WorldWideScience

Sample records for model qualitatively describes

  1. Frameworks for understanding and describing business models

    DEFF Research Database (Denmark)

    Nielsen, Christian; Roslender, Robin

    2014-01-01

    This chapter provides in a chronological fashion an introduction to six frameworks that one can apply to describing, understanding and also potentially innovating business models. These six frameworks have been chosen carefully as they represent six very different perspectives on business models...... and in this manner “complement” each other. There are a multitude of varying frameworks that could be chosen from and we urge the reader to search and trial these for themselves. The six chosen models (year of release in parenthesis) are: • Service-Profit Chain (1994) • Strategic Systems Auditing (1997) • Strategy...... Maps (2001) • Intellectual Capital Statements (2003) • Chesbrough’s framework for Open Business Models (2006) • Business Model Canvas (2008)...

  2. Inhomogeneous Markov Models for Describing Driving Patterns

    DEFF Research Database (Denmark)

    Iversen, Emil Banning; Møller, Jan K.; Morales, Juan Miguel

    2017-01-01

    . Specifically, an inhomogeneous Markov model that captures the diurnal variation in the use of a vehicle is presented. The model is defined by the time-varying probabilities of starting and ending a trip, and is justified due to the uncertainty associated with the use of the vehicle. The model is fitted to data...... collected from the actual utilization of a vehicle. Inhomogeneous Markov models imply a large number of parameters. The number of parameters in the proposed model is reduced using B-splines....

  3. Inhomogeneous Markov Models for Describing Driving Patterns

    DEFF Research Database (Denmark)

    Iversen, Jan Emil Banning; Møller, Jan Kloppenborg; Morales González, Juan Miguel

    . Specically, an inhomogeneous Markov model that captures the diurnal variation in the use of a vehicle is presented. The model is dened by the time-varying probabilities of starting and ending a trip and is justied due to the uncertainty associated with the use of the vehicle. The model is tted to data...... collected from the actual utilization of a vehicle. Inhomogeneous Markov models imply a large number of parameters. The number of parameters in the proposed model is reduced using B-splines....

  4. Using Metaphorical Models for Describing Glaciers

    Science.gov (United States)

    Felzmann, Dirk

    2014-01-01

    To date, there has only been little conceptual change research regarding conceptions about glaciers. This study used the theoretical background of embodied cognition to reconstruct different metaphorical concepts with respect to the structure of a glacier. Applying the Model of Educational Reconstruction, the conceptions of students and scientists…

  5. Modeling Approaches for Describing Microbial Population Heterogeneity

    DEFF Research Database (Denmark)

    Lencastre Fernandes, Rita

    environmental conditions. Three cases are presented and discussed in this thesis. Common to all is the use of S. cerevisiae as model organism, and the use of cell size and cell cycle position as single-cell descriptors. The first case focuses on the experimental and mathematical description of a yeast...

  6. Describing qualitative research undertaken with randomised controlled trials in grant proposals: a documentary analysis.

    Science.gov (United States)

    Drabble, Sarah J; O'Cathain, Alicia; Thomas, Kate J; Rudolph, Anne; Hewison, Jenny

    2014-02-18

    There is growing recognition of the value of conducting qualitative research with trials in health research. It is timely to reflect on how this qualitative research is presented in grant proposals to identify lessons for researchers and research commissioners. As part of a larger study focusing on how to maximise the value of undertaking qualitative research with trials, we undertook a documentary analysis of proposals of funded studies. Using the metaRegister of Controlled Trials (mRCT) database we identified trials funded in the United Kingdom, ongoing between 2001 and 2010, and reporting the use of qualitative research. We requested copies of proposals from lead researchers. We extracted data from the proposals using closed and open questions, analysed using descriptive statistics and content analysis respectively. 2% (89/3812) of trials in the mRCT database described the use of qualitative research undertaken with the trial. From these 89 trials, we received copies of 36 full proposals, of which 32 met our inclusion criteria. 25% used less than a single paragraph to describe the qualitative research. The aims of the qualitative research described in these proposals focused mainly on the intervention or trial conduct. Just over half (56%) of the proposals included an explicit rationale for conducting the qualitative research with the trial, the most frequent being to optimise implementation into clinical practice or to interpret trial findings. Key information about methods, expertise and resources was missing in a large minority of proposals, in particular sample size, type of analysis, and non-personnel resources. 28% specifically stated that qualitative researchers would conduct the qualitative research. Our review of proposals of successfully funded studies identified good practice but also identified limited space given to describing the qualitative research, with an associated lack of attention to the rationale for doing the qualitative research and

  7. Describing qualitative research undertaken with randomised controlled trials in grant proposals: a documentary analysis

    Science.gov (United States)

    2014-01-01

    Background There is growing recognition of the value of conducting qualitative research with trials in health research. It is timely to reflect on how this qualitative research is presented in grant proposals to identify lessons for researchers and research commissioners. As part of a larger study focusing on how to maximise the value of undertaking qualitative research with trials, we undertook a documentary analysis of proposals of funded studies. Methods Using the metaRegister of Controlled Trials (mRCT) database we identified trials funded in the United Kingdom, ongoing between 2001 and 2010, and reporting the use of qualitative research. We requested copies of proposals from lead researchers. We extracted data from the proposals using closed and open questions, analysed using descriptive statistics and content analysis respectively. Results 2% (89/3812) of trials in the mRCT database described the use of qualitative research undertaken with the trial. From these 89 trials, we received copies of 36 full proposals, of which 32 met our inclusion criteria. 25% used less than a single paragraph to describe the qualitative research. The aims of the qualitative research described in these proposals focused mainly on the intervention or trial conduct. Just over half (56%) of the proposals included an explicit rationale for conducting the qualitative research with the trial, the most frequent being to optimise implementation into clinical practice or to interpret trial findings. Key information about methods, expertise and resources was missing in a large minority of proposals, in particular sample size, type of analysis, and non-personnel resources. 28% specifically stated that qualitative researchers would conduct the qualitative research. Conclusions Our review of proposals of successfully funded studies identified good practice but also identified limited space given to describing the qualitative research, with an associated lack of attention to the rationale for

  8. Computer modeling describes gravity-related adaptation in cell cultures.

    Science.gov (United States)

    Alexandrov, Ludmil B; Alexandrova, Stoyana; Usheva, Anny

    2009-12-16

    Questions about the changes of biological systems in response to hostile environmental factors are important but not easy to answer. Often, the traditional description with differential equations is difficult due to the overwhelming complexity of the living systems. Another way to describe complex systems is by simulating them with phenomenological models such as the well-known evolutionary agent-based model (EABM). Here we developed an EABM to simulate cell colonies as a multi-agent system that adapts to hyper-gravity in starvation conditions. In the model, the cell's heritable characteristics are generated and transferred randomly to offspring cells. After a qualitative validation of the model at normal gravity, we simulate cellular growth in hyper-gravity conditions. The obtained data are consistent with previously confirmed theoretical and experimental findings for bacterial behavior in environmental changes, including the experimental data from the microgravity Atlantis and the Hypergravity 3000 experiments. Our results demonstrate that it is possible to utilize an EABM with realistic qualitative description to examine the effects of hypergravity and starvation on complex cellular entities.

  9. Model checking biological systems described using ambient calculus

    DEFF Research Database (Denmark)

    Mardare, Radu Iulian; Priami, Corrado; Qualia, Paola

    2005-01-01

    Model checking biological systems described using ambient calculus. In Proc. of the second International Workshop on Computational Methods in Systems Biology (CMSB04), Lecture Notes in Bioinformatics 3082:85-103, Springer, 2005.......Model checking biological systems described using ambient calculus. In Proc. of the second International Workshop on Computational Methods in Systems Biology (CMSB04), Lecture Notes in Bioinformatics 3082:85-103, Springer, 2005....

  10. Young women describe the ideal first pelvic examination: Qualitative research using semistructured interviews.

    Science.gov (United States)

    Freyens, Anne; Dejeanne, Mélanie; Fabre, Elise; Rouge-Bugat, Marie-Eve; Oustric, Stéphane

    2017-08-01

    To explore representations of the first pelvic examination (PE) among adolescents who had not yet had this examination and to identify their criteria for a positive experience of it. Qualitative study using semistructured interviews. Midi-Pyrénées and Auvergne in France. Adolescents aged 15 to 19 years who had never had a PE. Participants were recruited through snowball sampling and targeted sampling until data saturation was reached. Maximum variation was sought in the profiles of the study participants. Open-ended questions dealt with the interviewee's sources of information, knowledge of the PE, criteria for a positive PE experience, and representations of the PE itself. Verbatim transcripts were immediately subjected to longitudinal analysis with the context (researchers' notes) and key themes of the interview. Cross-sectional analysis was then performed. Many adolescents lack knowledge about the PE and believe that it is mandatory. According to study participants, the ideal PE would take place when they felt ready. They would be given adequate information in advance and the option of being accompanied by a friend or family member. They described the ideal examining room as warm, comfortable, and reassuring. The quality of their relationship with the examining physician would also affect their acceptance of this examination. An information session before the consultation for the PE would make it possible to reduce the patient's apprehension, improve her level of knowledge, and set the right tone for the upcoming PE, both for her and for the physician. Copyright© the College of Family Physicians of Canada.

  11. Statistical models describing the energy signature of buildings

    DEFF Research Database (Denmark)

    Bacher, Peder; Madsen, Henrik; Thavlov, Anders

    2010-01-01

    Approximately one third of the primary energy production in Denmark is used for heating in buildings. Therefore efforts to accurately describe and improve energy performance of the building mass are very important. For this purpose statistical models describing the energy signature of a building, i...... or varying energy prices. The paper will give an overview of statistical methods and applied models based on experiments carried out in FlexHouse, which is an experimental building in SYSLAB, Risø DTU. The models are of different complexity and can provide estimates of physical quantities such as UA......-values, time constants of the building, and other parameters related to the heat dynamics. A method for selecting the most appropriate model for a given building is outlined and finally a perspective of the applications is given. Aknowledgements to the Danish Energy Saving Trust and the Interreg IV ``Vind i...

  12. Models for describing the thermal characteristics of building components

    DEFF Research Database (Denmark)

    Jimenez, M.J.; Madsen, Henrik

    2008-01-01

    , for example. For the analysis of these tests, dynamic analysis models and methods are required. However, a wide variety of models and methods exists, and the problem of choosing the most appropriate approach for each particular case is a non-trivial and interdisciplinary task. Knowledge of a large family....... The characteristics of each type of model are highlighted. Some available software tools for each of the methods described will be mentioned. A case study also demonstrating the difference between linear and nonlinear models is considered....... of these approaches may therefore be very useful for selecting a suitable approach for each particular case. This paper presents an overview of models that can be applied for modelling the thermal characteristics of buildings and building components using data from outdoor testing. The choice of approach depends...

  13. Icosahedral symmetry described by an incommensurately modulated crystal structure model

    DEFF Research Database (Denmark)

    Wolny, Janusz; Lebech, Bente

    1986-01-01

    A crystal structure model of an incommensurately modulated structure is presented. Although six different reciprocal vectors are used to describe the model, all calculations are done in three dimensions making calculation of the real-space structure trivial. Using this model, it is shown that both...... the positions of the bragg reflections and information about the relative intensities of these reflections are in full accordance with the diffraction patterns reported for microcrystals of the rapidly quenched Al86Mn14 alloy. It is also shown that at least the local structure possesses full icosahedral...

  14. A Model Describing Stable Coherent Synchrotron Radiation in Storage Rings

    International Nuclear Information System (INIS)

    Sannibale, F.

    2004-01-01

    We present a model describing high power stable broadband coherent synchrotron radiation (CSR) in the terahertz frequency region in an electron storage ring. The model includes distortion of bunch shape from the synchrotron radiation (SR), which enhances higher frequency coherent emission, and limits to stable emission due to an instability excited by the SR wakefield. It gives a quantitative explanation of several features of the recent observations of CSR at the BESSY II storage ring. We also use this model to optimize the performance of a source for stable CSR emission

  15. A model describing stable coherent synchrotron radiation in storage rings

    International Nuclear Information System (INIS)

    Sannibale, F.; Byrd, J.M.; Loftsdottir, A.; Venturini, M.; Abo-Bakr, M.; Feikes, J.; Holldack, K.; Kuske, P.; Wuestefeld, G.; Huebers, H.-W.; Warnock, R.

    2004-01-01

    We present a model describing high power stable broadband coherent synchrotron radiation (CSR) in the terahertz frequency region in an electron storage ring. The model includes distortion of bunch shape from the synchrotron radiation (SR), which enhances higher frequency coherent emission, and limits to stable emission due to an instability excited by the SR wakefield. It gives a quantitative explanation of several features of the recent observations of CSR at the BESSY II storage ring. We also use this model to optimize the performance of a source for stable CSR emission

  16. A Kinetic Model Describing Injury-Burden in Team Sports.

    Science.gov (United States)

    Fuller, Colin W

    2017-12-01

    Injuries in team sports are normally characterised by the incidence, severity, and location and type of injuries sustained: these measures, however, do not provide an insight into the variable injury-burden experienced during a season. Injury burden varies according to the team's match and training loads, the rate at which injuries are sustained and the time taken for these injuries to resolve. At the present time, this time-based variation of injury burden has not been modelled. To develop a kinetic model describing the time-based injury burden experienced by teams in elite team sports and to demonstrate the model's utility. Rates of injury were quantified using a large eight-season database of rugby injuries (5253) and exposure (60,085 player-match-hours) in English professional rugby. Rates of recovery from injury were quantified using time-to-recovery analysis of the injuries. The kinetic model proposed for predicting a team's time-based injury burden is based on a composite rate equation developed from the incidence of injury, a first-order rate of recovery from injury and the team's playing load. The utility of the model was demonstrated by examining common scenarios encountered in elite rugby. The kinetic model developed describes and predicts the variable injury-burden arising from match play during a season of rugby union based on the incidence of match injuries, the rate of recovery from injury and the playing load. The model is equally applicable to other team sports and other scenarios.

  17. A model to describe the performance of the UASB reactor.

    Science.gov (United States)

    Rodríguez-Gómez, Raúl; Renman, Gunno; Moreno, Luis; Liu, Longcheng

    2014-04-01

    A dynamic model to describe the performance of the Upflow Anaerobic Sludge Blanket (UASB) reactor was developed. It includes dispersion, advection, and reaction terms, as well as the resistances through which the substrate passes before its biotransformation. The UASB reactor is viewed as several continuous stirred tank reactors connected in series. The good agreement between experimental and simulated results shows that the model is able to predict the performance of the UASB reactor (i.e. substrate concentration, biomass concentration, granule size, and height of the sludge bed).

  18. Using the MWC model to describe heterotropic interactions in hemoglobin

    Science.gov (United States)

    Rapp, Olga

    2017-01-01

    Hemoglobin is a classical model allosteric protein. Research on hemoglobin parallels the development of key cooperativity and allostery concepts, such as the ‘all-or-none’ Hill formalism, the stepwise Adair binding formulation and the concerted Monod-Wymann-Changuex (MWC) allosteric model. While it is clear that the MWC model adequately describes the cooperative binding of oxygen to hemoglobin, rationalizing the effects of H+, CO2 or organophosphate ligands on hemoglobin-oxygen saturation using the same model remains controversial. According to the MWC model, allosteric ligands exert their effect on protein function by modulating the quaternary conformational transition of the protein. However, data fitting analysis of hemoglobin oxygen saturation curves in the presence or absence of inhibitory ligands persistently revealed effects on both relative oxygen affinity (c) and conformational changes (L), elementary MWC parameters. The recent realization that data fitting analysis using the traditional MWC model equation may not provide reliable estimates for L and c thus calls for a re-examination of previous data using alternative fitting strategies. In the current manuscript, we present two simple strategies for obtaining reliable estimates for MWC mechanistic parameters of hemoglobin steady-state saturation curves in cases of both evolutionary and physiological variations. Our results suggest that the simple MWC model provides a reasonable description that can also account for heterotropic interactions in hemoglobin. The results, moreover, offer a general roadmap for successful data fitting analysis using the MWC model. PMID:28793329

  19. HERMES: A Model to Describe Deformation, Burning, Explosion, and Detonation

    Energy Technology Data Exchange (ETDEWEB)

    Reaugh, J E

    2011-11-22

    HERMES (High Explosive Response to MEchanical Stimulus) was developed to fill the need for a model to describe an explosive response of the type described as BVR (Burn to Violent Response) or HEVR (High Explosive Violent Response). Characteristically this response leaves a substantial amount of explosive unconsumed, the time to reaction is long, and the peak pressure developed is low. In contrast, detonations characteristically consume all explosive present, the time to reaction is short, and peak pressures are high. However, most of the previous models to describe explosive response were models for detonation. The earliest models to describe the response of explosives to mechanical stimulus in computer simulations were applied to intentional detonation (performance) of nearly ideal explosives. In this case, an ideal explosive is one with a vanishingly small reaction zone. A detonation is supersonic with respect to the undetonated explosive (reactant). The reactant cannot respond to the pressure of the detonation before the detonation front arrives, so the precise compressibility of the reactant does not matter. Further, the mesh sizes that were practical for the computer resources then available were large with respect to the reaction zone. As a result, methods then used to model detonations, known as {beta}-burn or program burn, were not intended to resolve the structure of the reaction zone. Instead, these methods spread the detonation front over a few finite-difference zones, in the same spirit that artificial viscosity is used to spread the shock front in inert materials over a few finite-difference zones. These methods are still widely used when the structure of the reaction zone and the build-up to detonation are unimportant. Later detonation models resolved the reaction zone. These models were applied both to performance, particularly as it is affected by the size of the charge, and to situations in which the stimulus was less than that needed for reliable

  20. Conceptual hierarchical modeling to describe wetland plant community organization

    Science.gov (United States)

    Little, A.M.; Guntenspergen, G.R.; Allen, T.F.H.

    2010-01-01

    Using multivariate analysis, we created a hierarchical modeling process that describes how differently-scaled environmental factors interact to affect wetland-scale plant community organization in a system of small, isolated wetlands on Mount Desert Island, Maine. We followed the procedure: 1) delineate wetland groups using cluster analysis, 2) identify differently scaled environmental gradients using non-metric multidimensional scaling, 3) order gradient hierarchical levels according to spatiotem-poral scale of fluctuation, and 4) assemble hierarchical model using group relationships with ordination axes and post-hoc tests of environmental differences. Using this process, we determined 1) large wetland size and poor surface water chemistry led to the development of shrub fen wetland vegetation, 2) Sphagnum and water chemistry differences affected fen vs. marsh / sedge meadows status within small wetlands, and 3) small-scale hydrologic differences explained transitions between forested vs. non-forested and marsh vs. sedge meadow vegetation. This hierarchical modeling process can help explain how upper level contextual processes constrain biotic community response to lower-level environmental changes. It creates models with more nuanced spatiotemporal complexity than classification and regression tree procedures. Using this process, wetland scientists will be able to generate more generalizable theories of plant community organization, and useful management models. ?? Society of Wetland Scientists 2009.

  1. Can the "standard" unitarized Regge models describe the TOTEM data?

    CERN Document Server

    Alkin, A; Martynov, E

    2013-01-01

    The standard Regge poles are considered as inputs for two unitarization methods: eikonal and U-matrix. It is shown that only models with three input pomerons and two input odderons can describe the high energy data on $pp$ and $\\bar pp$ elastic scattering including the new data from Tevatron and LHC. However, it seems that the both considered models require a further modification (e.g. nonlinear reggeon trajectories and/or nonexponential vertex functions) for a more satisfactory description of the data at 19.0 GeV$\\leq \\sqrt{s}\\leq$ 7 TeV and 0.01 $\\leq |t|\\leq $14.2 GeV$^{2}$.

  2. Experimental investigation of statistical models describing distribution of counts

    International Nuclear Information System (INIS)

    Salma, I.; Zemplen-Papp, E.

    1992-01-01

    The binomial, Poisson and modified Poisson models which are used for describing the statistical nature of the distribution of counts are compared theoretically, and conclusions for application are considered. The validity of the Poisson and the modified Poisson statistical distribution for observing k events in a short time interval is investigated experimentally for various measuring times. The experiments to measure the influence of the significant radioactive decay were performed with 89 Y m (T 1/2 =16.06 s), using a multichannel analyser (4096 channels) in the multiscaling mode. According to the results, Poisson statistics describe the counting experiment for short measuring times (up to T=0.5T 1/2 ) and its application is recommended. However, analysis of the data demonstrated, with confidence, that for long measurements (T≥T 1/2 ) Poisson distribution is not valid and the modified Poisson function is preferable. The practical implications in calculating uncertainties and in optimizing the measuring time are discussed. Differences between the standard deviations evaluated on the basis of the Poisson and binomial models are especially significant for experiments with long measuring time (T/T 1/2 ≥2) and/or large detection efficiency (ε>0.30). Optimization of the measuring time for paired observations yields the same solution for either the binomial or the Poisson distribution. (orig.)

  3. Qualitative and Quantitative Integrated Modeling for Stochastic Simulation and Optimization

    Directory of Open Access Journals (Sweden)

    Xuefeng Yan

    2013-01-01

    Full Text Available The simulation and optimization of an actual physics system are usually constructed based on the stochastic models, which have both qualitative and quantitative characteristics inherently. Most modeling specifications and frameworks find it difficult to describe the qualitative model directly. In order to deal with the expert knowledge, uncertain reasoning, and other qualitative information, a qualitative and quantitative combined modeling specification was proposed based on a hierarchical model structure framework. The new modeling approach is based on a hierarchical model structure which includes the meta-meta model, the meta-model and the high-level model. A description logic system is defined for formal definition and verification of the new modeling specification. A stochastic defense simulation was developed to illustrate how to model the system and optimize the result. The result shows that the proposed method can describe the complex system more comprehensively, and the survival probability of the target is higher by introducing qualitative models into quantitative simulation.

  4. Communication skills training: describing a new conceptual model.

    Science.gov (United States)

    Brown, Richard F; Bylund, Carma L

    2008-01-01

    Current research in communication in physician-patient consultations is multidisciplinary and multimethodological. As this research has progressed, a considerable body of evidence on the best practices in physician-patient communication has been amassed. This evidence provides a foundation for communication skills training (CST) at all levels of medical education. Although the CST literature has demonstrated that communication skills can be taught, one critique of this literature is that it is not always clear which skills are being taught and whether those skills are matched with those being assessed. The Memorial Sloan-Kettering Cancer Center Comskil Model for CST seeks to answer those critiques by explicitly defining the important components of a consultation, based on Goals, Plans, and Actions theories and sociolinguistic theory. Sequenced guidelines as a mechanism for teaching about particular communication challenges are adapted from these other methods. The authors propose that consultation communication can be guided by an overarching goal, which is achieved through the use of a set of predetermined strategies. Strategies are common in CST; however, strategies often contain embedded communication skills. These skills can exist across strategies, and the Comskil Model seeks to make them explicit in these contexts. Separate from the skills are process tasks and cognitive appraisals that need to be addressed in teaching. The authors also describe how assessment practices foster concordance between skills taught and those assessed through careful coding of trainees' communication encounters and direct feedback.

  5. INCAS: an analytical model to describe displacement cascades

    Energy Technology Data Exchange (ETDEWEB)

    Jumel, Stephanie E-mail: stephanie.jumel@edf.fr; Claude Van-Duysen, Jean E-mail: jean-claude.van-duysen@edf.fr

    2004-07-01

    REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricite de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory.

  6. INCAS: an analytical model to describe displacement cascades

    Science.gov (United States)

    Jumel, Stéphanie; Claude Van-Duysen, Jean

    2004-07-01

    REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricité de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory.

  7. INCAS: an analytical model to describe displacement cascades

    International Nuclear Information System (INIS)

    Jumel, Stephanie; Claude Van-Duysen, Jean

    2004-01-01

    REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricite de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory

  8. Characteristics of the Japanese Diet Described in Epidemiologic Publications: A Qualitative Systematic Review.

    Science.gov (United States)

    Suzuki, Nozomu; Goto, Yoshihito; Ota, Haruka; Kito, Kumiko; Mano, Fumika; Joo, Erina; Ikeda, Kaori; Inagaki, Nobuya; Nakayama, Takeo

    2018-01-01

    International interest in the Japanese diet has grown in recent years. The aim of this systematic review was to evaluate and organize the Japanese diet and dietary characteristics from an epidemiological perspective, mainly focusing on the nutritional and dietary elements. PubMed, Web of Science, Japan Medical Abstracts Society, JDream III, and CiNii databases were searched. The eligibility criteria included research with an epidemiological study design that was either cross-sectional, cohort, or case-control-based that defined the dietary patterns of the Japanese diet using dietary pattern analysis. A total of 39 research articles that described the Japanese diet were included. The data that were extracted included the following: implementing country, location, study design, participant characteristics, key outcomes, methods used in the analysis of dietary patterns, and descriptions of the Japanese diet. As a result of the systematic review analyzing the descriptions of the Japanese diet from 39 selected articles, we were able to aggregate the descriptions into 16 categories from 33 factors. After performing a content analysis using a further aggregation of categories, we found that the top three applicable categories were soybeans/soybean-derived products, seafood, and vegetables; these were followed by rice and miso soup. The Japanese dietary content was found to be diverse based on an examination of epidemiological studies; however, we were able to aggregate the content into 16 categories. The Japanese diet is considered to be a dietary pattern that contains a combination of factors: the dietary staple, side dishes, and soup.

  9. Learning Actions Models: Qualitative Approach

    DEFF Research Database (Denmark)

    Bolander, Thomas; Gierasimczuk, Nina

    2015-01-01

    In dynamic epistemic logic, actions are described using action models. In this paper we introduce a framework for studying learnability of action models from observations. We present first results concerning propositional action models. First we check two basic learnability criteria: finite ident...

  10. Using multistage models to describe radiation-induced leukaemia

    International Nuclear Information System (INIS)

    Little, M.P.; Muirhead, C.R.; Boice, J.D. Jr.; Kleinerman, R.A.

    1995-01-01

    The Armitage-Doll model of carcinogenesis is fitted to data on leukaemia mortality among the Japanese atomic bomb survivors with the DS86 dosimetry and on leukaemia incidence in the International Radiation Study of Cervical Cancer patients. Two different forms of model are fitted: the first postulates up to two radiation-affected stages and the second additionally allows for the presence at birth of a non-trivial population of cells which have already accumulated the first of the mutations leading to malignancy. Among models of the first form, a model with two adjacent radiation-affected stages appears to fit the data better than other models of the first form, including both models with two affected stages in any order and models with only one affected stage. The best fitting model predicts a linear-quadratic dose-response and reductions of relative risk with increasing time after exposure and age at exposure, in agreement with what has previously been observed in the Japanese and cervical cancer data. However, on the whole it does not provide an adequate fit to either dataset. The second form of model appears to provide a rather better fit, but the optimal models have biologically implausible parameters (the number of initiated cells at birth is negative) so that this model must also be regarded as providing an unsatisfactory description of the data. (author)

  11. A new settling velocity model to describe secondary sedimentation.

    Science.gov (United States)

    Ramin, Elham; Wágner, Dorottya S; Yde, Lars; Binning, Philip J; Rasmussen, Michael R; Mikkelsen, Peter Steen; Plósz, Benedek Gy

    2014-12-01

    Secondary settling tanks (SSTs) are the most hydraulically sensitive unit operations in biological wastewater treatment plants. The maximum permissible inflow to the plant depends on the efficiency of SSTs in separating and thickening the activated sludge. The flow conditions and solids distribution in SSTs can be predicted using computational fluid dynamics (CFD) tools. Despite extensive studies on the compression settling behaviour of activated sludge and the development of advanced settling velocity models for use in SST simulations, these models are not often used, due to the challenges associated with their calibration. In this study, we developed a new settling velocity model, including hindered, transient and compression settling, and showed that it can be calibrated to data from a simple, novel settling column experimental set-up using the Bayesian optimization method DREAM(ZS). In addition, correlations between the Herschel-Bulkley rheological model parameters and sludge concentration were identified with data from batch rheological experiments. A 2-D axisymmetric CFD model of a circular SST containing the new settling velocity and rheological model was validated with full-scale measurements. Finally, it was shown that the representation of compression settling in the CFD model can significantly influence the prediction of sludge distribution in the SSTs under dry- and wet-weather flow conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. A new settling velocity model to describe secondary sedimentation

    DEFF Research Database (Denmark)

    Ramin, Elham; Wágner, Dorottya Sarolta; Yde, Lars

    2014-01-01

    Secondary settling tanks (SSTs) are the most hydraulically sensitive unit operations in biological wastewater treatment plants. The maximum permissible inflow to the plant depends on the efficiency of SSTs in separating and thickening the activated sludge. The flow conditions and solids...... distribution in SSTs can be predicted using computational fluid dynamics (CFD) tools. Despite extensive studies on the compression settling behaviour of activated sludge and the development of advanced settling velocity models for use in SST simulations, these models are not often used, due to the challenges...... associated with their calibration. In this study, we developed a new settling velocity model, including hindered, transient and compression settling, and showed that it can be calibrated to data from a simple, novel settling column experimental set-up using the Bayesian optimization method DREAM...

  13. LCM 3.0: A Language for describing Conceptual Models

    NARCIS (Netherlands)

    Feenstra, Remco; Wieringa, Roelf J.

    1993-01-01

    The syntax of the conceptual model specification language LCM is defined. LCM uses equational logic to specify data types and order-sorted dynamic logic to specify objects with identity and mutable state. LCM specifies database transactions as finite sets of atomic object transitions.

  14. A dynamic data based model describing nephropathia epidemica in Belgium

    NARCIS (Netherlands)

    Amirpour Haredasht, S.; Barrios, J.M.; Maes, P.; Verstraeten, W.W.; Clement, J.; Ducoffre, G.; Lagrou, K.; Van Ranst, M.; Coppin, P.; Berckmans, D.; Aerts, J.M.F.G.

    2011-01-01

    ropathia epidemica (NE) is a human infection caused by Puumala virus (PUUV), which is naturally carried and shed by bank voles (Myodes glareolus). Population dynamics and infectious diseases in general, such as NE, have often been modelled with mechanistic SIR (Susceptible, Infective and Remove with

  15. A general modeling framework for describing spatially structured population dynamics

    Science.gov (United States)

    Sample, Christine; Fryxell, John; Bieri, Joanna; Federico, Paula; Earl, Julia; Wiederholt, Ruscena; Mattsson, Brady; Flockhart, Tyler; Nicol, Sam; Diffendorfer, James E.; Thogmartin, Wayne E.; Erickson, Richard A.; Norris, D. Ryan

    2017-01-01

    Variation in movement across time and space fundamentally shapes the abundance and distribution of populations. Although a variety of approaches model structured population dynamics, they are limited to specific types of spatially structured populations and lack a unifying framework. Here, we propose a unified network-based framework sufficiently novel in its flexibility to capture a wide variety of spatiotemporal processes including metapopulations and a range of migratory patterns. It can accommodate different kinds of age structures, forms of population growth, dispersal, nomadism and migration, and alternative life-history strategies. Our objective was to link three general elements common to all spatially structured populations (space, time and movement) under a single mathematical framework. To do this, we adopt a network modeling approach. The spatial structure of a population is represented by a weighted and directed network. Each node and each edge has a set of attributes which vary through time. The dynamics of our network-based population is modeled with discrete time steps. Using both theoretical and real-world examples, we show how common elements recur across species with disparate movement strategies and how they can be combined under a unified mathematical framework. We illustrate how metapopulations, various migratory patterns, and nomadism can be represented with this modeling approach. We also apply our network-based framework to four organisms spanning a wide range of life histories, movement patterns, and carrying capacities. General computer code to implement our framework is provided, which can be applied to almost any spatially structured population. This framework contributes to our theoretical understanding of population dynamics and has practical management applications, including understanding the impact of perturbations on population size, distribution, and movement patterns. By working within a common framework, there is less chance

  16. Describing a Strongly Correlated Model System with Density Functional Theory.

    Science.gov (United States)

    Kong, Jing; Proynov, Emil; Yu, Jianguo; Pachter, Ruth

    2017-07-06

    The linear chain of hydrogen atoms, a basic prototype for the transition from a metal to Mott insulator, is studied with a recent density functional theory model functional for nondynamic and strong correlation. The computed cohesive energy curve for the transition agrees well with accurate literature results. The variation of the electronic structure in this transition is characterized with a density functional descriptor that yields the atomic population of effectively localized electrons. These new methods are also applied to the study of the Peierls dimerization of the stretched even-spaced Mott insulator to a chain of H 2 molecules, a different insulator. The transitions among the two insulating states and the metallic state of the hydrogen chain system are depicted in a semiquantitative phase diagram. Overall, we demonstrate the capability of studying strongly correlated materials with a mean-field model at the fundamental level, in contrast to the general pessimistic view on such a feasibility.

  17. A Biophysical Neural Model To Describe Spatial Visual Attention

    International Nuclear Information System (INIS)

    Hugues, Etienne; Jose, Jorge V.

    2008-01-01

    Visual scenes have enormous spatial and temporal information that are transduced into neural spike trains. Psychophysical experiments indicate that only a small portion of a spatial image is consciously accessible. Electrophysiological experiments in behaving monkeys have revealed a number of modulations of the neural activity in special visual area known as V4, when the animal is paying attention directly towards a particular stimulus location. The nature of the attentional input to V4, however, remains unknown as well as to the mechanisms responsible for these modulations. We use a biophysical neural network model of V4 to address these issues. We first constrain our model to reproduce the experimental results obtained for different external stimulus configurations and without paying attention. To reproduce the known neuronal response variability, we found that the neurons should receive about equal, or balanced, levels of excitatory and inhibitory inputs and whose levels are high as they are in in vivo conditions. Next we consider attentional inputs that can induce and reproduce the observed spiking modulations. We also elucidate the role played by the neural network to generate these modulations

  18. Using concept maps to describe undergraduate students’ mental model in microbiology course

    Science.gov (United States)

    Hamdiyati, Y.; Sudargo, F.; Redjeki, S.; Fitriani, A.

    2018-05-01

    The purpose of this research was to describe students’ mental model in a mental model based-microbiology course using concept map as assessment tool. Respondents were 5th semester of undergraduate students of Biology Education of Universitas Pendidikan Indonesia. The mental modelling instrument used was concept maps. Data were taken on Bacteria sub subject. A concept map rubric was subsequently developed with a maximum score of 4. Quantitative data was converted into a qualitative one to determine mental model level, namely: emergent = score 1, transitional = score 2, close to extended = score 3, and extended = score 4. The results showed that mental model level on bacteria sub subject before the implementation of mental model based-microbiology course was at the transitional level. After implementation of mental model based-microbiology course, mental model was at transitional level, close to extended, and extended. This indicated an increase in the level of students’ mental model after the implementation of mental model based-microbiology course using concept map as assessment tool.

  19. Controller Synthesis using Qualitative Models and Constraints

    OpenAIRE

    Ramamoorthy, Subramanian; Kuipers, Benjamin J

    2004-01-01

    Many engineering systems require the synthesis of global behaviors in nonlinear dynamical systems. Multiple model approaches to control design make it possible to synthesize robust and optimal versions of such global behaviors. We propose a methodology called Qualitative Heterogeneous Control that enables this type of control design. This methodology is based on a separation of concerns between qualitative correctness and quantitative optimization. Qualitative sufficient conditions are derive...

  20. Diagnostic reasoning using qualitative causal models

    International Nuclear Information System (INIS)

    Sudduth, A.L.

    1992-01-01

    The application of expert systems to reasoning problems involving real-time data from plant measurements has been a topic of much research, but few practical systems have been deployed. One obstacle to wider use of expert systems in applications involving real-time data is the lack of adequate knowledge representation methodologies for dynamic processes. Knowledge bases composed mainly of rules have disadvantages when applied to dynamic processes and real-time data. This paper describes a methodology for the development of qualitative causal models that can be used as knowledge bases for reasoning about process dynamic behavior. These models provide a systematic method for knowledge base construction, considerably reducing the engineering effort required. They also offer much better opportunities for verification and validation of the knowledge base, thus increasing the possibility of the application of expert systems to reasoning about mission critical systems. Starting with the Signed Directed Graph (SDG) method that has been successfully applied to describe the behavior of diverse dynamic processes, the paper shows how certain non-physical behaviors that result from abstraction may be eliminated by applying causal constraint to the models. The resulting Extended Signed Directed Graph (ESDG) may then be compiled to produce a model for use in process fault diagnosis. This model based reasoning methodology is used in the MOBIAS system being developed by Duke Power Company under EPRI sponsorship. 15 refs., 4 figs

  1. Qualitative models for space system engineering

    Science.gov (United States)

    Forbus, Kenneth D.

    1990-01-01

    The objectives of this project were: (1) to investigate the implications of qualitative modeling techniques for problems arising in the monitoring, diagnosis, and design of Space Station subsystems and procedures; (2) to identify the issues involved in using qualitative models to enhance and automate engineering functions. These issues include representing operational criteria, fault models, alternate ontologies, and modeling continuous signals at a functional level of description; and (3) to develop a prototype collection of qualitative models for fluid and thermal systems commonly found in Space Station subsystems. Potential applications of qualitative modeling to space-systems engineering, including the notion of intelligent computer-aided engineering are summarized. Emphasis is given to determining which systems of the proposed Space Station provide the most leverage for study, given the current state of the art. Progress on using qualitative models, including development of the molecular collection ontology for reasoning about fluids, the interaction of qualitative and quantitative knowledge in analyzing thermodynamic cycles, and an experiment on building a natural language interface to qualitative reasoning is reported. Finally, some recommendations are made for future research.

  2. Decision making in goverment tenders: A formalized qualitative model

    Directory of Open Access Journals (Sweden)

    Štěpán Veselý

    2012-01-01

    Full Text Available The paper presents a simple formalized qualitative model of government tenders (GTs. Qualitative models use just three values: Positive/Increasing, Zero/Constant and Negative/Decreasing. Such quantifiers of trends are the least information intensive. Qualitative models can be useful, since GT evaluation often includes such goals as e.g. efficiency of public purchasing, and variables as e.g. availability of relevant information or subjectivity of judgment, that are difficult to quantify. Hence, a significant fraction of available information about GTs is not of numerical nature, e.g. if availability of relevant information is decreasing then efficiency of public purchasing is decreasing as well. Such equationless relations are studied in this paper. A qualitative model of the function F(Goals, Variables is developed. The model has four goal functions, eight variables, and 39 equationless relations. The model is solved and seven solutions, i.e. scenarios are obtained. All qualitative states, including first and second qualitative derivatives with respect to time, of all variables are specified for each scenario. Any unsteady state behavior of the GT model is described by its transitional oriented graph. There are eight possible transitions among seven scenarios. No a priori knowledge of qualitative modeling is required on the reader’s part.

  3. A flowing plasma model to describe drift waves in a cylindrical helicon discharge

    International Nuclear Information System (INIS)

    Chang, L.; Hole, M. J.; Corr, C. S.

    2011-01-01

    A two-fluid model developed originally to describe wave oscillations in the vacuum arc centrifuge, a cylindrical, rapidly rotating, low temperature, and confined plasma column, is applied to interpret plasma oscillations in a RF generated linear magnetized plasma [WOMBAT (waves on magnetized beams and turbulence)], with similar density and field strength. Compared to typical centrifuge plasmas, WOMBAT plasmas have slower normalized rotation frequency, lower temperature, and lower axial velocity. Despite these differences, the two-fluid model provides a consistent description of the WOMBAT plasma configuration and yields qualitative agreement between measured and predicted wave oscillation frequencies with axial field strength. In addition, the radial profile of the density perturbation predicted by this model is consistent with the data. Parameter scans show that the dispersion curve is sensitive to the axial field strength and the electron temperature, and the dependence of oscillation frequency with electron temperature matches the experiment. These results consolidate earlier claims that the density and floating potential oscillations are a resistive drift mode, driven by the density gradient. To our knowledge, this is the first detailed physics model of flowing plasmas in the diffusion region away from the RF source. Possible extensions to the model, including temperature nonuniformity and magnetic field oscillations, are also discussed.

  4. Application of a mathematical model to describe the effects of chlorpyrifos on Caenorhabditis elegans development.

    Directory of Open Access Journals (Sweden)

    Windy A Boyd

    2009-09-01

    Full Text Available The nematode Caenorhabditis elegans is being assessed as an alternative model organism as part of an interagency effort to develop better means to test potentially toxic substances. As part of this effort, assays that use the COPAS Biosort flow sorting technology to record optical measurements (time of flight (TOF and extinction (EXT of individual nematodes under various chemical exposure conditions are being developed. A mathematical model has been created that uses Biosort data to quantitatively and qualitatively describe C. elegans growth, and link changes in growth rates to biological events. Chlorpyrifos, an organophosphate pesticide known to cause developmental delays and malformations in mammals, was used as a model toxicant to test the applicability of the growth model for in vivo toxicological testing.L1 larval nematodes were exposed to a range of sub-lethal chlorpyrifos concentrations (0-75 microM and measured every 12 h. In the absence of toxicant, C. elegans matured from L1s to gravid adults by 60 h. A mathematical model was used to estimate nematode size distributions at various times. Mathematical modeling of the distributions allowed the number of measured nematodes and log(EXT and log(TOF growth rates to be estimated. The model revealed three distinct growth phases. The points at which estimated growth rates changed (change points were constant across the ten chlorpyrifos concentrations. Concentration response curves with respect to several model-estimated quantities (numbers of measured nematodes, mean log(TOF and log(EXT, growth rates, and time to reach change points showed a significant decrease in C. elegans growth with increasing chlorpyrifos concentration.Effects of chlorpyrifos on C. elegans growth and development were mathematically modeled. Statistical tests confirmed a significant concentration effect on several model endpoints. This confirmed that chlorpyrifos affects C. elegans development in a concentration dependent

  5. Qualitative models of global warming amplifiers

    NARCIS (Netherlands)

    Milošević, U.; Bredeweg, B.; de Kleer, J.; Forbus, K.D.

    2010-01-01

    There is growing interest from ecological experts to create qualitative models of phenomena for which numerical information is sparse or missing. We present a number of successful models in the field of environmental science, namely, the domain of global warming. The motivation behind the effort is

  6. Patients suffering from rheumatic disease describing own experiences from participating in Basic Body Awareness Group Therapy: A qualitative pilot study.

    Science.gov (United States)

    Olsen, Aarid Liland; Skjaerven, Liv Helvik

    2016-01-01

    Rheumatic diseases have physical and psychological impact on patients' movement and function. Basic Body Awareness Therapy focuses on promoting more functional movement quality in daily life. The purpose of this study was to describe patient experiences from participating in Basic Body Awareness Group Therapy for inpatients with rheumatic disease. A phenomenological design included data collection in two focus group interviews with seven patients. Giorgi's four-step phenomenological method was used for data analysis. Four main themes emerged: (1) "Movement exploration-being guided in movement" described informants' exploration of bodily signals and movement habits; (2) "Movement awareness training in a relational perspective" informants described experiences from being in a group setting; (3) "Movement awareness-integration and insight" described informants' reflections on movement experiences; and (4) "Integrating and practicing new movement habits" informants described how they used their movement experiences in daily life. The study described perspectives in movement learning experienced by patients. The results support the view that contact with the body can help patients exploring and cultivating their own resources for a more functional movement quality. Descriptions of relational movement learning aspects can contribute to our understanding of physiotherapy group design.

  7. A Qualitative Acceleration Model Based on Intervals

    Directory of Open Access Journals (Sweden)

    Ester MARTINEZ-MARTIN

    2013-08-01

    Full Text Available On the way to autonomous service robots, spatial reasoning plays a main role since it properly deals with problems involving uncertainty. In particular, we are interested in knowing people's pose to avoid collisions. With that aim, in this paper, we present a qualitative acceleration model for robotic applications including representation, reasoning and a practical application.

  8. How rural and urban parents describe convenience in the context of school-based influenza vaccination: a qualitative study.

    Science.gov (United States)

    Lind, Candace; Russell, Margaret L; Collins, Ramona; MacDonald, Judy; Frank, Christine J; Davis, Amy E

    2015-01-22

    Seasonal influenza vaccine uptake among school-age children has been low, particularly among rural children, even in jurisdictions in Canada where this immunization is publicly funded. Providing this vaccination at school may be convenient for parents and might contribute to increased vaccine uptake, particularly among rural children. We explore the construct of convenience as an advantage of school based influenza vaccination. We also explore for rural urban differences in this construct. Participants were parents of school-aged children from Alberta, Canada. We qualitatively analyzed focus group data from rural parents using a thematic template that emerged from prior work with urban parents. Both groups of parents had participated in focus groups to explore their perspectives on the acceptability of adding an annual influenza immunization to the immunization program that is currently delivered in Alberta schools. Data from within the theme of 'convenience' from both rural and urban parents were then further explored for sub-themes within convenience. Data were obtained from nine rural and nine urban focus groups. The template of themes that had arisen from prior analysis of the urban data applied to the rural data. Convenience was a third level theme under Advantages. Five fourth level themes emerged from within convenience. Four of the five sub-themes were common to both rural and urban participants: reduction of parental burden to schedule, reduction in parental lost time, decrease in parental stress and increase in physical access points for influenza immunization. The fifth subtheme, increases temporal access to influenza immunization, emerged uniquely from the rural data. Both rural and urban parents perceived that convenience would be an advantage of adding an annual influenza immunization to the vaccinations currently given to Alberta children at school. Improving temporal access to such immunization may be a more relevant aspect of convenience to rural

  9. Qualitative mechanism models and the rationalization of procedures

    Science.gov (United States)

    Farley, Arthur M.

    1989-01-01

    A qualitative, cluster-based approach to the representation of hydraulic systems is described and its potential for generating and explaining procedures is demonstrated. Many ideas are formalized and implemented as part of an interactive, computer-based system. The system allows for designing, displaying, and reasoning about hydraulic systems. The interactive system has an interface consisting of three windows: a design/control window, a cluster window, and a diagnosis/plan window. A qualitative mechanism model for the ORS (Orbital Refueling System) is presented to coordinate with ongoing research on this system being conducted at NASA Ames Research Center.

  10. Review of reactive kinetic models describing reductive dechlorination of chlorinated ethenes in soil and groundwater

    DEFF Research Database (Denmark)

    Chambon, Julie Claire Claudia; Bjerg, Poul Løgstrup; Scheutz, Charlotte

    2013-01-01

    Reductive dechlorination is a major degradation pathway of chlorinated ethenes in anaerobic subsurface environments, and reactive kinetic models describing the degradation process are needed in fate and transport models of these contaminants. However, reductive dechlorination is a complex biologi...

  11. A model describing water and salt migration in concrete during wetting/drying cycles

    NARCIS (Netherlands)

    Arends, T.; Taher, A.; van der Zanden, A.J.J.; Brouwers, H.J.H.; Bilek, V.; Kersner, Z.

    2014-01-01

    In order to predict the life span of concrete structures, models describing the migration of chloride are needed. In this paper, a start is made with a simple, theoretical model describing water and chloride transport in a concrete sample. First, transport of water in concrete is considered with

  12. Qualitative simulation in formal process modelling

    International Nuclear Information System (INIS)

    Sivertsen, Elin R.

    1999-01-01

    In relation to several different research activities at the OECD Halden Reactor Project, the usefulness of formal process models has been identified. Being represented in some appropriate representation language, the purpose of these models is to model process plants and plant automatics in a unified way to allow verification and computer aided design of control strategies. The present report discusses qualitative simulation and the tool QSIM as one approach to formal process models. In particular, the report aims at investigating how recent improvements of the tool facilitate the use of the approach in areas like process system analysis, procedure verification, and control software safety analysis. An important long term goal is to provide a basis for using qualitative reasoning in combination with other techniques to facilitate the treatment of embedded programmable systems in Probabilistic Safety Analysis (PSA). This is motivated from the potential of such a combination in safety analysis based on models comprising both software, hardware, and operator. It is anticipated that the research results from this activity will benefit V and V in a wide variety of applications where formal process models can be utilized. Examples are operator procedures, intelligent decision support systems, and common model repositories (author) (ml)

  13. Endorsement of Models Describing Sexual Response of Men and Women with a Sexual Partner

    DEFF Research Database (Denmark)

    Giraldi, Annamaria; Kristensen, Ellids; Sand, Michael

    2015-01-01

    , erectile dysfunction and dissatisfaction with sexual life were significantly related to endorsement of the Basson model or none of the models (P = 0.01). CONCLUSIONS: No single model of sexual response could describe men's and women's sexual responses. The majority of men and women with no sexual......INTRODUCTION: Several models have been used to describe men's and women's sexual responses. These models have been conceptualized as linear or circular models. The circular models were proposed to describe women's sexual function best. AIM: This study aims to determine whether men and women thought...... that current theoretical models of sexual responses accurately reflected their own sexual experience and to what extent this was influenced by sexual dysfunction. METHODS: A cross-sectional study of a large, broadly sampled, nonclinical population, cohort of Danish men and women. The Female Sexual Function...

  14. A revised multi-Fickian moisture transport model to describe non-Fickian effects in wood

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Damkilde, Lars; Svensson, Staffan

    2007-01-01

    This paper presents a study and a refinement of the sorption rate model in a so-called multi-Fickian or multi-phase model. This type of model describes the complex moisture transport system in wood, which consists of separate water vapor and bound-water diffusion interacting through sorption...... sorption allow a simplification of the system to be modeled by a single Fickian diffusion equation. To determine the response of the system, the sorption rate model is essential. Here the function modeling the moisture-dependent adsorption rate is investigated based on existing experiments on thin wood...

  15. A model based on soil structural aspects describing the fate of genetically modified bacteria in soil

    NARCIS (Netherlands)

    Hoeven, van der N.; Elsas, van J.D.; Heijnen, C.E.

    1996-01-01

    A computer simulation model was developed which describes growth and competition of bacteria in the soil environment. In the model, soil was assumed to contain millions of pores of a few different size classes. An introduced bacterial strain, e.g. a genetically modified micro-organism (GEMMO), was

  16. CLIC Detector Concepts as described in the CDR: Differences between the GEANT4 and Engineering Models

    CERN Document Server

    Elsener, K; Schlatter, D; Siegrist, N

    2011-01-01

    The CLIC_ILD and CLIC_SiD detector concepts as used for the CDR Vol. 2 in 2011 exist both in GEANT4 simulation models and in engineering layout drawings. At this early stage of a conceptual design, there are inevitably differences between these models, which are described in this note.

  17. Numerical model describing the heat transfer between combustion products and ventilation-system duct walls

    International Nuclear Information System (INIS)

    Bolstad, J.W.; Foster, R.D.; Gregory, W.S.

    1983-01-01

    A package of physical models simulating the heat transfer processes occurring between combustion gases and ducts in ventilation systems is described. The purpose of the numerical model is to predict how the combustion gas in a system heats up or cools down as it flows through the ducts in a ventilation system under fire conditions. The model treats a duct with (forced convection) combustion gases flowing on the inside and stagnant ambient air on the outside. The model is composed of five submodels of heat transfer processes along with a numerical solution procedure to evaluate them. Each of these quantities is evaluated independently using standard correlations based on experimental data. The details of the physical assumptions, simplifications, and ranges of applicability of the correlations are described. A typical application of this model to a full-scale fire test is discussed, and model predictions are compared with selected experimental data

  18. Using logic model methods in systematic review synthesis: describing complex pathways in referral management interventions.

    Science.gov (United States)

    Baxter, Susan K; Blank, Lindsay; Woods, Helen Buckley; Payne, Nick; Rimmer, Melanie; Goyder, Elizabeth

    2014-05-10

    There is increasing interest in innovative methods to carry out systematic reviews of complex interventions. Theory-based approaches, such as logic models, have been suggested as a means of providing additional insights beyond that obtained via conventional review methods. This paper reports the use of an innovative method which combines systematic review processes with logic model techniques to synthesise a broad range of literature. The potential value of the model produced was explored with stakeholders. The review identified 295 papers that met the inclusion criteria. The papers consisted of 141 intervention studies and 154 non-intervention quantitative and qualitative articles. A logic model was systematically built from these studies. The model outlines interventions, short term outcomes, moderating and mediating factors and long term demand management outcomes and impacts. Interventions were grouped into typologies of practitioner education, process change, system change, and patient intervention. Short-term outcomes identified that may result from these interventions were changed physician or patient knowledge, beliefs or attitudes and also interventions related to changed doctor-patient interaction. A range of factors which may influence whether these outcomes lead to long term change were detailed. Demand management outcomes and intended impacts included content of referral, rate of referral, and doctor or patient satisfaction. The logic model details evidence and assumptions underpinning the complex pathway from interventions to demand management impact. The method offers a useful addition to systematic review methodologies. PROSPERO registration number: CRD42013004037.

  19. A standard protocol for describing individual-based and agent-based models

    Science.gov (United States)

    Grimm, Volker; Berger, Uta; Bastiansen, Finn; Eliassen, Sigrunn; Ginot, Vincent; Giske, Jarl; Goss-Custard, John; Grand, Tamara; Heinz, Simone K.; Huse, Geir; Huth, Andreas; Jepsen, Jane U.; Jorgensen, Christian; Mooij, Wolf M.; Muller, Birgit; Pe'er, Guy; Piou, Cyril; Railsback, Steven F.; Robbins, Andrew M.; Robbins, Martha M.; Rossmanith, Eva; Ruger, Nadja; Strand, Espen; Souissi, Sami; Stillman, Richard A.; Vabo, Rune; Visser, Ute; DeAngelis, Donald L.

    2006-01-01

    Simulation models that describe autonomous individual organisms (individual based models, IBM) or agents (agent-based models, ABM) have become a widely used tool, not only in ecology, but also in many other disciplines dealing with complex systems made up of autonomous entities. However, there is no standard protocol for describing such simulation models, which can make them difficult to understand and to duplicate. This paper presents a proposed standard protocol, ODD, for describing IBMs and ABMs, developed and tested by 28 modellers who cover a wide range of fields within ecology. This protocol consists of three blocks (Overview, Design concepts, and Details), which are subdivided into seven elements: Purpose, State variables and scales, Process overview and scheduling, Design concepts, Initialization, Input, and Submodels. We explain which aspects of a model should be described in each element, and we present an example to illustrate the protocol in use. In addition, 19 examples are available in an Online Appendix. We consider ODD as a first step for establishing a more detailed common format of the description of IBMs and ABMs. Once initiated, the protocol will hopefully evolve as it becomes used by a sufficiently large proportion of modellers.

  20. A statistical model describing combined irreversible electroporation and electroporation-induced blood-brain barrier disruption.

    Science.gov (United States)

    Sharabi, Shirley; Kos, Bor; Last, David; Guez, David; Daniels, Dianne; Harnof, Sagi; Mardor, Yael; Miklavcic, Damijan

    2016-03-01

    Electroporation-based therapies such as electrochemotherapy (ECT) and irreversible electroporation (IRE) are emerging as promising tools for treatment of tumors. When applied to the brain, electroporation can also induce transient blood-brain-barrier (BBB) disruption in volumes extending beyond IRE, thus enabling efficient drug penetration. The main objective of this study was to develop a statistical model predicting cell death and BBB disruption induced by electroporation. This model can be used for individual treatment planning. Cell death and BBB disruption models were developed based on the Peleg-Fermi model in combination with numerical models of the electric field. The model calculates the electric field thresholds for cell kill and BBB disruption and describes the dependence on the number of treatment pulses. The model was validated using in vivo experimental data consisting of rats brains MRIs post electroporation treatments. Linear regression analysis confirmed that the model described the IRE and BBB disruption volumes as a function of treatment pulses number (r(2) = 0.79; p disruption, the ratio increased with the number of pulses. BBB disruption radii were on average 67% ± 11% larger than IRE volumes. The statistical model can be used to describe the dependence of treatment-effects on the number of pulses independent of the experimental setup.

  1. An algorithm to detect and communicate the differences in computational models describing biological systems.

    Science.gov (United States)

    Scharm, Martin; Wolkenhauer, Olaf; Waltemath, Dagmar

    2016-02-15

    Repositories support the reuse of models and ensure transparency about results in publications linked to those models. With thousands of models available in repositories, such as the BioModels database or the Physiome Model Repository, a framework to track the differences between models and their versions is essential to compare and combine models. Difference detection not only allows users to study the history of models but also helps in the detection of errors and inconsistencies. Existing repositories lack algorithms to track a model's development over time. Focusing on SBML and CellML, we present an algorithm to accurately detect and describe differences between coexisting versions of a model with respect to (i) the models' encoding, (ii) the structure of biological networks and (iii) mathematical expressions. This algorithm is implemented in a comprehensive and open source library called BiVeS. BiVeS helps to identify and characterize changes in computational models and thereby contributes to the documentation of a model's history. Our work facilitates the reuse and extension of existing models and supports collaborative modelling. Finally, it contributes to better reproducibility of modelling results and to the challenge of model provenance. The workflow described in this article is implemented in BiVeS. BiVeS is freely available as source code and binary from sems.uni-rostock.de. The web interface BudHat demonstrates the capabilities of BiVeS at budhat.sems.uni-rostock.de. © The Author 2015. Published by Oxford University Press.

  2. A consilience model to describe N2O production during biological N removal

    DEFF Research Database (Denmark)

    Domingo Felez, Carlos; Smets, Barth F.

    2016-01-01

    Nitrous oxide (N2O), a potent greenhouse gas, is produced during biological nitrogen conversion in wastewater treatment operations. Complex mechanisms underlie N2O production by autotrophic and heterotrophic organisms, which continue to be unravelled. Mathematical models that describe nitric oxide...... (NO) and N2O dynamics have been proposed. Here, a first comprehensive model that considers all relevant NO and N2O production and consumption mechanisms is proposed. The model describes autotrophic NO production by ammonia oxidizing bacteria associated with ammonia oxidation and with nitrite reduction......, followed by NO reduction to N2O. It also considers NO and N2O as intermediates in heterotrophic denitrification in a 4-step model. Three biological NO and N2O production pathways are accounted for, improving the capabilities of existing models while not increasing their complexity. Abiotic contributions...

  3. Describing the processes of propagation and eliminating wildfires with the use of agent models

    Directory of Open Access Journals (Sweden)

    G. A. Dorrer

    2017-10-01

    Full Text Available A new method of describing the processes of propagation and elimination of wildfires on the basis of agent-based modeling is proposed. The main structural units of the creation of such models are the classes of active objects (agents. Agent approach, combined with Geographic Information Systems (GIS can effectively describe the interaction of a large number of participants in the process to combat wildfires: fire spreading, fire crews, mechanization, aerial means and other. In this paper we propose a multi-agent model to predict the spread of wildfire edge and simulate the direct method of extinguishing a ground fire with non-mechanized crews. The model consist with two classes of agents, designated A and B. The burning fire edge is represented as a chain of A-agents, each of which simulates the burning of an elementary portion of vegetation fuel. Fire front movement (moving the A-agent described by the Hamilton-Jacobi equation with using the indicatrises of normal front rate of spread (figurotris. The configuration of the front calculated on basis the algorithm of mobile grids. Agents other type, B-agents, described extinguishing process; they move to the agents of A type and act on them, reducing the combustion intensity to zero. Modeling system presented as two-level coloured nested Petri Net, which describes the agents’ interaction semantics. This model is implemented as a GIS-oriented software system that can be useful both in the fire fighting management as well as in staff training tactics to fighting wildfires. Some examples of modeling decision making on а ground fire extinguishing are presented.

  4. A model to describe potential effects of chemotherapy on critical radiobiological treatments

    International Nuclear Information System (INIS)

    Rodríguez-Pérez, D.; Desco, M.M.; Antoranz, J.C.

    2016-01-01

    Although chemo- and radiotherapy can annihilate tumors on their own. they are also used in coadjuvancy: improving local effects of radiotherapy using chemotherapy as a radiosensit.izer. The effects of radiotherapy are well described by current radiobiological models. The goal of this work is to describe a discrete radiotherapy model, that has been previously used describe high radiation dose response as well as unusual radio-responses of some types of tumors (e.g. prostate cancer), to obtain a model of chemo+radiotherapy that can describe how the outcome of their combination is a more efficient removal of the tumor. Our hypothesis is that, although both treatments haven different mechanisms, both affect similar key points of cell metabolism and regulation, that lead to cellular death. Hence, we will consider a discrete model where chemotherapy may affect a fraction of the same targets destroyed by radiotherapy. Although radiotherapy reaches all cells equally, chemotherapy diffuses through a tumor attaining lower concentration in its center and higher in its surface. With our simulations we study the enhanced effect of combined therapy treatment and how it depends on the tissue critical parameters (the parameters of the lion-extensive radiobiological model), the number of “targets” aimed at by chemotherapy, and the concentration and diffusion rate of the drug inside the tumor. The results show that an equivalent, cliemo-radio-dose can be computed that allows the prediction of the lower radiation dose that causes the same effect than a radio-only treatment. (paper)

  5. A model to describe potential effects of chemotherapy on critical radiobiological treatments

    Science.gov (United States)

    Rodríguez-Pérez, D.; Desco, M. M.; Antoranz, J. C.

    2016-08-01

    Although chemo- and radiotherapy can annihilate tumors on their own. they are also used in coadjuvancy: improving local effects of radiotherapy using chemotherapy as a radiosensit.izer. The effects of radiotherapy are well described by current radiobiological models. The goal of this work is to describe a discrete radiotherapy model, that has been previously used describe high radiation dose response as well as unusual radio-responses of some types of tumors (e.g. prostate cancer), to obtain a model of chemo+radiotherapy that can describe how the outcome of their combination is a more efficient removal of the tumor. Our hypothesis is that, although both treatments haven different mechanisms, both affect similar key points of cell metabolism and regulation, that lead to cellular death. Hence, we will consider a discrete model where chemotherapy may affect a fraction of the same targets destroyed by radiotherapy. Although radiotherapy reaches all cells equally, chemotherapy diffuses through a tumor attaining lower concentration in its center and higher in its surface. With our simulations we study the enhanced effect of combined therapy treatment and how it depends on the tissue critical parameters (the parameters of the lion-extensive radiobiological model), the number of “targets” aimed at by chemotherapy, and the concentration and diffusion rate of the drug inside the tumor. The results show that an equivalent, cliemo-radio-dose can be computed that allows the prediction of the lower radiation dose that causes the same effect than a radio-only treatment.

  6. A two component model describing nucleon structure functions in the low-x region

    Energy Technology Data Exchange (ETDEWEB)

    Bugaev, E.V. [Institute for Nuclear Research of the Russian Academy of Sciences, 7a, 60th October Anniversary prospect, Moscow 117312 (Russian Federation); Mangazeev, B.V. [Irkutsk State University, 1, Karl Marx Street, Irkutsk 664003 (Russian Federation)

    2009-12-15

    A two component model describing the electromagnetic nucleon structure functions in the low-x region, based on generalized vector dominance and color dipole approaches is briefly described. The model operates with the mesons of rho-family having the mass spectrum of the form m{sub n}{sup 2}=m{sub r}ho{sup 2}(1+2n) and takes into account the nondiagonal transitions in meson-nucleon scattering. The special cut-off factors are introduced in the model, to exclude the gamma-qq-bar-V transitions in the case of narrow qq-bar-pairs. For the color dipole part of the model the well known FKS-parameterization is used.

  7. A STRUCTURAL MODEL DESCRIBE CHINESE TRADESMEN ATTITUDES TOWARDS GREEK STUDENTS CONSUMPTION BEHAVIOR

    Directory of Open Access Journals (Sweden)

    Sofia D. ANASTASIADOU

    2012-12-01

    Full Text Available This study tests evaluates 43 Chinese tradesmen opinios describe the main factors that influnce Greek consumers’ behavior. A structural model was constructed to represent the relationship between consumer components. The model was tested for its Convergent and Discriminant Validity. Moreover it was tested for its reliability and construct reliability. The findings from this study may be used by Chinese tradesmen to develop their marketing campains and customers.

  8. Muscle activation described with a differential equation model for large ensembles of locally coupled molecular motors.

    Science.gov (United States)

    Walcott, Sam

    2014-10-01

    Molecular motors, by turning chemical energy into mechanical work, are responsible for active cellular processes. Often groups of these motors work together to perform their biological role. Motors in an ensemble are coupled and exhibit complex emergent behavior. Although large motor ensembles can be modeled with partial differential equations (PDEs) by assuming that molecules function independently of their neighbors, this assumption is violated when motors are coupled locally. It is therefore unclear how to describe the ensemble behavior of the locally coupled motors responsible for biological processes such as calcium-dependent skeletal muscle activation. Here we develop a theory to describe locally coupled motor ensembles and apply the theory to skeletal muscle activation. The central idea is that a muscle filament can be divided into two phases: an active and an inactive phase. Dynamic changes in the relative size of these phases are described by a set of linear ordinary differential equations (ODEs). As the dynamics of the active phase are described by PDEs, muscle activation is governed by a set of coupled ODEs and PDEs, building on previous PDE models. With comparison to Monte Carlo simulations, we demonstrate that the theory captures the behavior of locally coupled ensembles. The theory also plausibly describes and predicts muscle experiments from molecular to whole muscle scales, suggesting that a micro- to macroscale muscle model is within reach.

  9. Robustness of a cross contamination model describing transfer of pathogens during grinding of meat

    DEFF Research Database (Denmark)

    Møller, Cleide Oliveira de Almeida; Sant’Ana, A. S.; Hansen, Solvej Katrine Holm

    2016-01-01

    This study aimed to evaluate a cross contamination model for its capability of describing transfer of Salmonella spp. and L. monocytogenes during grinding of varying sizes and numbers of pieces of meats in two grinder systems. Data from 19 trials were collected. Three evaluation approaches were...

  10. Robustness of a cross contamination model describing transfer of pathogens during grinding of meat

    DEFF Research Database (Denmark)

    Møller, Cleide Oliveira de Almeida; Sant’Ana, A. S.; Hansen, Solvej Katrine Holm

    2016-01-01

    This study aimed to evaluate a cross contamination model for its capability of describing transfer of Salmonella spp. and L. monocytogenes during grinding of varying sizes and numbers of pieces of meats in two grinder systems. Data from 19 trials were collected. Three evaluation approaches were a...... that grinding was influenced by sharpness of grinder knife, specific grinder and grinding temperature....

  11. Development of a Pharmacokinetic Model to Describe the Complex Pharmacokinetics of Pazopanib in Cancer Patients

    NARCIS (Netherlands)

    Yu, Huixin; van Erp, Nielka; Bins, Sander; Mathijssen, Ron H J; Schellens, Jan H M; Beijnen, Jos H.; Steeghs, Neeltje; Huitema, Alwin D R

    Background and Objective: Pazopanib is a multi-targeted anticancer tyrosine kinase inhibitor. This study was conducted to develop a population pharmacokinetic (popPK) model describing the complex pharmacokinetics of pazopanib in cancer patients. Methods: Pharmacokinetic data were available from 96

  12. Development of a Pharmacokinetic Model to Describe the Complex Pharmacokinetics of Pazopanib in Cancer Patients

    NARCIS (Netherlands)

    Yu, H.; Erp, N. van; Bins, S.; Mathijssen, R.H.; Schellens, J.H.; Beijnen, J.H.; Steeghs, N.; Huitema, A.D.

    2017-01-01

    BACKGROUND AND OBJECTIVE: Pazopanib is a multi-targeted anticancer tyrosine kinase inhibitor. This study was conducted to develop a population pharmacokinetic (popPK) model describing the complex pharmacokinetics of pazopanib in cancer patients. METHODS: Pharmacokinetic data were available from 96

  13. Structural Models Describing Placebo Treatment Effects in Schizophrenia and Other Neuropsychiatric Disorders

    NARCIS (Netherlands)

    Reddy, Venkatesh Pilla; Kozielska, Magdalena; Johnson, Martin; Vermeulen, An; de Greef, Rik; Liu, Jing; Groothuis, Geny M. M.; Danhof, Meindert; Proost, Johannes H.

    2011-01-01

    Large variation in placebo response within and among clinical trials can substantially affect conclusions about the efficacy of new medications in psychiatry. Developing a robust placebo model to describe the placebo response is important to facilitate quantification of drug effects, and eventually

  14. Early Childhood Teacher Preparation: A Tale of Authors and Multimedia, A Model of Technology Integration Described.

    Science.gov (United States)

    Wetzel, Keith; McLean, S. V.

    1997-01-01

    Describes collaboration of two teacher educators, one in early childhood language arts and one in computers in education. Discusses advantages and disadvantages and extensions of this model, including how a college-wide survey revealed that students in teamed courses are better prepared to teach and learn with technology. (DR)

  15. Describing Growth Pattern of Bali Cows Using Non-linear Regression Models

    Directory of Open Access Journals (Sweden)

    Mohd. Hafiz A.W

    2016-12-01

    Full Text Available The objective of this study was to evaluate the best fit non-linear regression model to describe the growth pattern of Bali cows. Estimates of asymptotic mature weight, rate of maturing and constant of integration were derived from Brody, von Bertalanffy, Gompertz and Logistic models which were fitted to cross-sectional data of body weight taken from 74 Bali cows raised in MARDI Research Station Muadzam Shah Pahang. Coefficient of determination (R2 and residual mean squares (MSE were used to determine the best fit model in describing the growth pattern of Bali cows. Von Bertalanffy model was the best model among the four growth functions evaluated to determine the mature weight of Bali cattle as shown by the highest R2 and lowest MSE values (0.973 and 601.9, respectively, followed by Gompertz (0.972 and 621.2, respectively, Logistic (0.971 and 648.4, respectively and Brody (0.932 and 660.5, respectively models. The correlation between rate of maturing and mature weight was found to be negative in the range of -0.170 to -0.929 for all models, indicating that animals of heavier mature weight had lower rate of maturing. The use of non-linear model could summarize the weight-age relationship into several biologically interpreted parameters compared to the entire lifespan weight-age data points that are difficult and time consuming to interpret.

  16. Comparison of six different models describing survival of mammalian cells after irradiation

    International Nuclear Information System (INIS)

    Sontag, W.

    1990-01-01

    Six different cell-survival models have been compared. All models are based on the similar assumption that irradiated cells are able to exist in one of three states. S A is the state of a totally repaired cell, in state S C the cell contains lethal lesions and in state S b the cell contains potentially lethal lesions i.e. those which either can be repaired or converted into lethal lesions. The differences between the six models lie in the different mathematical relationships between the three states. To test the six models, six different sets of experimental data were used which describe cell survival at different repair times after irradiation with sparsely ionizing irradiation. In order to compare the models, a goodness-of-fit function was used. The differences between the six models were tested by use of the nonparametric Mann-Whitney two sample test. Based on the 95% confidence limit, this required separation into three groups. (orig.)

  17. Recruiting Transcultural Qualitative Research Participants: A Conceptual Model

    Directory of Open Access Journals (Sweden)

    Phyllis Eide

    2005-06-01

    Full Text Available Working with diverse populations poses many challenges to the qualitative researcher who is a member of the dominant culture. Traditional methods of recruitment and selection (such as flyers and advertisements are often unproductive, leading to missed contributions from potential participants who were not recruited and researcher frustration. In this article, the authors explore recruitment issues related to the concept of personal knowing based on experiences with Aboriginal Hawai'ian and Micronesian populations, wherein knowing and being known are crucial to successful recruitment of participants. They present a conceptual model that incorporates key concepts of knowing the other, cultural context, and trust to guide other qualitative transcultural researchers. They also describe challenges, implications, and concrete suggestions for recruitment of participants.

  18. New Model to describe the interaction of slow neutrons with solid deuterium

    International Nuclear Information System (INIS)

    Granada, J.R

    2009-01-01

    A new scattering kernel to describe the interaction of slow neutrons with solid Deuterium was developed. The main characteristics of that system are contained in the formalism, including the lattice s density of states, the Young-Koppel quantum treatment of the rotations, and the internal molecular vibrations. The elastic processes involving coherent and incoherent contributions are fully described, as well as the spin-correlation effects. The results from the new model are compared with the best available experimental data, showing very good agreement. [es

  19. Regularization of a massless dirac model to describe anomalous electromagnetic response of Weyl semimetals

    International Nuclear Information System (INIS)

    Takane, Yoshitake

    2016-01-01

    An unbounded massless Dirac model with two nondegenerate Dirac cones is the simplest model for Weyl semimetals, which show the anomalous electromagnetic response of chiral magnetic effect (CME) and anomalous Hall effect (AHE). However, if this model is naively used to analyze the electromagnetic response within a linear response theory, it gives the result apparently inconsistent with the persuasive prediction based on a lattice model. We show that this serious difficulty is related to the breaking of current conservation in the Dirac model due to quantum anomaly and can be removed if current and charge operators are redefined to include the contribution from the anomaly. We demonstrate that the CME as well as the AHE can be properly described using newly defined operators, and clarify that the CME is determined by the competition between the contribution from the anomaly and that from low-energy electrons. (author)

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

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. “I feel so stupid because I can’t give a proper answer…” How older adults describe chronic pain: a qualitative study

    Directory of Open Access Journals (Sweden)

    Clarke Amanda

    2012-12-01

    Full Text Available Abstract Background Over 50% of older adults experience chronic pain. Poorly managed pain threatens independent functioning, limits social activities and detrimentally affects emotional wellbeing. Yet, chronic pain is not fully understood from older adults’ perspectives; subsequently, pain management in later life is not necessarily based on their priorities or needs. This paper reports a qualitative exploration of older adults’ accounts of living with chronic pain, focusing on how they describe pain, with a view to informing approaches to its assessment. Methods Cognitively intact men and women aged over sixty-five who lived in the community opted into the study through responding to advertisements in the media and via contacts with groups and organisations in North-East Scotland. Interviews were transcribed and thematically analysed using a framework approach. Results Qualitative individual interviews and one group interview were undertaken with 23 older adults. Following analysis, the following main themes emerged: diversity in conceptualising pain using a simple numerical score; personalising the meaning of pain by way of stories, similes and metaphors; and, contextualising pain in relation to its impact on activities. Conclusions The importance of attending to individuals’ stories as a meaningful way of describing pain for older adults is highlighted, suggesting that a narrative approach, as recommended and researched in other areas of medicine, may usefully be applied in pain assessment for older adults. Along with the judicious use of numerical tools, this requires innovative methods to elicit verbal accounts, such as using similes and metaphors to help older adults describe and discuss their experience, and contextualising the effects of pain on activities that are important to them.

  2. “I feel so stupid because I can’t give a proper answer…” How older adults describe chronic pain: a qualitative study

    Science.gov (United States)

    2012-01-01

    Background Over 50% of older adults experience chronic pain. Poorly managed pain threatens independent functioning, limits social activities and detrimentally affects emotional wellbeing. Yet, chronic pain is not fully understood from older adults’ perspectives; subsequently, pain management in later life is not necessarily based on their priorities or needs. This paper reports a qualitative exploration of older adults’ accounts of living with chronic pain, focusing on how they describe pain, with a view to informing approaches to its assessment. Methods Cognitively intact men and women aged over sixty-five who lived in the community opted into the study through responding to advertisements in the media and via contacts with groups and organisations in North-East Scotland. Interviews were transcribed and thematically analysed using a framework approach. Results Qualitative individual interviews and one group interview were undertaken with 23 older adults. Following analysis, the following main themes emerged: diversity in conceptualising pain using a simple numerical score; personalising the meaning of pain by way of stories, similes and metaphors; and, contextualising pain in relation to its impact on activities. Conclusions The importance of attending to individuals’ stories as a meaningful way of describing pain for older adults is highlighted, suggesting that a narrative approach, as recommended and researched in other areas of medicine, may usefully be applied in pain assessment for older adults. Along with the judicious use of numerical tools, this requires innovative methods to elicit verbal accounts, such as using similes and metaphors to help older adults describe and discuss their experience, and contextualising the effects of pain on activities that are important to them. PMID:23276327

  3. "I feel so stupid because I can't give a proper answer…" How older adults describe chronic pain: a qualitative study.

    Science.gov (United States)

    Clarke, Amanda; Anthony, Geraldine; Gray, Denise; Jones, Derek; McNamee, Paul; Schofield, Patricia; Smith, Blair H; Martin, Denis

    2012-12-31

    Over 50% of older adults experience chronic pain. Poorly managed pain threatens independent functioning, limits social activities and detrimentally affects emotional wellbeing. Yet, chronic pain is not fully understood from older adults' perspectives; subsequently, pain management in later life is not necessarily based on their priorities or needs. This paper reports a qualitative exploration of older adults' accounts of living with chronic pain, focusing on how they describe pain, with a view to informing approaches to its assessment. Cognitively intact men and women aged over sixty-five who lived in the community opted into the study through responding to advertisements in the media and via contacts with groups and organisations in North-East Scotland. Interviews were transcribed and thematically analysed using a framework approach. Qualitative individual interviews and one group interview were undertaken with 23 older adults. Following analysis, the following main themes emerged: diversity in conceptualising pain using a simple numerical score; personalising the meaning of pain by way of stories, similes and metaphors; and, contextualising pain in relation to its impact on activities. The importance of attending to individuals' stories as a meaningful way of describing pain for older adults is highlighted, suggesting that a narrative approach, as recommended and researched in other areas of medicine, may usefully be applied in pain assessment for older adults. Along with the judicious use of numerical tools, this requires innovative methods to elicit verbal accounts, such as using similes and metaphors to help older adults describe and discuss their experience, and contextualising the effects of pain on activities that are important to them.

  4. Describing the clinical reasoning process: application of a model of enablement to a pediatric case.

    Science.gov (United States)

    Furze, Jennifer; Nelson, Kelly; O'Hare, Megan; Ortner, Amanda; Threlkeld, A Joseph; Jensen, Gail M

    2013-04-01

    Clinical reasoning is a core tenet of physical therapy practice leading to optimal patient care. The purpose of this case was to describe the outcomes, subjective experience, and reflective clinical reasoning process for a child with cerebral palsy using the International Classification of Functioning, Disability, and Health (ICF) model. Application of the ICF framework to a 9-year-old boy with spastic triplegic cerebral palsy was utilized to capture the interwoven factors present in this case. Interventions in the pool occurred twice weekly for 1 h over a 10-week period. Immediately post and 4 months post-intervention, the child made functional and meaningful gains. The family unit also developed an enjoyment of exercising together. Each individual family member described psychological, emotional, or physical health improvements. Reflection using the ICF model as a framework to discuss clinical reasoning can highlight important factors contributing to effective patient management.

  5. Living with idiopathic basal ganglia calcification 3: a qualitative study describing the lives and illness of people diagnosed with a rare neurological disease.

    Science.gov (United States)

    Takeuchi, Tomiko; Muraoka, Koko; Yamada, Megumi; Nishio, Yuri; Hozumi, Isao

    2016-01-01

    Idiopathic basal ganglia calcification (IBGC) is a rare, intractable disease with unknown etiology. IBGC3 is a familial genetic disease defined by genetic mutations in the major causative gene ( SLC20A2 ). People with IBGC3 experience distress from the uncommon nature of their illness and uncertainty about treatment and prognoses. The present study aimed to describe the lives and illness of people with IBGC3. Participants were recruited from patients aged 20 years or older enrolled in a genetic study, who were diagnosed with IBGC3 and wanted to share their experiences. In-depth semi-structured interviews were conducted with six participants. Interviews were conducted between December 2012 and February 2014, and were recorded and transcribed verbatim. Qualitative data analysis was performed to identify categories and subcategories. Efforts were made to ensure the credibility, transferability, dependability, conformability, and validity of the data. Six thematic categories, 17 subcategories, and 143 codes emerged. The six categories were: (1) Frustration and anxiety with progression of symptoms without a diagnosis; (2) Confusion about diagnosis with an unfamiliar disease; (3) Emotional distress caused by a genetic disease; (4) Passive attitude toward life, being extra careful; (5) Taking charge of life, becoming active and engaged; and (6) Requests for healthcare. The qualitative data analysis indicated a need for genetic counseling, access to disease information, establishment of peer and family support systems, mental health services, and improvement in early intervention and treatment for the disease.

  6. Development and Application of a Category System to Describe Pre-Service Science Teachers' Activities in the Process of Scientific Modelling

    Science.gov (United States)

    Krell, Moritz; Walzer, Christine; Hergert, Susann; Krüger, Dirk

    2017-09-01

    As part of their professional competencies, science teachers need an elaborate meta-modelling knowledge as well as modelling skills in order to guide and monitor modelling practices of their students. However, qualitative studies about (pre-service) science teachers' modelling practices are rare. This study provides a category system which is suitable to analyse and to describe pre-service science teachers' modelling activities and to infer modelling strategies. The category system was developed based on theoretical considerations and was inductively refined within the methodological frame of qualitative content analysis. For the inductive refinement, modelling practices of pre-service teachers (n = 4) have been video-taped and analysed. In this study, one case was selected to demonstrate the application of the category system to infer modelling strategies. The contribution of this study for science education research and science teacher education is discussed.

  7. Development of zircaloy deformation model to describe the zircaloy-4 cladding tube during accidents

    International Nuclear Information System (INIS)

    Raff, S.

    1978-01-01

    The development of a high-temperature deformation model for Zircaloy-4 cans is primarily based on numerous well-parametrized tensile tests to get the material behaviour including statistical variance. It is shown that plastic deformation may be described by a power creep law, the coefficients of which show strong dependence on temperature in the relevant temperature region. These coefficients have been determined. A model based on these coefficients has been established which, apart from best estimate deformation, gives upper and lower bounds of possible deformation. The model derived from isothermal uniaxial tests is being verified against isothermal and transient tube burst tests. The influence of preoxidation and increased oxygen concentration during deformation is modeled on the basis of the pseudobinary Zircaloy-oxygen phase diagram. (author)

  8. Calibration and validation of a model describing complete autotrophic nitrogen removal in a granular SBR system

    DEFF Research Database (Denmark)

    Vangsgaard, Anna Katrine; Mutlu, Ayten Gizem; Gernaey, Krist

    2013-01-01

    BACKGROUND: A validated model describing the nitritation-anammox process in a granular sequencing batch reactor (SBR) system is an important tool for: a) design of future experiments and b) prediction of process performance during optimization, while applying process control, or during system scale......-up. RESULTS: A model was calibrated using a step-wise procedure customized for the specific needs of the system. The important steps in the procedure were initialization, steady-state and dynamic calibration, and validation. A fast and effective initialization approach was developed to approximate pseudo...... screening of the parameter space proposed by Sin et al. (2008) - to find the best fit of the model to dynamic data. Finally, the calibrated model was validated with an independent data set. CONCLUSION: The presented calibration procedure is the first customized procedure for this type of system...

  9. An empirical model describing the postnatal growth of organs in ICRP reference humans: Pt. 1

    International Nuclear Information System (INIS)

    Walker, J.T.

    1991-01-01

    An empirical model is presented for describing the postnatal mass growth of lungs in ICRP reference humans. A combined exponential and logistic function containing six parameters is fitted to ICRP 23 lung data using a weighted non-linear least squares technique. The results indicate that the model delineates the data well. Further analysis shows that reference male lungs attain a higher pubertal peak velocity (PPV) and adult mass size than female lungs, although the latter reach their PPV and adult mass size first. Furthermore, the model shows that lung growth rates in infants are two to three orders of magnitude higher than those in mature adults. This finding is important because of the possible association between higher radiation risks in infants' organs that have faster cell turnover rates compared to mature adult organs. The significance of the model for ICRP dosimetric purposes will be discussed. (author)

  10. A relativistic gauge model describing N particles bound by harmonic forces

    International Nuclear Information System (INIS)

    Filippov, A.T.

    1987-01-01

    Application of the principle of gauging to linear canonical symmetries of simplest/rudimentary/bilinear lagrangians is shown to produce a relativistic version of the Lagrangian describing N particles bound by harmonic forces. For pairwise coupled identical particles the gauge group is T 1 xU 1 , xSU N-1 . A model for the relativistic discrete string (a chain of N particles) is also discussed. All these gauge theoried of particles can be quantized by standard methods

  11. Composite model describing the excitation and de-excitation of nitrogen by an electron beam

    International Nuclear Information System (INIS)

    Kassem, A.E.; Hickman, R.S.

    1975-01-01

    Based on recent studies, the effect of re-excited ions in the emission of electron beam induced fluorescence in nitrogen has been estimated. These effects are included in the formulation of a composite model describing the excitation and de-excitation of nitrogen by an electron beam. The shortcomings of previous models, namely the dependence of the measured temperature on true gas temperature as well as the gas density, are almost completely eliminated in the range of temperatures and densities covered by the available data. (auth)

  12. Validation of mathematical models to describe fluid dynamics of a cold riser by gamma ray attenuation

    International Nuclear Information System (INIS)

    Melo, Ana Cristina Bezerra Azedo de

    2004-12-01

    The fluid dynamic behavior of a riser in a cold type FCC model was investigated by means of catalyst concentration distribution measured with gamma attenuation and simulated with a mathematical model. In the riser of the cold model, MEF, 0,032 m in diameter, 2,30 m in length the fluidized bed, whose components are air and FCC catalyst, circulates. The MEF is operated by automatic control and instruments for measuring fluid dynamic variables. An axial catalyst concentration distribution was measured using an Am-241 gamma source and a NaI detector coupled to a multichannel provided with a software for data acquisition and evaluation. The MEF was adapted for a fluid dynamic model validation which describes the flow in the riser, for example, by introducing an injector for controlling the solid flow in circulation. Mathematical models were selected from literature, analyzed and tested to simulate the fluid dynamic of the riser. A methodology for validating fluid dynamic models was studied and implemented. The stages of the work were developed according to the validation methodology, such as data planning experiments, study of the equations which describe the fluidodynamic, computational solvers application and comparison with experimental data. Operational sequences were carried out keeping the MEF conditions for measuring catalyst concentration and simultaneously measuring the fluid dynamic variables, velocity of the components and pressure drop in the riser. Following this, simulated and experimental values were compared and statistical data treatment done, aiming at the required precision to validate the fluid dynamic model. The comparison tests between experimental and simulated data were carried out under validation criteria. The fluid dynamic behavior of the riser was analyzed and the results and the agreement with literature were discussed. The adopt model was validated under the MEF operational conditions, for a 3 to 6 m/s gas velocity in the riser and a slip

  13. Suitability of parametric models to describe the hydraulic properties of an unsaturated coarse sand and gravel

    Science.gov (United States)

    Mace, Andy; Rudolph, David L.; Kachanoski , R. Gary

    1998-01-01

    The performance of parametric models used to describe soil water retention (SWR) properties and predict unsaturated hydraulic conductivity (K) as a function of volumetric water content (θ) is examined using SWR and K(θ) data for coarse sand and gravel sediments. Six 70 cm long, 10 cm diameter cores of glacial outwash were instrumented at eight depths with porous cup ten-siometers and time domain reflectometry probes to measure soil water pressure head (h) and θ, respectively, for seven unsaturated and one saturated steady-state flow conditions. Forty-two θ(h) and K(θ) relationships were measured from the infiltration tests on the cores. Of the four SWR models compared in the analysis, the van Genuchten (1980) equation with parameters m and n restricted according to the Mualem (m = 1 - 1/n) criterion is best suited to describe the θ(h) relationships. The accuracy of two models that predict K(θ) using parameter values derived from the SWR models was also evaluated. The model developed by van Genuchten (1980) based on the theoretical expression of Mualem (1976) predicted K(θ) more accurately than the van Genuchten (1980) model based on the theory of Burdine (1953). A sensitivity analysis shows that more accurate predictions of K(θ) are achieved using SWR model parameters derived with residual water content (θr) specified according to independent measurements of θ at values of h where θ/h ∼ 0 rather than model-fit θr values. The accuracy of the model K(θ) function improves markedly when at least one value of unsaturated K is used to scale the K(θ) function predicted using the saturated K. The results of this investigation indicate that the hydraulic properties of coarse-grained sediments can be accurately described using the parametric models. In addition, data collection efforts should focus on measuring at least one value of unsaturated hydraulic conductivity and as complete a set of SWR data as possible, particularly in the dry range.

  14. A metallic solution model with adjustable parameter for describing ternary thermodynamic properties from its binary constituents

    International Nuclear Information System (INIS)

    Fang Zheng; Qiu Guanzhou

    2007-01-01

    A metallic solution model with adjustable parameter k has been developed to predict thermodynamic properties of ternary systems from those of its constituent three binaries. In the present model, the excess Gibbs free energy for a ternary mixture is expressed as a weighted probability sum of those of binaries and the k value is determined based on an assumption that the ternary interaction generally strengthens the mixing effects for metallic solutions with weak interaction, making the Gibbs free energy of mixing of the ternary system more negative than that before considering the interaction. This point is never considered in the models currently reported, where the only difference in a geometrical definition of molar values of components is considered that do not involve thermodynamic principles but are completely empirical. The current model describes the results of experiments very well, and by adjusting the k value also agrees with those from models used widely in the literature. Three ternary systems, Mg-Cu-Ni, Zn-In-Cd, and Cd-Bi-Pb are recalculated to demonstrate the method of determining k and the precision of the model. The results of the calculations, especially those in Mg-Cu-Ni system, are better than those predicted by the current models in the literature

  15. A model describing intra-granular fission gas behaviour in oxide fuel for advanced engineering tools

    Science.gov (United States)

    Pizzocri, D.; Pastore, G.; Barani, T.; Magni, A.; Luzzi, L.; Van Uffelen, P.; Pitts, S. A.; Alfonsi, A.; Hales, J. D.

    2018-04-01

    The description of intra-granular fission gas behaviour is a fundamental part of any model for the prediction of fission gas release and swelling in nuclear fuel. In this work we present a model describing the evolution of intra-granular fission gas bubbles in terms of bubble number density and average size, coupled to gas release to grain boundaries. The model considers the fundamental processes of single gas atom diffusion, gas bubble nucleation, re-solution and gas atom trapping at bubbles. The model is derived from a detailed cluster dynamics formulation, yet it consists of only three differential equations in its final form; hence, it can be efficiently applied in engineering fuel performance codes while retaining a physical basis. We discuss improvements relative to previous single-size models for intra-granular bubble evolution. We validate the model against experimental data, both in terms of bubble number density and average bubble radius. Lastly, we perform an uncertainty and sensitivity analysis by propagating the uncertainties in the parameters to model results.

  16. How Qualitative Methods Can be Used to Inform Model Development.

    Science.gov (United States)

    Husbands, Samantha; Jowett, Susan; Barton, Pelham; Coast, Joanna

    2017-06-01

    Decision-analytic models play a key role in informing healthcare resource allocation decisions. However, there are ongoing concerns with the credibility of models. Modelling methods guidance can encourage good practice within model development, but its value is dependent on its ability to address the areas that modellers find most challenging. Further, it is important that modelling methods and related guidance are continually updated in light of any new approaches that could potentially enhance model credibility. The objective of this article was to highlight the ways in which qualitative methods have been used and recommended to inform decision-analytic model development and enhance modelling practices. With reference to the literature, the article discusses two key ways in which qualitative methods can be, and have been, applied. The first approach involves using qualitative methods to understand and inform general and future processes of model development, and the second, using qualitative techniques to directly inform the development of individual models. The literature suggests that qualitative methods can improve the validity and credibility of modelling processes by providing a means to understand existing modelling approaches that identifies where problems are occurring and further guidance is needed. It can also be applied within model development to facilitate the input of experts to structural development. We recommend that current and future model development would benefit from the greater integration of qualitative methods, specifically by studying 'real' modelling processes, and by developing recommendations around how qualitative methods can be adopted within everyday modelling practice.

  17. A bottom-up model to describe consumers’ preferences towards late season peaches

    Energy Technology Data Exchange (ETDEWEB)

    Groot, E.; Albisu, L.M.

    2015-07-01

    Peaches are consumed in Mediterranean countries since ancient times. Nowadays there are few areas in Europe that produce peaches with Protected Designation of Origin (PDO), and the Calanda area is one of them. The aim of this work is to describe consumers’ preferences towards late season PDO Calanda peaches in the city of Zaragoza, Spain, by a bottom-up model. The bottom-up model proves greater amount of information than top-down models. In this approach it is estimated one utility function per consumer. Thus, it is not necessary to make assumptions about preference distributions and correlations across respondents. It was observed that preference distributions were neither normal nor independently distributed. If those preferences were estimated by top-down models, conclusions would be biased. This paper also explores a new way to describe preferences through individual utility functions. Results show that the largest behavioural group gathered origin sensitive consumers. Their utility increased if the peaches were produced in the Calanda area and, especially, when peaches had the PDO Calanda brand. In sequence, the second most valuable attribute for consumers was the price. Peach size and packaging were not so important on purchase choice decision. Nevertheless, it is advisable to avoid trading smallest size peaches (weighting around 160 g/fruit). Traders also have to be careful by using active packaging. It was found that a group of consumers disliked this kind of product, probably, because they perceived it as less natural. (Author)

  18. An extended car-following model to describe connected traffic dynamics under cyberattacks

    Science.gov (United States)

    Wang, Pengcheng; Yu, Guizhen; Wu, Xinkai; Qin, Hongmao; Wang, Yunpeng

    2018-04-01

    In this paper, the impacts of the potential cyberattacks on vehicles are modeled through an extended car-following model. To better understand the mechanism of traffic disturbance under cyberattacks, the linear and nonlinear stability analysis are conducted respectively. Particularly, linear stability analysis is performed to obtain different neutral stability conditions with various parameters; and nonlinear stability analysis is carried out by using reductive perturbation method to derive the soliton solution of the modified Korteweg de Vries equation (mKdV) near the critical point, which is used to draw coexisting stability lines. Furthermore, by applying linear and nonlinear stability analysis, traffic flow state can be divided into three states, i.e., stable, metastable and unstable states which are useful to describe shockwave dynamics and driving behaviors under cyberattacks. The theoretical results show that the proposed car-following model is capable of successfully describing the car-following behavior of connected vehicles with cyberattacks. Finally, numerical simulation using real values has confirmed the validity of theoretical analysis. The results further demonstrate our model can be used to help avoid collisions and relieve traffic congestion with cybersecurity threats.

  19. Development of a model describing virus removal process in an activated sludge basin

    Energy Technology Data Exchange (ETDEWEB)

    Kim, T.; Shiragami, N. Unno, H. [Tokyo Institute of Technology, Tokyo (Japan)

    1995-06-20

    The virus removal process from the liquid phase in an activated sludge basin possibly consists of physicochemical processes, such as adsorption onto sludge flocs, biological processes such as microbial predating and inactivation by virucidal components excreted by microbes. To describe properly the virus behavior in an activated sludge basin, a simple model is proposed based on the experimental data obtained using a poliovirus type 1. A three-compartments model, which include the virus in the liquid phase and in the peripheral and inner regions of sludge flocs is employed. By using the model, the Virus removal process was successfully simulated to highlight the implication of its distribution in the activated sludge basin. 17 refs., 8 figs.

  20. Digital Materials - Evaluation of the Possibilities of using Selected Hyperelastic Models to Describe Constitutive Relations

    Science.gov (United States)

    Mańkowski, J.; Lipnicki, J.

    2017-08-01

    The authors tried to identify the parameters of numerical models of digital materials, which are a kind of composite resulting from the manufacture of the product in 3D printers. With the arrangement of several heads of the printer, the new material can result from mixing of materials with radically different properties, during the process of producing single layer of the product. The new material has properties dependent on the base materials properties and their proportions. Digital materials tensile characteristics are often non-linear and qualify to be described by hyperelastic materials models. The identification was conducted based on the results of tensile tests models, its various degrees coefficients of the polynomials to various degrees coefficients of the polynomials. The Drucker's stability criterion was also examined. Fourteen different materials were analyzed.

  1. Digital Materials – Evaluation of the Possibilities of using Selected Hyperelastic Models to Describe Constitutive Relations

    Directory of Open Access Journals (Sweden)

    Mańkowski J.

    2017-08-01

    Full Text Available The authors tried to identify the parameters of numerical models of digital materials, which are a kind of composite resulting from the manufacture of the product in 3D printers. With the arrangement of several heads of the printer, the new material can result from mixing of materials with radically different properties, during the process of producing single layer of the product. The new material has properties dependent on the base materials properties and their proportions. Digital materials tensile characteristics are often non-linear and qualify to be described by hyperelastic materials models. The identification was conducted based on the results of tensile tests models, its various degrees coefficients of the polynomials to various degrees coefficients of the polynomials. The Drucker’s stability criterion was also examined. Fourteen different materials were analyzed.

  2. Ordinal regression models to describe tourist satisfaction with Sintra's world heritage

    Science.gov (United States)

    Mouriño, Helena

    2013-10-01

    In Tourism Research, ordinal regression models are becoming a very powerful tool in modelling the relationship between an ordinal response variable and a set of explanatory variables. In August and September 2010, we conducted a pioneering Tourist Survey in Sintra, Portugal. The data were obtained by face-to-face interviews at the entrances of the Palaces and Parks of Sintra. The work developed in this paper focus on two main points: tourists' perception of the entrance fees; overall level of satisfaction with this heritage site. For attaining these goals, ordinal regression models were developed. We concluded that tourist's nationality was the only significant variable to describe the perception of the admission fees. Also, Sintra's image among tourists depends not only on their nationality, but also on previous knowledge about Sintra's World Heritage status.

  3. Computational Models Describing Possible Mechanisms for Generation of Excessive Beta Oscillations in Parkinson's Disease.

    Directory of Open Access Journals (Sweden)

    Alex Pavlides

    2015-12-01

    Full Text Available In Parkinson's disease, an increase in beta oscillations within the basal ganglia nuclei has been shown to be associated with difficulty in movement initiation. An important role in the generation of these oscillations is thought to be played by the motor cortex and by a network composed of the subthalamic nucleus (STN and the external segment of globus pallidus (GPe. Several alternative models have been proposed to describe the mechanisms for generation of the Parkinsonian beta oscillations. However, a recent experimental study of Tachibana and colleagues yielded results which are challenging for all published computational models of beta generation. That study investigated how the presence of beta oscillations in a primate model of Parkinson's disease is affected by blocking different connections of the STN-GPe circuit. Due to a large number of experimental conditions, the study provides strong constraints that any mechanistic model of beta generation should satisfy. In this paper we present two models consistent with the data of Tachibana et al. The first model assumes that Parkinsonian beta oscillation are generated in the cortex and the STN-GPe circuits resonates at this frequency. The second model additionally assumes that the feedback from STN-GPe circuit to cortex is important for maintaining the oscillations in the network. Predictions are made about experimental evidence that is required to differentiate between the two models, both of which are able to reproduce firing rates, oscillation frequency and effects of lesions carried out by Tachibana and colleagues. Furthermore, an analysis of the models reveals how the amplitude and frequency of the generated oscillations depend on parameters.

  4. Development of a geometric uncertainty model describing the accuracy of position-sensitive, coincidence neutron detection

    Energy Technology Data Exchange (ETDEWEB)

    Trivelpiece, Cory L., E-mail: cory@psu.ed [Department of Mechanical and Nuclear Engineering, The Pennsylvania, State University, University Park, PA 16802 (United States); Brenizer, J.S. [Department of Mechanical and Nuclear Engineering, The Pennsylvania, State University, University Park, PA 16802 (United States)

    2011-01-01

    A diameter of uncertainty (D{sub u}) was derived from a geometric uncertainty model describing the error that would be introduced into position-sensitive, coincidence neutron detection measurements by charged-particle transport phenomena and experimental setup. The transport of {alpha} and Li ions, produced by the {sup 10}B(n,{alpha}) {sup 7}Li reaction, through free-standing boro-phosphosilicate glass (BPSG) films was modeled using the Monte Carlo code SRIM, and the results of these simulations were used as input to determine D{sub u} for position-sensitive, coincidence techniques. The results of these calculations showed that D{sub u} is dependent on encoder separation, the angle of charged particle emission, and film thickness. For certain emission scenarios, the magnitude of D{sub u} is larger than the physical size of the neutron converting media that were being modeled. Spheres of uncertainty were developed that describe the difference in flight path times among the bounding-case emission scenarios that were considered in this work. It was shown the overlapping spheres represent emission angles and particle flight path lengths that would be difficult to resolve in terms of particle time-of-flight measurements. However, based on the timing resolution of current nuclear instrumentation, emission events that yield large D{sub u} can be discriminated by logical arguments during spectral deconvolution.

  5. Development of the model describing highly excited states of odd deformed nuclei

    International Nuclear Information System (INIS)

    Malov, L.A.; Solov'ev, V.G.

    1975-01-01

    An approximate method is given for solving the system of equations obtained earlier for describing the structure of states with intermediate and high energies in the framework of the model taking into account the interaction of quasiparticles with phonons. The new method possesses a number of advantages over the approximate methods of solving the system of equations mentioned. The study is performed for the example of an odd deformed nucleus when several one-quasiparticle components are taken into account at the same time

  6. Critical properties of a ferroelectric superlattice described by a transverse spin-1/2 Ising model

    International Nuclear Information System (INIS)

    Tabyaoui, A; Saber, M; Baerner, K; Ainane, A

    2007-01-01

    The phase transition properties of a ferroelectric superlattice with two alternating layers A and B described by a transverse spin-1/2 Ising model have been investigated using the effective field theory within a probability distribution technique that accounts for the self spin correlation functions. The Curie temperature T c , polarization and susceptibility have been obtained. The effects of the transverse field and the ferroelectric and antiferroelectric interfacial coupling strength between two ferroelectric materials are discussed. They relate to the physical properties of antiferroelectric/ferroelectric superlattices

  7. Model describing the effect of employment of the United States military in a complex emergency.

    Science.gov (United States)

    MacMillan, Donald S

    2005-01-01

    The end of the Cold War vastly altered the worldwide political landscape. With the loss of a main competitor, the United States (US) military has had to adapt its strategic, operational, and tactical doctrines to an ever-increasing variety of non-traditional missions, including humanitarian operations. Complex emergencies (CEs) are defined in this paper from a political and military perspective, various factors that contribute to their development are described, and issues resulting from the employment of US military forces are discussed. A model was developed to illustrate the course of a humanitarian emergency and the potential impact of a military response. The US intervention in Haiti, Northern Iraq, Kosovo, Somalia, Bosnia, and Rwanda serve as examples. A CE develops when there is civil conflict, loss of national governmental authority, a mass population movement, and massive economic failure, each leading to a general decline in food security. The military can alleviate a CE in four ways: (1) provide security for relief efforts; (2) enforce negotiated settlements; (3) provide security for non-combatants; and/or (4) employ logistical capabilities. The model incorporates Norton and Miskel's taxonomy of identifying failing states and helps illustrate the factors that lead to a CE. The model can be used to determine if and when military intervention will have the greatest impact. The model demonstrates that early military intervention and mission assignment within the core competencies of the forces can reverse the course of a CE. Further study will be needed to verify the model.

  8. Cosmological models described by a mixture of van der Waals fluid and dark energy

    International Nuclear Information System (INIS)

    Kremer, G.M.

    2003-01-01

    The Universe is modeled as a binary mixture whose constituents are described by a van der Waals fluid and by a dark energy density. The dark energy density is considered either as quintessence or as the Chaplygin gas. The irreversible processes concerning the energy transfer between the van der Waals fluid and the gravitational field are taken into account. This model can simulate (a) an inflationary period where the acceleration grows exponentially and the van der Waals fluid behaves like an inflaton, (b) an accelerated period where the acceleration is positive but it decreases and tends to zero whereas the energy density of the van der Waals fluid decays, (c) a decelerated period which corresponds to a matter dominated period with a non-negative pressure, and (d) a present accelerated period where the dark energy density outweighs the energy density of the van der Waals fluid

  9. The solar modulation of galactic comic rays as described by a time-dependent drift model

    International Nuclear Information System (INIS)

    Le Roux, J.A.

    1990-09-01

    The modulation process is understood to be an interaction between cosmic rays and the solar wind. The heliosphere and the observed modulation of cosmic rays in the heliosphere was reviewed and the time-dependence nature of the long-term modulation of cosmic rays highligted. A two-dimensional time-dependent drift model that describes the long-term modulation of cosmic-rays is presented. Application of the time-dependent drift model during times of increased solar activity showed that drift should be reduced during such periods. Isolated Forbush decreases were also studied in an effort to explain some observed trends in the properties of the Forbush decrease as a function of radial distance. The magnitude of the Forbush decrease and its recovery time were therefore studied as a function of radial distance in the equatorial plane. 154 refs., 95 figs., 1 tab

  10. Modeling arson - An exercise in qualitative model building

    Science.gov (United States)

    Heineke, J. M.

    1975-01-01

    A detailed example is given of the role of von Neumann and Morgenstern's 1944 'expected utility theorem' (in the theory of games and economic behavior) in qualitative model building. Specifically, an arsonist's decision as to the amount of time to allocate to arson and related activities is modeled, and the responsiveness of this time allocation to changes in various policy parameters is examined. Both the activity modeled and the method of presentation are intended to provide an introduction to the scope and power of the expected utility theorem in modeling situations of 'choice under uncertainty'. The robustness of such a model is shown to vary inversely with the number of preference restrictions used in the analysis. The fewer the restrictions, the wider is the class of agents to which the model is applicable, and accordingly more confidence is put in the derived results. A methodological discussion on modeling human behavior is included.

  11. Double porosity model to describe both permeability change and dissolution processes

    International Nuclear Information System (INIS)

    Niibori, Yuichi; Usui, Hideo; Chida, Taiji

    2015-01-01

    Cement is a practical material for constructing the geological disposal system of radioactive wastes. The dynamic behavior of both permeability change and dissolution process caused by a high pH groundwater was explained using a double porosity model assuming that each packed particle consists of the sphere-shaped aggregation of smaller particles. This model assumes two kinds of porosities between the particle clusters and between the particles, where the former porosity change mainly controls the permeability change of the bed, and the latter porosity change controls the diffusion of OH"- ions inducing the dissolution of silica. The fundamental equations consist of a diffusion equation of spherical coordinates of OH"- ions including the first-order reaction term and some equations describing the size changes of both the particles and the particle clusters with time. The change of over-all permeability of the packed bed is evaluated by Kozeny-Carman equation and the calculated radii of particle clusters. The calculated result well describes the experimental result of both permeability change and dissolution processes. (author)

  12. A mathematical model for describing the mechanical behaviour of root canal instruments.

    Science.gov (United States)

    Zhang, E W; Cheung, G S P; Zheng, Y F

    2011-01-01

    The purpose of this study was to establish a general mathematical model for describing the mechanical behaviour of root canal instruments by combining a theoretical analytical approach with a numerical finite-element method. Mathematical formulas representing the longitudinal (taper, helical angle and pitch) and cross-sectional configurations and area, the bending and torsional inertia, the curvature of the boundary point and the (geometry of) loading condition were derived. Torsional and bending stresses and the resultant deformation were expressed mathematically as a function of these geometric parameters, modulus of elasticity of the material and the applied load. As illustrations, three brands of NiTi endodontic files of different cross-sectional configurations (ProTaper, Hero 642, and Mani NRT) were analysed under pure torsion and pure bending situation by entering the model into a finite-element analysis package (ANSYS). Numerical results confirmed that mathematical models were a feasible method to analyse the mechanical properties and predict the stress and deformation for root canal instruments during root canal preparation. Mathematical and numerical model can be a suitable way to examine mechanical behaviours as a criterion of the instrument design and to predict the stress and strain experienced by the endodontic instruments during root canal preparation. © 2010 International Endodontic Journal.

  13. Cosmological model with viscosity media (dark fluid) described by an effective equation of state

    International Nuclear Information System (INIS)

    Ren Jie; Meng Xinhe

    2006-01-01

    A generally parameterized equation of state (EOS) is investigated in the cosmological evolution with bulk viscosity media modelled as dark fluid, which can be regarded as a unification of dark energy and dark matter. Compared with the case of the perfect fluid, this EOS has possessed four additional parameters, which can be interpreted as the case of the non-perfect fluid with time-dependent viscosity or the model with variable cosmological constant. From this general EOS, a completely integrable dynamical equation to the scale factor is obtained with its solution explicitly given out. (i) In this parameterized model of cosmology, for a special choice of the parameters we can explain the late-time accelerating expansion universe in a new view. The early inflation, the median (relatively late time) deceleration, and the recently cosmic acceleration may be unified in a single equation. (ii) A generalized relation of the Hubble parameter scaling with the redshift is obtained for some cosmology interests. (iii) By using the SNe Ia data to fit the effective viscosity model we show that the case of matter described by p=0 plus with effective viscosity contributions can fit the observational gold data in an acceptable level

  14. Describing the Process of Adopting Nutrition and Fitness Apps: Behavior Stage Model Approach.

    Science.gov (United States)

    König, Laura M; Sproesser, Gudrun; Schupp, Harald T; Renner, Britta

    2018-03-13

    Although mobile technologies such as smartphone apps are promising means for motivating people to adopt a healthier lifestyle (mHealth apps), previous studies have shown low adoption and continued use rates. Developing the means to address this issue requires further understanding of mHealth app nonusers and adoption processes. This study utilized a stage model approach based on the Precaution Adoption Process Model (PAPM), which proposes that people pass through qualitatively different motivational stages when adopting a behavior. To establish a better understanding of between-stage transitions during app adoption, this study aimed to investigate the adoption process of nutrition and fitness app usage, and the sociodemographic and behavioral characteristics and decision-making style preferences of people at different adoption stages. Participants (N=1236) were recruited onsite within the cohort study Konstanz Life Study. Use of mobile devices and nutrition and fitness apps, 5 behavior adoption stages of using nutrition and fitness apps, preference for intuition and deliberation in eating decision-making (E-PID), healthy eating style, sociodemographic variables, and body mass index (BMI) were assessed. Analysis of the 5 behavior adoption stages showed that stage 1 ("unengaged") was the most prevalent motivational stage for both nutrition and fitness app use, with half of the participants stating that they had never thought about using a nutrition app (52.41%, 533/1017), whereas less than one-third stated they had never thought about using a fitness app (29.25%, 301/1029). "Unengaged" nonusers (stage 1) showed a higher preference for an intuitive decision-making style when making eating decisions, whereas those who were already "acting" (stage 4) showed a greater preference for a deliberative decision-making style (F 4,1012 =21.83, Pdigital interventions. This study highlights that new user groups might be better reached by apps designed to address a more intuitive

  15. Species-free species distribution models describe macroecological properties of protected area networks.

    Science.gov (United States)

    Robinson, Jason L; Fordyce, James A

    2017-01-01

    Among the greatest challenges facing the conservation of plants and animal species in protected areas are threats from a rapidly changing climate. An altered climate creates both challenges and opportunities for improving the management of protected areas in networks. Increasingly, quantitative tools like species distribution modeling are used to assess the performance of protected areas and predict potential responses to changing climates for groups of species, within a predictive framework. At larger geographic domains and scales, protected area network units have spatial geoclimatic properties that can be described in the gap analysis typically used to measure or aggregate the geographic distributions of species (stacked species distribution models, or S-SDM). We extend the use of species distribution modeling techniques in order to model the climate envelope (or "footprint") of individual protected areas within a network of protected areas distributed across the 48 conterminous United States and managed by the US National Park System. In our approach we treat each protected area as the geographic range of a hypothetical endemic species, then use MaxEnt and 5 uncorrelated BioClim variables to model the geographic distribution of the climatic envelope associated with each protected area unit (modeling the geographic area of park units as the range of a species). We describe the individual and aggregated climate envelopes predicted by a large network of 163 protected areas and briefly illustrate how macroecological measures of geodiversity can be derived from our analysis of the landscape ecological context of protected areas. To estimate trajectories of change in the temporal distribution of climatic features within a protected area network, we projected the climate envelopes of protected areas in current conditions onto a dataset of predicted future climatic conditions. Our results suggest that the climate envelopes of some parks may be locally unique or have

  16. Methodological Bases for Describing Risks of the Enterprise Business Model in Integrated Reporting

    Directory of Open Access Journals (Sweden)

    Nesterenko Oksana O.

    2017-12-01

    Full Text Available The aim of the article is to substantiate the methodological bases for describing the business and accounting risks of an enterprise business model in integrated reporting for their timely detection and assessment, and develop methods for their leveling or minimizing and possible prevention. It is proposed to consider risks in the process of forming integrated reporting from two sides: first, risks that arise in the business model of an organization and should be disclosed in its integrated report; second, accounting risks of integrated reporting, which should be taken into account by members of the cross-sectoral working group and management personnel in the process of forming and promulgating integrated reporting. To develop an adequate accounting and analytical tool for disclosure of information about the risks of the business model and integrated reporting, their leveling or minimization, in the article a terminological analysis of the essence of entrepreneurial and accounting risks is carried out. The entrepreneurial risk is defined as an objective-subjective economic category that characterizes the probability of negative or positive consequences of economic-social-ecological activity within the framework of the business model of an enterprise under uncertainty. The accounting risk is suggested to be understood as the probability of unfavorable consequences as a result of organizational, methodological errors in the integrated accounting system, which present threat to the quality, accuracy and reliability of the reporting information on economic, social and environmental activities in integrated reporting as well as threat of inappropriate decision-making by stakeholders based on the integrated report. For the timely identification of business risks and maximum leveling of the influence of accounting risks on the process of formation and publication of integrated reporting, in the study the place of entrepreneurial and accounting risks in

  17. Model tool to describe chemical structures in XML format utilizing structural fragments and chemical ontology.

    Science.gov (United States)

    Sankar, Punnaivanam; Alain, Krief; Aghila, Gnanasekaran

    2010-05-24

    We have developed a model structure-editing tool, ChemEd, programmed in JAVA, which allows drawing chemical structures on a graphical user interface (GUI) by selecting appropriate structural fragments defined in a fragment library. The terms representing the structural fragments are organized in fragment ontology to provide a conceptual support. ChemEd describes the chemical structure in an XML document (ChemFul) with rich semantics explicitly encoding the details of the chemical bonding, the hybridization status, and the electron environment around each atom. The document can be further processed through suitable algorithms and with the support of external chemical ontologies to generate understandable reports about the functional groups present in the structure and their specific environment.

  18. Computer-aided Nonlinear Control System Design Using Describing Function Models

    CERN Document Server

    Nassirharand, Amir

    2012-01-01

    A systematic computer-aided approach provides a versatile setting for the control engineer to overcome the complications of controller design for highly nonlinear systems. Computer-aided Nonlinear Control System Design provides such an approach based on the use of describing functions. The text deals with a large class of nonlinear systems without restrictions on the system order, the number of inputs and/or outputs or the number, type or arrangement of nonlinear terms. The strongly software-oriented methods detailed facilitate fulfillment of tight performance requirements and help the designer to think in purely nonlinear terms, avoiding the expedient of linearization which can impose substantial and unrealistic model limitations and drive up the cost of the final product. Design procedures are presented in a step-by-step algorithmic format each step being a functional unit with outputs that drive the other steps. This procedure may be easily implemented on a digital computer with example problems from mecha...

  19. Regression models describing Rosa hybrida response to day/night temperature and photosynthetic photon flux

    International Nuclear Information System (INIS)

    Hopper, D.A.; Hammer, P.A.

    1991-01-01

    A central composite rotatable design was used to estimate quadratic equations describing the relationship of irradiance, as measured by photosynthetic photon flux (PPF), and day (DT) and night (NT) temperatures to the growth and development of Rosa hybrida L. in controlled environments. Plants were subjected to 15 treatment combinations of the PPF, DT, and NT according to the coding of the design matrix. Day and night length were each 12 hours. Environmental factor ranges were chosen to include conditions representative of winter and spring commercial greenhouse production environments in the midwestern United States. After an initial hard pinch, 11 plant growth characteristics were measured every 10 days and at flowering. Four plant characteristics were recorded to describe flower bud development. Response surface equations were displayed as three-dimensional plots, with DT and NT as the base axes and the plant character on the z-axis while PPF was held constant. Response surfaces illustrated the plant response to interactions of DT and NT, while comparisons between plots at different PPF showed the overall effect of PPF. Canonical analysis of all regression models revealed the stationary point and general shape of the response surface. All stationary points of the significant models were located outside the original design space, and all but one surface was a saddle shape. Both the plots and analysis showed greater stem diameter, as well as higher fresh and dry weights of stems, leaves, and flower buds to occur at flowering under combinations of low DT (less than or equal to 17C) and low NT (less than or equal to 14C). However, low DT and NT delayed both visible bud formation and development to flowering. Increased PPF increased overall flower stem quality by increasing stem diameter and the fresh and dry weights of all plant parts at flowering, as well as decreased time until visible bud formation and flowering. These results summarize measured development at

  20. Inclusion of models to describe severe accident conditions in the fuel simulation code DIONISIO

    Energy Technology Data Exchange (ETDEWEB)

    Lemes, Martín; Soba, Alejandro [Sección Códigos y Modelos, Gerencia Ciclo del Combustible Nuclear, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires (Argentina); Daverio, Hernando [Gerencia Reactores y Centrales Nucleares, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires (Argentina); Denis, Alicia [Sección Códigos y Modelos, Gerencia Ciclo del Combustible Nuclear, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires (Argentina)

    2017-04-15

    The simulation of fuel rod behavior is a complex task that demands not only accurate models to describe the numerous phenomena occurring in the pellet, cladding and internal rod atmosphere but also an adequate interconnection between them. In the last years several models have been incorporated to the DIONISIO code with the purpose of increasing its precision and reliability. After the regrettable events at Fukushima, the need for codes capable of simulating nuclear fuels under accident conditions has come forth. Heat removal occurs in a quite different way than during normal operation and this fact determines a completely new set of conditions for the fuel materials. A detailed description of the different regimes the coolant may exhibit in such a wide variety of scenarios requires a thermal-hydraulic formulation not suitable to be included in a fuel performance code. Moreover, there exist a number of reliable and famous codes that perform this task. Nevertheless, and keeping in mind the purpose of building a code focused on the fuel behavior, a subroutine was developed for the DIONISIO code that performs a simplified analysis of the coolant in a PWR, restricted to the more representative situations and provides to the fuel simulation the boundary conditions necessary to reproduce accidental situations. In the present work this subroutine is described and the results of different comparisons with experimental data and with thermal-hydraulic codes are offered. It is verified that, in spite of its comparative simplicity, the predictions of this module of DIONISIO do not differ significantly from those of the specific, complex codes.

  1. Theoretical models for describing longitudinal bunch compression in the neutralized drift compression experiment

    Directory of Open Access Journals (Sweden)

    Adam B. Sefkow

    2006-09-01

    Full Text Available Heavy ion drivers for warm dense matter and heavy ion fusion applications use intense charge bunches which must undergo transverse and longitudinal compression in order to meet the requisite high current densities and short pulse durations desired at the target. The neutralized drift compression experiment (NDCX at the Lawrence Berkeley National Laboratory is used to study the longitudinal neutralized drift compression of a space-charge-dominated ion beam, which occurs due to an imposed longitudinal velocity tilt and subsequent neutralization of the beam’s space charge by background plasma. Reduced theoretical models have been used in order to describe the realistic propagation of an intense charge bunch through the NDCX device. A warm-fluid model is presented as a tractable computational tool for investigating the nonideal effects associated with the experimental acceleration gap geometry and voltage waveform of the induction module, which acts as a means to pulse shape both the velocity and line density profiles. Self-similar drift compression solutions can be realized in order to transversely focus the entire charge bunch to the same focal plane in upcoming simultaneous transverse and longitudinal focusing experiments. A kinetic formalism based on the Vlasov equation has been employed in order to show that the peaks in the experimental current profiles are a result of the fact that only the central portion of the beam contributes effectively to the main compressed pulse. Significant portions of the charge bunch reside in the nonlinearly compressing part of the ion beam because of deviations between the experimental and ideal velocity tilts. Those regions form a pedestal of current around the central peak, thereby decreasing the amount of achievable longitudinal compression and increasing the pulse durations achieved at the focal plane. A hybrid fluid-Vlasov model which retains the advantages of both the fluid and kinetic approaches has been

  2. Introducing mixotrophy into a biogeochemical model describing an eutrophied coastal ecosystem: The Southern North Sea

    Science.gov (United States)

    Ghyoot, Caroline; Lancelot, Christiane; Flynn, Kevin J.; Mitra, Aditee; Gypens, Nathalie

    2017-09-01

    Most biogeochemical/ecological models divide planktonic protists between phototrophs (phytoplankton) and heterotrophs (zooplankton). However, a large number of planktonic protists are able to combine several mechanisms of carbon and nutrient acquisition. Not representing these multiple mechanisms in biogeochemical/ecological models describing eutrophied coastal ecosystems can potentially lead to different conclusions regarding ecosystem functioning, especially regarding the success of harmful algae, which are often reported as mixotrophic. This modelling study investigates the implications for trophic dynamics of including 3 contrasting forms of mixotrophy, namely osmotrophy (using alkaline phosphatase activity, APA), non-constitutive mixotrophy (acquired phototrophy by microzooplankton) and also constitutive mixotrophy. The application is in the Southern North Sea, an ecosystem that faced, between 1985 and 2005, a significant increase in the nutrient supply N:P ratio (from 31 to 81 mol N:P). The comparison with a traditional model shows that, when the winter N:P ratio in the Southern North Sea is above 22 molN molP-1 (as occurred from mid-1990s), APA allows a 3-32% increase of annual gross primary production (GPP). In result of the higher GPP, the annual sedimentation increases as well as the bacterial production. By contrast, APA does not affect the export of matter to higher trophic levels because the increased GPP is mainly due to Phaeocystis colonies, which are not grazed by copepods. Under high irradiance, non-constitutive mixotrophy appreciably increases annual GPP, transfer to higher trophic levels, sedimentation, and nutrient remineralisation. In this ecosystem, non-constitutive mixotrophy is also observed to have an indirect stimulating effect on diatoms. Constitutive mixotrophy in nanoflagellates appears to have little influence on this ecosystem functioning. An important conclusion from this work is that contrasting forms of mixotrophy have different

  3. Longitudinal qualitative study describing family physicians' experiences with attempting to integrate physical activity prescriptions in their practice: 'It's not easy to change habits'.

    Science.gov (United States)

    Bélanger, Mathieu; Phillips, Emily Wolfe; O'Rielly, Connor; Mallet, Bertin; Aubé, Shane; Doucet, Marylène; Couturier, Jonathan; Mallet, Maxime; Martin, Jessica; Gaudet, Christine; Murphy, Nathalie; Brunet, Jennifer

    2017-07-13

    Physical activity (PA) prescriptions provided by family physicians can promote PA participation among patients, but few physicians regularly write PA prescriptions. The objective of this study was to describe family physicians' experiences of trying to implement written PA prescriptions into their practice. Longitudinal qualitative study where participants were interviewed four times during a 12-month period. After the first interview, they were provided with PA prescription pads. Data were analysed using thematic analysis. Family medicine clinics in New Brunswick, Canada. Family physicians (n=11) with no prior experience writing PA prescriptions, but who expressed interest in changing their practice to implement written PA prescriptions. Initially, participants exhibited confidence in their ability to write PA prescriptions in the future and intended to write prescriptions. However, data from the follow-up interviews indicated that the rate of implementation was lower than anticipated by participants and prescriptions were not part of their regular practice. Two themes emerged as factors explaining the gap between their intentions and behaviours: (1) uncertainty about the effectiveness of written PA prescription, and (2) practical concerns (eg, changing well-established habits, time constraints, systemic institutional barriers). It may be effective to increase awareness among family physicians about the effectiveness of writing PA prescriptions and address barriers related to how their practice is organised in order to promote written PA prescription rates. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  4. A methodology for acquiring qualitative knowledge for probabilistic graphical models

    DEFF Research Database (Denmark)

    Kjærulff, Uffe Bro; Madsen, Anders L.

    2004-01-01

    We present a practical and general methodology that simplifies the task of acquiring and formulating qualitative knowledge for constructing probabilistic graphical models (PGMs). The methodology efficiently captures and communicates expert knowledge, and has significantly eased the model...

  5. A unified model to describe the anisotropic viscoplastic behavior of Zircaloy-4 cladding tubes

    International Nuclear Information System (INIS)

    Delobelle, P.; Robinet, P.; Bouffioux, P.; Geyer, P.; Pichon, I. Le

    1996-01-01

    This paper presents the constitutive equations of a unified viscoplastic model and its validation with experimental data. The mechanical tests were carried out in a temperature range of 20 to 400 C on both cold-worked stress-relieved and fully annealed Zircaloy-4 tubes. Although their geometry (14.3 by 1.2 mm) is different, the crystallographic texture was close to that expected in the cladding tubes. To characterize the anisotropy, mechanical tests were performed under both monotonic and cyclic uni- and bi-directional loadings, i.e., tension-compression, tension-torsion, and tension-internal pressure tests. The results obtained at ambient temperatures and the independence of the ratio R p = var-epsilon θθ p /var-epsilon zz p , with respect to temperature would seem to indicate that the set of anisotropy coefficients does not depend on temperature. Zircaloy-4 material also has a slight supplementary hardening during out-of-phase cyclic loading. The authors propose to extend the formulation of a unified viscoplastic model, developed and identified elsewhere for other initially isotropic materials, to the case of Zircaloy-4. Generally speaking, anisotropy is introduced through fourth order tensors affecting the flow directions, the linear kinematical hardening components, as well as the dynamic and static recoveries of the forementioned hardening variables. The ability of the model to describe all the mechanical properties of the material is shown. The application of the model to simulate mechanical tests (tension, creep, and relaxation) performed on true CWSR Zircaloy-4 cladding tubes with low tin content is also presented

  6. Comparison of three nonlinear models to describe long-term tag shedding by lake trout

    Science.gov (United States)

    Fabrizio, Mary C.; Swanson, Bruce L.; Schram, Stephen T.; Hoff, Michael H.

    1996-01-01

    We estimated long-term tag-shedding rates for lake trout Salvelinus namaycush using two existing models and a model we developed to account for the observed permanence of some tags. Because tag design changed over the course of the study, we examined tag-shedding rates for three types of numbered anchor tags (Floy tags FD-67, FD-67C, and FD-68BC) and an unprinted anchor tag (FD-67F). Lake trout from the Gull Island Shoal region, Lake Superior, were double-tagged, and subsequent recaptures were monitored in annual surveys conducted from 1974 to 1992. We modeled tag-shedding rates, using time at liberty and probabilities of tag shedding estimated from fish released in 1974 and 1978–1983 and later recaptured. Long-term shedding of numbered anchor tags in lake trout was best described by a nonlinear model with two parameters: an instantaneous tag-shedding rate and a constant representing the proportion of tags that were never shed. Although our estimates of annual shedding rates varied with tag type (0.300 for FD-67, 0.441 for FD-67C, and 0.656 for FD-68BC), differences were not significant. About 36% of tags remained permanently affixed to the fish. Of the numbered tags that were shed (about 64%), two mechanisms contributed to tag loss: disintegration and dislodgment. Tags from about 11% of recaptured fish had disintegrated, but most tags were dislodged. Unprinted tags were shed at a significant but low rate immediately after release, but the long-term, annual shedding rate of these tags was only 0.013. Compared with unprinted tags, numbered tags dislodged at higher annual rates; we hypothesized that this was due to the greater frictional drag associated with the larger cross-sectional area of numbered tags.

  7. Yeast for Mathematicians: A Ferment of Discovery and Model Competition to Describe Data.

    Science.gov (United States)

    Lewis, Matthew; Powell, James

    2017-02-01

    In addition to the memorization, algorithmic skills and vocabulary which are the default focus in many mathematics classrooms, professional mathematicians are expected to creatively apply known techniques, construct new mathematical approaches and communicate with and about mathematics. We propose that students can learn these professional, higher-level skills through Laboratory Experiences in Mathematical Biology which put students in the role of mathematics researcher creating mathematics to describe and understand biological data. Here we introduce a laboratory experience centered on yeast (Saccharomyces cerevisiae) growing in a small capped flask with a jar to collect carbon dioxide created during yeast growth and respiration. The lab requires no specialized equipment and can easily be run in the context of a college math class. Students collect data and develop mathematical models to explain the data. To help place instructors in the role of mentor/collaborator (as opposed to jury/judge), we facilitate the lab using model competition judged via Bayesian Information Criterion. This article includes details about the class activity conducted, student examples and pedagogical strategies for success.

  8. Can a Linear Sigma Model Describe Walking Gauge Theories at Low Energies?

    Science.gov (United States)

    Gasbarro, Andrew

    2018-03-01

    In recent years, many investigations of confining Yang Mills gauge theories near the edge of the conformal window have been carried out using lattice techniques. These studies have revealed that the spectrum of hadrons in nearly conformal ("walking") gauge theories differs significantly from the QCD spectrum. In particular, a light singlet scalar appears in the spectrum which is nearly degenerate with the PNGBs at the lightest currently accessible quark masses. This state is a viable candidate for a composite Higgs boson. Presently, an acceptable effective field theory (EFT) description of the light states in walking theories has not been established. Such an EFT would be useful for performing chiral extrapolations of lattice data and for serving as a bridge between lattice calculations and phenomenology. It has been shown that the chiral Lagrangian fails to describe the IR dynamics of a theory near the edge of the conformal window. Here we assess a linear sigma model as an alternate EFT description by performing explicit chiral fits to lattice data. In a combined fit to the Goldstone (pion) mass and decay constant, a tree level linear sigma model has a Χ2/d.o.f. = 0.5 compared to Χ2/d.o.f. = 29.6 from fitting nextto-leading order chiral perturbation theory. When the 0++ (σ) mass is included in the fit, Χ2/d.o.f. = 4.9. We remark on future directions for providing better fits to the σ mass.

  9. A Minimal Model Describing Hexapedal Interlimb Coordination: The Tegotae-Based Approach

    Directory of Open Access Journals (Sweden)

    Dai Owaki

    2017-06-01

    Full Text Available Insects exhibit adaptive and versatile locomotion despite their minimal neural computing. Such locomotor patterns are generated via coordination between leg movements, i.e., an interlimb coordination, which is largely controlled in a distributed manner by neural circuits located in thoracic ganglia. However, the mechanism responsible for the interlimb coordination still remains elusive. Understanding this mechanism will help us to elucidate the fundamental control principle of animals' agile locomotion and to realize robots with legs that are truly adaptive and could not be developed solely by conventional control theories. This study aims at providing a “minimal" model of the interlimb coordination mechanism underlying hexapedal locomotion, in the hope that a single control principle could satisfactorily reproduce various aspects of insect locomotion. To this end, we introduce a novel concept we named “Tegotae,” a Japanese concept describing the extent to which a perceived reaction matches an expectation. By using the Tegotae-based approach, we show that a surprisingly systematic design of local sensory feedback mechanisms essential for the interlimb coordination can be realized. We also use a hexapod robot we developed to show that our mathematical model of the interlimb coordination mechanism satisfactorily reproduces various insects' gait patterns.

  10. Fast fission phenomenon, deep inelastic reactions and compound nucleus formation described within a dynamical macroscopic model

    International Nuclear Information System (INIS)

    Gregoire, C.; Ngo, C.; Remaud, B.

    1982-01-01

    We present a dynamical model to describe dissipative heavy ion reactions. It treats explicitly the relative motion of the two ions, the mass asymmetry of the system and the projection of the isospin of each ion. The deformations, which are induced during the collision, are simulated with a time-dependent interaction potential. This is done by a time-dependent transition between a sudden interaction potential in the entrance channel and an adiabatic potential in the exit channel. The model allows us to compute the compound-nucleus cross section and multidifferential cross-sections for deep inelastic reactions. In addition, for some systems, and under certain conditions which are discussed in detail, a new dissipative heavy ion collision appears: fast-fission phenomenon which has intermediate properties between deep inelastic and compound nucleus reactions. The calculated properties concerning fast fission are compared with experimental results and reproduce some of those which could not be understood as belonging to deep inelastic or compound-nucleus reactions. (orig.)

  11. The Systems Biology Markup Language (SBML) Level 3 Package: Qualitative Models, Version 1, Release 1.

    Science.gov (United States)

    Chaouiya, Claudine; Keating, Sarah M; Berenguier, Duncan; Naldi, Aurélien; Thieffry, Denis; van Iersel, Martijn P; Le Novère, Nicolas; Helikar, Tomáš

    2015-09-04

    Quantitative methods for modelling biological networks require an in-depth knowledge of the biochemical reactions and their stoichiometric and kinetic parameters. In many practical cases, this knowledge is missing. This has led to the development of several qualitative modelling methods using information such as, for example, gene expression data coming from functional genomic experiments. The SBML Level 3 Version 1 Core specification does not provide a mechanism for explicitly encoding qualitative models, but it does provide a mechanism for SBML packages to extend the Core specification and add additional syntactical constructs. The SBML Qualitative Models package for SBML Level 3 adds features so that qualitative models can be directly and explicitly encoded. The approach taken in this package is essentially based on the definition of regulatory or influence graphs. The SBML Qualitative Models package defines the structure and syntax necessary to describe qualitative models that associate discrete levels of activities with entity pools and the transitions between states that describe the processes involved. This is particularly suited to logical models (Boolean or multi-valued) and some classes of Petri net models can be encoded with the approach.

  12. Pharmacodynamic Model To Describe the Concentration-Dependent Selection of Cefotaxime-Resistant Escherichia coli

    Science.gov (United States)

    Olofsson, Sara K.; Geli, Patricia; Andersson, Dan I.; Cars, Otto

    2005-01-01

    Antibiotic dosing regimens may vary in their capacity to select mutants. Our hypothesis was that selection of a more resistant bacterial subpopulation would increase with the time within a selective window (SW), i.e., when drug concentrations fall between the MICs of two strains. An in vitro kinetic model was used to study the selection of two Escherichia coli strains with different susceptibilities to cefotaxime. The bacterial mixtures were exposed to cefotaxime for 24 h and SWs of 1, 2, 4, 8, and 12 h. A mathematical model was developed that described the selection of preexisting and newborn mutants and the post-MIC effect (PME) as functions of pharmacokinetic parameters. Our main conclusions were as follows: (i) the selection between preexisting mutants increased with the time within the SW; (ii) the emergence and selection of newborn mutants increased with the time within the SW (with a short time, only 4% of the preexisting mutants were replaced by newborn mutants, compared to the longest times, where 100% were replaced); and (iii) PME increased with the area under the concentration-time curve (AUC) and was slightly more pronounced with a long elimination half-life (T1/2) than with a short T1/2 situation, when AUC is fixed. We showed that, in a dynamic competition between strains with different levels of resistance, the appearance of newborn high-level resistant mutants from the parental strains and the PME can strongly affect the outcome of the selection and that pharmacodynamic models can be used to predict the outcome of resistance development. PMID:16304176

  13. Ecohydrology in Mediterranean areas: a numerical model to describe growing seasons out of phase with precipitations

    Directory of Open Access Journals (Sweden)

    D. Pumo

    2008-02-01

    Full Text Available The probabilistic description of soil moisture dynamics is a relatively new topic in hydrology. The most common ecohydrological models start from a stochastic differential equation describing the soil water balance, where the unknown quantity, the soil moisture, depends both on spaces and time. Most of the solutions existing in literature are obtained in a probabilistic framework and under steady-state condition; even if this last condition allows the analytical handling of the problem, it has considerably simplified the same problem by subtracting generalities from it.

    The steady-state hypothesis, appears perfectly applicable in arid and semiarid climatic areas like those of African's or middle American's savannas, but it seems to be no more valid in areas with Mediterranean climate, where, notoriously, the wet season foregoes the growing season, recharging water into the soil. This moisture stored at the beginning of the growing season (known as soil moisture initial condition has a great importance, especially for deep-rooted vegetation, by enabling survival in absence of rainfalls during the growing season and, however, keeping the water stress low during the first period of the same season.

    The aim of this paper is to analyze the soil moisture dynamics using a simple non-steady numerical ecohydrological model. The numerical model here proposed is able to reproduce soil moisture probability density function, obtained analytically in previous studies for different climates and soils in steady-state conditions; consequently it can be used to compute both the soil moisture time-profile and the vegetation static water stress time-profile in non-steady conditions.

    Here the differences between the steady-analytical and the non-steady numerical probability density functions are analyzed, showing how the proposed numerical model is able to capture the effects of winter recharge on the soil moisture. The dynamic

  14. The generalized model of polypeptide chain describing the helix-coil transition in biopolymers

    International Nuclear Information System (INIS)

    Mamasakhlisov, E.S.; Badasyan, A.V.; Tsarukyan, A.V.; Grigoryan, A.V.; Morozov, V.F.

    2005-07-01

    In this paper we summarize some results of our theoretical investigations of helix-coil transition both in single-strand (polypeptides) and two-strand (polynucleotides) macromolecules. The Hamiltonian of the Generalized Model of Polypeptide Chain (GMPC) is introduced to describe the system in which the conformations are correlated over some dimensional range Δ (it equals 3 for polypeptide, because one H-bond fixes three pairs of rotation, for double strand DNA it equals to one chain rigidity because of impossibility of loop formation on the scale less than Δ). The Hamiltonian does not contain any parameter designed especially for helix-coil transition and uses pure molecular microscopic parameters (the energy of hydrogen bond formation, reduced partition function of repeated unit, the number of repeated units fixed by one hydrogen bond, the energies of interaction between the repeated units and the solvent molecules). To calculate averages we evaluate the partition function using the transfer-matrix approach. The GMPC allowed to describe the influence of a number of factors, affecting the transition, basing on a unified microscopic approach. Thus we obtained, that solvents change transition temperature and interval in different ways, depending on type of solvent and on energy of solvent- macromolecule interaction; stacking on the background of H-bonding increases stability and decreases cooperativity of melting. For heterogeneous DNA we could analytically derive well known formulae for transition temperature and interval. In the framework of GMPC we calculate and show the difference of two order parameters of helix-coil transition - the helicity degree, and the average fraction of repeated units in helical conformation. Given article has the aim to review the results obtained during twenty years in the context of GMPC. (author)

  15. Conceptual modeling of postmortem evaluation findings to describe dairy cow deaths.

    Science.gov (United States)

    McConnel, C S; Garry, F B; Hill, A E; Lombard, J E; Gould, D H

    2010-01-01

    Dairy cow mortality levels in the United States are excessive and increasing over time. To better define cause and effect and combat rising mortality, clearer definitions of the reasons that cows die need to be acquired through thorough necropsy-based postmortem evaluations. The current study focused on organizing information generated from postmortem evaluations into a monitoring system that is based on the fundamentals of conceptual modeling and that will potentially be translatable into on-farm relational databases. This observational study was conducted on 3 high-producing, commercial dairies in northern Colorado. Throughout the study period a thorough postmortem evaluation was performed by veterinarians on cows that died on each dairy. Postmortem data included necropsy findings, life-history features (e.g., birth date, lactation number, lactational and reproductive status), clinical history and treatments, and pertinent aspects of operational management that were subject to change and considered integral to the poor outcome. During this study, 174 postmortem evaluations were performed. Postmortem evaluation results were conceptually modeled to view each death within the context of the web of factors influencing the dairy and the cow. Categories were formulated describing mortality in terms of functional characteristics potentially amenable to easy performance evaluation, management oversight, and research. In total, 21 death categories with 7 category themes were created. Themes included specific disease processes with variable etiologies, failure of disease recognition or treatment, traumatic events, multifactorial failures linked to transition or negative energy balance issues, problems with feed management, miscellaneous events not amenable to prevention or treatment, and undetermined causes. Although postmortem evaluations provide the relevant information necessary for framing a cow's death, a restructuring of on-farm databases is needed to integrate this

  16. Rapid-relocation model for describing high-fluence retention of rare gases implanted in solids

    Science.gov (United States)

    Wittmaack, K.

    2009-09-01

    to be due to bombardment induced relocation and reemission, only the remaining 10% (or less) can be attributed to sputter erosion. The relocation efficiency is interpreted as the 'speed' of radiation enhanced diffusion towards the surface. The directionality of diffusion is attributed to the gradient of the defect density on the large-depth side of the damage distribution where most of the implanted rare gas atoms come to rest. Based on SRIM calculations, two representative parameters are defined, the peak number of lattice displacements, Nd,m, and the spacing, △ zr,d, between the peaks of the range and the damage distributions. Support in favour of rapid rare gas relocation by radiation enhanced diffusion is provided by the finding that the relocation efficiencies for Ar and Xe, which vary by up to one order of magnitude, scale as Ψ=kN/Δz, independent to the implantation energy (10-80 keV Ar, 10-500 keV Xe), within an error margin of only ± 15%. The parameter k contains the properties of the implanted rare gas atoms. A recently described computer simulation model, which assumed that the pressure established by the implanted gas drives reemission, is shown to reproduce measured Xe profiles quite well, but only at that energy at which the fitting parameter of the model was determined (140 keV). Using the same parameter at other energies, deviations by up to a factor of four are observed.

  17. SDG and qualitative trend based model multiple scale validation

    Science.gov (United States)

    Gao, Dong; Xu, Xin; Yin, Jianjin; Zhang, Hongyu; Zhang, Beike

    2017-09-01

    Verification, Validation and Accreditation (VV&A) is key technology of simulation and modelling. For the traditional model validation methods, the completeness is weak; it is carried out in one scale; it depends on human experience. The SDG (Signed Directed Graph) and qualitative trend based multiple scale validation is proposed. First the SDG model is built and qualitative trends are added to the model. And then complete testing scenarios are produced by positive inference. The multiple scale validation is carried out by comparing the testing scenarios with outputs of simulation model in different scales. Finally, the effectiveness is proved by carrying out validation for a reactor model.

  18. AI/OR computational model for integrating qualitative and quantitative design methods

    Science.gov (United States)

    Agogino, Alice M.; Bradley, Stephen R.; Cagan, Jonathan; Jain, Pramod; Michelena, Nestor

    1990-01-01

    A theoretical framework for integrating qualitative and numerical computational methods for optimally-directed design is described. The theory is presented as a computational model and features of implementations are summarized where appropriate. To demonstrate the versatility of the methodology we focus on four seemingly disparate aspects of the design process and their interaction: (1) conceptual design, (2) qualitative optimal design, (3) design innovation, and (4) numerical global optimization.

  19. Predictions and implications of a poisson process model to describe corrosion of transuranic waste drums

    International Nuclear Information System (INIS)

    Lyon, B.F.; Holmes, J.A.; Wilbert, K.A.

    1995-01-01

    A risk assessment methodology is described in this paper to compare risks associated with immediate or near-term retrieval of transuranic (TRU) waste drums from bermed storage versus delayed retrieval. Assuming a Poisson process adequately describes corrosion, significant breaching of drums is expected to begin at - 15 and 24 yr for pitting and general corrosion, respectively. Because of this breaching, more risk will be incurred by delayed than by immediate retrieval

  20. Development and application of an asymmetric deformation model to describe the fuel rod behaviour during LOCA

    International Nuclear Information System (INIS)

    Chakraborty, A.K.; Schubert, J.D.

    1983-01-01

    For calculation of clad ballooning from single rod and rod bundle experiments a model considering the influences of azimuthal temperature gradients due to the existing eccentricity of the pellets has been developed. This model is based on the secondary creep model of Norton and on the concentric deformation model ending in cladding burst as proposed by F. Erbacher. The new model considers the azimuthal temperature differences along the cladding and the resulting differences in deformations. With this model, calculations of cladding burst deformations from single rod and rod bundle experiments are performed with good agreement

  1. Review Of Applied Mathematical Models For Describing The Behaviour Of Aqueous Humor In Eye Structures

    Science.gov (United States)

    Dzierka, M.; Jurczak, P.

    2015-12-01

    In the paper, currently used methods for modeling the flow of the aqueous humor through eye structures are presented. Then a computational model based on rheological models of Newtonian and non-Newtonian fluids is proposed. The proposed model may be used for modeling the flow of the aqueous humor through the trabecular meshwork. The trabecular meshwork is modeled as an array of rectilinear parallel capillary tubes. The flow of Newtonian and non-Newtonian fluids is considered. As a results of discussion mathematical equations of permeability of porous media and velocity of fluid flow through porous media have been received.

  2. Disaster Reintegration Model: A Qualitative Analysis on Developing Korean Disaster Mental Health Support Model

    Directory of Open Access Journals (Sweden)

    Yun-Jung Choi

    2018-02-01

    Full Text Available This study sought to describe the mental health problems experienced by Korean disaster survivors, using a qualitative research method to provide empirical resources for effective disaster mental health support in Korea. Participants were 16 adults or elderly adults who experienced one or more disasters at least 12 months ago recruited via theoretical sampling. Participants underwent in-depth individual interviews on their disaster experiences, which were recorded and transcribed for qualitative analysis, which followed Strauss and Corbin’s (1998 Grounded theory. After open coding, participants’ experiences were categorized into 130 codes, 43 sub-categories and 17 categories. The categories were further analyzed in a paradigm model, conditional model and the Disaster Reintegration Model, which proposed potentially effective mental health recovery strategies for disaster survivors, health providers and administrators. To provide effective assistance for mental health recovery of disaster survivors, both personal and public resilience should be promoted while considering both cultural and spiritual elements.

  3. Integrated model of insulin and glucose kinetics describing both hepatic glucose and pancreatic insulin regulation

    DEFF Research Database (Denmark)

    Erlandsen, Mogens; Martinussen, Christoffer; Gravholt, Claus Højbjerg

    2018-01-01

    AbstractBackground and objectives Modeling of glucose kinetics has to a large extent been based on models with plasma insulin as a known forcing function. Furthermore, population-based statistical methods for parameter estimation in these models have mainly addressed random inter-individual varia......AbstractBackground and objectives Modeling of glucose kinetics has to a large extent been based on models with plasma insulin as a known forcing function. Furthermore, population-based statistical methods for parameter estimation in these models have mainly addressed random inter......-individual variations and not intra-individual variations in the parameters. Here we present an integrated whole-body model of glucose and insulin kinetics which extends the well-known two-compartment glucose minimal model. The population-based estimation technique allow for quantification of both random inter......- and intra-individual variation in selected parameters using simultaneous data series on glucose and insulin. Methods We extend the two-compartment glucose model into a whole-body model for both glucose and insulin using a simple model for the pancreas compartment which includes feedback of glucose on both...

  4. Modelling qualitative knowledge for strategic river management

    NARCIS (Netherlands)

    Janssen, Judith

    2009-01-01

    In decision making processes on strategic river management, use of models is not as great as the research efforts in the field of model application might suggest they could be. Both the fact that the development of many models remains restricted to readily available data and pre-existing models,

  5. Selection of heat transfer model for describing short-pulse laser heating silica-based sensor

    International Nuclear Information System (INIS)

    Hao Xiangnan; Nie Jinsong; Li Hua; Bian Jintian

    2012-01-01

    The fundamental equations of Fourier heat transfer model and non-Fourier heat transfer model were numerically solved, with the finite difference method. The relative changes between temperature curves of the two heat transfer models were analyzed under laser irradiation with different pulse widths of 10 ns, 1 ns, 100 ps, 10 ps. The impact of different thermal relaxation time on non-Fourier model results was discussed. For pulses of pulse width less than or equal to 100 ps irradiating silicon material, the surface temperature increases slowly and carrier effect happens, which the non-Fourier model can reflect properly. As for general material, when the pulse width is less than or equal to the thermal relaxation time of material, carrier effect occurs. In this case, the non-Fourier model should be used. (authors)

  6. Non-linear modelling to describe lactation curve in Gir crossbred cows

    Directory of Open Access Journals (Sweden)

    Yogesh C. Bangar

    2017-02-01

    Full Text Available Abstract Background The modelling of lactation curve provides guidelines in formulating farm managerial practices in dairy cows. The aim of the present study was to determine the suitable non-linear model which most accurately fitted to lactation curves of five lactations in 134 Gir crossbred cows reared in Research-Cum-Development Project (RCDP on Cattle farm, MPKV (Maharashtra. Four models viz. gamma-type function, quadratic model, mixed log function and Wilmink model were fitted to each lactation separately and then compared on the basis of goodness of fit measures viz. adjusted R2, root mean square error (RMSE, Akaike’s Informaion Criteria (AIC and Bayesian Information Criteria (BIC. Results In general, highest milk yield was observed in fourth lactation whereas it was lowest in first lactation. Among the models investigated, mixed log function and gamma-type function provided best fit of the lactation curve of first and remaining lactations, respectively. Quadratic model gave least fit to lactation curve in almost all lactations. Peak yield was observed as highest and lowest in fourth and first lactation, respectively. Further, first lactation showed highest persistency but relatively higher time to achieve peak yield than other lactations. Conclusion Lactation curve modelling using gamma-type function may be helpful to setting the management strategies at farm level, however, modelling must be optimized regularly before implementing them to enhance productivity in Gir crossbred cows.

  7. Fractional single-phase-lagging heat conduction model for describing anomalous diffusion

    Directory of Open Access Journals (Sweden)

    T.N. Mishra

    2016-03-01

    Full Text Available The fractional single-phase-lagging (FSPL heat conduction model is obtained by combining scalar time fractional conservation equation to the single-phase-lagging (SPL heat conduction model. Based on the FSPL heat conduction model, anomalous diffusion within a finite thin film is investigated. The effect of different parameters on solution has been observed and studied the asymptotic behavior of the FSPL model. The analytical solution is obtained using Laplace transform method. The whole analysis is presented in dimensionless form. Numerical examples of particular interest have been studied and discussed in details.

  8. Steady shear rate rheology of suspensions, as described by the gaint floc model

    NARCIS (Netherlands)

    Stein, H.N.; Laven, J.

    2001-01-01

    The break-down of a particle network by shear is described as the development of shear planes: a region able to withstand low shear stresses may break down under a larger stress; thus with increasing shear stress and shear rate, the mutual distance (A) between successive shear planes decreases

  9. Using a Model to Describe Students' Inductive Reasoning in Problem Solving

    Science.gov (United States)

    Canadas, Maria C.; Castro, Encarnacion; Castro, Enrique

    2009-01-01

    Introduction: We present some aspects of a wider investigation (Canadas, 2007), whose main objective is to describe and characterize inductive reasoning used by Spanish students in years 9 and 10 when they work on problems that involved linear and quadratic sequences. Method: We produced a test composed of six problems with different…

  10. Modeling with Young Students--Quantitative and Qualitative.

    Science.gov (United States)

    Bliss, Joan; Ogborn, Jon; Boohan, Richard; Brosnan, Tim; Mellar, Harvey; Sakonidis, Babis

    1999-01-01

    A project created tasks and tools to investigate quality and nature of 11- to 14-year-old pupils' reasoning with quantitative and qualitative computer-based modeling tools. Tasks and tools were used in two innovative modes of learning: expressive, where pupils created their own models, and exploratory, where pupils investigated an expert's model.…

  11. Qualitative Analysis of Integration Adapter Modeling

    OpenAIRE

    Ritter, Daniel; Holzleitner, Manuel

    2015-01-01

    Integration Adapters are a fundamental part of an integration system, since they provide (business) applications access to its messaging channel. However, their modeling and configuration remain under-represented. In previous work, the integration control and data flow syntax and semantics have been expressed in the Business Process Model and Notation (BPMN) as a semantic model for message-based integration, while adapter and the related quality of service modeling were left for further studi...

  12. EMPIRICAL MODELS FOR DESCRIBING FIRE BEHAVIOR IN BRAZILIAN COMMERCIAL EUCALYPT PLANTATIONS

    Directory of Open Access Journals (Sweden)

    Benjamin Leonardo Alves White

    2016-12-01

    Full Text Available Modeling forest fire behavior is an important task that can be used to assist in fire prevention and suppression operations. However, according to previous studies, the existing common worldwide fire behavior models used do not correctly estimate the fire behavior in Brazilian commercial hybrid eucalypt plantations. Therefore, this study aims to build new empirical models to predict the fire rate of spread, flame length and fuel consumption for such vegetation. To meet these objectives, 105 laboratory experimental burns were done, where the main fuel characteristics and weather variables that influence fire behavior were controlled and/or measured in each experiment. Dependent and independent variables were fitted through multiple regression analysis. The fire rate of spread proposed model is based on the wind speed, fuel bed bulk density and 1-h dead fuel moisture content (r2 = 0.86; the flame length model is based on the fuel bed depth, 1-h dead fuel moisture content and wind speed (r2 = 0.72; the fuel consumption proposed model has the 1-h dead fuel moisture, fuel bed bulk density and 1-h dead dry fuel load as independent variables (r2= 0.80. These models were used to develop a new fire behavior software, the “Eucalyptus Fire Safety System”.

  13. The Atkinson-Shiffrin model is ill-defined and does not correctly describe the Murdock free recall data

    OpenAIRE

    Tarnow, Dr. Eugen

    2009-01-01

    The Atkinson-Shiffrin (1968) model, the de facto standard model of short term memory cited thousands of times, fits the characteristically bowed free recall curves from Murdock (1962) well. However, it is long overdue to note that it is not a theoretically convincing explanation and that it does not fit all of the experimental relationships in the Murdock data. To obtain a qualitatively correct fit of the bowing I show that four model concepts have to work together. “Long term memory” is ...

  14. A simple geometrical model describing shapes of soap films suspended on two rings

    Science.gov (United States)

    Herrmann, Felix J.; Kilvington, Charles D.; Wildenberg, Rebekah L.; Camacho, Franco E.; Walecki, Wojciech J.; Walecki, Peter S.; Walecki, Eve S.

    2016-09-01

    We measured and analysed the stability of two types of soap films suspended on two rings using the simple conical frusta-based model, where we use common definition of conical frustum as a portion of a cone that lies between two parallel planes cutting it. Using frusta-based we reproduced very well-known results for catenoid surfaces with and without a central disk. We present for the first time a simple conical frusta based spreadsheet model of the soap surface. This very simple, elementary, geometrical model produces results surprisingly well matching the experimental data and known exact analytical solutions. The experiment and the spreadsheet model can be used as a powerful teaching tool for pre-calculus and geometry students.

  15. How well do basic models describe the turbidity currents coming down Monterey and Congo Canyon?

    Science.gov (United States)

    Cartigny, M.; Simmons, S.; Heerema, C.; Xu, J. P.; Azpiroz, M.; Clare, M. A.; Cooper, C.; Gales, J. A.; Maier, K. L.; Parsons, D. R.; Paull, C. K.; Sumner, E. J.; Talling, P.

    2017-12-01

    Turbidity currents rival rivers in their global capacity to transport sediment and organic carbon. Furthermore, turbidity currents break submarine cables that now transport >95% of our global data traffic. Accurate turbidity current models are thus needed to quantify their transport capacity and to predict the forces exerted on seafloor structures. Despite this need, existing numerical models are typically only calibrated with scaled-down laboratory measurements due to the paucity of direct measurements of field-scale turbidity currents. This lack of calibration thus leaves much uncertainty in the validity of existing models. Here we use the most detailed observations of turbidity currents yet acquired to validate one of the most fundamental models proposed for turbidity currents, the modified Chézy model. Direct measurements on which the validation is based come from two sites that feature distinctly different flow modes and grain sizes. The first are from the multi-institution Coordinated Canyon Experiment (CCE) in Monterey Canyon, California. An array of six moorings along the canyon axis captured at least 15 flow events that lasted up to hours. The second is the deep-sea Congo Canyon, where 10 finer grained flows were measured by a single mooring, each lasting several days. Moorings captured depth-resolved velocity and suspended sediment concentration at high resolution (turbidity currents; the modified Chézy model. This basic model has been very useful for river studies over the past 200 years, as it provides a rapid estimate of how flow velocity varies with changes in river level and energy slope. Chézy-type models assume that the gravitational force of the flow equals the friction of the river-bed. Modified Chézy models have been proposed for turbidity currents. However, the absence of detailed measurements of friction and sediment concentration within full-scale turbidity currents has forced modellers to make rough assumptions for these parameters. Here

  16. A Bayesian method for construction of Markov models to describe dynamics on various time-scales.

    Science.gov (United States)

    Rains, Emily K; Andersen, Hans C

    2010-10-14

    The dynamics of many biological processes of interest, such as the folding of a protein, are slow and complicated enough that a single molecular dynamics simulation trajectory of the entire process is difficult to obtain in any reasonable amount of time. Moreover, one such simulation may not be sufficient to develop an understanding of the mechanism of the process, and multiple simulations may be necessary. One approach to circumvent this computational barrier is the use of Markov state models. These models are useful because they can be constructed using data from a large number of shorter simulations instead of a single long simulation. This paper presents a new Bayesian method for the construction of Markov models from simulation data. A Markov model is specified by (τ,P,T), where τ is the mesoscopic time step, P is a partition of configuration space into mesostates, and T is an N(P)×N(P) transition rate matrix for transitions between the mesostates in one mesoscopic time step, where N(P) is the number of mesostates in P. The method presented here is different from previous Bayesian methods in several ways. (1) The method uses Bayesian analysis to determine the partition as well as the transition probabilities. (2) The method allows the construction of a Markov model for any chosen mesoscopic time-scale τ. (3) It constructs Markov models for which the diagonal elements of T are all equal to or greater than 0.5. Such a model will be called a "consistent mesoscopic Markov model" (CMMM). Such models have important advantages for providing an understanding of the dynamics on a mesoscopic time-scale. The Bayesian method uses simulation data to find a posterior probability distribution for (P,T) for any chosen τ. This distribution can be regarded as the Bayesian probability that the kinetics observed in the atomistic simulation data on the mesoscopic time-scale τ was generated by the CMMM specified by (P,T). An optimization algorithm is used to find the most

  17. Transport in semiconductor nanowire superlattices described by coupled quantum mechanical and kinetic models.

    Science.gov (United States)

    Alvaro, M; Bonilla, L L; Carretero, M; Melnik, R V N; Prabhakar, S

    2013-08-21

    In this paper we develop a kinetic model for the analysis of semiconductor superlattices, accounting for quantum effects. The model consists of a Boltzmann-Poisson type system of equations with simplified Bhatnagar-Gross-Krook collisions, obtained from the general time-dependent Schrödinger-Poisson model using Wigner functions. This system for superlattice transport is supplemented by the quantum mechanical part of the model based on the Ben-Daniel-Duke form of the Schrödinger equation for a cylindrical superlattice of finite radius. The resulting energy spectrum is used to characterize the Fermi-Dirac distribution that appears in the Bhatnagar-Gross-Krook collision, thereby coupling the quantum mechanical and kinetic parts of the model. The kinetic model uses the dispersion relation obtained by the generalized Kronig-Penney method, and allows us to estimate radii of quantum wire superlattices that have the same miniband widths as in experiments. It also allows us to determine more accurately the time-dependent characteristics of superlattices, in particular their current density. Results, for several experimentally grown superlattices, are discussed in the context of self-sustained coherent oscillations of the current density which are important in an increasing range of current and potential applications.

  18. An empirical model to describe performance degradation for warranty abuse detection in portable electronics

    International Nuclear Information System (INIS)

    Oh, Hyunseok; Choi, Seunghyuk; Kim, Keunsu; Youn, Byeng D.; Pecht, Michael

    2015-01-01

    Portable electronics makers have introduced liquid damage indicators (LDIs) into their products to detect warranty abuse caused by water damage. However, under certain conditions, these indicators can exhibit inconsistencies in detecting liquid damage. This study is motivated by the fact that the reliability of LDIs in portable electronics is suspected. In this paper, first, the scheme of life tests is devised for LDIs in conjunction with a robust color classification rule. Second, a degradation model is proposed by considering the two physical mechanisms—(1) phase change from vapor to water and (2) water transport in the porous paper—for LDIs. Finally, the degradation model is validated with additional tests using actual smartphone sets subjected to the thermal cycling of −15 °C to 25 °C and the relative humidity of 95%. By employing the innovative life testing scheme and the novel performance degradation model, it is expected that the performance of LDIs for a particular application can be assessed quickly and accurately. - Highlights: • Devise an efficient scheme of life testing for a warranty abuse detector in portable electronics. • Develop a performance degradation model for the warranty abuse detector used in portable electronics. • Validate the performance degradation model with life tests of actual smartphone sets. • Help make a decision on warranty service in portable electronics manufacturers

  19. A model, describing the influence of water management alternatives on dike stability

    Directory of Open Access Journals (Sweden)

    J. W. M. Lambert

    2015-11-01

    Full Text Available The awareness is rising that economic effects of Land Subsidence are high. Nevertheless, quantifying these economic losses is difficult and, as far as known, not yet done in a sophisticated way. Also, to be able to decide about future strategies, for example to avoid or decrease subsidence, it is necessary to know the financial consequences of measures and possible solutions. As a first step to quantify these economic effects, a MODFLOW-SCR (coupled MODFLOW-Settlements model is coupled with the model DAM. Based on the local stratigraphy, the shape and composition of the existing dike or levee, the level of the surface water and the surface level, macro-stability of the dike is calculated and – if the dike does not meet the required stability – adaptions are proposed. The model enables to separate effects that are caused by sea-level rise and the effects of subsidence. Coupling the DAM model with an economic model to calculate costs of these adaptions is under construction.

  20. Integrated compartmental model for describing the transport of solute in a fractured porous medium. [FRACPORT

    Energy Technology Data Exchange (ETDEWEB)

    DeAngelis, D.L.; Yeh, G.T.; Huff, D.D.

    1984-10-01

    This report documents a model, FRACPORT, that simulates the transport of a solute through a fractured porous matrix. The model should be useful in analyzing the possible transport of radionuclides from shallow-land burial sites in humid environments. The use of the model is restricted to transport through saturated zones. The report first discusses the general modeling approach used, which is based on the Integrated Compartmental Method. The basic equations of solute transport are then presented. The model, which assumes a known water velocity field, solves these equations on two different time scales; one related to rapid transport of solute along fractures and the other related to slower transport through the porous matrix. FRACPORT is validated by application to a simple example of fractured porous medium transport that has previously been analyzed by other methods. Then its utility is demonstrated in analyzing more complex cases of pulses of solute into a fractured matrix. The report serves as a user's guide to FRACPORT. A detailed description of data input, along with a listing of input for a sample problem, is provided. 16 references, 18 figures, 3 tables.

  1. Modified VMD model with correct analytic properties for describing electromagnetic structure of He4 nucleus

    International Nuclear Information System (INIS)

    Dubnicka, S.; Lucan, L.

    1988-12-01

    A new phenomenological model for electromagnetic (e.m.) form factor (ff) of He 4 nucleus is presented, which is based on a modification of the well proved in e.m. interactions of hadrons vector-meson-dominance (VMD) model by means of an incorporation of correct He 4 ff analytic properties, nonzero vector-meson widths and the right power asymptotic behaviour predicted by the quark model. It reproduces the existing experimental information on He 4 e.m. ff in the space-like region quite well. Furthermore, couplings of all well established isoscalar vector mesons with J pc = 1 -- to He 4 nucleus are evaluated as a result of the analysis and the time-like region behaviour of He 4 e.m. ff is predicted. As a consequence of the latter the total cross section of e + e - → He 4 He-bar 4 process is calculated for the first time. (author). 17 refs, 3 figs

  2. Comparison of two mathematical models for describing heat-induced cell killing

    International Nuclear Information System (INIS)

    Roti Roti, J.L.; Henle, K.J.

    1980-01-01

    A computer-based minimization algorithm is utilized to obtain the optimum fits of two models to hyperthermic cell killing data. The models chosen are the multitarget, single-hit equation, which is in general use, and the linear-quadratic equation, which has been applied to cell killing by ionizing irradiation but not to heat-induced cell killing. The linear-quadratic equation fits hyperthermic cell killing data as well as the multitarget, single-hit equation. Both parameters of the linear-quadratic equation obey the Arrhenius law, whereas only one of the two parameters of the multitarget, single-hit equation obeys the Arrhenius law. Thus the linear-quadratic function can completely define cell killing as a function of both time and temperature. In addition, the linear-quadratic model will provide a simplified approach to the study of the synergism between heat and X irradiation

  3. Benchmarking of numerical models describing the dispersion of radionuclides in the Arctic Seas

    DEFF Research Database (Denmark)

    Scott, E.M.; Gurbutt, P.; Harms, I.

    1997-01-01

    As part of the International Arctic Seas Assessment Project (IASAP) of the International Atomic Energy Agency (IAEA), a working group was created to model the dispersal and transfer of radionuclides released from radioactive waste disposed of in the Kara Sea. The objectives of this group are: (1......) development of realistic and reliable assessment models for the dispersal of radioactive contaminants both within, and from, the Arctic ocean; and (2) evaluation of the contributions of different transfer mechanisms to contaminant dispersal and hence, ultimately, to the risks to human health and environment...

  4. A gauge model describing N relativistic particles bound by linear forces

    International Nuclear Information System (INIS)

    Filippov, A.T.

    1988-01-01

    A relativistic model of N particles bound by linear forces is obtained by applying the gauging procedure to the linear canonical symmteries of a simple (rudimentary) nonrelativistic N-particle Lagrangian extended to relativistic phase space. The new (gauged) Lagrangian is formally Poincare invariant, the Hamiltonian is a linear combination of first-class constraints which are closed with respect to Pisson brackets and generate the localized canonical symmteries. The gauge potentials appear as the Lagrange multipliers of the constraints. Gauge fixing and quantization of the model are also briefly discussed. 11 refs

  5. Feasibility study for a plasticity model to describe the transient thermomechanical behavior of Zircaloy. Final report

    International Nuclear Information System (INIS)

    Valanis, K.C.

    1979-11-01

    The conceptual framework of the endochronic theory is described and a summary of its capabilities, as well as past and potential applications to the mechanical response of metals to general histories of deformation, temperature, and radiation is given. The purely mechanical part of the theory is developed on the basis of the concept of intrinsic time which serves to incorporate in a unified and concise fashion the effects of strain history and strain rate on the stress response. The effects of temperature are introduced by means of the theory of deformation kinetics through its relation to the internal variable theory of irreversible thermodynamics. As a result, physically sound formulae are developed which account for the effect of temperature history on the stress response. An approach to describing irradiation effects is briefly discussed. More research would be needed to define appropriate constitutive representations for Zircaloy. The endochronic theory is also looked at from a numerical analysis viewpoint of future applications to problems of practical interest. In appendix B a first cut attempt has been made to assess the computational efficiencies of material constitutive equation approaches

  6. q-deformed Einstein's model to describe specific heat of solid

    Science.gov (United States)

    Guha, Atanu; Das, Prasanta Kumar

    2018-04-01

    Realistic phenomena can be described more appropriately using generalized canonical ensemble, with proper parameter sets involved. We have generalized the Einstein's theory for specific heat of solid in Tsallis statistics, where the temperature fluctuation is introduced into the theory via the fluctuation parameter q. At low temperature the Einstein's curve of the specific heat in the nonextensive Tsallis scenario exactly lies on the experimental data points. Consequently this q-modified Einstein's curve is found to be overlapping with the one predicted by Debye. Considering only the temperature fluctuation effect(even without considering more than one mode of vibration is being triggered) we found that the CV vs T curve is as good as obtained by considering the different modes of vibration as suggested by Debye. Generalizing the Einstein's theory in Tsallis statistics we found that a unique value of the Einstein temperature θE along with a temperature dependent deformation parameter q(T) , can well describe the phenomena of specific heat of solid i.e. the theory is equivalent to Debye's theory with a temperature dependent θD.

  7. The operator model as a framework of research on errors and temporal, qualitative and analogical reasoning

    International Nuclear Information System (INIS)

    Decortis, F.; Drozdowicz, B.; Masson, M.

    1990-01-01

    In this paper the needs and requirements for developing a cognitive model of a human operator are discussed and the computer architecture, currently being developed, is described. Given the approach taken, namely the division of the problem into specialised tasks within an area and using the architecture chosen, it is possible to build independently several cognitive and psychological models such as errors and stress models, as well as models of temporal, qualitative and an analogical reasoning. (author)

  8. Using Rouse-Fowler model to describe radiation-induced electrical conductivity of nanocomposite materials

    Science.gov (United States)

    Dyuryagina, N. S.; Yalovets, A. P.

    2017-05-01

    Using the Rouse-Fowler (RF) model this work studies the radiation-induced electrical conductivity of a polymer nanocomposite material with spherical nanoparticles against the intensity and exposure time of gamma-ray, concentration and size of nanoparticles. The research has found the energy distribution of localized statesinduced by nanoparticles. The studies were conducted on polymethylmethacrylate (PMMA) with CdS nanoparticles.

  9. Kinetic model describing the UV/H2O2 photodegradation of phenol from water

    Directory of Open Access Journals (Sweden)

    Rubio-Clemente Ainhoa

    2017-01-01

    Full Text Available A kinetic model for phenol transformation through the UV/H2O2 system was developed and validated. The model includes the pollutant decomposition by direct photolysis and HO•, HO2• and O2 •- oxidation. HO• scavenging effects of CO3 2-, HCO3 -, SO4 2- and Cl- were also considered, as well as the pH changes as the process proceeds. Additionally, the detrimental action of the organic matter and reaction intermediates in shielding UV and quenching HO• was incorporated. It was observed that the model can accurately predict phenol abatement using different H2O2/phenol mass ratios (495, 228 and 125, obtaining an optimal H2O2/phenol ratio of 125, leading to a phenol removal higher than 95% after 40 min of treatment, where the main oxidation species was HO•. The developed model could be relevant for calculating the optimal level of H2O2 efficiently degrading the pollutant of interest, allowing saving in costs and time.

  10. CAN A NANOFLARE MODEL OF EXTREME-ULTRAVIOLET IRRADIANCES DESCRIBE THE HEATING OF THE SOLAR CORONA?

    Energy Technology Data Exchange (ETDEWEB)

    Tajfirouze, E.; Safari, H. [Department of Physics, University of Zanjan, P.O. Box 45195-313, Zanjan (Iran, Islamic Republic of)

    2012-01-10

    Nanoflares, the basic units of impulsive energy release, may produce much of the solar background emission. Extrapolation of the energy frequency distribution of observed microflares, which follows a power law to lower energies, can give an estimation of the importance of nanoflares for heating the solar corona. If the power-law index is greater than 2, then the nanoflare contribution is dominant. We model a time series of extreme-ultraviolet emission radiance as random flares with a power-law exponent of the flare event distribution. The model is based on three key parameters: the flare rate, the flare duration, and the power-law exponent of the flare intensity frequency distribution. We use this model to simulate emission line radiance detected in 171 A, observed by Solar Terrestrial Relation Observatory/Extreme-Ultraviolet Imager and Solar Dynamics Observatory/Atmospheric Imaging Assembly. The observed light curves are matched with simulated light curves using an Artificial Neural Network, and the parameter values are determined across the active region, quiet Sun, and coronal hole. The damping rate of nanoflares is compared with the radiative losses cooling time. The effect of background emission, data cadence, and network sensitivity on the key parameters of the model is studied. Most of the observed light curves have a power-law exponent, {alpha}, greater than the critical value 2. At these sites, nanoflare heating could be significant.

  11. Exponential law as a more compatible model to describe orbits of planetary systems

    Directory of Open Access Journals (Sweden)

    M Saeedi

    2012-12-01

    Full Text Available   According to the Titus-Bode law, orbits of planets in the solar system obey a geometric progression. Many investigations have been launched to improve this law. In this paper, we apply square and exponential models to planets of solar system, moons of planets, and some extra solar systems, and compare them with each other.

  12. Application of the International Water Association activated sludge models to describe aerobic sludge digestion.

    Science.gov (United States)

    Ghorbani, M; Eskicioglu, C

    2011-12-01

    Batch and semi-continuous flow aerobic digesters were used to stabilize thickened waste-activated sludge at different initial conditions and mean solids retention times. Under dynamic conditions, total suspended solids, volatile suspended solids (VSS) and total and particulate chemical oxygen demand (COD and PCOD) were monitored in the batch reactors and effluent from the semi-continuous flow reactors. Activated Sludge Model (ASM) no. 1 and ASM no. 3 were applied to measured data (calibration data set) to evaluate the consistency and performances of models at different flow regimes for digester COD and VSS modelling. The results indicated that both ASM1 and ASM3 predicted digester COD, VSS and PCOD concentrations well (R2, Ra2 > or = 0.93). Parameter estimation concluded that compared to ASM1, ASM3 parameters were more consistent across different batch and semi-continuous flow runs with different operating conditions. Model validation on a data set independent from the calibration data successfully predicted digester COD (R2 = 0.88) and VSS (R2 = 0.94) concentrations by ASM3, while ASM1 overestimated both reactor COD (R2 = 0.74) and VSS concentrations (R2 = 0.79) after 15 days of aerobic batch digestion.

  13. Predictive model to describe water migration in cellular solid foods during storage

    NARCIS (Netherlands)

    Voogt, J.A.; Hirte, A.; Meinders, M.B.J.

    2011-01-01

    BACKGROUND: Water migration in cellular solid foods during storage causes loss of crispness. To improve crispness retention, physical understanding of this process is needed. Mathematical models are suitable tools to gain this physical knowledge. RESULTS: Water migration in cellular solid foods

  14. Predictive model to describe water migration in cellular solid foods during storage

    NARCIS (Netherlands)

    Voogt, J.A.; Hirte, A.; Meinders, M.B.J.

    2011-01-01

    Background: Water migration in cellular solid foods during storage causes loss of crispness. To improve crispness retention, physical understanding of this process is needed. Mathematical models are suitable tools to gain this physical knowledge. Results: Water migration in cellular solid foods

  15. A vapour bubble collapse model to describe the fragmentation of low-melting materials

    International Nuclear Information System (INIS)

    Benz, R.; Schober, P.

    1977-11-01

    By means of a model, the fragmentation of a hot melt of metal in consequence of collapsing vapour-bubbles is investigated. In particular the paper deals with the development of the physical model-ideas for calculation of the temperature of contact that adjusts between the temperature of the melt and the coolant, of the waiting-time until bubble-nucleation occurs and of the maximal obtainable vapour-bubble-radius in dependence of the coolant-temperature. After that follows the description of the computing-program belonging to this model and of the results of an extensive parameter-study. The study examined the influence of the temperature of melt and coolant, the melted mass, the nucleation-site-density, the average maximum bubble-radius, the duration of film-breakdown and the coefficient of heat-transition. The calculation of the process of fragmentation turns out to be according to expectation, whereas the duration of this process seems to be somewhat too long. The dependence of the surface-enlargement on the subcooling of the water-bath and the initial temperature of the melt is not yet reproduced satisfactorily by the model. The reasons for this are the temperature-increase of the water-bath as well as the fact that the coupling of heat-flux-density and nucleation-site-density are not taken into consideration. Further improvement of the model is necessary and may improve the results in the sense of the experimental observations. (orig.) [de

  16. Atomic-orbital expansion model for describing ion-atom collisions at intermediate and low energies

    International Nuclear Information System (INIS)

    Lin, C.D.; Fritsch, W.

    1983-01-01

    In the description of inelastic processes in ion-atom collisions at moderate energies, the semiclassical close-coupling method is well established as the standard method. Ever since the pioneering work on H + + H in the early 60's, the standard procedure is to expand the electronic wavefunction in terms of molecular orbitals (MO) or atomic orbitals (AO) for describing collisions at, respectively, low or intermediate velocities. It has been recognized since early days that traveling orbitals are needed in the expansions in order to represent the asymptotic states in the collisions correctly. While the adoption of such traveling orbitals presents no conceptual difficulties for expansions using atomic orbitals, the situation for molecular orbitals is less clear. In recent years, various forms of traveling MO's have been proposed, but conflicting results for several well-studied systems have been reported

  17. A physical model describing the interaction of nuclear transport receptors with FG nucleoporin domain assemblies.

    Science.gov (United States)

    Zahn, Raphael; Osmanović, Dino; Ehret, Severin; Araya Callis, Carolina; Frey, Steffen; Stewart, Murray; You, Changjiang; Görlich, Dirk; Hoogenboom, Bart W; Richter, Ralf P

    2016-04-08

    The permeability barrier of nuclear pore complexes (NPCs) controls bulk nucleocytoplasmic exchange. It consists of nucleoporin domains rich in phenylalanine-glycine motifs (FG domains). As a bottom-up nanoscale model for the permeability barrier, we have used planar films produced with three different end-grafted FG domains, and quantitatively analyzed the binding of two different nuclear transport receptors (NTRs), NTF2 and Importin β, together with the concomitant film thickness changes. NTR binding caused only moderate changes in film thickness; the binding isotherms showed negative cooperativity and could all be mapped onto a single master curve. This universal NTR binding behavior - a key element for the transport selectivity of the NPC - was quantitatively reproduced by a physical model that treats FG domains as regular, flexible polymers, and NTRs as spherical colloids with a homogeneous surface, ignoring the detailed arrangement of interaction sites along FG domains and on the NTR surface.

  18. A stochastic Markov chain model to describe lung cancer growth and metastasis.

    Directory of Open Access Journals (Sweden)

    Paul K Newton

    Full Text Available A stochastic Markov chain model for metastatic progression is developed for primary lung cancer based on a network construction of metastatic sites with dynamics modeled as an ensemble of random walkers on the network. We calculate a transition matrix, with entries (transition probabilities interpreted as random variables, and use it to construct a circular bi-directional network of primary and metastatic locations based on postmortem tissue analysis of 3827 autopsies on untreated patients documenting all primary tumor locations and metastatic sites from this population. The resulting 50 potential metastatic sites are connected by directed edges with distributed weightings, where the site connections and weightings are obtained by calculating the entries of an ensemble of transition matrices so that the steady-state distribution obtained from the long-time limit of the Markov chain dynamical system corresponds to the ensemble metastatic distribution obtained from the autopsy data set. We condition our search for a transition matrix on an initial distribution of metastatic tumors obtained from the data set. Through an iterative numerical search procedure, we adjust the entries of a sequence of approximations until a transition matrix with the correct steady-state is found (up to a numerical threshold. Since this constrained linear optimization problem is underdetermined, we characterize the statistical variance of the ensemble of transition matrices calculated using the means and variances of their singular value distributions as a diagnostic tool. We interpret the ensemble averaged transition probabilities as (approximately normally distributed random variables. The model allows us to simulate and quantify disease progression pathways and timescales of progression from the lung position to other sites and we highlight several key findings based on the model.

  19. Generating quantitative models describing the sequence specificity of biological processes with the stabilized matrix method

    Directory of Open Access Journals (Sweden)

    Sette Alessandro

    2005-05-01

    Full Text Available Abstract Background Many processes in molecular biology involve the recognition of short sequences of nucleic-or amino acids, such as the binding of immunogenic peptides to major histocompatibility complex (MHC molecules. From experimental data, a model of the sequence specificity of these processes can be constructed, such as a sequence motif, a scoring matrix or an artificial neural network. The purpose of these models is two-fold. First, they can provide a summary of experimental results, allowing for a deeper understanding of the mechanisms involved in sequence recognition. Second, such models can be used to predict the experimental outcome for yet untested sequences. In the past we reported the development of a method to generate such models called the Stabilized Matrix Method (SMM. This method has been successfully applied to predicting peptide binding to MHC molecules, peptide transport by the transporter associated with antigen presentation (TAP and proteasomal cleavage of protein sequences. Results Herein we report the implementation of the SMM algorithm as a publicly available software package. Specific features determining the type of problems the method is most appropriate for are discussed. Advantageous features of the package are: (1 the output generated is easy to interpret, (2 input and output are both quantitative, (3 specific computational strategies to handle experimental noise are built in, (4 the algorithm is designed to effectively handle bounded experimental data, (5 experimental data from randomized peptide libraries and conventional peptides can easily be combined, and (6 it is possible to incorporate pair interactions between positions of a sequence. Conclusion Making the SMM method publicly available enables bioinformaticians and experimental biologists to easily access it, to compare its performance to other prediction methods, and to extend it to other applications.

  20. Formulation and integration of constitutive models describing large deformations in thermoplasticity and thermoviscoplasticity

    International Nuclear Information System (INIS)

    Jansohn, W.

    1997-10-01

    This report deals with the formulation and numerical integration of constitutive models in the framework of finite deformation thermomechanics. Based on the concept of dual variables, plasticity and viscoplasticity models exhibiting nonlinear kinematic hardening as well as nonlinear isotropic hardening rules are presented. Care is taken that the evolution equations governing the hardening response fulfill the intrinsic dissipation inequality in every admissible process. In view of the development of an efficient numerical integration procedure, simplified versions of these constitutive models are supposed. In these versions, the thermoelastic strains are assumed to be small and a simplified kinematic hardening rule is considered. Additionally, in view of an implementation into the ABAQUS finite element code, the elasticity law is approximated by a hypoelasticity law. For the simplified onstitutive models, an implicit time-integration algorithm is developed. First, in order to obtain a numerical objective integration scheme, use is made of the HUGHES-WINGET-Algorithm. In the resulting system of ordinary differential equations, it can be distinguished between three differential operators representing different physical effects. The structure of this system of differential equations allows to apply an operator split scheme, which leads to an efficient integration scheme for the constitutive equations. By linearizing the integration algorithm the consistent tangent modulus is derived. In this way, the quadratic convergence of Newton's method used to solve the basic finite element equations (i.e. the finite element discretization of the governing thermomechanical field equations) is preserved. The resulting integration scheme is implemented as a user subroutine UMAT in ABAQUS. The properties of the applied algorithm are first examined by test calculations on a single element under tension-compression-loading. For demonstrating the capabilities of the constitutive theory

  1. A stochastic Markov chain model to describe lung cancer growth and metastasis.

    Science.gov (United States)

    Newton, Paul K; Mason, Jeremy; Bethel, Kelly; Bazhenova, Lyudmila A; Nieva, Jorge; Kuhn, Peter

    2012-01-01

    A stochastic Markov chain model for metastatic progression is developed for primary lung cancer based on a network construction of metastatic sites with dynamics modeled as an ensemble of random walkers on the network. We calculate a transition matrix, with entries (transition probabilities) interpreted as random variables, and use it to construct a circular bi-directional network of primary and metastatic locations based on postmortem tissue analysis of 3827 autopsies on untreated patients documenting all primary tumor locations and metastatic sites from this population. The resulting 50 potential metastatic sites are connected by directed edges with distributed weightings, where the site connections and weightings are obtained by calculating the entries of an ensemble of transition matrices so that the steady-state distribution obtained from the long-time limit of the Markov chain dynamical system corresponds to the ensemble metastatic distribution obtained from the autopsy data set. We condition our search for a transition matrix on an initial distribution of metastatic tumors obtained from the data set. Through an iterative numerical search procedure, we adjust the entries of a sequence of approximations until a transition matrix with the correct steady-state is found (up to a numerical threshold). Since this constrained linear optimization problem is underdetermined, we characterize the statistical variance of the ensemble of transition matrices calculated using the means and variances of their singular value distributions as a diagnostic tool. We interpret the ensemble averaged transition probabilities as (approximately) normally distributed random variables. The model allows us to simulate and quantify disease progression pathways and timescales of progression from the lung position to other sites and we highlight several key findings based on the model.

  2. A qualitative evaluation approach for energy system modelling frameworks

    DEFF Research Database (Denmark)

    Wiese, Frauke; Hilpert, Simon; Kaldemeyer, Cord

    2018-01-01

    properties define how useful it is in regard to the existing challenges. For energy system models, evaluation methods exist, but we argue that many decisions upon properties are rather made on the model generator or framework level. Thus, this paper presents a qualitative approach to evaluate frameworks...

  3. The Use of Modelling for Theory Building in Qualitative Analysis

    Science.gov (United States)

    Briggs, Ann R. J.

    2007-01-01

    The purpose of this article is to exemplify and enhance the place of modelling as a qualitative process in educational research. Modelling is widely used in quantitative research as a tool for analysis, theory building and prediction. Statistical data lend themselves to graphical representation of values, interrelationships and operational…

  4. Graphical means for inspecting qualitative models of system behaviour

    NARCIS (Netherlands)

    Bouwer, A.; Bredeweg, B.

    2010-01-01

    This article presents the design and evaluation of a tool for inspecting conceptual models of system behaviour. The basis for this research is the Garp framework for qualitative simulation. This framework includes modelling primitives, such as entities, quantities and causal dependencies, which are

  5. Accelerating transition dynamics in city regions: A qualitative modeling perspective

    NARCIS (Netherlands)

    P.J. Valkering (Pieter); Yücel, G. (Gönenç); Gebetsroither-Geringer, E. (Ernst); Markvica, K. (Karin); Meynaerts, E. (Erika); N. Frantzeskaki (Niki)

    2017-01-01

    textabstractIn this article, we take stock of the findings from conceptual and empirical work on the role of transition initiatives for accelerating transitions as input for modeling acceleration dynamics. We applied the qualitative modeling approach of causal loop diagrams to capture the dynamics

  6. Phenomenological Model Describing the Formation of Peeling Defects on Hot-Rolled Duplex Stainless Steel 2205

    Science.gov (United States)

    Yong-jun, Zhang; Hui, Zhang; Jing-tao, Han

    2017-05-01

    The chemical composition, morphology, and microstructure of peeling defects formed on the surface of sheets from steel 2205 under hot rolling are studied. The microstructure of the surface is analyzed using scanning electron and light microscopy. The zones affected are shown to contain nonmetallic inclusions of types Al2O3 and CaO - SiO2 - Al2O3 - MgO in the form of streak precipitates and to have an unfavorable content of austenite, which causes decrease in the ductility of the area. The results obtained are used to derive a five-stage phenomenological model of formation of such defects.

  7. Application of a non-equilibrium reaction model for describing horizontal well performance in foamy oil

    Energy Technology Data Exchange (ETDEWEB)

    Luigi, A.; Saputelli, B.; Carlas, M.; Canache, P.; Lopez, E. [DPVS Exploracion y Produccion (Venezuela)

    1998-12-31

    This study was designed to determine the activation energy ranges and frequency factor ranges in chemical reactions in heavy oils of the Orinoco Belt in Venezuela, in order to account for the kinetics of physical changes that occur in the morphology of gas-oil dispersion. A non-equilibrium reaction model was used to model foamy oil behaviour observed at SDZ-182 horizontal well in the Zuata field. Results showed that activation energy for the first reaction ranged from 0 to 0.01 BTU/lb-mol and frequency factor from 0.001 to 1000 l/day. For the second reaction the activation energy was 50x10{sub 3} BTU/lb-mol and the frequency factor 2.75x10{sub 1}2 l/day. The second reaction was highly sensitive to the modifications in activation energy and frequency factor. However, both the activation energy and frequency factor were independent of variations for the first reaction. In the case of the activation energy, the results showed that the high sensitivity of this parameter reflected the impact that temperature has on the representation of foamy oil behaviour. 8 refs., 2 tabs., 6 figs.

  8. SPATIAL MODELLING FOR DESCRIBING SPATIAL VARIABILITY OF SOIL PHYSICAL PROPERTIES IN EASTERN CROATIA

    Directory of Open Access Journals (Sweden)

    Igor Bogunović

    2016-06-01

    Full Text Available The objectives of this study were to characterize the field-scale spatial variability and test several interpolation methods to identify the best spatial predictor of penetration resistance (PR, bulk density (BD and gravimetric water content (GWC in the silty loam soil in Eastern Croatia. The measurements were made on a 25 x 25-m grid which created 40 individual grid cells. Soil properties were measured at the center of the grid cell deep 0-10 cm and 10-20 cm. Results demonstrated that PR and GWC displayed strong spatial dependence at 0-10 cm BD, while there was moderate and weak spatial dependence of PR, BD and GWC at depth of 10-20 cm. Semi-variogram analysis suggests that future sampling intervals for investigated parameters can be increased to 35 m in order to reduce research costs. Additionally, interpolation models recorded similar root mean square values with high predictive accuracy. Results suggest that investigated properties do not have uniform interpolation method implying the need for spatial modelling in the evaluation of these soil properties in Eastern Croatia.

  9. Describing model of empowering managers by applying structural equation modeling: A case study of universities in Ardabil

    Directory of Open Access Journals (Sweden)

    Maryam Ghahremani Germi

    2015-06-01

    Full Text Available Empowerment is still on the agenda as a management concept and has become a widely used management term in the last decade or so. The purpose of this research was describing model of empowering managers by applying structural equation modeling (SEM at Ardabil universities. Two hundred and twenty managers of Ardabil universities including chancellors, managers, and vice presidents of education, research, and studies participated in this study. Clear and challenging goals, evaluation of function, access to resources, and rewarding were investigated. The results indicated that the designed SEM for empowering managers at university reflects a good fitness level. As it stands out, the conceptual model in the society under investigation was used appropriately. Among variables, access to resources with 88 per cent of load factor was known as the affective variable. Evaluation of function containing 51 per cent of load factor was recognized to have less effect. Results of average rating show that evaluation of function and access to resources with 2.62 coefficients stand at first level. Due to this, they had great impact on managers' empowerment. The results of the analysis provided compelling evidence that model of empowering managers was desirable at Ardabil universities.

  10. A nonlinear beam model to describe the postbuckling of wide neo-Hookean beams

    Science.gov (United States)

    Lubbers, Luuk A.; van Hecke, Martin; Coulais, Corentin

    2017-09-01

    Wide beams can exhibit subcritical buckling, i.e. the slope of the force-displacement curve can become negative in the postbuckling regime. In this paper, we capture this intriguing behaviour by constructing a 1D nonlinear beam model, where the central ingredient is the nonlinearity in the stress-strain relation of the beams constitutive material. First, we present experimental and numerical evidence of a transition to subcritical buckling for wide neo-Hookean hyperelastic beams, when their width-to-length ratio exceeds a critical value of 12%. Second, we construct an effective 1D energy density by combining the Mindlin-Reissner kinematics with a nonlinearity in the stress-strain relation. Finally, we establish and solve the governing beam equations to analytically determine the slope of the force-displacement curve in the postbuckling regime. We find, without any adjustable parameters, excellent agreement between the 1D theory, experiments and simulations. Our work extends the understanding of the postbuckling of structures made of wide elastic beams and opens up avenues for the reverse-engineering of instabilities in soft and metamaterials.

  11. The modulation of galactic cosmic rays as described by a three-dimensional drift model

    International Nuclear Information System (INIS)

    Potgieter, M.S.

    1984-01-01

    An outline of the present state of knowledge about the effect of drift on the modulation of galactic cosmic rays is given. Various observations related to the reversal of the solar magnetic field polarity are discussed. Comprehensive numerical solutions of the steady-state cosmic-ray transport equation in an axially-symmetric three-dimensional heliosphere, including drift are presented. This is an extention of the continuing effort of the past six years to understand the effect and importance of drift on the transport of galactic cosmic rays in the heliosphere. A flat neutral sheet which coincides with the equatorial plane is assumed. A general method of calculating the drift velocity in the neutral sheet including that used previously by other authors is presented. The effect of changing various modulation parameters on the drift solutions are illustrated in detail. The real significance of drift is illustrated by using Gaussian input spectra on the modulation boundary. A carefully selected set of modulation parameters is used to illustrate to what extent a drift model can explain prominent observational features. It is concluded that drift is important in in the process of cosmic-ray transport and must as such be considered in all modulation studies, but that it is not overwhelmingly dominant as previously anticipated

  12. Multilevel regression models describing regional patterns of invertebrate and algal responses to urbanization across the USA

    Science.gov (United States)

    Cuffney, T.F.; Kashuba, R.; Qian, S.S.; Alameddine, I.; Cha, Y.K.; Lee, B.; Coles, J.F.; McMahon, G.

    2011-01-01

    Multilevel hierarchical regression was used to examine regional patterns in the responses of benthic macroinvertebrates and algae to urbanization across 9 metropolitan areas of the conterminous USA. Linear regressions established that responses (intercepts and slopes) to urbanization of invertebrates and algae varied among metropolitan areas. Multilevel hierarchical regression models were able to explain these differences on the basis of region-scale predictors. Regional differences in the type of land cover (agriculture or forest) being converted to urban and climatic factors (precipitation and air temperature) accounted for the differences in the response of macroinvertebrates to urbanization based on ordination scores, total richness, Ephemeroptera, Plecoptera, Trichoptera richness, and average tolerance. Regional differences in climate and antecedent agriculture also accounted for differences in the responses of salt-tolerant diatoms, but differences in the responses of other diatom metrics (% eutraphenic, % sensitive, and % silt tolerant) were best explained by regional differences in soils (mean % clay soils). The effects of urbanization were most readily detected in regions where forest lands were being converted to urban land because agricultural development significantly degraded assemblages before urbanization and made detection of urban effects difficult. The effects of climatic factors (temperature, precipitation) on background conditions (biogeographic differences) and rates of response to urbanization were most apparent after accounting for the effects of agricultural development. The effects of climate and land cover on responses to urbanization provide strong evidence that monitoring, mitigation, and restoration efforts must be tailored for specific regions and that attainment goals (background conditions) may not be possible in regions with high levels of prior disturbance (e.g., agricultural development). ?? 2011 by The North American

  13. A holistic conceptual framework model to describe medication adherence in and guide interventions in diabetes mellitus.

    Science.gov (United States)

    Jaam, Myriam; Awaisu, Ahmed; Mohamed Ibrahim, Mohamed Izham; Kheir, Nadir

    2018-04-01

    Nonadherence to medications in patients with diabetes, which results in poor treatment outcomes and increased healthcare costs, is commonly reported globally. Factors associated with medication adherence have also been widely studied. However, a clear and comprehensive, disease-specific conceptual framework model that captures all possible factors has not been established. This study aimed to develop a conceptual framework that addresses the complex network of barriers to medication adherence in patients with diabetes. Fourteen databases and grey literature sources were systematically searched for systematic reviews reporting barriers to medication adherence in patients with diabetes. A thematic approach was used to categorize all identified barriers from the reviews and to create a matrix representing the complex network and relations of the different barriers. Eighteen systematic reviews were identified and used for the development of the conceptual framework. Overall, six major themes emerged: patient-, medication-, disease-, provider-, system-, and societal-related factors. Each of these themes was further classified into different sub-categories. It was noted that most interactions were identified to be within the patient-related factors, which not only interact with other themes but also within the same theme. Patient's demographics as well as cultural beliefs were the most notable factors in terms of interactions with other categories and themes. The intricate network and interaction of factors identified between different themes and within individual themes indicate the complexity of the problem of adherence. This framework will potentially enhance the understanding of the complex relation between different barriers for medication adherence in diabetes and will facilitate design of more effective interventions. Future interventions for enhancing medication adherence should look at the overall factors and target multiple themes of barriers to improve patient

  14. Global qualitative analysis of a quartic ecological model

    NARCIS (Netherlands)

    Broer, Hendrik; Gaiko, Valery A.

    2010-01-01

    in this paper we complete the global qualitative analysis of a quartic ecological model. In particular, studying global bifurcations of singular points and limit cycles, we prove that the corresponding dynamical system has at most two limit cycles. (C) 2009 Elsevier Ltd. All rights reserved.

  15. Semimechanistic model describing gastric emptying and glucose absorption in healthy subjects and patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Alskär, Oskar; Bagger, Jonatan I; Røge, Rikke M.

    2016-01-01

    The integrated glucose-insulin (IGI) model is a previously published semimechanistic model that describes plasma glucose and insulin concentrations after glucose challenges. The aim of this work was to use knowledge of physiology to improve the IGI model's description of glucose absorption and ga...... model provides a better description and improves the understanding of dynamic glucose tests involving oral glucose....... and gastric emptying after tests with varying glucose doses. The developed model's performance was compared to empirical models. To develop our model, data from oral and intravenous glucose challenges in patients with type 2 diabetes and healthy control subjects were used together with present knowledge...... glucose absorption was superior to linear absorption regardless of the gastric emptying model applied. The semiphysiological model developed performed better than previously published empirical models and allows better understanding of the mechanisms underlying glucose absorption. In conclusion, our new...

  16. A standardised graphic method for describing data privacy frameworks in primary care research using a flexible zone model.

    NARCIS (Netherlands)

    Kuchinke, W.; Ohmann, C.; Verheij, R.A.; Veen, E.B. van; Arvanitis, T.N.; Taweel, A.; Delaney, B.C.

    2014-01-01

    Purpose: To develop a model describing core concepts and principles of data flow, data privacy and confidentiality, in a simple and flexible way, using concise process descriptions and a diagrammatic notation applied to research workflow processes. The model should help to generate robust data

  17. Automated Techniques for the Qualitative Analysis of Ecological Models: Continuous Models

    Directory of Open Access Journals (Sweden)

    Lynn van Coller

    1997-06-01

    Full Text Available The mathematics required for a detailed analysis of the behavior of a model can be formidable. In this paper, I demonstrate how various computer packages can aid qualitative analyses by implementing techniques from dynamical systems theory. Because computer software is used to obtain the results, the techniques can be used by nonmathematicians as well as mathematicians. In-depth analyses of complicated models that were previously very difficult to study can now be done. Because the paper is intended as an introduction to applying the techniques to ecological models, I have included an appendix describing some of the ideas and terminology. A second appendix shows how the techniques can be applied to a fairly simple predator-prey model and establishes the reliability of the computer software. The main body of the paper discusses a ratio-dependent model. The new techniques highlight some limitations of isocline analyses in this three-dimensional setting and show that the model is structurally unstable. Another appendix describes a larger model of a sheep-pasture-hyrax-lynx system. Dynamical systems techniques are compared with a traditional sensitivity analysis and are found to give more information. As a result, an incomplete relationship in the model is highlighted. I also discuss the resilience of these models to both parameter and population perturbations.

  18. Performance of flash profile and napping with and without training for describing small sensory differences in a model wine

    DEFF Research Database (Denmark)

    Liu, Jing; Grønbeck, Marlene Schou; Di Monaco, Rosella

    2016-01-01

    . In this study different variations of two rapid sensory methods, one based on holistic assessment – Napping, and one based on attribute evaluation – Flash Profile, were tested for the evaluation of the flavour in wine. Model wines were developed with control over the sensory differences in terms of sensory...... to arrange samples on the sheet) or the product (familiarisation with the sensory properties of the wines) improved the outcome compared to the classical Napping protocol. The classical Flash Profile protocol and its modified version including a Napping with subsequent attributes generation as the word...... generation step and limiting the number of attributes for ranking gave a similar sample space. The Napping method could best highlight qualitative sample differences, whereas the Flash Profile provided a more precise product mapping on quantitative differences between model wines....

  19. A comparison of macroscopic models describing the collective response of sedimenting rod-like particles in shear flows

    KAUST Repository

    Helzel, Christiane; Tzavaras, Athanasios

    2016-01-01

    We consider a kinetic model, which describes the sedimentation of rod-like particles in dilute suspensions under the influence of gravity, presented in Helzel and Tzavaras (submitted for publication). Here we restrict our considerations to shear flow and consider a simplified situation, where the particle orientation is restricted to the plane spanned by the direction of shear and the direction of gravity. For this simplified kinetic model we carry out a linear stability analysis and we derive two different nonlinear macroscopic models which describe the formation of clusters of higher particle density. One of these macroscopic models is based on a diffusive scaling, the other one is based on a so-called quasi-dynamic approximation. Numerical computations, which compare the predictions of the macroscopic models with the kinetic model, complete our presentation.

  20. A comparison of macroscopic models describing the collective response of sedimenting rod-like particles in shear flows

    KAUST Repository

    Helzel, Christiane

    2016-07-22

    We consider a kinetic model, which describes the sedimentation of rod-like particles in dilute suspensions under the influence of gravity, presented in Helzel and Tzavaras (submitted for publication). Here we restrict our considerations to shear flow and consider a simplified situation, where the particle orientation is restricted to the plane spanned by the direction of shear and the direction of gravity. For this simplified kinetic model we carry out a linear stability analysis and we derive two different nonlinear macroscopic models which describe the formation of clusters of higher particle density. One of these macroscopic models is based on a diffusive scaling, the other one is based on a so-called quasi-dynamic approximation. Numerical computations, which compare the predictions of the macroscopic models with the kinetic model, complete our presentation.

  1. Downscaling SSPs in the GBM Delta - Integrating Science, Modelling and Stakeholders Through Qualitative and Quantitative Scenarios

    Science.gov (United States)

    Allan, Andrew; Barbour, Emily; Salehin, Mashfiqus; Munsur Rahman, Md.; Hutton, Craig; Lazar, Attila

    2016-04-01

    A downscaled scenario development process was adopted in the context of a project seeking to understand relationships between ecosystem services and human well-being in the Ganges-Brahmaputra delta. The aim was to link the concerns and priorities of relevant stakeholders with the integrated biophysical and poverty models used in the project. A 2-stage process was used to facilitate the connection between stakeholders concerns and available modelling capacity: the first to qualitatively describe what the future might look like in 2050; the second to translate these qualitative descriptions into the quantitative form required by the numerical models. An extended, modified SSP approach was adopted, with stakeholders downscaling issues identified through interviews as being priorities for the southwest of Bangladesh. Detailed qualitative futures were produced, before modellable elements were quantified in conjunction with an expert stakeholder cadre. Stakeholder input, using the methods adopted here, allows the top-down focus of the RCPs to be aligned with the bottom-up approach needed to make the SSPs appropriate at the more local scale, and also facilitates the translation of qualitative narrative scenarios into a quantitative form that lends itself to incorporation of biophysical and socio-economic indicators. The presentation will describe the downscaling process in detail, and conclude with findings regarding the importance of stakeholder involvement (and logistical considerations), balancing model capacity with expectations and recommendations on SSP refinement at local levels.

  2. Downscaling SSPs in Bangladesh - Integrating Science, Modelling and Stakeholders Through Qualitative and Quantitative Scenarios

    Science.gov (United States)

    Allan, A.; Barbour, E.; Salehin, M.; Hutton, C.; Lázár, A. N.; Nicholls, R. J.; Rahman, M. M.

    2015-12-01

    A downscaled scenario development process was adopted in the context of a project seeking to understand relationships between ecosystem services and human well-being in the Ganges-Brahmaputra delta. The aim was to link the concerns and priorities of relevant stakeholders with the integrated biophysical and poverty models used in the project. A 2-stage process was used to facilitate the connection between stakeholders concerns and available modelling capacity: the first to qualitatively describe what the future might look like in 2050; the second to translate these qualitative descriptions into the quantitative form required by the numerical models. An extended, modified SSP approach was adopted, with stakeholders downscaling issues identified through interviews as being priorities for the southwest of Bangladesh. Detailed qualitative futures were produced, before modellable elements were quantified in conjunction with an expert stakeholder cadre. Stakeholder input, using the methods adopted here, allows the top-down focus of the RCPs to be aligned with the bottom-up approach needed to make the SSPs appropriate at the more local scale, and also facilitates the translation of qualitative narrative scenarios into a quantitative form that lends itself to incorporation of biophysical and socio-economic indicators. The presentation will describe the downscaling process in detail, and conclude with findings regarding the importance of stakeholder involvement (and logistical considerations), balancing model capacity with expectations and recommendations on SSP refinement at local levels.

  3. A Comparison of Models Describing Heat Transfer in the Primary Cooling Zone of a Continuous Casting Machine

    Directory of Open Access Journals (Sweden)

    Miłkowska-Piszczek K.

    2015-04-01

    Full Text Available This paper presents the findings of research conducted concerning the determination of thermal boundary conditions for the steel continuous casting process within the primary cooling zone. A cast slab - with dimensions of 1100 mm×220 mm - was analysed, and models described in references were compared with the authors’ model. The presented models were verified on the basis of an industrial database. The research problem was solved with the finite element method using the ProCAST software package.

  4. 'This little piranha': a qualitative analysis of the language used by health professionals and mothers to describe infant behaviour during breastfeeding.

    Science.gov (United States)

    Burns, Elaine; Fenwick, Jenny; Sheehan, Athena; Schmied, Virginia

    2016-01-01

    Exclusive breastfeeding for the first 6 months of life offers the recommended best start in the life for a newborn baby. Yet, in Australia only a small number of babies receive breast milk exclusively for the first 6 months. Reasons for the introduction of formula milk are multi-factorial including access to appropriate support and the woman's experience of breastfeeding. The language and practices of health professionals can impact upon how a woman feels about breastfeeding and her breastfeeding body. One aspect of breastfeeding support that has had scarce attention in the literature is the language used by health professionals to describe the behaviour of the breastfeeding infant during the early establishment phase of breastfeeding. This paper reveals some of the ways in which midwives, lactation consultants and breastfeeding women describe the newborn baby during the first week after birth. The study was conducted at two maternity units in New South Wales. Interactions between midwives and breastfeeding women were observed and audio recorded on the post-natal ward and in women's homes, in the first week after birth. The transcribed data were analysed using discourse analysis searching for recurring words, themes and metaphors used in descriptions of the breastfeeding baby. Repeated negative references to infant personality and unfavourable interpretations of infant behaviour influenced how women perceived their infant. The findings revealed that positive language and interpretations of infant breastfeeding behaviour emerged from more relationship-based communication. © 2015 John Wiley & Sons Ltd.

  5. From qualitative reasoning models to Bayesian-based learner modeling

    NARCIS (Netherlands)

    Milošević, U.; Bredeweg, B.; de Kleer, J.; Forbus, K.D.

    2010-01-01

    Assessing the knowledge of a student is a fundamental part of intelligent learning environments. We present a Bayesian network based approach to dealing with uncertainty when estimating a learner’s state of knowledge in the context of Qualitative Reasoning (QR). A proposal for a global architecture

  6. Adolescents just do not know what they want: a qualitative study to describe obese adolescents' experiences of text messaging to support behavior change maintenance post intervention.

    Science.gov (United States)

    Smith, Kyla L; Kerr, Deborah A; Fenner, Ashley A; Straker, Leon M

    2014-04-08

    Adolescents are considered a hard to reach group and novel approaches are needed to encourage good health. Text messaging interventions have been reported as acceptable to adolescents but there is little evidence regarding the use of text messages with overweight and obese adolescents to support engagement or behavior change after the conclusion of a healthy lifestyle program. The intent of this study was to explore the opinions of overweight adolescents and their parents regarding the use of text messages as a support during the maintenance period following an intervention. This paper reports on the findings from focus groups conducted with adolescents (n=12) and parents (n=13) who had completed an eight-week intensive intervention known as Curtin University's Activity, Food and Attitudes Program (CAFAP). Focus groups were conducted three months post intensive intervention. Participants were asked about their experiences of the prior three-month maintenance phase during which adolescents had received tri-weekly text messages based on the self-determination theory and goal-setting theory. Participants were asked about the style and content of text messages used as well as how they used the text messages. Data were analyzed using content and thematic analyses. Two clear themes emerged from the focus groups relating to (1) what adolescents liked or thought they wanted in a text message to support behavior change, and (2) how they experienced or responded to text messages. Within the "like/want" theme, there were five sub-themes relating to the overall tone of the text, frequency, timing, reference to long-term goals, and inclusion of practical tips. Within the "response to text" theme, there were four sub-themes describing a lack of motivation, barriers to change, feelings of shame, and perceived unfavorable comparison with other adolescents. What adolescents said they wanted in text messages often conflicted with their actual experiences. Parent reports provided a

  7. Adolescents Just Do Not Know What They Want: A Qualitative Study to Describe Obese Adolescents’ Experiences of Text Messaging to Support Behavior Change Maintenance Post Intervention

    Science.gov (United States)

    Kerr, Deborah A; Fenner, Ashley A; Straker, Leon M

    2014-01-01

    Background Adolescents are considered a hard to reach group and novel approaches are needed to encourage good health. Text messaging interventions have been reported as acceptable to adolescents but there is little evidence regarding the use of text messages with overweight and obese adolescents to support engagement or behavior change after the conclusion of a healthy lifestyle program. Objective The intent of this study was to explore the opinions of overweight adolescents and their parents regarding the use of text messages as a support during the maintenance period following an intervention. Methods This paper reports on the findings from focus groups conducted with adolescents (n=12) and parents (n=13) who had completed an eight-week intensive intervention known as Curtin University’s Activity, Food and Attitudes Program (CAFAP). Focus groups were conducted three months post intensive intervention. Participants were asked about their experiences of the prior three-month maintenance phase during which adolescents had received tri-weekly text messages based on the self-determination theory and goal-setting theory. Participants were asked about the style and content of text messages used as well as how they used the text messages. Data were analyzed using content and thematic analyses. Results Two clear themes emerged from the focus groups relating to (1) what adolescents liked or thought they wanted in a text message to support behavior change, and (2) how they experienced or responded to text messages. Within the “like/want” theme, there were five sub-themes relating to the overall tone of the text, frequency, timing, reference to long-term goals, and inclusion of practical tips. Within the “response to text” theme, there were four sub-themes describing a lack of motivation, barriers to change, feelings of shame, and perceived unfavorable comparison with other adolescents. What adolescents said they wanted in text messages often conflicted with their

  8. Validation of a Simulation Model Describing the Glucose-Insulin-Glucagon Pharmacodynamics in Patients with Type 1 Diabetes

    DEFF Research Database (Denmark)

    Wendt, Sabrina Lyngbye; Ranjan, Ajenthen; Møller, Jan Kloppenborg

    Currently, no consensus exists on a model describing endogenous glucose production (EGP) as a function of glucagon concentrations. Reliable simulations to determine the glucagon dose preventing or treating hypoglycemia or to tune a dual-hormone artificial pancreas control algorithm need a validat...

  9. Biological Effectiveness and Application of Heavy Ions in Radiation Therapy Described by a Physical and Biological Model

    DEFF Research Database (Denmark)

    Olsen, Kjeld J.; Hansen, Johnny W.

    is inadequately described by an RBE-factor, whereas the complete formulation of the probability of survival must be used, as survival depends on both radiation quality and dose. The theoretical model of track structure can be used in dose-effect calculations for neutron-, high-LET, and low-LET radiation applied...... simultaneously in therapy....

  10. A standardised graphic method for describing data privacy frameworks in primary care research using a flexible zone model.

    Science.gov (United States)

    Kuchinke, Wolfgang; Ohmann, Christian; Verheij, Robert A; van Veen, Evert-Ben; Arvanitis, Theodoros N; Taweel, Adel; Delaney, Brendan C

    2014-12-01

    To develop a model describing core concepts and principles of data flow, data privacy and confidentiality, in a simple and flexible way, using concise process descriptions and a diagrammatic notation applied to research workflow processes. The model should help to generate robust data privacy frameworks for research done with patient data. Based on an exploration of EU legal requirements for data protection and privacy, data access policies, and existing privacy frameworks of research projects, basic concepts and common processes were extracted, described and incorporated into a model with a formal graphical representation and a standardised notation. The Unified Modelling Language (UML) notation was enriched by workflow and own symbols to enable the representation of extended data flow requirements, data privacy and data security requirements, privacy enhancing techniques (PET) and to allow privacy threat analysis for research scenarios. Our model is built upon the concept of three privacy zones (Care Zone, Non-care Zone and Research Zone) containing databases, data transformation operators, such as data linkers and privacy filters. Using these model components, a risk gradient for moving data from a zone of high risk for patient identification to a zone of low risk can be described. The model was applied to the analysis of data flows in several general clinical research use cases and two research scenarios from the TRANSFoRm project (e.g., finding patients for clinical research and linkage of databases). The model was validated by representing research done with the NIVEL Primary Care Database in the Netherlands. The model allows analysis of data privacy and confidentiality issues for research with patient data in a structured way and provides a framework to specify a privacy compliant data flow, to communicate privacy requirements and to identify weak points for an adequate implementation of data privacy. Copyright © 2014 Elsevier Ireland Ltd. All rights

  11. Evidence in Support of the Independent Channel Model Describing the Sensorimotor Control of Human Stance Using a Humanoid Robot.

    Science.gov (United States)

    Pasma, Jantsje H; Assländer, Lorenz; van Kordelaar, Joost; de Kam, Digna; Mergner, Thomas; Schouten, Alfred C

    2018-01-01

    The Independent Channel (IC) model is a commonly used linear balance control model in the frequency domain to analyze human balance control using system identification and parameter estimation. The IC model is a rudimentary and noise-free description of balance behavior in the frequency domain, where a stable model representation is not guaranteed. In this study, we conducted firstly time-domain simulations with added noise, and secondly robot experiments by implementing the IC model in a real-world robot (PostuRob II) to test the validity and stability of the model in the time domain and for real world situations. Balance behavior of seven healthy participants was measured during upright stance by applying pseudorandom continuous support surface rotations. System identification and parameter estimation were used to describe the balance behavior with the IC model in the frequency domain. The IC model with the estimated parameters from human experiments was implemented in Simulink for computer simulations including noise in the time domain and robot experiments using the humanoid robot PostuRob II. Again, system identification and parameter estimation were used to describe the simulated balance behavior. Time series, Frequency Response Functions, and estimated parameters from human experiments, computer simulations, and robot experiments were compared with each other. The computer simulations showed similar balance behavior and estimated control parameters compared to the human experiments, in the time and frequency domain. Also, the IC model was able to control the humanoid robot by keeping it upright, but showed small differences compared to the human experiments in the time and frequency domain, especially at high frequencies. We conclude that the IC model, a descriptive model in the frequency domain, can imitate human balance behavior also in the time domain, both in computer simulations with added noise and real world situations with a humanoid robot. This

  12. Evidence in Support of the Independent Channel Model Describing the Sensorimotor Control of Human Stance Using a Humanoid Robot

    Directory of Open Access Journals (Sweden)

    Jantsje H. Pasma

    2018-03-01

    Full Text Available The Independent Channel (IC model is a commonly used linear balance control model in the frequency domain to analyze human balance control using system identification and parameter estimation. The IC model is a rudimentary and noise-free description of balance behavior in the frequency domain, where a stable model representation is not guaranteed. In this study, we conducted firstly time-domain simulations with added noise, and secondly robot experiments by implementing the IC model in a real-world robot (PostuRob II to test the validity and stability of the model in the time domain and for real world situations. Balance behavior of seven healthy participants was measured during upright stance by applying pseudorandom continuous support surface rotations. System identification and parameter estimation were used to describe the balance behavior with the IC model in the frequency domain. The IC model with the estimated parameters from human experiments was implemented in Simulink for computer simulations including noise in the time domain and robot experiments using the humanoid robot PostuRob II. Again, system identification and parameter estimation were used to describe the simulated balance behavior. Time series, Frequency Response Functions, and estimated parameters from human experiments, computer simulations, and robot experiments were compared with each other. The computer simulations showed similar balance behavior and estimated control parameters compared to the human experiments, in the time and frequency domain. Also, the IC model was able to control the humanoid robot by keeping it upright, but showed small differences compared to the human experiments in the time and frequency domain, especially at high frequencies. We conclude that the IC model, a descriptive model in the frequency domain, can imitate human balance behavior also in the time domain, both in computer simulations with added noise and real world situations with a

  13. Is coronene better described by Clar's aromatic π-sextet model or by the AdNDP representation?

    Science.gov (United States)

    Kumar, Anand; Duran, Miquel; Solà, Miquel

    2017-07-05

    The bonding patterns in coronene are complicated and controversial as denoted by the lack of consensus of how its electronic structure should be described. Among the different proposed descriptions, the two most representative are those generated by Clar's aromatic π-sextet and adaptative natural density partitioning (AdNDP) models. Quantum-chemical calculations at the density functional theory level are performed to evaluate the model that gives a better representation of coronene. To this end, we analyse the molecular structure of coronene, we estimate the aromaticity of its inner and outer rings using various local aromaticity descriptors, and we assess its chemical reactivity from the study of the Diels-Alder reaction with cyclopentadiene. Results obtained are compared with those computed for naphthalene and phenanthrene. Our conclusion is that Clar's π-sextet model provides the representation of coronene that better describes the physicochemical behavior of this molecule. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  14. KANDY - a numerical model to describe phenomena, which - in a heated and voided fuel element of an LMFBR - may occur

    International Nuclear Information System (INIS)

    Thurnay, K.

    1984-02-01

    Kandy is a model developed to describe the essential destructionphenomena of the fuel elements of an LMFBR. The fuel element is assumed to be a voided one, in which the heat generation is still going on. The main process to be modeled is the melting/bursting/evaporating of parts of the fuel pins and the subsequent dislocation of these materials in the coolant channel. The work presented summarizes the assumptions constituting the model, develops the corresponding equations of motion and describes the procedure, turning these into a system of difference-equations ready for coding. As a final part results of a testcase calculation with the Kandy-code are presentend and interpreted. (orig.) [de

  15. A new model describing the curves for repair of both DNA double-strand breaks and chromosome damage

    International Nuclear Information System (INIS)

    Foray, N.; Badie, C.; Alsbeih, G.; Malaise, E.P.; Fertil, B.

    1996-01-01

    A review of reports dealing with fittings of the data for repair of DNA double-strand breaks (DSBs) and excess chromosome fragments (ECFs) shows that several models are used to fit the repair curves. Since DSBs and ECFs are correleated, it is worth developing a model describing both phenomena. The curve-fitting models used most extensively, the two repair half-times model for DSBs and the monoexponential plus residual model for ECFs, appear to be too inflexible to describe the repair curves for both DSBs and ECFs. We have therefore developed a new concept based on a variable repair half-time. According to this concept, the repair curve is continuously bending and dependent on time and probably reflects a continuous spectrum of damage repairability. The fits of the curves for DSB repair to the variable repair half-time and the variable repair half-time plus residual models were compared to those obtained with the two half-times plus residual and two half-times models. Similarly, the fits of the curves for ECF repair to the variable repair half-time and variable half-time plus residual models were compared to that obtained with the monoexponential plus residual model. The quality of fit and the dependence of adjustable parameters on the portion of the curve fitted were used as comparison criteria. We found that: (a) It is useful to postulate the existence of a residual term for unrepairable lesions, regardless of the model adopted. (b) With the two cell lines tested (a normal and a hypersensitive one), data for both DSBs and ECTs are best fitted to the variable repair half-time plus residual model, whatever the repair time range. 47 refs., 3 figs., 3 tabs

  16. DaMoScope and its internet graphics for the visual control of adjusting mathematical models describing experimental data

    International Nuclear Information System (INIS)

    Belousov, V. I.; Ezhela, V. V.; Kuyanov, Yu. V.; Tkachenko, N. P.

    2015-01-01

    The experience of using the dynamic atlas of the experimental data and mathematical models of their description in the problems of adjusting parametric models of observable values depending on kinematic variables is presented. The functional possibilities of an image of a large number of experimental data and the models describing them are shown by examples of data and models of observable values determined by the amplitudes of elastic scattering of hadrons. The Internet implementation of an interactive tool DaMoScope and its interface with the experimental data and codes of adjusted parametric models with the parameters of the best description of data are schematically shown. The DaMoScope codes are freely available

  17. DaMoScope and its internet graphics for the visual control of adjusting mathematical models describing experimental data

    Science.gov (United States)

    Belousov, V. I.; Ezhela, V. V.; Kuyanov, Yu. V.; Tkachenko, N. P.

    2015-12-01

    The experience of using the dynamic atlas of the experimental data and mathematical models of their description in the problems of adjusting parametric models of observable values depending on kinematic variables is presented. The functional possibilities of an image of a large number of experimental data and the models describing them are shown by examples of data and models of observable values determined by the amplitudes of elastic scattering of hadrons. The Internet implementation of an interactive tool DaMoScope and its interface with the experimental data and codes of adjusted parametric models with the parameters of the best description of data are schematically shown. The DaMoScope codes are freely available.

  18. DaMoScope and its internet graphics for the visual control of adjusting mathematical models describing experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Belousov, V. I.; Ezhela, V. V.; Kuyanov, Yu. V., E-mail: Yu.Kuyanov@gmail.com; Tkachenko, N. P. [Institute for High Energy Physics, National Research Center Kurchatov Institute, COMPAS Group (Russian Federation)

    2015-12-15

    The experience of using the dynamic atlas of the experimental data and mathematical models of their description in the problems of adjusting parametric models of observable values depending on kinematic variables is presented. The functional possibilities of an image of a large number of experimental data and the models describing them are shown by examples of data and models of observable values determined by the amplitudes of elastic scattering of hadrons. The Internet implementation of an interactive tool DaMoScope and its interface with the experimental data and codes of adjusted parametric models with the parameters of the best description of data are schematically shown. The DaMoScope codes are freely available.

  19. A New Model for Describing the Rheological Behavior of Heavy and Extra Heavy Crude Oils in the Presence of Nanoparticles

    Directory of Open Access Journals (Sweden)

    Esteban A. Taborda

    2017-12-01

    Full Text Available The present work proposes for the first time a mathematical model for describing the rheological behavior of heavy and extra-heavy crude oils in the presence of nanoparticles. This model results from the combination of two existing mathematical models. The first one applies to the rheology of pseudoplastic substances, i.e., the Herschel-Bulkley model. The second one was previously developed by our research group to model the rheology of suspensions, namely the modified Pal and Rhodes model. The proposed model is applied to heavy and extra heavy crude oils in the presence of nanoparticles, considering the effects of nanoparticles concentration and surface chemical nature, temperature, and crude oil type. All the experimental data evaluated exhibited compelling goodness of fitting, and the physical parameters in the model follow correlate well with variations in viscosity. The new model is dependent of share rate and opens new possibilities for phenomenologically understanding viscosity reduction in heavy crude by adding solid nanoparticles and favoring the scale-up in enhanced oil recovery (EOR and/or improved oil recovery (IOR process.

  20. Evaluation and Validation of a TCAT Model to Describe Non-Dilute Flow and Species Transport in Porous Media

    Science.gov (United States)

    Weigand, T. M.; Harrison, E.; Miller, C. T.

    2017-12-01

    A thermodynamically constrained averaging theory (TCAT) model has been developed to simulate non-dilute flow and species transport in porous media. This model has the advantages of a firm connection between the microscale, or pore scale, and the macroscale; a thermodynamically consistent basis; the explicit inclusion of dissipative terms that arise from spatial gradients in pressure and chemical activity; and the ability to describe both high and low concentration displacement. The TCAT model has previously been shown to provide excellent agreement for a set of laboratory data and outperformed existing macroscale models that have been used for non-dilute flow and transport. The examined experimental dataset consisted of stable brine displacements for a large range of fluid properties. This dataset however only examined one type of porous media and had a fixed flow rate for all experiments. In this work, the TCAT model is applied to a dataset that consists of two different porous media types, constant head and flow rate conditions, varying resident fluid concentrations, and internal probes that measured the pressure and salt mass fraction. Parameter estimation is performed on a subset of the experimental data for the TCAT model as well as other existing non-dilute flow and transport models. The optimized parameters are then used for forward simulations and the accuracy of the models is compared.

  1. Users' guide to system dynamics model describing Coho salmon survival in Olema Creek, Point Reyes National Seashore, Marin County, California

    Science.gov (United States)

    Woodward, Andrea; Torregrosa, Alicia; Madej, Mary Ann; Reichmuth, Michael; Fong, Darren

    2014-01-01

    The system dynamics model described in this report is the result of a collaboration between U.S. Geological Survey (USGS) scientists and National Park Service (NPS) San Francisco Bay Area Network (SFAN) staff, whose goal was to develop a methodology to integrate inventory and monitoring data to better understand ecosystem dynamics and trends using salmon in Olema Creek, Marin County, California, as an example case. The SFAN began monitoring multiple life stages of coho salmon (Oncorhynchus kisutch) in Olema Creek during 2003 (Carlisle and others, 2013), building on previous monitoring of spawning fish and redds. They initiated water-quality and habitat monitoring, and had access to flow and weather data from other sources. This system dynamics model of the freshwater portion of the coho salmon life cycle in Olema Creek integrated 8 years of existing monitoring data, literature values, and expert opinion to investigate potential factors limiting survival and production, identify data gaps, and improve monitoring and restoration prescriptions. A system dynamics model is particularly effective when (1) data are insufficient in time series length and/or measured parameters for a statistical or mechanistic model, and (2) the model must be easily accessible by users who are not modelers. These characteristics helped us meet the following overarching goals for this model: Summarize and synthesize NPS monitoring data with data and information from other sources to describe factors and processes affecting freshwater survival of coho salmon in Olema Creek. Provide a model that can be easily manipulated to experiment with alternative values of model parameters and novel scenarios of environmental drivers. Although the model describes the ecological dynamics of Olema Creek, these dynamics are structurally similar to numerous other coastal streams along the California coast that also contain anadromous fish populations. The model developed for Olema can be used, at least as a

  2. An analytical mechanical model to describe the response of NiTi rotary endodontic files in a curved root canal

    International Nuclear Information System (INIS)

    Leroy, Agnès Marie Françoise; Bahia, Maria Guiomar de Azevedo; Ehrlacher, Alain; Buono, Vicente Tadeu Lopes

    2012-01-01

    Aim: To build a mathematical model describing the mechanical behavior of NiTi rotary files while they are rotating in a root canal. Methodology: The file was seen as a beam undergoing large transformations. The instrument was assumed to be rotating steadily in the root canal, and the geometry of the canal was considered as a known parameter of the problem. The formulae of large transformations mechanics then allowed the calculation of the Green–Lagrange strain field in the file. The non-linear mechanical behavior of NiTi was modeled as a continuous piecewise linear function, assuming that the material did not reach plastic deformation. Criteria locating the changes of behavior of NiTi were established and the tension field in the file, and the external efforts applied on it were calculated. The unknown variable of torsion was deduced from the equilibrium equation system using a Coulomb contact law which solved the problem on a cycle of rotation. Results: In order to verify that the model described well reality, three-point bending experiments were managed on superelastic NiTi wires, whose results were compared to the theoretical ones. It appeared that the model gave a good mentoring of the empirical results in the range of bending angles that interested us. Conclusions: Knowing the geometry of the root canal, one is now able to write the equations of the strain and stress fields in the endodontic instrument, and to quantify the impact of each macroscopic parameter of the problem on its response. This should be useful to predict failure of the files under rotating bending fatigue, and to optimize the geometry of the files. - Highlights: ► A mechanical model of the behavior of a NiTi endodontic instrument was developed. ► The model was validated with results of three-point bending tests on NiTi wires. ► The model is appropriate for the optimization of instruments' geometry.

  3. Evaluation of a cross contamination model describing transfer of Salmonella spp. and Listeria monocytogenes during grinding of pork and beef.

    Science.gov (United States)

    Møller, C O A; Sant'Ana, A S; Hansen, S K H; Nauta, M J; Silva, L P; Alvarenga, V O; Maffei, D; Silva, F F P; Lopes, J T; Franco, B D G M; Aabo, S; Hansen, T B

    2016-06-02

    In a previous study, a model was developed to describe the transfer and survival of Salmonella during grinding of pork (Møller, C.O.A., Nauta, M.J., Christensen, B.B., Dalgaard, P., Hansen, T.B., 2012. Modelling transfer of Salmonella typhimurium DT104 during simulation of grinding of pork. Journal of Applied Microbiology 112 (1), 90-98). The robustness of this model is now evaluated by studying its performance for predicting the transfer and survival of Salmonella spp. and Listeria monocytogenes during grinding of different types of meat (pork and beef), using two different grinders, different sizes and different numbers of pieces of meats to be ground. A total of 19 grinding trials were collected. Acceptable Simulation Zone (ASZ), visual inspection of the data, Quantitative Microbiological Risk Assessment (QMRA), as well as the Total Transfer Potential (TTP) were used as approaches to evaluate model performance and to access the quality of the cross contamination model predictions. Using the ASZ approach and considering that 70% of the observed counts have to be inside a defined acceptable zone of ±0.5 log10CFU per portion, it was found that the cross contamination parameters suggested by Møller et al. (2012) were not able to describe all 19 trials. However, for each of the collected grinding trials, the transfer event was well described when fitted to the model structure proposed by Møller et al. (2012). Parameter estimates obtained by fitting observed trials performed at different conditions, such as size and number of pieces of meat to be ground, may not be applied to describe cross contamination of unlike processing. Nevertheless, the risk estimates, as well as the TTP, revealed that the risk of disease may be reduced when the grinding of meat is performed in a grinder made of stainless steel (for all surfaces in contact with the meat), using a well-sharpened knife and holding at room temperatures lower than 4°C. Copyright © 2016 Elsevier B.V. All

  4. The Polyakov, Nambu and Jona-Lasinio model and its applications to describe the sub-nuclear particles

    International Nuclear Information System (INIS)

    Blanquier, E.

    2013-01-01

    To study the high energy nuclear physics and the associated phenomenon, as the quark-gluon plasma / hadronic matter phase transition, the Nambu and Jona-Lasinio model (NJL) appears as an interesting alternative to the Quantum Chromodynamics, not solvable at the considered energies. Indeed, the NJL model allows the description of quarks physics, at finite temperatures and densities. Furthermore, in order to try to correct a limitation of the NJL model, i.e. the absence of confinement, it was proposed a coupling of the quarks/antiquarks to a Polyakov loop, forming the PNJL model. The objective of this thesis is to see the possibilities offered by the NJL and PNJL models, to describe relevant sub-nuclear particles (quarks, mesons, diquarks and baryons), to study their interactions, and to proceed to a dynamical study involving these particles. After a recall of the useful tools, we modeled the u, d, s effective quarks and the mesons. Then, we described the baryons as quarks-diquarks bound states. A part of the work concerned the calculations of the cross-sections associated to the possible reactions implying these particles. Then, we incorporated these results in a computer code, in order to study the cooling of a quarks/antiquarks plasma and its hadronization. In this study, each particle evolves in a system in which the temperature and the densities are local parameters. We have two types of interactions: one due to the collisions, and the other is a remote interaction, notably between quarks. Finally, we studied the properties of our approach: qualities, limitations, and possible evolutions. (author)

  5. Evaluation of a cross contamination model describing transfer of salmonella spp. and listeria monocytogenes during grinding of pork and beef

    DEFF Research Database (Denmark)

    Møller, Cleide Oliveira de Almeida; Hansen, Tina Beck; Aabo, Søren

    2015-01-01

    Introduction: The cross contamination model (Møller et al. 2012) was evaluated to investigate its capability of describing transfer of Salmonella spp. and Listeria monocytogenes during grinding of pork and beef of varying sizes (50 – 324 g) and numbers of pieces to be ground (10 – 100), in two...... processing. QMRA risk estimates and TTP both revealed that risk attribution from grinding was mainly influenced by sharpness of grinder knife > specific grinder > grinding temperature whereas the specific pathogen was of minor importance....

  6. Biological effectiveness and application of heavy ions in radiation therapy described by a physical and biological model

    International Nuclear Information System (INIS)

    Olsen, K.J.; Hansen, J.W.

    1982-12-01

    A description is given of the physical basis for applying track structure theory in the determination of the effectiveness of heavy-ion irradiation of single- and multi-hit target systems. It will be shown that for applying the theory to biological systems the effectiveness of heavy-ion irradiation is inadequately described by an RBE-factor, whereas the complete formulation of the probability of survival must be used, as survival depends on both radiation quality and dose. The theoretical model of track structure can be used in dose-effect calculations for neutron-, high-LET, and low-LET radiation applied simultaneously in therapy. (author)

  7. Applying a physical continuum model to describe the broadband X-ray spectra of accreting pulsars at high luminosity

    Science.gov (United States)

    Pottschmidt, Katja; Hemphill, Paul B.; Wolff, Michael T.; Cheatham, Diana M.; Iwakiri, Wataru; Gottlieb, Amy M.; Falkner, Sebastian; Ballhausen, Ralf; Fuerst, Felix; Kuehnel, Matthias; Ferrigno, Carlo; Becker, Peter A.; Wood, Kent S.; Wilms, Joern

    2018-01-01

    A new window for better understanding the accretion onto strongly magnetized neutron stars in X-ray binaries is opening. In these systems the accreted material follows the magnetic field lines as it approaches the neutron star, forming accretion columns above the magnetic poles. The plasma falls toward the neutron star surface at near-relativistic speeds, losing energy by emitting X-rays. The X-ray spectral continua are commonly described using phenomenological models, i.e., power laws with different types of curved cut-offs at higher energies. Here we consider high luminosity pulsars. In these systems the mass transfer rate is high enough that the accreting plasma is thought to be decelerated in a radiation-dominated radiative shock in the accretion columns. While the theory of the emission from such shocks had already been developed by 2007, a model for direct comparison with X-ray continuum spectra in xspec or isis has only recently become available. Characteristic parameters of this model are the accretion column radius and the plasma temperature, among others. Here we analyze the broadband X-ray spectra of the accreting pulsars Centaurus X-3 and 4U 1626-67 obtained with NuSTAR. We present results from traditional empirical modeling as well as successfully apply the radiation-dominated radiative shock model. We also take the opportunity to compare to similar recent analyses of both sources using these and other observations.

  8. A Novel Dynamic Model Describing the Spread of the MERS-CoV and the Expression of Dipeptidyl Peptidase 4

    Directory of Open Access Journals (Sweden)

    Siming Tang

    2017-01-01

    Full Text Available The Middle East respiratory syndrome (MERS coronavirus, a newly identified pathogen, causes severe pneumonia in humans. MERS is caused by a coronavirus known as MERS-CoV, which attacks the respiratory system. The recently defined receptor for MERS-CoV, dipeptidyl peptidase 4 (DPP4, is generally expressed in endothelial and epithelial cells and has been shown to be present on cultured human nonciliated bronchiolar epithelium cells. In this paper, a class of novel four-dimensional dynamic model describing the infection of MERS-CoV is given, and then global stability of the equilibria of the model is discussed. Our results show that the spread of MERS-CoV can also be controlled by decreasing the expression rate of DPP4.

  9. A mathematical model describing the glycemic response of diabetic patients to meal and i.v. infusion of insulin.

    Science.gov (United States)

    Fabietti, P G; Calabrese, G; Iorio, M; Bistoni, S; Brunetti, P; Sarti, E; Benedetti, M M

    2001-10-01

    Nine type 1 diabetic patients were studied for 24 hours. During this period they were given three calibrated meals. The glycemia was feedback-controlled by means of an artificial pancreas. The blood concentration of glucose and the infusion speed of the insulin were measured every minute. The experimental data referring to each of the three meals were used to estimate the parameters of a mathematical model suitable for describing the glycemic response of diabetic patients at meals and at the i.v. infusion of exogenous insulin. From the estimate a marked dispersion of the parameters was found, both interindividual and intraindividual. Nevertheless the models thus obtained seem to be usable for the synthesis of a feedback controller, especially in view of creating a portable artificial pancreas that now seems possible owing to the realization (so far experimental) of sufficiently reliable glucose concentration sensors.

  10. An analytical mechanical model to describe the response of NiTi rotary endodontic files in a curved root canal.

    Science.gov (United States)

    Leroy, Agnès Marie Françoise; Bahia, Maria Guiomar de Azevedo; Ehrlacher, Alain; Buono, Vicente Tadeu Lopes

    2012-08-01

    To build a mathematical model describing the mechanical behavior of NiTi rotary files while they are rotating in a root canal. The file was seen as a beam undergoing large transformations. The instrument was assumed to be rotating steadily in the root canal, and the geometry of the canal was considered as a known parameter of the problem. The formulae of large transformations mechanics then allowed the calculation of the Green-Lagrange strain field in the file. The non-linear mechanical behavior of NiTi was modeled as a continuous piecewise linear function, assuming that the material did not reach plastic deformation. Criteria locating the changes of behavior of NiTi were established and the tension field in the file, and the external efforts applied on it were calculated. The unknown variable of torsion was deduced from the equilibrium equation system using a Coulomb contact law which solved the problem on a cycle of rotation. In order to verify that the model described well reality, three-point bending experiments were managed on superelastic NiTi wires, whose results were compared to the theoretical ones. It appeared that the model gave a good mentoring of the empirical results in the range of bending angles that interested us. Knowing the geometry of the root canal, one is now able to write the equations of the strain and stress fields in the endodontic instrument, and to quantify the impact of each macroscopic parameter of the problem on its response. This should be useful to predict failure of the files under rotating bending fatigue, and to optimize the geometry of the files. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. An analytical mechanical model to describe the response of NiTi rotary endodontic files in a curved root canal

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, Agnes Marie Francoise [Department of Metallurgical and Materials Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Department of Mechanical and Materials Engineering, Ecole des Ponts Paristech (ENPC), Champs-sur-Marne (France); Bahia, Maria Guiomar de Azevedo [Department of Restorative Dentistry, Faculty of Dentistry, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Ehrlacher, Alain [Department of Mechanical and Materials Engineering, Ecole des Ponts Paristech (ENPC), Champs-sur-Marne (France); Buono, Vicente Tadeu Lopes, E-mail: vbuono@demet.ufmg.br [Department of Metallurgical and Materials Engineering, School of Engineering, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2012-08-01

    Aim: To build a mathematical model describing the mechanical behavior of NiTi rotary files while they are rotating in a root canal. Methodology: The file was seen as a beam undergoing large transformations. The instrument was assumed to be rotating steadily in the root canal, and the geometry of the canal was considered as a known parameter of the problem. The formulae of large transformations mechanics then allowed the calculation of the Green-Lagrange strain field in the file. The non-linear mechanical behavior of NiTi was modeled as a continuous piecewise linear function, assuming that the material did not reach plastic deformation. Criteria locating the changes of behavior of NiTi were established and the tension field in the file, and the external efforts applied on it were calculated. The unknown variable of torsion was deduced from the equilibrium equation system using a Coulomb contact law which solved the problem on a cycle of rotation. Results: In order to verify that the model described well reality, three-point bending experiments were managed on superelastic NiTi wires, whose results were compared to the theoretical ones. It appeared that the model gave a good mentoring of the empirical results in the range of bending angles that interested us. Conclusions: Knowing the geometry of the root canal, one is now able to write the equations of the strain and stress fields in the endodontic instrument, and to quantify the impact of each macroscopic parameter of the problem on its response. This should be useful to predict failure of the files under rotating bending fatigue, and to optimize the geometry of the files. - Highlights: Black-Right-Pointing-Pointer A mechanical model of the behavior of a NiTi endodontic instrument was developed. Black-Right-Pointing-Pointer The model was validated with results of three-point bending tests on NiTi wires. Black-Right-Pointing-Pointer The model is appropriate for the optimization of instruments' geometry.

  12. A two-phase model to describe the dissolution of ZrO2 by molten Zr

    International Nuclear Information System (INIS)

    Belloni, J.; Fichot, F.; Goyeau, B.; Gobin, D.; Quintard, M.

    2007-01-01

    In case of a hypothetical severe accident in a nuclear Pressurized Water Reactor (PWR), the fuel elements in the core may reach very high temperatures (more than 2000 K). UO 2 (Uranium dioxide) pellets are enclosed by a cladding mainly composed of Zircaloy (Zr). If the temperature became higher than 2100 K (melting temperature of Zr), the UO 2 pellets would be in contact with molten Zr, resulting in the dissolution and liquefaction of UO 2 at a lower temperature than its melting points (3100 K). Several experimental and numerical investigations have led to a better understanding of this phenomenon but a comprehensive and consistent modeling is still missing. The goal of this paper is to propose a two-phase macroscopic model describing the dissolution of a solid alloy by a liquid. The model is limited to binary alloys and it is applied to the particular case of the dissolution of ZrO 2 by liquid Zr, for which experimental data are available (Hofmann et al., 1999). The model was established by using a volume averaging method. Numerical simulations are compared to experimental results and show a good agreement. (authors)

  13. QSAR models for describing the toxicological effects of ILs against Staphylococcus aureus based on norm indexes.

    Science.gov (United States)

    He, Wensi; Yan, Fangyou; Jia, Qingzhu; Xia, Shuqian; Wang, Qiang

    2018-03-01

    The hazardous potential of ionic liquids (ILs) is becoming an issue of great concern due to their important role in many industrial fields as green agents. The mathematical model for the toxicological effects of ILs is useful for the risk assessment and design of environmentally benign ILs. The objective of this work is to develop QSAR models to describe the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of ILs against Staphylococcus aureus (S. aureus). A total of 169 and 101 ILs with MICs and MBCs, respectively, are used to obtain multiple linear regression models based on matrix norm indexes. The norm indexes used in this work are proposed by our research group and they are first applied to estimate the antibacterial toxicity of these ILs against S. aureus. These two models precisely and reliably calculated the IL toxicities with a square of correlation coefficient (R 2 ) of 0.919 and a standard error of estimate (SE) of 0.341 (in log unit of mM) for pMIC, and an R 2 of 0.913 and SE of 0.282 for pMBC. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Qualitative modeling of the dynamics of detonations with losses

    KAUST Repository

    Faria, Luiz; Kasimov, Aslan R.

    2015-01-01

    We consider a simplified model for the dynamics of one-dimensional detonations with generic losses. It consists of a single partial differential equation that reproduces, at a qualitative level, the essential properties of unsteady detonation waves, including pulsating and chaotic solutions. In particular, we investigate the effects of shock curvature and friction losses on detonation dynamics. To calculate steady-state solutions, a novel approach to solving the detonation eigenvalue problem is introduced that avoids the well-known numerical difficulties associated with the presence of a sonic point. By using unsteady numerical simulations of the simplified model, we also explore the nonlinear stability of steady-state or quasi-steady solutions. © 2014 The Combustion Institute.

  15. Numerical Modeling Describing the Effects of Heterogeneous Distributions of Asperities on the Quasi-static Evolution of Frictional Slip

    Science.gov (United States)

    Selvadurai, P. A.; Parker, J. M.; Glaser, S. D.

    2017-12-01

    A better understanding of how slip accumulates along faults and its relation to the breakdown of shear stress is beneficial to many engineering disciplines, such as, hydraulic fracture and understanding induced seismicity (among others). Asperities forming along a preexisting fault resist the relative motion of the two sides of the interface and occur due to the interaction of the surface topographies. Here, we employ a finite element model to simulate circular partial slip asperities along a nominally flat frictional interface. Shear behavior of our partial slip asperity model closely matched the theory described by Cattaneo. The asperity model was employed to simulate a small section of an experimental fault formed between two bodies of polymethyl methacrylate, which consisted of multiple asperities whose location and sizes were directly measured using a pressure sensitive film. The quasi-static shear behavior of the interface was modeled for cyclical loading conditions, and the frictional dissipation (hysteresis) was normal stress dependent. We further our understanding by synthetically modeling lognormal size distributions of asperities that were randomly distributed in space. Synthetic distributions conserved the real contact area and aspects of the size distributions from the experimental case, allowing us to compare the constitutive behaviors based solely on spacing effects. Traction-slip behavior of the experimental interface appears to be considerably affected by spatial clustering of asperities that was not present in the randomly spaced, synthetic asperity distributions. Estimates of bulk interfacial shear stiffness were determined from the constitutive traction-slip behavior and were comparable to the theoretical estimates of multi-contact interfaces with non-interacting asperities.

  16. Indirect estimation of the Convective Lognormal Transfer function model parameters for describing solute transport in unsaturated and undisturbed soil.

    Science.gov (United States)

    Mohammadi, Mohammad Hossein; Vanclooster, Marnik

    2012-05-01

    Solute transport in partially saturated soils is largely affected by fluid velocity distribution and pore size distribution within the solute transport domain. Hence, it is possible to describe the solute transport process in terms of the pore size distribution of the soil, and indirectly in terms of the soil hydraulic properties. In this paper, we present a conceptual approach that allows predicting the parameters of the Convective Lognormal Transfer model from knowledge of soil moisture and the Soil Moisture Characteristic (SMC), parameterized by means of the closed-form model of Kosugi (1996). It is assumed that in partially saturated conditions, the air filled pore volume act as an inert solid phase, allowing the use of the Arya et al. (1999) pragmatic approach to estimate solute travel time statistics from the saturation degree and SMC parameters. The approach is evaluated using a set of partially saturated transport experiments as presented by Mohammadi and Vanclooster (2011). Experimental results showed that the mean solute travel time, μ(t), increases proportionally with the depth (travel distance) and decreases with flow rate. The variance of solute travel time σ²(t) first decreases with flow rate up to 0.4-0.6 Ks and subsequently increases. For all tested BTCs predicted solute transport with μ(t) estimated from the conceptual model performed much better as compared to predictions with μ(t) and σ²(t) estimated from calibration of solute transport at shallow soil depths. The use of μ(t) estimated from the conceptual model therefore increases the robustness of the CLT model in predicting solute transport in heterogeneous soils at larger depths. In view of the fact that reasonable indirect estimates of the SMC can be made from basic soil properties using pedotransfer functions, the presented approach may be useful for predicting solute transport at field or watershed scales. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Gaze patterns reveal how texts are remembered: A mental model of what was described is favored over the text itself

    DEFF Research Database (Denmark)

    Traub, Franziska; Johansson, Roger; Holmqvist, Kenneth

    or incongruent with the spatial layout of the text itself. 28 participants read and recalled three texts: (1) a scene description congruent with the spatial layout of the text; (2) a scene description incongruent with the spatial layout of the text; and (3) a control text without any spatial scene content....... Recollection was performed orally while gazing at a blank screen. 
Results demonstrate that participant’s gaze patterns during recall more closely reflect the spatial layout of the scene than the physical locations of the text. We conclude that participants formed a mental model that represents the content...... of what was described, i.e., visuospatial information of the scene, which then guided the retrieval process. During their retellings, they moved the eyes across the blank screen as if they saw the scene in front of them. Whereas previous studies on the involvement of eye movements in mental imagery tasks...

  18. Universal free school breakfast: a qualitative model for breakfast behaviors

    Directory of Open Access Journals (Sweden)

    Louise eHarvey-Golding

    2015-06-01

    Full Text Available In recent years the provision of school breakfast has increased significantly in the UK. However, research examining the effectiveness of school breakfast is still within relative stages of infancy, and findings to date have been rather mixed. Moreover, previous evaluations of school breakfast schemes have been predominantly quantitative in their methodologies. Presently there are few qualitative studies examining the subjective perceptions and experiences of stakeholders, and thereby an absence of knowledge regarding the sociocultural impacts of school breakfast. The purpose of this study was to investigate the beliefs, views and attitudes, and breakfast consumption behaviors, among key stakeholders, served by a council-wide universal free school breakfast initiative, within the North West of England, UK. A sample of children, parents and school staff were recruited from three primary schools, participating in the universal free school breakfast scheme, to partake in semi-structured interviews and small focus groups. A Grounded Theory analysis of the data collected identified a theoretical model of breakfast behaviors, underpinned by the subjective perceptions and experiences of these key stakeholders. The model comprises of three domains relating to breakfast behaviors, and the internal and external factors that are perceived to influence breakfast behaviors, among children, parents and school staff. Findings were validated using triangulation methods, member checks and inter-rater reliability measures. In presenting this theoretically grounded model for breakfast behaviors, this paper provides a unique qualitative insight into the breakfast consumption behaviors and barriers to breakfast consumption, within a socioeconomically deprived community, participating in a universal free school breakfast intervention program.

  19. Marquardt's Phi mask: pitfalls of relying on fashion models and the golden ratio to describe a beautiful face.

    Science.gov (United States)

    Holland, E

    2008-03-01

    Stephen Marquardt has derived a mask from the golden ratio that he claims represents the "ideal" facial archetype. Many have found his mask convincing, including cosmetic surgeons. However, Marquardt's mask is associated with numerous problems. The method used to examine goodness of fit with the proportions in the mask is faulty. The mask is ill-suited for non-European populations, especially sub-Saharan Africans and East Asians. The mask also appears to approximate the face shape of masculinized European women. Given that the general public strongly and overwhelmingly prefers above average facial femininity in women, white women seeking aesthetic facial surgery would be ill-advised to aim toward a better fit with Marquardt's mask. This article aims to show the proper way of assessing goodness of fit with Marquardt's mask, to address the shape of the mask as it pertains to masculinity-femininity, and to discuss the broader issue of an objective assessment of facial attractiveness. Generalized Procrustes analysis is used to show how goodness of fit with Marquardt's mask can be assessed. Thin-plate spline analysis is used to illustrate visually how sample faces, including northwestern European averages, differ from Marquardt's mask. Marquardt's mask best describes the facial proportions of masculinized white women as seen in fashion models. Marquardt's mask does not appear to describe "ideal" face shape even for white women because its proportions are inconsistent with the optimal preferences of most people, especially with regard to femininity.

  20. Can model Hamiltonians describe the electron–electron interaction in π-conjugated systems?: PAH and graphene

    International Nuclear Information System (INIS)

    Chiappe, G; Louis, E; San-Fabián, E; Vergés, J A

    2015-01-01

    Model Hamiltonians have been, and still are, a valuable tool for investigating the electronic structure of systems for which mean field theories work poorly. This review will concentrate on the application of Pariser–Parr–Pople (PPP) and Hubbard Hamiltonians to investigate some relevant properties of polycyclic aromatic hydrocarbons (PAH) and graphene. When presenting these two Hamiltonians we will resort to second quantisation which, although not the way chosen in its original proposal of the former, is much clearer. We will not attempt to be comprehensive, but rather our objective will be to try to provide the reader with information on what kinds of problems they will encounter and what tools they will need to solve them. One of the key issues concerning model Hamiltonians that will be treated in detail is the choice of model parameters. Although model Hamiltonians reduce the complexity of the original Hamiltonian, they cannot be solved in most cases exactly. So, we shall first consider the Hartree–Fock approximation, still the only tool for handling large systems, besides density functional theory (DFT) approaches. We proceed by discussing to what extent one may exactly solve model Hamiltonians and the Lanczos approach. We shall describe the configuration interaction (CI) method, a common technology in quantum chemistry but one rarely used to solve model Hamiltonians. In particular, we propose a variant of the Lanczos method, inspired by CI, that has the novelty of using as the seed of the Lanczos process a mean field (Hartree–Fock) determinant (the method will be named LCI). Two questions of interest related to model Hamiltonians will be discussed: (i) when including long-range interactions, how crucial is including in the Hamiltonian the electronic charge that compensates ion charges? (ii) Is it possible to reduce a Hamiltonian incorporating Coulomb interactions (PPP) to an ‘effective’ Hamiltonian including only on-site interactions (Hubbard)? The

  1. Accounting for parameter uncertainty in the definition of parametric distributions used to describe individual patient variation in health economic models

    Directory of Open Access Journals (Sweden)

    Koen Degeling

    2017-12-01

    Full Text Available Abstract Background Parametric distributions based on individual patient data can be used to represent both stochastic and parameter uncertainty. Although general guidance is available on how parameter uncertainty should be accounted for in probabilistic sensitivity analysis, there is no comprehensive guidance on reflecting parameter uncertainty in the (correlated parameters of distributions used to represent stochastic uncertainty in patient-level models. This study aims to provide this guidance by proposing appropriate methods and illustrating the impact of this uncertainty on modeling outcomes. Methods Two approaches, 1 using non-parametric bootstrapping and 2 using multivariate Normal distributions, were applied in a simulation and case study. The approaches were compared based on point-estimates and distributions of time-to-event and health economic outcomes. To assess sample size impact on the uncertainty in these outcomes, sample size was varied in the simulation study and subgroup analyses were performed for the case-study. Results Accounting for parameter uncertainty in distributions that reflect stochastic uncertainty substantially increased the uncertainty surrounding health economic outcomes, illustrated by larger confidence ellipses surrounding the cost-effectiveness point-estimates and different cost-effectiveness acceptability curves. Although both approaches performed similar for larger sample sizes (i.e. n = 500, the second approach was more sensitive to extreme values for small sample sizes (i.e. n = 25, yielding infeasible modeling outcomes. Conclusions Modelers should be aware that parameter uncertainty in distributions used to describe stochastic uncertainty needs to be reflected in probabilistic sensitivity analysis, as it could substantially impact the total amount of uncertainty surrounding health economic outcomes. If feasible, the bootstrap approach is recommended to account for this uncertainty.

  2. Accounting for parameter uncertainty in the definition of parametric distributions used to describe individual patient variation in health economic models.

    Science.gov (United States)

    Degeling, Koen; IJzerman, Maarten J; Koopman, Miriam; Koffijberg, Hendrik

    2017-12-15

    Parametric distributions based on individual patient data can be used to represent both stochastic and parameter uncertainty. Although general guidance is available on how parameter uncertainty should be accounted for in probabilistic sensitivity analysis, there is no comprehensive guidance on reflecting parameter uncertainty in the (correlated) parameters of distributions used to represent stochastic uncertainty in patient-level models. This study aims to provide this guidance by proposing appropriate methods and illustrating the impact of this uncertainty on modeling outcomes. Two approaches, 1) using non-parametric bootstrapping and 2) using multivariate Normal distributions, were applied in a simulation and case study. The approaches were compared based on point-estimates and distributions of time-to-event and health economic outcomes. To assess sample size impact on the uncertainty in these outcomes, sample size was varied in the simulation study and subgroup analyses were performed for the case-study. Accounting for parameter uncertainty in distributions that reflect stochastic uncertainty substantially increased the uncertainty surrounding health economic outcomes, illustrated by larger confidence ellipses surrounding the cost-effectiveness point-estimates and different cost-effectiveness acceptability curves. Although both approaches performed similar for larger sample sizes (i.e. n = 500), the second approach was more sensitive to extreme values for small sample sizes (i.e. n = 25), yielding infeasible modeling outcomes. Modelers should be aware that parameter uncertainty in distributions used to describe stochastic uncertainty needs to be reflected in probabilistic sensitivity analysis, as it could substantially impact the total amount of uncertainty surrounding health economic outcomes. If feasible, the bootstrap approach is recommended to account for this uncertainty.

  3. A one-dimensional model to describe flow localization in viscoplastic slender bars subjected to super critical impact velocities

    Science.gov (United States)

    Vaz-Romero, A.; Rodríguez-Martínez, J. A.

    2018-01-01

    In this paper we investigate flow localization in viscoplastic slender bars subjected to dynamic tension. We explore loading rates above the critical impact velocity: the wave initiated in the impacted end by the applied velocity is the trigger for the localization of plastic deformation. The problem has been addressed using two kinds of numerical simulations: (1) one-dimensional finite difference calculations and (2) axisymmetric finite element computations. The latter calculations have been used to validate the capacity of the finite difference model to describe plastic flow localization at high impact velocities. The finite difference model, which highlights due to its simplicity, allows to obtain insights into the role played by the strain rate and temperature sensitivities of the material in the process of dynamic flow localization. Specifically, we have shown that viscosity can stabilize the material behavior to the point of preventing the appearance of the critical impact velocity. This is a key outcome of our investigation, which, to the best of the authors' knowledge, has not been previously reported in the literature.

  4. Application of inverse modeling technique to describe hydrogeochemical processes responsible to spatial distribution of groundwater quality along flowpath

    Directory of Open Access Journals (Sweden)

    Tjahyo NugrohoAdji

    2013-07-01

    The result shows that firstly, the aquifer within the research area can be grouped into several aquifer systems (i.e. denudational hill, colluvial plain, alluvial plain, and beach ridges from recharge to discharge which generally have potential groundwater resources in terms of the depth and fluctuation of groundwater table. Secondly, flownets analysis gives three flowpaths that are plausible to be modeled in order to describe their hydrogeochemical reactions. Thirdly, the Saturation Indices (SI analysis shows that there are a positive correlation between the mineral occurrence and composition and the value of SI from recharge to discharge. In addition, The Mass Balance Model indicates that dissolution and precipitation of aquifer minerals is dominantly change the chemical composition along flowpath and the rate of the mass transfer between two wells shows a discrepancy and be certain of the percentage of the nature of aquifer mineral. Lastly, there is an interesting characteristic of mass balance chemical reaction occurs which is the entire chemical reaction shows that the sum of smallest mineral fmmol/litre will firstly always totally be reacted.

  5. Models describing mackerel (Scomber scombrus early life growth in the North and Northwest of the Iberian Peninsula in 2000

    Directory of Open Access Journals (Sweden)

    Begoña Villamor

    2004-12-01

    Full Text Available Mackerel (Scomber scombrus in early life stages were captured in 2000 in the north and northwest of the Iberian Peninsula (ICES Divisions VIIIc and IXa North. Daily rings on their otolith sagittae were identified. Otoliths from 377 larvae and post-larvae caught in April and May 2000, ranging in length from 2.3 to 23.7 mm LS (Standard length and ranging in age from 7 to 38 days after hatching were analysed. Additionally, 68 otoliths from juveniles and pre-recruits caught between July and October 2000 with a length range of 121-202 mm LS and aged between 65-186 days after hatching were analysed. Gompertz and Logistic growth models were fitted to the pooled length at age data of the larvae-postlarvae and juveniles-pre-recruits. As length at hatch is assumed in the literature to be 3.0 mm, the models were applied in two ways; not forced to pass through L0=3.0 mm and forced to pass through L0=3.0 mm. The unforced logistic growth curve appeared to be the most suitable for describing growth during the first year of life of mackerel (L? = 191.6 mm; K= 0.070; t0= 66.7 d.

  6. An extended model based on the modified Nernst-Planck equation for describing transdermal iontophoresis of weak electrolytes.

    Science.gov (United States)

    Imanidis, Georgios; Luetolf, Peter

    2006-07-01

    An extended model for iontophoretic enhancement of transdermal drug permeation under constant voltage is described based on the previously modified Nernst-Planck equation, which included the effect of convective solvent flow. This model resulted in an analytical expression for the enhancement factor as a function of applied voltage, convective flow velocity due to electroosmosis, ratio of lipid to aqueous pathway passive permeability, and weighted average net ionic valence of the permeant in the aqueous epidermis domain. The shift of pH in the epidermis compared to bulk caused by the electrical double layer at the lipid-aqueous domain interface was evaluated using the Poisson-Boltzmann equation. This was solved numerically for representative surface charge densities and yielded pH differences between bulk and epidermal aqueous domain between 0.05 and 0.4 pH units. The developed model was used to analyze the experimental enhancement of an amphoteric weak electrolyte measured in vitro using human cadaver epidermis and a voltage of 250 mV at different pH values. Parameter values characterizing the involved factors were determined that yielded the experimental enhancement factors and passive permeability coefficients at all pH values. The model provided a very good agreement between experimental and calculated enhancement and passive permeability. The deduced parameters showed (i) that the pH shift in the aqueous permeation pathway had a notable effect on the ionic valence and the partitioning of the drug in this domain for a high surface charge density and depending on the pK(a) and pI of the drug in relation to the bulk pH; (ii) the magnitude and the direction of convective transport due to electroosmosis typically reflected the density and sign, respectively, of surface charge of the tissue and its effect on enhancement was substantial for bulk pH values differing from the pI of epidermal tissue; (iii) the aqueous pathway predominantly determined passive

  7. Learning about Ecological Systems by Constructing Qualitative Models with DynaLearn

    Science.gov (United States)

    Leiba, Moshe; Zuzovsky, Ruth; Mioduser, David; Benayahu, Yehuda; Nachmias, Rafi

    2012-01-01

    A qualitative model of a system is an abstraction that captures ordinal knowledge and predicts the set of qualitatively possible behaviours of the system, given a qualitative description of its structure and initial state. This paper examines an innovative approach to science education using an interactive learning environment that supports…

  8. Impact of environmental factors in home rehabilitation--a qualitative study from the perspective of older persons using the International Classification of Functioning, Disability and Health to describe facilitators and barriers.

    Science.gov (United States)

    Randström, Kerstin Björkman; Asplund, Kenneth; Svedlund, Marianne

    2012-01-01

    The aim of this study was to explore older people's experience of environmental factors that impact on their activity and participation in home rehabilitation. Older people aged between 68 and 93 years and receiving home rehabilitation were interviewed. A qualitative content analysis was performed on the interview text using the predetermined structure of the International Classification of Functioning, Disability and Health (ICF) environmental domain. The text was linked to the closest ICF category. The results identified environmental facilitators and barriers that influenced activity and participation among older people receiving home rehabilitation. Approaches that provided a facilitative environment were access to assistive products and technologies, alterations to the physical environment, social support and relationships, and adjusted health and social care services. A qualitative study using ICF-listed environmental factors contributed a holistic view of facilitators and barriers in home rehabilitation for older people. Awareness of the importance of the impact of the social environment on activities and participation could improve home rehabilitation services for older people. The study represents an important step towards a holistic approach using the ICF, which aims to enable all health care professionals to describe, plan and evaluate rehabilitation services together with older people across the health and social care sectors.

  9. The Maudsley Model of Family-Based Treatment for Anorexia Nervosa: A Qualitative Evaluation of Parent-to-Parent Consultation

    Science.gov (United States)

    Rhodes, Paul; Brown, Jac; Madden, Sloane

    2009-01-01

    This article describes the qualitative analysis of a randomized control trial that explores the use of parent-to-parent consultations as an augmentation to the Maudsley model of family-based treatment for anorexia. Twenty families were randomized into two groups, 10 receiving standard treatment and 10 receiving an additional parent-to-parent…

  10. A physically-based analytical model to describe effective excess charge for streaming potential generation in saturated porous media

    Science.gov (United States)

    Jougnot, D.; Guarracino, L.

    2016-12-01

    The self-potential (SP) method is considered by most researchers the only geophysical method that is directly sensitive to groundwater flow. One source of SP signals, the so-called streaming potential, results from the presence of an electrical double layer at the mineral-pore water interface. When water flows through the pore space, it gives rise to a streaming current and a resulting measurable electrical voltage. Different approaches have been proposed to predict streaming potentials in porous media. One approach is based on the excess charge which is effectively dragged in the medium by the water flow. Following a recent theoretical framework, we developed a physically-based analytical model to predict the effective excess charge in saturated porous media. In this study, the porous media is described by a bundle of capillary tubes with a fractal pore-size distribution. First, an analytical relationship is derived to determine the effective excess charge for a single capillary tube as a function of the pore water salinity. Then, this relationship is used to obtain both exact and approximated expressions for the effective excess charge at the Representative Elementary Volume (REV) scale. The resulting analytical relationship allows the determination of the effective excess charge as a function of pore water salinity, fractal dimension and hydraulic parameters like porosity and permeability, which are also obtained at the REV scale. This new model has been successfully tested against data from the literature of different sources. One of the main finding of this study is that it provides a mechanistic explanation to the empirical dependence between the effective excess charge and the permeability that has been found by various researchers. The proposed petrophysical relationship also contributes to understand the role of porosity and water salinity on effective excess charge and will help to push further the use of streaming potential to monitor groundwater flow.

  11. Mechanisms for improving mass transfer in food with ultrasound technology: Describing the phenomena in two model cases.

    Science.gov (United States)

    Miano, Alberto Claudio; Ibarz, Albert; Augusto, Pedro Esteves Duarte

    2016-03-01

    The aim of this work was to demonstrate how ultrasound mechanisms (direct and indirect effects) improve the mass transfer phenomena in food processing, and which part of the process they are more effective in. Two model cases were evaluated: the hydration of sorghum grain (with two water activities) and the influx of a pigment into melon cylinders. Different treatments enabled us to evaluate and discriminate both direct (inertial flow and "sponge effect") and indirect effects (micro channel formation), alternating pre-treatments and treatments using an ultrasonic bath (20 kHz of frequency and 28 W/L of volumetric power) and a traditional water-bath. It was demonstrated that both the effects of ultrasound technology are more effective in food with higher water activity, the micro channels only forming in moist food. Moreover, micro channel formation could also be observed using agar gel cylinders, verifying the random formation of these due to cavitation. The direct effects were shown to be important in mass transfer enhancement not only in moist food, but also in dry food, this being improved by the micro channels formed and the porosity of the food. In conclusion, the improvement in mass transfer due to direct and indirect effects was firstly discriminated and described. It was proven that both phenomena are important for mass transfer in moist foods, while only the direct effects are important for dry foods. Based on these results, better processing using ultrasound technology can be obtained. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. One-dimensional Fermi accelerator model with moving wall described by a nonlinear van der Pol oscillator.

    Science.gov (United States)

    Botari, Tiago; Leonel, Edson D

    2013-01-01

    A modification of the one-dimensional Fermi accelerator model is considered in this work. The dynamics of a classical particle of mass m, confined to bounce elastically between two rigid walls where one is described by a nonlinear van der Pol type oscillator while the other one is fixed, working as a reinjection mechanism of the particle for a next collision, is carefully made by the use of a two-dimensional nonlinear mapping. Two cases are considered: (i) the situation where the particle has mass negligible as compared to the mass of the moving wall and does not affect the motion of it; and (ii) the case where collisions of the particle do affect the movement of the moving wall. For case (i) the phase space is of mixed type leading us to observe a scaling of the average velocity as a function of the parameter (χ) controlling the nonlinearity of the moving wall. For large χ, a diffusion on the velocity is observed leading to the conclusion that Fermi acceleration is taking place. On the other hand, for case (ii), the motion of the moving wall is affected by collisions with the particle. However, due to the properties of the van der Pol oscillator, the moving wall relaxes again to a limit cycle. Such kind of motion absorbs part of the energy of the particle leading to a suppression of the unlimited energy gain as observed in case (i). The phase space shows a set of attractors of different periods whose basin of attraction has a complicated organization.

  13. An examination of qualitative plant modelling as a basis for knowledge-based operator aids in nuclear power stations

    International Nuclear Information System (INIS)

    Herbert, M.; Williams, G.

    1986-01-01

    New qualitative techniques for representing the behaviour of physical systems have recently been developed. These allow a qualitative representation to be formally derived from a quantitative plant model. One such technique, Incremental Qualitative Analysis, is based on manipulating qualitative differential equations, called confluences, using sign algebra. This is described and its potential for reducing the amount of information presented to the reactor operator is discussed. In order to illustrate the technique, a specific example relating to the influence of failures associated with a pressurized water reactor pressuriser is presented. It is shown that, although failures cannot necessarily be diagnosed unambiguously, the number of possible failures inferred is low. Techniques for discriminating between these possible failures are discussed. (author)

  14. Qualitative modeling of the decision-making process using electrooculography.

    Science.gov (United States)

    Zargari Marandi, Ramtin; Sabzpoushan, S H

    2015-12-01

    A novel method based on electrooculography (EOG) has been introduced in this work to study the decision-making process. An experiment was designed and implemented wherein subjects were asked to choose between two items from the same category that were presented within a limited time. The EOG and voice signals of the subjects were recorded during the experiment. A calibration task was performed to map the EOG signals to their corresponding gaze positions on the screen by using an artificial neural network. To analyze the data, 16 parameters were extracted from the response time and EOG signals of the subjects. Evaluation and comparison of the parameters, together with subjects' choices, revealed functional information. On the basis of this information, subjects switched their eye gazes between items about three times on average. We also found, according to statistical hypothesis testing-that is, a t test, t(10) = 71.62, SE = 1.25, p < .0001-that the correspondence rate of a subjects' gaze at the moment of selection with the selected item was significant. Ultimately, on the basis of these results, we propose a qualitative choice model for the decision-making task.

  15. Item response theory and structural equation modelling for ordinal data: Describing the relationship between KIDSCREEN and Life-H.

    Science.gov (United States)

    Titman, Andrew C; Lancaster, Gillian A; Colver, Allan F

    2016-10-01

    Both item response theory and structural equation models are useful in the analysis of ordered categorical responses from health assessment questionnaires. We highlight the advantages and disadvantages of the item response theory and structural equation modelling approaches to modelling ordinal data, from within a community health setting. Using data from the SPARCLE project focussing on children with cerebral palsy, this paper investigates the relationship between two ordinal rating scales, the KIDSCREEN, which measures quality-of-life, and Life-H, which measures participation. Practical issues relating to fitting models, such as non-positive definite observed or fitted correlation matrices, and approaches to assessing model fit are discussed. item response theory models allow properties such as the conditional independence of particular domains of a measurement instrument to be assessed. When, as with the SPARCLE data, the latent traits are multidimensional, structural equation models generally provide a much more convenient modelling framework. © The Author(s) 2013.

  16. Linear mixed-effects models to describe individual tree crown width for China-fir in Fujian Province, southeast China.

    Science.gov (United States)

    Hao, Xu; Yujun, Sun; Xinjie, Wang; Jin, Wang; Yao, Fu

    2015-01-01

    A multiple linear model was developed for individual tree crown width of Cunninghamia lanceolata (Lamb.) Hook in Fujian province, southeast China. Data were obtained from 55 sample plots of pure China-fir plantation stands. An Ordinary Linear Least Squares (OLS) regression was used to establish the crown width model. To adjust for correlations between observations from the same sample plots, we developed one level linear mixed-effects (LME) models based on the multiple linear model, which take into account the random effects of plots. The best random effects combinations for the LME models were determined by the Akaike's information criterion, the Bayesian information criterion and the -2logarithm likelihood. Heteroscedasticity was reduced by three residual variance functions: the power function, the exponential function and the constant plus power function. The spatial correlation was modeled by three correlation structures: the first-order autoregressive structure [AR(1)], a combination of first-order autoregressive and moving average structures [ARMA(1,1)], and the compound symmetry structure (CS). Then, the LME model was compared to the multiple linear model using the absolute mean residual (AMR), the root mean square error (RMSE), and the adjusted coefficient of determination (adj-R2). For individual tree crown width models, the one level LME model showed the best performance. An independent dataset was used to test the performance of the models and to demonstrate the advantage of calibrating LME models.

  17. Goals and Values in School: A Model Developed for Describing, Evaluating and Changing the Social Climate of Learning Environments

    Science.gov (United States)

    Allodi, Mara Westling

    2010-01-01

    This paper defines a broad model of the psychosocial climate in educational settings. The model was developed from a general theory of learning environments, on a theory of human values and on empirical studies of children's evaluations of their schools. The contents of the model are creativity, stimulation, achievement, self-efficacy, creativity,…

  18. Extension of the GroIMP modelling platform to allow easy specification of differential equations describing biological processes within plant models

    NARCIS (Netherlands)

    Hemmerling, R.; Evers, J.B.; Smolenova, K.; Buck-Sorlin, G.H.; Kurth, W.

    2013-01-01

    In simulation models of plant development, physiological processes taking place in plants are typically described in terms of ODEs (Ordinary Differential Equations). On the one hand, those processes drive the development of the plant structure and on the other hand, the developed structure again

  19. Probability of identification: a statistical model for the validation of qualitative botanical identification methods.

    Science.gov (United States)

    LaBudde, Robert A; Harnly, James M

    2012-01-01

    A qualitative botanical identification method (BIM) is an analytical procedure that returns a binary result (1 = Identified, 0 = Not Identified). A BIM may be used by a buyer, manufacturer, or regulator to determine whether a botanical material being tested is the same as the target (desired) material, or whether it contains excessive nontarget (undesirable) material. The report describes the development and validation of studies for a BIM based on the proportion of replicates identified, or probability of identification (POI), as the basic observed statistic. The statistical procedures proposed for data analysis follow closely those of the probability of detection, and harmonize the statistical concepts and parameters between quantitative and qualitative method validation. Use of POI statistics also harmonizes statistical concepts for botanical, microbiological, toxin, and other analyte identification methods that produce binary results. The POI statistical model provides a tool for graphical representation of response curves for qualitative methods, reporting of descriptive statistics, and application of performance requirements. Single collaborator and multicollaborative study examples are given.

  20. Development of a cloud microphysical model and parameterizations to describe the effect of CCN on warm cloud

    Directory of Open Access Journals (Sweden)

    N. Kuba

    2006-01-01

    Full Text Available First, a hybrid cloud microphysical model was developed that incorporates both Lagrangian and Eulerian frameworks to study quantitatively the effect of cloud condensation nuclei (CCN on the precipitation of warm clouds. A parcel model and a grid model comprise the cloud model. The condensation growth of CCN in each parcel is estimated in a Lagrangian framework. Changes in cloud droplet size distribution arising from condensation and coalescence are calculated on grid points using a two-moment bin method in a semi-Lagrangian framework. Sedimentation and advection are estimated in the Eulerian framework between grid points. Results from the cloud model show that an increase in the number of CCN affects both the amount and the area of precipitation. Additionally, results from the hybrid microphysical model and Kessler's parameterization were compared. Second, new parameterizations were developed that estimate the number and size distribution of cloud droplets given the updraft velocity and the number of CCN. The parameterizations were derived from the results of numerous numerical experiments that used the cloud microphysical parcel model. The input information of CCN for these parameterizations is only several values of CCN spectrum (they are given by CCN counter for example. It is more convenient than conventional parameterizations those need values concerned with CCN spectrum, C and k in the equation of N=CSk, or, breadth, total number and median radius, for example. The new parameterizations' predictions of initial cloud droplet size distribution for the bin method were verified by using the aforesaid hybrid microphysical model. The newly developed parameterizations will save computing time, and can effectively approximate components of cloud microphysics in a non-hydrostatic cloud model. The parameterizations are useful not only in the bin method in the regional cloud-resolving model but also both for a two-moment bulk microphysical model and

  1. A Conversational Model for Qualitative Research: A Case Study of Clergy and Religious Knowledge

    Science.gov (United States)

    Roland, Daniel; Wicks, Don A.

    2009-01-01

    This paper describes the qualitative research interview as a conversation designed to gain understanding of the world of research informants. It illustrates the potential of the qualitative research interview when the researcher is able to enter into and maintain a conversation with the research informant as an insider in the latter's community.…

  2. Environmental Consequences of Wildlife Tourism: The Use of Formalised Qualitative Models

    Directory of Open Access Journals (Sweden)

    Veselý Štěpán

    2015-09-01

    Full Text Available The paper presents a simple qualitative model of environmental consequences of wildlife tourism. Qualitative models use just three values: Positive/Increasing, Zero/Constant and Negative/Decreasing. Such quantifiers of trends are the least information intensive. Qualitative models can be useful, since models of wildlife tourism include such variables as, for example, Biodiversity (BIO, Animals’ habituation to tourists (HAB or Plant composition change (PLA that are sometimes difficult or costly to quantify. Hence, a significant fraction of available information about wildlife tourism and its consequences is not of numerical nature, for example, if HAB is increasing then BIO is decreasing. Such equationless relations are studied in this paper. The model has 10 variables and 20 equationless pairwise interrelations among them. The model is solved and 15 solutions, that is, scenarios are obtained. All qualitative states, including the first and second qualitative derivatives with respect to time, of all variables are specified for each scenario.

  3. Qualitative Content Analysis

    OpenAIRE

    Philipp Mayring

    2000-01-01

    The article describes an approach of systematic, rule guided qualitative text analysis, which tries to preserve some methodological strengths of quantitative content analysis and widen them to a concept of qualitative procedure. First the development of content analysis is delineated and the basic principles are explained (units of analysis, step models, working with categories, validity and reliability). Then the central procedures of qualitative content analysis, inductive development of ca...

  4. Challenges involved in the development of models describing the running hot of engines; Herausforderungen bei der Entwicklung von Motorwarmlaufmodellen

    Energy Technology Data Exchange (ETDEWEB)

    Unterguggenberger, Peter; Salbrechter, Sebastian; Jauk, Thomas; Wimmer, Andreas [Technische Univ. Graz (Austria). Inst. fuer Verbrennungskraftmaschinen und Thermodynamik (IVT)

    2012-11-01

    Currently, all potential must be tapped in order to reach the increasingly tighter CO{sub 2} limits for vehicles. From the variety of possible options for reducing fuel consumption, the contribution of improved heat management should not be ignored since increased friction during warm-up results in greater fuel consumption. Engine warm-up models that calculate thermal behavior and fuel consumption are a relatively inexpensive alternative to empirical measures. In order to achieve satisfactory simulation results, the exact modeling of thermal behavior as well as friction conditions is necessary. This paper identifies the demands placed on the individual submodels based on the requirements for precision that thermal warm-up models must meet. Before treating the friction model it will explain the development of the heat input model in detail. In addition, it presents the test program needed to establish and validate the simulation model with the required measurement accuracy. (orig.)

  5. A unified degree day model describes survivorship of Copitarsia corruda Pogue & Simmons (Lepidoptera: Noctuidae) at different constant temperatures

    Science.gov (United States)

    N.N. G& #243; mez; R.C. Venette; J.R. Gould; D.F. Winograd

    2009-01-01

    Predictions of survivorship are critical to quantify the probability of establishment by an alien invasive species, but survival curves rarely distinguish between the effects of temperature on development versus senescence. We report chronological and physiological age-based survival curves for a potentially invasive noctuid, recently described as Copitarsia...

  6. A qualitative reasoning model of algal bloom in the Danube Delta Biosphere Reserve (DDBR)

    NARCIS (Netherlands)

    Cioaca, E.; Linnebank, F.E.; Bredeweg, B.; Salles, P.

    2009-01-01

    This paper presents a Qualitative Reasoning model of the algal bloom phenomenon and its effects in the Danube Delta Biosphere Reserve (DDBR) in Romania. Qualitative Reasoning models represent processes and their cause-effect relationships in a flexible and conceptually rich manner and as such can be

  7. Development of a mathematical model describing hydrolysis and co-fermentation of C6 and C5 sugars

    DEFF Research Database (Denmark)

    Morales Rodriguez, Ricardo; Gernaey, Krist; Meyer, Anne S.

    2010-01-01

    saccharification and co-fermentation (SSCF) of C6 and C5 sugars. Model construction has been carried out by combining existing mathematical models for enzymatic hydrolysis on the one hand and co-fermentation on the other hand. An inhibition of ethanol on cellulose conversion was introduced in order to increase...

  8. Analytical model to describe the thermal behavior of a heat discharge system in roofs; Modelo analitico que describe el comportamiento termico de un sistema de descarga de calor en techos

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Gomez, V.H.; Contreras-Espinosa, J.J.; Gonzalez-Ortiz, G.; Morillon-Galvez, D.; Fernandez-Zayas, J.L. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)]. E-mail: vichugo@servidor.unam.mx; jjuancon2000@yahoo.com.mx; gilberto_gonzalez25@hotmail.com; damg@pumas.iingen.unam.mx; JFernandezZ@iingen.unam.mx

    2012-01-15

    The present study proposes an analytical model which describes the thermal behavior of a heat discharge system in roof, when the surfaces that constitute it are not translucent. Such a model derives from a thermal balance carried out to a heat discharge system in roofs. To validate it, an experimental prototype that allows simulating the thermal behavior of a heat discharge system in wall and roof was used, and the results were compared to those obtained with the proposed analytical model. It was found that the thermal behavior of the analytical model is similar to the thermal behavior of the experimental prototype; a worthless variation was detected among their respective outcome (The difference of temperatures can be caused by the heat transfer coefficient, of which no studies defining its behavior accurately have been found). Therefore, it can be considered that the proposed analytical model can be employed to simulate the thermal behavior of a heat discharge system in roofs when the surfaces that constitute it are opaque. [Spanish] En el presente estudio se propone un modelo analitico que describe el comportamiento termico de un sistema de descarga de calor en techo, cuando las superficies que lo componen no son translucidos. Dicho modelo surge a partir de un balance termico realizado a un sistema de descarga de calor en techos. Para validarlo, se realizaron dos corridas experimentales en un prototipo que permite simular el comportamiento termico de un sistema de descarga de calor en techo y se compararon los resultados medidos con los calculados por el modelo analitico propuesto. Se encontro que, el comportamiento termico del modelo analitico es similar al comportamiento termico del prototipo experimental, se detecto una variacion despreciable entre los valores arrojados por ambos modelos (la diferencia de temperaturas puede estar ocasionada por la obtencion del coeficiente convectivo de transferencia de calor, del cual no se han encontrado estudios que

  9. BLOW-3A. A theoretical model to describe transient two-phase flow conditions in LMFBR coolant channels

    International Nuclear Information System (INIS)

    Bottoni, M.; Struwe, D.

    1982-12-01

    The computer programme BLOW-3A describes sodium boiling phenomena in subassemblies of fast breeder reactors as well as in in-pile or out-of-pile experiments simulating different failure conditions. This report presents a complete documentation of the code from three main viewpoints: the theoretical foundations of the programme are first described with particular reference to the most recent developments; the structure of the programme is then explained in all details necessary for the user to get a rapid acquaintance with it; eventually several examples of the programme validation are discussed thus enabling the reader to acquire a full picture of the possible applications of the code and at the same time to know its validity range. (orig.) [de

  10. A qualitative model construction method of nuclear power plants for effective diagnostic knowledge generation

    International Nuclear Information System (INIS)

    Yoshikawa, Shinji; Endou, Akira; Kitamura, Yoshinobu; Sasajima, Munehiko; Ikeda, Mitsuru; Mizoguchi, Riichiro.

    1994-01-01

    This paper discusses a method to construct a qualitative model of a nuclear power plant, in order to generate effective diagnostic knowledge. The proposed method is to prepare deep knowledge to be provided to a knowledge compiler based upon qualitative reasoning (QR). Necessity of knowledge compilation for nuclear plant diagnosis will be explained first, and conventionally-experienced problems in qualitative reasoning and a proposed method to overcome this problem is shown next, then a sample procedure to build a qualitative nuclear plant model is demonstrated. (author)

  11. A Monte Carlo-adjusted goodness-of-fit test for parametric models describing spatial point patterns

    KAUST Repository

    Dao, Ngocanh; Genton, Marc G.

    2014-01-01

    Assessing the goodness-of-fit (GOF) for intricate parametric spatial point process models is important for many application fields. When the probability density of the statistic of the GOF test is intractable, a commonly used procedure is the Monte

  12. Study of market model describing the contrary behaviors of informed and uninformed agents: Being minority and being majority

    Science.gov (United States)

    Zhang, Yu-Xia; Liao, Hao; Medo, Matus; Shang, Ming-Sheng; Yeung, Chi Ho

    2016-05-01

    In this paper we analyze the contrary behaviors of the informed investors and uniformed investors, and then construct a competition model with two groups of agents, namely agents who intend to stay in minority and those who intend to stay in majority. We find two kinds of competitions, inter- and intra-groups. The model shows periodic fluctuation feature. The average distribution of strategies illustrates a prominent central peak which is relevant to the peak-fat-tail character of price change distribution in stock markets. Furthermore, in the modified model the tolerance time parameter makes the agents diversified. Finally, we compare the strategies distribution with the price change distribution in real stock market, and we conclude that contrary behavior rules and tolerance time parameter are indeed valid in the description of market model.

  13. The inverse Gamma process: A family of continuous stochastic models for describing state-dependent deterioration phenomena

    International Nuclear Information System (INIS)

    Guida, M.; Pulcini, G.

    2013-01-01

    This paper proposes the family of non-stationary inverse Gamma processes for modeling state-dependent deterioration processes with nonlinear trend. The proposed family of processes, which is based on the assumption that the “inverse” time process is Gamma, is mathematically more tractable than previously proposed state-dependent processes, because, unlike the previous models, the inverse Gamma process is a time-continuous and state-continuous model and does not require discretization of time and state. The conditional distribution of the deterioration growth over a generic time interval, the conditional distribution of the residual life and the residual reliability of the unit, given the current state, are provided. Point and interval estimation of the parameters which index the proposed process, as well as of several quantities of interest, are also discussed. Finally, the proposed model is applied to the wear process of the liners of some Diesel engines which was previously analyzed and proved to be a purely state-dependent process. The comparison of the inferential results obtained under the competitor models shows the ability of the Inverse Gamma process to adequately model the observed state-dependent wear process

  14. A model for describing the eutrophication in a heavily regulated coastal lagoon. Application to the Albufera of Valencia (Spain).

    Science.gov (United States)

    del Barrio Fernández, Pilar; Gómez, Andrés García; Alba, Javier García; Díaz, César Álvarez; Revilla Cortezón, José Antonio

    2012-12-15

    A simplified two-dimensional eutrophication model was developed to simulate temporal and spatial variations of chlorophyll-a in heavily regulated coastal lagoons. This model considers the hydrodynamics of the whole study area, the regulated connexion of the lagoon with the sea, the variability of the input and output nutrient loads, the flux from the sediments to the water column, the phytoplankton growth and mortality kinetics, and the zooplankton grazing. The model was calibrated and validated by applying it to the Albufera of Valencia, a hypertrophic system whose connection to the sea is strongly regulated by a system of sluice-gates. The calibration and validation results presented a significant agreement between the model and the data obtained in several surveys. The accuracy was evaluated using a quantitative analysis, in which the average uncertainty of the model prediction was less than 6%. The results confirmed an expected phytoplankton bloom in April and October, achieving mean maximum values around 250 μg l(-1) of chlorophyll-a. A mass balance revealed that the eutrophication process is magnified by the input loads of nutrients, mainly from the sediments, as well as by the limited connection of the lagoon with the sea. This study has shown that the developed model is an efficient tool to manage the eutrophication problem in heavily regulated coastal lagoons. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. A Physically Based Analytical Model to Describe Effective Excess Charge for Streaming Potential Generation in Water Saturated Porous Media

    Science.gov (United States)

    Guarracino, L.; Jougnot, D.

    2018-01-01

    Among the different contributions generating self-potential, the streaming potential is of particular interest in hydrogeology for its sensitivity to water flow. Estimating water flux in porous media using streaming potential data relies on our capacity to understand, model, and upscale the electrokinetic coupling at the mineral-solution interface. Different approaches have been proposed to predict streaming potential generation in porous media. One of these approaches is the flux averaging which is based on determining the excess charge which is effectively dragged in the medium by water flow. In this study, we develop a physically based analytical model to predict the effective excess charge in saturated porous media using a flux-averaging approach in a bundle of capillary tubes with a fractal pore size distribution. The proposed model allows the determination of the effective excess charge as a function of pore water ionic concentration and hydrogeological parameters like porosity, permeability, and tortuosity. The new model has been successfully tested against different set of experimental data from the literature. One of the main findings of this study is the mechanistic explanation to the empirical dependence between the effective excess charge and the permeability that has been found by several researchers. The proposed model also highlights the link to other lithological properties, and it is able to reproduce the evolution of effective excess charge with electrolyte concentrations.

  16. Amicus Plato, sed magis amica veritas: plots must obey the laws they refer to and models shall describe biophysical reality!

    Science.gov (United States)

    Katkov, Igor I

    2011-06-01

    In the companion paper, we discussed in details proper linearization, calculation of the inactive osmotic volume, and analysis of the results on the Boyle-vant' Hoff plots. In this Letter, we briefly address some common errors and misconceptions in osmotic modeling and propose some approaches, namely: (1) inapplicability of the Kedem-Katchalsky formalism model in regards to the cryobiophysical reality, (2) calculation of the membrane hydraulic conductivity L(p) in the presence of permeable solutes, (3) proper linearization of the Arrhenius plots for the solute membrane permeability, (4) erroneous use of the term "toxicity" for the cryoprotective agents, and (5) advantages of the relativistic permeability approach (RP) developed by us vs. traditional ("classic") 2-parameter model. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. On one peculiarity of the model describing the interaction of the electron beam with the semiconductor surface

    Science.gov (United States)

    Stepovich, M. A.; Amrastanov, A. N.; Seregina, E. V.; Filippov, M. N.

    2018-01-01

    The problem of heat distribution in semiconductor materials irradiated with sharply focused electron beams in the absence of heat exchange between the target and the external medium is considered by mathematical modeling methods. For a quantitative description of energy losses by probe electrons a model based on a separate description of the contributions of absorbed in the target and backscattered electrons and applicable to a wide class of solids and a range of primary electron energies is used. Using the features of this approach, the nonmonotonic dependence of the temperature of the maximum heating in the target on the energy of the primary electrons is explained. Some modeling results are illustrated for semiconductor materials of electronic engineering.

  18. A physics-based crystallographic modeling framework for describing the thermal creep behavior of Fe-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Wei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Capolungo, Laurent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Patra, Anirban [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tome, Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-02

    This Report addresses the Milestone M2MS-16LA0501032 of NEAMS Program (“Develop hardening model for FeCrAl cladding), with a deadline of 09/30/2016. Here we report a constitutive law for thermal creep of FeCrAl. This Report adds to and complements the one for Milestone M3MS-16LA0501034 (“Interface hardening models with MOOSE-BISON”), where we presented a hardening law for irradiated FeCrAl. The last component of our polycrystal-based constitutive behavior, namely, an irradiation creep model for FeCrAl, will be developed as part of the FY17 Milestones, and the three regimes will be coupled and interfaced with MOOSE-BISON.

  19. A toy model that predicts the qualitative role of bar bend in a push jerk.

    Science.gov (United States)

    Santos, Aaron; Meltzer, Norman E

    2009-11-01

    In this work, we describe a simple coarse-grained model of a barbell that can be used to determine the qualitative role of bar bend during a jerk. In simulations of this model, we observed a narrow time window during which the lifter can leverage the elasticity of the bar in order to lift the weight to a maximal height. This time window shifted to later times as the weight was increased. In addition, we found that the optimal time to initiate the drive was strongly correlated with the time at which the bar had reached a maximum upward velocity after recoiling. By isolating the effect of the bar, we obtained a generalized strategy for lifting heavy weight in the jerk.

  20. Evaluation of a cross contamination model describing transfer of Salmonella spp. and Listeria monocytogenes during grinding of pork and beef

    DEFF Research Database (Denmark)

    Møller, Cleide Oliveira de Almeida; Sant'Ana, A.S.; Hansen, Solvej Katrine Holm

    2016-01-01

    A cross contamination model was challenged and evaluated applying a new approach.•QMRA and Total Transfer Potential (TTP) were included.•Transfer estimates were not applicable for unlike processing.•The risk of disease may be reduced when using a stainless steel grinder.•Well-sharpened knife, and...

  1. A Strategy for Describing the Biosphere at Candidate Sites for Repositories of Nuclear Waste: Linking Ecosystem and Landscape Modeling

    International Nuclear Information System (INIS)

    Lindborg, Tobias; Loefgren, Anders; Soederbaeck, Bjoern; Kautsky, Ulrik; Lindborg, Regina; Bradshaw, Clare

    2006-01-01

    To provide information necessary for a license application for a deep repository for spent nuclear fuel, the Swedish Nuclear Fuel and Waste Management Co. has started site investigations at two sites in Sweden. In this paper, we present a strategy to integrate site-specific ecosystem data into spatially explicit models needed for safety assessment studies and the environmental impact assessment. The site-specific description of ecosystems is developed by building discipline-specific models from primary data and by identifying interactions and stocks and flows of matter among functional units at the sites. The conceptual model is a helpful initial tool for defining properties needed to quantify system processes, which may reveal new interfaces between disciplines, providing a variety of new opportunities to enhance the understanding of the linkages between ecosystem characteristics and the functional properties of landscapes. This type of integrated ecosystem-landscape characterization model has an important role in forming the implementation of a safety assessment for a deep repository

  2. QML-AiNet: An immune network approach to learning qualitative differential equation models.

    Science.gov (United States)

    Pang, Wei; Coghill, George M

    2015-02-01

    In this paper, we explore the application of Opt-AiNet, an immune network approach for search and optimisation problems, to learning qualitative models in the form of qualitative differential equations. The Opt-AiNet algorithm is adapted to qualitative model learning problems, resulting in the proposed system QML-AiNet. The potential of QML-AiNet to address the scalability and multimodal search space issues of qualitative model learning has been investigated. More importantly, to further improve the efficiency of QML-AiNet, we also modify the mutation operator according to the features of discrete qualitative model space. Experimental results show that the performance of QML-AiNet is comparable to QML-CLONALG, a QML system using the clonal selection algorithm (CLONALG). More importantly, QML-AiNet with the modified mutation operator can significantly improve the scalability of QML and is much more efficient than QML-CLONALG.

  3. Application of the NDHA model to describe N2O dynamics in activated sludge mixed culture biomass

    DEFF Research Database (Denmark)

    Domingo-Felez, Carlos; Smets, Barth F.

    A pseudo-mechanistic model describing three biological nitric oxide (NO) and nitrous oxide (N2O) production pathways was calibrated for an activated sludge mixed culture biomass treating municipal wastewater with laboratory-scale experiments. The model (NDHA) comprehensively describes N2O produci...

  4. Accounting for parameter uncertainty in the definition of parametric distributions used to describe individual patient variation in health economic models

    OpenAIRE

    Degeling, Koen; IJzerman, Maarten J.; Koopman, Miriam; Koffijberg, Hendrik

    2017-01-01

    Background Parametric distributions based on individual patient data can be used to represent both stochastic and parameter uncertainty. Although general guidance is available on how parameter uncertainty should be accounted for in probabilistic sensitivity analysis, there is no comprehensive guidance on reflecting parameter uncertainty in the (correlated) parameters of distributions used to represent stochastic uncertainty in patient-level models. This study aims to provide this guidance by ...

  5. Probability of Detection (POD) as a statistical model for the validation of qualitative methods.

    Science.gov (United States)

    Wehling, Paul; LaBudde, Robert A; Brunelle, Sharon L; Nelson, Maria T

    2011-01-01

    A statistical model is presented for use in validation of qualitative methods. This model, termed Probability of Detection (POD), harmonizes the statistical concepts and parameters between quantitative and qualitative method validation. POD characterizes method response with respect to concentration as a continuous variable. The POD model provides a tool for graphical representation of response curves for qualitative methods. In addition, the model allows comparisons between candidate and reference methods, and provides calculations of repeatability, reproducibility, and laboratory effects from collaborative study data. Single laboratory study and collaborative study examples are given.

  6. A Simple Model to Describe the Relationship among Rainfall, Groundwater and Land Subsidence under a Heterogeneous Aquifer

    Science.gov (United States)

    Zheng, Y. Y.; Chen, Y. L.; Lin, H. R.; Huang, S. Y.; Yeh, T. C. J.; Wen, J. C.

    2017-12-01

    Land subsidence is a very serious problem of Zhuoshui River alluvial fan, Taiwan. The main reason of land subsidence is a compression of soil, but the compression measured in the wide area is very extensive (Maryam et al., 2013; Linlin et al., 2014). Chen et al. [2010] studied the linear relationship between groundwater level and subsurface altitude variations from Global Positioning System (GPS) station in Zhuoshui River alluvial fan. But the subsurface altitude data were only from two GPS stations. Their distributions are spared and small, not enough to express the altitude variations of Zhuoshui River alluvial fan. Hung et al. [2011] used Interferometry Synthetic Aperture Radar (InSAR) to measure the surface subsidence in Zhuoshui River alluvial fan, but haven't compared with groundwater level. The study compares the correlation between rainfall events and groundwater level and compares the correlation between groundwater level and subsurface altitude, these two correlation affected by heterogeneous soil. From these relationships, a numerical model is built to simulate the land subsidence variations and estimate the coefficient of aquifer soil compressibility. Finally, the model can estimate the long-term land subsidence. Keywords: Land Subsidence, InSAR, Groundwater Level, Numerical Model, Correlation Analyses

  7. Chemical reaction networks as a model to describe UVC- and radiolytically-induced reactions of simple compounds.

    Science.gov (United States)

    Dondi, Daniele; Merli, Daniele; Albini, Angelo; Zeffiro, Alberto; Serpone, Nick

    2012-05-01

    When a chemical system is submitted to high energy sources (UV, ionizing radiation, plasma sparks, etc.), as is expected to be the case of prebiotic chemistry studies, a plethora of reactive intermediates could form. If oxygen is present in excess, carbon dioxide and water are the major products. More interesting is the case of reducing conditions where synthetic pathways are also possible. This article examines the theoretical modeling of such systems with random-generated chemical networks. Four types of random-generated chemical networks were considered that originated from a combination of two connection topologies (viz., Poisson and scale-free) with reversible and irreversible chemical reactions. The results were analyzed taking into account the number of the most abundant products required for reaching 50% of the total number of moles of compounds at equilibrium, as this may be related to an actual problem of complex mixture analysis. The model accounts for multi-component reaction systems with no a priori knowledge of reacting species and the intermediates involved if system components are sufficiently interconnected. The approach taken is relevant to an earlier study on reactions that may have occurred in prebiotic systems where only a few compounds were detected. A validation of the model was attained on the basis of results of UVC and radiolytic reactions of prebiotic mixtures of low molecular weight compounds likely present on the primeval Earth.

  8. Capitalizing on Citizen Science Data for Validating Models and Generating Hypotheses Describing Meteorological Drivers of Mosquito-Borne Disease Risk

    Science.gov (United States)

    Boger, R. A.; Low, R.; Paull, S.; Anyamba, A.; Soebiyanto, R. P.

    2017-12-01

    Temperature and precipitation are important drivers of mosquito population dynamics, and a growing set of models have been proposed to characterize these relationships. Validation of these models, and development of broader theories across mosquito species and regions could nonetheless be improved by comparing observations from a global dataset of mosquito larvae with satellite-based measurements of meteorological variables. Citizen science data can be particularly useful for two such aspects of research into the meteorological drivers of mosquito populations: i) Broad-scale validation of mosquito distribution models and ii) Generation of quantitative hypotheses regarding changes to mosquito abundance and phenology across scales. The recently released GLOBE Observer Mosquito Habitat Mapper (GO-MHM) app engages citizen scientists in identifying vector taxa, mapping breeding sites and decommissioning non-natural habitats, and provides a potentially useful new tool for validating mosquito ubiquity projections based on the analysis of remotely sensed environmental data. Our early work with GO-MHM data focuses on two objectives: validating citizen science reports of Aedes aegypti distribution through comparison with accepted scientific data sources, and exploring the relationship between extreme temperature and precipitation events and subsequent observations of mosquito larvae. Ultimately the goal is to develop testable hypotheses regarding the shape and character of this relationship between mosquito species and regions.

  9. How Mathematics Describes Life

    Science.gov (United States)

    Teklu, Abraham

    2017-01-01

    The circle of life is something we have all heard of from somewhere, but we don't usually try to calculate it. For some time we have been working on analyzing a predator-prey model to better understand how mathematics can describe life, in particular the interaction between two different species. The model we are analyzing is called the Holling-Tanner model, and it cannot be solved analytically. The Holling-Tanner model is a very common model in population dynamics because it is a simple descriptor of how predators and prey interact. The model is a system of two differential equations. The model is not specific to any particular set of species and so it can describe predator-prey species ranging from lions and zebras to white blood cells and infections. One thing all these systems have in common are critical points. A critical point is a value for both populations that keeps both populations constant. It is important because at this point the differential equations are equal to zero. For this model there are two critical points, a predator free critical point and a coexistence critical point. Most of the analysis we did is on the coexistence critical point because the predator free critical point is always unstable and frankly less interesting than the coexistence critical point. What we did is consider two regimes for the differential equations, large B and small B. B, A, and C are parameters in the differential equations that control the system where B measures how responsive the predators are to change in the population, A represents predation of the prey, and C represents the satiation point of the prey population. For the large B case we were able to approximate the system of differential equations by a single scalar equation. For the small B case we were able to predict the limit cycle. The limit cycle is a process of the predator and prey populations growing and shrinking periodically. This model has a limit cycle in the regime of small B, that we solved for

  10. Modelling of turbulent hydrocarbon combustion. Test of different reactor concepts for describing the interactions between turbulence and chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, C; Kremer, H [Ruhr-Universitaet Bochum, Lehrstuhl fuer Energieanlagentechnik, Bochum (Germany); Kilpinen, P; Hupa, M [Aabo Akademi, Turku (Finland). Combustion Chemistry Research Group

    1998-12-31

    The detailed modelling of turbulent reactive flows with CFD-codes is a major challenge in combustion science. One method of combining highly developed turbulence models and detailed chemistry in CFD-codes is the application of reactor based turbulence chemistry interaction models. In this work the influence of different reactor concepts on methane and NO{sub x} chemistry in turbulent reactive flows was investigated. Besides the classical reactor approaches, a plug flow reactor (PFR) and a perfectly stirred reactor (PSR), the Eddy-Dissipation Combustion Model (EDX) and the Eddy Dissipation Concept (EDC) were included. Based on a detailed reaction scheme and a simplified 2-step mechanism studies were performed in a simplified computational grid consisting of 5 cells. The investigations cover a temperature range from 1273 K to 1673 K and consider fuel-rich and fuel-lean gas mixtures as well as turbulent and highly turbulent flow conditions. All test cases investigated in this study showed a strong influence of the reactor residence time on the species conversion processes. Due to this characteristic strong deviations were found for the species trends resulting from the different reactor approaches. However, this influence was only concentrated on the `near burner region` and after 4-5 cells hardly any deviation and residence time dependence could be found. The importance of the residence time dependence increased when the species conversion was accelerated as it is the case for overstoichiometric combustion conditions and increased temperatures. The study focused furthermore on the fine structure in the EDC. Unlike the classical approach this part of the cell was modelled as a PFR instead of a PSR. For high temperature conditions there was hardly any difference between both reactor types. However, decreasing the temperature led to obvious deviations. Finally, the effect of the selective species transport between the cells on the conversion process was investigated

  11. Incorporating NDVI in a gravity model setting to describe spatio-temporal patterns of Lyme borreliosis incidence

    Science.gov (United States)

    Barrios, J. M.; Verstraeten, W. W.; Farifteh, J.; Maes, P.; Aerts, J. M.; Coppin, P.

    2012-04-01

    Lyme borreliosis (LB) is the most common tick-borne disease in Europe and incidence growth has been reported in several European countries during the last decade. LB is caused by the bacterium Borrelia burgdorferi and the main vector of this pathogen in Europe is the tick Ixodes ricinus. LB incidence and spatial spread is greatly dependent on environmental conditions impacting habitat, demography and trophic interactions of ticks and the wide range of organisms ticks parasite. The landscape configuration is also a major determinant of tick habitat conditions and -very important- of the fashion and intensity of human interaction with vegetated areas, i.e. human exposure to the pathogen. Hence, spatial notions as distance and adjacency between urban and vegetated environments are related to human exposure to tick bites and, thus, to risk. This work tested the adequacy of a gravity model setting to model the observed spatio-temporal pattern of LB as a function of location and size of urban and vegetated areas and the seasonal and annual change in the vegetation dynamics as expressed by MODIS NDVI. Opting for this approach implies an analogy with Newton's law of universal gravitation in which the attraction forces between two bodies are directly proportional to the bodies mass and inversely proportional to distance. Similar implementations have proven useful in fields like trade modeling, health care service planning, disease mapping among other. In our implementation, the size of human settlements and vegetated systems and the distance separating these landscape elements are considered the 'bodies'; and the 'attraction' between them is an indicator of exposure to pathogen. A novel element of this implementation is the incorporation of NDVI to account for the seasonal and annual variation in risk. The importance of incorporating this indicator of vegetation activity resides in the fact that alterations of LB incidence pattern observed the last decade have been ascribed

  12. Modelling of turbulent hydrocarbon combustion. Test of different reactor concepts for describing the interactions between turbulence and chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, C.; Kremer, H. [Ruhr-Universitaet Bochum, Lehrstuhl fuer Energieanlagentechnik, Bochum (Germany); Kilpinen, P.; Hupa, M. [Aabo Akademi, Turku (Finland). Combustion Chemistry Research Group

    1997-12-31

    The detailed modelling of turbulent reactive flows with CFD-codes is a major challenge in combustion science. One method of combining highly developed turbulence models and detailed chemistry in CFD-codes is the application of reactor based turbulence chemistry interaction models. In this work the influence of different reactor concepts on methane and NO{sub x} chemistry in turbulent reactive flows was investigated. Besides the classical reactor approaches, a plug flow reactor (PFR) and a perfectly stirred reactor (PSR), the Eddy-Dissipation Combustion Model (EDX) and the Eddy Dissipation Concept (EDC) were included. Based on a detailed reaction scheme and a simplified 2-step mechanism studies were performed in a simplified computational grid consisting of 5 cells. The investigations cover a temperature range from 1273 K to 1673 K and consider fuel-rich and fuel-lean gas mixtures as well as turbulent and highly turbulent flow conditions. All test cases investigated in this study showed a strong influence of the reactor residence time on the species conversion processes. Due to this characteristic strong deviations were found for the species trends resulting from the different reactor approaches. However, this influence was only concentrated on the `near burner region` and after 4-5 cells hardly any deviation and residence time dependence could be found. The importance of the residence time dependence increased when the species conversion was accelerated as it is the case for overstoichiometric combustion conditions and increased temperatures. The study focused furthermore on the fine structure in the EDC. Unlike the classical approach this part of the cell was modelled as a PFR instead of a PSR. For high temperature conditions there was hardly any difference between both reactor types. However, decreasing the temperature led to obvious deviations. Finally, the effect of the selective species transport between the cells on the conversion process was investigated

  13. Qualitative and numerical study of Bianchi IX Models

    International Nuclear Information System (INIS)

    Francisco, G.; Matsas, G.E.A.

    1987-01-01

    The qualitative behaviour of trajectories in the Mixmaster universe is studied. The Lyapunov exponents computed directly from the differential equations and from the Poincare map are shown to be different. A detailed discussion of the role of these exponents in analysing the effect of chaos on trajectories is presented. (Author) [pt

  14. A Monte Carlo-adjusted goodness-of-fit test for parametric models describing spatial point patterns

    KAUST Repository

    Dao, Ngocanh

    2014-04-03

    Assessing the goodness-of-fit (GOF) for intricate parametric spatial point process models is important for many application fields. When the probability density of the statistic of the GOF test is intractable, a commonly used procedure is the Monte Carlo GOF test. Additionally, if the data comprise a single dataset, a popular version of the test plugs a parameter estimate in the hypothesized parametric model to generate data for theMonte Carlo GOF test. In this case, the test is invalid because the resulting empirical level does not reach the nominal level. In this article, we propose a method consisting of nested Monte Carlo simulations which has the following advantages: the bias of the resulting empirical level of the test is eliminated, hence the empirical levels can always reach the nominal level, and information about inhomogeneity of the data can be provided.We theoretically justify our testing procedure using Taylor expansions and demonstrate that it is correctly sized through various simulation studies. In our first data application, we discover, in agreement with Illian et al., that Phlebocarya filifolia plants near Perth, Australia, can follow a homogeneous Poisson clustered process that provides insight into the propagation mechanism of these plants. In our second data application, we find, in contrast to Diggle, that a pairwise interaction model provides a good fit to the micro-anatomy data of amacrine cells designed for analyzing the developmental growth of immature retina cells in rabbits. This article has supplementary material online. © 2013 American Statistical Association, Institute of Mathematical Statistics, and Interface Foundation of North America.

  15. A simple model describing the nonlinear dynamics of the dusk/dawn asymmetry in the high-latitude thermospheric flow

    Science.gov (United States)

    Gundlach, J. P.; Larsen, M. F.; Mikkelsen, I. S.

    1988-01-01

    A simple nonlinear, axisymmetric, shallow-water numerical model has been used to study the asymmetry in the neutral flow between the dusk and dawn sides of the auroral oval. The results indicate that the Coriolis force and the curvature terms are nearly in balance on the evening side and require only a small pressure gradient to effect adjustment. The result is smaller neutral velocities near dawn and larger velocities near dusk than would be the case for a linearized treatment. A consequence is that more gravity wave energy is produced on the morning side than on the evening side.

  16. A multi-physics modelling framework to describe the behaviour of nano-scale multilayer systems undergoing irradiation damage

    International Nuclear Information System (INIS)

    Villani, Aurelien

    2015-01-01

    Radiation damage is known to lead to material failure and thus is of critical importance to lifetime and safety within nuclear reactors. While mechanical behaviour of materials under irradiation has been the subject of numerous studies, the current predictive capabilities of such phenomena appear limited. The clustering of point defects such as vacancies and self interstitial atoms gives rise to creep, void swelling and material embrittlement. Nano-scale metallic multilayer systems have be shown to have the ability to evacuate such point defects, hence delaying the occurrence of critical damage. In addition, they exhibit outstanding mechanical properties. The objective of this work is to develop a thermodynamically consistent continuum framework at the meso and nano-scales, which accounts for the major physical processes encountered in such metallic multilayer systems and is able to predict their microstructural evolution and behavior under irradiation. Mainly three physical phenomena are addressed in the present work: stress-diffusion coupling and diffusion induced creep, the void nucleation and growth in multilayer systems under irradiation, and the interaction of dislocations with the multilayer interfaces. In this framework, the microstructure is explicitly modeled, in order to account accurately for their effects on the system behavior. The diffusion creep strain rate is related to the gradient of the vacancy flux. A Cahn-Hilliard approach is used to model void nucleation and growth, and the diffusion equations for vacancies and self interstitial atoms are complemented to take into account the production of point defects due to irradiation cascades, the mutual recombination of defects and their evacuation through grain boundaries. In metallic multilayers, an interface affected zone is defined, with an additional slip plane to model the interface shearable character, and where dislocations cores are able to spread. The model is then implemented numerically

  17. PFLOTRAN User Manual: A Massively Parallel Reactive Flow and Transport Model for Describing Surface and Subsurface Processes

    Energy Technology Data Exchange (ETDEWEB)

    Lichtner, Peter C. [OFM Research, Redmond, WA (United States); Hammond, Glenn E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lu, Chuan [Idaho National Lab. (INL), Idaho Falls, ID (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bisht, Gautam [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Andre, Benjamin [National Center for Atmospheric Research, Boulder, CO (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mills, Richard [Intel Corporation, Portland, OR (United States); Univ. of Tennessee, Knoxville, TN (United States); Kumar, Jitendra [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-01-20

    PFLOTRAN solves a system of generally nonlinear partial differential equations describing multi-phase, multicomponent and multiscale reactive flow and transport in porous materials. The code is designed to run on massively parallel computing architectures as well as workstations and laptops (e.g. Hammond et al., 2011). Parallelization is achieved through domain decomposition using the PETSc (Portable Extensible Toolkit for Scientific Computation) libraries for the parallelization framework (Balay et al., 1997). PFLOTRAN has been developed from the ground up for parallel scalability and has been run on up to 218 processor cores with problem sizes up to 2 billion degrees of freedom. Written in object oriented Fortran 90, the code requires the latest compilers compatible with Fortran 2003. At the time of this writing this requires gcc 4.7.x, Intel 12.1.x and PGC compilers. As a requirement of running problems with a large number of degrees of freedom, PFLOTRAN allows reading input data that is too large to fit into memory allotted to a single processor core. The current limitation to the problem size PFLOTRAN can handle is the limitation of the HDF5 file format used for parallel IO to 32 bit integers. Noting that 232 = 4; 294; 967; 296, this gives an estimate of the maximum problem size that can be currently run with PFLOTRAN. Hopefully this limitation will be remedied in the near future.

  18. A new multiscale model to describe a modified Hall-Petch relation at different scales for nano and micro materials

    Science.gov (United States)

    Fadhil, Sadeem Abbas; Alrawi, Aoday Hashim; Azeez, Jazeel H.; Hassan, Mohsen A.

    2018-04-01

    In the present work, a multiscale model is presented and used to modify the Hall-Petch relation for different scales from nano to micro. The modified Hall-Petch relation is derived from a multiscale equation that determines the cohesive energy between the atoms and their neighboring grains. This brings with it a new term that was originally ignored even in the atomistic models. The new term makes it easy to combine all other effects to derive one modified equation for the Hall-Petch relation that works for all scales together, without the need to divide the scales into two scales, each scale with a different equation, as it is usually done in other works. Due to that, applying the new relation does not require a previous knowledge of the grain size distribution. This makes the new derived relation more consistent and easier to be applied for all scales. The new relation is used to fit the data for Copper and Nickel and it is applied well for the whole range of grain sizes from nano to micro scales.

  19. Improved rigorous upper bounds for transport due to passive advection described by simple models of bounded systems

    International Nuclear Information System (INIS)

    Kim, Chang-Bae; Krommes, J.A.

    1988-08-01

    The work of Krommes and Smith on rigorous upper bounds for the turbulent transport of a passively advected scalar [/ital Ann. Phys./ 177:246 (1987)] is extended in two directions: (1) For their ''reference model,'' improved upper bounds are obtained by utilizing more sophisticated two-time constraints which include the effects of cross-correlations up to fourth order. Numerical solutions of the model stochastic differential equation are also obtained; they show that the new bounds compare quite favorably with the exact results, even at large Reynolds and Kubo numbers. (2) The theory is extended to take account of a finite spatial autocorrelation length L/sub c/. As a reasonably generic example, the problem of particle transport due to statistically specified stochastic magnetic fields in a collisionless turbulent plasma is revisited. A bound is obtained which reduces for small L/sub c/ to the quasilinear limit and for large L/sub c/ to the strong turbulence limit, and which provides a reasonable and rigorous interpolation for intermediate values of L/sub c/. 18 refs., 6 figs

  20. Involving mental health service users in suicide-related research: a qualitative inquiry model.

    Science.gov (United States)

    Lees, David; Procter, Nicholas; Fassett, Denise; Handley, Christine

    2016-03-01

    To describe the research model developed and successfully deployed as part of a multi-method qualitative study investigating suicidal service-users' experiences of mental health nursing care. Quality mental health care is essential to limiting the occurrence and burden of suicide, however there is a lack of relevant research informing practice in this context. Research utilising first-person accounts of suicidality is of particular importance to expanding the existing evidence base. However, conducting ethical research to support this imperative is challenging. The model discussed here illustrates specific and more generally applicable principles for qualitative research regarding sensitive topics and involving potentially vulnerable service-users. Researching into mental health service users with first-person experience of suicidality requires stakeholder and institutional support, researcher competency, and participant recruitment, consent, confidentiality, support and protection. Research with service users into their experiences of sensitive issues such as suicidality can result in rich and valuable data, and may also provide positive experiences of collaboration and inclusivity. If challenges are not met, objectification and marginalisation of service-users may be reinforced, and limitations in the evidence base and service provision may be perpetuated.

  1. The Landau-Lifshitz equation describes the Ising spin correlation function in the free-fermion model

    CERN Document Server

    Rutkevich, S B

    1998-01-01

    We consider time and space dependence of the Ising spin correlation function in a continuous one-dimensional free-fermion model. By the Ising spin we imply the 'sign' variable, which takes alternating +-1 values in adjacent domains bounded by domain walls (fermionic world paths). The two-point correlation function is expressed in terms of the solution of the Cauchy problem for a nonlinear partial differential equation, which is proved to be equivalent to the exactly solvable Landau-Lifshitz equation. A new zero-curvature representation for this equation is presented. In turn, the initial condition for the Cauchy problem is given by the solution of a nonlinear ordinary differential equation, which has also been derived. In the Ising limit the above-mentioned partial and ordinary differential equations reduce to the sine-Gordon and Painleve III equations, respectively. (author)

  2. Model calculations of doubly closed shell nuclei in the integral-differential equation approach describing the two body correlations

    International Nuclear Information System (INIS)

    Brizzi, R.; Fabre de la Ripelle, M.; Lassaut, M.

    1999-01-01

    The binding energies and root mean square radii obtained from the Integro-Differential Equation Approach (IDEA) and from the Weight Function Approximation (WFA) of the IDEA for an even number of bosons and for 12 C, 16 O and 40 Ca are compared to those recently obtained by the Variational Monte Carlo, Fermi Hypernetted Chain and Coupled Cluster expansion method with model potentials. The IDEA provides numbers very similar to those obtained by other methods although it takes only two-body correlations into account. The analytical expression of the wave function for the WFA is given for bosons in ground state when the interaction pair is outside the potential range. Due to its simple structure, the equations of the IDEA can easily be extended to realistic interaction for nuclei like it has already been done for the tri-nucleon and the 4 He. (authors)

  3. Learned helplessness or expectancy-value? A psychological model for describing the experiences of different categories of unemployed people.

    Science.gov (United States)

    García Rodríguez, Y

    1997-06-01

    Various studies have explored the relationships between unemployment and expectation of success, commitment to work, motivation, causal attributions, self-esteem and depression. A model is proposed that assumes the relationships between these variables are moderated by (a) whether or not the unemployed individual is seeking a first job and (b) age. It is proposed that for the unemployed who are seeking their first job (seekers) the relationships among these variables will be consistent with expectancy-value theory, but for those who have had a previous job (losers), the relationships will be more consistent with learned helplessness theory. It is further assumed that within this latter group the young losers will experience "universal helplessness" whereas the adult losers will experience "personal helplessness".

  4. Development of a model to describe organic films on aerosol particles and cloud droplets. Final report; Entwicklung eines Modells zur Beschreibung organischer Filme auf Aerosolteilchen und Wolkentropfen. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Forkel, R. (ed.); Seidl, W.

    2000-12-01

    Organic substances with polar groups are enriched on water surfaces and can form monomolecular surface films which can reduce the surface tension. A new model to describe surface films is presented, which describes in detail the film forming properties of fatty acids with up to 22 carbon atoms. The model is applied to measured concentrations of fatty acids (from the literature) in rain water and on aerosol particles and cloud droplets. An investigation of the sources of fatty acids has shown, that abrasion of the wax layer on leaves and needles is the main sources for surface film material in the western USA. Anthropogenic sources in urban areas are meat preparation and cigarette smoke. The agreement between model results and measurements when the model was applied to rain water confirms the original assumption that fatty acids are a main compound of surface films in rain water. For humid aerosol particles the application of the model on measured concentrations of fatty acids only showed strongly diluted films. Only for remote forest areas in western USA concentrated films were found, with the surface tension reduced by 20 to 30%. On cloud droplets the surface films is still more diluted than on aerosol particles. For all investigated cases the films was too much diluted to have an effect on the activation process of cloud droplets. (orig.) [German] Organische Substanzen mit polaren Gruppen reichern sich an der Wasseroberflaeche an und koennen monomolekulare Oberflaechenfilme bilden, die zu einer Verringerung der Oberflaechenspannung fuehren. Es wird ein neues Modell zur Beschreibung eines Oberflaechenfilms beschrieben, das detailliert die filmbildenden Eigenschaften der Fettsaeuren mit bis zu 22 Kohlenstoffatomen erfasst. Dieses Modell ist auf gemessene Konzentrationen von Fettsaeuren (Literaturdaten) in Regenwasser und auf atmosphaerischen Aerosolteilchen und Wolkentropfen angewandt worden. Eine Betrachtung der Quellen der Fettsaeuren zeigte, dass der Abrieb der

  5. Chaotic-Dynamical Conceptual Model to Describe Fluid Flow and Contaminant Transport in a Fractured Vadose Zone

    International Nuclear Information System (INIS)

    Faybishenko, Boris; Doughty, Christine; Geller, Jil T.

    1999-01-01

    DOE faces the remediation of numerous contaminated sites, such as those at Hanford, INEEL, LLNL, and LBNL, where organic and/or radioactive wastes were intentionally or accidentally released to the vadose zone from surface spills, underground tanks, cribs, shallow ponds, and deep wells. Migration of these contaminants through the vadose zone has led to the contamination of (or threatens to contaminate) underlying groundwater. A key issue in choosing a corrective action plan to clean up contaminated sites is the determination of the location, total mass, mobility and travel time to receptors for contaminants moving in the vadose zone. These problems are difficult to solve in a technically defensible and accurate manner because contaminants travel downward intermittently, through narrow pathways, driven by variations in environmental conditions. These preferential flow pathways can be difficult to find and predict. The primary objective of this project is to determine if and when dynamical chaos theory can be used to investigate infiltration of fluid and contaminant transport in heterogeneous soils and fractured rocks. The objective of this project is being achieved through the following activities: Development of multi scale conceptual models and mathematical and numerical algorithms for flow and transport, which incorporate both (a) the spatial variability of heterogeneous porous and fractured media and (b) the temporal dynamics of flow and transport; Development of appropriate experimental field and laboratory techniques needed to detect diagnostic parameters for chaotic behavior of flow; Evaluation of chaotic behavior of flow in laboratory and field experiments using methods from non-linear dynamics; Evaluation of the impact these dynamics may have on contaminant transport through heterogeneous fractured rocks and soils and remediation efforts. This approach is based on the consideration of multi scale spatial heterogeneity and flow phenomena that are affected by

  6. A plant wide aqueous phase chemistry model describing pH variations and ion speciation/pairing in wastewater treatment process models

    DEFF Research Database (Denmark)

    Flores-Alsina, X.; Mbamba, C. Kazadi; Solon, K.

    cationic/anionic loads. In this way, the general applicability/flexibility of the proposed approach is demonstrated by implementing the aqueous phase chemistry module in some of the most frequently used WWTP process simulation models. Finally, it is shown how traditional wastewater modelling studies can......, require a major, but unavoidable, additional degree of complexity when representing cationic/anionic behaviour in Activated Sludge (AS)/Anaerobic Digestion (AD) systems (Ikumi et al., 2014). In this paper, a plant-wide aqueous phase chemistry module describing pH variations plus ion speciation...... of Ordinary Differential Equations (ODEs) in order to reduce the overall stiffness of the system, thereby enhancing simulation speed. Additionally, a multi-dimensional version of the Newton-Raphson algorithm is applied to handle the existing multiple algebraic inter-dependencies (Solon et al., 2015...

  7. Integrated decision-making about housing, energy and wellbeing: a qualitative system dynamics model.

    Science.gov (United States)

    Macmillan, Alexandra; Davies, Michael; Shrubsole, Clive; Luxford, Naomi; May, Neil; Chiu, Lai Fong; Trutnevyte, Evelina; Bobrova, Yekatherina; Chalabi, Zaid

    2016-03-08

    The UK government has an ambitious goal to reduce carbon emissions from the housing stock through energy efficiency improvements. This single policy goal is a strong driver for change in the housing system, but comes with positive and negative "unintended consequences" across a broad range of outcomes for health, equity and environmental sustainability. The resulting policies are also already experiencing under-performance through a failure to consider housing as a complex system. This research aimed to move from considering disparate objectives of housing policies in isolation to mapping the links between environmental, economic, social and health outcomes as a complex system. We aimed to support a broad range of housing policy stakeholders to improve their understanding of housing as a complex system through a collaborative learning process. We used participatory system dynamics modelling to develop a qualitative causal theory linking housing, energy and wellbeing. Qualitative interviews were followed by two interactive workshops to develop the model, involving representatives from national and local government, housing industries, non-government organisations, communities and academia. More than 50 stakeholders from 37 organisations participated. The process resulted in a shared understanding of wellbeing as it relates to housing; an agreed set of criteria against which to assess to future policy options; and a comprehensive set of causal loop diagrams describing the housing, energy and wellbeing system. The causal loop diagrams cover seven interconnected themes: community connection and quality of neighbourhoods; energy efficiency and climate change; fuel poverty and indoor temperature; household crowding; housing affordability; land ownership, value and development patterns; and ventilation and indoor air pollution. The collaborative learning process and the model have been useful for shifting the thinking of a wide range of housing stakeholders towards a more

  8. A conceptual framework to model long-run qualitative change in the energy system

    OpenAIRE

    Ebersberger, Bernd

    2004-01-01

    A conceptual framework to model long-run qualitative change in the energy system / A. Pyka, B. Ebersberger, H. Hanusch. - In: Evolution and economic complexity / ed. J. Stanley Metcalfe ... - Cheltenham [u.a.] : Elgar, 2004. - S. 191-213

  9. An Integrated Qualitative and Quantitative Biochemical Model Learning Framework Using Evolutionary Strategy and Simulated Annealing.

    Science.gov (United States)

    Wu, Zujian; Pang, Wei; Coghill, George M

    2015-01-01

    Both qualitative and quantitative model learning frameworks for biochemical systems have been studied in computational systems biology. In this research, after introducing two forms of pre-defined component patterns to represent biochemical models, we propose an integrative qualitative and quantitative modelling framework for inferring biochemical systems. In the proposed framework, interactions between reactants in the candidate models for a target biochemical system are evolved and eventually identified by the application of a qualitative model learning approach with an evolution strategy. Kinetic rates of the models generated from qualitative model learning are then further optimised by employing a quantitative approach with simulated annealing. Experimental results indicate that our proposed integrative framework is feasible to learn the relationships between biochemical reactants qualitatively and to make the model replicate the behaviours of the target system by optimising the kinetic rates quantitatively. Moreover, potential reactants of a target biochemical system can be discovered by hypothesising complex reactants in the synthetic models. Based on the biochemical models learned from the proposed framework, biologists can further perform experimental study in wet laboratory. In this way, natural biochemical systems can be better understood.

  10. ADMIT: a toolbox for guaranteed model invalidation, estimation and qualitative-quantitative modeling.

    Science.gov (United States)

    Streif, Stefan; Savchenko, Anton; Rumschinski, Philipp; Borchers, Steffen; Findeisen, Rolf

    2012-05-01

    Often competing hypotheses for biochemical networks exist in the form of different mathematical models with unknown parameters. Considering available experimental data, it is then desired to reject model hypotheses that are inconsistent with the data, or to estimate the unknown parameters. However, these tasks are complicated because experimental data are typically sparse, uncertain, and are frequently only available in form of qualitative if-then observations. ADMIT (Analysis, Design and Model Invalidation Toolbox) is a MatLab(TM)-based tool for guaranteed model invalidation, state and parameter estimation. The toolbox allows the integration of quantitative measurement data, a priori knowledge of parameters and states, and qualitative information on the dynamic or steady-state behavior. A constraint satisfaction problem is automatically generated and algorithms are implemented for solving the desired estimation, invalidation or analysis tasks. The implemented methods built on convex relaxation and optimization and therefore provide guaranteed estimation results and certificates for invalidity. ADMIT, tutorials and illustrative examples are available free of charge for non-commercial use at http://ifatwww.et.uni-magdeburg.de/syst/ADMIT/

  11. CONFIG - Adapting qualitative modeling and discrete event simulation for design of fault management systems

    Science.gov (United States)

    Malin, Jane T.; Basham, Bryan D.

    1989-01-01

    CONFIG is a modeling and simulation tool prototype for analyzing the normal and faulty qualitative behaviors of engineered systems. Qualitative modeling and discrete-event simulation have been adapted and integrated, to support early development, during system design, of software and procedures for management of failures, especially in diagnostic expert systems. Qualitative component models are defined in terms of normal and faulty modes and processes, which are defined by invocation statements and effect statements with time delays. System models are constructed graphically by using instances of components and relations from object-oriented hierarchical model libraries. Extension and reuse of CONFIG models and analysis capabilities in hybrid rule- and model-based expert fault-management support systems are discussed.

  12. Incorporation of FcRn-mediated disposition model to describe the population pharmacokinetics of therapeutic monoclonal IgG antibody in clinical patients.

    Science.gov (United States)

    Ng, Chee M

    2016-03-01

    The two-compartment linear model used to describe the population pharmacokinetics (PK) of many therapeutic monoclonal antibodies (TMAbs) offered little biological insight to antibody disposition in humans. The purpose of this study is to develop a semi-mechanistic FcRn-mediated IgG disposition model to describe the population PK of TMAbs in clinical patients. A standard two-compartment linear PK model from a previously published population PK model of pertuzumab was used to simulate intensive PK data of 100 subjects for model development. Two different semi-mechanistic FcRn-mediated IgG disposition models were developed and First Order Conditional Estimation (FOCE) with the interaction method in NONMEM was used to obtain the final model estimates. The performances of these models were then compared with the two-compartment linear PK model used to simulate the data for model development. A semi-mechanistic FcRn-mediated IgG disposition model consisting of a peripheral tissue compartment and FcRn-containing endosomes in the central compartment best describes the simulated pertuzumab population PK data. This developed semi-mechanistic population PK model had the same number of model parameters, produced very similar concentration-time profiles but provided additional biological insight to the FcRn-mediated IgG disposition in human subjects compared with the standard linear two-compartment linear PK model. This first reported semi-mechanistic model may serve as an important model framework for developing future population PK models of TMAbs in clinical patients. Copyright © 2015 John Wiley & Sons, Ltd.

  13. Comparison of different two-pathway models for describing the combined effect of DO and nitrite on the nitrous oxide production by ammonia-oxidizing bacteria.

    Science.gov (United States)

    Lang, Longqi; Pocquet, Mathieu; Ni, Bing-Jie; Yuan, Zhiguo; Spérandio, Mathieu

    2017-02-01

    The aim of this work is to compare the capability of two recently proposed two-pathway models for predicting nitrous oxide (N 2 O) production by ammonia-oxidizing bacteria (AOB) for varying ranges of dissolved oxygen (DO) and nitrite. The first model includes the electron carriers whereas the second model is based on direct coupling of electron donors and acceptors. Simulations are confronted to extensive sets of experiments (43 batches) from different studies with three different microbial systems. Despite their different mathematical structures, both models could well and similarly describe the combined effect of DO and nitrite on N 2 O production rate and emission factor. The model-predicted contributions for nitrifier denitrification pathway and hydroxylamine pathway also matched well with the available isotopic measurements. Based on sensitivity analysis, calibration procedures are described and discussed for facilitating the future use of those models.

  14. Evaluating quantitative and qualitative models: An application for nationwide water erosion assessment in Ethiopia

    NARCIS (Netherlands)

    Sonneveld, B.G.J.S.; Keyzer, M.A.; Stroosnijder, L

    2011-01-01

    This paper tests the candidacy of one qualitative response model and two quantitative models for a nationwide water erosion hazard assessment in Ethiopia. After a descriptive comparison of model characteristics the study conducts a statistical comparison to evaluate the explanatory power of the

  15. Evaluating quantitative and qualitative models: an application for nationwide water erosion assessment in Ethiopia

    NARCIS (Netherlands)

    Sonneveld, B.G.J.S.; Keyzer, M.A.; Stroosnijder, L.

    2011-01-01

    This paper tests the candidacy of one qualitative response model and two quantitative models for a nationwide water erosion hazard assessment in Ethiopia. After a descriptive comparison of model characteristics the study conducts a statistical comparison to evaluate the explanatory power of the

  16. Discriminating Between Models of Ambiguity Attitude : A Qualitative Test

    NARCIS (Netherlands)

    Cubitt, Robin; van de Kuilen, Gijs; Mukerji, Sujoy

    The exchange between Epstein (2010) and Klibanoff et al. (2012) identified a behavioral issue that sharply distinguishes between two classes of models of ambiguity sensitivity, exemplified by the 훼- MEU model and the smooth ambiguity model, respectively. The issue in question is whether a subject’s

  17. A qualitatively validated mathematical-computational model of the immune response to the yellow fever vaccine.

    Science.gov (United States)

    Bonin, Carla R B; Fernandes, Guilherme C; Dos Santos, Rodrigo W; Lobosco, Marcelo

    2018-05-25

    Although a safe and effective yellow fever vaccine was developed more than 80 years ago, several issues regarding its use remain unclear. For example, what is the minimum dose that can provide immunity against the disease? A useful tool that can help researchers answer this and other related questions is a computational simulator that implements a mathematical model describing the human immune response to vaccination against yellow fever. This work uses a system of ten ordinary differential equations to represent a few important populations in the response process generated by the body after vaccination. The main populations include viruses, APCs, CD8+ T cells, short-lived and long-lived plasma cells, B cells and antibodies. In order to qualitatively validate our model, four experiments were carried out, and their computational results were compared to experimental data obtained from the literature. The four experiments were: a) simulation of a scenario in which an individual was vaccinated against yellow fever for the first time; b) simulation of a booster dose ten years after the first dose; c) simulation of the immune response to the yellow fever vaccine in individuals with different levels of naïve CD8+ T cells; and d) simulation of the immune response to distinct doses of the yellow fever vaccine. This work shows that the simulator was able to qualitatively reproduce some of the experimental results reported in the literature, such as the amount of antibodies and viremia throughout time, as well as to reproduce other behaviors of the immune response reported in the literature, such as those that occur after a booster dose of the vaccine.

  18. A model framework to describe growth-linked biodegradation of trace-level pesticides in the presence of coincidental carbon substrates and microbes

    DEFF Research Database (Denmark)

    Liu, Li; Helbling, Damian E.; Kohler, Hans-Peter E.

    2014-01-01

    described were: the growth-linked biodegradation of micropollutant at environmentally relevant concentrations; the effect of coincidental assimilable organic carbon substrates; and the effect of coincidental microbes that compete for assimilable organic carbon substrates. We used Monod kinetic models...... to describe substrate utilization and microbial growth rates for specific pesticide and degrader pairs. We then extended the model to include terms for utilization of assimilable organic carbon substrates by the specific degrader and coincidental microbes, growth on assimilable organic carbon substrates......, challenges remain in developing engineered remediation strategies for pesticide-contaminated environments because the fundamental processes that regulate growth-linked biodegradation of pesticides in natural environments remain poorly understood. In this research, we developed a model framework to describe...

  19. Qualitative mathematics for the social sciences mathematical models for research on cultural dynamics

    CERN Document Server

    Rudolph, Lee

    2012-01-01

    In this book Lee Rudolph brings together international contributors who combine psychological and mathematical perspectives to analyse how qualitative mathematics can be used to create models of social and psychological processes. Bridging the gap between the fields with an imaginative and stimulating collection of contributed chapters, the volume updates the current research on the subject, which until now has been rather limited, focussing largely on the use of statistics. Qualitative Mathematics for the Social Sciences contains a variety of useful illustrative figures, in

  20. Religious views of the 'medical' rehabilitation model: a pilot qualitative study.

    Science.gov (United States)

    Yamey, Gavin; Greenwood, Richard

    2004-04-22

    To explore the religious beliefs that patients may bring to the rehabilitation process, and the hypothesis that these beliefs may diverge from the medical model of rehabilitation. Qualitative semi-structured interviews with representatives of six major religions--Islam, Buddhism, Christianity, Judaism, Sikhism, and Hinduism. Representatives were either health care professionals or religious leaders, all with an interest in how their religion approached health issues. There were three recurrent themes in the interviews: religious explanations for injury and illness; beliefs about recovery; religious duties of care towards family members. The Buddhist, Sikh, and Hindu interviewees described beliefs about karma--unfortunate events happening due to a person's former deeds. Fatalistic ideas, involving God having control over an individual's recovery, were expressed by the Muslim, Jewish, and Christian interviewees. All interviewees expressed the fundamental importance of a family's religious duty of care towards ill or injured relatives, and all expressed some views that were compatible with the medical model of rehabilitation. Religious beliefs may both diverge from and resonate with the medical rehabilitation model. Understanding these beliefs may be valuable in facilitating the rehabilitation of diverse religious groups.

  1. Health literacy and the social determinants of health: a qualitative model from adult learners.

    Science.gov (United States)

    Rowlands, Gillian; Shaw, Adrienne; Jaswal, Sabrena; Smith, Sian; Harpham, Trudy

    2017-02-01

    Health literacy, ‘the personal characteristics and social resources needed for individuals and communities to access, understand, appraise and use information and services to make decisions about health’, is key to improving peoples’ control over modifiable social determinants of health (SDH). This study listened to adult learners to understand their perspectives on gathering, understanding and using information for health. This qualitative project recruited participants from community skills courses to identify relevant ‘health information’ factors. Subsequently different learners put these together to develop a model of their ‘Journey to health’. Twenty-seven participants were recruited; twenty from community health literacy courses and seven from an adult basic literacy and numeracy course. Participants described health as a ‘journey’ starting from an individual's family, ethnicity and culture. Basic (functional) health literacy skills were needed to gather and understand information. More complex interactive health literacy skills were needed to evaluate the importance and relevance of information in context, and make health decisions. Critical health literacy skills could be used to adapt negative external factors that might inhibit health-promotion. Our model is an iterative linear one moving from ethnicity, community and culture, through lifestyle, to health, with learning revisited in the context of different sources of support. It builds on existing models by highlighting the importance of SDH in the translation of new health knowledge into healthy behaviours, and the importance of health literacy in enabling people to overcome barriers to health.

  2. A Conceptual Model of Irritability Following Traumatic Brain Injury: A Qualitative, Participatory Research Study.

    Science.gov (United States)

    Hammond, Flora M; Davis, Christine; Cook, James R; Philbrick, Peggy; Hirsch, Mark A

    2016-01-01

    Individuals with a history of traumatic brain injury (TBI) may have chronic problems with irritability, which can negatively affect their lives. (1) To describe the experience (thoughts and feelings) of irritability from the perspectives of multiple people living with or affected by the problem, and (2) to develop a conceptual model of irritability. Qualitative, participatory research. Forty-four stakeholders (individuals with a history of TBI, family members, community professionals, healthcare providers, and researchers) divided into 5 focus groups. Each group met 10 times to discuss the experience of irritability following TBI. Data were coded using grounded theory to develop themes, metacodes, and theories. Not applicable. A conceptual model emerged in which irritability has 5 dimensions: affective (related to moods and feelings); behavioral (especially in areas of self-regulation, impulse control, and time management); cognitive-perceptual (self-talk and ways of seeing the world); relational issues (interpersonal and family dynamics); and environmental (including environmental stimuli, change, disruptions in routine, and cultural expectations). This multidimensional model provides a framework for assessment, treatment, and future research aimed at better understanding irritability, as well as the development of assessment tools and treatment interventions.

  3. [Analysis of the stability and adaptability of near infrared spectra qualitative analysis model].

    Science.gov (United States)

    Cao, Wu; Li, Wei-jun; Wang, Ping; Zhang, Li-ping

    2014-06-01

    The stability and adaptability of model of near infrared spectra qualitative analysis were studied. Method of separate modeling can significantly improve the stability and adaptability of model; but its ability of improving adaptability of model is limited. Method of joint modeling can not only improve the adaptability of the model, but also the stability of model, at the same time, compared to separate modeling, the method can shorten the modeling time, reduce the modeling workload; extend the term of validity of model, and improve the modeling efficiency. The experiment of model adaptability shows that, the correct recognition rate of separate modeling method is relatively low, which can not meet the requirements of application, and joint modeling method can reach the correct recognition rate of 90%, and significantly enhances the recognition effect. The experiment of model stability shows that, the identification results of model by joint modeling are better than the model by separate modeling, and has good application value.

  4. Structuring Qualitative Data for Agent-Based Modelling

    NARCIS (Netherlands)

    Ghorbani, Amineh; Dijkema, Gerard P.J.; Schrauwen, Noortje

    2015-01-01

    Using ethnography to build agent-based models may result in more empirically grounded simulations. Our study on innovation practice and culture in the Westland horticulture sector served to explore what information and data from ethnographic analysis could be used in models and how. MAIA, a

  5. Qualitative dynamical analysis of chaotic plasma perturbations model

    Science.gov (United States)

    Elsadany, A. A.; Elsonbaty, Amr; Agiza, H. N.

    2018-06-01

    In this work, an analytical framework to understand nonlinear dynamics of plasma perturbations model is introduced. In particular, we analyze the model presented by Constantinescu et al. [20] which consists of three coupled ODEs and contains three parameters. The basic dynamical properties of the system are first investigated by the ways of bifurcation diagrams, phase portraits and Lyapunov exponents. Then, the normal form technique and perturbation methods are applied so as to the different types of bifurcations that exist in the model are investigated. It is proved that pitcfork, Bogdanov-Takens, Andronov-Hopf bifurcations, degenerate Hopf and homoclinic bifurcation can occur in phase space of the model. Also, the model can exhibit quasiperiodicity and chaotic behavior. Numerical simulations confirm our theoretical analytical results.

  6. Co-Designing and Co-Teaching Graduate Qualitative Methods: An Innovative Ethnographic Workshop Model

    Science.gov (United States)

    Cordner, Alissa; Klein, Peter T.; Baiocchi, Gianpaolo

    2012-01-01

    This article describes an innovative collaboration between graduate students and a faculty member to co-design and co-teach a graduate-level workshop-style qualitative methods course. The goal of co-designing and co-teaching the course was to involve advanced graduate students in all aspects of designing a syllabus and leading class discussions in…

  7. Learning to Act: Qualitative Learning of Deterministic Action Models

    DEFF Research Database (Denmark)

    Bolander, Thomas; Gierasimczuk, Nina

    2017-01-01

    In this article we study learnability of fully observable, universally applicable action models of dynamic epistemic logic. We introduce a framework for actions seen as sets of transitions between propositional states and we relate them to their dynamic epistemic logic representations as action...... in the limit (inconclusive convergence to the right action model). We show that deterministic actions are finitely identifiable, while arbitrary (non-deterministic) actions require more learning power—they are identifiable in the limit. We then move on to a particular learning method, i.e. learning via update......, which proceeds via restriction of a space of events within a learning-specific action model. We show how this method can be adapted to learn conditional and unconditional deterministic action models. We propose update learning mechanisms for the afore mentioned classes of actions and analyse...

  8. Representing and managing uncertainty in qualitative ecological models

    NARCIS (Netherlands)

    Nuttle, T.; Bredeweg, B.; Salles, P.; Neumann, M.

    2009-01-01

    Ecologists and decision makers need ways to understand systems, test ideas, and make predictions and explanations about systems. However, uncertainty about causes and effects of processes and parameter values is pervasive in models of ecological systems. Uncertainty associated with incomplete

  9. A qualitative model of the salmon life cycle in the context of river rehabilitation

    NARCIS (Netherlands)

    Noble, R.A.A.; Bredeweg, B.; Linnebank, F.; Salles, P.; Cowx, I.G.; Žabkar, J.; Bratko, I.

    2009-01-01

    A qualitative model was developed in Garp3 to capture and formalise knowledge about river rehabilitation and the management of an Atlantic salmon population. The model integrates information about the ecology of the salmon life cycle, the environmental factors that may limit the survival of key life

  10. A Proposed Model of Retransformed Qualitative Data within a Mixed Methods Research Design

    Science.gov (United States)

    Palladino, John M.

    2009-01-01

    Most models of mixed methods research design provide equal emphasis of qualitative and quantitative data analyses and interpretation. Other models stress one method more than the other. The present article is a discourse about the investigator's decision to employ a mixed method design to examine special education teachers' advocacy and…

  11. The spruce budworm and forest: a qualitative comparison of ODE and Boolean models

    Directory of Open Access Journals (Sweden)

    Raina Robeva

    2016-01-01

    Full Text Available Boolean and polynomial models of biological systems have emerged recently as viable companions to differential equations models. It is not immediately clear however whether such models are capable of capturing the multi-stable behaviour of certain biological systems: this behaviour is often sensitive to changes in the values of the model parameters, while Boolean and polynomial models are qualitative in nature. In the past few years, Boolean models of gene regulatory systems have been shown to capture multi-stability at the molecular level, confirming that such models can be used to obtain information about the system’s qualitative dynamics when precise information regarding its parameters may not be available. In this paper, we examine Boolean approximations of a classical ODE model of budworm outbreaks in a forest and show that these models exhibit a qualitative behaviour consistent with that derived from the ODE models. In particular, we demonstrate that these models can capture the bistable nature of insect population outbreaks, thus showing that Boolean models can be successfully utilized beyond the molecular level.

  12. Application of the dosimetric model described by Humm to target 131I monoclonal antibodies to leukaemic cells in the cerebrospinal fluid

    International Nuclear Information System (INIS)

    Papanastassiou, V.; Pizer, B.L.; Kemshead, J.T.

    1993-01-01

    In 1986 Humm suggested a dosimetric model for targeted radiation therapy that considered both the physical characteristics of the radionuclide used and the morphology of the targeted tumour. Using this model he described the dose advantage due to antibody binding in terms of a ratio of tumour radiation dose to that of normal tissue. The model applied to non-solid tumours assumes no cell clumping and hence no cross-fire effect. The authors demonstrate the direct application of the model to a particular clinical scenario; the targeting of 131 I monoclonal antibodies to leukaemic cells within the cerebrospinal fluid (CSF). In this situation the dose advantage is much higher than the figure reported by Humm, which was arrived at by considering a more general application of the model. (author)

  13. Unicriterion Model: A Qualitative Decision Making Method That Promotes Ethics

    Directory of Open Access Journals (Sweden)

    Fernando Guilherme Silvano Lobo Pimentel

    2011-06-01

    Full Text Available Management decision making methods frequently adopt quantitativemodels of several criteria that bypass the question of whysome criteria are considered more important than others, whichmakes more difficult the task of delivering a transparent viewof preference structure priorities that might promote ethics andlearning and serve as a basis for future decisions. To tackle thisparticular shortcoming of usual methods, an alternative qualitativemethodology of aggregating preferences based on the rankingof criteria is proposed. Such an approach delivers a simpleand transparent model for the solution of each preference conflictfaced during the management decision making process. Themethod proceeds by breaking the decision problem into ‘two criteria– two alternatives’ scenarios, and translating the problem ofchoice between alternatives to a problem of choice between criteriawhenever appropriate. The unicriterion model method is illustratedby its application in a car purchase and a house purchasedecision problem.

  14. ARCHITECTURES AND ALGORITHMS FOR COGNITIVE NETWORKS ENABLED BY QUALITATIVE MODELS

    DEFF Research Database (Denmark)

    Balamuralidhar, P.

    2013-01-01

    traditional limitations and potentially achieving better performance. The vision is that, networks should be able to monitor themselves, reason upon changes in self and environment, act towards the achievement of specific goals and learn from experience. The concept of a Cognitive Engine (CE) supporting...... cognitive functions, as part of network elements, enabling above said autonomic capabilities is gathering attention. Awareness of the self and the world is an important aspect of the cognitive engine to be autonomic. This is achieved through embedding their models in the engine, but the complexity...... of the cognitive engine that incorporates a context space based information structure to its knowledge model. I propose a set of guiding principles behind a cognitive system to be autonomic and use them with additional requirements to build a detailed architecture for the cognitive engine. I define a context space...

  15. Describing chaotic attractors: Regular and perpetual points

    Science.gov (United States)

    Dudkowski, Dawid; Prasad, Awadhesh; Kapitaniak, Tomasz

    2018-03-01

    We study the concepts of regular and perpetual points for describing the behavior of chaotic attractors in dynamical systems. The idea of these points, which have been recently introduced to theoretical investigations, is thoroughly discussed and extended into new types of models. We analyze the correlation between regular and perpetual points, as well as their relation with phase space, showing the potential usefulness of both types of points in the qualitative description of co-existing states. The ability of perpetual points in finding attractors is indicated, along with its potential cause. The location of chaotic trajectories and sets of considered points is investigated and the study on the stability of systems is shown. The statistical analysis of the observing desired states is performed. We focus on various types of dynamical systems, i.e., chaotic flows with self-excited and hidden attractors, forced mechanical models, and semiconductor superlattices, exhibiting the universality of appearance of the observed patterns and relations.

  16. LINEAR MIXED MODEL TO DESCRIBE THE BASAL AREA INCREMENT FOR INDIVUDUAL CEDRO (Cedrela odorata L.TREES IN OCCIDENTAL AMAZON, BRAZIL

    Directory of Open Access Journals (Sweden)

    Thiago Augusto da Cunha

    2013-01-01

    Full Text Available Reliable growth data from trees are important to establish a rational forest management. Characteristics from trees, like the size, crown architecture and competition indices have been used to mathematically describe the increment efficiently when associated with them. However, the precise role of these effects in the growth-modeling destined to tropical trees needs to be further studied. Here it is reconstructed the basal area increment (BAI of individual Cedrela odorata trees, sampled at Amazon forest, to develop a growth- model using potential-predictors like: (1 classical tree size; (2 morphometric data; (3 competition and (4 social position including liana loads. Despite the large variation in tree size and growth, we observed that these kinds of predictor variables described well the BAI in level of individual tree. The fitted mixed model achieve a high efficiency (R2=92.7 % and predicted 3-years BAI over bark for trees of Cedrela odorata ranging from 10 to 110 cm at diameter at breast height. Tree height, steam slenderness and crown formal demonstrated high influence in the BAI growth model and explaining most of the growth variance (Partial R2=87.2%. Competition variables had negative influence on the BAI, however, explained about 7% of the total variation. The introduction of a random parameter on the regressions model (mixed modelprocedure has demonstrated a better significance approach to the data observed and showed more realistic predictions than the fixed model.

  17. A model framework to describe growth-linked biodegradation of trace-level pollutants in the presence of coincidental carbon substrates and microbes.

    Science.gov (United States)

    Liu, Li; Helbling, Damian E; Kohler, Hans-Peter E; Smets, Barth F

    2014-11-18

    Pollutants such as pesticides and their degradation products occur ubiquitously in natural aquatic environments at trace concentrations (μg L(-1) and lower). Microbial biodegradation processes have long been known to contribute to the attenuation of pesticides in contaminated environments. However, challenges remain in developing engineered remediation strategies for pesticide-contaminated environments because the fundamental processes that regulate growth-linked biodegradation of pesticides in natural environments remain poorly understood. In this research, we developed a model framework to describe growth-linked biodegradation of pesticides at trace concentrations. We used experimental data reported in the literature or novel simulations to explore three fundamental kinetic processes in isolation. We then combine these kinetic processes into a unified model framework. The three kinetic processes described were: the growth-linked biodegradation of micropollutant at environmentally relevant concentrations; the effect of coincidental assimilable organic carbon substrates; and the effect of coincidental microbes that compete for assimilable organic carbon substrates. We used Monod kinetic models to describe substrate utilization and microbial growth rates for specific pesticide and degrader pairs. We then extended the model to include terms for utilization of assimilable organic carbon substrates by the specific degrader and coincidental microbes, growth on assimilable organic carbon substrates by the specific degrader and coincidental microbes, and endogenous metabolism. The proposed model framework enables interpretation and description of a range of experimental observations on micropollutant biodegradation. The model provides a useful tool to identify environmental conditions with respect to the occurrence of assimilable organic carbon and coincidental microbes that may result in enhanced or reduced micropollutant biodegradation.

  18. The European Distribution of Sus Scrofa. Model Outputs from the Project Described within the Poster – Where are All the Boars? An Attempt to Gain a Continental Perspective

    Directory of Open Access Journals (Sweden)

    Neil Stewart Alexander

    2016-01-01

    Full Text Available Wild boar is a host of a number of arthropod-vectored diseases and its numbers are on the rise in mainland Europe. The species potentially impacts ecosystems, humans and farming practices and so its distribution is of interest to policy makers in a number of fields beyond that of the primarily epidemiological goal of this study. Three statistical model outputs describing the distribution and abundance of the species Sus scrofa (Wild boar are included in this data package. The extent of this dataset covers continental Europe. These data were presented as a poster [1] at the conference Genes, Ecosystems and Risk of Infection (GERI 2015. The first of the three models provide a European map presenting the probability of presence of Sus scrofa, which can be used to describe the likely geographical distribution of the species. The second and third models provide indices to help describe the likely abundance across the continent. The two indices include “the proportion of suitable habitat where presence is estimated” and a simple classification of boar abundance across Europe using quantiles of existing abundance data and proxies.

  19. A Qualitative Application of the Belsky Model to Explore Early Care and Education Teachers' Mealtime History, Beliefs, and Interactions.

    Science.gov (United States)

    Swindle, Taren M; Patterson, Zachary; Boden, Carrie J

    Studies on factors associated with nutrition practices in early care and education settings often focus on sociodemographic and programmatic characteristics. This qualitative study adapted and applied Belsky's determinants of parenting model to inform a broader exploration of Early Care and Education Teachers (ECETs) practices. Qualitative cross-sectional study with ECETs. The researchers interviewed ECETs in their communities across a Southern state. Purposive sampling was employed to recruit ECETs (n = 28) from Head Start or state-funded centers serving low-income families. Developmental histories of ECETs regarding food and nutrition, beliefs about child nutrition, and teaching interactions related to food. Qualitative interviews were coded using a deductive content analysis approach. Three distinct interrelationships were observed across the themes. First, rules and routines regarding food and mealtime in the educators' childhood often aligned with educator beliefs and behaviors at meals in their classroom. Second, some ECETs described motivations to leave a healthy food legacy for children in their class. Finally, an experience of food insecurity appeared in narratives that also emphasized making sure children got enough through various strategies. The influence of ECET developmental histories and their related beliefs can be addressed through professional development and ongoing support. Future study should quantify model constructs in a larger sample and study their relationships over time. Copyright © 2017 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.

  20. Pharmacobezoars described and demystified.

    Science.gov (United States)

    Simpson, Serge-Emile

    2011-02-01

    A bezoar is a concretion of foreign material that forms and persists in the gastrointestinal tract. Bezoars are classified by their material origins. Phytobezoars contain plant material, trichobezoars contain hair, lactobezoars contain milk proteins, and pharmacobezoars contain pharmaceutical products. Tablets, suspensions, and even insoluble drug delivery vehicles can, on rare occasions, and sometimes under specific circumstances, form pharmacobezoars. The goal of this review is to catalog and examine all of the available reports in the English language medical literature that convincingly describe the formation and management of pharmacobezoars. Articles included in this review were identified by performing searches using the terms "bezoar," "pharmacobezoar," and "concretion" in the following databases: OVID MEDLINE, PubMed, and JSTOR. The complete MEDLINE and JSTOR holdings were included in the search without date ranges. The results were limited to English language publications. Articles that described nonmedication bezoars were not included in the review. Articles describing phytobezoars, food bezoars, fecal impactions, illicit drug packet ingestions, enteral feeding material bezoars, and hygroscopic diet aid bezoars were excluded. The bibliographic references within the articles already accumulated were then examined in order to gather additional pharmacobezoar cases. The cases are grouped by pharmaceutical agent that formed the bezoar, and groupings are arranged in alphabetical order. Discussions and conclusions specific to each pharmaceutical agent are included in that agent's subheading. Patterns and themes that emerged in the review of the assembled case reports are reviewed and presented in a more concise format. Pharmacobezoars form under a wide variety of circumstances and in a wide variety of patients. They are difficult to diagnose reliably. Rules for suspecting, diagnosing, and properly managing a pharmacobezoar are highly dependent on the

  1. Gravitational wave background from Standard Model physics: qualitative features

    International Nuclear Information System (INIS)

    Ghiglieri, J.; Laine, M.

    2015-01-01

    Because of physical processes ranging from microscopic particle collisions to macroscopic hydrodynamic fluctuations, any plasma in thermal equilibrium emits gravitational waves. For the largest wavelengths the emission rate is proportional to the shear viscosity of the plasma. In the Standard Model at 0T > 16 GeV, the shear viscosity is dominated by the most weakly interacting particles, right-handed leptons, and is relatively large. We estimate the order of magnitude of the corresponding spectrum of gravitational waves. Even though at small frequencies (corresponding to the sub-Hz range relevant for planned observatories such as eLISA) this background is tiny compared with that from non-equilibrium sources, the total energy carried by the high-frequency part of the spectrum is non-negligible if the production continues for a long time. We suggest that this may constrain (weakly) the highest temperature of the radiation epoch. Observing the high-frequency part directly sets a very ambitious goal for future generations of GHz-range detectors

  2. [Deep mycoses rarely described].

    Science.gov (United States)

    Charles, D

    1986-01-01

    Beside deep mycoses very well known: histoplasmosis, candidosis, cryptococcosis, there are other mycoses less frequently described. Some of them are endemic in some countries: South American blastomycosis in Brazil, coccidioidomycosis in California; some others are cosmopolitan and may affect everyone: sporotrichosis, or may affect only immunodeficient persons: mucormycosis. They do not spare Africa, we may encounter basidiobolomycosis, rhinophycomycosis, dermatophytosis, sporotrichosis and, more recently reported, rhinosporidiosis. Important therapeutic progresses have been accomplished with amphotericin B and with antifungus imidazole compounds (miconazole and ketoconazole). Surgical intervention is sometime recommended in chromomycosis and rhinosporidiosis.

  3. Low-dimensional models of ‘Neuro-glio-vascular unit’ for describing neural dynamics under normal and energy-starved conditions

    Directory of Open Access Journals (Sweden)

    Karishma eChhabria

    2016-03-01

    Full Text Available The motivation of developing simple minimal models for neuro-glio-vascular system arises from a recent modeling study elucidating the bidirectional information flow within the neuro-glio-vascular system having 89 dynamic equations (Chander and Chakravarthy 2012. While this was one of the first attempts at formulating a comprehensive model for neuro-glia-vascular system, it poses severe restrictions in scaling up to network levels. On the contrary, low dimensional models are convenient devices in simulating large networks that also provide an intuitive understanding of the complex interactions occurring within the neuro-glio-vascular system. The key idea underlying the proposed models is to describe the glio-vascular system as a lumped system which takes neural firing rate as input and returns an ‘energy’ variable (analogous to ATP as output. To this end we present two models: Biophysical neuro-energy (Model #1 with 5 variables, comprising of KATP channel activity governed by neuronal ATP dynamics and the Dynamic threshold (Model #2 with 3 variables depicting the dependence of neural firing threshold on the ATP dynamics. Both the models show different firing regimes such as continuous spiking, phasic and tonic bursting depending on the ATP production coefficient, εp and external current. We then demonstrate that in a network comprising of such energy-dependent neuron units, εp could modulate the Local field potential (LFP frequency and amplitude. Interestingly, low frequency LFP dominates under low εp conditions, which is thought to be reminiscent of seizure-like activity observed in epilepsy. The proposed ‘neuron-energy’ unit may be implemented in building models of neuro-glio-vascular networks to simulate data obtained from multimodal neuroimaging systems such as fNIRS-EEG and fMRI-EEG. Such models could also provide a theoretical basis for devising optimal neurorehabilitation strategies such as non-invasive brain stimulation for

  4. Low-Dimensional Models of "Neuro-Glio-Vascular Unit" for Describing Neural Dynamics under Normal and Energy-Starved Conditions.

    Science.gov (United States)

    Chhabria, Karishma; Chakravarthy, V Srinivasa

    2016-01-01

    The motivation of developing simple minimal models for neuro-glio-vascular (NGV) system arises from a recent modeling study elucidating the bidirectional information flow within the NGV system having 89 dynamic equations (1). While this was one of the first attempts at formulating a comprehensive model for neuro-glio-vascular system, it poses severe restrictions in scaling up to network levels. On the contrary, low--dimensional models are convenient devices in simulating large networks that also provide an intuitive understanding of the complex interactions occurring within the NGV system. The key idea underlying the proposed models is to describe the glio-vascular system as a lumped system, which takes neural firing rate as input and returns an "energy" variable (analogous to ATP) as output. To this end, we present two models: biophysical neuro-energy (Model 1 with five variables), comprising KATP channel activity governed by neuronal ATP dynamics, and the dynamic threshold (Model 2 with three variables), depicting the dependence of neural firing threshold on the ATP dynamics. Both the models show different firing regimes, such as continuous spiking, phasic, and tonic bursting depending on the ATP production coefficient, ɛp, and external current. We then demonstrate that in a network comprising such energy-dependent neuron units, ɛp could modulate the local field potential (LFP) frequency and amplitude. Interestingly, low-frequency LFP dominates under low ɛp conditions, which is thought to be reminiscent of seizure-like activity observed in epilepsy. The proposed "neuron-energy" unit may be implemented in building models of NGV networks to simulate data obtained from multimodal neuroimaging systems, such as functional near infrared spectroscopy coupled to electroencephalogram and functional magnetic resonance imaging coupled to electroencephalogram. Such models could also provide a theoretical basis for devising optimal neurorehabilitation strategies, such as

  5. Brandon mathematical model describing the effect of calcination and reduction parameters on specific surface area of UO{sub 2} powders

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Nguyen Trong; Thuan, Le Ba [Institute for Technology of Radioactive and Rare Elements (ITRRE), 48 Lang Ha, Dong Da, Ha Noi (Viet Nam); Van Khoai, Do [Micro-Emission Ltd., 1-1 Asahidai, Nomi, Ishikawa, 923-1211 (Japan); Lee, Jin-Young, E-mail: jinlee@kigam.re.kr [Convergence Research Center for Development of Mineral Resources (DMR), Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon, 305-350 (Korea, Republic of); Jyothi, Rajesh Kumar, E-mail: rkumarphd@kigam.re.kr [Convergence Research Center for Development of Mineral Resources (DMR), Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon, 305-350 (Korea, Republic of)

    2016-06-15

    Uranium dioxide (UO{sub 2}) powder has been widely used to prepare fuel pellets for commercial light water nuclear reactors. Among typical characteristics of the powder, specific surface area (SSA) is one of the most important parameter that determines the sintering ability of UO{sub 2} powder. This paper built up a mathematical model describing the effect of the fabrication parameters on SSA of UO{sub 2} powders. To the best of our knowledge, the Brandon model is used for the first time to describe the relationship between the essential fabrication parameters [reduction temperature (T{sub R}), calcination temperature (T{sub C}), calcination time (t{sub C}) and reduction time (t{sub R})] and SSA of the obtained UO{sub 2} powder product. The proposed model was tested with Wilcoxon's rank sum test, showing a good agreement with the experimental parameters. The proposed model can be used to predict and control the SSA of UO{sub 2} powder.

  6. A plant-wide aqueous phase chemistry module describing pH variations and ion speciation/pairing in wastewater treatment process models.

    Science.gov (United States)

    Flores-Alsina, Xavier; Kazadi Mbamba, Christian; Solon, Kimberly; Vrecko, Darko; Tait, Stephan; Batstone, Damien J; Jeppsson, Ulf; Gernaey, Krist V

    2015-11-15

    There is a growing interest within the Wastewater Treatment Plant (WWTP) modelling community to correctly describe physico-chemical processes after many years of mainly focusing on biokinetics. Indeed, future modelling needs, such as a plant-wide phosphorus (P) description, require a major, but unavoidable, additional degree of complexity when representing cationic/anionic behaviour in Activated Sludge (AS)/Anaerobic Digestion (AD) systems. In this paper, a plant-wide aqueous phase chemistry module describing pH variations plus ion speciation/pairing is presented and interfaced with industry standard models. The module accounts for extensive consideration of non-ideality, including ion activities instead of molar concentrations and complex ion pairing. The general equilibria are formulated as a set of Differential Algebraic Equations (DAEs) instead of Ordinary Differential Equations (ODEs) in order to reduce the overall stiffness of the system, thereby enhancing simulation speed. Additionally, a multi-dimensional version of the Newton-Raphson algorithm is applied to handle the existing multiple algebraic inter-dependencies. The latter is reinforced with the Simulated Annealing method to increase the robustness of the solver making the system not so dependent of the initial conditions. Simulation results show pH predictions when describing Biological Nutrient Removal (BNR) by the activated sludge models (ASM) 1, 2d and 3 comparing the performance of a nitrogen removal (WWTP1) and a combined nitrogen and phosphorus removal (WWTP2) treatment plant configuration under different anaerobic/anoxic/aerobic conditions. The same framework is implemented in the Benchmark Simulation Model No. 2 (BSM2) version of the Anaerobic Digestion Model No. 1 (ADM1) (WWTP3) as well, predicting pH values at different cationic/anionic loads. In this way, the general applicability/flexibility of the proposed approach is demonstrated, by implementing the aqueous phase chemistry module in some

  7. Teaching Qualitative Research for Human Services Students: A Three-Phase Model

    Science.gov (United States)

    Goussinsky, Ruhama; Reshef, Arie; Yanay-Ventura, Galit; Yassour-Borochowitz, Dalit

    2011-01-01

    Qualitative research is an inherent part of the human services profession, since it emphasizes the great and multifaceted complexity characterizing human experience and the sociocultural context in which humans act. In the department of human services at Emek Yezreel College, Israel, we have developed a three-phase model to ensure a relatively…

  8. Disease management projects and the Chronic CareModel in action: Baseline qualitative research

    NARCIS (Netherlands)

    B.J. Hipple Walters (Bethany); S.A. Adams (Samantha); A.P. Nieboer (Anna); R.A. Bal (Roland)

    2012-01-01

    textabstractBackground: Disease management programs, especially those based on the Chronic Care Model (CCM),are increasingly common in the Netherlands. While disease management programs have beenwell-researched quantitatively and economically, less qualitative research has been done. Theoverall aim

  9. Towards a structured approach to building qualitative reasoning models and simulations

    NARCIS (Netherlands)

    Bredeweg, B.; Salles, P.; Bouwer, A.; Liem, J.; Nuttle, T.; Cioca, E.; Nakova, E.; Noble, R.; Caldas, A.L.R.; Uzunov, Y.; Varadinova, E.; Zitek, A.

    2008-01-01

    Successful transfer and uptake of qualitative reasoning technology for modelling and simulation in a variety of domains has been hampered by the lack of a structured methodology to support formalisation of ideas. We present a framework that structures and supports the capture of conceptual knowledge

  10. Pseudospin model to describe transport properties in Bi2Sr2(CazPr1-z)Cu2O8+y

    International Nuclear Information System (INIS)

    Bastone, E.C.; Pires, A.S.T.; Silva, P.R.

    2001-01-01

    A pseudo-spin model is proposed, as a means to describe some transport properties (resistivity and Hall mobility) in Bi 2 Sr 2 (Ca z Pr 1-z )Cu 2 O 8+y . Our model is based in a double-well potential where tunneling in a given site and interaction between different lattice sites are allowed only through the excited states. Doping of the pure system by the addition of Pr increases the ratio between the activation energy and the tunneling constant. The model Hamiltonian displays some features which are present in the hydrogen-bonded ferroelectrics. Its dynamics is treated in the random phase approximation and the characteristic frequency (time) is used in a Drude formula in order to obtain some transport properties of the system, namely the electric resistivity and the Hall mobility. The quantities calculated in this work are compared with the experimental data given by Beschoten et al. (1996). (orig.)

  11. LANDPLANER (LANDscape, Plants, LANdslide and ERosion): a model to describe the dynamic response of slopes (or basins) under different changing scenarios

    Science.gov (United States)

    Rossi, Mauro; Torri, Dino; Santi, Elisa; Bacaro, Giovanni; Marchesini, Ivan

    2014-05-01

    approaches have been proposed to model separately landslide and erosion processes, only few attempts were made to model both jointly, mostly integrating pre-existing models. To overcome this limitation we develop a new model called LANDPLANER (LANDscape, Plants, LANdslide and ERosion), specifically design to describe the dynamic response of slopes (or basins) under different changing scenarios including: (i) changes of meteorological factors, (ii) changes of vegetation or land-use, (iii) and changes of slope morphology. The was applied in different study area in order to check its basic assumptions, and to test its general operability and applicability. Results show a reasonable model behaviors and confirm its easy applicability in real cases.

  12. Secondary Science Teachers Making Sense of Model-Based Classroom Instruction: Understanding the Learning and Learning Pathways Teachers Describe as Supporting Changes in Teaching Practice

    Science.gov (United States)

    Hvidsten, Connie J.

    Connie J. Hvidsten September 2016 Education Secondary Science Teachers Making Sense of Model-Based Classroom Instruction: Understanding the Learning and Learning Pathways Teachers Describe as Supporting Changes in Teaching Practice This dissertation consists of three papers analyzing writings and interviews of experienced secondary science teachers during and after a two-year professional development (PD) program focused on model-based reasoning (MBR). MBR is an approach to science instruction that provides opportunities for students to use conceptual models to make sense of natural phenomena in ways that are similar to the use of models within the scientific community. The aim of this research is to better understand the learning and learning pathways teachers identified as valuable in supporting changes in their teaching practice. To accomplish this aim, the papers analyze the ways teachers 1) ascribe their learning to various aspects of the program, 2) describe what they learned, and 3) reflect on the impact the PD had on their teaching practice. Twenty-one secondary science teachers completed the Innovations in Science Instruction through Modeling (ISIM) program from 2007 through 2009. Commonalities in the written reflections and interview responses led to a set of generalizable findings related to the impacts and outcomes of the PD. The first of the three papers describes elements of the ISIM program that teachers associated with their own learning. One of the most frequently mentioned PD feature was being in the position of an adult learner. Embedding learning in instructional practice by collaboratively developing and revising lessons, and observing the lessons in one-another's classrooms provided a sense of professional community, accountability, and support teachers reported were necessary to overcome the challenges of implementing new pedagogical practices. Additionally, teachers described that opportunities to reflect on their learning and connect their

  13. WE-AB-BRA-02: Development of Biomechanical Models to Describe Dose-Volume Response to Liver Stereotactic Body Radiation Therapy (SBRT) Patients

    International Nuclear Information System (INIS)

    McCulloch, M; Polan, D; Feng, M; Lawrence, T; Haken, R Ten; Brock, K

    2015-01-01

    Purpose: Previous studies have shown that radiotherapy treatment for liver metastases causes marked liver hypertrophy in areas receiving low dose and atrophy/fibrosis in areas receiving high dose. The purpose of this work is to develop and evaluate a biomechanical model-based dose-response model to describe these liver responses to SBRT. Methods: In this retrospective study, a biomechanical model-based deformable registration algorithm, Morfeus, was expanded to include dose-based boundary conditions. Liver and tumor volumes were contoured on the planning images and CT/MR images three months post-RT and converted to finite element models. A thermal expansion-based relationship correlating the delivered dose and volume response was generated from 22 patients previously treated. This coefficient, combined with the planned dose, was applied as an additional boundary condition to describe the volumetric response of the liver of an additional cohort of metastatic liver patients treated with SBRT. The accuracy of the model was evaluated based on overall volumetric liver comparisons and the target registration error (TRE) using the average deviations in positions of identified vascular bifurcations on each set of registered images, with a target accuracy of the 2.5mm isotropic dose grid (vector dimension 4.3mm). Results: The thermal expansion coefficient models the volumetric change of the liver to within 3%. The accuracy of Morfeus with dose-expansion boundary conditions a TRE of 5.7±2.8mm compared to 11.2±3.7mm using rigid registration and 8.9±0.28mm using Morfeus with only spatial boundary conditions. Conclusion: A biomechanical model has been developed to describe the volumetric and spatial response of the liver to SBRT. This work will enable the improvement of correlating functional imaging with delivered dose, the mapping of the delivered dose from one treatment onto the planning images for a subsequent treatment, and will further provide information to assist

  14. New Described Dermatological Disorders

    Directory of Open Access Journals (Sweden)

    Müzeyyen Gönül

    2014-01-01

    Full Text Available Many advances in dermatology have been made in recent years. In the present review article, newly described disorders from the last six years are presented in detail. We divided these reports into different sections, including syndromes, autoinflammatory diseases, tumors, and unclassified disease. Syndromes included are “circumferential skin creases Kunze type” and “unusual type of pachyonychia congenita or a new syndrome”; autoinflammatory diseases include “chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE syndrome,” “pyoderma gangrenosum, acne, and hidradenitis suppurativa (PASH syndrome,” and “pyogenic arthritis, pyoderma gangrenosum, acne, and hidradenitis suppurativa (PAPASH syndrome”; tumors include “acquired reactive digital fibroma,” “onychocytic matricoma and onychocytic carcinoma,” “infundibulocystic nail bed squamous cell carcinoma,” and “acral histiocytic nodules”; unclassified disorders include “saurian papulosis,” “symmetrical acrokeratoderma,” “confetti-like macular atrophy,” and “skin spicules,” “erythema papulosa semicircularis recidivans.”

  15. Qualitative cosmology

    International Nuclear Information System (INIS)

    Khalatnikov, I.M.; Belinskij, V.A.

    1984-01-01

    Application of the qualitative theory of dynamic systems to analysis of homogeneous cosmological models is described. Together with the well-known cases, requiring ideal liquid, the properties of cosmological evolution of matter with dissipative processes due to viscosity are considered. New cosmological effects occur, when viscosity terms being one and the same order with the rest terms in the equations of gravitation or even exceeding them. In these cases the description of the dissipative process by means of only two viscosity coefficients (volume and shift) may become inapplicable because all the rest decomposition terms of dissipative addition to the energy-momentum in velocity gradient can be large application of equations with hydrodynamic viscosty should be considered as a model of dissipative effects in cosmology

  16. Statistical Methods for the Qualitative Assessment of Dynamic Models with Time Delay (R Package qualV

    Directory of Open Access Journals (Sweden)

    Stefanie Jachner

    2007-06-01

    Full Text Available Results of ecological models differ, to some extent, more from measured data than from empirical knowledge. Existing techniques for validation based on quantitative assessments sometimes cause an underestimation of the performance of models due to time shifts, accelerations and delays or systematic differences between measurement and simulation. However, for the application of such models it is often more important to reproduce essential patterns instead of seemingly exact numerical values. This paper presents techniques to identify patterns and numerical methods to measure the consistency of patterns between observations and model results. An orthogonal set of deviance measures for absolute, relative and ordinal scale was compiled to provide informations about the type of difference. Furthermore, two different approaches accounting for time shifts were presented. The first one transforms the time to take time delays and speed differences into account. The second one describes known qualitative criteria dividing time series into interval units in accordance to their main features. The methods differ in their basic concepts and in the form of the resulting criteria. Both approaches and the deviance measures discussed are implemented in an R package. All methods are demonstrated by means of water quality measurements and simulation data. The proposed quality criteria allow to recognize systematic differences and time shifts between time series and to conclude about the quantitative and qualitative similarity of patterns.

  17. A qualitative description of falls in a neuro-rehabilitation unit: the use of a standardised fall report including the International Classification of Functioning (ICF) to describe activities and environmental factors.

    Science.gov (United States)

    Saverino, Alessia; Moriarty, Amy; Rantell, Khadija; Waller, Denise; Ayres, Rachael; Playford, Diane

    2015-01-01

    Falls are a recognised problem for people with long-term neurological conditions but less is known about fall risk in young adults. This study describes fallers' and falls' characteristics in adults less than 60 years old, in a neuro-rehabilitation unit. This single-centre, longitudinal, observational study included 114 consecutive admissions to a UK neuro-rehabilitation unit over 20 months. The demographic and clinical characteristics of eligible patients included age, sex, diagnosis, hospital length of stay and the Functional Independence Measure (FIM). Falls were recorded prospectively in a fall report, using the activities and environmental domains of the International Classification of Functioning (ICF). A total of 34 (30%) patients reported a fall, with 50% experiencing more than one fall. The majority of falls (60%) occurred during the first 2 weeks, during day-time (90%) and during mobile activities (70%). Overall, falls rate (95% confidence interval) was 1.33 (1.04 to 1.67) per 100 d of patient hospital stay. Factors associated with increased falls included becoming a walker during admission or being cognitively impaired. There were no serious fall-related injuries. The first 2 weeks of admission is a high risk time for fallers, in particular those who become walkers or are cognitively impaired. Prevention policies should be put in place based on fall characteristics. Implications for Rehabilitation The ICF is a valuable instrument for describing subject and environmental factors during a fall-event. Falls are frequent events but do not usually cause serious injuries during inpatient rehabilitation. There is an increased fall risk for subjects with cognitive impairments or those relearning how to walk.

  18. A plant-wide aqueous phase chemistry module describing pH variations and ion speciation/pairing in wastewater treatment process models

    DEFF Research Database (Denmark)

    Flores Alsina, Xavier; Kazadi Mbamba, Christian; Solon, Kimberly

    2015-01-01

    at different cationic/anionic loads. In this way, the general applicability/flexibility of the proposed approach is demonstrated, by implementing the aqueous phase chemistry module in some of the most frequently used WWTP process simulation models. Finally, it is shown how traditional wastewater modelling......, but unavoidable, additional degree of complexity when representing cationic/anionic behaviour in Activated Sludge (AS)/Anaerobic Digestion (AD) systems. In this paper, a plant-wide aqueous phase chemistry module describing pH variations plus ion speciation/pairing is presented and interfaced with industry......) in order to reduce the overall stiffness of the system, thereby enhancing simulation speed. Additionally, a multi-dimensional version of the Newton-Raphson algorithm is applied to handle the existing multiple algebraic inter-dependencies. The latter is reinforced with the Simulated Annealing method...

  19. Unifying Pore Network Modeling, Continuous Time Random Walk (CTRW) Theory and Experiment to Describe Impact of Spatial Heterogeneities on Solute Dispersion at Multiple Length-scales

    Science.gov (United States)

    Bijeljic, B.; Blunt, M. J.; Rhodes, M. E.

    2009-04-01

    This talk will describe and highlight the advantages offered by a novel methodology that unifies pore network modeling, CTRW theory and experiment in description of solute dispersion in porous media. Solute transport in a porous medium is characterized by the interplay of advection and diffusion (described by Peclet number, Pe) that cause dispersion of solute particles. Dispersion is traditionally described by dispersion coefficients, D, that are commonly calculated from the spatial moments of the plume. Using a pore-scale network model based on particle tracking, the rich Peclet-number dependence of dispersion coefficient is predicted from first principles and is shown to compare well with experimental data for restricted diffusion, transition, power-law and mechanical dispersion regimes in the asymptotic limit. In the asymptotic limit D is constant and can be used in an averaged advection-dispersion equation. However, it is highly important to recognize that, until the velocity field is fully sampled, the particle transport is non-Gaussian and D possesses temporal or spatial variation. Furthermore, temporal probability density functions (PDF) of tracer particles are studied in pore networks and an excellent agreement for the spectrum of transition times for particles from pore to pore is obtained between network model results and CTRW theory. Based on the truncated power-law interpretation of PDF-s, the physical origin of the power-law scaling of dispersion coefficient vs. Peclet number has been explained for unconsolidated porous media, sands and a number of sandstones, arriving at the same conclusion from numerical network modelling, analytic CTRW theory and experiment. The length traveled by solute plumes before Gaussian behaviour is reached increases with an increase in heterogeneity and/or Pe. This opens up the question on the nature of dispersion in natural systems where the heterogeneities at the larger scales will significantly increase the range of

  20. A qualitative model of limiting factors for a salmon life cycle in the context of river rehabilitation

    NARCIS (Netherlands)

    Noble, R.A.A.; Bredeweg, B.; Linnebank, F.; Salles, P.; Cowx, I.G.

    2009-01-01

    Qualitative Reasoning modelling has been promoted as a tool for formalising, integrating and exploring conceptual knowledge in ecological systems, such as river rehabilitation, which draw different information from multiple domains. A qualitative model was developed in Garp3 to capture and formalise

  1. A CFBPN Artificial Neural Network Model for Educational Qualitative Data Analyses: Example of Students' Attitudes Based on Kellerts' Typologies

    Science.gov (United States)

    Yorek, Nurettin; Ugulu, Ilker

    2015-01-01

    In this study, artificial neural networks are suggested as a model that can be "trained" to yield qualitative results out of a huge amount of categorical data. It can be said that this is a new approach applied in educational qualitative data analysis. In this direction, a cascade-forward back-propagation neural network (CFBPN) model was…

  2. Empirical model based on Weibull distribution describing the destruction kinetics of natural microbiota in pineapple (Ananas comosus L.) puree during high-pressure processing.

    Science.gov (United States)

    Chakraborty, Snehasis; Rao, Pavuluri Srinivasa; Mishra, Hari Niwas

    2015-10-15

    High pressure inactivation of natural microbiota viz. aerobic mesophiles (AM), psychrotrophs (PC), yeasts and molds (YM), total coliforms (TC) and lactic acid bacteria (LAB) in pineapple puree was studied within the experimental domain of 0.1-600 MPa and 30-50 °C with a treatment time up to 20 min. A complete destruction of yeasts and molds was obtained at 500 MPa/50 °C/15 min; whereas no counts were detected for TC and LAB at 300 MPa/30 °C/15 min. A maximum of two log cycle reductions was obtained for YM during pulse pressurization at the severe process intensity of 600 MPa/50 °C/20 min. The Weibull model clearly described the non-linearity of the survival curves during the isobaric period. The tailing effect, as confirmed by the shape parameter (β) of the survival curve, was obtained in case of YM (β1) was observed for the other microbial groups. Analogous to thermal death kinetics, the activation energy (Ea, kJ·mol(-1)) and the activation volume (Va, mL·mol(-1)) values were computed further to describe the temperature and pressure dependencies of the scale parameter (δ, min), respectively. A higher δ value was obtained for each microbe at a lower temperature and it decreased with an increase in pressure. A secondary kinetic model was developed describing the inactivation rate (k, min(-1)) as a function of pressure (P, MPa) and temperature (T, K) including the dependencies of Ea and Va on P and T, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. CAMDYN: a new model to describe the axial motion of molten fuel inside the pin of a fast breeder reactor during accident conditions

    International Nuclear Information System (INIS)

    Peter, G.

    1991-01-01

    The new in-pin fuel motion model CAMDYN (Cavity Material Dynamics) describes the axial motion of both partially and fully molten fuel inside the pin of a fast breeder reactor during accident conditions. The motion of the two types of molten fuel and the imbedded fission gas bubbles is treated both before and after cladding failure. The basic modelling approach consists of the treatment of two one-dimensional flows which are coupled by interaction terms. Each of these flows is treated compressively and with axially variable flow cross sections. The mass and energy equations of both fields are solved explicitly using upwind differencing on a fixed Eulerian grid. The two momentum equations are solved simultaneously, using the convective momentum fluxes of the previous timestep. Both partially and fully molten fuel can move axially into a central hole extending to the plenum in the case of certain hollow pellet designs. The fuel temperature calculation includes the determination of a radial temperature profile. A simple conduction freezing model is included. After cladding failure, ejection into the coolant channel is modeled

  4. Understanding communication between emergency and consulting physicians: a qualitative study that describes and defines the essential elements of the emergency department consultation-referral process for the junior learner.

    Science.gov (United States)

    Chan, Teresa; Orlich, Donika; Kulasegaram, Kulamakan; Sherbino, Jonathan

    2013-01-01

    To define the important elements of an emergency department (ED) consultation request and to develop a simple model of the process. From March to September 2010, 61 physicians (21 emergency medicine [EM], 20 general surgery [GS], 20 internal medicine [IM]; 31 residents, 30 attending staff) were questioned about how junior learners should be taught about ED consultation. Two investigators independently reviewed focus group and interview transcripts using grounded theory to generate an index of themes until saturation was reached. Disagreements were resolved by consensus, yielding an inventory of themes and subthemes. All transcripts were coded using this index of themes; 30% of transcripts were coded in duplicate to determine the agreement. A total of 245 themes and subthemes were identified. The agreement between reviewers was 77%. Important themes in the process were as follows: initial preparation and review of investigations by EM physician (overall endorsement 87% [range 70-100% in different groups]); identification of involved parties (patient and involved physicians) (100%); hypothesis of patient's diagnosis (75% [range 62-83%]) or question for the consulting physician (70% [range 55-95%]); urgency (100%) and stability (74% [range 62-80%]); questions from the consultant (100%); discussion/communication (98% [range 95-100%]); and feedback (98% [range 95-100%]). These components were reorganized into a simple framework (PIQUED). Each clinical specialty significantly contributed to the model (χ2  =  7.9; p value  =  0.019). Each group contributed uniquely to the final list of important elements (percent contributions: EM, 57%; GS, 41%; IM, 64%). We define important elements of an ED consultation with input from emergency and consulting physicians. We propose a model that organizes these elements into a simple framework (PIQUED) that may be valuable for junior learners.

  5. Biodiversity and soil quality in agroecosystems: the use of a qualitative multi-attribute model

    DEFF Research Database (Denmark)

    Cortet, J.; Bohanec, M.; Griffiths, B.

    2009-01-01

    In ecological impact assessment, special emphasis is put on soil biology and estimating soil quality from the observed biological parameters. The aim of this study is to propose a tool easy to use for scientists and decision makers for agroecosystems soil quality assessment using these biological...... parameters. This tool was developed as a collaboration between ECOGEN (www.ecogen.dk) soil experts and decision analysts. Methodologically, we have addressed this goal using model-based Decision Support Systems (DSS), taking the approach of qualitative multi-attribute modelling. The approach is based...... on developing various hierarchical multiattribute models that consist of qualitative attributes and utility (aggregation) functions, represented by decision rules. The assessment of soil quality is based on two main indicators: (1) soil diversity (assessed through microfauna, mesofauna and macrofauna richness...

  6. COGNITIVE MODELING AS A METHOD OF QUALITATIVE ANALYSIS OF IT PROJECTS

    Directory of Open Access Journals (Sweden)

    Інна Ігорівна ОНИЩЕНКО

    2016-03-01

    Full Text Available The example project implementing automated CRM-system demonstrated the possibility and features of cognitive modeling in the qualitative analysis of project risks to determine their additional features. Proposed construction of cognitive models of project risks in information technology within the qualitative risk analysis, additional assessments as a method of ranking risk to characterize the relationship between them. The proposed cognitive model reflecting the relationship between the risk of IT project to assess the negative and the positive impact of certain risks for the remaining risks of project implementation of the automated CRM-system. The ability to influence the risk of a fact of other project risks can increase the priority of risk with low impact on results due to its relationship with other project risks.

  7. Global Qualitative Flow-Path Modeling for Local State Determination in Simulation and Analysis

    Science.gov (United States)

    Malin, Jane T. (Inventor); Fleming, Land D. (Inventor)

    1998-01-01

    For qualitative modeling and analysis, a general qualitative abstraction of power transmission variables (flow and effort) for elements of flow paths includes information on resistance, net flow, permissible directions of flow, and qualitative potential is discussed. Each type of component model has flow-related variables and an associated internal flow map, connected into an overall flow network of the system. For storage devices, the implicit power transfer to the environment is represented by "virtual" circuits that include an environmental junction. A heterogeneous aggregation method simplifies the path structure. A method determines global flow-path changes during dynamic simulation and analysis, and identifies corresponding local flow state changes that are effects of global configuration changes. Flow-path determination is triggered by any change in a flow-related device variable in a simulation or analysis. Components (path elements) that may be affected are identified, and flow-related attributes favoring flow in the two possible directions are collected for each of them. Next, flow-related attributes are determined for each affected path element, based on possibly conflicting indications of flow direction. Spurious qualitative ambiguities are minimized by using relative magnitudes and permissible directions of flow, and by favoring flow sources over effort sources when comparing flow tendencies. The results are output to local flow states of affected components.

  8. A parametric model to describe neutron spectra around high-energy electron accelerators and its application in neutron spectrometry with Bonner Spheres

    Science.gov (United States)

    Bedogni, Roberto; Pelliccioni, Maurizio; Esposito, Adolfo

    2010-03-01

    Due to the increased interest of the scientific community in the applications of synchrotron light, there is an increasing demand of high-energy electron facilities, testified by the construction of several new facilities worldwide. The radiation protection around such facilities requires accurate experimental methods to determine the dose due to prompt radiation fields. Neutron fields, in particular, are the most complex to measure, because they extend in energy from thermal (10 -8 MeV) up to hundreds MeV and because the responses of dosemeters and survey meters usually have large energy dependence. The Bonner Spheres Spectrometer (BSS) is in practice the only instrument able to respond over the whole energy range of interest, and for this reason it is frequently used to derive neutron spectra and dosimetric quantities in accelerator workplaces. Nevertheless, complex unfolding algorithms are needed to derive the neutron spectra from the experimental BSS data. This paper presents a parametric model specially developed for the unfolding of the experimental data measured with BSS around high-energy electron accelerators. The work consists of the following stages: (1) Generation with the FLUKA code, of a set of neutron spectra representing the radiation environment around accelerators with different electron energies; (2) formulation of a parametric model able to describe these spectra, with particular attention to the high-energy component (>10 MeV), which may be responsible for a large part of the dose in workplaces; and (3) implementation of this model in an existing unfolding code.

  9. A parametric model to describe neutron spectra around high-energy electron accelerators and its application in neutron spectrometry with Bonner Spheres

    International Nuclear Information System (INIS)

    Bedogni, Roberto; Pelliccioni, Maurizio; Esposito, Adolfo

    2010-01-01

    Due to the increased interest of the scientific community in the applications of synchrotron light, there is an increasing demand of high-energy electron facilities, testified by the construction of several new facilities worldwide. The radiation protection around such facilities requires accurate experimental methods to determine the dose due to prompt radiation fields. Neutron fields, in particular, are the most complex to measure, because they extend in energy from thermal (10 -8 MeV) up to hundreds MeV and because the responses of dosemeters and survey meters usually have large energy dependence. The Bonner Spheres Spectrometer (BSS) is in practice the only instrument able to respond over the whole energy range of interest, and for this reason it is frequently used to derive neutron spectra and dosimetric quantities in accelerator workplaces. Nevertheless, complex unfolding algorithms are needed to derive the neutron spectra from the experimental BSS data. This paper presents a parametric model specially developed for the unfolding of the experimental data measured with BSS around high-energy electron accelerators. The work consists of the following stages: (1) Generation with the FLUKA code, of a set of neutron spectra representing the radiation environment around accelerators with different electron energies; (2) formulation of a parametric model able to describe these spectra, with particular attention to the high-energy component (>10 MeV), which may be responsible for a large part of the dose in workplaces; and (3) implementation of this model in an existing unfolding code.

  10. Qualitative analysis of nonlinear incidence rate upon the behaviour of an epidemiological model

    International Nuclear Information System (INIS)

    Li Xiaogui.

    1988-12-01

    Two theorems concerning the solutions of the system of differential equations describing an epidemiological model with nonlinear incidence rate per infective individual are demonstrated. 2 refs, 1 fig

  11. The explanatory models of depression and anxiety in primary care: a qualitative study from India

    Directory of Open Access Journals (Sweden)

    Andrew Gracy

    2012-09-01

    Full Text Available Abstract Background The biggest barrier to treatment of common mental disorders in primary care settings is low recognition among health care providers. This study attempts to explore the explanatory models of common mental disorders (CMD with the goal of identifying how they could help in improving the recognition, leading to effective treatment in primary care. Results The paper describes findings of a cross sectional qualitative study nested within a large randomized controlled trial (the Manas trial. Semi structured interviews were conducted with 117 primary health care attendees (30 males and 87 females suffering from CMD. Main findings of the study are that somatic phenomena were by far the most frequent presenting problems; however, psychological phenomena were relatively easily elicited on probing. Somatic phenomena were located within a biopsychosocial framework, and a substantial proportion of informants used the psychological construct of ‘tension’ or ‘worry’ to label their illness, but did not consider themselves as suffering from a ‘mental disorder’. Very few gender differences were observed in the descriptions of symptoms but at the same time the pattern of adverse life events and social difficulties varied across gender. Conclusion Our study demonstrates how people present their illness through somatic complaints but clearly link their illness to their psychosocial world. However they do not associate their illness to a ‘mental disorder’ and this is an important phenomenon that needs to be recognized in management of CMD in primary settings. Our study also elicits important gender differences in the experience of CMD.

  12. The development of a qualitative dynamic attribute value model for healthcare institutes.

    Science.gov (United States)

    Lee, Wan-I

    2010-01-01

    Understanding customers has become an urgent topic for increasing competitiveness. The purpopse of the study was to develop a qualitative dynamic attribute value model which provides insight into the customers' value for healthcare institute managers by conducting the initial open-ended questionnaire survey to select participants purposefully. A total number of 427 questionnaires was conducted in two hospitals in Taiwan (one district hospital with 635 beds and one academic hospital with 2495 beds) and 419 questionnaires were received in nine weeks. Then, apply qualitative in-depth interviews to explore customers' perspective of values for building a model of partial differential equations. This study concludes nine categories of value, including cost, equipment, physician background, physicain care, environment, timing arrangement, relationship, brand image and additional value, to construct objective network for customer value and qualitative dynamic attribute value model where the network shows the value process of loyalty development via its effect on customer satisfaction, customer relationship, customer loyalty and healthcare service. One set predicts the customer relationship based on comminent, including service quality, communication and empahty. As the same time, customer loyalty based on trust, involves buzz marketing, brand and image. Customer value of the current instance is useful for traversing original customer attributes and identifing customers on different service share.

  13. A Weibull model to describe antimicrobial kinetics of oregano and lemongrass essential oils against Salmonella Enteritidis in ground beef during refrigerated storage.

    Science.gov (United States)

    de Oliveira, Thales Leandro Coutinho; Soares, Rodrigo de Araújo; Piccoli, Roberta Hilsdorf

    2013-03-01

    The antimicrobial effect of oregano (Origanum vulgare L.) and lemongrass (Cymbopogon citratus (DC.) Stapf.) essential oils (EOs) against Salmonella enterica serotype Enteritidis in in vitro experiments, and inoculated in ground bovine meat during refrigerated storage (4±2 °C) for 6 days was evaluated. The Weibull model was tested to fit survival/inactivation bacterial curves (estimating of p and δ parameters). The minimum inhibitory concentration (MIC) value for both EOs on S. Enteritidis was 3.90 μl/ml. The EO concentrations applied in the ground beef were 3.90, 7.80 and 15.60 μl/g, based on MIC levels and possible activity reduction by food constituents. Both evaluated EOs in all tested levels, showed antimicrobial effects, with microbial populations reducing (p≤0.05) along time storage. Evaluating fit-quality parameters (RSS and RSE) Weibull models are able to describe the inactivation curves of EOs against S. Enteritidis. The application of EOs in processed meats can be used to control pathogens during refrigerated shelf-life. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Extending a model of precarious employment: A qualitative study of immigrant workers in Spain.

    Science.gov (United States)

    Porthé, Victoria; Ahonen, Emily; Vázquez, M Luisa; Pope, Catherine; Agudelo, Andrés Alonso; García, Ana M; Amable, Marcelo; Benavides, Fernando G; Benach, Joan

    2010-04-01

    Since the 1980s, changes in the labor market have modified power relations between capital and labor, leading to greater levels of precarious employment among workers. Globalization has led to a growth in migration, as people leave their countries in search of work. We aimed to describe the dimensions of precarious employment for immigrant workers in Spain. Qualitative study using analytic induction. Criterion sampling was used to recruit 129 immigrant workers in Spain with documented and undocumented administrative status. Data quality was ensured by triangulation. Immigrant workers reported that precarious employment is characterized by high job instability, a lack of power for negotiating employment conditions, and defenselessness against high labor demands. They described insufficient wages, long working hours, limited social benefits, and difficulty in exercising their rights. Undocumented workers reported greater defenselessness and worse employment conditions. This study allowed us to describe the dimensions of precarious employment in immigrant workers. (c) 2010 Wiley-Liss, Inc.

  15. "Personified as Paragon of Suffering...... Optimistic Being of Achieving Normalcy:" A Conceptual Model Derived from Qualitative Research

    Science.gov (United States)

    Nayak, Shalini G; Pai, Mamatha Shivananda; George, Linu Sara

    2018-01-01

    Background: Conceptual models developed through qualitative research are based on the unique experiences of suffering and individuals’ adoptions of each participant. A wide array of problems are faced by head-and-neck cancer (HNC) patients due to disease pathology and treatment modalities which are sufficient to influence the quality of life (QOL). Men possess greater self-acceptance and are better equipped with intrapersonal strength to cope with stress and adequacy compared to women. Methodology: A qualitative phenomenology study was conducted among seven women suffering from HNC, with the objective to understand their experiences of suffering and to describe the phenomenon. Data were collected by face-to-face, in-depth, open-ended interviews. Data were analyzed using Open Code software (OPC 4.0) by following the steps of Colaizzi process. Results: The phenomenon that emerged out of the lived experiences of HNC women was "Personified as paragon of suffering.optimistic being of achieving normalcy," with five major themes and 13 subthemes. Conclusion: The conceptual model developed with the phenomenological approach is very specific to the women suffering from HNC, which will be contributing to develop strategies to improve the QOL of women. PMID:29440812

  16. Multiple methods for multiple futures: Integrating qualitative scenario planning and quantitative simulation modeling for natural resource decision making

    Science.gov (United States)

    Symstad, Amy J.; Fisichelli, Nicholas A.; Miller, Brian W.; Rowland, Erika; Schuurman, Gregor W.

    2017-01-01

    Scenario planning helps managers incorporate climate change into their natural resource decision making through a structured “what-if” process of identifying key uncertainties and potential impacts and responses. Although qualitative scenarios, in which ecosystem responses to climate change are derived via expert opinion, often suffice for managers to begin addressing climate change in their planning, this approach may face limits in resolving the responses of complex systems to altered climate conditions. In addition, this approach may fall short of the scientific credibility managers often require to take actions that differ from current practice. Quantitative simulation modeling of ecosystem response to climate conditions and management actions can provide this credibility, but its utility is limited unless the modeling addresses the most impactful and management-relevant uncertainties and incorporates realistic management actions. We use a case study to compare and contrast management implications derived from qualitative scenario narratives and from scenarios supported by quantitative simulations. We then describe an analytical framework that refines the case study’s integrated approach in order to improve applicability of results to management decisions. The case study illustrates the value of an integrated approach for identifying counterintuitive system dynamics, refining understanding of complex relationships, clarifying the magnitude and timing of changes, identifying and checking the validity of assumptions about resource responses to climate, and refining management directions. Our proposed analytical framework retains qualitative scenario planning as a core element because its participatory approach builds understanding for both managers and scientists, lays the groundwork to focus quantitative simulations on key system dynamics, and clarifies the challenges that subsequent decision making must address.

  17. Qualitative analysis in reliability and safety studies

    International Nuclear Information System (INIS)

    Worrell, R.B.; Burdick, G.R.

    1976-01-01

    The qualitative evaluation of system logic models is described as it pertains to assessing the reliability and safety characteristics of nuclear systems. Qualitative analysis of system logic models, i.e., models couched in an event (Boolean) algebra, is defined, and the advantages inherent in qualitative analysis are explained. Certain qualitative procedures that were developed as a part of fault-tree analysis are presented for illustration. Five fault-tree analysis computer-programs that contain a qualitative procedure for determining minimal cut sets are surveyed. For each program the minimal cut-set algorithm and limitations on its use are described. The recently developed common-cause analysis for studying the effect of common-causes of failure on system behavior is explained. This qualitative procedure does not require altering the fault tree, but does use minimal cut sets from the fault tree as part of its input. The method is applied using two different computer programs. 25 refs

  18. Mathematical models to describe iontophoretic transport in vitro and in vivo and the effect of current application on the skin barrier.

    Science.gov (United States)

    Gratieri, Taís; Kalia, Yogeshvar N

    2013-02-01

    more esoteric "constant phase element"; the latter provides a better mathematical description of the "non-ideal" behaviour of skin impedance. However, in addition to simply providing a "mathematical" fit of the observed data, it is essential to relate these circuit elements to biological structures present in the skin. More recently, attention has also turned to what happens when the permeant crosses the epidermis and reaches the systemic circulation and pharmacokinetic models have been proposed to interpret data from iontophoretic delivery studies in vivo. Here, we provide an overview of mathematical models that have been proposed to describe (i) the effect of current application on the skin and the implications for potential iontophoretic transport pathways, (ii) electrotransport kinetics and (iii) the fate of iontophoretically delivered drugs once they enter the systemic circulation. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Proposing a Qualitative Approach for Corporate Competitive Capability Modeling in High-Tech Business (Case study: Software Industry

    Directory of Open Access Journals (Sweden)

    Mahmoud Saremi Saremi

    2010-09-01

    Full Text Available The evolution of global business trend for ICT-based products in recent decades shows the intensive activity of pioneer developing countries to gain a powerful competitive position in global software industry. In this research, with regard to importance of competition issue for top managers of Iranian software companies, a conceptual model has been developed for Corporate Competitive Capability concept. First, after describing the research problem, we present a comparative review of recent theories of firm and competition that has been applied by different researchers in the High-Tech and Knowledge Intensive Organization filed. Afterwards, with a detailed review of literature and previous research papers, an initial research framework and applied research method has been proposed. The main and final section of paper assigned to describing the result of research in different steps of qualitative modeling process. The agreed concepts are related to corporate competitive capability, the elicited and analyzed experts Cause Map, the elicited collective causal maps, and the final proposed model for software industry are the modeling results for this paper.

  20. Qualitative models of magnetic field accelerated propagation in a plasma due to the Hall effect

    International Nuclear Information System (INIS)

    Kukushkin, A.B.; Cherepanov, K.V.

    2000-01-01

    Two qualitatively new models of accelerated magnetic field propagation (relative to normal diffusion) in a plasma due to the Hall effect are developed within the frames of the electron magnetic hydrodynamics. The first model is based on a simple hydrodynamic approach, which, in particular, reproduces the number of known theoretical results. The second one makes it possible to obtain exact analytical description of the basic characteristics of the magnetic field accelerated propagation in a inhomogeneous iso-thermic plasma, namely, the magnetic field front and its effective width [ru

  1. Qualitative and quantitative guidelines for the comparison of environmental model predictions

    International Nuclear Information System (INIS)

    Scott, M.

    1995-03-01

    The question of how to assess or compare predictions from a number of models is one of concern in the validation of models, in understanding the effects of different models and model parameterizations on model output, and ultimately in assessing model reliability. Comparison of model predictions with observed data is the basic tool of model validation while comparison of predictions amongst different models provides one measure of model credibility. The guidance provided here is intended to provide qualitative and quantitative approaches (including graphical and statistical techniques) to such comparisons for use within the BIOMOVS II project. It is hoped that others may find it useful. It contains little technical information on the actual methods but several references are provided for the interested reader. The guidelines are illustrated on data from the VAMP CB scenario. Unfortunately, these data do not permit all of the possible approaches to be demonstrated since predicted uncertainties were not provided. The questions considered are concerned with a) intercomparison of model predictions and b) comparison of model predictions with the observed data. A series of examples illustrating some of the different types of data structure and some possible analyses have been constructed. A bibliography of references on model validation is provided. It is important to note that the results of the various techniques discussed here, whether qualitative or quantitative, should not be considered in isolation. Overall model performance must also include an evaluation of model structure and formulation, i.e. conceptual model uncertainties, and results for performance measures must be interpreted in this context. Consider a number of models which are used to provide predictions of a number of quantities at a number of time points. In the case of the VAMP CB scenario, the results include predictions of total deposition of Cs-137 and time dependent concentrations in various

  2. Learning Qualitative Differential Equation models: a survey of algorithms and applications.

    Science.gov (United States)

    Pang, Wei; Coghill, George M

    2010-03-01

    Over the last two decades, qualitative reasoning (QR) has become an important domain in Artificial Intelligence. QDE (Qualitative Differential Equation) model learning (QML), as a branch of QR, has also received an increasing amount of attention; many systems have been proposed to solve various significant problems in this field. QML has been applied to a wide range of fields, including physics, biology and medical science. In this paper, we first identify the scope of this review by distinguishing QML from other QML systems, and then review all the noteworthy QML systems within this scope. The applications of QML in several application domains are also introduced briefly. Finally, the future directions of QML are explored from different perspectives.

  3. Qualitative models to predict impacts of human interventions in a wetland ecosystem

    Directory of Open Access Journals (Sweden)

    S. Loiselle

    2002-07-01

    Full Text Available The large shallow wetlands that dominate much of the South American continent are rich in biodiversity and complexity. Many of these undamaged ecosystems are presently being examined for their potential economic utility, putting pressure on local authorities and the conservation community to find ways of correctly utilising the available natural resources without compromising the ecosystem functioning and overall integrity. Contrary to many northern hemisphere ecosystems, there have been little long term ecological studies of these systems, leading to a lack of quantitative data on which to construct ecological or resource use models. As a result, decision makers, even well meaning ones, have difficulty in determining if particular economic activities can potentially cause significant damage to the ecosystem and how one should go about monitoring the impacts of such activities. While the direct impact of many activities is often known, the secondary indirect impacts are usually less clear and can depend on local ecological conditions.

    The use of qualitative models is a helpful tool to highlight potential feedback mechanisms and secondary effects of management action on ecosystem integrity. The harvesting of a single, apparently abundant, species can have indirect secondary effects on key trophic and abiotic compartments. In this paper, loop model analysis is used to qualitatively examine secondary effects of potential economic activities in a large wetland area in northeast Argentina, the Esteros del Ibera. Based on interaction with local actors together with observed ecological information, loop models were constructed to reflect relationships between biotic and abiotic compartments. A series of analyses were made to study the effect of different economic scenarios on key ecosystem compartments. Important impacts on key biotic compartments (phytoplankton, zooplankton, ichthyofauna, aquatic macrophytes and on the abiotic environment

  4. Qualitative models and experimental investigation of chaotic NOR gates and set/reset flip-flops

    Science.gov (United States)

    Rahman, Aminur; Jordan, Ian; Blackmore, Denis

    2018-01-01

    It has been observed through experiments and SPICE simulations that logical circuits based upon Chua's circuit exhibit complex dynamical behaviour. This behaviour can be used to design analogues of more complex logic families and some properties can be exploited for electronics applications. Some of these circuits have been modelled as systems of ordinary differential equations. However, as the number of components in newer circuits increases so does the complexity. This renders continuous dynamical systems models impractical and necessitates new modelling techniques. In recent years, some discrete dynamical models have been developed using various simplifying assumptions. To create a robust modelling framework for chaotic logical circuits, we developed both deterministic and stochastic discrete dynamical models, which exploit the natural recurrence behaviour, for two chaotic NOR gates and a chaotic set/reset flip-flop. This work presents a complete applied mathematical investigation of logical circuits. Experiments on our own designs of the above circuits are modelled and the models are rigorously analysed and simulated showing surprisingly close qualitative agreement with the experiments. Furthermore, the models are designed to accommodate dynamics of similarly designed circuits. This will allow researchers to develop ever more complex chaotic logical circuits with a simple modelling framework.

  5. Measurements of boat motion in waves at Durban harbour for qualitative validation of motion model

    CSIR Research Space (South Africa)

    Mosikare, OR

    2010-09-01

    Full Text Available in Waves at Durban Harbour for Qualitative Validation of Motion Model O.R. Mosikare1,2, N.J. Theron1, W. Van der Molen 1 University of Pretoria, South Africa, 0001 2Council for Scientific and Industrial Research, Meiring Naude Rd, Brummeria, 0001... stream_source_info Mosikare_2010.pdf.txt stream_content_type text/plain stream_size 3033 Content-Encoding UTF-8 stream_name Mosikare_2010.pdf.txt Content-Type text/plain; charset=UTF-8 Measurements of Boat Motion...

  6. Procedure to describe clavicular motion.

    Science.gov (United States)

    Gutierrez Delgado, Guivey; De Beule, Matthieu; Ortega Cardentey, Dolgis R; Segers, Patrick; Iznaga Benítez, Arsenio M; Rodríguez Moliner, Tania; Verhegghe, Benedict; Palmans, Tanneke; Van Hoof, Tom; Van Tongel, Alexander

    2017-03-01

    For many years, researchers have attempted to describe shoulder motions by using different mathematical methods. The aim of this study was to describe a procedure to quantify clavicular motion. The procedure proposed for the kinematic analysis consists of 4 main processes: 3 transcortical pins in the clavicle, motion capture, obtaining 3-dimensional bone models, and data processing. Clavicular motion by abduction (30° to 150°) and flexion (55° to 165°) were characterized by an increment of retraction of 27° to 33°, elevation of 25° to 28°, and posterior rotation of 14° to 15°, respectively. In circumduction, clavicular movement described an ellipse, which was reflected by retraction and elevation. Kinematic analysis shows that the articular surfaces move by simultaneously rolling and sliding on the convex surface of the sternum for the 3 movements of abduction, flexion, and circumduction. The use of 3 body landmarks in the clavicle and the direct measurement of bone allowed description of the osteokinematic and arthrokinematic movement of the clavicle. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  7. The effect of em>Hydrobia ulvaeem> and microphytobenthos on cohesive sediment dynamics on an intertidal mudflat described by means of numerical modelling

    DEFF Research Database (Denmark)

    Lumborg, Ulrik; Andersen, Thorbjørn Joest; Pejrup, Morten

    2006-01-01

    been used as input to the 2D hydrodynamic numerical model MIKE 21 MT. The model was used to investigate the effect that differences in the benthic communities may have on the net deposition. The model included computation of hydrodynamics, wave fields and cohesive sediment dynamics. Based...

  8. Qualitative Fault Isolation of Hybrid Systems: A Structural Model Decomposition-Based Approach

    Science.gov (United States)

    Bregon, Anibal; Daigle, Matthew; Roychoudhury, Indranil

    2016-01-01

    Quick and robust fault diagnosis is critical to ensuring safe operation of complex engineering systems. A large number of techniques are available to provide fault diagnosis in systems with continuous dynamics. However, many systems in aerospace and industrial environments are best represented as hybrid systems that consist of discrete behavioral modes, each with its own continuous dynamics. These hybrid dynamics make the on-line fault diagnosis task computationally more complex due to the large number of possible system modes and the existence of autonomous mode transitions. This paper presents a qualitative fault isolation framework for hybrid systems based on structural model decomposition. The fault isolation is performed by analyzing the qualitative information of the residual deviations. However, in hybrid systems this process becomes complex due to possible existence of observation delays, which can cause observed deviations to be inconsistent with the expected deviations for the current mode in the system. The great advantage of structural model decomposition is that (i) it allows to design residuals that respond to only a subset of the faults, and (ii) every time a mode change occurs, only a subset of the residuals will need to be reconfigured, thus reducing the complexity of the reasoning process for isolation purposes. To demonstrate and test the validity of our approach, we use an electric circuit simulation as the case study.

  9. Developing a change model for peer worker interventions in mental health services: a qualitative research study.

    Science.gov (United States)

    Gillard, S; Gibson, S L; Holley, J; Lucock, M

    2015-10-01

    A range of peer worker roles are being introduced into mental health services internationally. There is some evidence that attests to the benefits of peer workers for the people they support but formal trial evidence in inconclusive, in part because the change model underpinning peer support-based interventions is underdeveloped. Complex intervention evaluation guidance suggests that understandings of how an intervention is associated with change in outcomes should be modelled, theoretically and empirically, before the intervention can be robustly evaluated. This paper aims to model the change mechanisms underlying peer worker interventions. In a qualitative, comparative case study of ten peer worker initiatives in statutory and voluntary sector mental health services in England in-depth interviews were carried out with 71 peer workers, service users, staff and managers, exploring their experiences of peer working. Using a Grounded Theory approach we identified core processes within the peer worker role that were productive of change for service users supported by peer workers. Key change mechanisms were: (i) building trusting relationships based on shared lived experience; (ii) role-modelling individual recovery and living well with mental health problems; (iii) engaging service users with mental health services and the community. Mechanisms could be further explained by theoretical literature on role-modelling and relationship in mental health services. We were able to model process and downstream outcomes potentially associated with peer worker interventions. An empirically and theoretically grounded change model can be articulated that usefully informs the development, evaluation and planning of peer worker interventions.

  10. Qualitative Validation of the IMM Model for ISS and STS Programs

    Science.gov (United States)

    Kerstman, E.; Walton, M.; Reyes, D.; Boley, L.; Saile, L.; Young, M.; Arellano, J.; Garcia, Y.; Myers, J. G.

    2016-01-01

    To validate and further improve the Integrated Medical Model (IMM), medical event data were obtained from 32 ISS and 122 STS person-missions. Using the crew characteristics from these observed missions, IMM v4.0 was used to forecast medical events and medical resource utilization. The IMM medical condition incidence values were compared to the actual observed medical event incidence values, and the IMM forecasted medical resource utilization was compared to actual observed medical resource utilization. Qualitative comparisons of these parameters were conducted for both the ISS and STS programs. The results of these analyses will provide validation of IMM v4.0 and reveal areas of the model requiring adjustments to improve the overall accuracy of IMM outputs. This validation effort should result in enhanced credibility of the IMM and improved confidence in the use of IMM as a decision support tool for human space flight.

  11. Developments to the Sylvan stand structure model to describe wood quality changes in southern bottomland hardwood forests because of forest management

    Science.gov (United States)

    Ian R. Scott

    2009-01-01

    Growth models can produce a wealth of detailed information that is often very difficult to perceive because it is frequently presented either as summary tables, stand view or landscape view visualizations. We have developed new tools for use with the Sylvan model (Larsen 1994) that allow the analysis of wood-quality changes as a consequence of forest management....

  12. Sensitivity analysis of a radionuclide transfer model describing contaminated vegetation in Fukushima prefecture, using Morris and Sobol' - Application of sensitivity analysis on a radionuclides transfer model in the environment describing weeds contamination in Fukushima Prefecture, using Morris method and Sobol' indices indices

    Energy Technology Data Exchange (ETDEWEB)

    Nicoulaud-Gouin, V.; Metivier, J.M.; Gonze, M.A. [Institut de Radioprotection et de Surete Nucleaire-PRP-ENV/SERIS/LM2E (France); Garcia-Sanchez, L. [Institut de Radioprotection et de Surete Nucleaire-PRPENV/SERIS/L2BT (France)

    2014-07-01

    The increasing spatial and temporal complexity of models demands methods capable of ranking the influence of their large numbers of parameters. This question specifically arises in assessment studies on the consequences of the Fukushima accident. Sensitivity analysis aims at measuring the influence of input variability on the output response. Generally, two main approaches are distinguished (Saltelli, 2001, Iooss, 2011): - Screening approach, less expensive in computation time and allowing to identify non influential parameters; - Measures of importance, introducing finer quantitative indices. In this category, there are regression-based methods, assuming a linear or monotonic response (Pearson coefficient, Spearman coefficient), and variance-based methods, without assumptions on the model but requiring an increasingly prohibitive number of evaluations when the number of parameters increases. These approaches are available in various statistical programs (notably R) but are still poorly integrated in modelling platforms of radioecological risk assessment. This work aimed at illustrating the benefits of sensitivity analysis in the course of radioecological risk assessments This study used two complementary state-of-art global sensitivity analysis methods: - The screening method of Morris (Morris, 1991; Campolongo et al., 2007) based on limited model evaluations with a one-at-a-time (OAT) design; - The variance-based Sobol' sensitivity analysis (Saltelli, 2002) based a large number of model evaluations in the parameter space with a quasi-random sampling (Owen, 2003). Sensitivity analyses were applied on a dynamic Soil-Plant Deposition Model (Gonze et al., submitted to this conference) predicting foliar concentration in weeds after atmospheric radionuclide fallout. The Soil-Plant Deposition Model considers two foliage pools and a root pool, and describes foliar biomass growth with a Verhulst model. The developed semi-analytic formulation of foliar concentration

  13. Use of Game Theory to model patient engagement after surgery: a qualitative analysis.

    Science.gov (United States)

    Castellanos, Stephen A; Buentello, Gerardo; Gutierrez-Meza, Diana; Forgues, Angela; Haubert, Lisa; Artinyan, Avo; Macdonald, Cameron L; Suliburk, James W

    2018-01-01

    Patient engagement is challenging to define and operationalize. Qualitative analysis allows us to explore patient perspectives on this topic and establish themes. A game theoretic signaling model also provides a framework through which to further explore engagement. Over a 6-mo period, thirty-eight interviews were conducted within 6 wk of discharge in patients undergoing thyroid, parathyroid, or colorectal surgery. Interviews were transcribed, anonymized, and analyzed using the NVivo 11 platform. A signaling model was then developed depicting the doctor-patient interaction surrounding the patient's choice to reach out to their physician with postoperative concerns based upon the patient's perspective of the doctor's availability. This was defined as "engagement". We applied the model to the qualitative data to determine possible causations for a patient's engagement or lack thereof. A private hospital's and a safety net hospital's populations were contrasted. The private patient population was more likely to engage than their safety-net counterparts. Using our model in conjunction with patient data, we determined possible etiologies for this engagement to be due to the private patient's perceived probability of dealing with an available doctor and apparent signals from the doctor indicating so. For the safety-net population, decreased access to care caused them to be less willing to engage with a doctor perceived as possibly unavailable. A physician who understands these Game Theory concepts may be able to alter their interactions with their patients, tailoring responses and demeanor to fit the patient's circumstances and possible barriers to engagement. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. A comparison of Reduced Life Expectancy (RLE) model with Haber's Rule to describe effects of exposure time on toxicity

    International Nuclear Information System (INIS)

    Verma, Vibha; Yu, Qiming J.; Connell, Des W.

    2015-01-01

    The Reduced Life Expectancy (RLE) Model (LC 50  = [ln(NLE) – ln(LT 50 )]/d) has been proposed as an alternative to Haber's Rule. The model is based on a linear relationship between LC 50 (Lethal Exposure Concentration) and lnLT 50 (Lethal Exposure Time) and uses NLE (Normal Life Expectancy) as a limiting point as well as a long term data point (where d is a constant). The purposes of this paper were to compare the RLE Model with Haber's Rule with available toxicity data and to evaluate the strengths and weaknesses of each approach. When LT 50 is relatively short and LC 50 is high, Haber's Rule is consistent with the RLE model. But the difference between the two was evident in the situation when LT 50 is relatively long and LC 50 is low where the RLE model is a marked departure from Haber's Rule. The RLE Model can be used to appropriately evaluate long term effects of exposure. - Highlights: • The strength and weakness of Haber's Rule in relation to the RLE model is needed. • Haber's Rule now used universally is quite inappropriate for environmental toxicity. • Normal life expectancy, a new parameter l is used to evaluate effects of exposure time on toxicity. • According to RLE model when LC 50 approaches zero, then LT 50  = Normal Life Expectancy. • The RLE model can be used to evaluate long term effects of exposure-accurately and easily. - The RLE approach is a more appropriate alternative particularly to evaluate long term effects of exposure. It can be easily used to estimate long term effects of exposure

  15. Analysis of Water Conflicts across Natural and Societal Boundaries: Integration of Quantitative Modeling and Qualitative Reasoning

    Science.gov (United States)

    Gao, Y.; Balaram, P.; Islam, S.

    2009-12-01

    , the knowledge generated from these studies cannot be easily generalized or transferred to other basins. Here, we present an approach to integrate the quantitative and qualitative methods to study water issues and capture the contextual knowledge of water management- by combining the NSSs framework and an area of artificial intelligence called qualitative reasoning. Using the Apalachicola-Chattahoochee-Flint (ACF) River Basin dispute as an example, we demonstrate how quantitative modeling and qualitative reasoning can be integrated to examine the impact of over abstraction of water from the river on the ecosystem and the role of governance in shaping the evolution of the ACF water dispute.

  16. A new predictive dynamic model describing the effect of the ambient temperature and the convective heat transfer coefficient on bacterial growth.

    Science.gov (United States)

    Ben Yaghlene, H; Leguerinel, I; Hamdi, M; Mafart, P

    2009-07-31

    In this study, predictive microbiology and food engineering were combined in order to develop a new analytical model predicting the bacterial growth under dynamic temperature conditions. The proposed model associates a simplified primary bacterial growth model without lag, the secondary Ratkowsky "square root" model and a simplified two-parameter heat transfer model regarding an infinite slab. The model takes into consideration the product thickness, its thermal properties, the ambient air temperature, the convective heat transfer coefficient and the growth parameters of the micro organism of concern. For the validation of the overall model, five different combinations of ambient air temperature (ranging from 8 degrees C to 12 degrees C), product thickness (ranging from 1 cm to 6 cm) and convective heat transfer coefficient (ranging from 8 W/(m(2) K) to 60 W/(m(2) K)) were tested during a cooling procedure. Moreover, three different ambient air temperature scenarios assuming alternated cooling and heating stages, drawn from real refrigerated food processes, were tested. General agreement between predicted and observed bacterial growth was obtained and less than 5% of the experimental data fell outside the 95% confidence bands estimated by the bootstrap percentile method, at all the tested conditions. Accordingly, the overall model was successfully validated for isothermal and dynamic refrigeration cycles allowing for temperature dynamic changes at the centre and at the surface of the product. The major impact of the convective heat transfer coefficient and the product thickness on bacterial growth during the product cooling was demonstrated. For instance, the time needed for the same level of bacterial growth to be reached at the product's half thickness was estimated to be 5 and 16.5 h at low and high convection level, respectively. Moreover, simulation results demonstrated that the predicted bacterial growth at the air ambient temperature cannot be assumed to be

  17. Experimental and numerical investigations to describe the failure behaviour of steels of different toughness by means of damage models. Final report

    International Nuclear Information System (INIS)

    Kussmaul, K.; Seidenfuss, M.; Elsaesser, K.; Mayer, U.; Zies, G.

    1995-08-01

    Within the scope of the project the applicability of local approach models to different steels in reactor technology was investigated. To this two ferritic and one austenitic material were investigated. The metallographic investigations carried out in this project prove the fact that the fracture development of the three investigated materials can be divided in three phases: Void initiation, void growth, and void coalescence. The focus of the research project was to determine the parameters required for the local approach models if possible with the help of metallographic investigations. In order to obtain quantitative results with realistic expenditure an automatic imagine evaluation system was adapted. In the course of the project it could be found that two out of the maximum six damage parameters of the Rousselier model were constant for all three materials. There is an indication that these two parameters are independent of the material and can generally be assumed as constant. The investigations have proved that the selected local approach models are adequate for calculating the failure behaviour of smooth, notched and precracked specimens under static load. The parameters required for the damage models are independent of geometry and size, and so a transferability of the parameters is possible. (orig./MM) [de

  18. A fuzzy-logic-based approach to qualitative safety modelling for marine systems

    International Nuclear Information System (INIS)

    Sii, H.S.; Ruxton, Tom; Wang Jin

    2001-01-01

    Safety assessment based on conventional tools (e.g. probability risk assessment (PRA)) may not be well suited for dealing with systems having a high level of uncertainty, particularly in the feasibility and concept design stages of a maritime or offshore system. By contrast, a safety model using fuzzy logic approach employing fuzzy IF-THEN rules can model the qualitative aspects of human knowledge and reasoning processes without employing precise quantitative analyses. A fuzzy-logic-based approach may be more appropriately used to carry out risk analysis in the initial design stages. This provides a tool for working directly with the linguistic terms commonly used in carrying out safety assessment. This research focuses on the development and representation of linguistic variables to model risk levels subjectively. These variables are then quantified using fuzzy sets. In this paper, the development of a safety model using fuzzy logic approach for modelling various design variables for maritime and offshore safety based decision making in the concept design stage is presented. An example is used to illustrate the proposed approach

  19. Being reflexive in qualitative grounded theory: discussion and application of a model of reflexivity.

    Science.gov (United States)

    Engward, Hilary; Davis, Geraldine

    2015-07-01

    A discussion of the meaning of reflexivity in research with the presentation of examples of how a model of reflexivity was used in a grounded theory research project. Reflexivity requires the researcher to make transparent the decisions they make in the research process and is therefore important in developing quality in nursing research. The importance of being reflexive is highlighted in the literature in relation to nursing research, however, practical guidance as to how to go about doing research reflexively is not always clearly articulated. This is a discussion paper. The concept of reflexivity in research is explored using the Alvesson and Skoldberg model of reflexivity and practical examples of how a researcher developed reflexivity in a grounded theory project are presented. Nurse researchers are encouraged to explore and apply the concept of reflexivity in their research practices to develop transparency in the research process and to increase robustness in their research. The Alvesson and Skoldberg model is of value in applying reflexivity in qualitative nursing research, particularly in grounded theory research. Being reflexive requires the researcher to be completely open about decisions that are made in the research process. The Alvesson and Skolberg model of reflexivity is a useful model that can enhance reflexivity in the research process. It can be a useful practical tool to develop reflexivity in grounded theory research. © 2015 John Wiley & Sons Ltd.

  20. Discrete event simulation tool for analysis of qualitative models of continuous processing systems

    Science.gov (United States)

    Malin, Jane T. (Inventor); Basham, Bryan D. (Inventor); Harris, Richard A. (Inventor)

    1990-01-01

    An artificial intelligence design and qualitative modeling tool is disclosed for creating computer models and simulating continuous activities, functions, and/or behavior using developed discrete event techniques. Conveniently, the tool is organized in four modules: library design module, model construction module, simulation module, and experimentation and analysis. The library design module supports the building of library knowledge including component classes and elements pertinent to a particular domain of continuous activities, functions, and behavior being modeled. The continuous behavior is defined discretely with respect to invocation statements, effect statements, and time delays. The functionality of the components is defined in terms of variable cluster instances, independent processes, and modes, further defined in terms of mode transition processes and mode dependent processes. Model construction utilizes the hierarchy of libraries and connects them with appropriate relations. The simulation executes a specialized initialization routine and executes events in a manner that includes selective inherency of characteristics through a time and event schema until the event queue in the simulator is emptied. The experimentation and analysis module supports analysis through the generation of appropriate log files and graphics developments and includes the ability of log file comparisons.

  1. Describing Compton scattering and two-quanta positron annihilation based on Compton profiles: Two models suited for the Monte Carlo method

    CERN Document Server

    Bohlen, TT; Patera, V; Sala, P R

    2012-01-01

    An accurate description of the basic physics processes of Compton scattering and positron annihilation in matter requires the consideration of atomic shell structure effects and, in specific, the momentum distributions of the atomic electrons. Two algorithms which model Compton scattering and two-quanta positron annihilation at rest accounting for shell structure effects are proposed. Two-quanta positron annihilation is a physics process which is of particular importance for applications such as positron emission tomography (PET). Both models use a detailed description of the processes which incorporate consistently Doppler broadening and binding effects. This together with the relatively low level of complexity of the models makes them particularly suited to be employed by fast sampling methods for Monte Carlo particle transport. Momentum distributions of shell electrons are obtained from parametrized one-electron Compton profiles. For conduction electrons, momentum distributions are derived in the framework...

  2. A model to describe the surface gradient-nanograin formation and property of friction stir processed laser Co-Cr-Ni-Mo alloy

    Science.gov (United States)

    Li, Ruidi; Yuan, Tiechui; Qiu, Zili

    2014-07-01

    A gradient-nanograin surface layer of Co-base alloy was prepared by friction stir processing (FSP) of laser-clad coating in this work. However, it is lack of a quantitatively function relationship between grain refinement and FSP conditions. Based on this, an analytic model is derived for the correlations between carbide size, hardness and rotary speed, layer depth during in-situ FSP of laser-clad Co-Cr-Ni-Mo alloy. The model is based on the principle of typical plastic flow in friction welding and dynamic recrystallization. The FSP experiment for modification of laser-clad Co-based alloy was conducted and its gradient nanograin and hardness were characterized. It shows that the model is consistent with experimental results.

  3. Linear mixed-effects models to describe length-weight relationships for yellow croaker (Larimichthys Polyactis) along the north coast of China.

    Science.gov (United States)

    Ma, Qiuyun; Jiao, Yan; Ren, Yiping

    2017-01-01

    In this study, length-weight relationships and relative condition factors were analyzed for Yellow Croaker (Larimichthys polyactis) along the north coast of China. Data covered six regions from north to south: Yellow River Estuary, Coastal Waters of Northern Shandong, Jiaozhou Bay, Coastal Waters of Qingdao, Haizhou Bay, and South Yellow Sea. In total 3,275 individuals were collected during six years (2008, 2011-2015). One generalized linear model, two simply linear models and nine linear mixed effect models that applied the effects from regions and/or years to coefficient a and/or the exponent b were studied and compared. Among these twelve models, the linear mixed effect model with random effects from both regions and years fit the data best, with lowest Akaike information criterion value and mean absolute error. In this model, the estimated a was 0.0192, with 95% confidence interval 0.0178~0.0308, and the estimated exponent b was 2.917 with 95% confidence interval 2.731~2.945. Estimates for a and b with the random effects in intercept and coefficient from Region and Year, ranged from 0.013 to 0.023 and from 2.835 to 3.017, respectively. Both regions and years had effects on parameters a and b, while the effects from years were shown to be much larger than those from regions. Except for Coastal Waters of Northern Shandong, a decreased from north to south. Condition factors relative to reference years of 1960, 1986, 2005, 2007, 2008~2009 and 2010 revealed that the body shape of Yellow Croaker became thinner in recent years. Furthermore relative condition factors varied among months, years, regions and length. The values of a and relative condition factors decreased, when the environmental pollution became worse, therefore, length-weight relationships could be an indicator for the environment quality. Results from this study provided basic description of current condition of Yellow Croaker along the north coast of China.

  4. A model of the FAD redox cycle describes the dynamics of the effect of the geomagnetic field on the human visual system.

    Science.gov (United States)

    Thoss, Franz; Bartsch, Bengt

    2017-12-01

    In experimental studies, we could show that the visual threshold of man is influenced by the geomagnetic field. One of the results was that the threshold shows periodic fluctuations when the vertical component of the field is reversed periodically. The maximum of these oscillations occurred at a period duration of 110 s. To explain this phenomenon, we chose the process that likely underlies the navigation of birds in the geomagnetic field: the light reaction of the FAD component of cryptochrome in the retina. The human retina contains cryptpochrome like the bird retina. Based on the investigations of Müller and Ahmad (J Biol Chem 286:21033-21040, 2011) and Solov'yov and Schulten (J Phys Chem B 116:1089-1099, 2012), we designed a model of the light-induced reduction and subsequent reoxidation of FAD. This model contains a radical pair, whose interconversion dynamics are affected by the geomagnetic field. The parameters of the model were partly calculated from the data of our experimental investigation and partly taken from the results of other authors. These parameters were then optimized by adjusting the model behaviour to the experimental results. The simulation of the finished model shows that the concentrations of all substances included show really oscillations with the frequency of the modelled magnetic field. After optimization of the parameters, the oscillations of FAD and FADH* show maximal amplitude at a period duration of 110 s, as was observed in the experiment. This makes it most likely that the signal, which influences the visual system, originates from FADH* (signalling state).

  5. Qualitative and quantitative examination of the performance of regional air quality models representing different modeling approaches

    International Nuclear Information System (INIS)

    Bhumralkar, C.M.; Ludwig, F.L.; Shannon, J.D.; McNaughton, D.

    1985-04-01

    The calculations of three different air quality models were compared with the best available observations. The comparisons were made without calibrating the models to improve agreement with the observations. Model performance was poor for short averaging times (less than 24 hours). Some of the poor performance can be traced to errors in the input meteorological fields, but error exist on all levels. It should be noted that these models were not originally designed for treating short-term episodes. For short-term episodes, much of the variance in the data can arise from small spatial scale features that tend to be averaged out over longer periods. These small spatial scale features cannot be resolved with the coarse grids that are used for the meteorological and emissions inputs. Thus, it is not surprising that the models performed for the longer averaging times. The models compared were RTM-II, ENAMAP-2 and ACID. (17 refs., 5 figs., 4 tabs

  6. Model-Based Analysis for Qualitative Data: An Application in Drosophila Germline Stem Cell Regulation

    Science.gov (United States)

    Pargett, Michael; Rundell, Ann E.; Buzzard, Gregery T.; Umulis, David M.

    2014-01-01

    Discovery in developmental biology is often driven by intuition that relies on the integration of multiple types of data such as fluorescent images, phenotypes, and the outcomes of biochemical assays. Mathematical modeling helps elucidate the biological mechanisms at play as the networks become increasingly large and complex. However, the available data is frequently under-utilized due to incompatibility with quantitative model tuning techniques. This is the case for stem cell regulation mechanisms explored in the Drosophila germarium through fluorescent immunohistochemistry. To enable better integration of biological data with modeling in this and similar situations, we have developed a general parameter estimation process to quantitatively optimize models with qualitative data. The process employs a modified version of the Optimal Scaling method from social and behavioral sciences, and multi-objective optimization to evaluate the trade-off between fitting different datasets (e.g. wild type vs. mutant). Using only published imaging data in the germarium, we first evaluated support for a published intracellular regulatory network by considering alternative connections of the same regulatory players. Simply screening networks against wild type data identified hundreds of feasible alternatives. Of these, five parsimonious variants were found and compared by multi-objective analysis including mutant data and dynamic constraints. With these data, the current model is supported over the alternatives, but support for a biochemically observed feedback element is weak (i.e. these data do not measure the feedback effect well). When also comparing new hypothetical models, the available data do not discriminate. To begin addressing the limitations in data, we performed a model-based experiment design and provide recommendations for experiments to refine model parameters and discriminate increasingly complex hypotheses. PMID:24626201

  7. Qualitative and Computational Analysis of a Mathematical Model for Tumor-Immune Interactions

    Directory of Open Access Journals (Sweden)

    F. A. Rihan

    2012-01-01

    Full Text Available We provide a family of ordinary and delay differential equations to model the dynamics of tumor-growth and immunotherapy interactions. We explore the effects of adoptive cellular immunotherapy on the model and describe under what circumstances the tumor can be eliminated. The possibility of clearing the tumor, with a strategy, is based on two parameters in the model: the rate of influx of the effector cells and the rate of influx of IL-2. The critical tumor-growth rate, below which endemic tumor does not exist, has been found. One can use the model to make predictions about tumor dormancy.

  8. A method to identify energy efficiency measures for factory systems based on qualitative modeling

    CERN Document Server

    Krones, Manuela

    2017-01-01

    Manuela Krones develops a method that supports factory planners in generating energy-efficient planning solutions. The method provides qualitative description concepts for factory planning tasks and energy efficiency knowledge as well as an algorithm-based linkage between these measures and the respective planning tasks. Its application is guided by a procedure model which allows a general applicability in the manufacturing sector. The results contain energy efficiency measures that are suitable for a specific planning task and reveal the roles of various actors for the measures’ implementation. Contents Driving Concerns for and Barriers against Energy Efficiency Approaches to Increase Energy Efficiency in Factories Socio-Technical Description of Factory Planning Tasks Description of Energy Efficiency Measures Case Studies on Welding Processes and Logistics Systems Target Groups Lecturers and Students of Industrial Engineering, Production Engineering, Environmental Engineering, Mechanical Engineering Practi...

  9. Applying the chronic care model to an employee benefits program: a qualitative inquiry.

    Science.gov (United States)

    Schauer, Gillian L; Wilson, Mark; Barrett, Barbara; Honeycutt, Sally; Hermstad, April K; Kegler, Michelle C

    2013-12-01

    To assess how employee benefits programs may strengthen and/or complement elements of the chronic care model (CCM), a framework used by health systems to improve chronic illness care. A qualitative inquiry consisting of semi-structured interviews with employee benefit administrators and partners from a self-insured, self-administered employee health benefits program was conducted at a large family-owned business in southwest Georgia. Results indicate that the employer adapted and used many health system-related elements of the CCM in the design of their benefit program. Data also suggest that the employee benefits program contributed to self-management skills and to informing and activating patients to interact with the health system. Findings suggest that employee benefits programs can use aspects of the CCM in their own benefit design, and can structure their benefits to contribute to patient-related elements from the CCM.

  10. Exhaustive Classification of the Invariant Solutions for a Specific Nonlinear Model Describing Near Planar and Marginally Long-Wave Unstable Interfaces for Phase Transition

    Science.gov (United States)

    Ahangari, Fatemeh

    2018-05-01

    Problems of thermodynamic phase transition originate inherently in solidification, combustion and various other significant fields. If the transition region among two locally stable phases is adequately narrow, the dynamics can be modeled by an interface motion. This paper is devoted to exhaustive analysis of the invariant solutions for a modified Kuramoto-Sivashinsky equation in two spatial and one temporal dimensions is presented. This nonlinear partial differential equation asymptotically characterizes near planar interfaces, which are marginally long-wave unstable. For this purpose, by applying the classical symmetry method for this model the classical symmetry operators are attained. Moreover, the structure of the Lie algebra of symmetries is discussed and the optimal system of subalgebras, which yields the preliminary classification of group invariant solutions is constructed. Mainly, the Lie invariants corresponding to the infinitesimal symmetry generators as well as associated similarity reduced equations are also pointed out. Furthermore, the nonclassical symmetries of this nonlinear PDE are also comprehensively investigated.

  11. An Early Model for Value and Sustainability in Health Information Exchanges: Qualitative Study

    Science.gov (United States)

    2018-01-01

    Background The primary value relative to health information exchange has been seen in terms of cost savings relative to laboratory and radiology testing, emergency department expenditures, and admissions. However, models are needed to statistically quantify value and sustainability and better understand the dependent and mediating factors that contribute to value and sustainability. Objective The purpose of this study was to provide a basis for early model development for health information exchange value and sustainability. Methods A qualitative study was conducted with 21 interviews of eHealth Exchange participants across 10 organizations. Using a grounded theory approach and 3.0 as a relative frequency threshold, 5 main categories and 16 subcategories emerged. Results This study identifies 3 core current perceived value factors and 5 potential perceived value factors—how interviewees predict health information exchanges may evolve as there are more participants. These value factors were used as the foundation for early model development for sustainability of health information exchange. Conclusions Using the value factors from the interviews, the study provides the basis for early model development for health information exchange value and sustainability. This basis includes factors from the research: fostering consumer engagement; establishing a provider directory; quantifying use, cost, and clinical outcomes; ensuring data integrity through patient matching; and increasing awareness, usefulness, interoperability, and sustainability of eHealth Exchange. PMID:29712623

  12. Autobiography and Anorexia: A Qualitative Alternative to Prochaska and DiClemente's Stages of Change Model

    Directory of Open Access Journals (Sweden)

    Félix Díaz

    2012-11-01

    Full Text Available In this article, we propose a qualitative approach to the study of the ways in which people face good and poor health issues. During the last 30 years, Prochaska and DiClemente's "trans-theoretical model" (1982, 1983, 1984, 1986, 1992 has gained relevance as a model to assess disposition for change in patients. We revise the features of the model and its common techniques to assess stages of change, underlining its methodological and conceptual problems. Particularly, we discuss the paradoxes set by "pre-contemplation" as a concept; the exogenous definition of human problems in terms of institutional and clinical criteria; and the ambiguity of the model, where the purpose of accompanying and orienting the patient contrasts with the imposition of problem definitions and solution strategies. We propose a narrative analysis of autobiographies of patients as an alternative that recasts their own notions of "change," "problem," and "vital trajectory." We illustrate this possibility with the analysis of an autobiographic interview with a woman who has a history of anorexia. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs1203209

  13. An Early Model for Value and Sustainability in Health Information Exchanges: Qualitative Study.

    Science.gov (United States)

    Feldman, Sue S

    2018-04-30

    The primary value relative to health information exchange has been seen in terms of cost savings relative to laboratory and radiology testing, emergency department expenditures, and admissions. However, models are needed to statistically quantify value and sustainability and better understand the dependent and mediating factors that contribute to value and sustainability. The purpose of this study was to provide a basis for early model development for health information exchange value and sustainability. A qualitative study was conducted with 21 interviews of eHealth Exchange participants across 10 organizations. Using a grounded theory approach and 3.0 as a relative frequency threshold, 5 main categories and 16 subcategories emerged. This study identifies 3 core current perceived value factors and 5 potential perceived value factors-how interviewees predict health information exchanges may evolve as there are more participants. These value factors were used as the foundation for early model development for sustainability of health information exchange. Using the value factors from the interviews, the study provides the basis for early model development for health information exchange value and sustainability. This basis includes factors from the research: fostering consumer engagement; establishing a provider directory; quantifying use, cost, and clinical outcomes; ensuring data integrity through patient matching; and increasing awareness, usefulness, interoperability, and sustainability of eHealth Exchange. ©Sue S Feldman. Originally published in JMIR Medical Informatics (http://medinform.jmir.org), 30.04.2018.

  14. Fault Tree Analysis with Temporal Gates and Model Checking Technique for Qualitative System Safety Analysis

    International Nuclear Information System (INIS)

    Koh, Kwang Yong; Seong, Poong Hyun

    2010-01-01

    Fault tree analysis (FTA) has suffered from several drawbacks such that it uses only static gates and hence can not capture dynamic behaviors of the complex system precisely, and it is in lack of rigorous semantics, and reasoning process which is to check whether basic events really cause top events is done manually and hence very labor-intensive and time-consuming for the complex systems while it has been one of the most widely used safety analysis technique in nuclear industry. Although several attempts have been made to overcome this problem, they can not still do absolute or actual time modeling because they adapt relative time concept and can capture only sequential behaviors of the system. In this work, to resolve the problems, FTA and model checking are integrated to provide formal, automated and qualitative assistance to informal and/or quantitative safety analysis. Our approach proposes to build a formal model of the system together with fault trees. We introduce several temporal gates based on timed computational tree logic (TCTL) to capture absolute time behaviors of the system and to give concrete semantics to fault tree gates to reduce errors during the analysis, and use model checking technique to automate the reasoning process of FTA

  15. Global energy supply the day before yesterday, the day after tomorrow, today, tomorrow - a qualitative modeling approach

    International Nuclear Information System (INIS)

    Herrmann, D.

    2004-01-01

    Current developments, and peak world market price levels, of oil, which add to the prices also of natural gas and other energy resources, give rise to the question whether there is any reason to expect fundamental changes and trend reversals in energy prices and on energy markets on a medium to long term basis. Attempts to find answers to such questions about the future can be helped by looking back into the more than three hundred years of global history of the development of modern industrial-sale power supply. Over that period of time, there have always been changes of boundary conditions and reversals of trends, respectively; step by step, by trial and error, a structural change has evolved from the use mainly of renewable energy resources to the primary use of fossil fuels supplemented by nuclear power. A model is presented which is able not only to describe and explain in a consistent and plausible way the global qualitative development of industrial-scale energy supply over the three different development periods, as far as contents go, between 1700 and 2100, but also allows higher resolution to be achieved in terms both of contents and time. The modeling approach is applied to the entire era of energy supply on an industrial scale, and should be seen as a representation of the specific perspective in this approach for further discussion. (orig.)

  16. Experimental Verification of a New Model Describing the Influence of Incomplete Signal Extinction Ratio on the Sensitivity Degradation due to Multiple Interferometric Crosstalk

    DEFF Research Database (Denmark)

    Liu, Fenghai; Rasmussen, Christian Jørgen; Pedersen, Rune Johan Skullerud

    1999-01-01

    Larger optical penalties than predicted by a Gaussian crosstalk model are found both in our experiments and in the literature when investigating signals including multiple interferometric crosstalk contributions. We attribute this to an imperfect signal extinction ratio. In this letter, simple...... analytical relations for crosstalk induced power penalties are derived taking the signal extinction ratio into account and excellent agreement with 10-Gb/s experiments is obtained. Both theory and experiment show the importance of the signal extinction ratio in connection with interferometric crosstalk....

  17. Is the fluid mosaic (and the accompanying raft hypothesis a suitable model to describe fundamental features of biological membranes? What may be missing?

    Directory of Open Access Journals (Sweden)

    Luis Alberto Bagatolli

    2013-11-01

    Full Text Available The structure, dynamics, and stability of lipid bilayers are controlled by thermodynamic forces, leading to overall tensionless membranes with a distinct lateral organization and a conspicuous lateral pressure profile. Bilayers are also subject to built-in curvature-stress instabilities that may be released locally or globally in terms of morphological changes leading to the formation of non-lamellar and curved structures. A key controller of the bilayer’s propensity to form curved structures is the average molecular shape of the different lipid molecules. Via the curvature stress, molecular shape mediates a coupling to membrane-protein function and provides a set of physical mechanisms for formation of lipid domains and laterally differentiated regions in the plane of the membrane. Unfortunately, these relevant physical features of membranes are often ignored in the most popular models for biological membranes. Results from a number of experimental and theoretical studies emphasize the significance of these fundamental physical properties and call for a refinement of the fluid mosaic model (and the accompanying raft hypothesis.

  18. Genistein, a general kinase inhibitor, as a potential antiviral for arenaviral hemorrhagic fever as described in the Pirital virus-Syrian golden hamster model.

    Science.gov (United States)

    Vela, Eric M; Knostman, Katherine A; Mott, Jason M; Warren, Richard L; Garver, Jennifer N; Vela, Lela Johnson; Stammen, Rachelle L

    2010-09-01

    Arenaviruses are rodent-borne negative strand RNA viruses and infection of these viruses in humans may result in disease and hemorrhagic fever. To date, supportive care, ribavirin, and in some cases immune plasma remain the foremost treatment options for arenaviral hemorrhagic fever. Research with the hemorrhagic fever causing-arenaviruses usually requires a Biosafety level (BSL)-4 environment; however, surrogate animal model systems have been developed to preliminarily study and screen various vaccines and antivirals. The Syrian golden hamster-Pirital virus (PIRV) surrogate model of hemorrhagic fever provides an opportunity to test new antivirals in an ABSL-3 setting. Thus, we challenged hamsters, implanted with telemetry, with PIRV and observed viremia and tissue viral titers, and changes in core body temperature, hematology, clinical chemistry, and coagulation parameters. Physical signs of disease of the PIRV-infected hamsters included weight loss, lethargy, petechial rashes, epistaxis, ocular orbital and rectal hemorrhage, and visible signs of neurologic disorders. However, treating animals with genistein, a plant derived isoflavone and general kinase inhibitor, resulted in increased survival rates and led to an improved clinical profile. In all, the results from this study demonstrate the potential of a general kinase inhibitor genistein as an antiviral against arenaviral hemorrhagic fever. 2010 Elsevier B.V. All rights reserved.

  19. A qualitative assessment of a community antiretroviral therapy group model in Tete, Mozambique.

    Directory of Open Access Journals (Sweden)

    Freya Rasschaert

    Full Text Available BACKGROUND: To improve retention on ART, Médecins Sans Frontières, the Ministry of Health and patients piloted a community-based antiretroviral distribution and adherence monitoring model through Community ART Groups (CAG in Tete, Mozambique. By December 2012, almost 6000 patients on ART had formed groups of whom 95.7% were retained in care. We conducted a qualitative study to evaluate the relevance, dynamic and impact of the CAG model on patients, their communities and the healthcare system. METHODS: Between October 2011 and May 2012, we conducted 16 focus group discussions and 24 in-depth interviews with the major stakeholders involved in the CAG model. Audio-recorded data were transcribed verbatim and analysed using a grounded theory approach. RESULTS: Six key themes emerged from the data: 1 Barriers to access HIV care, 2 CAG functioning and actors involved, 3 Benefits for CAG members, 4 Impacts of CAG beyond the group members, 5 Setbacks, and 6 Acceptance and future expectations of the CAG model. The model provides cost and time savings, certainty of ART access and mutual peer support resulting in better adherence to treatment. Through the active role of patients, HIV information could be conveyed to the broader community, leading to an increased uptake of services and positive transformation of the identity of people living with HIV. Potential pitfalls included limited access to CAG for those most vulnerable to defaulting, some inequity to patients in individual ART care and a high dependency on counsellors. CONCLUSION: The CAG model resulted in active patient involvement and empowerment, and the creation of a supportive environment improving the ART retention. It also sparked a reorientation of healthcare services towards the community and strengthened community actions. Successful implementation and scalability requires (a the acceptance of patients as partners in health, (b adequate resources, and (c a well-functioning monitoring and

  20. Assessing parameter importance of the Common Land Model based on qualitative and quantitative sensitivity analysis

    Directory of Open Access Journals (Sweden)

    J. Li

    2013-08-01

    Full Text Available Proper specification of model parameters is critical to the performance of land surface models (LSMs. Due to high dimensionality and parameter interaction, estimating parameters of an LSM is a challenging task. Sensitivity analysis (SA is a tool that can screen out the most influential parameters on model outputs. In this study, we conducted parameter screening for six output fluxes for the Common Land Model: sensible heat, latent heat, upward longwave radiation, net radiation, soil temperature and soil moisture. A total of 40 adjustable parameters were considered. Five qualitative SA methods, including local, sum-of-trees, multivariate adaptive regression splines, delta test and Morris methods, were compared. The proper sampling design and sufficient sample size necessary to effectively screen out the sensitive parameters were examined. We found that there are 2–8 sensitive parameters, depending on the output type, and about 400 samples are adequate to reliably identify the most sensitive parameters. We also employed a revised Sobol' sensitivity method to quantify the importance of all parameters. The total effects of the parameters were used to assess the contribution of each parameter to the total variances of the model outputs. The results confirmed that global SA methods can generally identify the most sensitive parameters effectively, while local SA methods result in type I errors (i.e., sensitive parameters labeled as insensitive or type II errors (i.e., insensitive parameters labeled as sensitive. Finally, we evaluated and confirmed the screening results for their consistency with the physical interpretation of the model parameters.

  1. Comparing Reasons for Quitting Substance Abuse with the Constructs of Behavioral Models: A Qualitative Study

    Directory of Open Access Journals (Sweden)

    Hamid Tavakoli Ghouchani

    2015-03-01

    Full Text Available Background and Objectives: The world population has reached over seven billion people. Of these, 230 million individuals abuse substances. Therefore, substance abuse prevention and treatment programs have received increasing attention during the past two decades. Understanding people’s motivations for quitting drug abuse is essential to the success of treatment. This study hence sought to identify major motivations for quitting and to compare them with the constructs of health education models. Materials and Methods: In the present study, qualitative content analysis was used to determine the main motivations for quitting substance abuse. Overall, 22 patients, physicians, and psychotherapists were selected from several addiction treatment clinics in Bojnord (Iran during 2014. Purposeful sampling method was applied and continued until data saturation was achieved. Data were collected through semi-structured, face-to-face interviews and field notes. All interviews were recorded and transcribed. Results: Content analysis revealed 33 sub-categories and nine categories including economic problems, drug-related concerns, individual problems, family and social problems, family expectations, attention to social status, beliefs about drug addiction, and valuing the quitting behavior. Accordingly, four themes, i.e. perceived threat, perceived barriers, attitude toward the behavior, and subjective norms, were extracted. Conclusion: Reasons for quitting substance abuse match the constructs of different behavioral models (e.g. the health belief model and the theory of planned behavior.

  2. Nursing students' perceptions of a collaborative clinical placement model: A qualitative descriptive study.

    Science.gov (United States)

    van der Riet, Pamela; Levett-Jones, Tracy; Courtney-Pratt, Helen

    2018-03-01

    Clinical placements are specifically designed to facilitate authentic learning opportunities and are an integral component of undergraduate nursing programs. However, as academics and clinicians frequently point out, clinical placements are fraught with problems that are long-standing and multidimensional in nature. Collaborative placement models, grounded in a tripartite relationship between students, university staff and clinical partners, and designed to foster students' sense of belonging, have recently been implemented to address many of the challenges associated with clinical placements. In this study a qualitative descriptive design was undertaken with the aim of exploring 14 third year third year nursing students' perceptions of a collaborative clinical placement model undertaken in an Australian university. Students participated in audio recorded focus groups following their final clinical placement. Thematic analysis of the interview data resulted in identification of six main themes: Convenience and Camaraderie, Familiarity and Confidence, Welcomed and Wanted, Belongingness and Support, Employment, and The Need for Broader Clinical Experiences. The clinical collaborative model fostered a sense of familiarity for many of the participants and this led to belongingness, acceptance, confidence and meaningful learning experiences. Copyright © 2018 Elsevier Ltd. All rights reserved.

  3. Describing and analysing primary health care system support for chronic illness care in Indigenous communities in Australia's Northern Territory – use of the Chronic Care Model

    Directory of Open Access Journals (Sweden)

    Stewart Allison

    2008-05-01

    Full Text Available Abstract Background Indigenous Australians experience disproportionately high prevalence of, and morbidity and mortality from chronic illness such as diabetes, renal disease and cardiovascular disease. Improving the understanding of how Indigenous primary care systems are organised to deliver chronic illness care will inform efforts to improve the quality of care for Indigenous people. Methods This cross-sectional study was conducted in 12 Indigenous communities in Australia's Northern Territory. Using the Chronic Care Model as a framework, we carried out a mail-out survey to collect information on material, financial and human resources relating to chronic illness care in participating health centres. Follow up face-to-face interviews with health centre staff were conducted to identify successes and difficulties in the systems in relation to providing chronic illness care to community members. Results Participating health centres had distinct areas of strength and weakness in each component of systems: 1 organisational influence – strengthened by inclusion of chronic illness goals in business plans, appointment of designated chronic disease coordinators and introduction of external clinical audits, but weakened by lack of training in disease prevention and health promotion and limited access to Medicare funding; 2 community linkages – facilitated by working together with community organisations (e.g. local stores and running community-based programs (e.g. "health week", but detracted by a shortage of staff especially of Aboriginal health workers working in the community; 3 self management – promoted through patient education and goal setting with clients, but impeded by limited focus on family and community-based activities due to understaffing; 4 decision support – facilitated by distribution of clinical guidelines and their integration with daily care, but limited by inadequate access to and support from specialists; 5 delivery system

  4. Study of dynamical properties in a bi-dimensional model describing the prey–predator dynamics with strong Allee effect in prey.

    Directory of Open Access Journals (Sweden)

    Partha Mandal

    2017-12-01

    Full Text Available In this work, we analyze a bi-dimensional differential equation system obtained by considering Holling type II functional response in prey–predator model with strong Allee effect in prey. One of the important consequence of this modification is the existence of separatrix curve which divides the behaviour of the trajectories in the phase plane. The results show that the origin is an attractor for any set of parameter values. Axial equilibrium points are stable or unstable according to the different parametric restrictions. The unique positive equilibrium point, if it exists, can be either an attractor or a repeller surrounded by a limit cycle, whose stability and uniqueness are also established. Therefore long-term coexistence of both populations is possible or they can go to extinction. Conditions on the parameter values are derived to show that the positive equilibrium point can be emerged or annihilated through transcritical bifurcation at axial equilibrium points. The existence of two heteroclinic curves is also established. It is also demonstrated that the origin is a global attractor in the phase plane for some parameter values, which implies that there are satisfying conditions where both populations can go to extinction. Ecological interpretations of all analytical results are provided thoroughly.

  5. Selection mechanisms underlying high impact biomedical research--a qualitative analysis and causal model.

    Directory of Open Access Journals (Sweden)

    Hilary Zelko

    Full Text Available BACKGROUND: Although scientific innovation has been a long-standing topic of interest for historians, philosophers and cognitive scientists, few studies in biomedical research have examined from researchers' perspectives how high impact publications are developed and why they are consistently produced by a small group of researchers. Our objective was therefore to interview a group of researchers with a track record of high impact publications to explore what mechanism they believe contribute to the generation of high impact publications. METHODOLOGY/PRINCIPAL FINDINGS: Researchers were located in universities all over the globe and interviews were conducted by phone. All interviews were transcribed using standard qualitative methods. A Grounded Theory approach was used to code each transcript, later aggregating concept and categories into overarching explanation model. The model was then translated into a System Dynamics mathematical model to represent its structure and behavior. Five emerging themes were found in our study. First, researchers used heuristics or rules of thumb that came naturally to them. Second, these heuristics were reinforced by positive feedback from their peers and mentors. Third, good communication skills allowed researchers to provide feedback to their peers, thus closing a positive feedback loop. Fourth, researchers exhibited a number of psychological attributes such as curiosity or open-mindedness that constantly motivated them, even when faced with discouraging situations. Fifth, the system is dominated by randomness and serendipity and is far from a linear and predictable environment. Some researchers, however, took advantage of this randomness by incorporating mechanisms that would allow them to benefit from random findings. The aggregation of these themes into a policy model represented the overall expected behavior of publications and their impact achieved by high impact researchers. CONCLUSIONS: The proposed

  6. A Reduced Duty Hours Model for Senior Internal Medicine Residents: A Qualitative Analysis of Residents' Experiences and Perceptions.

    Science.gov (United States)

    Mathew, Rebecca; Gundy, Serena; Ulic, Diana; Haider, Shariq; Wasi, Parveen

    2016-09-01

    To assess senior internal medicine residents' experience of the implementation of a reduced duty hours model with night float, the transition from the prior 26-hour call system, and the new model's effects on resident quality of life and perceived patient safety in the emergency department and clinical teaching unit at McMaster University. Qualitative data were collected during May 2013-July 2014, through resident focus groups held prior to implementation of a reduced duty hours model and 10 to 12 months postimplementation. Data analysis was guided by a constructivist grounded theory based in a relativist paradigm. Transcripts were coded; codes were collapsed into themes. Thematic analysis revealed five themes. Residents described reduced fatigue in the early morning, counterbalanced with worsened long-term fatigue on night float blocks; anticipation of negative impacts of the loss of distributed on-call experience and on-call shift volume; an urgency to sleep postcall in anticipation of consecutive night float shifts accompanied by conflicting role demands to stay postcall for care continuity; increased handover frequency accompanied by inaccurate/incomplete communication of patients' issues; and improvement in the senior resident experience on the clinical teaching unit, with increased ownership over patient care and improved relationships with junior housestaff. A reduced duty hours model with night float has potential to improve residents' perceived fatigue on call and care continuity on the clinical teaching unit. This must be weighed against increased handover frequency and loss of the postcall day, which may negatively affect patient care and resident quality of life.

  7. Chaotic-dynamical conceptual model to describe fluid flow and contaminant transport in a fractured vadose zone. 1998 annual progress report

    International Nuclear Information System (INIS)

    Doughty, C.; Dragila, M.I.; Faybishenko, B.; Podgorney, R.K.; Stoops, T.M.; Wheatcraft, S.W.; Wood, T.R.

    1998-01-01

    'DOE faces the remediation of numerous contaminated sites, such as those at Hanford, INEEL, LLNL, and LBNL, where organic and/or radioactive wastes were intentionally or accidentally released to the vadose zone from surface spills, underground tanks, cribs, shallow ponds, and deep wells. Migration of these contaminants through the vadose zone has lead to the contamination of or threatens to contaminate underlying groundwater. A key issue in choosing a corrective action plan to clean up contaminated sites is to determine the location, total mass, mobility and travel time to receptors for contaminants moving in the vadose zone. These problems are difficult to solve in a technically defensible and accurate manner because contaminants travel downward intermittently through narrow pathways driven by variations in environmental conditions. These preferential pathways can be difficult to find and predict. The primary objective of this project is to determine if and when dynamical chaos theory can be used to investigate infiltration of fluid and contaminant transport in heterogeneous soils and fractured rocks. The objective of this project is being achieved through the following Activities (1) Evaluation of chaotic behavior of flow in laboratory and field experiments using methods from non-linear dynamics; (2) Evaluation of the impact these dynamics may have on contaminant transport through heterogeneous fractured rocks and soils, and how it can be used to guide remediation efforts; (3) Development of a conceptual model and mathematical and numerical algorithms for flow and transport, which incorporate both: (a) the spatial variability of heterogeneous porous and fractured media, and (b) the description of the temporal dynamics of flow and transport, which may be chaotic; and (4) Development of appropriate experimental field and laboratory techniques needed to detect diagnostic parameters for chaotic behavior of flow. This approach is based on the assumption that spatial

  8. Preliminary clinical nursing leadership competency model: a qualitative study from Thailand.

    Science.gov (United States)

    Supamanee, Treeyaphan; Krairiksh, Marisa; Singhakhumfu, Laddawan; Turale, Sue

    2011-12-01

    This qualitative study explored the clinical nursing leadership competency perspectives of Thai nurses working in a university hospital. To collect data, in-depth interviews were undertaken with 23 nurse administrators, and focus groups were used with 31 registered nurses. Data were analyzed using content analysis, and theory development was guided by the Iceberg model. Nurses' clinical leadership competencies emerged, comprising hidden characteristics and surface characteristics. The hidden characteristics composed three elements: motive (respect from the nursing and healthcare team and being secure in life), self-concept (representing positive attitudes and values), and traits (personal qualities necessary for leadership). The surface characteristics comprised specific knowledge of nurse leaders about clinical leadership, management and nursing informatics, and clinical skills, such as coordination, effective communication, problem solving, and clinical decision-making. The study findings help nursing to gain greater knowledge of the essence of clinical nursing leadership competencies, a matter critical for theory development in leadership. This study's results later led to the instigation of a training program for registered nurse leaders at the study site, and the formation of a preliminary clinical nursing leadership competency model. © 2011 Blackwell Publishing Asia Pty Ltd.

  9. Phoenix – A model-based Human Reliability Analysis methodology: Qualitative Analysis Procedure

    International Nuclear Information System (INIS)

    Ekanem, Nsimah J.; Mosleh, Ali; Shen, Song-Hua

    2016-01-01

    Phoenix method is an attempt to address various issues in the field of Human Reliability Analysis (HRA). Built on a cognitive human response model, Phoenix incorporates strong elements of current HRA good practices, leverages lessons learned from empirical studies, and takes advantage of the best features of existing and emerging HRA methods. Its original framework was introduced in previous publications. This paper reports on the completed methodology, summarizing the steps and techniques of its qualitative analysis phase. The methodology introduces the “Crew Response Tree” which provides a structure for capturing the context associated with Human Failure Events (HFEs), including errors of omission and commission. It also uses a team-centered version of the Information, Decision and Action cognitive model and “macro-cognitive” abstractions of crew behavior, as well as relevant findings from cognitive psychology literature and operating experience, to identify potential causes of failures and influencing factors during procedure-driven and knowledge-supported crew-plant interactions. The result is the set of identified HFEs and likely scenarios leading to each. The methodology itself is generic in the sense that it is compatible with various quantification methods, and can be adapted for use across different environments including nuclear, oil and gas, aerospace, aviation, and healthcare. - Highlights: • Produces a detailed, consistent, traceable, reproducible and properly documented HRA. • Uses “Crew Response Tree” to capture context associated with Human Failure Events. • Models dependencies between Human Failure Events and influencing factors. • Provides a human performance model for relating context to performance. • Provides a framework for relating Crew Failure Modes to its influencing factors.

  10. Getting added value from using qualitative research with randomized controlled trials: a qualitative interview study

    Science.gov (United States)

    2014-01-01

    Background Qualitative research is undertaken with randomized controlled trials of health interventions. Our aim was to explore the perceptions of researchers with experience of this endeavour to understand the added value of qualitative research to the trial in practice. Methods A telephone semi-structured interview study with 18 researchers with experience of undertaking the trial and/or the qualitative research. Results Interviewees described the added value of qualitative research for the trial, explaining how it solved problems at the pretrial stage, explained findings, and helped to increase the utility of the evidence generated by the trial. From the interviews, we identified three models of relationship of the qualitative research to the trial. In ‘the peripheral’ model, the trial was an opportunity to undertake qualitative research, with no intention that it would add value to the trial. In ‘the add-on’ model, the qualitative researcher understood the potential value of the qualitative research but it was viewed as a separate and complementary endeavour by the trial lead investigator and wider team. Interviewees described how this could limit the value of the qualitative research to the trial. Finally ‘the integral’ model played out in two ways. In ‘integral-in-theory’ studies, the lead investigator viewed the qualitative research as essential to the trial. However, in practice the qualitative research was under-resourced relative to the trial, potentially limiting its ability to add value to the trial. In ‘integral-in-practice’ studies, interviewees described how the qualitative research was planned from the beginning of the study, senior qualitative expertise was on the team from beginning to end, and staff and time were dedicated to the qualitative research. In these studies interviewees described the qualitative research adding value to the trial although this value was not necessarily visible beyond the original research team due

  11. Getting added value from using qualitative research with randomized controlled trials: a qualitative interview study.

    Science.gov (United States)

    O'Cathain, Alicia; Goode, Jackie; Drabble, Sarah J; Thomas, Kate J; Rudolph, Anne; Hewison, Jenny

    2014-06-09

    Qualitative research is undertaken with randomized controlled trials of health interventions. Our aim was to explore the perceptions of researchers with experience of this endeavour to understand the added value of qualitative research to the trial in practice. A telephone semi-structured interview study with 18 researchers with experience of undertaking the trial and/or the qualitative research. Interviewees described the added value of qualitative research for the trial, explaining how it solved problems at the pretrial stage, explained findings, and helped to increase the utility of the evidence generated by the trial. From the interviews, we identified three models of relationship of the qualitative research to the trial. In 'the peripheral' model, the trial was an opportunity to undertake qualitative research, with no intention that it would add value to the trial. In 'the add-on' model, the qualitative researcher understood the potential value of the qualitative research but it was viewed as a separate and complementary endeavour by the trial lead investigator and wider team. Interviewees described how this could limit the value of the qualitative research to the trial. Finally 'the integral' model played out in two ways. In 'integral-in-theory' studies, the lead investigator viewed the qualitative research as essential to the trial. However, in practice the qualitative research was under-resourced relative to the trial, potentially limiting its ability to add value to the trial. In 'integral-in-practice' studies, interviewees described how the qualitative research was planned from the beginning of the study, senior qualitative expertise was on the team from beginning to end, and staff and time were dedicated to the qualitative research. In these studies interviewees described the qualitative research adding value to the trial although this value was not necessarily visible beyond the original research team due to the challenges of publishing this research

  12. Motives and preferences of general practitioners for new collaboration models with medical specialists: a qualitative study

    Directory of Open Access Journals (Sweden)

    Klazinga Niek S

    2007-01-01

    Full Text Available Abstract Background Collaboration between general practitioners (GPs and specialists has been the focus of many collaborative care projects during the past decade. Unfortunately, quite a number of these projects failed. This raises the question of what motivates GPs to initiate and continue participating with medical specialists in new collaborative care models. The following two questions are addressed in this study: What motivates GPs to initiate and sustain new models for collaborating with medical specialists? What kind of new collaboration models do GPs suggest? Methods A qualitative study design was used. Starting in 2003 and finishing in 2005, we conducted semi-structured interviews with a purposive sample of 21 Dutch GPs. The sampling criteria were age, gender, type of practice, and practice site. The interviews were recorded, fully transcribed, and analysed by two researchers working independently. The resulting motivational factors and preferences were grouped into categories. Results 'Developing personal relationships' and 'gaining mutual respect' appeared to dominate when the motivational factors were considered. Besides developing personal relationships with specialists, the GPs were also interested in familiarizing specialists with the competencies attached to the profession of family medicine. Additionally, they were eager to increase their medical knowledge to the benefit of their patients. The GPs stated a variety of preferences with respect to the design of new models of collaboration. Conclusion Developing personal relationships with specialists appeared to be one of the dominant motives for increased collaboration. Once the relationships have been formed, an informal network with occasional professional contact seemed sufficient. Although GPs are interested in increasing their knowledge, once they have reached a certain level of expertise, they shift their focus to another specialty. The preferences for new collaboration

  13. Qualitative properties and hopf bifurcation in haematopoietic disease model with chemotherapy

    Directory of Open Access Journals (Sweden)

    Yafia R.

    2014-01-01

    Full Text Available In this paper, we consider a model describing the dynamics of Hematopoietic Stem Cells (HSC disease with chemotherapy. The model is given by a system of three ordinary differential equations with discrete delay. Its dynamics are studied in term of local stability of the possible steady states for the case without drug intervention term. We prove the existence of periodic oscillations for each case when the delay passes trough a critical values. In the end, we illustrate our results by some numerical simulations.

  14. Blackboard architecture and qualitative model in a computer aided assistant designed to define computers for HEP computing

    International Nuclear Information System (INIS)

    Nodarse, F.F.; Ivanov, V.G.

    1991-01-01

    Using BLACKBOARD architecture and qualitative model, an expert systm was developed to assist the use in defining the computers method for High Energy Physics computing. The COMEX system requires an IBM AT personal computer or compatible with than 640 Kb RAM and hard disk. 5 refs.; 9 figs

  15. Oxygen distribution in tumors: A qualitative analysis and modeling study providing a novel Monte Carlo approach

    International Nuclear Information System (INIS)

    Lagerlöf, Jakob H.; Kindblom, Jon; Bernhardt, Peter

    2014-01-01

    end, due to anoxia, but smaller tumors showed undisturbed oxygen distributions. The six different models with correlated parameters generated three classes of oxygen distributions. The first was a hypothetical, negative covariance between vessel proximity and pO 2 (VPO-C scenario); the second was a hypothetical positive covariance between vessel proximity and pO 2 (VPO+C scenario); and the third was the hypothesis of no correlation between vessel proximity and pO 2 (UP scenario). The VPO-C scenario produced a distinctly different oxygen distribution than the two other scenarios. The shape of the VPO-C scenario was similar to that of the nonvariable DOC model, and the larger the tumor, the greater the similarity between the two models. For all simulations, the mean oxygen tension decreased and the hypoxic fraction increased with tumor size. The absorbed dose required for definitive tumor control was highest for the VPO+C scenario, followed by the UP and VPO-C scenarios. Conclusions: A novel MC algorithm was presented which simulated oxygen distributions and radiation response for various biological parameter values. The analysis showed that the VPO-C scenario generated a clearly different oxygen distribution from the VPO+C scenario; the former exhibited a lower hypoxic fraction and higher radiosensitivity. In future studies, this modeling approach might be valuable for qualitative analyses of factors that affect oxygen distribution as well as analyses of specific experimental and clinical situations

  16. Performance of density functional theory methods to describe ...

    Indian Academy of Sciences (India)

    Unknown

    Chemical compounds present different types of isomer- ism. When two isomers differ by ... of DFT methods to describe intramolecular hydrogen shifts. Three small ..... qualitative descriptions of intramolecular hydrogen shifts when large basis ...

  17. Experienced Practitioners’ Beliefs Utilized to Create a Successful Massage Therapist Conceptual Model: a Qualitative Investigation

    Science.gov (United States)

    Kennedy, Anne B.; Munk, Niki

    2017-01-01

    Background The massage therapy profession in the United States has grown exponentially, with 35% of the profession’s practitioners in practice for three years or less. Investigating personal and social factors with regard to the massage therapy profession could help to identify constructs needed to be successful in the field. Purpose This data-gathering exercise explores massage therapists’ perceptions on what makes a successful massage therapist that will provide guidance for future research. Success is defined as supporting oneself and practice solely through massage therapy and related, revenue-generating field activity. Participants and Setting Ten successful massage therapy practitioners from around the United States who have a minimum of five years of experience. Research Design Semistructured qualitative interviews were used in an analytic induction framework; index cards with preidentified concepts printed on them were utilized to enhance conversation. An iterative process of interview coding and analysis was used to determine themes and subthemes. Results Based on the participants input, the categories in which therapists needed to be successful were organized into four main themes: effectively establish therapeutic relationships, develop massage therapy business acumen, seek valuable learning environments and opportunities, and cultivate strong social ties and networks. The four themes operate within specific contexts (e.g., regulation and licensing requirements in the therapists’ state), which may also influence the success of the massage therapist. Conclusions The model needs to be tested to explore which constructs explain variability in success and attrition rate. Limitations and future research implications are discussed. PMID:28690704

  18. Designing a Qualitative Model of Doping Phenomenon Effect on Sport Marketing in Iran

    Directory of Open Access Journals (Sweden)

    Jasem Manouchehri

    2016-10-01

    Full Text Available There a number of factors effecting consumers' purchase behavior. It is believed that celebrities can effect selling positively by transferring their popular image to the endorsed product. But, it is heard lots about excommunicate behaviors in the sport world today. Disclosure of the recent doping affairs relating to Lance Armstrong's seven wins in Tour De France is just one among many spectacular and also negative cases. The main aim of the present paper was to explore the effect of doping phenomenon on sport marketing. Depth interviews data were analyzed in three phases: open coding, axial coding, and selective coding. 297 open codes were achieved by 18 interviews. Grouping axial codes in each case and comparing, all gained codes can be divided in five groups: brand image (athlete and endorsed product brands images, moral reasoning (moral coupling, moral decoupling, and moral rationalization, consumer behavioral consequences (word of mouth, purchasing intention, and brand loyalty, attitude change (attitudes change toward athlete and brand, and moral emotions (moral evaluation, contempt, anger, disgust, and sympathy. The proposed qualitative model for the effect of doping phenomenon on sport marketing in Iran illustrated that moral emotions and product brand image affected by the doped athlete brand image and it resulted in attitudes change toward endorser athlete and endorsed brand and negative consumer behavioral consequences, however, moral reasoning strategies emerged by cognitive dissonance might protect consumers behavior from negative effects.

  19. Business Models, Vaccination Services, and Public Health Relationships of Retail Clinics: A Qualitative Study.

    Science.gov (United States)

    Arthur, Bayo C; Fisher, Allison Kennedy; Shoemaker, Sarah J; Pozniak, Alyssa; Stokley, Shannon

    2015-01-01

    Despite the rapid growth of retail clinics (RCs), literature is limited in terms of how these facilities offer preventive services, particularly vaccination services. The purpose of this study was to obtain an in-depth understanding of the RC business model pertaining to vaccine offerings, profitability, and decision making. From March to June 2009, we conducted 15 interviews with key individuals from three types of organizations: 12 representatives of RC corporations, 2 representatives of retail hosts (i.e., stores in which the RCs are located), and 1 representative of an industry association. We analyzed interview transcripts qualitatively. Our results indicate that consumer demand and profitability were the main drivers in offering vaccinations. RCs in this sample primarily offered vaccinations to adults and adolescents, and they were not well integrated with local public health and immunization registries. Our findings demonstrate the potential for stronger linkages with public health in these settings. The findings also may help inform future research to increase patient access to vaccination services at RCs.

  20. Experienced Practitioners' Beliefs Utilized to Create a Successful Massage Therapist Conceptual Model: a Qualitative Investigation.

    Science.gov (United States)

    Kennedy, Anne B; Munk, Niki

    2017-06-01

    The massage therapy profession in the United States has grown exponentially, with 35% of the profession's practitioners in practice for three years or less. Investigating personal and social factors with regard to the massage therapy profession could help to identify constructs needed to be successful in the field. This data-gathering exercise explores massage therapists' perceptions on what makes a successful massage therapist that will provide guidance for future research. Success is defined as supporting oneself and practice solely through massage therapy and related, revenue-generating field activity. Ten successful massage therapy practitioners from around the United States who have a minimum of five years of experience. Semistructured qualitative interviews were used in an analytic induction framework; index cards with preidentified concepts printed on them were utilized to enhance conversation. An iterative process of interview coding and analysis was used to determine themes and subthemes. Based on the participants input, the categories in which therapists needed to be successful were organized into four main themes: effectively establish therapeutic relationships, develop massage therapy business acumen, seek valuable learning environments and opportunities, and cultivate strong social ties and networks. The four themes operate within specific contexts (e.g., regulation and licensing requirements in the therapists' state), which may also influence the success of the massage therapist. The model needs to be tested to explore which constructs explain variability in success and attrition rate. Limitations and future research implications are discussed.

  1. Qualitative evaluation of adherence therapy in Parkinson’s disease: a multidirectional model

    Directory of Open Access Journals (Sweden)

    Daley DJ

    2015-07-01

    Full Text Available David James Daley,1,2 Katherine Helen O’Leary Deane,3 Richard John Gray,4 Rebekah Hill,3 Phyo Kyaw Myint5 1Norwich Medical School, Faculty of Medicine and Health Sciences, University of East Anglia, Norwich Research Park, 2Norfolk and Norwich University Hospital NHS Foundation Trust, 3School of Health Sciences, University of East Anglia, Norwich Research Park, Norwich, UK; 4Hamad Medical Corporation, Doha, Qatar; 5Epidemiology Group, School of Medicine and Dentistry, Institute of Applied Health Sciences, College of Life Sciences and Medicine, University of Aberdeen, Aberdeen, UK Background: Medication can control the symptoms of Parkinson’s disease (PD. Despite this, non-adherence with medication is prevalent in PD. Treatments for improving adherence with medication have been investigated in many chronic conditions, including PD. However, few researchers have evaluated their interventions qualitatively. We investigated the acceptability and potential mechanism of action of adherence therapy (AT in PD patients and their spouse/carers who received the intervention as part of a randomized controlled trial. Methods: Sixteen participants (ten patients and six spouses/carers who had recently completed the trial were purposely selected in order to cover a range of ages and disease severity. Semi-structured interviews were conducted in the participants’ homes. Data were transcribed and analyzed using a thematic approach. A second researcher, naïve to PD and AT, analyzed the data independently to limit bias. Results: The trial showed that AT significantly improved both medication adherence and quality of life in people with PD. Specifically, patients who received AT reported improvements in mobility, activities of daily living, emotional wellbeing, cognition, communication, and body discomfort. General beliefs about medication also significantly improved in those who received AT compared with controls. In the current qualitative evaluation, a

  2. Qualitatively Modeling solute fate and transport across scales in an agricultural catchment with diverse lithology

    Science.gov (United States)

    Wayman, C. R.; Russo, T. A.; Li, L.; Forsythe, B.; Hoagland, B.

    2017-12-01

    As part of the Susquehanna Shale Hills Critical Zone Observatory (SSHCZO) project, we have collected geochemical and hydrological data from several subcatchments and four monitoring sites on the main stem of Shaver's Creek, in Huntingon county, Pennsylvania. One subcatchment (0.43 km2) is under agricultural land use, and the monitoring locations on the larger Shaver's Creek (up to 163 km2) drain watersheds with 0 to 25% agricultural area. These two scales of investigation, coupled with advances made across the SSHCZO on multiple lithologies allow us to extrapolate from the subcatchment to the larger watershed. We use geochemical surface and groundwater data to estimate the solute and water transport regimes within the catchment, and to show how lithology and land use are major controls on ground and surface water quality. One area of investigation includes the transport of nutrients between interflow and regional groundwater, and how that connectivity may be reflected in local surface waters. Water and nutrient (Nitrogen) isotopes, will be used to better understand the relative contributions of local and regional groundwater and interflow fluxes into nearby streams. Following initial qualitative modeling, multiple hydrologic and nutrient transport models (e.g. SWAT and CYCLES/PIHM) will be evaluated from the subcatchment to large watershed scales. We will evaluate the ability to simulate the contributions of regional groundwater versus local groundwater, and also impacts of agricultural land management on surface water quality. Improving estimations of groundwater contributions to stream discharge will provide insight into how much agricultural development can impact stream quality and nutrient loading.

  3. Simplified Qualitative Discrete Numerical Model to Determine Cracking Pattern in Brittle Materials by Means of Finite Element Method

    OpenAIRE

    Ochoa-Avendaño, J.; Garzon-Alvarado, D. A.; Linero, Dorian L.; Cerrolaza, M.

    2017-01-01

    This paper presents the formulation, implementation, and validation of a simplified qualitative model to determine the crack path of solids considering static loads, infinitesimal strain, and plane stress condition. This model is based on finite element method with a special meshing technique, where nonlinear link elements are included between the faces of the linear triangular elements. The stiffness loss of some link elements represents the crack opening. Three experimental tests of bending...

  4. Five Describing Factors of Dyslexia

    Science.gov (United States)

    Tamboer, Peter; Vorst, Harrie C. M.; Oort, Frans J.

    2016-01-01

    Two subtypes of dyslexia (phonological, visual) have been under debate in various studies. However, the number of symptoms of dyslexia described in the literature exceeds the number of subtypes, and underlying relations remain unclear. We investigated underlying cognitive features of dyslexia with exploratory and confirmatory factor analyses. A…

  5. An integrated qualitative and quantitative modeling framework for computer‐assisted HAZOP studies

    DEFF Research Database (Denmark)

    Wu, Jing; Zhang, Laibin; Hu, Jinqiu

    2014-01-01

    safety critical operations, its causes and consequences. The outcome is a qualitative hazard analysis of selected process deviations from normal operations and their consequences as input to a traditional HAZOP table. The list of unacceptable high risk deviations identified by the qualitative HAZOP......‐assisted HAZOP studies introduced in this article allows the HAZOP team to devote more attention to high consequence hazards. © 2014 American Institute of Chemical Engineers AIChE J 60: 4150–4173, 2014...

  6. Disease management projects and the Chronic Care Model in action: baseline qualitative research

    Science.gov (United States)

    2012-01-01

    Background Disease management programs, especially those based on the Chronic Care Model (CCM), are increasingly common in the Netherlands. While disease management programs have been well-researched quantitatively and economically, less qualitative research has been done. The overall aim of the study is to explore how disease management programs are implemented within primary care settings in the Netherlands; this paper focuses on the early development and implementation stages of five disease management programs in the primary care setting, based on interviews with project leadership teams. Methods Eleven semi-structured interviews were conducted at the five selected sites with sixteen professionals interviewed; all project directors and managers were interviewed. The interviews focused on each project’s chosen chronic illness (diabetes, eating disorders, COPD, multi-morbidity, CVRM) and project plan, barriers to development and implementation, the project leaders’ action and reactions, as well as their roles and responsibilities, and disease management strategies. Analysis was inductive and interpretive, based on the content of the interviews. After analysis, the results of this research on disease management programs and the Chronic Care Model are viewed from a traveling technology framework. Results This analysis uncovered four themes that can be mapped to disease management and the Chronic Care Model: (1) changing the health care system, (2) patient-centered care, (3) technological systems and barriers, and (4) integrating projects into the larger system. Project leaders discussed the paths, both direct and indirect, for transforming the health care system to one that addresses chronic illness. Patient-centered care was highlighted as needed and a paradigm shift for many. Challenges with technological systems were pervasive. Project leaders managed the expenses of a traveling technology, including the social, financial, and administration involved

  7. Disease management projects and the Chronic Care Model in action: baseline qualitative research.

    Science.gov (United States)

    Walters, Bethany Hipple; Adams, Samantha A; Nieboer, Anna P; Bal, Roland

    2012-05-11

    Disease management programs, especially those based on the Chronic Care Model (CCM), are increasingly common in The Netherlands. While disease management programs have been well-researched quantitatively and economically, less qualitative research has been done. The overall aim of the study is to explore how disease management programs are implemented within primary care settings in The Netherlands; this paper focuses on the early development and implementation stages of five disease management programs in the primary care setting, based on interviews with project leadership teams. Eleven semi-structured interviews were conducted at the five selected sites with sixteen professionals interviewed; all project directors and managers were interviewed. The interviews focused on each project's chosen chronic illness (diabetes, eating disorders, COPD, multi-morbidity, CVRM) and project plan, barriers to development and implementation, the project leaders' action and reactions, as well as their roles and responsibilities, and disease management strategies. Analysis was inductive and interpretive, based on the content of the interviews. After analysis, the results of this research on disease management programs and the Chronic Care Model are viewed from a traveling technology framework. This analysis uncovered four themes that can be mapped to disease management and the Chronic Care Model: (1) changing the health care system, (2) patient-centered care, (3) technological systems and barriers, and (4) integrating projects into the larger system. Project leaders discussed the paths, both direct and indirect, for transforming the health care system to one that addresses chronic illness. Patient-centered care was highlighted as needed and a paradigm shift for many. Challenges with technological systems were pervasive. Project leaders managed the expenses of a traveling technology, including the social, financial, and administration involved. At the sites, project leaders served

  8. Navigating the complexities of qualitative comparative analysis: case numbers, necessity relations, and model ambiguities.

    Science.gov (United States)

    Thiem, Alrik

    2014-12-01

    In recent years, the method of Qualitative Comparative Analysis (QCA) has been enjoying increasing levels of popularity in evaluation and directly neighboring fields. Its holistic approach to causal data analysis resonates with researchers whose theories posit complex conjunctions of conditions and events. However, due to QCA's relative immaturity, some of its technicalities and objectives have not yet been well understood. In this article, I seek to raise awareness of six pitfalls of employing QCA with regard to the following three central aspects: case numbers, necessity relations, and model ambiguities. Most importantly, I argue that case numbers are irrelevant to the methodological choice of QCA or any of its variants, that necessity is not as simple a concept as it has been suggested by many methodologists, and that doubt must be cast on the determinacy of virtually all results presented in past QCA research. By means of empirical examples from published articles, I explain the background of these pitfalls and introduce appropriate procedures, partly with reference to current software, that help avoid them. QCA carries great potential for scholars in evaluation and directly neighboring areas interested in the analysis of complex dependencies in configurational data. If users beware of the pitfalls introduced in this article, and if they avoid mechanistic adherence to doubtful "standards of good practice" at this stage of development, then research with QCA will gain in quality, as a result of which a more solid foundation for cumulative knowledge generation and well-informed policy decisions will also be created. © The Author(s) 2014.

  9. Overview of qualitative research.

    Science.gov (United States)

    Grossoehme, Daniel H

    2014-01-01

    Qualitative research methods are a robust tool for chaplaincy research questions. Similar to much of chaplaincy clinical care, qualitative research generally works with written texts, often transcriptions of individual interviews or focus group conversations and seeks to understand the meaning of experience in a study sample. This article describes three common methodologies: ethnography, grounded theory, and phenomenology. Issues to consider relating to the study sample, design, and analysis are discussed. Enhancing the validity of the data, as well reliability and ethical issues in qualitative research are described. Qualitative research is an accessible way for chaplains to contribute new knowledge about the sacred dimension of people's lived experience.

  10. Prediction of qualitative parameters of slab steel ingot using numerical modelling

    Directory of Open Access Journals (Sweden)

    M. Tkadlečková

    2016-07-01

    Full Text Available The paper describes the verification of casting and solidification of heavy slab ingot weighing 40 t from tool steel by means of numerical modelling with use of a finite element method. The pre-processing, processing and post-processing phases of numerical modelling are outlined. Also, the problems with determination of the thermodynamic properties of materials and with determination of the heat transfer between the individual parts of the casting system are discussed. The final porosity, macrosegregation and the risk of cracks were predicted. The results allowed us to use the slab ingot instead of the conventional heavy steel ingot and to improve the ratio, the chamfer and the external shape of the wall of the new design of the slab ingot.

  11. GMM - a general microstructural model for qualitative and quantitative studies of smectite clays

    International Nuclear Information System (INIS)

    Pusch, R.; Karnland, O.; Hoekmark, H.

    1990-12-01

    A few years ago an attempt was made to accommodate a number of basic ideas on the fabric and interparticle forces that are assumed to be valid in montmorillonite clay in an integrated microstructural model and this resulted in an SKB report on 'Outlines of models of water and gas flow through smectite clay buffers'. This model gave reasonable agreement between predicted hydraulic conductivity values and actually recorded ones for room temperature and porewater that is poor in electrolytes. The present report describes an improved model that also accounts for effects generated by salt porewater and heating, and that provides a basis for both quantitative determination of transport capacities in a more general way, and also for analysis and prediction of rheological behaviour in bulk. It has been understood very early by investigators in this scientific field that full understanding of the physical state of porewater is asked for in order to make it possible to develop models for clay particle interaction. In particular, a deep insight in the nature of the interlamellar water and of the hydration mechanisms leading to an equilibrium state between the two types of water, and of forcefields in matured smectite clay, requires very qualified multi-discipline research and attempts have been made by the senior author to initiate and coordinate such work in the last 30 years. Despite this effort it has not been possible to get an unanimous understanding of these things but a number of major features have become more clear through the work that we have been able to carry out in the current SKB research work. Thus, NMR studies and precision measurements of the density of porewater as well as comprehensive electron microscopy and rheological testing in combination with application of stochastical mechanics, have led to the hypothetical microstructural model - the GMM - presented in this report. (au)

  12. Describing treatment effects to patients.

    Science.gov (United States)

    Moxey, Annette; O'Connell, Dianne; McGettigan, Patricia; Henry, David

    2003-11-01

    To examine the impact of different presentations of equivalent information (framing) on treatment decisions faced by patients. A systematic review of the published literature was conducted. English language publications allocating participants to different frames were retrieved using electronic and bibliographic searches. Two reviewers examined each article for inclusion, and assessed methodological quality. Study characteristics were tabulated and where possible, relative risks (RR; 95% confidence intervals) were calculated to estimate intervention effects. Thirty-seven articles, yielding 40 experimental studies, were included. Studies examined treatment (N = 24), immunization (N = 5), or health behavior scenarios (N = 11). Overall, active treatments were preferred when outcomes were described in terms of relative rather than absolute risk reductions or number needed to treat. Surgery was preferred to other treatments when treatment efficacy was presented in a positive frame (survival) rather than a negative frame (mortality) (relative risk [RR] = 1.51, 95% confidence interval [CI], 1.39 to 1.64). Framing effects were less obvious for immunization and health behavior scenarios. Those with little interest in the behavior at baseline were influenced by framing, particularly when information was presented as gains. In studies judged to be of good methodological quality and/or examining actual decisions, the framing effect, although still evident, was less convincing compared to the results of all included studies. Framing effects varied with the type of scenario, responder characteristics, scenario manipulations, and study quality. When describing treatment effects to patients, expressing the information in more than one way may present a balanced view to patients and enable them to make informed decisions.

  13. Qualitative analysis of cosmological models in Brans-Dicke theory, solutions from non-minimal coupling and viscous universe

    International Nuclear Information System (INIS)

    Romero Filho, C.A.

    1988-01-01

    Using dynamical system theory we investigate homogeneous and isotropic models in Brans-Dicke theory for perfect fluids with general equation of state and arbitrary ω. Phase diagrams are drawn on the Poincare sphere which permits a qualitative analysis of the models. Based on this analysis we construct a method for generating classes of solutions in Brans-Dicke theory. The same technique is used for studying models arising from non-minimal coupling of electromagnetism with gravity. In addition, viscous fluids are considered and non-singular solutions with bulk viscosity are found. (author)

  14. Stochastic GARCH dynamics describing correlations between stocks

    Science.gov (United States)

    Prat-Ortega, G.; Savel'ev, S. E.

    2014-09-01

    The ARCH and GARCH processes have been successfully used for modelling price dynamics such as stock returns or foreign exchange rates. Analysing the long range correlations between stocks, we propose a model, based on the GARCH process, which is able to describe the main characteristics of the stock price correlations, including the mean, variance, probability density distribution and the noise spectrum.

  15. Qualitative Analysis of a Diffusive Ratio-Dependent Holling-Tanner Predator-Prey Model with Smith Growth

    Directory of Open Access Journals (Sweden)

    Zongmin Yue

    2013-01-01

    Full Text Available We investigated the dynamics of a diffusive ratio-dependent Holling-Tanner predator-prey model with Smith growth subject to zero-flux boundary condition. Some qualitative properties, including the dissipation, persistence, and local and global stability of positive constant solution, are discussed. Moreover, we give the refined a priori estimates of positive solutions and derive some results for the existence and nonexistence of nonconstant positive steady state.

  16. Models for integrating medical acupuncture into practice: an exploratory qualitative study of physicians' experiences.

    Science.gov (United States)

    Crumley, Ellen T

    2016-08-01

    Internationally, physicians are integrating medical acupuncture into their practice. Although there are some informative surveys and reviews, there are few international, exploratory studies detailing how physicians have accommodated medical acupuncture (eg, by modifying schedules, space and processes). To examine how physicians integrate medical acupuncture into their practice. Semi-structured interviews and participant observations of physicians practising medical acupuncture were conducted using convenience and snowball sampling. Data were analysed in NVivo and themes were developed. Despite variation, three principal models were developed to summarise the different ways that physicians integrated medical acupuncture into their practice, using the core concept of 'helping'. Quotes were used to illustrate each model and its corresponding themes. There were 25 participants from 11 countries: 21 agreed to be interviewed and four engaged in participant observations. Seventy-two per cent were general practitioners. The three models were: (1) appointments (44%); (2) clinics (44%); and (3) full-time practice (24%). Some physicians held both appointments and regular clinics (models 1 and 2). Most full-time physicians initially tried appointments and/or clinics. Some physicians charged to offset administration costs or compensate for their time. Despite variation within each category, the three models encapsulated how physicians described their integration of medical acupuncture. Physicians varied in how often they administered medical acupuncture and the amount of time they spent with patients. Although 24% of physicians surveyed administered medical acupuncture full-time, most practised it part-time. Each individual physician incorporated medical acupuncture in the way that worked best for their practice. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  17. Qualitative versus quantitative methods in psychiatric research.

    Science.gov (United States)

    Razafsha, Mahdi; Behforuzi, Hura; Azari, Hassan; Zhang, Zhiqun; Wang, Kevin K; Kobeissy, Firas H; Gold, Mark S

    2012-01-01

    Qualitative studies are gaining their credibility after a period of being misinterpreted as "not being quantitative." Qualitative method is a broad umbrella term for research methodologies that describe and explain individuals' experiences, behaviors, interactions, and social contexts. In-depth interview, focus groups, and participant observation are among the qualitative methods of inquiry commonly used in psychiatry. Researchers measure the frequency of occurring events using quantitative methods; however, qualitative methods provide a broader understanding and a more thorough reasoning behind the event. Hence, it is considered to be of special importance in psychiatry. Besides hypothesis generation in earlier phases of the research, qualitative methods can be employed in questionnaire design, diagnostic criteria establishment, feasibility studies, as well as studies of attitude and beliefs. Animal models are another area that qualitative methods can be employed, especially when naturalistic observation of animal behavior is important. However, since qualitative results can be researcher's own view, they need to be statistically confirmed, quantitative methods. The tendency to combine both qualitative and quantitative methods as complementary methods has emerged over recent years. By applying both methods of research, scientists can take advantage of interpretative characteristics of qualitative methods as well as experimental dimensions of quantitative methods.

  18. A mathematical model for describing the retinal nerve fiber bundle trajectories in the human eye : Average course, variability, and influence of refraction, optic disc size and optic disc position

    NARCIS (Netherlands)

    Jansonius, Nomdo M.; Schiefer, Julia; Nevalainen, Jukka; Paetzold, Jens; Schiefer, Ulrich

    2012-01-01

    Previously we developed a mathematical model for describing the retinal nerve fiber bundle trajectories in the superior-temporal and inferior-temporal regions of the human retina, based on traced trajectories extracted from fundus photographs. Aims of the current study were to (i) validate the

  19. Fundamental Moral Attitudes to Animals and Their Role in Judgment: An Empirical Model to Describe Fundamental Moral Attitudes to Animals and Their Role in Judgment on the Culling of Healthy Animals During an Animal Disease Epidemic

    NARCIS (Netherlands)

    Cohen, N.E.; Brom, F.W.A.; Stassen, E.N.

    2009-01-01

    In this paper, we present and defend the theoretical framework of an empirical model to describe people’s fundamental moral attitudes (FMAs) to animals, the stratification of FMAs in society and the role of FMAs in judgment on the culling of healthy animals in an animal disease epidemic. We used

  20. Probability of identification (POI): a statistical model for the validation of qualitative botanical identification methods

    Science.gov (United States)

    A qualitative botanical identification method (BIM) is an analytical procedure which returns a binary result (1 = Identified, 0 = Not Identified). A BIM may be used by a buyer, manufacturer, or regulator to determine whether a botanical material being tested is the same as the target (desired) mate...

  1. Qualitative and quantitative combined nonlinear dynamics model and its application in analysis of price, supply–demand ratio and selling rate

    International Nuclear Information System (INIS)

    Zhu, Dingju

    2016-01-01

    The qualitative and quantitative combined nonlinear dynamics model proposed in this paper fill the gap in nonlinear dynamics model in terms of qualitative and quantitative combined methods, allowing the qualitative model and quantitative model to perfectly combine and overcome their weaknesses by learning from each other. These two types of models use their strengths to make up for the other’s deficiencies. The qualitative and quantitative combined models can surmount the weakness that the qualitative model cannot be applied and verified in a quantitative manner, and the high costs and long time of multiple construction as well as verification of the quantitative model. The combined model is more practical and efficient, which is of great significance for nonlinear dynamics. The qualitative and quantitative combined modeling and model analytical method raised in this paper is not only applied to nonlinear dynamics, but can be adopted and drawn on in the modeling and model analysis of other fields. Additionally, the analytical method of qualitative and quantitative combined nonlinear dynamics model proposed in this paper can satisfactorily resolve the problems with the price system’s existing nonlinear dynamics model analytical method. The three-dimensional dynamics model of price, supply–demand ratio and selling rate established in this paper make estimates about the best commodity prices using the model results, thereby providing a theoretical basis for the government’s macro-control of price. Meanwhile, this model also offer theoretical guidance to how to enhance people’s purchasing power and consumption levels through price regulation and hence to improve people’s living standards.

  2. Role Models and Teachers: medical students perception of teaching-learning methods in clinical settings, a qualitative study from Sri Lanka.

    Science.gov (United States)

    Jayasuriya-Illesinghe, Vathsala; Nazeer, Ishra; Athauda, Lathika; Perera, Jennifer

    2016-02-09

    Medical education research in general, and those focusing on clinical settings in particular, have been a low priority in South Asia. This explorative study from 3 medical schools in Sri Lanka, a South Asian country, describes undergraduate medical students' experiences during their final year clinical training with the aim of understanding the teaching-learning experiences. Using qualitative methods we conducted an exploratory study. Twenty eight graduates from 3 medical schools participated in individual interviews. Interview recordings were transcribed verbatim and analyzed using qualitative content analysis method. Emergent themes reveled 2 types of teaching-learning experiences, role modeling, and purposive teaching. In role modelling, students were expected to observe teachers while they conduct their clinical work, however, this method failed to create positive learning experiences. The clinical teachers who predominantly used this method appeared to be 'figurative' role models and were not perceived as modelling professional behaviors. In contrast, purposeful teaching allowed dedicated time for teacher-student interactions and teachers who created these learning experiences were more likely to be seen as 'true' role models. Students' responses and reciprocations to these interactions were influenced by their perception of teachers' behaviors, attitudes, and the type of teaching-learning situations created for them. Making a distinction between role modeling and purposeful teaching is important for students in clinical training settings. Clinical teachers' awareness of their own manifest professional characterizes, attitudes, and behaviors, could help create better teaching-learning experiences. Moreover, broader systemic reforms are needed to address the prevailing culture of teaching by humiliation and subordination.

  3. A systematic review and qualitative analysis to inform the development of a new emergency department-based geriatric case management model.

    Science.gov (United States)

    Sinha, Samir K; Bessman, Edward S; Flomenbaum, Neal; Leff, Bruce

    2011-06-01

    We inform the future development of a new geriatric emergency management practice model. We perform a systematic review of the existing evidence for emergency department (ED)-based case management models designed to improve the health, social, and health service utilization outcomes for noninstitutionalized older patients within the context of an index ED visit. This was a systematic review of English-language articles indexed in MEDLINE and CINAHL (1966 to 2010), describing ED-based case management models for older adults. Bibliographies of the retrieved articles were reviewed to identify additional references. A systematic qualitative case study analytic approach was used to identify the core operational components and outcome measures of the described clinical interventions. The authors of the included studies were also invited to verify our interpretations of their work. The determined patterns of component adherence were then used to postulate the relative importance and effect of the presence or absence of a particular component in influencing the overall effectiveness of their respective interventions. Eighteen of 352 studies (reported in 20 articles) met study criteria. Qualitative analyses identified 28 outcome measures and 8 distinct model characteristic components that included having an evidence-based practice model, nursing clinical involvement or leadership, high-risk screening processes, focused geriatric assessments, the initiation of care and disposition planning in the ED, interprofessional and capacity-building work practices, post-ED discharge follow-up with patients, and evaluation and monitoring processes. Of the 15 positive study results, 6 had all 8 characteristic components and 9 were found to be lacking at least 1 component. Two studies with positive results lacked 2 characteristic components and none lacked more than 2 components. Of the 3 studies with negative results demonstrating no positive effects based on any outcome tested, one

  4. A qualitative readiness-requirements assessment model for enterprise big-data infrastructure investment

    Science.gov (United States)

    Olama, Mohammed M.; McNair, Allen W.; Sukumar, Sreenivas R.; Nutaro, James J.

    2014-05-01

    In the last three decades, there has been an exponential growth in the area of information technology providing the information processing needs of data-driven businesses in government, science, and private industry in the form of capturing, staging, integrating, conveying, analyzing, and transferring data that will help knowledge workers and decision makers make sound business decisions. Data integration across enterprise warehouses is one of the most challenging steps in the big data analytics strategy. Several levels of data integration have been identified across enterprise warehouses: data accessibility, common data platform, and consolidated data model. Each level of integration has its own set of complexities that requires a certain amount of time, budget, and resources to implement. Such levels of integration are designed to address the technical challenges inherent in consolidating the disparate data sources. In this paper, we present a methodology based on industry best practices to measure the readiness of an organization and its data sets against the different levels of data integration. We introduce a new Integration Level Model (ILM) tool, which is used for quantifying an organization and data system's readiness to share data at a certain level of data integration. It is based largely on the established and accepted framework provided in the Data Management Association (DAMADMBOK). It comprises several key data management functions and supporting activities, together with several environmental elements that describe and apply to each function. The proposed model scores the maturity of a system's data governance processes and provides a pragmatic methodology for evaluating integration risks. The higher the computed scores, the better managed the source data system and the greater the likelihood that the data system can be brought in at a higher level of integration.

  5. Using a nursing theory or a model in nursing PhD dissertations: a qualitative study from Turkey.

    Science.gov (United States)

    Mete, Samiye; Gokçe İsbir, Gozde

    2015-04-01

    The aim of this study was to reveal experiences of nursing students and their advisors using theories and models in their PhD dissertations. The study adopted a descriptive qualitative approach. This study was performed with 10 PhD candidates and their five advisors from nursing faculty. The results of the study were categorized into four. These are reasons for using a theory/model in a PhD dissertation, reasons for preferring a given model, causes of difficulties in using models in PhD dissertations, and facilitating factors of using theories and models in PhD of dissertations. It was also reported to contribute to the methodology of research and professional development of the students and advisors. © 2014 NANDA International, Inc.

  6. Methodological Issues and Practices in Qualitative Research.

    Science.gov (United States)

    Bradley, Jana

    1993-01-01

    Discusses methodological issues concerning qualitative research and describes research practices that qualitative researchers use to address these methodological issues. Topics discussed include the researcher as interpreter, the emergent nature of qualitative research, understanding the experience of others, trustworthiness in qualitative…

  7. A Conceptual Model of Dyadic Coordination in HIV Care Engagement Among Couples of Black Men Who Have Sex with Men: A Qualitative Dyadic Analysis.

    Science.gov (United States)

    Tan, Judy Y; Campbell, Chadwick K; Tabrisky, Alyssa P; Siedle-Khan, Robert; Conroy, Amy A

    2018-02-20

    Among Black men who have sex with men (MSM), HIV incidence is disproportionately high and HIV care engagement is disproportionately low. There may be important opportunities to leverage the primary relationship to improve engagement in HIV care and treatment among Black MSM couples. Using dyadic qualitative analysis of semi-structured, one-on-one interviews, we explored dyadic aspects of HIV care engagement among 14 Black MSM couples in which at least one partner was HIV-positive and identified as a Black cisgender man. Findings showed that men varied in how involved they were in their HIV-positive partner's care and treatment, and in how they reciprocated their partner's involvement. Patterns of dyadic HIV care engagement supported a conceptual model of dyadic coordination that describes Black MSM relationships in terms of two conceptual dimensions of dyadic HIV care engagement, and guides future intervention designs with Black MSM couples.

  8. Validation of mathematical models to describe fluid dynamics of a cold riser by gamma ray attenuation; Validacao de modelos matematicos para descrever a fluidodinamica de um riser utilizando atenuacao gama

    Energy Technology Data Exchange (ETDEWEB)

    Melo, Ana Cristina Bezerra Azedo de

    2004-12-15

    The fluid dynamic behavior of a riser in a cold type FCC model was investigated by means of catalyst concentration distribution measured with gamma attenuation and simulated with a mathematical model. In the riser of the cold model, MEF, 0,032 m in diameter, 2,30 m in length the fluidized bed, whose components are air and FCC catalyst, circulates. The MEF is operated by automatic control and instruments for measuring fluid dynamic variables. An axial catalyst concentration distribution was measured using an Am-241 gamma source and a NaI detector coupled to a multichannel provided with a software for data acquisition and evaluation. The MEF was adapted for a fluid dynamic model validation which describes the flow in the riser, for example, by introducing an injector for controlling the solid flow in circulation. Mathematical models were selected from literature, analyzed and tested to simulate the fluid dynamic of the riser. A methodology for validating fluid dynamic models was studied and implemented. The stages of the work were developed according to the validation methodology, such as data planning experiments, study of the equations which describe the fluidodynamic, computational solvers application and comparison with experimental data. Operational sequences were carried out keeping the MEF conditions for measuring catalyst concentration and simultaneously measuring the fluid dynamic variables, velocity of the components and pressure drop in the riser. Following this, simulated and experimental values were compared and statistical data treatment done, aiming at the required precision to validate the fluid dynamic model. The comparison tests between experimental and simulated data were carried out under validation criteria. The fluid dynamic behavior of the riser was analyzed and the results and the agreement with literature were discussed. The adopt model was validated under the MEF operational conditions, for a 3 to 6 m/s gas velocity in the riser and a slip

  9. Adjustment modes in the trajectory of progressive multiple sclerosis: a qualitative study and conceptual model.

    Science.gov (United States)

    Bogosian, Angeliki; Morgan, Myfanwy; Bishop, Felicity L; Day, Fern; Moss-Morris, Rona

    2017-03-01

    We examined cognitive and behavioural challenges and adaptations for people with progressive multiple sclerosis (MS) and developed a preliminary conceptual model of changes in adjustment over time. Using theoretical sampling, 34 semi-structured interviews were conducted with people with MS. Participants were between 41 and 77 years of age. Thirteen were diagnosed with primary progressive MS and 21 with secondary progressive MS. Data were analysed using a grounded theory approach. Participants described initially bracketing the illness off and carrying on their usual activities but this became problematic as the condition progressed and they employed different adjustment modes to cope with increased disabilities. Some scaled back their activities to live a more comfortable life, others identified new activities or adapted old ones, whereas at times, people disengaged from the adjustment process altogether and resigned to their condition. Relationships with partners, emotional reactions, environment and perception of the environment influenced adjustment, while people were often flexible and shifted among modes. Adjusting to a progressive condition is a fluid process. Future interventions can be tailored to address modifiable factors at different stages of the condition and may involve addressing emotional reactions concealing/revealing the condition and perceptions of the environment.

  10. The persistence of subsistence: qualitative social-ecological modeling of indigenous aquatic hunting and gathering in tropical Australia

    Directory of Open Access Journals (Sweden)

    Marcus Barber

    2015-03-01

    Full Text Available Subsistence remains critical to indigenous people in settler-colonial states such as Australia, providing key foundations for indigenous identities and for wider state recognition. However, the drivers of contemporary subsistence are rarely fully articulated and analyzed in terms of likely changing conditions. Our interdisciplinary team combined past research experience gained from multiple sites with published literature to create two generalized qualitative models of the socio-cultural and environmental influences on indigenous aquatic subsistence in northern Australia. One model focused on the longer term (inter-year to generational persistence of subsistence at the community scale, the other model on shorter term (day to season drivers of effort by active individuals. The specification of driver definitions and relationships demonstrates the complexities of even generalized and materialist models of contemporary subsistence practices. The qualitative models were analyzed for emergent properties and for responses to plausible changes in key variables: access, habitat degradation, social security availability, and community dysfunction. Positive human community condition is shown to be critical to the long-term persistence of subsistence, but complex interactions of negative and positive drivers shape subsistence effort expended at the individual scale and within shorter time frames. Such models enable motivations, complexities, and the potential management and policy levers of significance to be identified, defined, causally related, and debated. The models can be used to augment future models of human-natural systems, be tested against case-specific field conditions and/or indigenous perspectives, and aid preliminary assessments of the effects on subsistence of changes in social and environmental conditions, including policy settings.

  11. Qualitative research.

    Science.gov (United States)

    Gelling, Leslie

    2015-03-25

    Qualitative research has an important role in helping nurses and other healthcare professionals understand patient experiences of health and illness. Qualitative researchers have a large number of methodological options and therefore should take care in planning and conducting their research. This article offers a brief overview of some of the key issues qualitative researchers should consider.

  12. Describing and Enhancing Collaboration at the Computer

    Directory of Open Access Journals (Sweden)

    Ken Beatty

    2002-06-01

    Full Text Available Computer-based learning materials differ from classroom practice in that they seldom explicitly offer opportunities for collaboration. Despite this, students do collaborate, helping one another through the content and affordances of computer materials. But, in doing so, students meet with challenges. Paradoxically, these challenges can either inspire or discourage learning and second-language acquisition. This paper, based on research with twenty Hong Kong university students in a controlled experiment, evaluates challenges to collaboration at the computer as evidenced by discourse. The students were videotaped and their discourse transcribed and evaluated both qualitatively and quantitatively, according to a set of discourse markers created to describe collaborative, non-collaborative and ambiguous strategies. The paper begins by exploring the differences between collaboration and similar terms such as teamwork and cooperative learning then goes on to define collaboration in the context of computer-assisted learning. It ends by presenting practical suggestions for software designers, teachers and students to enhance collaboration at the computer.

  13. A mathematical model for describing the retinal nerve fiber bundle trajectories in the human eye: average course, variability, and influence of refraction, optic disc size and optic disc position.

    Science.gov (United States)

    Jansonius, Nomdo M; Schiefer, Julia; Nevalainen, Jukka; Paetzold, Jens; Schiefer, Ulrich

    2012-12-01

    Previously we developed a mathematical model for describing the retinal nerve fiber bundle trajectories in the superior-temporal and inferior-temporal regions of the human retina, based on traced trajectories extracted from fundus photographs. Aims of the current study were to (i) validate the existing model, (ii) expand the model to the entire retina and (iii) determine the influence of refraction, optic disc size and optic disc position on the trajectories. A new set of fundus photographs was collected comprising 28 eyes of 28 subjects. From these 28 photographs, 625 trajectories were extracted. Trajectories in the temporal region of the retina were compared to the existing model. In this region, 347 of 399 trajectories (87%) were within the 95% central range of the existing model. The model was extended to the nasal region. With this extension, the model can now be applied to the entire retina that corresponds to the visual field as tested with standard automated perimetry (up to approximately 30° eccentricity). There was an asymmetry between the superior and inferior hemifields and a considerable location-specific inter-subject variability. In the nasal region, we found two "singularities", located roughly at the one and five o'clock positions for the right optic disc. Here, trajectories from relatively widespread areas of the retina converge. Associations between individual deviations from the model and refraction, optic disc size and optic disc position were studied with multiple linear regression. Refraction (P = 0.021) and possibly optic disc inclination (P = 0.09) influenced the trajectories in the superior-temporal region. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Supporting good practice in the provision of services to people with comorbid mental health and alcohol and other drug problems in Australia: describing key elements of good service models

    Directory of Open Access Journals (Sweden)

    Canaway Rachel

    2010-12-01

    Full Text Available Abstract Background The co-occurrence of mental illness and substance use problems (referred to as "comorbidity" in this paper is common, and is often reported by service providers as the expectation rather than the exception. Despite this, many different treatment service models are being used in the alcohol and other drugs (AOD and mental health (MH sectors to treat this complex client group. While there is abundant literature in the area of comorbidity treatment, no agreed overarching framework to describe the range of service delivery models is apparent internationally or at the national level. The aims of the current research were to identify and describe elements of good practice in current service models of treatment of comorbidity in Australia. The focus of the research was on models of service delivery. The research did not aim to measure the client outcomes achieved by individual treatment services, but sought to identify elements of good practice in services. Methods Australian treatment services were identified to take part in the study through a process of expert consultation. The intent was to look for similarities in the delivery models being implemented across a diverse set of services that were perceived to be providing good quality treatment for people with comorbidity problems. Results A survey was designed based on a concept map of service delivery devised from a literature review. Seventeen Australian treatment services participated in the survey, which explored the context in which services operate, inputs such as organisational philosophy and service structure, policies and procedures that guide the way in which treatment is delivered by the service, practices that reflect the way treatment is provided to clients, and client impacts. Conclusions The treatment of people with comorbidity of mental health and substance use disorders presents complex problems that require strong but flexible service models. While the treatment

  15. Methods for partial differential equations qualitative properties of solutions, phase space analysis, semilinear models

    CERN Document Server

    Ebert, Marcelo R

    2018-01-01

    This book provides an overview of different topics related to the theory of partial differential equations. Selected exercises are included at the end of each chapter to prepare readers for the “research project for beginners” proposed at the end of the book. It is a valuable resource for advanced graduates and undergraduate students who are interested in specializing in this area. The book is organized in five parts: In Part 1 the authors review the basics and the mathematical prerequisites, presenting two of the most fundamental results in the theory of partial differential equations: the Cauchy-Kovalevskaja theorem and Holmgren's uniqueness theorem in its classical and abstract form. It also introduces the method of characteristics in detail and applies this method to the study of Burger's equation. Part 2 focuses on qualitative properties of solutions to basic partial differential equations, explaining the usual properties of solutions to elliptic, parabolic and hyperbolic equations for the archetypes...

  16. Governance arrangements for IT project portfolio management qualitative insights and a quantitative modeling approach

    CERN Document Server

    Frey, Thorsten

    2014-01-01

    Due to the growing importance of IT-based innovations, contemporary firms face an excessive number of proposals for IT projects. As typically only a fraction of these projects can be implemented with the given capacity, IT project portfolio management as a relatively new discipline has received growing attention in research and practice in recent years.?Thorsten Frey demonstrates how companies are struggling to find the right balance between local autonomy and central overview about all projects in the organization. In this context, impacts of different contextual factors on the design of governance arrangements for IT project portfolio management are demonstrated. Moreover, consequences of the use of different organizational designs are analyzed. The author presents insights from a qualitative empirical study as well as a simulative approach.

  17. The qualitative research proposal

    Directory of Open Access Journals (Sweden)

    H Klopper

    2008-09-01

    Full Text Available Qualitative research in the health sciences has had to overcome many prejudices and a number of misunderstandings, but today qualitative research is as acceptable as quantitative research designs and is widely funded and published. Writing the proposal of a qualitative study, however, can be a challenging feat, due to the emergent nature of the qualitative research design and the description of the methodology as a process. Even today, many sub-standard proposals at post-graduate evaluation committees and application proposals to be considered for funding are still seen. This problem has led the researcher to develop a framework to guide the qualitative researcher in writing the proposal of a qualitative study based on the following research questions: (i What is the process of writing a qualitative research proposal? and (ii What does the structure and layout of a qualitative proposal look like? The purpose of this article is to discuss the process of writing the qualitative research proposal, as well as describe the structure and layout of a qualitative research proposal. The process of writing a qualitative research proposal is discussed with regards to the most important questions that need to be answered in your research proposal with consideration of the guidelines of being practical, being persuasive, making broader links, aiming for crystal clarity and planning before you write. While the structure of the qualitative research proposal is discussed with regards to the key sections of the proposal, namely the cover page, abstract, introduction, review of the literature, research problem and research questions, research purpose and objectives, research paradigm, research design, research method, ethical considerations, dissemination plan, budget and appendices.

  18. Perspectives on econometric modelling to inform policy: a UK qualitative case study of minimum unit pricing of alcohol.

    Science.gov (United States)

    Katikireddi, Srinivasa V; Bond, Lyndal; Hilton, Shona

    2014-06-01

    Novel policy interventions may lack evaluation-based evidence. Considerations to introduce minimum unit pricing (MUP) of alcohol in the UK were informed by econometric modelling (the 'Sheffield model'). We aim to investigate policy stakeholders' views of the utility of modelling studies for public health policy. In-depth qualitative interviews with 36 individuals involved in MUP policy debates (purposively sampled to include civil servants, politicians, academics, advocates and industry-related actors) were conducted and thematically analysed. Interviewees felt familiar with modelling studies and often displayed detailed understandings of the Sheffield model. Despite this, many were uneasy about the extent to which the Sheffield model could be relied on for informing policymaking and preferred traditional evaluations. A tension was identified between this preference for post hoc evaluations and a desire for evidence derived from local data, with modelling seen to offer high external validity. MUP critics expressed concern that the Sheffield model did not adequately capture the 'real life' world of the alcohol market, which was conceptualized as a complex and, to some extent, inherently unpredictable system. Communication of modelling results was considered intrinsically difficult but presenting an appropriate picture of the uncertainties inherent in modelling was viewed as desirable. There was general enthusiasm for increased use of econometric modelling to inform future policymaking but an appreciation that such evidence should only form one input into the process. Modelling studies are valued by policymakers as they provide contextually relevant evidence for novel policies, but tensions exist with views of traditional evaluation-based evidence. © The Author 2013. Published by Oxford University Press on behalf of the European Public Health Association.

  19. Numerical and Qualitative Contrasts of Two Statistical Models for Water Quality Change in Tidal Waters

    Science.gov (United States)

    Two statistical approaches, weighted regression on time, discharge, and season and generalized additive models, have recently been used to evaluate water quality trends in estuaries. Both models have been used in similar contexts despite differences in statistical foundations and...

  20. Qualitative validation of humanoid robot models through balance recovery side-stepping experiments

    NARCIS (Netherlands)

    Assman, T.M.; Zutven, van P.W.M.; Nijmeijer, H.

    2013-01-01

    Different models are used in literature to approximate the complex dynamics of a humanoid robot. Many models use strongly varying model assumptions that neglect the influence of feet, discontinuous ground impact, internal dynamics and coupling between the 3D coronal and sagittal plane dynamics.

  1. Women's maternity care needs and related service models in rural areas: A comprehensive systematic review of qualitative evidence.

    Science.gov (United States)

    Hoang, Ha; Le, Quynh; Ogden, Kathryn

    2014-12-01

    Understanding the needs of rural women in maternity care and service models available to them is significant for the development of effective policies and the sustainability of rural communities. Nevertheless, no systematic review of studies addressing these needs has been conducted. To synthesise the best available evidence on the experiences of women's needs in maternity care and existing service models in rural areas. Literature search of ten electronic databases, digital theses, and reference lists of relevant studies applying inclusion/exclusion criteria was conducted. Selected papers were assessed using standardised critical appraisal instruments from JBI-QARI. Data extracted from these studies were synthesised using thematic synthesis. 12 studies met the inclusion criteria. There were three main themes and several sub-themes identified. A comprehensive set of the maternity care expectations of rural women was reported in this review including safety (7), continuity of care (6) and quality of care (6), and informed choices needs (4). In addition, challenges in accessing maternity services also emerged from the literature such as access (6), risk of travelling (9) and associated cost of travel (9). Four models of maternity care examined in the literature were medically led care (5), GP-led care (4), midwifery-led care (7) and home birth (6). The systematic review demonstrates the importance of including well-conducted qualitative studies in informing the development of evidence-based policies to address women's maternity care needs and inform service models. Synthesising the findings from qualitative studies offers important insight for informing effective public health policy. Copyright © 2014 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.

  2. Model endophenotype for bipolar disorder: Qualitative Analysis, etiological factors, and research areas

    Directory of Open Access Journals (Sweden)

    Naraiana de Oliveira Tavares

    2014-12-01

    Full Text Available The aim of this study is to present an updated view of the writings on the endophenotype model for bipolar disorder using analytical methodologies. A review and analysis of networks was performed through descriptors and keywords that characterize the composition of the endophenotype model as a model of health. Information was collected from between 1992 and 2014, and the main thematic areas covered in the articles were identified. We discuss the results and question their cohesion, emphasizing the need to strengthen and identify the points of connection between etiological factors and characteristics that make up the model of endophenotypes for bipolar disorder.

  3. Applying a Qualitative Modeling Shell to Process Diagnosis: The Caster System. ONR Technical Report #16.

    Science.gov (United States)

    Thompson, Timothy F.; Clancey, William J.

    This report describes the application of a shell expert system from the medical diagnostic system, Neomycin, to Caster, a diagnostic system for malfunctions in industrial sandcasting. This system was developed to test the hypothesis that starting with a well-developed classification procedure and a relational language for stating the…

  4. Toward a Qualitative Analysis of Standardized Tests Using an Information Processing Model.

    Science.gov (United States)

    Armour-Thomas, Eleanor

    The use of standardized tests and test data to detect and address differences in cognitive styles is advocated here. To this end, the paper describes the componential theory of intelligence addressed by Sternberg et. al. This theory defines the components of intelligence by function and level of generality, including: (1) metacomponents: higher…

  5. A chaotic-dynamical conceptual model to describe fluid flow and contaminant transport in a fractured vadose zone. 1997 progress report and presentations at the annual meeting, Ernest Orlando Lawrence Berkeley National Laboratory, December 3-4, 1997

    International Nuclear Information System (INIS)

    Faybishenko, B.; Doughty, C.; Geller, J.

    1998-07-01

    Understanding subsurface flow and transport processes is critical for effective assessment, decision-making, and remediation activities for contaminated sites. However, for fluid flow and contaminant transport through fractured vadose zones, traditional hydrogeological approaches are often found to be inadequate. In this project, the authors examine flow and transport through a fractured vadose zone as a deterministic chaotic dynamical process, and develop a model of it in these terms. Initially, the authors examine separately the geometric model of fractured rock and the flow dynamics model needed to describe chaotic behavior. Ultimately they will put the geometry and flow dynamics together to develop a chaotic-dynamical model of flow and transport in a fractured vadose zone. They investigate water flow and contaminant transport on several scales, ranging from small-scale laboratory experiments in fracture replicas and fractured cores, to field experiments conducted in a single exposed fracture at a basalt outcrop, and finally to a ponded infiltration test using a pond of 7 by 8 m. In the field experiments, they measure the time-variation of water flux, moisture content, and hydraulic head at various locations, as well as the total inflow rate to the subsurface. Such variations reflect the changes in the geometry and physics of water flow that display chaotic behavior, which they try to reconstruct using the data obtained. In the analysis of experimental data, a chaotic model can be used to predict the long-term bounds on fluid flow and transport behavior, known as the attractor of the system, and to examine the limits of short-term predictability within these bounds. This approach is especially well suited to the need for short-term predictions to support remediation decisions and long-term bounding studies. View-graphs from ten presentations made at the annual meeting held December 3--4, 1997 are included in an appendix to this report

  6. Materials model for describing the austenite-martensite phase transformation considering transformation-induced plasticity; Ein Materialmodell zur Beschreibung der Austenit-Martensit Phasentransformation unter Beruecksichtigung der transformationsinduzierten Plastizitaet

    Energy Technology Data Exchange (ETDEWEB)

    Oberste-Brandenburg, C.

    1999-06-01

    In this thesis, a model to describe the austenite martensite transformation was developed. The transformation induced plasticity (TRIP) was taken into consideration. The model can be used to design complex structures. A local examination of the energy and entropy balance at the phase boundary serves as the starting point for the identification of the thermodynamical driving force and the thermodynamic flow. For both, a tensorial description is necessary for a general nonhydrostatically stressed solid. In the second part, a material law for the description of TRIP-Steels was developed based on the values derived in the first part. The different mechanical behavior of the phases, especially the differing yield stresses, was taken into account. The model developed was implemented into the finite element program MARC. Simulations of the material and the structural behavior were performed. The experimentally observed strong dependence of the transformation kinetics on the yield stress of the austenite and the dependence of the orientation of the martensite inclusion on the stress state could be verified. (orig.) [German] Im Rahmen dieser Arbeit wurde ein Materialmodell zur Beschreibung der Austenit-Martensit Phasenumwandlung unter Beruecksichtigung der transformationsinduzierten Plastizitaet (TRIP) entwickelt. Das Modell ist zur Berechnung ausgedehnter Strukturen einsetzbar. Eine lokale Betrachtung der Energie- und Entropiebilanz an der Phasengrenze bildet den Ausgangspunkt zur Identifikation der thermodynamischen Kraft und des thermodynamischen Flusses bei Beschreibung der Transformationskinetik. Fuer beide Groessen muss fuer den allgemein nichthydrostatischen Spannungszustand eine tensorielle Beschreibung verwendet werden. Im zweiten Teil der Arbeit bilden diese Groessen die Basis zur Entwicklung eines Stoffgesetzes zur Beschreibung des TRIP-Phaenomens. Es wird das unterschiedliche mechanische Verhalten der Phasen, insbesondere die stark unterschiedlichen

  7. Modeling grain boundaries in polycrystals using cohesive elements: Qualitative and quantitative analysis

    Energy Technology Data Exchange (ETDEWEB)

    El Shawish, Samir, E-mail: Samir.ElShawish@ijs.si [Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Cizelj, Leon [Jožef Stefan Institute, Jamova cesta 39, SI-1000 Ljubljana (Slovenia); Simonovski, Igor [European Commission, DG-JRC, Institute for Energy and Transport, P.O. Box 2, NL-1755 ZG Petten (Netherlands)

    2013-08-15

    Highlights: ► We estimate the performance of cohesive elements for modeling grain boundaries. ► We compare the computed stresses in ABAQUS finite element solver. ► Tests are performed in analytical and realistic models of polycrystals. ► Most severe issue is found within the plastic grain response. ► Other identified issues are related to topological constraints in modeling space. -- Abstract: We propose and demonstrate several tests to estimate the performance of the cohesive elements in ABAQUS for modeling grain boundaries in complex spatial structures such as polycrystalline aggregates. The performance of the cohesive elements is checked by comparing the computed stresses with the theoretically predicted values for a homogeneous material under uniaxial tensile loading. Statistical analyses are performed under different loading conditions for two elasto-plastic models of the grains: isotropic elasticity with isotropic hardening plasticity and anisotropic elasticity with crystal plasticity. Tests are conducted on an analytical finite element model generated from Voronoi tessellation as well as on a realistic finite element model of a stainless steel wire. The results of the analyses highlight several issues related to the computation of normal and shear stresses. The most severe issue is found within the plastic grain response where the computed normal stresses on a particularly oriented cohesive elements are significantly underestimated. Other issues are found to be related to topological constraints in the modeling space and result in the increased scatter of the computed stresses.

  8. Qualitative evaluation of various models for mechanical analysis of nuclear wastes storage in brittle rocks

    International Nuclear Information System (INIS)

    Millard, A.

    1994-01-01

    In order to appraise the large scale behaviour of high level nuclear wastes underground repositories in brittle rocks, basic models are presented and evaluated in the case of generic repository configurations. Predictive Capabilities of the models are briefly discussed. 7 figs

  9. Ajuste de modelos estocásticos lineares e não-lineares para a descrição do perfil longitudinal de árvores Fitting linear and nonlinear stochastic models to describe longitudinal tree profile

    Directory of Open Access Journals (Sweden)

    Leonardo Machado Pires

    2007-10-01

    Full Text Available Os modelos polinomiais são mais difundidos no meio florestal brasileiro na descrição do perfil de árvores devido à sua facilidade de ajuste e precisão. O mesmo não ocorre com os modelos não-lineares, os quais possuem maior dificuldade de ajuste. Dentre os modelos não-lineares clássicos, na descrição do perfil, podem-se citar o de Gompertz, o Logístico e o de Weibull. Portanto, este estudo visou comparar os modelos lineares e não lineares para a descrição do perfil de árvores. As medidas de comparação foram o coeficiente de determinação (R², o erro-padrão residual (s yx, o coeficiente de determinação corrigido (R²ajustado, o gráfico dos resíduos e a facilidade de ajuste. Os resultados ressaltaram que, dentre os modelos não-lineares, o que obteve melhor desempenho, de forma geral, foi o modelo Logístico, apesar de o modelo de Gompertz ser melhor em termos de erro-padrão residual. Nos modelos lineares, o polinômio proposto por Pires & Calegario foi superior aos demais. Ao comparar os modelos não-lineares com os lineares, o modelo Logístico foi melhor em razão, principalmente, do fato de o comportamento dos dados ser não-linear, à baixa correlação entre os parâmetros e à fácil interpretação deles, facilitando a convergência e o ajuste.Polynomial models are most commonly used in Brazilian forestry for taper modeling due to its straightforwardly fitting and precision. The use of nonlinear regression classic models, like Gompertz, Logistic and Weibull, is not very common in Brazil. Therefore, this study aimed to verify the best nonlinear and linear models, and among these the best model to describe the longitudinal tree profile. The comparison measures were: R², syx, R²adjusted, residual graphics and fitting convergence. The results pointed out that among the non-linear models the best behavior, in general, was given by the Logistic model, although the Gompertz model was superior compared with the Weibull

  10. Simplified Qualitative Discrete Numerical Model to Determine Cracking Pattern in Brittle Materials by Means of Finite Element Method

    Directory of Open Access Journals (Sweden)

    J. Ochoa-Avendaño

    2017-01-01

    Full Text Available This paper presents the formulation, implementation, and validation of a simplified qualitative model to determine the crack path of solids considering static loads, infinitesimal strain, and plane stress condition. This model is based on finite element method with a special meshing technique, where nonlinear link elements are included between the faces of the linear triangular elements. The stiffness loss of some link elements represents the crack opening. Three experimental tests of bending beams are simulated, where the cracking pattern calculated with the proposed numerical model is similar to experimental result. The advantages of the proposed model compared to discrete crack approaches with interface elements can be the implementation simplicity, the numerical stability, and the very low computational cost. The simulation with greater values of the initial stiffness of the link elements does not affect the discontinuity path and the stability of the numerical solution. The exploded mesh procedure presented in this model avoids a complex nonlinear analysis and regenerative or adaptive meshes.

  11. Detailed qualitative dynamic knowledge representation using a BioNetGen model of TLR-4 signaling and preconditioning.

    Science.gov (United States)

    An, Gary C; Faeder, James R

    2009-01-01

    Intracellular signaling/synthetic pathways are being increasingly extensively characterized. However, while these pathways can be displayed in static diagrams, in reality they exist with a degree of dynamic complexity that is responsible for heterogeneous cellular behavior. Multiple parallel pathways exist and interact concurrently, limiting the ability to integrate the various identified mechanisms into a cohesive whole. Computational methods have been suggested as a means of concatenating this knowledge to aid in the understanding of overall system dynamics. Since the eventual goal of biomedical research is the identification and development of therapeutic modalities, computational representation must have sufficient detail to facilitate this 'engineering' process. Adding to the challenge, this type of representation must occur in a perpetual state of incomplete knowledge. We present a modeling approach to address this challenge that is both detailed and qualitative. This approach is termed 'dynamic knowledge representation,' and is intended to be an integrated component of the iterative cycle of scientific discovery. BioNetGen (BNG), a software platform for modeling intracellular signaling pathways, was used to model the toll-like receptor 4 (TLR-4) signal transduction cascade. The informational basis of the model was a series of reference papers on modulation of (TLR-4) signaling, and some specific primary research papers to aid in the characterization of specific mechanistic steps in the pathway. This model was detailed with respect to the components of the pathway represented, but qualitative with respect to the specific reaction coefficients utilized to execute the reactions. Responsiveness to simulated lipopolysaccharide (LPS) administration was measured by tumor necrosis factor (TNF) production. Simulation runs included evaluation of initial dose-dependent response to LPS administration at 10, 100, 1000 and 10,000, and a subsequent examination of

  12. A functional language for describing reversible logic

    DEFF Research Database (Denmark)

    Thomsen, Michael Kirkedal

    2012-01-01

    Reversible logic is a computational model where all gates are logically reversible and combined in circuits such that no values are lost or duplicated. This paper presents a novel functional language that is designed to describe only reversible logic circuits. The language includes high....... Reversibility of descriptions is guaranteed with a type system based on linear types. The language is applied to three examples of reversible computations (ALU, linear cosine transformation, and binary adder). The paper also outlines a design flow that ensures garbage- free translation to reversible logic...... circuits. The flow relies on a reversible combinator language as an intermediate language....

  13. Hierarchy of models: From qualitative to quantitative analysis of circadian rhythms in cyanobacteria

    Science.gov (United States)

    Chaves, M.; Preto, M.

    2013-06-01

    A hierarchy of models, ranging from high to lower levels of abstraction, is proposed to construct "minimal" but predictive and explanatory models of biological systems. Three hierarchical levels will be considered: Boolean networks, piecewise affine differential (PWA) equations, and a class of continuous, ordinary, differential equations' models derived from the PWA model. This hierarchy provides different levels of approximation of the biological system and, crucially, allows the use of theoretical tools to more exactly analyze and understand the mechanisms of the system. The Kai ABC oscillator, which is at the core of the cyanobacterial circadian rhythm, is analyzed as a case study, showing how several fundamental properties—order of oscillations, synchronization when mixing oscillating samples, structural robustness, and entrainment by external cues—can be obtained from basic mechanisms.

  14. Supporting conceptual modelling of dynamic systems: A knowledge engineering perspective on qualitative reasoning

    NARCIS (Netherlands)

    Liem, J.

    2013-01-01

    Research has shown that even students educated in science at prestigious universities have misconceptions about the systems underlying climate change, sustainability and government spending. Interactive conceptual modelling and simulation tools, which are based on Artificial Intelligence techniques,

  15. Method of modelization assistance with bond graphs and application to qualitative diagnosis of physical systems

    International Nuclear Information System (INIS)

    Lucas, B.

    1994-05-01

    After having recalled the usual diagnosis techniques (failure index, decision tree) and those based on an artificial intelligence approach, the author reports a research aimed at exploring the knowledge and model generation technique. He focuses on the design of an aid to model generation tool and aid-to-diagnosis tool. The bond graph technique is shown to be adapted to the aid to model generation, and is then adapted to the aid to diagnosis. The developed tool is applied to three projects: DIADEME (a diagnosis system based on physical model), the improvement of the SEXTANT diagnosis system (an expert system for transient analysis), and the investigation on an Ariane 5 launcher component. Notably, the author uses the Reiter and Greiner algorithm

  16. A qualitative comparison of fire spread models incorporating wind and slope effects

    Science.gov (United States)

    David R. Weise; Gregory S. Biging

    1997-01-01

    Wind velocity and slope are two critical variables that affect wildland fire rate of spread. The effects of these variables on rate of spread are often combined in rate-of-spread models using vector addition. The various methods used to combine wind and slope effects have seldom been validated or compared due to differences in the models or to lack of data. In this...