classical lambda formulation and is based on the integration of the compatibility conditions along bicharacteristic lines. The vertical axis wind turbine performance obtained with the present method are compared with other theoretical and experimental results.

  17. Theoretical modelling of the feedback stabilization of external MHD modes in toroidal geometry

    NASA Astrophysics Data System (ADS)

    Chance, M. S.; Chu, M. S.; Okabayashi, M.; Turnbull, A. D.

    2002-03-01

    A theoretical framework for understanding the feedback mechanism for stabilization of external MHD modes has been formulated. Efficient computational tools - the GATO stability code coupled with a substantially modified VACUUM code - have been developed to effectively design viable feedback systems against these modes. The analysis assumed a thin resistive shell and a feedback coil structure accurately modelled in θ and phi, albeit with only a single harmonic variation in phi. Time constants and induced currents in the enclosing resistive shell are calculated. An optimized configuration based on an idealized model has been computed for the DIII-D device. Up to 90% of the effectiveness of an ideal wall can be achieved.

  18. The bootstrapped model--Lessons for the acceptance of intellectual technology.

    PubMed

    Lovie, A D

    1987-09-01

    This paper is intended as a non-technical introduction to a growing aspect of what has been termed 'intellectual technology'. The particular area chosen is the use of simple linear additive models for judgement and decision making purposes. Such models are said to either outperform, or perform at least as well as, the human judges on which they are based, hence they are said to 'bootstrap' such human inputs. Although the paper will provide a fairly comprehensive list of recent applications of such models, from postgraduate selection to judgements of marital happiness, the work will concentrate on the topic of Credit Scoring as an exemplar - that is, the assignment of credit by means of a simple additive rule. The paper will also present a simple system, due to Dawes, of classifying such models according to the form and source of their weights. The paper further discusses the reasons for bootstrapping and that other major phenomenon of such models - that is, the one can rarely distinguish between the prescriptions of such models, however the weights have been arrived at. It is argued that this 'principle of the flat maximum' allows us to develop a technology of judgement. The paper continues with a brief historical survey of the reactions of human experts to such models and their superiority, and suggestions for a better mix of expert and model on human engineering lines. Finally, after a brief comparison between expert systems and linear additive models, the paper concludes with a brief survey of possible future developments. A short Appendix describes two applications of such models.

  19. Theoretical Model of God: The Key to Correct Exploration of the Universe

    NASA Astrophysics Data System (ADS)

    Kalanov, Temur Z.

    2007-04-01

    The problem of the correct approach to exploration of the Universe cannot be solved if there is no solution of the problem of existence of God (Creator, Ruler) in science. In this connection, theoretical proof of existence of God is proposed. The theoretical model of God -- as scientific proof of existence of God -- is the consequence of the system of the formulated axioms. The system of the axioms contains, in particular, the following premises: (1) all objects formed (synthesized) by man are characterized by the essential property: namely, divisibility into aspects; (2) objects which can be mentally divided into aspects are objects formed (synthesized); (3) the system ``Universe'' is mentally divided into aspects. Consequently, the Universe represents the system formed (synthesized); (4) the theorem of existence of God (i.e. Absolute, Creator, Ruler) follows from the principle of logical completeness of system of concepts: if the formed (synthesized) system ``Universe'' exists, then God exists as the Absolute, the Creator, the Ruler of essence (i.e. information) and phenomenon (i.e. material objects). Thus, the principle of existence of God -- the content of the theoretical model of God -- must be a starting-point and basis of correct gnosiology and science of 21 century.

  20. Theoretical foundation, methods, and criteria for calibrating human vibration models using frequency response functions

    PubMed Central

    Dong, Ren G.; Welcome, Daniel E.; McDowell, Thomas W.; Wu, John Z.

    2015-01-01

    While simulations of the measured biodynamic responses of the whole human body or body segments to vibration are conventionally interpreted as summaries of biodynamic measurements, and the resulting models are considered quantitative, this study looked at these simulations from a different angle: model calibration. The specific aims of this study are to review and clarify the theoretical basis for model calibration, to help formulate the criteria for calibration validation, and to help appropriately select and apply calibration methods. In addition to established vibration theory, a novel theorem of mechanical vibration is also used to enhance the understanding of the mathematical and physical principles of the calibration. Based on this enhanced understanding, a set of criteria was proposed and used to systematically examine the calibration methods. Besides theoretical analyses, a numerical testing method is also used in the examination. This study identified the basic requirements for each calibration method to obtain a unique calibration solution. This study also confirmed that the solution becomes more robust if more than sufficient calibration references are provided. Practically, however, as more references are used, more inconsistencies can arise among the measured data for representing the biodynamic properties. To help account for the relative reliabilities of the references, a baseline weighting scheme is proposed. The analyses suggest that the best choice of calibration method depends on the modeling purpose, the model structure, and the availability and reliability of representative reference data. PMID:26740726

  1. Experimental verification of a theoretical model of an active cladding optical fiber fluorosensor

    NASA Technical Reports Server (NTRS)

    Albin, Sacharia; Briant, Alvin L.; Egalon, Claudio O.; Rogowski, Robert S.; Nankung, Juock S.

    1993-01-01

    Experiments were conducted to verify a theoretical model on the injection efficiency of sources in the cladding of an optical fiber. The theoretical results predicted an increase in the injection efficiency for higher differences in refractive indices between the core and cladding. The experimental apparatus used consisted of a glass rod 50 cm long, coated at one end with a thin film of fluorescent substance. The fluorescent substance was excited with side illumination, perpendicular to the rod axis, using a 476 nm Argon-ion laser. Part of the excited fluorescence was injected into the core and guided to a detector. The signal was measured for several different cladding refractive indices. The cladding consisted of sugar dissolved in water and the refractive index was changed by varying the sugar concentration in the solution. The results indicate that the power injected into the rod, due to evanescent wave injection, increases with the difference in refractive index which is in qualitative agreement with theory.

  2. Theoretical model and optimization of a novel temperature sensor based on quartz tuning fork resonators

    NASA Astrophysics Data System (ADS)

    Jun, Xu; Bo, You; Xin, Li; Juan, Cui

    2007-12-01

    To accurately measure temperatures, a novel temperature sensor based on a quartz tuning fork resonator has been designed. The principle of the quartz tuning fork temperature sensor is that the resonant frequency of the quartz resonator changes with the variation in temperature. This type of tuning fork resonator has been designed with a new doubly rotated cut work at flexural vibration mode as temperature sensor. The characteristics of the temperature sensor were evaluated and the results sufficiently met the target of development for temperature sensor. The theoretical model for temperature sensing has been developed and built. The sensor structure was analysed by finite element method (FEM) and optimized, including tuning fork geometry, tine electrode pattern and the sensor's elements size. The performance curve of output versus measured temperature is given. The results from theoretical analysis and experiments indicate that the sensor's sensitivity can reach 60 ppm °C-1 with the measured temperature range varying from 0 to 100 °C.

  3. High density monolayers of plasmid protein on latex particles: experiments and theoretical modeling

    NASA Astrophysics Data System (ADS)

    Kujda, Marta; Adamczyk, Zbigniew; Cieśla, Michał; Adamczyk, Małgorzata

    2015-04-01

    Monolayers obtained by adsorption of the plasmid protein KfrA on negatively charged polystyrene latex particles under diffusion-controlled conditions at pH 3.5 were interpreted in terms of the random sequential adsorption (RSA) model. A quantitative agreement of the theoretical results derived from these calculations with experimental data was attained for the ionic strength from 0.15 up to 10-2 M. This confirmed the adsorption mechanism of KfrA molecules on latex in the form of tetramers up to 10-2 M. On the other hand, for the ionic strength of 10-3 M the experimental coverage agreed with theoretical predictions under the assumption that screening of electrostatic interaction is enhanced by the presence of counterions and negatively charged polymer chains stemming from latex particles.

  4. Propagation predictions and studies using a ray tracing program combined with a theoretical ionospheric model

    NASA Technical Reports Server (NTRS)

    Lee, M. K.; Nisbet, J. S.

    1975-01-01

    Radio wave propagation predictions are described in which modern comprehensive theoretical ionospheric models are coupled with ray-tracing programs. In the computer code described, a network of electron density and collision frequency parameters along a band about the great circle path is calculated by specifying the transmitter and receiver geographic coordinates, time, the day number, and the 2800-MHz solar flux. The ray paths are calculated on specifying the frequency, mode, range of elevation angles, and range of azimuth angles from the great circle direction. The current program uses a combination of the Penn State MKI E and F region models and the Mitra-Rowe D and E region model. Application of the technique to the prediction of satellite to ground propagation and calculation of oblique incidence propagation paths and absorption are described. The implications of the study to the development of the next generation of ionospheric models are discussed.

  5. A Thematic Analysis of Theoretical Models for Translational Science in Nursing: Mapping the Field

    PubMed Central

    Mitchell, Sandra A.; Fisher, Cheryl A.; Hastings, Clare E.; Silverman, Leanne B.; Wallen, Gwenyth R.

    2010-01-01

    Background The quantity and diversity of conceptual models in translational science may complicate rather than advance the use of theory. Purpose This paper offers a comparative thematic analysis of the models available to inform knowledge development, transfer, and utilization. Method Literature searches identified 47 models for knowledge translation. Four thematic areas emerged: (1) evidence-based practice and knowledge transformation processes; (2) strategic change to promote adoption of new knowledge; (3) knowledge exchange and synthesis for application and inquiry; (4) designing and interpreting dissemination research. Discussion This analysis distinguishes the contributions made by leaders and researchers at each phase in the process of discovery, development, and service delivery. It also informs the selection of models to guide activities in knowledge translation. Conclusions A flexible theoretical stance is essential to simultaneously develop new knowledge and accelerate the translation of that knowledge into practice behaviors and programs of care that support optimal patient outcomes. PMID:21074646

  6. Absorption of Fast Waves at Moderate to High Ion Cyclotron Harmonics: Experimental Results and Theoretical Models

    NASA Astrophysics Data System (ADS)

    Pinsker, R. I.; Choi, M.; Prater, R.; Heidbrink, W. W.; Luo, Y.; Baity, F. W.; Murakami, M.; Porkolab, M.

    2006-10-01

    Strong absorption of fast Alfvén waves (FW) by ion cyclotron damping has been observed in DIII-D at the 4th and 5th harmonic of an injected beam while only weak absorption is observed at the 8th harmonic. The experimental results are compared with three different theoretical models; differences between the predictions of the models suggest the possible importance of finite-width orbit effects at high harmonics. In a linear model, it is found that damping on fast ions from neutral beam injection can be significant even at the 8th harmonic under experimentally relevant conditions. This is tested in experiments in DIII-D with FW power at 60 MHz and at 116 MHz. A novel Dα charge exchange recombination diagnostic is used to observe interaction of the FW power with beam ions. The results are compared with modeling with quasilinear and with orbit-following codes.

  7. Constraints on field theoretical models for variation of the fine structure constant

    NASA Astrophysics Data System (ADS)

    Steinhardt, Charles L.

    2005-02-01

    Recent theoretical ideas and observational claims suggest that the fine structure constant α may be variable. We examine a spectrum of models in which α is a function of a scalar field. Specifically, we consider three scenarios: oscillating α, monotonic time variation of α, and time-independent α that is spatially varying. We examine the constraints imposed upon these theories by cosmological observations, particle detector experiments, and “fifth force” experiments. These constraints are very strong on models involving oscillation but cannot compete with bounds from the Oklo subnuclear reactor on models with monotonic timelike variation of α. One particular model with spatial variation is consistent with all current experimental and observational measurements, including those from two seemingly conflicting measurements of the fine structure constant using the many multiplet method on absorption lines.

  8. Bridging the gap between theoretical ecology and real ecosystems: modeling invertebrate community composition in streams.

    PubMed

    Schuwirth, Nele; Reichert, Peter

    2013-02-01

    For the first time, we combine concepts of theoretical food web modeling, the metabolic theory of ecology, and ecological stoichiometry with the use of functional trait databases to predict the coexistence of invertebrate taxa in streams. We developed a mechanistic model that describes growth, death, and respiration of different taxa dependent on various environmental influence factors to estimate survival or extinction. Parameter and input uncertainty is propagated to model results. Such a model is needed to test our current quantitative understanding of ecosystem structure and function and to predict effects of anthropogenic impacts and restoration efforts. The model was tested using macroinvertebrate monitoring data from a catchment of the Swiss Plateau. Even without fitting model parameters, the model is able to represent key patterns of the coexistence structure of invertebrates at sites varying in external conditions (litter input, shading, water quality). This confirms the suitability of the model concept. More comprehensive testing and resulting model adaptations will further increase the predictive accuracy of the model.

  9. Theoretical Hill-Type Muscle and Stability: Numerical Model and Application

    PubMed Central

    Schmitt, S.; Günther, M.; Rupp, T.; Bayer, A.; Häufle, D.

    2013-01-01

    The construction of artificial muscles is one of the most challenging developments in today's biomedical science. The application of artificial muscles is focused both on the construction of orthotics and prosthetics for rehabilitation and prevention purposes and on building humanoid walking machines for robotics research. Research in biomechanics tries to explain the functioning and design of real biological muscles and therefore lays the fundament for the development of functional artificial muscles. Recently, the hyperbolic Hill-type force-velocity relation was derived from simple mechanical components. In this contribution, this theoretical yet biomechanical model is transferred to a numerical model and applied for presenting a proof-of-concept of a functional artificial muscle. Additionally, this validated theoretical model is used to determine force-velocity relations of different animal species that are based on the literature data from biological experiments. Moreover, it is shown that an antagonistic muscle actuator can help in stabilising a single inverted pendulum model in favour of a control approach using a linear torque generator. PMID:24319495

  10. A comprehensive theoretical model for on-chip microring-based photonic fractional differentiators

    PubMed Central

    Jin, Boyuan; Yuan, Jinhui; Wang, Kuiru; Sang, Xinzhu; Yan, Binbin; Wu, Qiang; Li, Feng; Zhou, Xian; Zhou, Guiyao; Yu, Chongxiu; Lu, Chao; Yaw Tam, Hwa; Wai, P. K. A.

    2015-01-01

    Microring-based photonic fractional differentiators play an important role in the on-chip all-optical signal processing. Unfortunately, the previous works do not consider the time-reversal and the time delay characteristics of the microring-based fractional differentiator. They also do not include the effect of input pulse width on the output. In particular, it cannot explain why the microring-based differentiator with the differentiation order n > 1 has larger output deviation than that with n < 1, and why the microring-based differentiator cannot reproduce the three-peak output waveform of an ideal differentiator with n > 1. In this paper, a comprehensive theoretical model is proposed. The critically-coupled microring resonator is modeled as an ideal first-order differentiator, while the under-coupled and over-coupled resonators are modeled as the time-reversed ideal fractional differentiators. Traditionally, the over-coupled microring resonators are used to form the differentiators with 1 < n < 2. However, we demonstrate that smaller fitting error can be obtained if the over-coupled microring resonator is fitted by an ideal differentiator with n < 1. The time delay of the differentiator is also considered. Finally, the influences of some key factors on the output waveform and deviation are discussed. The proposed theoretical model is beneficial for the design and application of the microring-based fractional differentiators. PMID:26381934

  11. Resource holding potential, subjective resource value, and game theoretical models of aggressiveness signalling.

    PubMed

    Hurd, Peter L

    2006-08-01

    Empirical evidence suggests that aggressiveness (willingness to enter into, or escalate an aggressive interaction) may be more important than the ability to win fights in some species. Both empirical and theoretical traditions treat aggressiveness as a distinct property from the ability (RHP) or motivation (subjective resource value) to win a fight. I examine how these three traits are clearly distinct when modelled using a simple strategic model of escalation. I then examine game theoretical models of agonistic communication and demonstrate that models in which aggressiveness is signalled require: (1) a trait, aggressiveness, which is neither a correlate, nor consequence of RHP or motivation, (2) a handicap which negates any benefit to be gained through the use of a particular signal, and (3) the absence of any other asymmetry which could be used to assign roles to players. I conclude that it is unlikely that these assumptions are ever met, and that empirical examples of "aggressiveness" are far more likely to represent long-term differences in subjective resource value.

  12. Theoretical Hill-type muscle and stability: numerical model and application.

    PubMed

    Schmitt, S; Günther, M; Rupp, T; Bayer, A; Häufle, D

    2013-01-01

    The construction of artificial muscles is one of the most challenging developments in today's biomedical science. The application of artificial muscles is focused both on the construction of orthotics and prosthetics for rehabilitation and prevention purposes and on building humanoid walking machines for robotics research. Research in biomechanics tries to explain the functioning and design of real biological muscles and therefore lays the fundament for the development of functional artificial muscles. Recently, the hyperbolic Hill-type force-velocity relation was derived from simple mechanical components. In this contribution, this theoretical yet biomechanical model is transferred to a numerical model and applied for presenting a proof-of-concept of a functional artificial muscle. Additionally, this validated theoretical model is used to determine force-velocity relations of different animal species that are based on the literature data from biological experiments. Moreover, it is shown that an antagonistic muscle actuator can help in stabilising a single inverted pendulum model in favour of a control approach using a linear torque generator. PMID:24319495

  13. 24 CFR 200.926c - Model code provisions for use in partially accepted code jurisdictions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 24 Housing and Urban Development 2 2012-04-01 2012-04-01 false Model code provisions for use in... Portions of the CABO One and Two Family Dwelling Code, 1992 Edition, including the 1993 amendments, with... Chapter 3. (e) Materials standards Chapter 26. (f) Construction components Part III. (g) Glass Chapter...

  14. Improving Technology Acceptance Modeling for Disadvantaged Communities Using a Systems Engineering Approach

    ERIC Educational Resources Information Center

    Fletcher, Jordan L.

    2013-01-01

    Developing nations are poised to spend billions on information and communication technology (ICT) innovation in 2020. A study of the historical adoption of ICT in developing nations has indicated that their adoption patterns do not follow typical technology innovation adoption models. This study addressed the weaknesses found in existing…

  15. Estimating Young's modulus of zona pellucida by micropipette aspiration in combination with theoretical models of ovum.

    PubMed

    Khalilian, Morteza; Navidbakhsh, Mahdi; Valojerdi, Mojtaba Rezazadeh; Chizari, Mahmoud; Yazdi, Poopak Eftekhari

    2010-04-01

    The zona pellucida (ZP) is the spherical layer that surrounds the mammalian oocyte. The physical hardness of this layer plays a crucial role in fertilization and is largely unknown because of the lack of appropriate measuring and modelling methods. The aim of this study is to measure the biomechanical properties of the ZP of human/mouse ovum and to test the hypothesis that Young's modulus of the ZP varies with fertilization. Young's moduli of ZP are determined before and after fertilization by using the micropipette aspiration technique, coupled with theoretical models of the oocyte as an elastic incompressible half-space (half-space model), an elastic compressible bilayer (layered model) or an elastic compressible shell (shell model). Comparison of the models shows that incorporation of the layered geometry of the ovum and the compressibility of the ZP in the layered and shell models may provide a means of more accurately characterizing ZP elasticity. Evaluation of results shows that although the results of the models are different, all confirm that the hardening of ZP will increase following fertilization. As can be seen, different choices of models and experimental parameters can affect the interpretation of experimental data and lead to differing mechanical properties.

  16. A Theoretical Model of Thermoelectric Transport Properties for Electrons and Phonons

    NASA Astrophysics Data System (ADS)

    Lee, HoSung

    2016-02-01

    A generic theoretical model for five bulk thermoelectric materials (PbTe, Bi2Te3, SnSe, Si0.7Ge0.3, and Mg2Si) has been developed based on the semiclassical model incorporating nonparabolicity, the two-band Kane model, the Hall factor, and the Debye-Callaway model for electrons and phonons. It is used to calculate thermoelectric transport properties, viz. the Seebeck coefficient, electrical conductivity, and electronic and lattice thermal conductivities, in the temperature range from room temperature up to 1200 K. The present model differs from others in the following regards: Firstly, thorough verification of modified electron scattering mechanisms is carried out by comparison with reported experimental data; Secondly, extensive verification of the model is presented, with concomitant agreement between calculations and reported measurements of effective masses, electron and hole concentrations, Seebeck coefficient, electrical conductivity, and electronic and lattice thermal conductivities; Thirdly, the present model provides the Fermi energy as a function of temperature and doping concentration; Fourthly, the velocities of sound are calculated using the Debye model rather than taken from literature. After verification of the present model, we were able to examine the recently attractive material SnSe, indicating a significant improvement in the dimensionless figure of merit.

  17. Parental modelling and prompting effects on acceptance of a novel fruit in 2-4-year-old children are dependent on children's food responsiveness.

    PubMed

    Blissett, Jackie; Bennett, Carmel; Fogel, Anna; Harris, Gillian; Higgs, Suzanne

    2016-02-14

    Few children consume the recommended portions of fruit or vegetables. This study examined the effects of parental physical prompting and parental modelling in children's acceptance of a novel fruit (NF) and examined the role of children's food-approach and food-avoidance traits on NF engagement and consumption. A total of 120 caregiver-child dyads (fifty-four girls, sixty-six boys) participated in this study. Dyads were allocated to one of the following three conditions: physical prompting but no modelling, physical prompting and modelling or a modelling only control condition. Dyads ate a standardised meal containing a portion of a fruit new to the child. Parents completed measures of children's food approach and avoidance. Willingness to try the NF was observed, and the amount of the NF consumed was measured. Physical prompting but no modelling resulted in greater physical refusal of the NF. There were main effects of enjoyment of food and food fussiness on acceptance. Food responsiveness interacted with condition such that children who were more food responsive had greater NF acceptance in the prompting and modelling conditions in comparison with the modelling only condition. In contrast, children with low food responsiveness had greater acceptance in the modelling control condition than in the prompting but no modelling condition. Physical prompting in the absence of modelling is likely to be detrimental to NF acceptance. Parental use of physical prompting strategies, in combination with modelling of NF intake, may facilitate acceptance of NF, but only in food-responsive children. Modelling consumption best promotes acceptance in children with low food responsiveness.

  18. A theoretical plate model accounting for slow kinetics in chromatographic elution.

    PubMed

    Baeza-Baeza, J J; García-Álvarez-Coque, M C

    2011-08-01

    The chromatographic elution has been studied from different perspectives. However, in spite of the simplicity and evident deficiencies of the plate model proposed by Martin and Synge, it has served as a basis for the characterization of columns up-to-date. This approach envisions the chromatographic column as an arbitrary number of theoretical plates, each of them consisting of identical repeating portions of mobile phase and stationary phase. Solutes partition between both phases, reaching the equilibrium. Mobile phase transference between the theoretical plates is assumed to be infinitesimally stepwise (or continuous), giving rise to the mixing of the solutions in adjacent plates. This yields an additional peak broadening, which is added to the dispersion associated to the equilibrium conditions. It is commonly assumed that when the solute concentration is sufficiently small, chromatographic elution is carried out under linear conditions, which is the case in almost all analytical applications. When the solute concentration increases above a value where the stationary phase approximates saturation (i.e. becomes overloaded), non-linear elution is obtained. In addition to overloading, another source of non-linearity can be a slow mass transfer. An extended Martin and Synge model is here proposed to include slow mass-transfer kinetics (with respect to flow rate) between the mobile phase and stationary phase. We show that there is a linear relationship between the variance and the ratio of the kinetic constants for the mass transfer in the flow direction (τ) and the mass transfer between the mobile phase and stationary phase (ν), which has been called the kinetic ratio (κ=τ/ν). The proposed model was validated with data obtained according to an approach that simulates the solute migration through the theoretical plates. An experimental approach to measure the deviation from the equilibrium conditions using the experimental peak variances and retention times at

  19. Inclusion of persistence length-based secondary structure in replica field theoretic models of heteropolymer freezing

    NASA Astrophysics Data System (ADS)

    Weber, Jeffrey K.; Pande, Vijay S.

    2013-09-01

    The protein folding problem has long represented a "holy grail" in statistical physics due to its physical complexity and its relevance to many human diseases. While past theoretical work has yielded apt descriptions of protein folding landscapes, recent large-scale simulations have provided insights into protein folding that were impractical to obtain from early theories. In particular, the role that non-native contacts play in protein folding, and their relation to the existence of misfolded, β-sheet rich trap states on folding landscapes, has emerged as a topic of interest in the field. In this paper, we present a modified model of heteropolymer freezing that includes explicit secondary structural characteristics which allow observations of "intramolecular amyloid" states to be probed from a theoretical perspective. We introduce a variable persistence length-based energy penalty to a model Hamiltonian, and we illustrate how this modification alters the phase transitions present in the theory. We find, in particular, that inclusion of this variable persistence length increases both generic freezing and folding temperatures in the model, allowing both folding and glass transitions to occur in a more highly optimized fashion. We go on to discuss how these changes might relate to protein evolution, misfolding, and the emergence of intramolecular amyloid states.

  20. Theoretical model for the evaporation loss of PM2.5 during filter sampling

    NASA Astrophysics Data System (ADS)

    Liu, Chun-Nan; Lin, Sih-Fan; Tsai, Chuen-Jinn; Wu, Yueh-Chuen; Chen, Chung-Fang

    2015-05-01

    The evaporation losses of PM2.5 particles in eight different size ranges corresponding to the 4th-10th stages and after filter of the MOUDI were calculated theoretically and then integrated to obtain the total PM2.5 evaporation loss. Results show that when PM2.5 particles are nearly neutral with pH in the range of 7-8, the evaporated concentrations predicted by the present model agree well with the experimental data with an average absolute difference of 20.2 ± 11.1%. When PM2.5 aerosols are acidic with pH less than 3.5, additional loss of nitrate and chloride can occur due to chemical interactions between collected particles and strong acids which are not considered in the present model. Under pH neutral conditions, the theoretical model was then used to examine the effect of PM2.5 concentration, gas-to-particle ratio, ambient temperature and relative humidity on the extent of evaporation loss. Results show that evaporated PM2.5 concentration increases with increasing temperature and decreasing relative humidity, PM2.5 concentration and gas-to-particle ratio.

  1. The nature of voids - I. Watershed void finders and their connection with theoretical models

    NASA Astrophysics Data System (ADS)

    Nadathur, S.; Hotchkiss, S.

    2015-12-01

    The statistical study of voids in the matter distribution promises to be an important tool for precision cosmology, but there are known discrepancies between theoretical models of voids and the voids actually found in large simulations or galaxy surveys. The empirical properties of observed voids are also not well understood. In this paper, we study voids in an N-body simulation, using the ZOBOV watershed algorithm. As in other studies, we use sets of subsampled dark matter particles as tracers to identify voids, but we use the full-resolution simulation output to measure dark matter densities at the identified locations. Voids span a wide range of sizes and densities, but there is a clear trend towards larger voids containing deeper density minima, a trend which is expected for all watershed void finders. We also find that the tracer density at void locations is usually smaller than the true density, and that this relationship depends on the sampling density of tracers. We show that fits given in the literature fail to match the observed density profiles of voids. The average enclosed density contrast within watershed voids varies widely with both the size of the void and the minimum density within it, but is always far from the shell-crossing threshold expected from theoretical models. Voids with deeper density minima also show much broader density profiles. We discuss the implications of these results for the excursion set approach to modelling such voids.

  2. A theoretical model of speed-dependent steering torque for rolling tyres

    NASA Astrophysics Data System (ADS)

    Wei, Yintao; Oertel, Christian; Liu, Yahui; Li, Xuebing

    2016-04-01

    It is well known that the tyre steering torque is highly dependent on the tyre rolling speed. In limited cases, i.e. parking manoeuvre, the steering torque approaches the maximum. With the increasing tyre speed, the steering torque decreased rapidly. Accurate modelling of the speed-dependent behaviour for the tyre steering torque is a key factor to calibrate the electric power steering (EPS) system and tune the handling performance of vehicles. However, no satisfactory theoretical model can be found in the existing literature to explain this phenomenon. This paper proposes a new theoretical framework to model this important tyre behaviour, which includes three key factors: (1) tyre three-dimensional transient rolling kinematics with turn-slip; (2) dynamical force and moment generation; and (3) the mixed Lagrange-Euler method for contact deformation solving. A nonlinear finite-element code has been developed to implement the proposed approach. It can be found that the main mechanism for the speed-dependent steering torque is due to turn-slip-related kinematics. This paper provides a theory to explain the complex mechanism of the tyre steering torque generation, which helps to understand the speed-dependent tyre steering torque, tyre road feeling and EPS calibration.

  3. The neural mediators of kindness-based meditation: a theoretical model

    PubMed Central

    Mascaro, Jennifer S.; Darcher, Alana; Negi, Lobsang T.; Raison, Charles L.

    2015-01-01

    Although kindness-based contemplative practices are increasingly employed by clinicians and cognitive researchers to enhance prosocial emotions, social cognitive skills, and well-being, and as a tool to understand the basic workings of the social mind, we lack a coherent theoretical model with which to test the mechanisms by which kindness-based meditation may alter the brain and body. Here, we link contemplative accounts of compassion and loving-kindness practices with research from social cognitive neuroscience and social psychology to generate predictions about how diverse practices may alter brain structure and function and related aspects of social cognition. Contingent on the nuances of the practice, kindness-based meditation may enhance the neural systems related to faster and more basic perceptual or motor simulation processes, simulation of another’s affective body state, slower and higher-level perspective-taking, modulatory processes such as emotion regulation and self/other discrimination, and combinations thereof. This theoretical model will be discussed alongside best practices for testing such a model and potential implications and applications of future work. PMID:25729374

  4. The neural mediators of kindness-based meditation: a theoretical model.

    PubMed

    Mascaro, Jennifer S; Darcher, Alana; Negi, Lobsang T; Raison, Charles L

    2015-01-01

    Although kindness-based contemplative practices are increasingly employed by clinicians and cognitive researchers to enhance prosocial emotions, social cognitive skills, and well-being, and as a tool to understand the basic workings of the social mind, we lack a coherent theoretical model with which to test the mechanisms by which kindness-based meditation may alter the brain and body. Here, we link contemplative accounts of compassion and loving-kindness practices with research from social cognitive neuroscience and social psychology to generate predictions about how diverse practices may alter brain structure and function and related aspects of social cognition. Contingent on the nuances of the practice, kindness-based meditation may enhance the neural systems related to faster and more basic perceptual or motor simulation processes, simulation of another's affective body state, slower and higher-level perspective-taking, modulatory processes such as emotion regulation and self/other discrimination, and combinations thereof. This theoretical model will be discussed alongside best practices for testing such a model and potential implications and applications of future work.

  5. Poroelastic behaviors of the osteon: A comparison of two theoretical osteon models

    NASA Astrophysics Data System (ADS)

    Wu, Xiao-Gang; Chen, Wei-Yi

    2013-08-01

    In the paper, two theoretical poroelastic osteon models are presented to compare their poroelastic behaviors, one is the hollow osteon model (Haversian fluid is neglected) and the other is the osteon model with Haversian fluid considered. They both have the same two types of impermeable exterior boundary conditions, one is elastic restraint and the other is displacement constrained, which can be used for analyzing other experiments performed on similarly shaped poroelastic specimens. The obtained analytical pressure and velocity solutions demonstrate the effects of the loading factors and the material parameters, which may have a significant stimulus to the mechanotransduction of bone remodeling signals. Model comparisons indicate: (1) The Haversian fluid can enhance the whole osteonal fluid pressure and velocity fields. (2) In the hollow model, the key loading factor governing the poroelastic behavior of the osteon is strain rate, while in the model with Haversian fluid considered, the strain rate governs only the velocity. (3) The pressure amplitude is proportional to the loading frequency in the hollow model, while in the model with Haversian fluid considered, the loading frequency has little effect on the pressure amplitude.

  6. Theoretical Model for the Formation of Caveolae and Similar Membrane Invaginations

    PubMed Central

    Sens, Pierre; Turner, Matthew S.

    2004-01-01

    We study a physical model for the formation of bud-like invaginations on fluid lipid membranes under tension, and apply this model to caveolae formation. We demonstrate that budding can be driven by membrane-bound proteins, provided that they exert asymmetric forces on the membrane that give rise to bending moments. In particular, caveolae formation does not necessarily require forces to be applied by the cytoskeleton. Our theoretical model is able to explain several features observed experimentally in caveolae, where proteins in the caveolin family are known to play a crucial role in the formation of caveolae buds. These include 1), the formation of caveolae buds with sizes in the 100-nm range and 2), that certain N- and C-termini deletion mutants result in vesicles that are an order-of-magnitude larger. Finally, we discuss the possible origin of the morphological striations that are observed on the surfaces of the caveolae. PMID:15041647

  7. Theoretical models of interstellar shocks. I - Radiative transfer and UV precursors

    NASA Technical Reports Server (NTRS)

    Shull, J. M.; Mckee, C. F.

    1979-01-01

    Theoretical models of interstellar radiative shocks are constructed, with special attention to the transfer of ionizing radiation. These models are 'self-consistent' in the sense that the emergent ionizing radiation (the UV precursor) is coupled with the ionization state of H, He, and the metals in the preshock gas. For shock velocities of at least 110 km/s the shocks generate sufficient UV radiation for complete preionization of H and He, the latter to He(+). At lower velocities the preionization can be much smaller, with important consequences for the cooling function, the shock structure, and the emission. For models with shock velocities of 40 to 130 km/s the intensities of the strongest emission lines in the UV, optical, and infrared are tabulated, as well as postshock column densities of metal ions potentially observable by UV absorption spectroscopy. Possible applications to supernova remnants and high-velocity interstellar gas are assessed.

  8. Inference of ICF implosion core mix using experimental data and theoretical mix modeling

    SciTech Connect

    Sherrill, Leslie Welser; Haynes, Donald A; Cooley, James H; Sherrill, Manolo E; Mancini, Roberto C; Tommasini, Riccardo; Golovkin, Igor E; Haan, Steven W

    2009-01-01

    The mixing between fuel and shell materials in Inertial Confinement Fusion (lCF) implosion cores is a current topic of interest. The goal of this work was to design direct-drive ICF experiments which have varying levels of mix, and subsequently to extract information on mixing directly from the experimental data using spectroscopic techniques. The experimental design was accomplished using hydrodynamic simulations in conjunction with Haan's saturation model, which was used to predict the mix levels of candidate experimental configurations. These theoretical predictions were then compared to the mixing information which was extracted from the experimental data, and it was found that Haan's mix model predicted trends in the width of the mix layer as a function of initial shell thickness. These results contribute to an assessment of the range of validity and predictive capability of the Haan saturation model, as well as increasing confidence in the methods used to extract mixing information from experimental data.

  9. B → K∗ ℓ + ℓ - decays at large recoil in the Standard Model: a theoretical reappraisal

    NASA Astrophysics Data System (ADS)

    Ciuchini, Marco; Fedele, Marco; Franco, Enrico; Mishima, Satoshi; Paul, Ayan; Silvestrini, Luca; Valli, Mauro

    2016-06-01

    We critically reassess the theoretical uncertainties in the Standard Model calculation of the B → K ∗ ℓ + ℓ - observables, focusing on the low q 2 region. We point out that even optimized observables are affected by sizable uncertainties, since hadronic contributions generated by current-current operators with charm are difficult to estimate, especially for q 2 ˜ 4 m c 2 ≃ 6.8 GeV2. We perform a detailed numerical analysis and present both predictions and results from the fit obtained using most recent data. We find that non-factorizable power corrections of the expected order of magnitude are sufficient to give a good description of current experimental data within the Standard Model. We discuss in detail the q 2 dependence of the corrections and their possible interpretation as shifts of the Standard Model Wilson coefficients.

  10. The calculation of theoretical chromospheric models and the interpretation of solar spectra from rockets and spacecraft

    NASA Technical Reports Server (NTRS)

    Avrett, E. H.

    1984-01-01

    Models and spectra of sunspots were studied, because they are important to energy balance and variability discussions. Sunspot observations in the ultraviolet region 140 to 168 nn was obtained by the NRL High Resolution Telescope and Spectrograph. Extensive photometric observations of sunspot umbrae and prenumbrae in 10 chanels covering the wavelength region 387 to 3800 nm were made. Cool star opacities and model atmospheres were computed. The Sun is the first testcase, both to check the opacity calculations against the observed solar spectrum, and to check the purely theoretical model calculation against the observed solar energy distribution. Line lists were finally completed for all the molecules that are important in computing statistical opacities for energy balance and for radiative rate calculations in the Sun (except perhaps for sunspots). Because many of these bands are incompletely analyzed in the laboratory, the energy levels are not well enough known to predict wavelengths accurately for spectrum synthesis and for detailed comparison with the observations.

  11. Theoretical shell-model signatures in heavy-ion, coherent pion production

    NASA Technical Reports Server (NTRS)

    Maung, Khin M.; Deutchman, P. A.; Buvel, R. L.

    1992-01-01

    A comprehensive summary of a many-body, microscopic, particle-hole formalism is presented that describes coherent, subthreshold, pion production in peripheral, heavy-ion collisions. The formalism uses a new separable model transition interaction that produces Delta-hole states in either the projectile or target nucleus. Shell-model states described by harmonic oscillator functions are used in the calculation of Delta formation and decay and Lorentz-contraction effects of the nucleus not at rest are included. An analytical expression to lowest multipole order for the differential cross section is examined. The sensitivity of the theoretical results to the shell-model states is determined with preliminary shape results compared with data. The effects of higher multipoles are examined with attention paid to the second-order multipole value.

  12. Theoretical analysis of electronic absorption spectra of vitamin B12 models

    NASA Astrophysics Data System (ADS)

    Andruniow, Tadeusz; Kozlowski, Pawel M.; Zgierski, Marek Z.

    2001-10-01

    Time-dependent density-functional theory (TD-DFT) is applied to analyze the electronic absorption spectra of vitamin B12. To accomplish this two model systems were considered: CN-[CoIII-corrin]-CN (dicyanocobinamide, DCC) and imidazole-[CoIII-corrin]-CN (cyanocobalamin, ImCC). For both models 30 lowest excited states were calculated together with transition dipole moments. When the results of TD-DFT calculations were directly compared with experiment it was found that the theoretical values systematically overestimate experimental data by approximately 0.5 eV. The uniform adjustment of the calculated transition energies allowed detailed analysis of electronic absorption spectra of vitamin B12 models. All absorption bands in spectral range 2.0-5.0 eV were readily assigned. In particular, TD-DFT calculations were able to explain the origin of the shift of the lowest absorption band caused by replacement of the-CN axial ligand by imidazole.

  13. (A whistle-stop tour of) theoretical models of diffraction in DIS

    SciTech Connect

    McDermott, M. F.

    1997-04-20

    The purpose of this talk was to present a very brief overview of theoretical models of diffraction in deep inelastic scattering (DIS). In particular, predictions for the behaviour of the diffractive structure functions F{sub 2}{sup D}, R{sup D} are presented. The measurement of these functions at both small and high values of the variable {beta} and their evolution with Q{sup 2} is expected to reveal crucial information concerning the underlying dynamics. This talk is based on the more extensive review which also discusses expectations for charm in diffraction and contains a more complete list of references.

  14. Multimode cavity QED 2: Parameter dependence and limitations through theoretical modeling

    NASA Astrophysics Data System (ADS)

    Groszkowski, Peter; Leung, Nelson; Naik, Ravi; Chakram, Srivatsan; Schuster, David; Koch, Jens

    Superconducting circuits are well-established as promising building blocks for future quantum information processing devices. While in recent years gate and readout fidelities have improved significantly, superconducting qubits can still benefit greatly from added intrinsic robustness and improved error resilience. In this talk, we present results for qubits based on the modes of a 1d resonator array, where qubit manipulation and readout are achieved by interaction with a parametrically driven superconducting transmon. Through theoretical modeling, we provide insight into mode addressability as well as crosstalk, and their dependence on the system's size in various parameter regimes.

  15. Hospital design and face-to-face interaction among clinicians: a theoretical model.

    PubMed

    Rashid, Mahbub

    2009-01-01

    A growing body of literature suggests that face-to-face interaction among clinicians in hospitals affects patient outcomes. How can face-to-face interaction among clinicians be influenced positively to improve patient outcomes in hospitals? So far, most strategies for improving face-to-face interaction in hospitals have focused on changing organizational culture. In contrast, this paper proposes a theoretical model that shows how spatial program and structure can help face-to-face interaction fulfill its purposes in hospitals by controlling the interfaces among different communities of clinicians. PMID:21165842

  16. Morphology of synthetic chrysoberyl and alexandrite crystals: Analysis of experimental data and theoretical modeling

    NASA Astrophysics Data System (ADS)

    Gromalova, N. A.; Eremin, N. N.; Dorokhova, G. I.; Urusov, V. S.

    2012-07-01

    A morphological analysis of chrysoberyl and alexandrite crystals obtained by flux crystallization has been performed. Seven morphological types of crystals are selected. The surface energies of the faces of chrysoberyl and alexandrite crystals and their isostructural analogs, BeCr2O4 and BeFe2O4, have been calculated by atomistic computer modeling using the Metadise program. A "combined" approach is proposed which takes into account both the structural geometry and the surface energy of the faces and thus provides better agreement between the theoretical and experimentally observed faceting of chrysoberyl and alexandrite crystals.

  17. Theoretical model study of dynamic ferromagnetic susceptibility in mono-layer graphene

    NASA Astrophysics Data System (ADS)

    Sahu, Sivabrata; Parashar, S. K. S.; Rout, G. C.

    2016-04-01

    We report here a microscopic theoretical study of dynamic ferromagnetic spin susceptibility of electrons for graphene systems, which deal with a tight-binding model Hamiltonian consisting of the hopping of electrons up to third-nearest-neighbors, impurity and substrate effects besides Coulomb interaction of electrons at A-and B- sub- lattices. The spin susceptibility involves four two-particle Green's functions, which are calculated by Zubarev's Green's function technique. The up and down electron occupancies at A and B sub-lattices are computed numerically and self-consistently. The temperature dependent susceptibility shows a pronounced peak at Curie temperature for critical Coulomb interaction Uc = 2.2t1.

  18. Microscopic theoretical model study of band gap opening in AA-stacked bi-layer graphene

    NASA Astrophysics Data System (ADS)

    Sahu, Sivabrata; Parashar, S. K. S.; Rout, G. C.

    2016-05-01

    We address here a tight-binding theoretical model calculation for AA-stacked bi-layer graphene taking into account of a biased potential between two layers to study the density of states and the band dispersion within the total Brillouin zone. We have calculated the electronic Green's function for electron operator corresponding to A and B sub lattices by Zubarev's Green's function technique from which the electronic density of states and the electron band energy dispersion are calculated. The numerically computed density of states and band energy dispersions are investigated by tuning the biased potential to exhibit the band gap by varying the different physical parameters.

  19. Information-theoretic model selection and model averaging for closed-population capture-recapture studies

    USGS Publications Warehouse

    Stanley, T.R.; Burnham, K.P.

    1998-01-01

    Specification of an appropriate model is critical to valid stalistical inference. Given the "true model" for the data is unknown, the goal of model selection is to select a plausible approximating model that balances model bias and sampling variance. Model selection based on information criteria such as AIC or its variant AICc, or criteria like CAIC, has proven useful in a variety of contexts including the analysis of open-population capture-recapture data. These criteria have not been intensively evaluated for closed-population capture-recapture models, which are integer parameter models used to estimate population size (N), and there is concern that they will not perform well. To address this concern, we evaluated AIC, AICc, and CAIC model selection for closed-population capture-recapture models by empirically assessing the quality of inference for the population size parameter N. We found that AIC-, AICc-, and CAIC-selected models had smaller relative mean squared errors than randomly selected models, but that confidence interval coverage on N was poor unless unconditional variance estimates (which incorporate model uncertainty) were used to compute confidence intervals. Overall, AIC and AICc outperformed CAIC, and are preferred to CAIC for selection among the closed-population capture-recapture models we investigated. A model averaging approach to estimation, using AIC. AICc, or CAIC to estimate weights, was also investigated and proved superior to estimation using AIC-, AICc-, or CAIC-selected models. Our results suggested that, for model averaging, AIC or AICc. should be favored over CAIC for estimating weights.

  20. Reliability and acceptability of a five-station multiple mini-interview model for residency program recruitment

    PubMed Central

    Fraga, Julian Diaz; Oluwasanjo, Adetokunbo; Wasser, Thomas; Donato, Anthony; Alweis, Richard

    2013-01-01

    Background Standard interviews are used by most residency programs in the United States for assessment of aptitude of the non-cognitive competencies, but variability of interviewer skill, interviewer bias, interviewer leniency or stringency, and context specificity limit reliability. Aim To investigate reliability and acceptability of five-station multiple mini-interview (MMI) model for resident selection into an internal medicine residency program in the United States. Setting One independent academic medical center. Participants Two hundred and thirty-seven applicants and 17 faculty interviewers. Program description Five, 10-min MMI stations with five different interviewers blinded to the candidate's records and one traditional 20-min interview with the program director. Candidates were rated on two items: interpersonal and communication skills, and overall performance. Program evaluation Generalizability data showed that the reliability of our process was high (>0.9). The results of anonymous surveys demonstrated that both applicants and interviewers consider the MMI as a fair and more effective tool to evaluate non-cognitive traits, and prefer the MMI to standard interviews. Discussion The MMI process for residency interviews can generate reliable interview results using only five stations, and it is acceptable and preferred over standard interview modalities by the applicants and faculty members of one US residency program. PMID:24392211

  1. Regulatory acceptance and use of 3R models for pharmaceuticals and chemicals: expert opinions on the state of affairs and the way forward.

    PubMed

    Schiffelers, Marie-Jeanne W A; Blaauboer, Bas J; Bakker, Wieger E; Beken, Sonja; Hendriksen, Coenraad F M; Koëter, Herman B W M; Krul, Cyrille

    2014-06-01

    Pharmaceuticals and chemicals are subjected to regulatory safety testing accounting for approximately 25% of laboratory animal use in Europe. This testing meets various objections and has led to the development of a range of 3R models to Replace, Reduce or Refine the animal models. However, these models must overcome many barriers before being accepted for regulatory risk management purposes. This paper describes the barriers and drivers and options to optimize this acceptance process as identified by two expert panels, one on pharmaceuticals and one on chemicals. To untangle the complex acceptance process, the multilevel perspective on technology transitions is applied. This perspective defines influences at the micro-, meso- and macro level which need alignment to induce regulatory acceptance of a 3R model. This paper displays that there are many similar mechanisms within both sectors that prevent 3R models from becoming accepted for regulatory risk assessment and management. Shared barriers include the uncertainty about the value of the new 3R models (micro level), the lack of harmonization of regulatory requirements and acceptance criteria (meso level) and the high levels of risk aversion (macro level). In optimizing the process commitment, communication, cooperation and coordination are identified as critical drivers.

  2. Game Theoretic Modeling of Water Resources Allocation Under Hydro-Climatic Uncertainty

    NASA Astrophysics Data System (ADS)

    Brown, C.; Lall, U.; Siegfried, T.

    2005-12-01

    Typical hydrologic and economic modeling approaches rely on assumptions of climate stationarity and economic conditions of ideal markets and rational decision-makers. In this study, we incorporate hydroclimatic variability with a game theoretic approach to simulate and evaluate common water allocation paradigms. Game Theory may be particularly appropriate for modeling water allocation decisions. First, a game theoretic approach allows economic analysis in situations where price theory doesn't apply, which is typically the case in water resources where markets are thin, players are few, and rules of exchange are highly constrained by legal or cultural traditions. Previous studies confirm that game theory is applicable to water resources decision problems, yet applications and modeling based on these principles is only rarely observed in the literature. Second, there are numerous existing theoretical and empirical studies of specific games and human behavior that may be applied in the development of predictive water allocation models. With this framework, one can evaluate alternative orderings and rules regarding the fraction of available water that one is allowed to appropriate. Specific attributes of the players involved in water resources management complicate the determination of solutions to game theory models. While an analytical approach will be useful for providing general insights, the variety of preference structures of individual players in a realistic water scenario will likely require a simulation approach. We propose a simulation approach incorporating the rationality, self-interest and equilibrium concepts of game theory with an agent-based modeling framework that allows the distinct properties of each player to be expressed and allows the performance of the system to manifest the integrative effect of these factors. Underlying this framework, we apply a realistic representation of spatio-temporal hydrologic variability and incorporate the impact of

  3. Toward a Theoretical Model of Decision-Making and Resistance to Change among Higher Education Online Course Designers

    ERIC Educational Resources Information Center

    Dodd, Bucky J.

    2013-01-01

    Online course design is an emerging practice in higher education, yet few theoretical models currently exist to explain or predict how the diffusion of innovations occurs in this space. This study used a descriptive, quantitative survey research design to examine theoretical relationships between decision-making style and resistance to change…

  4. Exercise motives and positive body image in physically active college women and men: Exploring an expanded acceptance model of intuitive eating.

    PubMed

    Tylka, Tracy L; Homan, Kristin J

    2015-09-01

    The acceptance model of intuitive eating posits that body acceptance by others facilitates body appreciation and internal body orientation, which contribute to intuitive eating. Two domains of exercise motives (functional and appearance) may also be linked to these variables, and thus were integrated into the model. The model fit the data well for 406 physically active U.S. college students, although some pathways were stronger for women. Body acceptance by others directly contributed to higher functional exercise motives and indirectly contributed to lower appearance exercise motives through higher internal body orientation. Functional exercise motives positively, and appearance exercise motives inversely, contributed to body appreciation. Whereas body appreciation positively, and appearance exercise motives inversely, contributed to intuitive eating for women, only the latter association was evident for men. To benefit positive body image and intuitive eating, efforts should encourage body acceptance by others and emphasize functional and de-emphasize appearance exercise motives. PMID:26281958

  5. Experimental observation, theoretical models, and biomechanical inference in the study of mandibular form.

    PubMed

    Daegling, D J; Hylander, W L

    2000-08-01

    Experimental studies and mathematical models are disparate approaches for inferring the stress and strain environment in mammalian jaws. Experimental designs offer accurate, although limited, characterization of biomechanical behavior, while mathematical approaches (finite element modeling in particular) offer unparalleled precision in depiction of strain magnitudes, directions, and gradients throughout the mandible. Because the empirical (experimental) and theoretical (mathematical) perspectives differ in their initial assumptions and their proximate goals, the two methods can yield divergent conclusions about how masticatory stresses are distributed in the dentary. These different sources of inference may, therefore, tangibly influence subsequent biological interpretation. In vitro observation of bone strain in primate mandibles under controlled loading conditions offers a test of finite element model predictions. Two issues which have been addressed by both finite element models and experimental approaches are: (1) the distribution of torsional shear strains in anthropoid jaws and (2) the dissipation of bite forces in the human alveolar process. Not surprisingly, the experimental data and mathematical models agree on some issues, but on others exhibit discordance. Achieving congruence between these methods is critical if the nature of the relationship of masticatory stress to mandibular form is to be intelligently assessed. A case study of functional/mechanical significance of gnathic morphology in the hominid genus Paranthropus offers insight into the potential benefit of combining theoretical and experimental approaches. Certain finite element analyses claim to have identified a biomechanical problem unrecognized in previous comparative work, which, in essence, is that the enlarged transverse dimensions of the postcanine corpus may have a less important role in resisting torsional stresses than previously thought. Experimental data have identified

  6. Experimental observation, theoretical models, and biomechanical inference in the study of mandibular form.

    PubMed

    Daegling, D J; Hylander, W L

    2000-08-01

    Experimental studies and mathematical models are disparate approaches for inferring the stress and strain environment in mammalian jaws. Experimental designs offer accurate, although limited, characterization of biomechanical behavior, while mathematical approaches (finite element modeling in particular) offer unparalleled precision in depiction of strain magnitudes, directions, and gradients throughout the mandible. Because the empirical (experimental) and theoretical (mathematical) perspectives differ in their initial assumptions and their proximate goals, the two methods can yield divergent conclusions about how masticatory stresses are distributed in the dentary. These different sources of inference may, therefore, tangibly influence subsequent biological interpretation. In vitro observation of bone strain in primate mandibles under controlled loading conditions offers a test of finite element model predictions. Two issues which have been addressed by both finite element models and experimental approaches are: (1) the distribution of torsional shear strains in anthropoid jaws and (2) the dissipation of bite forces in the human alveolar process. Not surprisingly, the experimental data and mathematical models agree on some issues, but on others exhibit discordance. Achieving congruence between these methods is critical if the nature of the relationship of masticatory stress to mandibular form is to be intelligently assessed. A case study of functional/mechanical significance of gnathic morphology in the hominid genus Paranthropus offers insight into the potential benefit of combining theoretical and experimental approaches. Certain finite element analyses claim to have identified a biomechanical problem unrecognized in previous comparative work, which, in essence, is that the enlarged transverse dimensions of the postcanine corpus may have a less important role in resisting torsional stresses than previously thought. Experimental data have identified

  7. Prefission Constriction of Golgi Tubular Carriers Driven by Local Lipid Metabolism: A Theoretical Model

    PubMed Central

    Shemesh, Tom; Luini, Alberto; Malhotra, Vivek; Burger, Koert N. J.; Kozlov, Michael M.

    2003-01-01

    Membrane transport within mammalian cells is mediated by small vesicular as well as large pleiomorphic transport carriers (TCs). A major step in the formation of TCs is the creation and subsequent narrowing of a membrane neck connecting the emerging carrier with the initial membrane. In the case of small vesicular TCs, neck formation may be directly induced by the coat proteins that cover the emerging vesicle. However, the mechanism underlying the creation and narrowing of a membrane neck in the generation of large TCs remains unknown. We present a theoretical model for neck formation based on the elastic model of membranes. Our calculations suggest a lipid-driven mechanism with a central role for diacylglycerol (DAG). The model is applied to a well-characterized in vitro system that reconstitutes TC formation from the Golgi complex, namely the pearling and fission of Golgi tubules induced by CtBP/BARS, a protein that catalyzes the conversion of lysophosphatidic acid into phosphatidic acid. In view of the importance of a PA-DAG cycle in the formation of Golgi TCs, we assume that the newly formed phosphatidic acid undergoes rapid dephosphorylation into DAG. DAG possesses a unique molecular shape characterized by an extremely large negative spontaneous curvature, and it redistributes rapidly between the membrane monolayers and along the membrane surface. Coupling between local membrane curvature and local lipid composition results, by mutual enhancement, in constrictions of the tubule into membrane necks, and a related inhomogeneous lateral partitioning of DAG. Our theoretical model predicts the exact dimensions of the constrictions observed in the pearling Golgi tubules. Moreover, the model is able to explain membrane neck formation by physiologically relevant mole fractions of DAG. PMID:14645071

  8. 3D-manufactured patient-specific models of congenital heart defects for communication in clinical practice: feasibility and acceptability

    PubMed Central

    Biglino, Giovanni; Capelli, Claudio; Wray, Jo; Schievano, Silvia; Leaver, Lindsay-Kay; Khambadkone, Sachin; Giardini, Alessandro; Derrick, Graham; Jones, Alexander; Taylor, Andrew M

    2015-01-01

    Objectives To assess the communication potential of three-dimensional (3D) patient-specific models of congenital heart defects and their acceptability in clinical practice for cardiology consultations. Design This was a questionnaire-based study in which participants were randomised into two groups: the ‘model group’ received a 3D model of the cardiac lesion(s) being discussed during their appointment, while the ‘control group’ had a routine visit. Setting Outpatient clinic, cardiology follow-up visits. Participants 103 parents of children with congenital heart disease were recruited (parental age: 43±8 years; patient age: 12±6 years). In order to have a 3D model made, patients needed to have a recent cardiac MRI examination; this was the crucial inclusion criterion. Interventions Questionnaires were administered to the participants before and after the visits and an additional questionnaire was administered to the attending cardiologist. Main outcome measures Rating (1–10) for the liking of the 3D model, its usefulness and the clarity of the explanation received were recorded, as well as rating (1–10) of the parental understanding and their engagement according to the cardiologist. Furthermore, parental knowledge was assessed by asking them to mark diagrams, tick keywords and provide free text answers. The duration of consultations was recorded and parent feedback collected. Results Parents and cardiologists both found the models to be very useful and helpful in engaging the parents in discussing congenital heart defects. Parental knowledge was not associated with their level of education (p=0.2) and did not improve following their visit. Consultations involving 3D models lasted on average 5 min longer (p=0.02). Conclusions Patient-specific models can enhance engagement with parents and improve communication between cardiologists and parents, potentially impacting on parent and patient psychological adjustment following treatment. However, in

  9. Theoretical study on the inverse modeling of deep body temperature measurement.

    PubMed

    Huang, Ming; Chen, Wenxi

    2012-03-01

    We evaluated the theoretical aspects of monitoring the deep body temperature distribution with the inverse modeling method. A two-dimensional model was built based on anatomical structure to simulate the human abdomen. By integrating biophysical and physiological information, the deep body temperature distribution was estimated from cutaneous surface temperature measurements using an inverse quasilinear method. Simulations were conducted with and without the heat effect of blood perfusion in the muscle and skin layers. The results of the simulations showed consistently that the noise characteristics and arrangement of the temperature sensors were the major factors affecting the accuracy of the inverse solution. With temperature sensors of 0.05 °C systematic error and an optimized 16-sensor arrangement, the inverse method could estimate the deep body temperature distribution with an average absolute error of less than 0.20 °C. The results of this theoretical study suggest that it is possible to reconstruct the deep body temperature distribution with the inverse method and that this approach merits further investigation.

  10. Ultraviolet Properties of Primeval Galaxies: Theoretical Models from Stellar Population Synthesis

    NASA Astrophysics Data System (ADS)

    Buzzoni, Alberto

    2002-03-01

    The ultraviolet luminosity evolution of star-forming galaxies is explored from the theoretical point of view, especially focusing on the theory of UV energetics in simple and composite stellar populations and its relationship to the star formation rate and other main evolutionary parameters. Galaxy emission below λ<3000 Å directly correlates with actual star formation, not depending on the total mass of the system. A straightforward calibration is obtained, in this sense, from the theoretical models at 1600, 2000, and 2800 Å, and a full comparison is carried out with IUE data and other balloon-borne observations for local galaxies. The claimed role of late-type systems as prevailing contributors to the cosmic UV background is reinforced by our results; at 2000 Å, Im irregulars are found in fact nearly 4 orders of magnitude brighter than ellipticals, per unit luminous mass. The role of dust absorption in the observation of high-redshift galaxies is assessed, comparing the model output and observed spectral energy distribution of local galaxy samples. Similar to what we observe in our own galaxy, a quick evolution in the dust environment might be envisaged in primeval galaxies, with an increasing fraction of luminous matter that would escape the regions of harder and ``clumpy'' dust absorption on a timescale of some 107 yr, comparable to the lifetime of stars of 5-10 Msolar.

  11. Theoretical study of haemoperfusion: drugs obeying a one-compartment pharmacokinetics model.

    PubMed

    Guenzet, J; Bourin, M; Laurent, D; Aminou, T

    1985-05-01

    A general theory of haemoperfusion for drugs obeying the one-compartment pharmacokinetics model is proposed. The following theoretical cases are investigated: First case Adsorption and desorption are first-order reactions without biotransformation, and elimination rate is first-order. Two particular cases are examined: no desorption and alpha = beta. Second case: Adsorption and desorption rates are first-order, without biotransformation, and elimination rate is zero-order. Third case: Adsorption rate is first-order and desorption rate is zero-order, without biotransformation, and elimination is either first-order or zero-order. Fourth case Adsorption rate is zero-order and desorption rate is first-order, without biotransformation, and elimination is either first-order or zero-order. Fifth case: Adsorption and desorption rates are first-order, with biotransformation. In all these pharmacokinetics models for haemoperfusion, theoretical computations lead to the values of adsorbed amount and plasma level, in relation to time. Clearances are also computed. In most cases, haemoperfusion must be performed quickly because of the desorption phenomenon. Parameters modulating the adsorption process are: surface area, blood flow, drug concentration in blood, adsorbent nature and adsorbent quantity.

  12. Theoretical modeling for radiofrequency ablation: state-of-the-art and challenges for the future

    PubMed Central

    Berjano, Enrique J

    2006-01-01

    Radiofrequency ablation is an interventional technique that in recent years has come to be employed in very different medical fields, such as the elimination of cardiac arrhythmias or the destruction of tumors in different locations. In order to investigate and develop new techniques, and also to improve those currently employed, theoretical models and computer simulations are a powerful tool since they provide vital information on the electrical and thermal behavior of ablation rapidly and at low cost. In the future they could even help to plan individual treatment for each patient. This review analyzes the state-of-the-art in theoretical modeling as applied to the study of radiofrequency ablation techniques. Firstly, it describes the most important issues involved in this methodology, including the experimental validation. Secondly, it points out the present limitations, especially those related to the lack of an accurate characterization of the biological tissues. After analyzing the current and future benefits of this technique it finally suggests future lines and trends in the research of this area. PMID:16620380

  13. A theoretical analysis model of realizing wavelength converter based on saturable absorber

    NASA Astrophysics Data System (ADS)

    Zhao, Tonggang; Ren, Jianhua; Zhao, Ronghua; Wang, Lili; Rao, Lan; Lin, Jintong

    2005-02-01

    As the key apparatus, the All optical Wavelength Converter (AOWC) will play an important role in future optical communication and optical signal processing system. In this paper, switching characteristics of wavelength converter based on saturable absorber in semiconductor lasers will be researched. This kind of conversion mechanism possesses some advantage, such as simple structure, low cost, high stability and so on. This paper is organized as follows: Firstly, utilizing rate equations, a new theoretical model on wavelength conversion based on saturable absorber is put forward. Nextly, the frequency modulation response of wavelength conversion will be discussed under the small-signal analysis based on the theoretical model. Lastly, Numerical value solution results will be given out when external signal light injects in saturable absorber region of semiconductor lasers. The characteristics of wavelength conversion are simulated in different optical parameters including the injection current, the input signal optical power and bit rate. Those results are useful to realization and the optimal design of the wavelength converter based on saturable absorber.

  14. Transport of fluorobenzoate tracers in a vegetated hydrologic control volume: 2. Theoretical inferences and modeling

    NASA Astrophysics Data System (ADS)

    Queloz, Pierre; Carraro, Luca; Benettin, Paolo; Botter, Gianluca; Rinaldo, Andrea; Bertuzzo, Enrico

    2015-04-01

    A theoretical analysis of transport in a controlled hydrologic volume, inclusive of two willow trees and forced by erratic water inputs, is carried out contrasting the experimental data described in a companion paper. The data refer to the hydrologic transport in a large lysimeter of different fluorobenzoic acids seen as tracers. Export of solute is modeled through a recently developed framework which accounts for nonstationary travel time distributions where we parameterize how output fluxes (namely, discharge and evapotranspiration) sample the available water ages in storage. The relevance of this work lies in the study of hydrologic drivers of the nonstationary character of residence and travel time distributions, whose definition and computation shape this theoretical transport study. Our results show that a large fraction of the different behaviors exhibited by the tracers may be charged to the variability of the hydrologic forcings experienced after the injection. Moreover, the results highlight the crucial, and often overlooked, role of evapotranspiration and plant uptake in determining the transport of water and solutes. This application also suggests that the ways evapotranspiration selects water with different ages in storage can be inferred through model calibration contrasting only tracer concentrations in the discharge. A view on upscaled transport volumes like hillslopes or catchments is maintained throughout the paper.

  15. Theoretical modeling of single-molecule fluorescence with complicated photon statistics

    NASA Astrophysics Data System (ADS)

    Osad'ko, I. S.; Naumov, A. V.; Eremchev, I. Yu.; Vainer, Yu. G.; Kador, L.

    2012-11-01

    The use of techniques for analyzing the fluorescence photon statistics of a single molecule for modeling single-emitter dynamics is demonstrated. The photon distribution function measured in the fluorescence of a single tetra-tert-butylterrylene molecule embedded in polyisobutylene is used to devise a theoretical model for single emitters with complicated fluorescence photon statistics. Our analysis was carried out with the theoretical approach developed by Osad'ko and co-workers [J. Chem. Phys.JCPSA60021-960610.1063/1.3055287 130, 064904 (2009); J. Phys. Chem. C10.1021/jp1014093 114, 10349 (2010)] for photon distribution functions. Although the experimental data were obtained at cryogenic temperature where narrow zero-phonon lines are present, the method is based on a purely statistical approach and does not require spectrally resolved data. It can also be applied to the analysis of broad fluorescence bands as measured at room temperature. Therefore, the method has prospects for revealing the quantum dynamics of single biological objects and other single quantum emitters in ambient conditions.

  16. A model-based analysis of a display for helicopter landing approach. [control theoretical model of human pilot

    NASA Technical Reports Server (NTRS)

    Hess, R. A.; Wheat, L. W.

    1975-01-01

    A control theoretic model of the human pilot was used to analyze a baseline electronic cockpit display in a helicopter landing approach task. The head down display was created on a stroke written cathode ray tube and the vehicle was a UH-1H helicopter. The landing approach task consisted of maintaining prescribed groundspeed and glideslope in the presence of random vertical and horizontal turbulence. The pilot model was also used to generate and evaluate display quickening laws designed to improve pilot vehicle performance. A simple fixed base simulation provided comparative tracking data.

  17. Regulatory acceptance of animal models of disease to support clinical trials of medicines and advanced therapy medicinal products.

    PubMed

    Cavagnaro, Joy; Silva Lima, Beatriz

    2015-07-15

    The utility of animal models of disease for assessing the safety of novel therapeutic modalities has become an increasingly important topic of discussion as research and development efforts focus on improving the predictive value of animal studies to support accelerated clinical development. Medicines are approved for marketing based upon a determination that their benefits outweigh foreseeable risks in specific indications, specific populations, and at specific dosages and regimens. No medicine is 100% safe. A medicine is less safe if the actual risks are greater than the predicted risks. The purpose of preclinical safety assessment is to understand the potential risks to aid clinical decision-making. Ideally preclinical studies should identify potential adverse effects and design clinical studies that will minimize their occurrence. Most regulatory documents delineate the utilization of conventional "normal" animal species to evaluate the safety risk of new medicines (i.e., new chemical entities and new biological entities). Animal models of human disease are commonly utilized to gain insight into the pathogenesis of disease and to evaluate efficacy but less frequently utilized in preclinical safety assessment. An understanding of the limitations of the animal disease models together with a better understanding of the disease and how toxicity may be impacted by the disease condition should allow for a better prediction of risk in the intended patient population. Importantly, regulatory authorities are becoming more willing to accept and even recommend data from experimental animal disease models that combine efficacy and safety to support clinical development.

  18. Regulatory acceptance of animal models of disease to support clinical trials of medicines and advanced therapy medicinal products.

    PubMed

    Cavagnaro, Joy; Silva Lima, Beatriz

    2015-07-15

    The utility of animal models of disease for assessing the safety of novel therapeutic modalities has become an increasingly important topic of discussion as research and development efforts focus on improving the predictive value of animal studies to support accelerated clinical development. Medicines are approved for marketing based upon a determination that their benefits outweigh foreseeable risks in specific indications, specific populations, and at specific dosages and regimens. No medicine is 100% safe. A medicine is less safe if the actual risks are greater than the predicted risks. The purpose of preclinical safety assessment is to understand the potential risks to aid clinical decision-making. Ideally preclinical studies should identify potential adverse effects and design clinical studies that will minimize their occurrence. Most regulatory documents delineate the utilization of conventional "normal" animal species to evaluate the safety risk of new medicines (i.e., new chemical entities and new biological entities). Animal models of human disease are commonly utilized to gain insight into the pathogenesis of disease and to evaluate efficacy but less frequently utilized in preclinical safety assessment. An understanding of the limitations of the animal disease models together with a better understanding of the disease and how toxicity may be impacted by the disease condition should allow for a better prediction of risk in the intended patient population. Importantly, regulatory authorities are becoming more willing to accept and even recommend data from experimental animal disease models that combine efficacy and safety to support clinical development. PMID:25814257

  19. Theoretical uncertainties due to AGN subgrid models in predictions of galaxy cluster observable properties

    NASA Astrophysics Data System (ADS)

    Yang, H.-Y. Karen; Sutter, P. M.; Ricker, Paul M.

    2012-12-01

    Cosmological constraints derived from galaxy clusters rely on accurate predictions of cluster observable properties, in which feedback from active galactic nuclei (AGN) is a critical component. In order to model the physical effects due to supermassive black holes (SMBH) on cosmological scales, subgrid modelling is required, and a variety of implementations have been developed in the literature. However, theoretical uncertainties due to model and parameter variations are not yet well understood, limiting the predictive power of simulations including AGN feedback. By performing a detailed parameter-sensitivity study in a single cluster using several commonly adopted AGN accretion and feedback models with FLASH, we quantify the model uncertainties in predictions of cluster integrated properties. We find that quantities that are more sensitive to gas density have larger uncertainties (˜20 per cent for Mgas and a factor of ˜2 for LX at R500), whereas TX, YSZ and YX are more robust (˜10-20 per cent at R500). To make predictions beyond this level of accuracy would require more constraints on the most relevant parameters: the accretion model, mechanical heating efficiency and size of feedback region. By studying the impact of AGN feedback on the scaling relations, we find that an anti-correlation exists between Mgas and TX, which is another reason why YSZ and YX are excellent mass proxies. This anti-correlation also implies that AGN feedback is likely to be an important source of intrinsic scatter in the Mgas-TX and LX-TX relations.

  20. Accountability and pediatric physician-researchers: are theoretical models compatible with Canadian lived experience?

    PubMed Central

    2011-01-01

    Physician-researchers are bound by professional obligations stemming from both the role of the physician and the role of the researcher. Currently, the dominant models for understanding the relationship between physician-researchers' clinical duties and research duties fit into three categories: the similarity position, the difference position and the middle ground. The law may be said to offer a fourth "model" that is independent from these three categories. These models frame the expectations placed upon physician-researchers by colleagues, regulators, patients and research participants. This paper examines the extent to which the data from semi-structured interviews with 30 physician-researchers at three major pediatric hospitals in Canada reflect these traditional models. It seeks to determine the extent to which existing models align with the described lived experience of the pediatric physician-researchers interviewed. Ultimately, we find that although some physician-researchers make references to something like the weak version of the similarity position, the pediatric-researchers interviewed in this study did not describe their dual roles in a way that tightly mirrors any of the existing theoretical frameworks. We thus conclude that either physician-researchers are in need of better training regarding the nature of the accountability relationships that flow from their dual roles or that models setting out these roles and relationships must be altered to better reflect what we can reasonably expect of physician-researchers in a real-world environment. PMID:21974866

  1. Accountability and pediatric physician-researchers: are theoretical models compatible with Canadian lived experience?

    PubMed

    Czoli, Christine; Da Silva, Michael; Shaul, Randi Zlotnik; d'Agincourt-Canning, Lori; Simpson, Christy; Boydell, Katherine; Rashkovan, Natalie; Vanin, Sharon

    2011-01-01

    Physician-researchers are bound by professional obligations stemming from both the role of the physician and the role of the researcher. Currently, the dominant models for understanding the relationship between physician-researchers' clinical duties and research duties fit into three categories: the similarity position, the difference position and the middle ground. The law may be said to offer a fourth "model" that is independent from these three categories.These models frame the expectations placed upon physician-researchers by colleagues, regulators, patients and research participants. This paper examines the extent to which the data from semi-structured interviews with 30 physician-researchers at three major pediatric hospitals in Canada reflect these traditional models. It seeks to determine the extent to which existing models align with the described lived experience of the pediatric physician-researchers interviewed.Ultimately, we find that although some physician-researchers make references to something like the weak version of the similarity position, the pediatric-researchers interviewed in this study did not describe their dual roles in a way that tightly mirrors any of the existing theoretical frameworks. We thus conclude that either physician-researchers are in need of better training regarding the nature of the accountability relationships that flow from their dual roles or that models setting out these roles and relationships must be altered to better reflect what we can reasonably expect of physician-researchers in a real-world environment. PMID:21974866

  2. Implications of resonant inelastic x-ray scattering data for theoretical models of cuprates

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Sushkov, Oleg P.

    2013-11-01

    There are two commonly discussed points of view in theoretical description of cuprate superconductors: (i) Cuprates can be described by the modified t-J model; (ii) overdoped cuprates are close to the regime of normal Fermi liquid (NFL). We argue that recent resonant inelastic x-ray scattering data challenge both points. While the modified t-J model describes well the strongly underdoped regime, it fails to describe high energy magnetic excitations when approaching optimal doping. This probably indicates failure of the Zhang-Rice singlet picture. In the overdoped regime the momentum-integrated spin structure factor S(ω) has the same intensity and energy distribution as that in an undoped parent compound. This implies that the entire spin spectral sum rule is saturated at ω≈2J, while in an NFL the spectral weight should saturate only at the total bandwidth which is much larger than 2J.

  3. Toward a unifying model of identification with groups: integrating theoretical perspectives.

    PubMed

    Roccas, Sonia; Sagiv, Lilach; Schwartz, Shalom; Halevy, Nir; Eidelson, Roy

    2008-08-01

    Building on the contributions of diverse theoretical approaches, the authors present a multidimensional model of group identification. Integrating conceptions from the social identity perspective with those from research on individualism-collectivism, nationalism- patriotism, and identification with organizations, we propose four conceptually distinct modes of identification: importance (how much I view the group as part of who I am), commitment (how much I want to benefit the group), superiority (how much I view my group as superior to other groups), and deference (how much I honor, revere, and submit to the group's norms, symbols, and leaders). We present an instrument for assessing the four modes of identification and review initial empirical findings that validate the proposed model and show its utility in understanding antecedents and consequences of identification. PMID:18641386

  4. Angular anisotropy in valence photoionization of Na clusters: theoretical investigation using jellium model

    NASA Astrophysics Data System (ADS)

    Jänkälä, Kari

    2013-03-01

    Calculation of the behaviour of photoelectron angular anisotropy in valence ionization of initially neutral NaX (X = 34-58) clusters is provided. The calculations are carried out for 1p, 1d and 1g jellium orbitals as a function of photon energy. The adapted theoretical framework is spherical jellium model using Woods-Saxon potential, which is modified to account for the long-range Coulomb tail in the final state. We discuss on the observed dramatic variations of the angular anisotropy parameter β as a function incident photon energy. It is shown that the behaviour is connected to the oscillation of the valence photoionization cross sections, that is a specific interference property of such metallic clusters whose valence structure can be described using the jellium model. ISSPIC 16 - 16th International Symposium on Small Particles and Inorganic Clusters, edited by Kristiaan Temst, Margriet J. Van Bael, Ewald Janssens, H.-G. Boyen and Françoise Remacle.

  5. Food addiction spectrum: a theoretical model from normality to eating and overeating disorders.

    PubMed

    Piccinni, Armando; Marazziti, Donatella; Vanelli, Federica; Franceschini, Caterina; Baroni, Stefano; Costanzo, Davide; Cremone, Ivan Mirko; Veltri, Antonello; Dell'Osso, Liliana

    2015-01-01

    The authors comment on the recently proposed food addiction spectrum that represents a theoretical model to understand the continuum between several conditions ranging from normality to pathological states, including eating disorders and obesity, as well as why some individuals show a peculiar attachment to food that can become an addiction. Further, they review the possible neurobiological underpinnings of these conditions that include dopaminergic neurotransmission and circuits that have long been implicated in drug addiction. The aim of this article is also that at stimulating a debate regarding the possible model of a food (or eating) addiction spectrum that may be helpful towards the search of novel therapeutic approaches to different pathological states related to disturbed feeding or overeating.

  6. From moral theory to penal attitudes and back: a theoretically integrated modeling approach.

    PubMed

    de Keijser, Jan W; van der Leeden, Rien; Jackson, Janet L

    2002-01-01

    From a moral standpoint, we would expect the practice of punishment to reflect a solid and commonly shared legitimizing framework. Several moral legal theories explicitly aim to provide such frameworks. Based on the theories of Retributivism, Utilitarianism, and Restorative Justice, this article first sets out to develop a theoretically integrated model of penal attitudes and then explores the extent to which Dutch judges' attitudes to punishment fit the model. Results indicate that penal attitudes can be measured in a meaningful way that is consistent with an integrated approach to moral theory. The general structure of penal attitudes among Dutch judges suggests a streamlined and pragmatic approach to legal punishment that is identifiably founded on the separate concepts central to moral theories of punishment. While Restorative Justice is frequently presented as an alternative paradigm, results show it to be smoothly incorporated within the streamlined approach.

  7. The self-schema model: a theoretical approach to the self-concept in eating disorders.

    PubMed

    Stein, K F

    1996-04-01

    Over the last several decades, the self-concept has been implicated as a important determinant of eating disorders (ED). Although considerable progress has been made, questions remain unanswered about the properties of self-concept that distinguish women with an ED from other populations, and mechanisms that link the self-concept to the disordered behaviors. Markus's self-schema model is presented as a theoretical approach to explore the role of the self-concept in ED. To show how the schema model can be integrated with existing work on the self-concept in ED, a framework is proposed that addresses the number, content, and accessibility of the self-schemas. More specifically, it is posited that a limited collection of positive self-schemas available in memory, in combination with a chronically and inflexibly accessible body-weight self-schema, lead to the disordered behaviors associated with anorexia nervosa and bulimia nervosa.

  8. Toward a unifying model of identification with groups: integrating theoretical perspectives.

    PubMed

    Roccas, Sonia; Sagiv, Lilach; Schwartz, Shalom; Halevy, Nir; Eidelson, Roy

    2008-08-01

    Building on the contributions of diverse theoretical approaches, the authors present a multidimensional model of group identification. Integrating conceptions from the social identity perspective with those from research on individualism-collectivism, nationalism- patriotism, and identification with organizations, we propose four conceptually distinct modes of identification: importance (how much I view the group as part of who I am), commitment (how much I want to benefit the group), superiority (how much I view my group as superior to other groups), and deference (how much I honor, revere, and submit to the group's norms, symbols, and leaders). We present an instrument for assessing the four modes of identification and review initial empirical findings that validate the proposed model and show its utility in understanding antecedents and consequences of identification.

  9. Examining the Intention to Use Technology among Pre-Service Teachers: An Integration of the Technology Acceptance Model and Theory of Planned Behavior

    ERIC Educational Resources Information Center

    Teo, Timothy

    2012-01-01

    This study examined pre-service teachers' self-reported intention to use technology. One hundred fifty-seven participants completed a survey questionnaire measuring their responses to six constructs from a research model that integrated the Technology Acceptance Model (TAM) and Theory of Planned Behavior (TPB). Structural equation modeling was…

  10. Factors That Influence the Acceptance of Telemetry by Emergency Medical Technicians in Ambulances: An Application of the Extended Technology Acceptance Model

    PubMed Central

    Hwang, Ji Young; Kim, Ki Young

    2014-01-01

    Abstract Objective: The aim of the study was to verify the effects of patient factors perceived by emergency medical technicians (EMTs) as well as their social and organizational factors on prehospital telemetry use intention based on the technology use intention and elaboration likelihood models. Materials and Methods: This is a retrospective empirical study. Questionnaires were developed on the basis of clinical factors of 72,907 patients assessed by prehospital telemetry from January 1, 2009 to April 30, 2012 by reviewing their prehospital medical care records and in-hospital medical records. Questionnaires regarding the social and organizational factors of EMTs were created on the basis of a literature review. To verify which factors affect the utilization of telemetry, we developed a partial least-squares route model on the basis of each characteristic. In total, 136 EMTs who had experience in using prehospital telemetry were surveyed from April 1 to April 7, 2013. Reliability, validity, hypotheses, and the model goodness of fit of the study tools were tested. Results: The clinical factors of the patients (path coefficient=−0.12; t=2.38), subjective norm (path coefficient=0.18; t=2.63), and job fit (path coefficient=0.45; t=5.29) positively affected the perceived usefulness (p<0.010). Meanwhile, the clinical factors of the patients (path coefficients=−0.19; t=4.46), subjective norm (path coefficient=0.08; t=1.97), loyalty incentives (path coefficient=−0.17; t=3.83), job fit (path coefficient=−0.32; t=7.06), organizational facilitations (path coefficient=0.08; t=1.99), and technical factors (i.e., usefulness and ease of use) positively affected attitudes (path coefficient=0.10, 0.58; t=2.62, 5.81; p<0.010). Attitudes and perceived usefulness significantly positively affected use intention. Conclusions: Factors that influence the use of telemetry by EMTs in ambulances included patients' clinical factors, as well as complex organizational and

  11. Comparison of statistical and theoretical habitat models for conservation planning: the benefit of ensemble prediction

    USGS Publications Warehouse

    Jones-Farrand, D. Todd; Fearer, Todd M.; Thogmartin, Wayne E.; Thompson, Frank R.; Nelson, Mark D.; Tirpak, John M.

    2011-01-01

    Selection of a modeling approach is an important step in the conservation planning process, but little guidance is available. We compared two statistical and three theoretical habitat modeling approaches representing those currently being used for avian conservation planning at landscape and regional scales: hierarchical spatial count (HSC), classification and regression tree (CRT), habitat suitability index (HSI), forest structure database (FS), and habitat association database (HA). We focused our comparison on models for five priority forest-breeding species in the Central Hardwoods Bird Conservation Region: Acadian Flycatcher, Cerulean Warbler, Prairie Warbler, Red-headed Woodpecker, and Worm-eating Warbler. Lacking complete knowledge on the distribution and abundance of each species with which we could illuminate differences between approaches and provide strong grounds for recommending one approach over another, we used two approaches to compare models: rank correlations among model outputs and comparison of spatial correspondence. In general, rank correlations were significantly positive among models for each species, indicating general agreement among the models. Worm-eating Warblers had the highest pairwise correlations, all of which were significant (P , 0.05). Red-headed Woodpeckers had the lowest agreement among models, suggesting greater uncertainty in the relative conservation value of areas within the region. We assessed model uncertainty by mapping the spatial congruence in priorities (i.e., top ranks) resulting from each model for each species and calculating the coefficient of variation across model ranks for each location. This allowed identification of areas more likely to be good targets of conservation effort for a species, those areas that were least likely, and those in between where uncertainty is higher and thus conservation action incorporates more risk. Based on our results, models developed independently for the same purpose

  12. Defense of Cyber Infrastructures Against Cyber-Physical Attacks Using Game-Theoretic Models.

    PubMed

    Rao, Nageswara S V; Poole, Stephen W; Ma, Chris Y T; He, Fei; Zhuang, Jun; Yau, David K Y

    2016-04-01

    The operation of cyber infrastructures relies on both cyber and physical components, which are subject to incidental and intentional degradations of different kinds. Within the context of network and computing infrastructures, we study the strategic interactions between an attacker and a defender using game-theoretic models that take into account both cyber and physical components. The attacker and defender optimize their individual utilities, expressed as sums of cost and system terms. First, we consider a Boolean attack-defense model, wherein the cyber and physical subinfrastructures may be attacked and reinforced as individual units. Second, we consider a component attack-defense model wherein their components may be attacked and defended, and the infrastructure requires minimum numbers of both to function. We show that the Nash equilibrium under uniform costs in both cases is computable in polynomial time, and it provides high-level deterministic conditions for the infrastructure survival. When probabilities of successful attack and defense, and of incidental failures, are incorporated into the models, the results favor the attacker but otherwise remain qualitatively similar. This approach has been motivated and validated by our experiences with UltraScience Net infrastructure, which was built to support high-performance network experiments. The analytical results, however, are more general, and we apply them to simplified models of cloud and high-performance computing infrastructures.

  13. Defense of Cyber Infrastructures Against Cyber-Physical Attacks Using Game-Theoretic Models.

    PubMed

    Rao, Nageswara S V; Poole, Stephen W; Ma, Chris Y T; He, Fei; Zhuang, Jun; Yau, David K Y

    2016-04-01

    The operation of cyber infrastructures relies on both cyber and physical components, which are subject to incidental and intentional degradations of different kinds. Within the context of network and computing infrastructures, we study the strategic interactions between an attacker and a defender using game-theoretic models that take into account both cyber and physical components. The attacker and defender optimize their individual utilities, expressed as sums of cost and system terms. First, we consider a Boolean attack-defense model, wherein the cyber and physical subinfrastructures may be attacked and reinforced as individual units. Second, we consider a component attack-defense model wherein their components may be attacked and defended, and the infrastructure requires minimum numbers of both to function. We show that the Nash equilibrium under uniform costs in both cases is computable in polynomial time, and it provides high-level deterministic conditions for the infrastructure survival. When probabilities of successful attack and defense, and of incidental failures, are incorporated into the models, the results favor the attacker but otherwise remain qualitatively similar. This approach has been motivated and validated by our experiences with UltraScience Net infrastructure, which was built to support high-performance network experiments. The analytical results, however, are more general, and we apply them to simplified models of cloud and high-performance computing infrastructures. PMID:25847370

  14. Defense of Cyber Infrastructures Against Cyber-Physical Attacks Using Game-Theoretic Models

    DOE PAGES

    Rao, Nageswara S. V.; Poole, Stephen W.; Ma, Chris Y. T.; He, Fei; Zhuang, Jun; Yau, David K. Y.

    2015-04-06

    The operation of cyber infrastructures relies on both cyber and physical components, which are subject to incidental and intentional degradations of different kinds. Within the context of network and computing infrastructures, we study the strategic interactions between an attacker and a defender using game-theoretic models that take into account both cyber and physical components. The attacker and defender optimize their individual utilities expressed as sums of cost and system terms. First, we consider a Boolean attack-defense model, wherein the cyber and physical sub-infrastructures may be attacked and reinforced as individual units. Second, we consider a component attack-defense model wherein theirmore » components may be attacked and defended, and the infrastructure requires minimum numbers of both to function. We show that the Nash equilibrium under uniform costs in both cases is computable in polynomial time, and it provides high-level deterministic conditions for the infrastructure survival. When probabilities of successful attack and defense, and of incidental failures are incorporated into the models, the results favor the attacker but otherwise remain qualitatively similar. This approach has been motivated and validated by our experiences with UltraScience Net infrastructure, which was built to support high-performance network experiments. In conclusion, the analytical results, however, are more general, and we apply them to simplified models of cloud and high-performance computing infrastructures.« less

  15. Defense of Cyber Infrastructures Against Cyber-Physical Attacks Using Game-Theoretic Models

    SciTech Connect

    Rao, Nageswara S. V.; Poole, Stephen W.; Ma, Chris Y. T.; He, Fei; Zhuang, Jun; Yau, David K. Y.

    2015-04-06

    The operation of cyber infrastructures relies on both cyber and physical components, which are subject to incidental and intentional degradations of different kinds. Within the context of network and computing infrastructures, we study the strategic interactions between an attacker and a defender using game-theoretic models that take into account both cyber and physical components. The attacker and defender optimize their individual utilities expressed as sums of cost and system terms. First, we consider a Boolean attack-defense model, wherein the cyber and physical sub-infrastructures may be attacked and reinforced as individual units. Second, we consider a component attack-defense model wherein their components may be attacked and defended, and the infrastructure requires minimum numbers of both to function. We show that the Nash equilibrium under uniform costs in both cases is computable in polynomial time, and it provides high-level deterministic conditions for the infrastructure survival. When probabilities of successful attack and defense, and of incidental failures are incorporated into the models, the results favor the attacker but otherwise remain qualitatively similar. This approach has been motivated and validated by our experiences with UltraScience Net infrastructure, which was built to support high-performance network experiments. In conclusion, the analytical results, however, are more general, and we apply them to simplified models of cloud and high-performance computing infrastructures.

  16. Theoretical model for coupled radial and translational motion of two bubbles at arbitrary separation distances.

    PubMed

    Doinikov, Alexander A; Bouakaz, Ayache

    2015-10-01

    A theoretical model is developed that describes nonlinear spherical pulsations and translational motions of two interacting bubbles at arbitrary separation distances between the bubbles. The derivation of the model is based on the multipole expansion of the bubble velocity potentials and the use of the Lagrangian formalism. The model consists of four coupled ordinary differential equations. Two of them are modified Rayleigh-Plesset equations for the radial oscillations of the bubbles and the other two describe the translational displacement of the bubble centers. The equations are not subject to the assumption that the distance between the bubbles is large compared to the bubble radii and hence make it possible to simulate the bubble dynamics starting from large separation distances up to contact between the bubbles providing that the deviation of the bubble shape from sphericity is negligible. Numerical simulations are carried out to demonstrate the capabilities of the developed model. It is shown that the correct modeling of the translational dynamics of the bubbles at small separation distances requires terms accurate up to ninth order in the inverse separation distance. Physical mechanisms are analyzed that lead to the change of the direction of the relative translational motion of the bubbles in finite-amplitude acoustic fields.

  17. MIP models for connected facility location: A theoretical and computational study☆

    PubMed Central

    Gollowitzer, Stefan; Ljubić, Ivana

    2011-01-01

    This article comprises the first theoretical and computational study on mixed integer programming (MIP) models for the connected facility location problem (ConFL). ConFL combines facility location and Steiner trees: given a set of customers, a set of potential facility locations and some inter-connection nodes, ConFL searches for the minimum-cost way of assigning each customer to exactly one open facility, and connecting the open facilities via a Steiner tree. The costs needed for building the Steiner tree, facility opening costs and the assignment costs need to be minimized. We model ConFL using seven compact and three mixed integer programming formulations of exponential size. We also show how to transform ConFL into the Steiner arborescence problem. A full hierarchy between the models is provided. For two exponential size models we develop a branch-and-cut algorithm. An extensive computational study is based on two benchmark sets of randomly generated instances with up to 1300 nodes and 115,000 edges. We empirically compare the presented models with respect to the quality of obtained bounds and the corresponding running time. We report optimal values for all but 16 instances for which the obtained gaps are below 0.6%. PMID:25009366

  18. Theoretical vibro-acoustic modeling of acoustic noise transmission through aircraft windows

    NASA Astrophysics Data System (ADS)

    Aloufi, Badr; Behdinan, Kamran; Zu, Jean

    2016-06-01

    In this paper, a fully vibro-acoustic model for sound transmission across a multi-pane aircraft window is developed. The proposed model is efficiently applied for a set of window models to perform extensive theoretical parametric studies. The studied window configurations generally simulate the passenger window designs of modern aircraft classes which have an exterior multi-Plexiglas pane, an interior single acrylic glass pane and a dimmable glass ("smart" glass), all separated by thin air cavities. The sound transmission loss (STL) characteristics of three different models, triple-, quadruple- and quintuple-paned windows identical in size and surface density, are analyzed for improving the acoustic insulation performances. Typical results describing the influence of several system parameters, such as the thicknesses, number and spacing of the window panes, on the transmission loss are then investigated. In addition, a comparison study is carried out to evaluate the acoustic reduction capability of each window model. The STL results show that the higher frequencies sound transmission loss performance can be improved by increasing the number of window panels, however, the low frequency performance is decreased, particularly at the mass-spring resonances.

  19. Analysis of the technology acceptance model in examining hospital nurses' behavioral intentions toward the use of bar code medication administration.

    PubMed

    Song, Lunar; Park, Byeonghwa; Oh, Kyeung Mi

    2015-04-01

    Serious medication errors continue to exist in hospitals, even though there is technology that could potentially eliminate them such as bar code medication administration. Little is known about the degree to which the culture of patient safety is associated with behavioral intention to use bar code medication administration. Based on the Technology Acceptance Model, this study evaluated the relationships among patient safety culture and perceived usefulness and perceived ease of use, and behavioral intention to use bar code medication administration technology among nurses in hospitals. Cross-sectional surveys with a convenience sample of 163 nurses using bar code medication administration were conducted. Feedback and communication about errors had a positive impact in predicting perceived usefulness (β=.26, P<.01) and perceived ease of use (β=.22, P<.05). In a multiple regression model predicting for behavioral intention, age had a negative impact (β=-.17, P<.05); however, teamwork within hospital units (β=.20, P<.05) and perceived usefulness (β=.35, P<.01) both had a positive impact on behavioral intention. The overall bar code medication administration behavioral intention model explained 24% (P<.001) of the variance. Identified factors influencing bar code medication administration behavioral intention can help inform hospitals to develop tailored interventions for RNs to reduce medication administration errors and increase patient safety by using this technology.

  20. Why was Relativity Accepted?

    NASA Astrophysics Data System (ADS)

    Brush, S. G.

    Historians of science have published many studies of the reception of Einstein's special and general theories of relativity. Based on a review of these studies, and my own research on the role of the light-bending prediction in the reception of general relativity, I discuss the role of three kinds of reasons for accepting relativity (1) empirical predictions and explanations; (2) social-psychological factors; and (3) aesthetic-mathematical factors. According to the historical studies, acceptance was a three-stage process. First, a few leading scientists adopted the special theory for aesthetic-mathematical reasons. In the second stage, their enthusiastic advocacy persuaded other scientists to work on the theory and apply it to problems currently of interest in atomic physics. The special theory was accepted by many German physicists by 1910 and had begun to attract some interest in other countries. In the third stage, the confirmation of Einstein's light-bending prediction attracted much public attention and forced all physicists to take the general theory of relativity seriously. In addition to light-bending, the explanation of the advance of Mercury's perihelion was considered strong evidence by theoretical physicists. The American astronomers who conducted successful tests of general relativity became defenders of the theory. There is little evidence that relativity was `socially constructed' but its initial acceptance was facilitated by the prestige and resources of its advocates.